Research On 3-UPU Parallel Mechanism Control System Based On PMAC

The parallel mechanism that composed of multiple parallel chains is a closed-loop system while compared with the serial mechanism has high rigidity,strong bearing capacity,high precision,fast response speed,motion performance and many other advantages,so that the parallel mechanism has been widely researched and applied.The control system is the core part of the parallel mechanism,but also determines the degree of parallel mechanism performance.Based on the 3-UPU parallel mechanism as the research object,and its control system are analyzed and studied in detail.This paper started from the following aspects:(1)Based on the principle of mechanism and kinematics,the mechanism of parallel mechanism is analyzed.The three-dimensional solid model of 3-UPU parallel mechanism is constructed by using Solidworks,and the degree of freedom is calculated by the formula of spatial degree of freedom.At the same time,the position inverse solution model and the position forward solution model of the 3-UPU parallel mechanism are derived by kinematics analysis.Finally,the workspace of the mechanism is analyzed and solved by using the kinematics inverse solution model.(2)The control system model of 3-UPU parallel mechanism is constructed by Matlab and Solidwork.Firstly,the model of the mechanism is optimized,then the SimMechanics model of 3-UPU parallel mechanism is constructed by using the interface transformation of the two softwares.The traditional PID control model and fuzzy PID control model are established by Simulink,and the quality of the two control schemes in response speed and trajectory tracking error are compared by simulation results.(3)According to the characteristics of parallel mechanism,the acceleration and deceleration curves of trapezoid curve,exponential curve and S-type curve are analyzed by differential method,and the motion laws of these three kinds of velocity curves are deduced.The S-type velocity curve is tested by PMAC motion control card,which verifies the smoothness of the mechanism in the process of starting,stopping and accelerating and decelerating under the control mode of S-type acceleration and deceleration curve.(4)The experiment platform of 3-UPU parallel mechanism control system is built,including motion control unit,servo unit,security unit installation and hardware parameter configuration.Finally,the system is debugged through the built experimental platform.Then the trajectory motion experiment of the system is carried out.