Lab 3 - Motor Construction and Control

Some of the motor parts weren't as perfect as we wanted, so we ended up damaging the motor parts while we were characterizing the motor properties. However the deligent GSI, Hasan, was there to supply us spare parts. We followed the iTouch motor assembly instruction provided to us. The majority of the time was spent on reducing the friction between the rotor and the housing. The friction was minimized by the generous use of spacers/washers and multiple reassembly trials. The total number of wire winding was 22.

We used the sign-magnitude method to control the motor speed. We were not able to control the motor torque as we had no way to control the current flowing in the system. Arduino conveniently provided the sign-magnitude method capability via its analogWrite function. The H-bridge assembly (Pololu motor controller) was used to control the motor. The PWM signal and the direction signal were sent from Arduino. The both signals were in digital inputs and their magnitudes (high or low) determined the speed and direction the motor would rotate.

The controllable variables were the direction and motor speed and the feedback available from the motor was the rotor's relative location determined by the hall effect sensor mounted in the middle of the pendulum. Using these resources, we were able to implement multiple control strategies (P, PI, and etc) to achieve our goals throughout the lab experience.