Research On Trajectory Planning Of The Cable-Driven Continuum Robot

Cable-Driven Continuum Robots(CDCRs)are a kind of multi Degree-of-Freedom(DOF)mechanism which can realize continuous deformation by using multiple light driving cables.Due to the continuous deformation property of the CDCR,the motion is easily affected by deformation of the cable,vibration of supporting mechanism and other factors.The kinematic trajectory planning can effectively avoid the above-mentioned problem.Therefore,it is very important to study its trajectory planning for improving the motion accuracy of the CDCR.Based on a designed CDCR with four Cable-Driven Segments(CDSs)supported by hydraulic hose,the kinematics model of the CDCR is built to study the trajectory planning and optimization methods,the pose planning and other issues.Firstly,the configuration designs of the CDS and the CDCR with four CDSs are studied.Based on the piecewise constant curvature and the two-parameter local Product of Exponential(POE)formula,the kinematic modeling methods of the CDS and the CDCR are studied.The Monte Carlo algorithm is used to simulate and analyze the point cloud image of the workspace for the CDCR,which lays a theoretical foundation for the subsequent trajectory planning of the robot.Secondly,the trajectory planning method of the CDCR is studied,including the joint space and the Cartesian space.In joint space,the trajectory planning of the CDCR is achieved by using the method of quintic polynomial and quintic B-spline interpolation.In Cartesian space,the trajectory planning method of the CDCR on the basis of space linear interpolation,circular arc interpolation and B-spline interpolation is studied.The effectiveness of the joint space and Cartesian space trajectory planning methods is verified by relevant simulation and experiment.In order to further improve the effect of trajectory planning,the optimization method of the trajectory planning is studied.A Particle Swarm Optimization(PSO)algorithm based on adaptive inertia weight is proposed.The optimization mathematical model with time as the optimization objective is established and solved.The Matlab simulation results show that the method can improve the continuity of trajectory planning and save the running time of the CDCR.Finally,in order to ensure the synchronization of position and orientation changes during the motion process of the CDCR,a Bessel curve pose interpolation algorithm based on Lie group method is proposed to realize the simultaneous interpolation and trajectory planning of position and orientation in space.The simulation results show that the pose interpolation method has good continuity.The stability and accuracy of the CDCR are improved through the simultaneous trajectory planning of position and orientation.