Sports Biomechanics Lab > Blog > Steer Angle: Pots or Gyros?
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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:
  1. Differentiated (and filtered) the steer angle from the pot and compared it with the steer rate from the rate gyro signals.
  2. Integrated the steer rate from the rate gyro signals and compared it with the steer angle from the potentiometer
My conclusions:
  • 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.
Angle Estimation
Estimation of the steer angle from the steer rate.
Angle Estimation Zoomed
Zoomed view of the angle estimation from the rate gyros.
Rate Estimation
Steer rate estimation from the steer angle potentiometers.
Rate Estimation Zoomed
Zoomed view of the steer rate estimation.

 

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