Research On The Stepping Peristaltic Rotary Precise Piezoelectric Actuator And Its Control System

In the field of modern precision operation,micro-nano operation has become the key technology;there are strong demands for actuators with high resolutions.Piezoelectric actuators usually convert electrical energies into mechanical energies by using the inverse piezoelectric eff ects and frictional forces.They have simple structures,fast responses,low speeds,self-locking when power off and high positioning accuracies,which give them wide application prospects in robot joints,optical instruments,MEMS,positioning stages and space mechanisms.At present,most of the existing precision piezoelectric actuators are linear type;there are very few precision rotary piezoelectric actuators,which limit the application of the non-resonant piezoelectric actuators.Furthermore,they also have problems of low resolutions or limited strokes.Therefore,there is a lot to do to develop the rotary precision actuators.In this work,a new walking type rotary precision piezoelectric actuator with a mechanism combined driving and clamping is proposed.Firstly,the operating principle and the mechanism of the proposed actuator are discussed in detail.And its structure is designed,the ANSYS finite element simulation model of the vibrator is established and the static analyses are accomplished to get reasonable structural parameters.Secondly,a transducer dynamic analytical model and contact model between the rotor and driving foot are established,the relationship between the transient response of the driving foot and the driving signal parameters is obtained through the theoretical model,conditions for stable motion of the actuator and the relations between driving force and the preloading are established.Next,the relationship between output displacement of piezoelectric actuator and the driving voltage is established by combining the two models based on operating principle and the mechanism of the actuator.Finally,according to the above analysis of operating principle and the establishment of theoretical model,the driving control system of piezoelectric actuator is designed based on MATLAB Simulink Real-Time Workshop.A prototype was manufactured to verify the feasibility of the proposed actuator.The driving characteristics of the piezoelectric actuator prototype was tested : the relationship between the output displacement and the excitation voltage amplitude,frequency is obtained,so as the relationship between the output speed and load torque.A minimum resolution of 0.095 ?rad and a maximum torque of 49 N·mm were achieved by the prototype,and the output speed was varied by changing the driving voltage and working frequency.PID control method is used to implement the closed-loop control of the piezoelectric actuator displacement,which has realized a very precise and stable displacement control with a steadystate error less than 0.448?rad(0.092?)under a step signal and less than 6% of signal amplitude under a sine signal.