KOP Gyro seems to run-on after turn stops

[PhilBot]

Hi

I'm trying to implement a closed loop controller with the KOP Gyro, and it seems to have a major flaw !!!

The initial symptoms were that if you locked the current heading when the operator stoped turning the bot (joystic returns to detent), the controller would steer the robot BACK about 30 degrees.

I initially suspected my code, but finally I had to start looking at the actual Gyro input. By just wiring the Gyro to a stand-alone RC unit on analog channel 1, I could display the gyro angle whenever it changed.

If I spin the gyro, the heading starts changing immediatly, but when I stop it, the heading changes continue on for almost another SECOND. Once again I suspected my software (maybe overflowing the serial port), so I changed the input to a pot so I could simulate gyro input.

With the POT, the heading stopped as soon as I returned the put to neutral.

So, it really looks like the Gyro output doesn't go to zero (bias) quickly when the turning stops. I even tried widenning the deadband, but that didn't help either. Can anyone verify/disprove this from recent experience?

So, it seems to me that with such a long run-on, the gyro is next to useless for any sort of high speed control. The best I can expect is a drunken meander across the field.

Any suggestions would be greatly appreciated.
Phil.