Research On Key Technologies Of Miniature Disc Traveling Wave Ultrasonic Motor With Compound Excitation

Comparing with traditional electromagnetic motor,traveling wave rotaryultrasonic motor has the advantages of simple structure,low speed,high torque,flexible,power failure self-locking,no electromagnetic interference and so on.Ithas wide application prospect in the fields of space attitude adjustmentmechanism,precision positioning,robot joint,and precision instrument in nomagnetic environment.At present,the ring axial bending vibration modalityadopted in most of traveling wave rotary ultrasonic motor is used to the excitation,on which the excitation way mainly depends on driving feet. Circular motion isproportional to the thickness of stator,which affects operating speed,responseprecision and output torque of actuator.As bigger as the thickness of stator,andsmaller of the amplitude of bending vibration,the overall size of motor will bebigger.The applications above-mentioned are not ideal. Compound excitation ismore suitable for the above application, because it can better resolve theproblems on the stability of amplitude and the miniaturization ofactuator.Currently,the research and application on ultrasonic motor withcompound excitation are exploratory research at home and abroad.There aremany key problems on science and technology needed being discussed moredeeply,such as the theory,structural design,friction principle,control algorithm,miniaturization and so on.The study in the thesis is based on the above problemswhich will provide new thinking and theoretical principles for the research onminiaturization of traveling wave rotary ultrasonic motor and which will be ofrealistic significance to be covered.Herein,the effect of compound coupling relationship between longitudinalvibration and bending vibration on driving performance based on the motionprinciple of traveling wave ultrasonic motor is researched.The overall optimizat- ion of miniature disc ultrasonic motor with longitudinal bending mode isdesigned by the use of finite element modeling analytic methods.Friction materialand conversion principle suitable for the motor are provided,the controller isdesigned by using optimization algorithm,test and experiment device are basedon the prototype, and the key problems are discussed.The main research contentsare as follows:1.The structure of patch disc compound excitation traveling wave ultrasonicmotor with longitudinal bending modality conversion is proposed based on themodality conversion principle.The structural parameters of ultrasonic motor aredesigned by the use of finite element analysis method,the finite element model ofmotor is established,and characteristic frequencies of two vibration modes of themotor are degenerated.The spectrum of vibration trajectory of driving gear isestablished and the electrical characteristics are analyzed.2.Prototype of miniature compound excitation disc ultrasonic motor with24teeth is designed and made, of which the diameter of the prototype is30mm.Theprototype proposed in the thesis resolves the problem of continuous contactbetween stator and rotator by the use of gear structure.The vibrationcharacteristics and impedance characteristics are tested,by which the experiment-tal study is completed.The validity of the theory analysis is tested, and the studyon finite element is verified.3.The method of friction materials and the conversion principle of nanomaterial is discussed,by researching on the characteristics of micro morphologyof materials,load response, friction coefficient and so on.The problem of theengagement between microscale deformation of friction materials and micronmotion of ultrasonic motor is resolved in order to increase the output torque.4.An adaptive particle swarm optimization algorithm with random inertiaweight (APSO-RIW) is proposed, which is adopted to the controller of theprototype to optimize the PID control parameter. Comparing with otheralgorithms this optimization algorithm has advantages of improving theconvergence speed and precision positioning of controller. Actuator of ultrasonicprototype is designed based on DSP and DDS.Frequency range of the actuator isbroadened, and the precision of phase conversion error is improved.5.A test device for ultrasonic motor based on LabVIEW is designed. Compa- ring with the measuring method based on traditional discrete instrument,theresults show that the data derived from the two methods are basically the same.