Obstacle Avoidance And Path Planning For A Redundant Manipulator

Redundant manipulator with highly flexibility,fault tolerance and reliability,using its self-motion characteristics can avoid obstacles,avoid singularities and avoid joint limited,it also can optimize the joint torque and so on.According to a seven degree of freedom redundant manipulator,we research the obstacle avoidance and the path planning.We will provide a supported theoretical to the development of the station's robotic arm for China's space technology.The main research contents are as follows:Firstly,this paper introduces a seven DOF redundant manipulator model with a linear guide,found its kinematic model,Analysis its forward kinematics and inverse kinematics.Solve the work space By using the Monte Carlo method,then to pave the way for the later analysis of obstacle avoidance.Built the kinematics equation of seven degree of freedom redundant manipulator,and verify the correctness of the kinematics equation in Matlab.Secondly,In the light of the shock problems for the additional speed deviation theory in obstacle avoidance process,we proposed the improved method.To solve the shock problems caused by a plurality of bars closing to an obstacle,we use the weighted average method based on the multiple distance,and then by adding two parameters to adjust the priority of the main movement and additional movement to make a smooth transition.Using Matlab as the simulation platform,we simulate the redundant manipulator of seven DOF planar to close to a single obstacle and to close to multi-obstacle.And simulate drilling the hole with the seven degrees of freedom of the redundant manipulator.Then we verify the validity of the algorithm.Again,in order to solve the problem of slow convergence and low success rate for the RRT*algorithm,based on the RRT*algorithm,we introduce the two-way searching strategy and path optimization algorithm based on triangle inequality,we propose an improved RRT*algorithm.In the light of the not smooth path problem,we the smooth the path by Bessel curve.The simulation results show that,both in the low dimensional space or high dimensional space,the improved RRT*algorithm has a higher success rate of planning path in the same time,and can quickly converge to the optimal path;the Bessel curve smoothing algorithm can not only to ensure that no collision between manipulator and obstacle,but also make the path smooth,it make the movement of the manipulator more stable.Finally,using the seven degree of freedom redundant manipulator with linear guide as the experimental platform,we verify the effectiveness of the path planning algorithm of improved RRT*and obstacle avoidance algorithm.