Research On Trajectory Planning And Force Position Control Of Adaptive Stretch Bending

Stretch-bending parts have the advantages of high precision and good forming quality,and are widely used in automobiles,high-speed rail,aerospace and other fields.At present,force control or displacement control is often used in stretch bending machines,which cannot realize force/position synchronous control,resulting in low precision of formed parts and a large amount of debugging consumables.Taking the pull-bending machine as the research object,combined with the impedance control technology,a digital model of the pull-bending machine was established,the pull-bending trajectory was planned,and the force/position control simulation model of the pull-bending machine was established.On this basis,based on NX MCD and TIA Portal,a virtual experimental platform for tensile bending mechanism was established to verify the feasibility of the force/position control model of the tensile bending mechanism.The specific research work of this paper is as follows:(1)Based on the configuration of stretch bending mechanism of stretch arm type stretch bending machine,the kinematic model and kinematic simulation model of stretch bending mechanism were established,and the correctness of kinematic model of stretch bending mechanism of stretch bending machine was verified.(2)Based on the stretching and bending process of the tension-bending machine,the calculation function of the clamp trajectory is deduced.On this basis,the joint space and Cartesian space trajectory planning algorithms are compared and studied.According to the clamp trajectory of the stretch-bending mechanism,a joint space-based stretch-bending mechanism trajectory planning algorithm is established.(3)According to the principle of impedance control,the impedance control model of the tension-bending mechanism of the tension-bending machine is established,and the advantages and disadvantages of the force-based impedance control and the position-based impedance control are compared and analyzed.At the same time,the reasons for the steady-state error of the impedance control model are analyzed,and an adaptive control algorithm is introduced to reduce the steady-state error of the impedance control.(4)The impedance control model and adaptive impedance control model of the stretch-bending mechanism of the stretch-bender were built,and the force/position control model of the stretch-bending mechanism of the stretch-bender was simulated and analyzed to verify the feasibility of the adaptive impedance control algorithm to reduce the steadystate error.According to the simulation results,the influence of different impedance control parameters on the impedance control is analyzed.On this basis,based on the NX MCD and TIA Portal software systems,a virtual test platform for the stretch-bending mechanism of the stretch-bender was established,and the force/position control experiment was carried out to verify the feasibility of the force/position control algorithm for the stretch-bending mechanism of the stretch-bender.