Abstract
In this paper, a weighted additional deviation velocity on the basis of the gradient projection (GP-WADV) method is proposed to solve obstacle avoidance problems of the redundant manipulator under the condition of known end-effector trajectory. The GP-WADV method aims to find the point closest to the obstacle on the link of the manipulator and attach the additional deviation velocity with weighting factors to the point on the basis of the gradient projection method. Utilizing multi-solution characteristics of redundant robots, obstacle avoidance control parameters related to the distance between obstacles and links are proposed according to the gradient projection method for solving inverse kinematic solution. Moreover, a weighted method is adopted to adjust the weighting factors of the primary motion velocity and the additional motion velocity when the link approaches the obstacle, so as to obtain the joint angle solutions more quickly and accurately. The GP-WADV method can ensure that the manipulator can avoid obstacles smoothly without turbulence and solve the highly nonlinear relationship between the position of the manipulator and the joint coordinate, which has the advantages of small amount of calculation, more flexible and convenient real-time control. The advantages of the proposed GP-WADV method are proved by simulation and experiments.
Highlights
In recent decades, redundant manipulators have played a more and more important role in numerous fields of engineering applications [1]–[4], which possessing more degrees-offreedom (DOF) in joint space than workspace and offering increased control flexibility for complicated tasks
Traditional obstacle avoidance methods include the free space method based on the C-space method, the artificial potential field method based on the penalty function, the additional deviation velocity method, the gradient projection method and so on
GP-WADV method can ensure that the manipulator can avoid obstacles smoothly without turbulence and solve the highly nonlinear relationship between the position of the robot arm and the joint coordinates, which has the advantages of small amount of calculation, more flexible, more secure and convenient real-time control
Summary
Redundant manipulators have played a more and more important role in numerous fields of engineering applications [1]–[4], which possessing more degrees-offreedom (DOF) in joint space than workspace and offering increased control flexibility for complicated tasks. Jin et al [29], [30] performed the path planning of a robot in real time by establishing a dynamic neural network These methods based on machine learning or numerical iterative methods have the advantage of path smoothing and fast calculation. In order to solve the above problems, this paper proposed a weighted additional deviation velocity on the basis of the gradient projection (GP-WADV) method to solve obstacle avoidance problems of the redundant manipulator under the condition of known end-effector trajectory. GP-WADV method can ensure that the manipulator can avoid obstacles smoothly without turbulence and solve the highly nonlinear relationship between the position of the robot arm and the joint coordinates, which has the advantages of small amount of calculation, more flexible, more secure and convenient real-time control.
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