Cool Engineering

More student projects

2011-09-27T14:39:00.003+10:00

The engineering students at La Trobe are always turning out interesting projects that I get to supervise. Here a a couple of videos of recent robots:

3D printing - Veroboard Base

2010-11-24T10:08:00.003+11:00

I've been using the UP! 3D printer for 2 weeks now and one of the common problems I've had along with other is warping of the corners for large prints. People have been using the paint, blue painters tape, kapton tape and other such ideas. I've tried the paint and blue 3M tape with mixed results and been a bit annoyed with the high maintainence.
It was then we stumbled across a really simple solution - veroboard. Veroboard is basically a PCB with lots of regularly placed holes. When you print the bottom layer goes into some of these holes and sets - keeping the model firmly anchored to the base.

Printing in 3D

2010-11-17T21:46:00.006+11:00

Well one of the most exciting gadgets i've been using recently isn't the remote control watch (although that is pretty cool) but a 3D printer. The printer basically works by melting and extruding ABS plastic in a 3D pattern you have designed in some CAD software like Solidworks.
So far I've printed an assortment of servo brackets, a mounting assembly for my PhD research and a some hardware for Adam's CNC machine design.
For those curious the printer is this one: http://pp3dp.com/

Student projects

2010-05-22T11:43:00.002+10:00

Every year I've been teaching at uni I have been supervising some pretty interesting and cool final year student projects. In the past these have included submarines, walking robots, flying robots, intelligent taps and even some robosoccer action. This year promises the same with a number of UAV guidance and targetting systems, Rubik's cube solving robots, in-car CAN bus monitors and even a (minature) Segway!
For now though I have some videos from some of last years rad projects:

Peter's Quad rotor helicopter:

Duc's Insectabot:

Daniel, Evan and Ruskin's Soccerbot:

Soldering Tutorials

2010-05-18T19:24:00.002+10:00

This is my third year of lecturing a microcontrollers subject at university. One of the labs not closely related to microcontrollers, but a useful skill for electronic engineers to have is soldering. This year I decided to go away from individual soldering demonstrations for each student at their desks and go for the YouTube approach.
The through-hole video shows a very standard through hole approach, whereas the SMT video shows a "Tack-and-hold" approach which uses only a matchstick as the specialised tool.
Enjoy

Followup ROV tests

2008-10-19T13:18:00.002+11:00

Several modification have been made to the ROV to improve performance:
- The large buoyancy tanks have been removed and replaced with smaller strips of foam
- Some holes were cut in the bottom grate to improve water flow.
- Sinkers have been fitted to fine-tune the buoyancy
- 12V 3A SLA battery was fitted
The results were the ROV is now considerably faster - 14cm/second with a turn speed of 45 degrees per second.

ROV Motor Shrouds

2008-10-01T22:06:00.002+10:00

When using the ROV in the moat it was noticed that weed getting caught in the propellors was a significant issue. Also if the ROV gets too close to the wall the propellors can hit the wall stalling the motors - probably not too good for the motor controllers! (Current limiting was one feature I didn't explicitly build in for lack of microcontroller pins).
Below are some photos of the motor shrouds - they are not yet on the ROV as they need some minor alterations.
They were basically lengths of 100mm PVC pipe with slots cut out and then bent into position (when heated with a blowtorch). Besides that you can see what I had for dinner the previous night.

Bus Addressable Motor Driver

2008-09-30T14:44:00.003+10:00

Information on the motor shrouds is coming but will be delayed another couple of days as I didn't follow the measure first rule and made them too small to fit over the propellers. The new 100mm shrouds have now been made and will be fitted in the next few days.
On the topic of motors - another interesting little board inside the ROV is the motor control board. I decided to make this generic as possible so it can be reused in different vehicles (including my PhD project!) in different conditions with minimum overhead.
Here are the specs:
- Bi-Directional motor driver up to 4A (implemented using a H-Bridge made up of FETs) (with heavier wiring we could go higher)
- Microprocessor driven
- H-Bridge shoot-through logical prevention
- Bus operated - connect up to 4 on the same bus line and refer to each by a different address
- With the flick of a switch it accepts a direct PWM and direction signal rather than the serial addressed scheme
A website for this has been thrown up too.

ROV braves the Moat

2008-09-29T15:04:00.002+10:00

The ROV has officially been in real water (not including the bathtub). The first testing ground was the Professor's swimming pool and the follow-up test was in the University moat system.
The initial tests show both positive and negative results:
The good:
- No leaks were encountered at all - the ROV was taken down to a maximum depth of 1.7m and was underwater for approximately an hour in total - not a single drop of water was found inside.
- There is ton's of bouyancy to play with - we literally had to add approximately 3kg of extra weight to make it neutrally bouyant
- The ROV moved around under computer control as expected
- A great crowd attractor with many people particularly at University coming up to take a look and ask questions (and offer advice!)

The not-so-good:
- The ROV was quite slow (see video). In the first test this was due in part to the batteries not being installed correctly. It still seems to be an issue and so we probably will need to swap the NiMH batteries with the SLA that we had originally planned on using with a lower internal resistance
- It was really heavy - with all the extra weight - I'm considering replacing our big ballast tanks with some stabalising foam and we should be able to reduce our weight significantly - hopefully allowing it to be a bit faster
- The propellors had a habit of catching weeds and junk (leading me to finally build the propellor guards - to be discussed in the next post)
To do:
- Fit propellor guards
- Re-adjust bouyancy to ensure overall load can be lightened
- Trim off to neutral bouyancy using lead sinkers ($3.30 from Kmart)
- Fit SLA 12V 3A Battery
- Retest
The sports centre at the Uni has given permission to perform testing in the deep water section of the pool (2.8 m from memory) but that won't be to mid next week - they are draining the pool for the break - so until then we will be testing probably in the moat or other swimming pools.

POV and Project of the Month

2008-09-28T00:02:00.002+10:00

The previous post mentioned the POV project whilst lacking some detail or any conclusion for the matter. The POV project was completed and looked really great on open day. Unfortunately we ran out of time to get the wireless updates running but is successfully wrote LA TROBE pretty clearly through the lab causing lots of people to point and stare. A page on my website has now been created for the POV.
This project was the first of a new initiative which has been named 'Project of the Month' - for lack of a better name. Basically it is a staff/student mentorship program which aims to address three key areas:
- Many staff have ideas small projects they would like to create but don't have the time
- Many students want extra project experience but need some direction and motivation and will benefit hugely skills wise
- The more presentations at Open Day the better - and many of these types of projects would be more than suitable
I supervised the first 'Project of the Month' and a rather bright third year student (Duc) completed the project. It is preferrable to keep the projects short so that it doesn't interfer too much with other academic activities for both staff and students. Right now I have half a whiteboard full of project ideas - so it looks like it will be a fun summer.
If anyone has any other ideas for a short project please send them through.

Open Day Reflections

2008-09-27T16:41:00.003+10:00

How quickly the time has gone already nearly a month since La Trobe Uni Open Day.
We had about 7 engineering displays in total:
- The UAV
- The ROV
- A line tracking robot
- A Persistence of vision sign writer
- A traffic congestion Zigbee and GPS based monitoring system
- Some fancy image recognition for speed signs
- A waveform generator
When people walked in they were often really interested in moving things and interactive things - the POV and line tracking robot in particular attracted lots of attention. Unfortunately the ROV and UAV as cool as they are were simply static displays which weren't too exciting. Next year we will aim to have more interactive and visually stimulating projects, in particular some we have earmarked include:
- A hexapod insectoid robot
- A horizontal 3D POV display
- A PID balance beam or inverted pendulum
- My PhD research on SLAM (Simultaneous Localisation and Mapping)
- An active ROV display (people control the ROV)
- Mini-ROV's in a fish-tank (from the schools program)
- High altitude balloon research
- Quadrature rotor chopper

Line following robot Rev2

2008-06-11T10:32:00.003+10:00

The battery powered line following robot is all built up and running around the floor!

Walk the line - Version 2

2008-06-06T20:33:00.003+10:00

The picture below shows the PCB for Rev2 for the line following robot. It has a few upgrades and modifications on Rev1, namely:
- Operates off 6V supply (4AA batteries) - Rev1 was designed to operate off 4.5V (3 batteries) but this wasn't enough voltage for the motors - hence the upgrade
- The footprint on the pots fixed - just messed up the numbering of the pins - grr
- Removed some testing LED's - the algorithm has been verified now so I can free up some boardspace

Interestingly I'm still looking for a better way of protecting PCB's - the following have been tried:
- No protection: copper corrodes and looks horrible
- Leaving photo resist layer on - it eventually scratches off in patches, that corrodes and looks horrible
- Solder screening - invariably some bridges are created which need to be tracked down, doesn't look particularly nice
- Spray on coating (currently use) - dries overnight, smells horrible, makes a bit of a mess when soldering - but does the job fairly well (although it can be a bit patchy) - possibly I have to try some different spray on coatings

POV Plans

2008-06-05T20:29:00.004+10:00

After quickly coding up some C code to drive LEDs I was quickly able to write some POV based messages when the LED line was waved through the air. Unfortunately I didn't have a chance to take any photos of the writing that was being flashed through the air. The grand plan for open day is to use a wireless MSP430 module to allow us to wirelessly program whatever message we would like.

Below I have included a couple of photos that were taken from the version 1 line tracking robot. For interests sake the CD that I used for the baseplate was from the TI microprocessors that didn't quite work - the device ID for the USB driver was wrong (and the version of IAR studio was 2 versions old).

Walk the line

2008-06-04T22:52:00.003+10:00

Yesterday I finally assembled the line-following robot (the latest of my robotic creations) into a form that I could code up and test. An hour or two later the PID algorithms were more or less working (currently only the 'P' is tuned in) and my line following robot is following lines.
In the video you will see some power cables and such detracting features as the photo-sensors being held on with electrical tape. Thesether than simply running around on my desk following the oval like (or an alternate circuit looks sowill be remedied in version 2 - which will be powered by 4 AA batteries and will have a proper sensor mounting system. This will give it greater range of mobility so we can plot a path to follow around the lab rather than on my desk around the oval like (or alternately an track looking something like Australia if you squint) printed track.

Clocking a POV demonstration

2008-05-13T23:08:00.003+10:00

With open day coming up again at Uni (a couple of months away still) I've been brainstorming different ideas which would have a good visual aspect to them. One such is a fairly simple line following robot - the board for which has been made and I'm slowly assembling. It will be based around an AT Tiny2313. Realistically is could have been implemented using an AT Tiny13 - but I wouldn't have gotten huge amount of feedback as to what state the PID was in so it would have been more difficult to design the control algorithms. Now we have extra LEDs and pins to spare.
The other project I've been pondering is a POV (Persistence of Vision) toy. Now according to Wikipedia is seems the term Persistence Of Vision is rather inaccurate as it was based on a flawed concept of how humans interpret motion. It seems that thinking about persistence of vision treats the eye as more of a crude camera - wherein it is more complex all together. Either way basically we want to quickly move a changing line of LED's, thereby allowing us to write messages or display patterns. Some people have put together this device as a handheld writing device which would be pretty cool for open day - one concern is that someone will eventually get wacked in the head - or we have some sort of issue like with the flying Wii remotes. Another common implementation is to have a rotating line of LEDs and to change the text based on the position of the rotation arm. Additionally it'd be kind of cool to have it wirelessly updatable, and we would need some sort of sensory feedback as to what point the arm is at so we can get all our timing right. For doing that I'm currently thinking a photodiode and either an IR LED or a black/white printed piece of paper will work similar to the line following robot - another common technique seems to be using a hall effects sensor and a magnet. In code this will be interrupt driven and continually dump out the value in a free running hardware timer before resetting the value of the timer.
For planning purposes it is important to get something that actually swings - and does so at a descent enough speed. Trialling a few different small DC motors I clamped the motor and a vice attached a small metal bar (with some batteries connected to simulate the final product). To calculate the speed of rotation I affixed a bright torch (Surefire - yes it was overkill!) and on the other side positioned a photodiode which was connected up to my CRO. Now it was a simple matter of reading the waveform off the CRO and to my delight we were doing 33 revolutions per second - which considering PAL is 25 frames per second - should be enough. I was only driving the motor at 3V and it was rated to 6V (so we have some room to move!)

Study trip to Brisbane

2008-05-11T21:42:00.002+10:00

Last week marked I conducted a whirlwind 2 day study trip to Brisbane involving visiting CSIRO, QUT and UofQ. Several points that stood out from all of this:
- CSIRO is really cool and produce amazing autonomous stuff from submarines to bobcats!
- QUT has a really cool UAV department and some very switched on PhD students
- UofQ has some great mechatronics facilities
- All of the people I talked to were without exception really friendly, made time in their busy schedules and offered really helpful PhD advice
- It seems impossible to get free WIFI in Brisbane.

Course material availablity

2008-04-15T22:34:00.002+10:00

To get around some shortcomings in the current method of course material disemination I have provided course material for the subject (microprocessors and digital design) on my website at: http://www.ee.latrobe.edu.au/~rjr/ELE2MDD/ELE2MDD.html
It will probably come down over second semester so look at it while it is still there.

Dilution of work

2008-04-15T22:21:00.002+10:00

At times one becomes frustrated on the lack of progress with particular project - why havn't I been able to finish this yet it isn't too hard? The answer I'm thinking at the moment which is more than applicable to me is one of dilution to take a chemistry adage (probably part in due to all the PCB's I've recently been etching). When a chemical (take Ammonium Persulphate for example - my current etchant of choice) is diluted it will still etch boards - just a whole lot slower. This seems apparent to how projects are coming along - between lecturering, supervising, researching, consulting and leading 2 study groups the time spent on projects seems somewhat diluted.
Realistically if I had one week completely free of distractions I could probably finish all the code for the submarine and have it running the the water for some testing - but when is that week going to come - not soon it would seem.

Team ROV!

2008-02-16T21:10:00.002+11:00

The last two months have seen me very busy writing lectures, assignments, laboratories and tutorials for a new second year subject in Microprocessors and Digital Design (ELE2MDD). As a result work on the ROV has been slow of late.
One really positive development is that three students have now signed on to complete the project as their final year engineering project. Our first meeting on Wednesday was an excellent brainstorming session with the guys coming up with some super ideas. I'm looking forward to some excellent results and the guys creating a super ROV project that will be the project of the year!

Naughty little firewalls

2008-02-16T21:01:00.002+11:00

As someone with a computer/engineering background I often get requests to fix computers and questions on how to fix them (I actually got one from a dental nurse yesterday just before the dentist went to work).
The last two house calls that I have done in the last week had similar symptoms and the same root cause. Internet access was either not-existent or program dependent. I have come to suspect 3rd party anti-virus and firewall software when these sorts of problems occur - if only I relied on my first instincts every time.
The first job I quickly uninstalled the anti-virus and firewall package. I then installed AVG Free Anti-virus and enabled the Windows firewall. Problem fixed completely and all over in under half an hour.
The second job had about 5 different things going wrong including wireless printers and messages popping up left, right and centre. Though the anti-virus and firewall software was different, it was still the root cause - sneakily blocking all internet access and locking out the computer from accessing the wireless printer. So once again the solution was the same, but I'd only came to this realisation after about 3.5 hours and two visits.

Macgyver charging my phone

2008-01-23T20:27:00.000+11:00

Today I found myself in a lab expecting a phone call - only one problem. My phone was currently showing 3% charge - not good!
After asking around if anyone had an Ericsson charger, I was left to try and get some charge into my phone another way. After googling for pinouts I found just what I needed.
Using a breadboard, a lab powersupply and some wire the phone was up to 60% charge in half an hour or so.
Note: If you don't know what you are doing - don't try it (and turn off your vibrate, unless you want sparks to fly when the phone rings)

PhD Announcement

2007-12-23T12:44:00.000+11:00

After much prodding and and suggesting from fellow engineers and scientists I have decided to commence a PhD in 2008. The topic will be initially broadly related to underwater robotic vehicles and will hopefully develop into autonomous fault tolerant control of my ROV. Apart from this I will be writing the lecture notes for a second year subject encompassing digital electronics and microprocessors, delivering some of the lectures, writing labs and tutes - and in general being somewhat of an academic.
Having said that I should now have more time for engineering consulting - so contact me with project propositions.

More PCB's

2007-12-21T08:10:00.000+11:00

One of my current projects (the UV PCB exposer) is currently on hold as one of the guys from work gave me his one that he made a month or so back. Last night it had its first work out and exposed two boards with excellent results.

PCB Work

2007-12-13T21:49:00.000+11:00

Over the last week or so I decided to get cracking and try and complete some projects that I have been working on for ages. To facilitate this I turned out 2 PCB's in a week - one to control the ROV complete with H-Bridge drivers for each of the motors and the other to control the agitator project. Having tried a couple of different etching techniques I always find I'm happy with the photo - etching results, and yet again the photo etching gave excellent results on what is a reasonably complex board.

Controlling the ROV

2007-12-01T15:55:00.000+11:00

Yesterday I picked up Visual basic again after a 3 year absence and threw together a controller for the ROV. This is initially just for prototyping and will enable the user to control each of the 3 thrusters, as well as arming and disarming the ROV.
I have initially chosen a standard similar to the NEMA standard used by GPS recievers. This is a simple layout with comma delimiters, an XOR based checksum and clearly defined message bounds ($ and *).

Stove Project Page

2007-11-18T09:02:00.000+11:00

I have recently been adding more techincal pages at http://www.rross.com.au/tech/
The lastest complete page is the stove writeup - which includes two videos, one on making the stove and the other on using the stove. Enjoy!
http://www.rross.com.au/tech/stove/stove.html

Throat Mic Photos

2007-10-07T22:33:00.001+10:00

As requested here are some photos of the throat mic mod:

The completed throat mic (identical to the original from the outside)Throat mic with the microphone pickup circuitry displayed:

Electret mic condenser from Dick Smith or Jaycar electronics (~$3)

Throat Mic Mods

2007-10-07T17:59:00.000+10:00

Having experimented several years ago with different tactical setups for my 'army games' I had touched upon using throat mics (not that dissimilar to what special forces use). One problem I encountered was mounting the mic so it would stay pretty much in position as I moved, and making the earpiece robust enough so that it could survive our tactical incursions.
Skipping forward 7 years I decided to purchase a cheap throat-mic off eBay (figuring this might help out for outdoor paintball). I have Uniden CB radio's, but since I couldn't find any throat mic's for them I went with an iCom mic - which had the same connector on it - I figured it would do basically the same thing. Skipping forwards a week - the mic arrived, I plugged it in and got absolutely nothing. Sound would come out of the earpiece and when I tapped it vibrations would come though the other end, but no voice. Whipping out the meter, I found that the resistance across the mic connector on the throat mic was double that of my (aftermarket Uniden) handset. Opening up the Uniden handset revealed a very simple circuit: an electret mic condenser in parallel with a 100pF cap and a 3.3K resistor. Upon discovering this I removed the flatter mic element from the throat mic with its connected circuitry and duplicated the circuit I found in the Uniden handset. Though repeated testing I found that in a throat mic configuration that it seemed to work better without the cap and resistor - I guess because it is working on more delicate vibrations from the voice box as opposed to a direct pressure wave. The cap would likely act as a high-pass filter, while the resistor in parallel with the mic resistance would reduce the sensitivity whilst possibly shifting down the non-actuated resistance to a lower level.

Paintballing - Melbourne indoor paintball

2007-10-04T22:08:00.000+10:00

Although this is not strictly and engineering post, I have observed that a huge number of techies enjoy paintballing - possibly tied in with all the FPS they played as kids (and older kids). Last weekend was my 4th paintballing incursion, at my 3rd venue. It was also my first time indoor paintballing, which added quite a new dimension to the game.

The floor was carpeted and absolutely covered in paintballs and a smearing of paint. This made for some great diving action - allowing me to do huge power-slides to get behind cover. My commando like tactics came at a cost though – over all the games I was hit only a handful of times - and only have one bruise to show, but my whole body came away aching. Lessons from this: 1) stretch first, 2) I'm not Jason Bourne.

Some other interesting dynamics of indoor paintball were:

- All the barriers were blowup air filled barriers - and would move if you touched them - so you could work out were people were by seeing what moved.

- Since everyone was much closer in I couldn't use my ears as much to determine when the enemy was firing and withdraw before the paint started reaching me - I can normally do this outdoors.

- There wasn't a noticeable change in pitch when the gun was just firing air as opposed to paint. Possibly because outdoor It was lost quieter I could notice a change in pitch when you turned the gun upside-down and fired just air - indoor they sounded much more similar.

Learning to Fly

2007-09-22T16:07:00.000+10:00

I spent the morning teaching a good mate and his dad to fly (model aircraft that is). Being fresh in my mind I thought I'd share some tips to try and make RC flying easier - particularly for the beginner.
1) Have an experienced instructor along with you
2) Fly in an area with plenty of open space - most of my crashes have been because I have been confined to an area which was too small
3) Fly high - don't start out low level flying it is too hazardous and doesn't allow you time to react - try to fly between 50-150m
4) Have a second person as a spotter in case you loose sight of the plane momentarily (this is an emergency thing)
5) Take off into wind, land into wind
6) Don't fly in front of the sun - it will blind you and you will loose sight of the plane
7) Don't fly until you have tested all the controls on the ground - ensure they are not reversed! and that you are comfortable with the configuration. (I have throttle on left stick, rudder and elevator on right stick) - If I had ailerons, these would displace the rudder on the right stick
8) Do a range test on the ground - do the controls work from 20m with the aerial fully down (not extended)?
9) Wear a hat and sunglasses
10) Don't take on the wind - if it is too windy (more than a light breeze for inexperienced pilots) save your plane for a less windy day
11) Stay away from trees - they are not friendly to planes (as a side issue a weight with fishing line then tied to a heavy rope generally works for getting them down).

More robots on the way

2007-09-21T22:29:00.001+10:00

Having recently brought a couple of robotics books and subscribed to Elector, I have whetted by appetite at doing a vehicle based robotics project (having designed UAV's and submarines). I guess after the vehicle there still is boats, hovercraft and choppers, but while I'm on to vehicles, I have two different designs I want to create.
1) A basic line following robot (using a couple of IR LED/reciever pairs will follow a black line of electrical tape of a white surface). This will be more of a proof on concept - small scale project, just to get into the swing of control systems again. I envisage using a PID control algorithm to keep things on track.
2) A larger more robust robot fitted with a xy adjustable video camera - transmitting to a remote location. Hopefully I will be able to experiment with inertial navigation (augmented with the GPS module from our UAV) and will have a bit more expertise in mechanical construction designing driver mechanisms. I'd be nice to also have an adjustable height camera (can extend up to look over barriers) and possibly some sort of audio link (so I can communicate with people the robot sees). I'll also be a good excuse to get the welder out and build something cool.

Does Richard Dawkins exist?

2007-09-20T21:20:00.000+10:00

I recently came across a very amusing little parable regarding the existence of Richard Dawkins. It takes a hyper-sceptical approach to the existence of this 'so called Richard Dawkins figure', with the 'scientist' being interviewed doing an exceptionally good takeoff both of Dawkins voice and his arguments. I strange side point to this is a book 'The Dawkins Delusion' is mentioned as part of the parody, and this book now exists - I'm currently reading it. It was written by and Oxford professor as an answer to many of Dawkins ridiculous tirades against religion.

XY Servo control

2007-09-16T16:09:00.000+10:00

After taking a look at some of the video of defconbots and a guy who has mounted an x-y head controlled camera on his model plane - and uses it to fly, I thought I should get into the action.
One place I would particularly like to use this is on the aft camera on the ROV - allowing surface controlled panning and tilting so we can see what is around. Basically two servos are used (one for each axis) and a laser is used in my experimentation (my miniature video camera is currently refusing to behave). At this stage this is just a proof of concept design that will be adapted for bigger and better things.

Mini Heli - a marvel of micro engineering

2007-09-13T20:20:00.000+10:00

About 3 months ago one of the engineers from work brought in his miniature helicopter and drew quite a crowd in the office. A couple of weeks later we each had our own (thanks to eBay ~$20) and have had heaps of fun. They are quite resilient and simple to repair (I've been doing a fair bit of that). This week another engineer brought his 'combat helicopters' in. These each have an infrared transmitter and reciever, where the goal is to 'shoot' the other chopper out of the sky. When a chopper registers a 'hit' the engine stops and it falls to the ground. So far I have 3 kills and have only been shot down once. This was originally an idea we had for our final year engineering project - using planes. We had a couple of things working against us - only one plane, and only one pilot - the UAV project turned out to be somewhat more practical.

Batch script: date/timestamped backup

2007-09-12T21:47:00.000+10:00

One of the early batch scripts I wrote was to backup whole folders. This was particularly used during my Computer Science Honours research - where I wanted to ensure that multiple regular backups were made - particularly of documents and reports.
The script extracts time and date data from the 'Date /t' and 'Time /t' DOS commands, rearranges the order to have a date/time stamped folder that can be sequentially ordered, and then copies everything of a particular directory or directory into this new directory. Using the command line functions on WinRAR similar functionality is possible, with compression and fewer lines of code. WinRAR isn't free (although it continues to let you run it after the trial has expired), but provides good command line support. Since I can't currently find the WinRAR batch files I wrote I have provided the standard batch file below:

@For /F "tokens=2,3,4 delims=/ " %%A in ('Date /t') do @(
Set Day=%%A
Set Month=%%B
Set Year=%%C)
@For /F "tokens=1,2,3 delims=: " %%A in ('Time /t') do @(
Set Hour=%%A
Set Minute=%%B
Set TOD=%%C)
SET DateStamp=%YEAR%-%Month%-%Day%
SET TimeStamp=%Hour%.%Minute% %TOD%
cd\
cd backup
mkdir "Backup(%DateStamp%- %TimeStamp%)"
xcopy C:\Checkout\Project\*.* c:\backup\"Backup(%DateStamp%- %TimeStamp%)" /E

An example folder created by this script was: "Backup(2007-09-12 - 09.59 PM)"

DOS isn't completely useless

2007-09-07T16:18:00.000+10:00

This is somewhat in response to a Linux supporter friend of mine that said a fresh install of Windows was "completely useless". Having used Linux off and on - the issue here is getting a fresh install of Linux - fairly simple with a fresh install of Ubuntu (though the wireless card still doesn't work which he admitted to being a Linux-centric issue), but it used to be an enormous pain with older versions - I wasted several weekends getting my old Linux box setup.
Back to Windows then. A couple of years ago I got into writing DOS batch files - mainly for doing backups and the like - and when coupled with something like WinRAR they can provide automated, date/time stamped, compressed backup. Since hard drive space isn't a huge issue at work I have set scripts to make a copy of all my important folders date and time stamped. We do use code versioning, but on a couple of occasions doing this has really got me out of a mess - forgot to check something in, or a PDF or Word doc which doesn't respond well to binary diffs. I will post that code soon, but first I wanted to show a really simple FTP uploader. It requires nothing more than a standard Windows build. It's not very secure (passwords are stored in plain text - though in FTP they are transmitted in plain text anyway). It is very functional though as when created as an icon on the Windows desktop - when a item is dragged and dropped onto this icon it will initiate the script and automatically upload the file.
Below is the script:

@echo off
> c:\script.txt echo open ftp.yourlocation.com
>> c:\script.txt echo username
>> c:\script.txt echo password
>> c:\script.txt echo cd Uploads
>> c:\script.txt echo send %1
>> c:\script.txt echo bye
ftp -s:c:\script.txt
del c:\script.txt

The script creates another file to execute (script.txt) which is deleted when the script terminates. You replace the username and password for the ftp username and password. "cd Uploads" refers to the destination directory - eg. cd Upload/Robert/pictures. "%1" refers to the command line argument supplied to the script from the drag and drop function.
Very simple and functional. I personally use this for uploading sermons from church onto the Church website where some cleverly crafted PHP interprets the sermon names and displays them to the screen - all without me having to manually FTP in - marvellous.

Propellers formed

2007-09-06T16:01:00.000+10:00

Using a Stanley knife and a file I recently took to some 4.5" model aeroplane propellers to make them more suitable for ROV work. Because they density of water is much high than that of air long propellers would create significant drag on the motors which according the ROV boards I have been frequenting at least will cause them to die prematurely.
2cm was removed from each blade of the propellers - turning them into 2.9" or 7.4cm propellers.
Minor differences in the thrust produced by each propeller will be handled in software - where PID stabilization algorithms - coupled with a gyro should be able to even out the thrust produced by each propeller - individually driving each one through a PWM controlled H-Bridge.

La Trobe Open Day 2007

2007-08-27T13:43:00.000+10:00

Yesterday was the Open day at La Trobe Uni, which though I'm not a student at any more I took a very active part. I gave two presentations regarding electronic engineering, which can be found here, and had on display the UAV and the new ROV project. Some of the people coming around looking at the ROV asked where we purchased it from or had it fabricated which I took as a huge compliment and was able to tell them I built it myself from the ground up. It was also really great, though tiring to talk to potential students and find out some of the things they were interested in. Several were really enthralled and interested in robotics, mirroring my own recollection of when I attended open day in their shoes in 2001. I remember I questioned one of the guys about creating a robot-wars style project for the final year project - to which he replied "it's possible, but the students probably wouldn't want to see a years work cut to pieces in a matter of minutes".

Vertical Thruster Mount

2007-08-25T10:32:00.000+10:00

The vertical thruster mount is now completed. This mount holds the downward pointed thruster in position which will allow the ROV to dive and surface. The thruster mount consists of 6 different PVC components, which are all cemented together. Apart from securely holding the motor and directing water flow, this mount serves to stabilize the main fuselage against the base - ensuring it remains both centred and level.
The stages of assembly can be viewed here.

Cleaning off PVC cement

2007-08-25T08:24:00.000+10:00

One issue I have come across in making the ROV look especially pretty is excess PVC cement. It is a pain to remove, doesn't paint over well (in yellow at least) and runs everywhere when liquid. I know there are some PVC cements available that are a little more friendly to work with - but I don't currently have them.
One quick method I have come across (though experimentation) was using a wire brush attachment on a dremel like tool - it removes the PVC cement rather quickly - though it does expose a rather interesting property of the cement. When bonding the cement eats into the PVC. When the cement is removed it leaves small pits/valleys where it has eaten into the PVC. Following this up with some sanding before painting is highly recommended.

Best Thesis

2007-08-18T20:14:00.000+10:00

One minor update on the UAV project - Wade and I won best final year engineering thesis (this comes about 6 months after the project is all handed in and finished).
I have updated the UAV site with both the thesis and project plan.
UAV Site

We all live in a (small) yellow submarine

2007-07-29T20:49:00.000+10:00

The ROV just had a couple of coats of paint and has come up rather nice.
For those keen in photography the photo of the ballast tank was taken with F32 - to get quite a reasonable depth of field.

Flexible ROV cabling system.

2007-07-27T19:17:00.000+10:00

To provide maximum flexibility for the ROV cabling and allow different connections to be simply added and removed, I have devised an ingenious modular cabling system. This way any cables - from optical, coax or Ethernet can be swapped over in a matter of seconds and are easily removed for travelling.
The system involves screw ports on the side of the hull were different cables, encased within screw plugs can be added or removed. Since these are separate from the main back screw-on panel, the cables can be screwed in, then plugged in (to avoiding twisting) and finally the back plate can be screwed on.

ROV webpage

2007-07-24T23:22:00.000+10:00

I have now put together an ROV page, which among other things will contain a pictorial summary of the progress of the project thus far.
The page is here.

ROV "Bathtub Test"

2007-07-23T07:30:00.000+10:00

Yesterday I filled up the bathtub (from rainwater - hence the sediment in the tub) to test out the ROV's buoyancy and thruster power.
The tests indicate that an additional 3kg of weight it required to make the ROV neurally buoyant.
Also one thruster (show in the video) seemed to be sufficient to push the ROV along nicely. With two thrusters providing differential control the ROV should be able to have a semi-decent speed.
My initial plan was to use a further two bilge pumps to control depth (one pointing up, one pointing down).
The tests seemed to indicate that the bilge pumps I was using weren’t sufficiently powerful to perform this function. I now plan to use one pump fitted with a propeller (alike the thrusters), mounted on the bottom of the ROV to allow the ROV to dive and surface.

Converter Pictures

2007-07-22T15:49:00.000+10:00

Here are some promised pictures of my line-input to mic converter.
The circuitry was encased within hot glue (pic2) and was then covered with heatshrink (not shown). The circuit used was from: here

Title: MacGyvering my line input

2007-06-30T22:21:00.001+10:00

One problem I have previously noted with my laptop is the absence of a line input port. The after spending some time to Googling and consultation with a fellow engineer from work, I built and tested a small circuit consisting of only three components to convert the line-input signal into a mic-input signal. The circuit consists of to resistors which form of voltage divider providing approximately 20 DB of attenuation of the input signal. It also a includes a capacitor which the effectively removes any DC offset those introduced by the line in stage. I have already used this device when connecting out my video camera to the computer to extract some audio from a production I was putting together. The one limitation I have identified is that it only works as a mono input as contrasted that with the stereo line input provided on most computers. This however should serve well as most of my recordings of from conferences and speeches. Another recent development is my acquisition of the first two seasons of MacGyver on DVD. Soon I hope to provide a photo and circuit diagram.
This is a series of grew up with and enjoyed very much a child and am now more aware of some of the limitation of the various hacks he performs as an adult engineer. Funnily enough of the last conference I’d attended (church camp) I remembered this recording limitation of my computer a little too late, and on the spur of the moment thought to record the presentations directly onto my MP3 player – something in the best traditions of MacGyverisms.
On another note, this post was almost entirely in the multi its but spoken to using some text to speech software that I’m currently trialling. So… debate over all words completely out of place they can blame on the speech to text engine.

ROV Porthole

2007-06-11T10:39:00.000+10:00

One feature that almost goes without saying for a ROV is a video (+ possibly still) camera. Imagine being able to hover around reef systems, or around the piers and see all the little fish swimming around. To make this possible a viewing hole must be installed which will allow the camera to have a view of the outside world.
I made the viewing hole from 4mm Perspex salvaged from an old fish tank. To get the round shape (which fits in the groove of the endcap - see pics) I embarked on the following process.
1) I covered the Perspex in contact on both sides to avoid scratching the surface
2) I scribed the design onto the Perspex using a circle I generated in MS Word and a hobby knife
3) I used a hand jigsaw (like a mini hacksaw) to approximately cut of the perplex. I had wedged the Perspex between the table and a piece of MDF - thanks to Adam for that suggestion.
4) I clamped a file into my bench press so that it made an angle with the jaws of 90 degrees. Using the jaws as a guide, I spend the next few hours shaping the Perspex to meet the lines I had scribed - regularly checking if it actually fit.

After drilling the 75mm hole in the end cap I affixed the Perspex using silicon specifically targeted at watery applications (recommended for aquariums and the like.

UAV Wrapup

2007-06-10T14:22:00.000+10:00

Ok, the interview of the century is now on the web:

Stove Writeup Final

2007-06-09T22:03:00.000+10:00

After half a dozen or so tests I have found a simple aluminium stove combination which works nicely.

- Drill three 2mm holes clustered towards the centre of one half
- Use a 0.8mm drill bit to drill the jet holes - I have been drilling about 10 in a pattern which is optimised for using a kidney cup for cooking
- Cut both cans to about 2.5cm height
- To ensure it fits together nicely put two large creases in the can that fits on top - at the top of these creases drill a small hole to prevent pressure build up

All going well I'll be testing these stoves out at Lerderderg Park in a weeks time.

PHP is your friend

2007-06-09T17:46:00.000+10:00

Recently for a website that I manage I wanted to make a section where details of the files within a folder are dynamically displayed, showing their size along with some formatted details garnered from the file name (date, speaker and topic).
For these sort of exercises PHP is really handy and my first preference - possibly as I grew up with C and the formatting is a little similar. It has some really neat file parsing options - like fill an array with all the filenames in a directory we go:

$dir = "./Sermons/Sermon_Audio/";
$dir_handle = opendir($dir);
$i = 0;
while (false !== ($file_name = readdir($dir_handle))){
if ($file_name != ".." and $file_name != ".") {
$dir_array[$i] = $file_name;
$i = $i + 1;
}
}

To sort them just do
rsort($dir_array);
or
sort($dir_array);
depending if you want to sort in reverse or not.

It has some great splitting functions to tokenise strings like to remove the file extension:
$removed_extension = explode(".", $dir_array[$i]);

And reading the filesize is dead easy (the 1024*1024 is to convert the size to MB - the function returns filesize in bytes)
$file_size = filesize($dir . $dir_array[$i])/(1024*1024);

ROV Introduction

2007-06-08T20:17:00.000+10:00

Recently I have been busy working on an ROV (Remote Operated Vehicle), which is basically an underwater tethered robot. I had the idea around the time of the inception of our UAV project, but with little knowledge about submarines and a fair knowledge of aircraft we decided to go for the UAV. The idea has therefore been around for a while - but the motivation was somewhat lacking - until talking to my project supervisor the idea of running a ROV project for 2008 was raised. My role would be the mechanical design and supervisory for the electronics - supervising a team of final year students who would do the control and communications systems.
I figured this was more than enough motivation to start work on the ROV and so over the next little while the mechanical design steps and some ideas about how the electrics will work will be found here.
One background source I found particularly helpful was "Build Your Own Underwater Robot and Other Wet Projects by Bohm, Harry" which provided some very useful background info and some basic design and control ideas. Having adapted some of these my design is for a neutrally buoyant ROV, with two rear bilge pumps (converted to drive propellers for proportional control) and two angled bilge pumps to provide reversing, surfacing and diving motions.
The basic framework is built from 15mm PVC piping (shown in the picture).

Fix-it 5: PCMCIA woes

2007-06-02T17:18:00.000+10:00

One annoying drawback with my current laptop (an otherwise excellent T43 Thinkpad) is it doesn't have built in Firewire (or a sound line in for that matter with is also annoying). Since I'm doing a fair bit of video work I decided to get a PCMCIA firewire card to overcome this hurdle - so onto eBay. The $18 car that I got looked kind of cheap (they even spelt insert wrong on the card label - I'd rather not inset the card). Anyway to cut a long story short the connector on the card wasn't straight and so bent the pins within my PCMCIA socket - Grrr.
On the Lenovo site they have excellent service manuals which aided me in pulling apart the laptop and straightening things out :).
A couple of days later I purchased a card from Centrecom, though it was double the price, it was of much higher build quality and worked perfectly! Excellent.

Fix-it 4: ADSL connection

2007-05-26T20:41:00.000+10:00

Another simple job I had was out in Caulfield - about an hour from home, but a tolerable deviation from work - so this was a job on the way home from work from work albeit in an indirect way.
The problem: The phone and fax in the bedroom don't work, but the phone in the kitchen does. Previously there was no ADSL filter in the bedroom and it worked OK up till a couple of months ago (they have had ADSL for years) - this shouldn't really be the case but it was - possibly they didn't notice the noise and the exchange was recently upgraded to ADSL 2. The filter that had been installed when this problem started was simply installed incorrectly - the fax was plugged into the phone output - ok there, the phone was plugged into the ASDL output - a no-no. After putting in a double adapter and a second filter that problem was quickly solved. Besides my 'consultancy fee' I got a free dinner - bonus!

Fix-it 3: Computer recovery

2007-05-26T20:36:00.001+10:00

I was recently called out to finish off the final stages of a computer reinstall. Apparently there were problems with the video card drivers as well as the ADSL modem. First the video card.
After consulting the manuals the appropriate drivers were downloaded and installed - at which point the computer promptly rejected them. After opening up the computer it quickly became apparent that the manuals were from a previous computer - doh! After downloading the correct drivers relating to the actual hardware it was all sweet. To get the modem working the ISP software was promptly installed and was off and away.

Fix-it 2: Laptop power connector

2007-05-08T18:12:00.000+10:00

A good friend recently asked me to take a look at his laptop – it seemed that it would intermittently charge. Having had a look at the power connected it was revealed that the wires were a little frayed (and had been previously patched up) so I assumed this was the main problem. After replacing the connector with a brand new one, the same behaviour manifested itself – wiggling the connector in certain positions would allow the laptop to charge – and others would result in nothing. Time to open up the laptop – a job not for the faint hearted as getting to the power connector basically means removing everything (including the keyboard, screen and heaps of screws). Having got to the power socket on the motherboard it was clear that it needed replacing – cracked in several places (see pic) and intermittently making and breaking the power connection as the plug was wiggled. A new connector and some fancy soldering resulted in a most satisfactory fix.

Faster ... and more efficient

2007-05-04T22:15:00.000+10:00

Having gone through quite a few cans in the past week testing various alcohol stoves I recently built a variant of the penny stove. Rave reviews had been written about this stove and they seem to be well founded. In tested it brought by 500mL of (uncovered) water to near boil in about 5 minutes, and used significantly less fuel than the previous version. It looks like the penny stove is going to be the one I'll be taking out camping. The only hassle is to ensure there is a good seal between the penny and the can - otherwise all the primer fuel runs out into the base. This stove is actually easier to built - no rivets required (I tried putting rivets in the side - just to ensure it stays together, but because of the increased pressure flames come out of these - so no need to worry about rivets).
It should be noted no snails were hurt in the testing of this product.

Alcohol Burner/Stove

2007-04-29T16:18:00.000+10:00

In a mood for building something I thought I would try my hand at building an alcohol stove (from Pepsi cans). This was based on the design found here. Halfway though the construction I found what seems to be a much more efficient burner, but as I was already engrossed in this one I pressed on.
My construction varied - mine uses no tape, and features small pop-rivets to join the middle separator ring together.
The results in non-optimum (the pot is uncovered and is sitting too high) was that it took 50mL of Metho, approximately 8 minutes to boil 500mL of water.
The improved version seems to be much more efficient (31.9mL of Metho to boil 945mL in approximately 8 minutes) - I might build this 'penny' version next, along with a pot holder. It would seem that Americans call Metho denatured alcohol (which was proving most confusing at first as I’d never heard of denatured alcohol).

Fix-it 1: Violin mic

2007-04-28T13:40:00.000+10:00

Recently at church there was a little accident relating to a musician getting tangled up in the cable from a violin pickup mic. This resulted in an intermittently working pickup - due to a break in the rather thin cable running to the mic.
The fix was relatively straight forward and cost effective.

Simply getting a new length of cable ($2 worth) and a new 6.25mm mono plug ($0.85 worth). The old cable was desoldered from the pickup and the new cable soldered in - easy!

Fix-it Introduction

2007-04-28T13:32:00.000+10:00

Being an engineer with a background in both electronics and computers ensures that I get plenty of questions from family and friends - particularly when something breaks down - (or breaks!). So I can keep a record of things I have successfully fixed, for educational reasons and also to give me some content for this journal. I hope to post a weekly fix-it instalment - this will of course depend on how often things break down - but based on experience this is not entirely unreasonable.

Surefire is sure-bright!

2007-04-26T22:15:00.000+10:00

About 12 months ago I purchased a Surefire 6P torch. Not only are these things about the toughest torches I have ever seen they are also exceptionally bright. This was borne out on a recent beach mission up at Halls Gap I was volunteering on.
Half way through a concert night and just before an illusion act someone tripped over a powercord - which meant we lost all sound and lights. It looked like it would take a few minutes to restore lights so I went forward with the Surefire and used it to light up the stage area - which it did exceptionally well - providing enough light to ensure the performance was easily seen.
These torches aren't cheap - mine set be back in the order of $80AUD - but for the quality and brightness they are well worth it!

The Carnage!

2007-04-26T20:24:00.000+10:00

After several months of relative inactivity on the UAV/flying front I decided ANZAC day was the perfect day to get back into it. The weather was perfect for flying - hardly any wind, and lovely and Sunny - but not overly glary.
The original plan was to first take out the UAV and (under complete manual control) put it through its paces. I was really looking forward to this, as when we were flying with all the extra hardware onboard it was a little laid down and was really sluggish - I was really looking forward to doing a bit of aerobatics and really opening up the throttle. But those plans went amiss - it seems I completely destroyed the motor speed controller/BEC circuit in the latter stages of our project - now the BEC doesn't work at all and the motor speed controller is stuck at full throttle - a replacement module is on order from hstore.
In the mean time I managed to switch over my controller from mode 1 to mode 4 setup (the cause of at least 4 crashes).

Failing the UAV - I still had the heli which I'm trying to learn how to fly. The first flight was uneventful - hovering a foot or so off the ground - gently hovering up and down. Spurred on by this success I charged up the battery and promptly did the chopper a whole lot of damage - 5 seconds into flight. A foot of the ground the chopper banked left - the rotor clipped the ground - flowed by the tail. Total damage: tail boom snapped in half, damaged rotors, missing tail gear. I have now order the spare parts and a new (different) chopper. Hopefully this will be easier to learn to fly in.

Tilt based mouse replacement

2007-02-18T22:34:00.000+11:00

Over a recent online discussion with Wade - we formulated a brilliant plan for combating RSI (something we coders can suffer from at times). Basically the plan is to use a 2-axis accelerometer as a tilt meter (which works well if you are fairly stationary as it responds primarily to gravity). This would be connected through some wireless interface (possibly BlueTooth) back to the computer (although the initial prototype will probably be wired). As you tilt your head forward and back, the mouse cursor would move forward and back - likewise with side to side. I'm very pleased with this idea and hope to show it off at work soon (along with my other half-dozen projects that haven’t quite gotten off the ground yet).
Besides normal day to day use, I think this would work particularly well for first-person games.

Hysteresis

2007-02-16T19:14:00.000+11:00

Hysteresis is a term used to describe (in electronic control systems at least) the control descison being dependent on past history, accounting for a reaction time to changes induced by the controlled equipment. An example in point is a temperature controller I'm currently planning out. It is to be to ensure electronic equipment is kept reasonably cool - using a fan driven by a microprocessor which uses a small IC temperature sensor to determine when the fan needs to be run and when it can be turned off.

A simple way to do this would be as follows (shown in pseudo code):

if (temp > 40) then
   fan = ON;
else
   fan = OFF;
end if;

Though this would work and is very simple it had a rather undesirable affect. That being that the temperature will tend to oscillated around the 40 mark with the fan continually being turned on and off. The alternative accounting for hysteresis would look something like this:

fan = OFF;

while(1){
   if (temp > 40) then
      fan = ON;
   else
      if (temp < 35) then
         fan = OFF;
      end if;
   end if;
}

In this example the fan won't turn on until the temperature reaches 40, but won't turn back off again until it drops below 35. This dampens oscillations and recognises the non-instantaneous nature of the temperature with reference to changes in airflow.

It should be noted that this is a very simple control algorithm, but should provide reasonable operation. More sophisticated algorithms such as the PID's used in my UAV project allow much better control allowing varying rates of change (rather than simply off and on).

Part of the reason this project has come about is that our DVD player recently overheated, causing several electrolytic capacitors to explode. The area where the new DVD will be is still fairly hot, particularly during Australian summers (which often get up to 40degress C). Hopefully soon I'll have some schematics up - the target device at this stage will be a PIC 16F88 (the one with the inbuilt ADC).

An interesting and viable approach to GPS photo tagging

2007-02-14T21:33:00.001+11:00

During research for this project I came across this product. Basically all it does it take a GPS sample every 15 seconds and store this in memory - date and time stamped based on the GPS time. When connected to the computer some cleaver software compares the time when each photo was taken to the GPS measurements at that point and inserts the relevant GPS data. I'm thinking this is quite a viable alternative and since I already have most of the hardware this is the path I'm looking at travelling along.

The plan in short:
- An AT-Mega128 will be used to read in GPS data from my GPS receiver at say 10 second intervals. It will strip off most of the unneeded stuff - just keeping the time/date stamp, the lat, long and alt.
- The micro will then write this data to an SD memory card though a DOSonChip interface
- I will probably use some cleaver perl scripts to parse the photos and correlate their time taken with the GPS logs. From there the script will insert the relevant GPS data into the Exif header of the jpeg files.
- One further enhancement would be to make the GPS unit nice an compact and mount it on the hot shoe of the camera. That way each time the camera takes a picture, GPS data could be logged onto the SD card. The same scripts would be used to match up this GPS data with the specific photographs. Though this approach may be more elegant - it seems to be less practical (extra stuff hanging off the camera - and wouldn't be adaptable - ie. if I wanted to use it onboard one of my aircraft) so possibly I will go for the first option, but add some additional trigger points which could be wired to a wireless transceiver at a later stage.

Digital Rebel!

2007-02-14T19:35:00.000+11:00

Digital Rebel!

I recently purchased the Canon 400D (or US name – Digital Rebel XTi – which sounds heaps cooler). I took this on a hike to cradle mountain and it turned out some stunner photographs (like the photo of Barn Bluff shown right)

Having said that there are two things I’m looking at making to supplement it.

- A remote shutter control (either wired – very easy, or wireless – a little pricier). This seems pretty simple from some schematics shown around on the web and should mean that I won’t introduce ‘shakes’ to the camera when taking pictures.

- Some method of tagging GPS coordinates with the camera. I recently saw on the Nikon DSLR cameras which had a ‘shoe’ the GPS could mount on to perform this function – as yet it doesn’t seem Canon offer this functionality. One method would be to remove the memory card (CF in this case) and plug it into a writer each time the GPS tags are to be added – this wouldn’t be too hard, but is more than a tad inconvenient. Another method would be to interface a microcontroller with the USB interface. One problem here is the 400D doesn’t seem to allow Windows to mount the memory card directly, but rather uses a WIA protocol, which on the outset seems to be mainly one 1 – Doh!

Possibly I will just have to do it in software back on the computer for now – an activity which seems to be gaining in popularity.

How many satellites can you see?

2007-02-13T21:25:00.001+11:00

During our engineering project Wade and I noted that our GPS receiver was capable of tracking up to 12 satellites simultaneously, as compared to some GPS receivers which could track up to 20. In most of our field tests the best we achieved was about half a dozen (at the time read from my Magellan 315 - not directly from the receiver). Well on top of Cradle Mountain (~1550m AMSL) I was consistently receiving data from 9 different satellites - not bad! Possibly we could do a little better on a mountain range closer to the equator.

Finally a cool use for my GPS

2007-02-13T21:23:00.000+11:00

I have had my GPS (Magellan 315) for over 4 years now, and have realistically hardly used it (and never had to rely on it) in that time. It has gone on every camping/hiking trip (including Cradle Mt) and has been cool to compare Speedo measurements - but other than that the usage has been somewhat trivial.

That is until I was introduced to Geocaching. Basically one signs up at http://www.geocaching.com/

After signing in you type in your postcode and see what hidden caches are in your local area. You punch in the long and lat into your GPS and find the secret cache.

So far I have found one - out of two trips (The first trip being successful - the second turning up nothing).

One word of warning I figured out the hard way - ensure the GPS Datum is set to WGS84 - otherwise you can be hundreds of metres out.

Google Maps (www.maps.google.com) is also your friend - simply pasting in the coordinates (eg. S 37° 42.893 E 145° 08.879) will take you to the surrounding area with a map.

Bright ideas

2007-01-06T13:29:00.000+11:00

One qualitity that I'm constantly seeing in other engineers is their ability to continually come up with new and interesting ideas for various projects - I guess I'm not an exception to the rule then.
One idea was prompted by my recent week spent over at beach mission. Basically there is one gave were we have to try and determine the relative sound intensity of the children. We could manage to do this by ear - but it could be heaps cooler building a gadget to do so. So project 1 is a simple sound level metre. It would use a small electret mic condenser which is sampled by a microcontroller every 10ms or so. An array of LEDs could then be used to display a moving average of the sound level - say every 250 to 500ms. A button could also be included to allow the maximum sound intensity for a period to be displayed.

The second project can be found here: It is a centrifugal based BB launcher. Since I'm currently waiting on parts for both the coil launcher and air controlled launcher - this could be interesting in the mean time.

Work + Websites

2007-01-03T21:07:00.001+11:00

I just started my new job as an electronic hardware design engineer mid-December. It' s rather unusual still not being considered a student - rather an engineer - the real thing. Cool and wonderful. At the moment I'm learning Perl - which looks really useful for scripting - and something else I can add to my business card - yippee.
I'm currently toying with two interesting projects - they are really different approaches to the same project - a computer controlled coil gun and a computer controlled air gun. Both are quite harmless with an effective range in the order of a few meters. I'm looking at probably a serial connection which will interface with a microcontroller to control some servos providing x and y directional capabilities. At least one of these is on my to-do list for 2007. I'm also looking at using a similar remote controlled servo step at church to remotely control a video camera from the AV-Desk.
The final piece of news I have is that now I have my own domain name. www.rross.com.au
This site incorporates both a technical and a faith aspect to it - both are under heavy development.

A $3 helicopter landing gear

2006-11-02T21:55:00.000+11:00

Having recently acquired a model helicopter – I have learnt that the first important skill to master is hovering. Generally the way this is done is by attaching a trainer landing gear to the base of the plan – this stops you cutting up your props when you pitch or roll the chopper too much. Unfortunately the model I purchased didn’t come with a training landing gear – so I decided to make my own – with a total cost of around $3 (compared to the >$15 models for sale it stacks up quite well).

Equipment required:

- 4 ping-pong balls (purchased a pack of 6 for $2.99 – Rebel Sport)

- 2 metal coat hangers

- 1 drill, 1mm drill bit

- 4 small cable ties

- Heavy duty pliers

- Electrical tape

Method:

1) Straighten out the coat-hangers and cut to size (for me 70cm suits quite well)

2) Drill a hole straight through each ping-pong ball so it comes out the other side

3) Thread 2 ping-pong balls onto each strip of wire,

4) Bend up the last 5mm at the ends of the wire to an angle of 90 degrees

5) Move the ping-pong balls to the ends of the wire and put ome electrical tape over the bent wire to hold it in place and prevent scratching

6) Cross the wires over and attach to chopper with cable ties.

7) Put a small amount of electrical tape into the centre of the crossover to keep them centred with respect to each other.

Chopper Flight 1

2006-11-01T15:19:00.000+11:00

It would seem that helicopters are slightly more difficult to fly than their fixed wing cousins. Basically I have flown the helicopter for all of 5 seconds. It began to bank slightly (about 1m off the ground). I reduced the throttle (a habit from fixed wing aircraft). The chopper hit the ground with a thud. In the movies when helicopters crash (which is about every movie with a helicopter) parts go flying off everywhere - well the same is true for model helicopters - myth confirmed!
I managed to find the tail rotor 5m in one direction and the vertical stabaliser 5m in the opposite direction. Currently I'm missing the tail rotor drive gear. I also need to work out how to balance the props properly - as at the moment they are unbalanced and I'm unable to achieve lift-off.

A view from the air

2006-10-31T19:18:00.000+11:00

Ok, my next photo is up to be voted on. This was on of the photos taken onboard the plane at an altitude of about 100m. If you are impressed (you should be) please vote for the photo.

What does Simplex (and half duplex) really mean?

2006-10-31T12:13:00.000+11:00

In communications engineering there are three basic forms of communication:
- Simplex
- Half-Duplex
- Full-Duplex

The last of these terms (Full-Duplex) is probably the only clearly defined standard that everyone agrees on. Full-Duplex is where both stations on the communications link can simulatneously (or seemingly simultaneoulsy) send and receive data - like when you are using a mobile phone.

Simplex and Half-Duplex are where the problems come in. It doesn't help when the major communications standards organisations can't even agree on what they mean. For simplex the ITU definition is where signals flow in only one direction at a time. The ANSI definition is where signals flow in one direction - period!

For Half-Duplex the definitons are:
ITU: This seems to be the same as the simplex definition (although strangely according to wikipedia the ITU possibly define half duplex as the ANSI simplex definition - which makes no sense at all)
ANSI: Signals flow in only one directon at a time (i.e. the ITU's definition of simplex)

So which is correct? Well it really depends on what you are studying. I'm currently completing two final year communications subjects, with different lecturers choosing opposite definitions. I guess both are right in a silly sort of way - so much for having standards.

Laptop

2006-10-31T10:05:00.000+11:00

After constant jeering (mainly from Wade) and frustration about the limitations of my current (5 year old laptop) I have taken the plung and ordered a new Thinkpad T43. It is selling at a really super deal - typically they retail for $3000 - but direct from IBM/Levono they are only $1199.
So I've just done the transfer and should have my new computer in a week or so. Unfortunately it is not the optimum configuration that I was after:
- It has a parallel port (I consider this to be a waste of space)
- It has no serial port - I use serial extensively for programming microcontrollers. No worries I got a USB to serial converter of eBay for $11
- It doesn't have firewire (I can get a converter for about $20)
- It also lacks built in Bluetooth. I do have a USB bluetooth dongle, but I noticed that on eBay you can get the IBM internal BT modules - that can wait I think.

Anyway, I'm really happy with an amazingly cheap deal.

Chopper data logging plans

2006-10-27T14:02:00.000+10:00

I have been thinking up some exciting plans for addon's to the chopper. Besides the power upgrades I have already hinted at (brushless motor, LiPO batteries), I'm also thinking of creating an ultra-small and lightweight data logger. In many ways a minatuired version of our project without the flight control side of things.
Here are is my current wish-list:
- SD card logging (Using a tiny little IC from Sparkfun)
- GPS reciever (The actual data which will be logged - using the reciever from our last project)
- A control switch - that can be used to drive a digital camera (possibly through an unused channel on the radio controller
- A Tiny digital still camera to record data on (eBay have some rather neat and tiny cameras)
- I still have the little wireless video camera to take motion clips with

A separate edition which would be cool (once I'm a profienct pilot) would be to fit the plane out with LED's for night flying. I'd need some bright landing LEDs, and some to indicate direciton. Possibly some on the rotors would look great too - I'll just wait for all the UFO sightings to be reported.

When this is all bundled together I should be able to quickly transfer it between different craft (planes, choppers, cars) and log whatever I need to.

Help me win a camera, and win $50 in the process

2006-10-27T13:35:00.000+10:00

Canon (Australia) is running a photography competition where each week one photograph is awarded with a new digital SLR camera. Since the photos on their website are only tiny - I thought I would upload it here so people could get a better look. This photo was taken during a hike in Tasmania I was on in January.
If you vote you go into the running to win a $50 cash prize. Good luck.

Totally Wild and a Chopper

2006-10-26T18:47:00.000+10:00

Yesterday Wade and I had several interviews filmed for Totally Wild (a nature and educational show showing on channel 10). The whole process was really fun and will be my first apperance on TV. The weather wasn't too favorable towards flying - so we provided some of our flight footage taken earier on (hopefully they don't use the one of the plane homing in on Wade - who was filming at the time).
With all that excitement I decided to buy myself a chopper. These days they have some small electric choppers on eBay going for under $200. Once I get some experence up I plan to replace the stock battery (NiMH) with a LiPO, and replace the brushed motor with a brushless motor. This should more than double the flight time and give me heaps more power. But first, I'll have to learn to fly the chopper - I'm quite used to fixed wing aircraft so hopefully it won't take too long to adjust. The chopper is a dragonfly walkera 22e.

Tuning performance flight time

2006-10-23T21:41:00.000+10:00

While doing some research into flight performance and handling I came across a great simulator - for simulating paper aeroplane flights
My current record is 85.1885m using Angle = -12, Thrust = 40, Elevator = 8
See if you can beat me

Flying not so high :(

2006-10-22T20:11:00.002+10:00

After ironing out some of the kinks with the bearing PID - which is the bearing autopilot today we went off flying. Unfortunately by the time we had ourselves all setup there was a growing gusty wind. This flight was conducted on an oval in Bundoora which is linked to two other ovals. Our normal ground - the La Trobe sports grounds was in use by two different cricket groups - they had divided the oval up between themselves.

Unfortunately this flight was far from spectacular. After switching over to autopilot, the autopilot (admittedly underdamped) began tracking the specific bearings that were had chosen. After about 10 seconds major mechanical failure ensured when one of the wings snapped in half - plummeting our plane to the ground rather quickly. I guess the wind might have been a bit too much. It's really rather annoying as my last few landings have been quite splendid.
A red dot shows the takeoff point - a blue dot shows the landing point.

The flight log can be read here

Flying High 2

2006-10-20T18:16:00.000+10:00

Wade and I took the plane out today to secret testing ground 2, the La Trobe University sports grounds. We flew against some pretty gusty wind but managed to get some good flight data and verify the corrected latitude and longditude values.

Flying high

2006-10-19T22:04:00.000+10:00

Finally most of the bugs have been ironed out of the flash memory card logging software allowing us to go flying around and actually logging the flight data. The Google Earth (TM) picture on the right shows the flying ground (with a red dot marking the launch point).

A log file was downloaded from the plane on landing from the onboard MMC card. One little bug I need to fix is printing the latitudes and longditues as signed longs - not unsigned longs (hence the very large values). But these can be easily fixed.

The data is stored in the following formats (which I created today):

For ADC sensor data:
Format: "$UAVADC,BA:720,TE:323,PR:9,AX:353,AY:453*"
BA = Battery
TE = Temperature
PR = Pressure
AX = Accelerometer X
AY = Accelerometer Y

For GPS data:
Format: "$UAVGPS,TS:1794299271,LA:-22432475,LO:73183416,AL:93,BE:315,RG:1,GG:1*"
TS = Time Stamp (multiplied by 1000
LA = Latitude (mulplied by 60000)
LO = Longitude (mulitplied by 60000)
AL = Altidude (MSL)
BE = Bearing (Degrees)
RG = RMCGood (1 = good, 0 = bad)
GG = GGAGood (1 = good, 0 = bad)

For magnetometer data
Format: "$UAVMAG,BE:321,AX:-224,AY:716*"
BE = Bearing (Degrees)
AX = Axis X value
AY = Axis Y value

And yes - I too was pretty astounded to have got the plane upto around 300m (above ground) - I figured we would be struggling to get 150m

Magnetometres work better when magnets are not sitting on top of them

2006-10-19T17:13:00.000+10:00

A magnetometre is a device which measures the earth's magnetic field in two axis and allows you to work out the direction of magnetic north. It basically allows you to create a 'digital compass'. Our testing involved taking measurements at 15degree increments to allow us to determine the error involved in the measurement (generally a under a couple of degrees) and also appropriate offsets to calculate a bearing measurement. That all worked well - using a compass and the diagram shown to make the measurements.

Using it in the plane is a different story through, about 3 cm above the magenetometre sits the GPS antenna - and in this configuration it gave extremely erratic results. After about 5 minutes it clicked that the antenna has a couple of magnets in the base (designed for car mounting) - when these are removed - unsurprisingly the magnetometre works again.

Need a new set of wheels?

2006-09-29T12:32:00.000+10:00

I have just uploaded my second eBay auction.
Take a look at the auction here - these would be great for a range of mechanical and robotics projects - projects that I just don't have time to go into now.

Clock me up!

2006-09-22T22:29:00.000+10:00

Just yesterday Wade and I were fiddling around with the clock settings for the control board for our project. By default an internal clock is used (generated within the AVR). This internal clock is slower than the external clock that we are using (16MHz) and so had to be changed. Unfortunately changing the clock can be a slightly confusing process - since there are about 15 settings for different external oscillators. Wade picked out one and tried it (with my approval). Note we didn't properly read the data sheet - and so after we made this change everything went dead.
The programmer (ISP) that is used doesn't generate its own clock signal - and since we were using a clock that didn't actually exist we couldn't reprogram to fix the problem. My solution was a fallback one as I didn't have any crystals about. Program a PIC microcontroller to toggle an output to emulate the clock. To do this we had to remove the old oscillator from the AVR board, connect the PIC and then reprogram the fuse bits. This worked a treat - we replaced the oscillator back in and we are in business at 16MHz.
The code for the PIC couldn’t' have been much simpler - and using the internal oscillator on the PIC16F88, I basically had to connect power to the pic with some decoupling caps and that was it. Simple!

#include
#define clockFreq 0x70 //8MHz

#ifdef _PIC16
#pragma DATA _CONFIG1, _CP_OFF & _CCP1_RB0 &amp; _DEBUG_OFF & _WRT_PROTECT_OFF & _CPD_OFF & _LVP_OFF & _BODEN_OFF & _MCLR_OFF & _PWRTE_OFF & _WDT_OFF & _INTRC_IO
#endif //_PIC16

void main()
{
osccon = clockFreq; //Choose internal clock rate
ansel = 00000000b; //all A/D off
cmcon = 00000111b; //comparators off

trisa = 00000000b;//All outputs
trisb = 00000000b;//All outputs
porta = 00000000b;
portb = 00000000b;

while (1){
porta ^= 0x01; //Invert bottom bit
}
}

GPS antenna - unhacked

2006-09-20T14:21:00.000+10:00

Ok, at midnight last night I was working away, testing the UART's on the final board. The strangely the GPS reciever could not pick up a signal at all - it was just refusing to track satellites. The antenna I was using was the hacked down version, where I had removed the case, 90% of the wiring and the base. It seems the base is needed to complete the ground plane - so when this was added back in the GPS picked up the satellites virually straight away and locked on. This brings the weight back up a bit - the moral of the story is keep the ground plane!

OK - no it is Excellent!!!

2006-09-18T19:05:00.000+10:00

After just plugging in the AVR to the computer and clicking program the results are in:

Reading FLASH input file.. OK
Setting mode and device parameters.. OK!
Entering programming mode.. OK!
Erasing device.. OK!
Programming FLASH .. OK!
Reading FLASH .. OK!
FLASH contents is equal to file.. OK
Leaving programming mode.. OK!

Just as I had hoped (at least the good OK's had an '!' following them).
I should note that this was the second shot- the first time one of the ISP-Prog pins was incorrectly connected - a couple of solder joints later and success!

Power - Check, Override - Check

2006-09-16T14:41:00.000+10:00

The last few days I have spent doing one of my favourite parts of the engineering process - hardware design, implementation and testing. You will see the PCB is starting to become populated with various components. The first part to build was the power supply circuitry - as this was fairly robust and nothing else could really be tested without it. Having installed the regulation circuitry for 5V and 3V - these were tested and found to be working well.
Next was the manual override circuitry - After installing all the relevant components I plugged my receiver in and checked what sort of result I was getting. Firstly I tuned the potentiometer to a nice position where moving my control stick in one direction switched to auto and centred or in the other direction switched to manual. So far - so good. Then the big test for this stage was to look at the behaviour when I switched off the controller (simulating a loss of signal) - the circuit started oscillating between auto and manual control every second or so - not a desired outcome. Looking back through my log book (yes these are really handy now - this saved me lots of debugging time) I found I had mistakenly put the wrong capacitor value on the schematic (for the 555 timer). When I changed the value (from 22nF to 10nF) the whole system worked perfectly - that log book has probably already paid for itself in saved time! Soon I'm planning on putting together a tutorial on double sided soldering of DIP terminal connectors.

PCB - Finally

2006-09-13T15:35:00.000+10:00

Today I picked up two very nicely fabricated PCB's (exactly 1 month and 2 days after I submitted them). The finish on the PCB's is extremely professional. Unfortunately my setup at home only allows me to do single sided photo etching - if I can find a supplier for double sided pre-sensitised boards, I might step up to the next level.

Please wake me up

2006-09-11T17:18:00.000+10:00

Over recent days I have been toying with the idea of creating a hardware based WOL (Wake On LAN). The application is an interesting one. I'm setting up a computer in a remote location which is connected to LAN via WIFI. This computer will be used for a estimated maximum of 5 hours a week (mostly on weekends). The computer is about 2km from my house (and on a different network), so it would be nice to turn it on remotely so that I can connect to it from home via remote desktop (or something of the like - after configuring this in the local router). Unfortunately the WIFI standards up to 802.11g don't support WOL (although 802.11n is rumoured to) - unlike most standard 10/100 NIC's these days.
With this in mind I have thought about setting up a small microprocessor connected to the Ethernet port of the computer. This micro could have a real time clock and could trigger the WOL functionality of the computer at predefined times that I have programmed in. How does this work then? Basically a special UDP packet containing a 'magic string' is used to trigger the computer into waking up. Using Ethereal (a great packet analysing program Wade put me onto a while back), I was able to take a look at what these 'magic packets' look like.
Basically it is like:
0000 ff ff ff ff ff ff 00 10 a4 84 5a d2 08 00 45 00 ........ ..Z...E.
0010 00 82 63 f9 00 00 80 11 14 c7 c0 a8 01 03 ff ff ..c..... ........
0020 ff ff 05 eb 2f ff 00 6e 05 b2 ff ff ff ff ff ff ..../..n ........
0030 00 14 85 ea 2a 1e 00 14 85 ea 2a 1e 00 14 85 ea ....*... ..*.....
0040 2a 1e 00 14 85 ea 2a 1e 00 14 85 ea 2a 1e 00 14 *.....*. ....*...
0050 85 ea 2a 1e 00 14 85 ea 2a 1e 00 14 85 ea 2a 1e ..*..... *.....*.
0060 00 14 85 ea 2a 1e 00 14 85 ea 2a 1e 00 14 85 ea ....*... ..*.....
0070 2a 1e 00 14 85 ea 2a 1e 00 14 85 ea 2a 1e 00 14 *.....*. ....*...
0080 85 ea 2a 1e 00 14 85 ea 2a 1e 00 14 85 ea 2a 1e ..*..... *.....*.

Note the sequence 00:14:84:ea:2a:1e which is repeated about 15 times - this is the MAC address of the host computer. Besides this the packet is made up of source and dest (FF FF FF FF in this case) IP addresses, checksums, a source MAC address, a dest MAC (FF FF FF FF FF FF) and various port and mode settings.
At some point I hope to get around to building this and testing it out - but for now, uni is pretty busy - I should also probably build the computer this will interface with first as well.

Problems (a)float

2006-09-06T17:10:00.000+10:00

My recent glossy posts have really gotten off topic - the topic of engineering project work. I will take off my marketing hat for a moment and put the engineering one (in this case software) back on.
An interesting recent problem I have been encountering is in the calculation of bearings. Well, not really the calculation of bearings - that part was rather trivial. It is a rather quirky compiler or emulator bug in how floating point numbers are used. Basically I can make assignments to these numbers without a worry (i.e. ratio = opposite/(float) adjacent). (You may recognise that I'm calculating bearings based on tangents - so next time a high school maths teacher gets asked why are studying trigonometry? they can answer - well when you are developing vectoring algorithms for autonomous craft it will really come in handy - NOTE: I wasn't the one to ask such questions - I'd just hear them again and again from the same people).
Back to the problem - when I try any compare these floating point numbers I come into grief.
Simple statements like:
if (ratio > 0)
or even:
if (ratio > 0.0)
would corrupt other data variables not even passed to the specific function.
To cut a long story short - I switched over to integers (which don't have any decimal places) which allows me to do the calculations in half the space and with much greater speed (I'm not sure why I didn't do this to begin with).

Souvenirs and sustainance

2006-09-04T16:37:00.001+10:00

Wades recent post on the open day and some questions from readers jogged my memory on a few open day points.
- The food was great - officially catered lunch and then some really well catered afternoon tea.
- A neat La Trobe hat - which made me less conspicuous when getting the afternoon tea.
- A handful of La Trobe sweets (which we managed to get from the CS department). Unfortunately I couldn't find where to get a CS hat (same as the engineering one but red), but the lollies made up for it

(The hat reads - "Engineer your future at LA TROBE UNIVERSITY")

Open Day

2006-08-31T17:46:00.000+10:00

As the creators of one of the more exciting exhibits from the engineering department, Wade and I were on hand at the La Trobe open day. We had an exceptionally flashy poster, which was designed by Wade. Along with this we had the UAV and a rolling display of video and still pictures displayed up on a LCD screen.
The whole experience was fun, but fairly exhausting (probably not for Wade - as he sat and coded the whole time). It was interesting to talk to various prospective students (and parents) who were in the same position as me 5 or 6 years ago.
One little goof up from the CS department was announcing our project as the Unnamed Aerial Vehicle - rather than Unmanned - grr.
Interestingly enough some people saw our Age and Herald Sun articles but I was just bad at picking them. Whenever I asked people had they seen them I got a really quizzical look, but others made a B-line for our display stating they had seen us in the paper

Herald Sun

2006-08-25T12:05:00.000+10:00

And for our next bit of fame we also made the Herald Sun newspaper - the paper with Victorias largest distribution.

Famous again

2006-08-18T11:14:00.000+10:00

It seems everyone is excited about our project. We have made page 2 of the La Trobe Bulletin.
Just watch the cover of Time Magazine :)

New Business card!

2006-08-16T19:03:00.000+10:00

Since I havn't made any major changes to my business card over the last 2 years or so - I decided it was time for something fresh and new. What better to use as a background but some pictures from my UAV - that's sure to be a talking point. It does look better printed (and of course includes the relevant phone numbers.

PCB Redundancy

2006-08-16T17:55:00.000+10:00

Ok, just last Friday our PCB was sent off to fabrication. This was the result of many hours of work - particularly to get the multitudes of miniaturised components to all fit in together (see the layout pic).
In a meeting with our supervisor we were given the advice - I'd have two, or maybe even three boards made up. The explanation was board 1 will be the original board. Board 2 will be the replacement when we destroy the original (remember this is an aircraft flying 100" up). Board 3 wouldn't get made up and we could use it as a reference to see where all the tracks go. Since we had only ordered one board initially - another is now on order with one week latency :)

Digital v's Analog

2006-08-12T10:51:00.000+10:00

Personally I have always been more of a digital fan - especially when it comes to university subjects. The maths is certainly much easier and I seem to have a bit of a knack of Boolean algebra. In engineering projects I like to do as much in digital as possible - this seems generally the easiest to design and maintain over time.
Having said this I recently purchased a digital tuner card for the PC. The card I purchased, based on Matt's recommendation was the Leadtek WinFast DTV2000. Since this card can record both analog and digital signals I thought that this would serve as an excellent comparison. Realistically TV has never looked so good in our house - the only problem appears to be an occasional pixilation (possibly caused by mediocre reception) and some jumping on HD Digital stations (which I haven’t worked out the cause of yet). Hopefully these things will sort themselves out shortly.

MY old friend - the 555 Timer

2006-08-09T14:45:00.000+10:00

After discovering a fatal flaw in my manual override design I turned back to one of my favourite IC's for the solution. The problem was the in the event of the receiver loosing contact with the transmitter the override circuitry would stay in it's previous state (autopilot or manual mode). If it was stuck in manual mode the plane would fly off into the distance and we would have know way of recover (short of running after it).

So back to the 555 - this is an extremely versatile and accurate timing IC. It basically requires only a couple of caps and a resistor to set the timing requirements - and hey presto - we have a timeout function which will activate emergency procedures if the timeout period has been exhausted. A transistor is used to discharge the cap, as retriggering can only occur when the 555 has finished it's timing cycle - so this is artificial retriggering.
And finally my quote to Wade - "now our project must be complete - it has a 555". For some reason almost any electronic design we work on - a 555 makes it in somehow.