Patent classifications
G05B2219/41214
METHOD AND A MEDIUM FOR COGGING COMPENSATING A MOTOR DRIVING SIGNAL
Given a method for driving an electric motor in a direct drive environment, it is an objective of the present invention to smoothen the effect of cogging torque. The objective is solved by the method comprising calibration steps: a) control the motor to run at a first velocity in a first direction and, while miming the motor in the first direction, measure first current values for a plurality of motor positions, the first current values indicating currents required to run the motor at the first velocity at each of the plurality of motor positions; b) control the motor to run at a second velocity in a second direction and, while running the motor in the second direction, measure second current values for the same plurality of motor positions as determined in step a), the second current values indicating currents required to run the motor at the second velocity at each of the plurality of motor positions; c) for each motor position of the plurality of motor positions, calculate an average of the first and the second current measurements to generate averaged current measurements values for the plurality of motor positions; and d) store a map between the plurality of motor positions and corresponding averaged current measurements values; the method further comprising motor driving steps: e) receive a desired driving current; f) receive a signal indicating a motor position at a present time; g) use the map to determine a delta current for the motor position at the present time; h) add the delta current to the desired driving current to generate a compensated driving current; and i) drive the motor using the compensated driving current.