Robot bicycle description

## Sensors
* Optical encoders measure steer angle, steer angle rate, wheel angles and rates
* Three axis angular rate gyroscope and three axis accelerometer fixed to
  rear frame measure body fixed angular velocity of rear frame and acceleration
  of a single point fixed to frame.

## Actuators
* Rear hub motor to control speed
* Steer motor to control balance and heading

## Feedback control:
* Sample and control loop running at 200 Hz
* Motor torque controlled via PWM
* PID speed control
* LQR/LQG yaw rate controller
* Sensor fusion, data logging, and control law implemented in C/C++ on an ARM
Cortex-M4 MCU running at 168 MHz
* Sensor data logging to microSD
* Real time telecommand via XBee 2.4GHz radio

## System identification experiments:
* Straight line running, vary v in [0.5, 7.0] m/s, input sinusoidal steer torque
  disturbance with frequency in [.1, 10] Hz.  Measure response, apply system
  identification techniques to identify transfer functions from steer torque to
  steer, steer rate, lean, and lean rate.

* Collect data over a family of steady turns, varying lean, steer, and speed. 
  Compare estimated applied steer torque to that predicted by Whipple model.