Research And Application Of Microgripper With Hybrid Force/Position Control Function

As an important tool for micro-operation and micro-assembly,micro-gripper is widely used in biomedical,semiconductor processing,optical precision processing and other fields.The rapid development of the above fields has put forward higher requirements for the performance of micro-gripper.How to achieve a larger clamping range,higher clamping accuracy and more controllable clamping process has become the key of microoperation and micro-assembly.In this paper,a dual-drive micro-gripper with high bilateral independent motion and large stroke is proposed to meet the clamping requirements of large stroke,high precision and self-adaptive target position.The gripper uses two piezoelectric stick-slip platforms as driving elements and integrates the force feedback function.In order to meet the requirements of high clamping accuracy and high force-volume ratio,a set of single-drive micro-gripper based on flexible mechanism was proposed.Considering the characteristics of high displacement precision,large stroke and small output force of piezoelectric stick-slip platform,Innovatively combine the flexible displacement shrink mechanism and piezoelectric stick-slip platform to improve the output positioning accuracy on the basis of the precision of piezoelectric stick-slip platform.In this paper,the structure design,modeling analysis and simulation of the two clamping arms are carried out to ensure that they are easy to drive and have appropriate displacement and clamping force output.In this paper,according to the characteristics of the clamp arm a suitable force sensor is selected to build the acquisition circuit.The influence of the force point on the force acquisition is eliminated by using the double strain gauge acquisition method.The calibration platform is designed and the calibration method of clamping force is optimized to ensure the measurement of clamping force is more accurate and effective.The upper computer interface of the clamping platform is written by C++,and the clamping process and clamping algorithm are designed.The clamping flow,right arm position control and left arm PI impedance force/position hybrid control algorithm are proposed for the dual-drive micro-gripper.A feedback control algorithm of position and gripper control is proposed for single drive micro gripper.The clamping algorithm was simulated by SIMULINK to verify its feasibility.Finally,a clamping performance test platform is designed for the clamping process.The position control and force/bit hybrid control ability of dual-drive micro-gripper and the position and force feedback control of single-drive flexible micro-gripper were tested.Experimental results show that the position control and force control of the two grippers have good precision.The maximum stroke of the dual-driver gripper is 16mm,the maximum absolute position deviation is 120nm within the stroke of 0.5mm,and the error range is 0.25±0.175μm.The maximum clamping force is 1.5N,the error distribution of the clamping force is between 0±6mN under PI impedance control,and the tracking of the clamping force can be basically completed within 1s.The maximum stroke of the single-driver gripper is 238.8μm,the maximum absolute position deviation is 50nm within 0.05mm stroke,the error interval is 0.002±0.03μm,the maximum clamping force is 0.5N,the clamping force confidence interval is-2±4mN.