Research On Self-propelled Linear Piezoelectric Actuator And Its Application In Motion Stage

Linear piezoelectric actuator has many advantages, such as fast response, high resolution small size, etc. It can achieve linear motion without conversion mechanism, so it was widely concerned in the field of precision driven. The existing planar three DOF motion platform has complex structure and high processing technology requirements. The design scheme of a kind of planar three DOF motion platform based on linear piezoelectric actuator is proposed to simplify the structure of the system and reduce the requirements for the surface quality of the foundation platform. The driving unit of the motion platform is constructed by using the piezoelectric stacks. The main contents of this paper are as follows:Aiming at such problems as complex structure, high cost, cannot balancing stoke and positioning accuracy in the existing linear actuator, a new type Self-propelled piezoelectric actuators with novel structures and principles was presented. It works in the nonresonant state and contains three drive units including three piezoelectric stacks, and can achieve bidirectional movements by applying with signal to each unit with a defined sequence.The structure design and working principle of the novel piezoelectric actuator were introduced in detail. The motion of the actuator in a signal cycle was analyzed. Based on the static model, the displacement response of the driving foot was derived. The relationship between the output displacement of the driving foot and the input displacement of the driving unit was also obtained. The dynamic model of the system in the movement direction was established, and pointed out that the actuator had two kinds of movement modes of stepping and sliding. The influence of signal excitation mode on the performance of the system is analyzed, and shows that the performance of the drive can be improved by using signal excitation mode of the harmonic function coupling linear function.The experimental test system is established, and the step distance, speed and load characteristics of the actuator are tested respectively. Experimental results show that the performance of the actuator is excellent, can achieve the movement with large stroke, high precision, high speed. The resolution can reach 7 nm, the maximum load of the actuator is 25 N, and the moving speed can reach 1.5 mm/s.A planar three DOF motion platform is constructed based on the design actuator. The motion mode and positioning performance of the platform are analyzed, and the method of realizing the platform location is given. A series of experiments are carried out to test the performance of the platform. The experimental results show that the platform can achieve the movement of the planar three degree of freedom. However, there are problems such as the interference of the movement, the instability and so on. The main task of the next step is to set up the displacement feedback control and select the appropriate contact interface.