Modeling and Control Of Surface Acoustic Wave Motors

This thesis introduces Rayleigh waves and describes the generation of Rayleigh waves. Furthermore, the principle of operation of a SAW motor is analyzed. The analysis is based on a contact model, which describes the behavior between slider and stator. Due to the contact model, the microscopic and the macroscopic behavior can be studied simul- taneously. This model explains typical SAW motor features and determines the influence of parameters. The influence of the model parameters on the SAW motor behavior is studied in order to find the requirements for an optimal contact between slider and sta- tor. The models are validated. To control the SAW motor a linear time invariant system model of the SAW motor is derived and the disturbance sources of the SAW motor are determined and discussed. For closed-loop control, it is useful to eliminate the exist- ing varying dead-band between input and slider velocity. To this end, different actuation methods are investigated. Furthermore, controllers are designed, implemented and tested. Finally, the motor design is studied to obtain an indication for the applied materials, the geometry, the construction, the actuation and the practical limitations. Moreover, a design trajectory, to find initial design parameters, is proposed.