Gyro Rate Bias Issue

[Jared Russell]

We like to re-calibrate the gyro bias as close to the start of the match as possible. MEMS devices are highly sensitive to temperature and they self-heat as they draw current, so in the couple minutes between when you turn your robot on and when the match starts, your zero may have drifted a bit. It still isn't perfect, but it will be better than calibrating a cold gyro.

One automated way to do a reset that is commonly used in industry is a "zero velocity update" - if you know (via another source, such as wheel encoders or a button press) that your heading should not be changing, you can re-calibrate the bias on the fly and recover some of the accumulated heading error.

[Greg McKaskle]

The WPILib gyro code actually does compensate for this provided the robot is stationary when the Open is performed, and provided that the gyro temperature remains constant. It measure the baseline DC value during Open. The LV implementation averages over two seconds. This value is then used as the baseline DC voltage. The Reset operation doesn't measure the baseline again, it simply zeroes the accumulator.

Greg McKaskle