Research On Visual Calibration And Pose Control Of A Cable Driven Parallel Robot

As a kind of practical parallel robot,the cable-driven parallel robot can be used in various scenarios such as rehabilitation medical treatment,multimedia photography,and cavity testing.It has broad application prospect.Compared with the traditional parallel robot,it has the advantages of low manufacturing cost,strong reconfiguration and wide movement space.In this paper,the 8-cable and 6-degree-of-freedom cable-driven parallel robot is taken as the research object,focusing on the study of visual calibration and pose control.The main research results are as follows:(1)A camera calibration algorithm that automatically and accurately extracts the center of marker point is proposed,which reduces the eccentricity error generated during calibration,and uses the idea of iterative projection to further optimize the algorithm.Taking the projection error as the judgment standard,this algorithm has improved accuracy compared with the commercial camera calibration software of Microvision and other companies,which ensures the accuracy of subsequent visual calibration;(2)A visual calibration compensation method based on the initial pose of the end-effector is proposed.Since the end-effector would have an offset at the initial stage,the initial pose should be corrected by changing the length of the cable.After the camera calibration is completed,the binocular camera is used to take the relevant pictures,and then the 3D position and pose are measured.The cable length is calculated and automatically compensated by the pose inverse solution.Experimental results show that the precision of visual measurement is similar to that of the motor encoder used in the experiment platform,and accurate calibration can be achieved;(3)The experimental platform of 8-cable and 6-degree-of-freedom cable-driven parallel robot is built,and the experimental research is carried out.The forward and inverse solutions and PID control algorithm of the cable-driven parallel robot are analyzed.The kinematics simulation and fuzzy adaptive PID pose control simulation are realized by using MATLAB Simulink model,and space linear motion control experiments are carried out combined with visual calibration.Experimental results show that the pose control system is feasible.