Chalmers currently has built five vehicles, four bikes and one e-scooter. All the bikes contain the same electrical and electronic parts, with the exception of the drive motors which are different for different bikes. The e-scooter has also the same electrical and electronic parts except for both steering and drive motors. The onboard computer is a myRIO-1900 which implements a LabVIEW programand all vehicles include the following sensors and actuators :

• Sensors

  • Hall sensor : measures the forward speed of the bike

  • IMU : measures the acceleration and angular speed of the bike

  • Steering encoder : measures the angle of the steering bar

  • GPS : measures the position of the bike

• Actuators

  • Steering motor : steers the front wheel to balance the bike and change its direction

  • Drive motor : spins the back wheel (red bike) or front wheel (black bike) to give the bike a forward velocity

Mälardalen Högskola (MDH) has built one bike. It contains similar sensors and actuators to the Chalmers bikes. The main computer is also a myRIO-1900.

Testing procedure for the Chalmers bikes

1. 1. Define a trajectory in any of the following ways 

      1. • Walk bike and record the path. Velocity is defined independent of walking speed.

         • Indicate GPS coordinates, latitude and longitude of points, that are on the desired trajectory. 

   2. Check that the chosen trajectory is feasible for the bike:

      1. • The bike is simulated with the proposed trajectory. 

         • Warnings are given if the bike exits its domain of validity. That domain is defined by accepted values of internal states as roll and steering angles and their derivatives but also if any actuator or sensor is outside its range of validity. 

   3. Perform test : the test follows this procedure :

      1. • The program on the bike is started from a computer or mobile phone connected by Wifi to the bike

         • The sensors are calibrated. The bike must not be moved during the calibration. A message is given when the calibration is finished.

         • For the first 2s,one needs to walk the to estimate the offset of the steering encoder.

         • After 2s up to 5s, one needs to steer the bike while the drive motor accelerates the bike to the reference speed defined in the trajectory.

         • At 5s, the steering motor is enabled and the bike, follows the trajectory, and this is the start of the test drive.

         • At the end of the trajectory, the bike can run in circles or turn around and drive back to the path’s start point. A user will have to manually end the test and catch the bike. 

   4. Evaluate test :

      1. • A validity test checks all recorded data to see if there were any exceptions which could invalidate the test. This could be strange sensor values, that the state of the bike went outside the normal domain of operation or inconsistencies in sampling times. The test is partly the same as the one for testing the feasibility of the trajectory.