Research On The Speed Control Performance Of Ultrasonic Motor

USM is a new kind of motor developed in the 1980 s. It works under the friction between the rotor and stator which vibrates within the ultrasonic frequency band due to the inverse piezoelectric effort. Compared with the traditional electromagnetic motor, USM have advantage in power self-locking, greater torque in low speed and responses more quickly. At present, USM has been applied in high technology field such as aerospace and robots.USM responses to its driving signal so quickly that it may produce shock due to the oversized or even discontinuous acceleration without appropriate control plans during the speed switching. Such effect becomes inevitable if the USM needs to switch between high and low speed frequently. This paper designed and realized three kind of speed curve in terms of jerk control.The main content of this paper are as follows:First, the characteristics, history of development and current research situation of USM are introduced as well as the concept of jerk and the necessity of jerk control for the speed switching of USM.Second, the system scheme is designed. The T-measuring method is used to cover the details of speed fluctuation in low speed. The DDS technique is employed for a fine tuning resolution of the driving signals. Under the principle of the acceleration had to be continuous, three kinds of speed curve are proposed and the classic PID control method are decided to be used for speed tracking for the indirect control of jerk.Third, the software and hardware of the system are designed. The hardware contains speed measurement module, USM driving controller and communication module.The software comprises of host computer software based on Labview and slave computer software based on PSoC. The host computer accepts data, sends instructions and draws curves of the motor characteristics. The slave computer runs the speed measurement program and control program, and sends data.At last, three methods of jerk control are carried out under different conditions and the results of the experiments are analyzed.