|
I have to disagree with GregT
of course you cant turn your robot faster than the 75° per second limit of the gyro, and expect to get useful data out of it. Thats one reason we used a V turn instead of a 180° arc in auton mode, if you only need to turn 45° then a half second is not very long.
As for normal steering, you very seldom need to turn your bot faster than that, and if you do, have your closed loop steering selectable with an over-ride button. Having closed loop feedback steering makes the bot INCREDIBALLY more controllable - esp if you are trying to stack boxes, pick up a box...
and we also found it was very difficult to drive our bot up the ramp without closed loop steering - esp when we had two drive wheels and two castors - if you were half way up the ramp and one wheel started to slip a bit, by the time the driver corrected for it, the bot was going sideways
but when we close the loop with the gyro, the bot goes EXACTLY where you tell it to go, no matter WHAT!
as for integrating the signal in SW - 40 samples per second is not enough for you?! I dont understand your reasoning - any machine this heavy cannot change its rate of turn very quickly, certainly not 40 times a second - so the signal that is coming from the gyro is already 'averaged' by the inertia of the robots mass.
We did some playing around with the 'gyro compass' on our bot - we could set a limit so it would not turn past a certan angle in either direction - lets say 360°. You could start the bot out heading north, and spin it all the way around and when it hit 360° it would not turn any further - like it was hitting an invisable wall, then you could spin it all the way around the other way, and it would stop at 360 again - dead on - and you could do this for several minutes with no visable drift in the compass accuracy - it was really cool to play with.
If you were getting noise from the carpet in your signal while trying to use it for steering, then maybe you didnt have it mounted flat. If you mount the gyro angled, then it will respond to motion in two axis instead of the one you want.
I had also read that you need to add external filters and circuits and whatnot to make the gyro 'usable' - we didnt use any, and we had no problems at all. Our closed loop steering was very stable and useful, and our integrated 'compass' heading put our auton V turn dead on 45° every single time.
|