| One of the key technologies in nanotechnology,micro-manipulation relies heavily on highprecision positioning platforms.However,traditional high-precision positioning platforms are no longer able to meet the requirements of micro-manipulation.Therefore,it is crucial to design and research a high-precision and high-degree-of-freedom positioning platform with nanometer-level positioning accuracy or repeatability,compact structure,and fast response speed.In this paper,a parallel 6-DOF positioning platform based on a piezoelectric ceramic actuator is designed.The platform achieves nanometer-level repeatability and resolution.The paper includes the design and optimization of the platform’s configuration and guiding mechanism,the development of the platform’s pose control model,the proposal of a control scheme for the platform,and the experimental testing and simulation analysis of the platform’s performance.Based on the technical requirements of the parallel 6-DOF nanoscale piezoelectric platform,a preliminary design scheme for the platform structure is proposed.The guiding and preloading mechanisms of the piezoelectric ceramic actuator are optimized using flexible hinges.Different types and materials of flexible hinges are compared and analyzed.The relationship between the rotational stiffness of the flexible hinge and its structural parameters is calculated to determine the optimal parameters.Finite element simulations are conducted to verify the design of the flexible guiding and preloading mechanisms,thus finalizing the configuration design.The positioning principles of the six degrees of freedom of the platform are analyzed,and the pose control model of the platform is derived based on these principles.The displacement-to-voltage characteristics of the piezoelectric ceramic actuator are obtained,and MATLAB software is used to calculate the driving voltage required for the moving platform to reach the target pose.ANSYS software is employed for simulation analysis,and the simulation results are analyzed to validate the correctness and effectiveness of the pose control model.The hysteresis nonlinearity,creep characteristics,and other properties of the stacked piezoelectric ceramic actuator are analyzed for their effects on the actuator’s output.A PI hysteresis model is established to compensate for the hysteresis nonlinearity,and the inverse model is used as the basis for feedforward control of the piezoelectric ceramic actuator.Based on the structural design and technical requirements of the parallel 6-DOF nanoscale piezoelectric platform,a feedback device for closed-loop feedback control is selected,and a closed-loop feedback control based on a PID controller is established.Finally,combining feedforward and closed-loop feedback control,a control scheme for the eight piezoelectric ceramic actuators of the platform is proposed,and the system block diagram of the control system is provided.Experimental testing is conducted on the constructed test platform to examine its static performance.The results demonstrate that the platform exhibits nanometer-level repeatability,resolution,and absolute positioning accuracy.The dynamic performance of the platform is verified through ANSYS software simulations.The natural frequencies of the flexible guiding and preloading mechanism and the first six modes of the overall platform are analyzed,indicating good stability.The coupling and crosstalk between the six degrees of freedom of the platform are analyzed,showing excellent decoupling performance.Overall,the proposed parallel 6-DOF nanoscale piezoelectric platform with high precision and high freedom degree meets the requirements of micro-manipulation.Its design and control scheme are validated through experimental testing and simulation analysis. |
PDF Full Text Request