Patent ID: 9344012
Filing Date: 2016-05-17
CPC Classification: H02N

Claim Text:
1. A method for controlling an ultrasonic motor coupled to a motor driver circuit, comprising: obtaining a position of a first encoder coupled to the ultrasonic motor; obtaining a position of a second encoder; determining a dynamic target position based on the position of the second encoder; calculating an error between the position of the first encoder and the dynamic target position; and repeating the obtaining, determining and calculating until the calculated error is equal to zero; wherein when the calculated error is greater than a threshold error value, sending a first control signal to the motor driver circuit to control the ultrasonic motor as a bang-bang controller to adjust the position of the first encoder; and wherein when the calculated error is less than the threshold error value, sending a second control signal to the motor driver circuit to control the ultrasonic motor as a proportional integral derivative controller to adjust the position of the first encoder.