Patent ID: 8897954

Claim:
A vehicle including: a chassis; at least one ground engaging mechanism configured to propel the chassis over the ground; a tool supported by the chassis to move material; at least one electric motor supported by the chassis and configured to convert electrical power into mechanical power, the motor having a rotor and a stator, the rotor having a magnetic field and the stator having a magnetic field; a sensor configured to provide an indication of the relative position of the rotor to the stator; and a controller controlling at least one of the magnetic field of the rotor and the magnetic field of the stator to cause an angular difference between the magnetic fields of the rotor and the stator, the controller controlling the angular difference based on a calibration test of the sensor wherein the controller calculates an error in the indicated relative position of the rotor in response to a torque applied to the rotor, wherein the controller is operative to operate the motor at a first speed and to increase the speed of the motor from the first speed to a second speed during the calibration test.