| With the development of nanotechnology,there is a great demand for high precision drive and positioning technology.With the advantages of high driving precision,fast response speed,simple structure,etc.,the piezoelectric actuator has been widely used in the field of high precision driving and positioning.However,the deformation of the piezoelectric material is small(10-100μm),so the driving stroke of the piezoelectric actuator is also short.Therefore,the piezoelectric actuator cannot meet the requirement of long stroke(millimeter).In addition,piezoelectric actuators behave hysteresis in applications,which cause a significant nonlinearity between the excitation and response of the system.This will affect the accuracy and stability of the drive,and will increase the design difficulty of the control system.In order to improve the stroke of the actuator,we design a piezoelectric inertia-friction actuator(PIFA),which combines the high-precision performance of the piezoelectric actuator and the long-stroke characteristics of the inertia-friction drive principle.In this paper,the physical object of the piezoelectric inertia-friction actuator is designed and built,then the dynamic model of the second-order system in the actuator system is established.In order to solve the influence of the hysteresis nonlinearity of the piezoelectric actuator on the PIFA system,we develop a novel charge control circuit for control of the piezoelectric actuator to overcome its hysteresis nonlinearity when the actuator is driven at high voltage(as opposed to low voltage reported in literature).The charge control circuit also includes a balancing resistor.A test-bed for a piezoelectric actuator is established and an experiment is conducted.The result shows that the hysteresis nonlinearity of the piezoelectric actuator was reduced by 82%under the proposed charge control circuit.For the motion control of PIFA,we design a composite controller to achieve high precision and faster drive speed.The movement process is divided into step mode and fine mode.A step mode controller which adopts the voltage proportional control method to achieve faster moving speed and a fine mode controller which adopts a feedforward controller to achieve higher driving precision is designed.The experimental results show that compared with the traditional voltage proportional control method,the step and fine mode controller can significantly improve the accuracy and driving speed of the actuator system.The contribution of this paper includes the novel charge control circuit for high voltage application and the novel controller for PIFA. |
