Research On Stepping Type Piezoelectric Actuators Based On Compliant Foot Driving

Precision driving technology with micro/nano scale is the key technology in many fields.The actuators which can output precision linear or rotary displacements are the core driving device for the precision driving technology and the performance of these actuators has direct influence on precision driving technology.The traditional actuation devices cannot fulfil the high-precision requirements in many fields.As the novel actuation devices,the stepping type piezoelectric actuators overcome the defect of small deformations of the piezoelectric materials and possess the notable advantages of high output accuracy,wide velocity band,long working range and quick response speed and they are widely used in precision driving field.After adequate investigation and analysis,with the main clue of “amplification of the working stroke”,the dissertation induces and classifies the existing piezoelectric actuators,introduces the structural configurations and worki ng principles,analyzes the derivative relationships and performance differences,and summarizes the advantages and disadvantages for the existing piezoelectric actuators.We find the existing inertial piezoelectric actuators are suffering from the low load capacity and the existing seal piezoelectric actuators have the dissymmetry between the forward and backward motions.In order to solve the problems,the dissertation proposes two kinds of compliant foot driving schemes: Driving scheme with single input and independent foot which is applicable to the inertial piezoelectric actuators and driving scheme with double inputs and coupled feet which is applicable to the seal piezoelectric actuators.Base on the driving scheme with single input and independent foot,we develop the linear and rotary actuators with single input and independent foot.Base on the driving scheme with double inputs and coupled feet,we develop the linear and rotary actuators with double inputs and coupled feet.The dissertation introduces the configurations and working principles of the actuators,builds the electromechanical model of the piezoelectric ceramics,and deduces the flexibility matrices of the leaf-spring flexure hinge and right-circular flexure hinge.We build the motion model of the linear piezoelectric actuator with single input and independent foot and deduce the theoretical relationship between the input and the output for the driving foot.The finite element analysis software is utilized to simulate the deformation and optimize the parameters for the driving foot.The working performances of the prototype,such as the relationship between the output and the driving voltage,the motion resolution,the relationship between the output and the driving frequency,the relationships between the motion velocity and the driving voltage and frequency,the load capacity,the return error,and the parasitic displacement,are also studied by the established experimental system.The single hinge pseudo-rigid-body model of the driving foot is biult and with the pseudo-rigid-body model,the motion model is also built for the rotary piezoelectric actuator with single input and independent foot.The effect of pre-tightening state of driving foot on the performance of actuator is analyzed.The displacement of the driving foot is simulated and the modal analysis is conducted.The working performances of the prototype,such as the relationship between the output and the driving voltage,the motion resolution,the relationship between the output and the driving frequency,the relationships between the motion velocity and the driving voltage and frequency,the load capacity,and the return error,are also investigated.The motion model is established for the linear piezoelectric actuators with double inputs and coupled feet.The working principle of the driving mechanism is analyzed in theory and the motion trajectories of the binate driving f eet are also deduced.The deformation,motion and stress distribution of the driving mechanism are simulated and the modal analysis for the stator is conduct.The working performances of the prototype,such as the relationship between the output and the driving voltage,the motion resolution,the relationship between the output and the driving frequency,the relationships between the motion velocity and the driving voltage and frequency,the load capacity,the output force,and the parasitic displacement,are also researched.The motion model is established for the rotary piezoelectric actuators with double inputs and coupled feet.The motion process of the driving mechanism is analyzed.The motion trajectories of the binate driving feet,the stress distribution of the driving mechanism and the mode shapes of the stator are simulated.The working performances of the prototype,such as the output displacement,the motion resolution,the relationships between the motion velocity and the driving voltage and frequency,and the output torque,are also studied by the experimental system.On the basis of the proposed actuators with single degree of freedom,we develop the linear-rotary piezoelectric actuator based on surface foot driving.The configurations and working principles are introduced and the experimental performances are also studied.The dissertation accomplishes the systematical research work,such as the structural design,modeling analysis,simulation optimization and experimental demonstration.The feasibility of the driving principles is proved and the good performances and application prospects of the proposed actuators are also verified.