Abstract
An obstacle avoidance and path planning algorithm for a multi-joint manipulator in a space robot is presented in this paper. In this paper, the end-effector of the manipulator is used to capture some special target in a space environment with obstacles. To ensure the safety of the operation, a collision-free path from the initial position to the target position is essential. Therefore, an obstacle avoidance and path planning algorithm based on the Rapidly-Exploring Random Tree (RRT) algorithm and the Forward and Backward Reaching Inverse Kinematics (FABRIK) algorithm is presented in this paper. First, a path planning algorithm based on the Rapidly-Exploring Random Tree (RRT) algorithm is designed for the multi-joint manipulator. Further, a method to generate a random point by artificial guidance is introduced for a higher searching speed. The RRT algorithm can effectively explore the entire workspace and find a feasible path without collision for the end-effector. To calculate the positions of each joint, the Forward and Backward Reaching Inverse Kinematics (FABRIK) algorithm is introduced and improved for the problem of inverse kinematics. The FABRIK algorithm avoids the use of rotational angles or matrices, and instead finds each joint position by locating a point on a line, and thus, it has a low computational cost. Therefore, the improved obstacle avoidance and path planning algorithm can quickly plan a feasible path for the multi-joint manipulator in a space environment with obstacles. A numerical simulation is carried out to analyze the proposed obstacle avoidance and path planning method. It is observed that the method finds a feasible path without collision for the multi-joint manipulator with a low computational cost. These results validated the effectiveness of the proposed method for path planning to avoid the obstacles.
Highlights
In the large-scale spacecraft applications, more attention is paid on the space robot with a multijoint manipulator [1], [2]
The contributions can be highlighted as follows: 1) the Rapidly-Exploring Random Tree (RRT) algorithm is introduced, under which the path planning algorithm can effectively explore the entire workspace, and greatly improve the possibility of searching for the obstacle avoidance paths; 2) in order to calculate the positions of the joints, based on the position of the end-effector, a method for the inverse kinematics problem is designed based on the Forward and Backward Reaching Inverse Kinematics (FABRIK) algorithm, under which the positions of each joint can be calculated with low computational cost
In order to complete the obstacle avoidance and path planning for the space robot with multi-joint manipulator, this paper presents an improved obstacle avoidance and path planning algorithm applied to the multi-joint manipulator
Summary
In the large-scale spacecraft applications (for example, onorbit capture, auxiliary docking and on-orbit maintenance, etc.), more attention is paid on the space robot with a multijoint manipulator [1], [2]. The contributions can be highlighted as follows: 1) the RRT algorithm is introduced, under which the path planning algorithm can effectively explore the entire workspace, and greatly improve the possibility of searching for the obstacle avoidance paths; 2) in order to calculate the positions of the joints, based on the position of the end-effector, a method for the inverse kinematics problem is designed based on the FABRIK algorithm, under which the positions of each joint can be calculated with low computational cost. A collision-free path from the initial position to the target position is the basic guarantee to accomplish the mission For this reason, this paper presents a path planning algorithm for the space robot with a multi-joint manipulator. Where, rb is the position of the base, ωb is the attitude angular velocity of the base
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