Design And Control Of A Precision Compliant Micro Gripper

As an important tool in high precision micromanipulation,micro gripper directly affects the quality and efficiency of micromanipulation.In order to achieve stable and reliable clamping,a novel micro gripper with asymmetrical structure is designed,structural design is carried out,static and dynamic analysis and control design of this micro gripper systematically,and the experimental platform is built,the performance test and clamping test of the micro gripper are completed.The main research works have shown as follows:A novel micro gripper which has asymmetrical structure has been designed with just one jaw movable.The developed asymmetrical micro gripper is driven using piezoelectric actuator.The main structure of micro gripper is a flexure-based mechanical structure with three-stage amplification which consists of a leverage mechanism,a bridge type mechanism and a parallelogram leverage mechanism,to realize large and robust jaw displacements and parallel jaw grasping.The kinematic,static and dynamic analyses of the micro gripper have been carried out based on Pseudo-rigid-body model and finite element analysis.Equivalent Pseudo-rigid-body model of the micro gripper is established by Pseudo-rigid-body model method,based on the model,kinematic,and static analysis have been carried out,moreover the input stiffness,maximum equivalent stress and natural frequency have been obtained.The static and dynamic characteristics of the micro gripper have been studied by finite element analysis.Displacement / force switching control strategy has been adopted to adjust the motion position and grasping force.A discrete-time sliding model controller is designed to control the position of jaw and the grasping force.A strain gauges is affixed to the bottom of the flexible beam to measure clamping force and obtain force signals.Two laser displacement sensors are used to measure input and output displacement,so that the displacement signal is obtained.The micro gripper is fabricated and experimental platform is built.The main structure is manufactured by wire electro discharge machining technique to ensure geometric accuracy.In order to detect the performance of the micro gripper,several experiments were carried out.Clamp test is performed to test the clamping performance of clamping arm.Characteristic experiment is performed to get natural frequency and displacement amplification.Control experiment is performed to test the step response of displacement and force.The experimental results show that the micro gripper has good performance,and the high precision grasping operation can be realized by the proposed control strategy.