Thebasic Research Of Electromagnetic-piezoelectric Hybrid Drive Multi-dof Motor

Multi-degree-of-freedom motors have gradually become a research hotspot,due to the continuous development of modern intelligent industries and the increasing requirements for the precision,integration and flexibility of multi-degree-of-freedom motion actuators in industrial applications.The driving modes of multi-degree-of-freedom motors are mainly divided into electromagnetic driving and piezoelectric driving.The electromagnetic driving multi-degree-of-freedom motor has high mechanical integration and simple transmission.It is suitable for working in high-speed and low-torque occasions,but its complex structure is difficult to achieve miniaturization,control and positioning accuracy is low,and it is not suitable for precision work occasions.The high-power electromagnetically driven multi-degree-of-freedom motor is large and has a problem of response delay.The piezoelectric driving multi-degree-of-freedom motor has the characteristics of compact structure,flexible design,easy miniaturization,self-locking,fast response,and immunity from external electromagnetic interference.It is suitable for working at low speed and high torque.However,the piezoelectric driving multi-degree-of-freedom motor has a short life and is not suitable for continuous applications.The shortcomings of these two driving modes of multi-degree-of-freedom motors limit their applications.Therefore,combining electromagnetic driving and piezoelectric driving methods to design an electromagnetic-piezoelectric hybrid drive multi-degree-of-freedom motor can increase the motor's rotational speed torque output range and response speed,and improve the problem of large size and response delay of high output power motors.Combining the advantages of an electromagnetically driven multi-degree-of-freedom motor and a piezoelectric-driven multi-degree-of-freedom motor,an electromagnetic piezoelectric hybrid-driven multi-degree-of-freedom motor was studied in this paper.The structure of a multi-degree-of-freedom motor driven by electromagnetic piezoelectric hybrid was proposed and its driving mechanism was analyzed.The influence of high-frequency vibration of the piezoelectric stator of the motor on the stator and rotor structure of the motor was studied,and the optimal size of the rotor structure was determined.The optimum frequency of the voltage excitation of the piezoelectric stator of the motor at high frequency was analyzed.Based on this,the dynamic response of the piezoelectric stator has been studied.The analysis results show that the design scheme ofthe piezoelectric stator is feasible.A finite element model of the magnetic field of the permanent magnet of the motor rotor was established,and the distribution of the magnetic field under different magnetization modes of the permanent magnet and the distribution of the air gap magnetic flux density at different positions of the permanent magnet were analyzed.An analytical model of the spherical harmonic magnetic field and an equivalent magnetic field of the motor rotor permanent magnet were established.The numerical analysis method has been used to compare the air gap magnetic flux density distribution of the two analytical models at different positions of the permanent magnet.The comparative analysis between the numerical analysis results of the magnetic field and the finite element calculation results was completed.The analysis results show that the magnetic field results obtained by the two analytical methods are correct and the calculation results of the equivalent magnetic field model are more accurate.It provides a basis for further establishing the electromagnetic piezoelectric hybrid driving torque model.Based on the analytical model of magnetic field,an electromagnetic driving torque model was established according to Lorentz's law of force.According to the first type of Fredholm equation,the force distribution and displacement of the contact surface of the stator and rotor were analyzed.A piezoelectric driving torque model was established based on Mindlin theory.Based on the structure of the motor,the electromagnetic driving torque model and the piezoelectric driving torque model,an electromagnetic piezoelectric hybrid driving torque model was established.The influence of stator friction material,stator mounting position angle and driving mode on motor torque was analyzed by numerical analysis.Finally,a prototype of the motor was developed,and the feasibility of the electromagnetic piezoelectric hybrid-driven multi-degree-of-freedom motor is verified through experiments,which provides a reference for the further optimization and design of the motor.