Research On Forgings Force Perception And Prediction Method Based On Manipulator Clamping Mechanism

Manufacturing industry is the foundation of a nation,the instrument of revitalizing a nation,and the foundation of a strong nation.Free forging is an important part of the manufacturing industry and the main production method for heavy forgings.Forging manipulator is mainly used for clamping and feeding of free forging workpieces,including single manipulator forging production mode and dual manipulator forging production mode.During the forging production process,the deformation resistance of the forging caused by deformation and the coupling force caused by the uncoordinated movement of the two machines will be transmitted to the manipulator body.That causes the change of the forging deformation direction,and even the failure of the manipulator body.This requires the control system to introduce the active force control to provide the necessary buffer.The key to the active force control is how to obtain the external force as the feedback input.Therefore,it is necessary to research an external force perception method under severe conditions and realize the external force vector prediction.Aiming at the problem that the external force of forging manipulator cannot be measured directly in the forging process,the 20 k N forging manipulator of the “5MN rapid forging hydraulic unit pilot test platform” of Yanshan University is used as the research object to conduct force perception and prediction method research on the force of the forging.It provides theoretical and technical support for the coordinated compliance control of free forging.The main research contents of this dissertation are as follows:(1)Taking the clamping mechanism of the forging manipulator as the object,the mapping relationship between the diameter of forging clamping end and the pose of each component was deduced.Based on two special clamping states of clamp,horizontal and vertical,the mapping relationship between the gravity of the forging and the output force of the driving hydraulic cylinder under any clamping state was analyzed.According to the force balance relationship,the mapping relationship between forging force and hinge force of clamping mechanism is established,and the force perception model of forging based on the characterization of clamping mechanism is comprehensively constructed.(2)Based on the force perception model of forging,the change rule of the clamping mechanism hinge point force when the diameter of the forging,the rotation angle of the clamp and the forging force change was studied.the sensitivity of hinge point force to forging force response is analyzed,and the force characteristic points of the hinge point were selected.A scaled-down experimental prototype of the clamping mechanism and an ADAMS static simulation model were established,and the correctness and effectiveness of the force perception model was verified by the prototype experimental results and static simulation results.(3)Based on the support vector machine regression prediction algorithm,the forging force prediction model was established.In order to improve the accuracy of the support vector machine regression prediction,a prediction model parameter optimization method combining grid search and cross validation was added.The force prediction accuracy was taken as the measurement index,and the force prediction research of different combinations of force characteristic points was carried out.The high accuracy force prediction with the least force characteristic point was realized.