Design And Control Of A 2-DOF Precision Positioning Stage With A Large Motion Stroke

Precision positioning platform as one of the key technologies of precision manufacturing,measurement,to manipulate micro-nano technology,semiconductor packaging,and other fields,has a very important application value and theoretical research value.As science and technology development and progress in all areas,higher requirements are put forward for precision positioning platform,and high precision positioning stage with a large motion stroke urgently needed.In this paper,a precision positioning stage with a large stroke and high accuracy is presented and the design of structure,parameters identification and control methods are studied.The main achievements are summarized as follows:In the section of structural design,a voice coil motor driven precision positioning stage is presented.The platform has two degrees of freedom.It is mainly composed of an upper stage and four vertical support links.In the upper stage,the double parallel four-bar linkages mechanisms are symmetrically arranged to realize decoupling and large motion range.The hook compliant series mechanism used as vertical support links is designed to guarantee excellent out-of-plane stiffness for heavy payload.The stage can be decoupled and achieves a large motion.Finite element analysis is also carried out for the platform.In the section of identification,hysteresis model and dynamic model of the system is built based on the system characteristics.Then the coding method,fitness function and adaptive operators of genetic algorithm has been designed.A real-coded adaptive genetic algorithm is adopted to identify the dynamic model and hysteresis in number simulation.At last,the experiment of identification is carried out and the parameters in dynamic model and hysteresis model are identified.In the section of control,as the hysteresis characteristic have a bad influence on the positioning accuracy of precision positioning system,in this research the feedforward sliding mode controller is designed based on the dynamic model and hysteresis model.After the design of the controller,a series of control experiments are carried out with dSPACE real-time control board.And then feedforward PID controller are appied to the system in order to compare with the sliding mode control.Experimental results show that the feeddorward sliding mode controller design in this paper is better than the feedforward PID control method.