Cool Engineering

Info on some cool engineering projects

Monday, September 29, 2008

ROV braves the Moat

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.


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