Steer Angle: Pots or Gyros?
by Jason Moore — last modified Jul 15, 2010 01:30 PM
I'm working on choosing sensors to measure the steer angle and rate of a bicycle.
This is data from the instrumented bike we had in Delft. I took the raw potentiometer voltage and converted it to steer angle and I took the "yaw", "roll" and "steer" bike mounted rate gyro voltages and converted them to steer rate We used Silcon Sensing CRS-03 100deg/s rate gyros and a pretty nice pot from Feteris (FCP40A). Then I did two things:
- Differentiated (and filtered) the steer angle from the pot and compared it with the steer rate from the rate gyro signals.
- Integrated the steer rate from the rate gyro signals and compared it with the steer angle from the potentiometer
- You can reasonably estimate the steer rate by differentiating the steer angle signal. There seems to be some time offset, not sure about that yet.
- The gyro's do not noticeably drift when looking strictly at the raw rate signal.
- You can integrate (trap rule) the steer rate from the gyros and get a good estimation of of steer angle. (Although my integrated signal seemed to have the wrong scale, like it was missing a multiplication factor, I'm not sure about that)
- The integrated signal shows little to no drift over a 60 sec time period
The CRS-03 sample price is $300 each. I may buy one.