VICTOR RESPONSE DELAY? - AGAIN

[yoyodyne]

Thanks Al,

I guess I will transition an I/O pin as a timing reference and then monitor the PWM output and VICTOR outputs on other channels to make a measurement. Using PWM 15/16 will remove whatever delay the master processor adds. Other people must have done this as well. When we look at the data I posted we see a period of 250ms where the angular rate remains unchanged after the PWM output is changed and then after the angular rate actually begins to change it takes an additional 175ms or so for the robot to actually stop. But of course when the robot stops the wheels and drive train are spinning furiously in reverse. I figured that even though it would take time for the system to react (including armature speed, gear, chain, and finally the robot chassis momentum) that you would start to see at least the effect of removing the drive voltage right away. But maybe that is not the right way to look at it.

I'm assuming that a four wheel drive robot on carpet will stop faster than the two wheel drive robot on a waxed floor and that will reduce the 175ms part but not have much effect on the 250ms component. If the 250ms component of the stopping time is mostly a characteristic of the motors, gear box, and chain linkage then it should be similar for the real robot and we can use the angular rate to predict when to slam on the breaks. Since it looks like the loop bandwidth needs to be pretty low to accommodate the system lag maybe a binary control approach makes the most sense.

Greg