Trajectory Planning And Control Of Cable-driven Snake Manipulator

The cable-driven snake manipulator is a kind of continuous robot.As a kind of typical bionic robot,it has good adaptability to the environment.It can move flexibly in unstructured environment and narrow space.Using the rope to drive can put the driving device and controller outside the robot body.This way can reduce the volume and weight of the robot working section effectively to make the structure compact.It can also ensure the reliability of the robot in complex and harsh environment.At present,the cable-driven snake manipulator is widely used in disaster relief,space exploration,maintenance and assembly in narrow space and other fields.Firstly,a cable-driven snake manipulator with 16 degrees of freedom is designed in this paper,The robot has 8 cone sections,uses 24 ropes for driving,and the driving system adopts linear guide mechanism.After the structure is determined,the mass characteristics and position information of each part of the robot are calculated by Creo,and the simulation parameters are set and model is established in MBdyn.Based on the structure design,using the traditional DH method to establish the rod coordinate system of the robot and the forward and inverse kinematics analysis are analyzed,including the kinematics analysis from the driving space to the joint space and the kinematics analysis from the joint space to the operation space.Then solving the workspace of the robot based on the Monte Carlo method.Based on the kinematics analysis,the paper establishes the description method of the manipulator system and carries out the dynamics analysis of the system according to the equivalent wrench and virtual work principle,then establishes a kind of Jacobian matrix solving algorithm from the rope force to joint torque.Based on this,the control model of the cable-driven snake manipulator is built and the control rate what the paper adopts is the calculating moment method,it adopts the quadratic programming to solve the optimization solution of the rope force.In the end,two typical motions of the cable-driven snake manipulator are simulated and analyzed to verify the correctness of the algorithm.In order to solve the problem of the path following when the cable-driven snake manipulator has the feed base,a kind of algorithm for tracking the end track of the cabledriven snake manipulator is designed.First of all,generating the path curve based on the cubic B-spline interpolation method,and to solve each joint center's position of the robot on the path curve under each feed step.Then 16 joints' angles are solved by inverse kinematics.In the end,making the simulation analysis of Trajectory tracking in plane sine and space helix to verify the following effect and the correctness of the algorithm.In addition,an obstacle avoidance trajectory planning algorithm based on artificial potential field method is also designed.The algorithm establishes the gravitational potential field between the robot's endpoint and the target point,the repulsion potential field between the obstacle and the robot.Excluding the angle combination that make the robot collide with the obstacles in all adjacent joint angle combinations that are got by angle search in joint space.In the remaining combination,selecting the joint angle combination with the smallest sum of gravitational potential energy and repulsive potential energy as the next motion angle and the local minimum problem is also solved by establishing virtual target point.In the end,using this algorithm to finish the obstacle avoidance motion control of the cable-driven snake manipulator successfully.