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Spockie-Tech
Site Admin
Joined: 31 May 2004
Posts: 3160
Location: Melbourne, Australia
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Woot, someone *has* been having fun..
Microprocessor happy as I am, that sounds like a damn impressive piece of work.. I hope it all hangs together under the stress of combat though..
Rick (Moth) has found that theres a lot of difference between making something tick on the bench, and keeping it ticking after a solid pounding in battle while surrounded by electromagnetic storms, power surges and vibration and shock. Thats why a lot of the American builders gave up on the complex IFI systems and went back to standard proven reliable RC gear, even after they released a version II "Battle Hardened" revision..
Dont get me wrong, I think its great that someone is developing systems like this, but if you are going to sell it to builders who have a few more thumbs and few less bit-blitter skills than you do, before its had some serious fight-time, be prepared to spend quite a while debugging other people's bots..
P.S. If you find any better options than the HIP chip for H-Bridge Mosfet control, please let us know.. I'm turning over some ideas for the IBC Mk II in my head at the moment, and would like to get away from the HIPs in future (if possible, I havent heard of a better option yet).
It would be nice to find a driver chip that survives the destruction of the Mosfets more than the HIP does. They're expensive little things and when a mosfet goes, it often takes them out as well.
Congratualations on your development work so far.. _________________ Great minds discuss ideas. Average minds discuss events. Small minds discuss people
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Wed Feb 08, 2006 11:57 pm |
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DumHed
Experienced Roboteer
Joined: 29 Jun 2004
Posts: 1219
Location: Sydney
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that looks pretty good
I generally do surface mount stuff, but for this robot stuff I'm doing as much of it through hole as possible for extra strength and ease of servicing - but the modular design allows swapping whole modules rather than trying to fix things between battles.
This morning I built up a receiver board, and then the frustration began!
It wasn't responding to the transmitter at all, and when I put the scope on the signal coming in from the RF module it looked strange. The channel pulses were fine, but it was missing the sync pulse, and the gap in between didn't have sharp edges. The signal was sort of floating.
After prodding all kinds of things and pulling the transmitter apart to verify that it was sending the right stuff I adjusted the fine tuning on the RF module.
That got the sync pulse back, but the whole signal was inverted!!
After more tweaking I managed to get the signal showing up properly, but every now and then it'd turn to static.
So, out with the high quality expensive RF modules, and in with the cheapo Jaycar ones that don't have a tuning adjustment
Once it was working nicely I tried out the hardware failsafe, which actually works really well, but I'm using the wrong transistor for the job so I need to get the right one (2N7000 MOSFET).
At the moment it works, but while at full output the failsafe sags and the PWM signal into the opto board can be lost.
A bit of playing with component values should be all that's needed.
I loaded in the software for the
DDR
version of the receiver, plugged a servo in, and it works!
I get PWM / direction signals, and a steering servo drive out of the one 17x29mm board!
I haven't built up the FET and relay driver board yet, but I've tested things out using my other FET board, which does seem to work ok.
Edit: the hardware failsafe works with the new FET in it
I can change component values for different timeouts, but at the moment it kills the outputs in about a quarter of a second after the transmitter is turned off. _________________
The Engine Whisperer
- fixer of things
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Thu Feb 09, 2006 11:48 am |
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