Research On New Linear Ultrasonic Motors And Their Application In Motion Stage

Linear ultrasonic motors have been developing rapidly in recent years and they are playing animportant role in microminiaturizing precision driving systems for their attractive characteristics ofsimple mechanical construction, easy to realize miniaturization and lightweight of the device, highpositioning accuracy, direct drive, no electromagnetic interference and so on. Now, several types oflinear ultrasonic motors have been commercialized by some foreign companies and well used in somehigh technology fields. However, the study on the linear ultrasonic motor is immature and there is noproduct for sale in China. At the same time, the high-end products of linear ultrasonic motors arelimited to export to China. Therefore, there is much need to strengthen the efforts to study linearultrasonic motors.Supported by NSFC (No.50735002) and NSFC-Guangdong Natural Science Foundation(No.U0934004), this dissertation presents a systemic research on drive mechanism, optimizationdesign and experiment, contact dynamic model, performance simulation. Furthermore, three newtypes of linear ultrasonic motor have been used in moving stage and achieved long stroke and highprecision. To conclude, main contributions of this dissertation are as follows.1. The characteristics of linear ultrasonic motor are systematically summarized and theclassification method of them is proposed. At the same time, the state of the art of linear ultrasonicmotors and their applications both here and abroad are reviewed and summarized. Furthermore, theapplication prospects of linear ultrasonic motor are described and the need for the study of linearultrasonic motors is proposed.2. The key problems in design of linear ultrasonic motors are summarized and analyzed: theperformance figure of piezoelectric ceramic and its strain induced mechanism, the formation methodof elliptical motion, the requirement for piezoelectric ceramics, materials of the stator and the slider,friction materials, and so on.3. A new design theory of the wheel-shaped linear ultrasonic motor based on bending modes isproposed. The motion mechanism of the motor is analyzed in detail. The dynamic design of the statorand the optimal design of the whole structure of the motor are carried out. Three types of linearultrasonic motors with wheel-shaped stator have been fabricated.4．A new linear ultrasonic motor with triangular structure based on in-plane modes is proposed.The operation principle, dynamic performance and structural optimum design of the stator areanalyzed and described in detail. The especial design of the stator is its isosceles triangular structure part, which makes the motor structure compact and easy to realize miniaturization.5. A butterfly-shaped linear ultrasonic motor is used as an example to study on the new optimumdesign method of linear ultrasonic motors based on response surface methodology. Many designrequirements of optimal results can be well fulfilled: the work mode frequency difference is little(<100Hz), the amplitude of the driving foots is large (>2μm), the disturb modes are far away fromworking modes (>1kHz) and the amplitude of the clamping points is little (<1μm).6. A contact model is established based on coulomb law of friction, which simultaneouslydescribes the dynamic behavior between the slider and the stator. The influence of the modelparameters on the motor behavior is studied to find out the requirements for an optimal contactbetween the slider and the stator. The model prediction agrees well with the experiment data.7．Several types of positioning stage drived by different linear ultrasonic motors developed inthis dissertation have been fabricated. At the same time, the measurement and control systems havebeen constructed. The motion stages realize long stroke(~100mm) and high positioning precision (±0.5μm).