Quote:
Originally posted by Ogre
I have a question about the speed of crab steering.
If 2 robots are about to hit head on, i.e. you are driving forward, and you move sideways (not turn but move the whole bot with the front still facing in the same direction), then backwards (with the front still facing in the same direction), how quickly does it turn? Is the reponse immediate, or does it take a second for the wheels to turn, and the robot kind of loops around? Does it also depend on the speed/torque of the turning motors?
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This very much depends on your steering motors and your programmers. For our robot last year (226) we were using the third drill motor in low for the steering motor. We used Dr Joes robust drill shaft to a small (about 14 tooth) sprocket using a trantorque. The steering modules had a 60 tooth gear on each. In this scenario the steering is instant (<1 sec) our only problem is that the modules were set up in software to only steer from straight right to straight left (180 degrees) so if you went from straight right (0 degrees) to say 300 degrees the wheels flipped over to 120 degrees and the motors reversed direction. This move took about a second and the robot did a little crazy weave for a few feet until it took off in the opposite direction. We also tired some other things such as mounting a 10 turn pot on the chain to sense position, however this led to less accuracy than sensing the actual of the steering module. If we were to do it again we would split the front and back and mount the feedback directly to the steering modules. Also I think we overbuilt them with full bearings and such, using more delrin and bushings would probably stand up just as well. Here is a pic from the inside of the chassis during the build phase
http://www.chiefdelphi.com/forums/pi...&quiet=verbose