GA Based Adaptive Singularity-Robust Path Planning of Space Robot for On-Orbit Detection

As a new on-orbit detection platform, the space robot could ensure stable and reliable operation of spacecraft in complex space environments. The tracking accuracy of the space manipulator end-effector is crucial to the detection precision. In this paper, the Cartesian path planning method of velocity level inverse kinematics based on generalized Jacobian matrix (GJM) is proposed. The GJM will come across singularity issue in path planning, which leads to the infinite or incalculable joint velocity. To solve this issue, firstly, the singular value decomposition (SVD) is used for exposition of the singularity avoidance principle of the damped least squares (DLS) method. After that, the DLS method is improved by introducing an adaptive damping factor which changes with the singularity. Finally, in order to improve the tracking accuracy of the singularity-robust algorithm, the objective function is established, and two adaptive parameters are optimized by genetic algorithm (GA). The simulation of a 6-DOF free-floating space robot is carried out, and the results show that, compared with DLS method, the proposed method could improve the tracking accuracy of space manipulator end-effector.

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Trajectory Planning Based on Screw Theory with Consideration of the Optimal Berth Position for a Space Robot

International Journal of Aerospace Engineering ◽

10.1155/2019/1034705 ◽

2019 ◽

Vol 2019 ◽

pp. 1-14

Author(s):

Yong Wang ◽

Ying Liao ◽

Kejie Gong

Keyword(s):

Trajectory Planning ◽

Screw Theory ◽

Optimization Method ◽

Euler Method ◽

Space Robot ◽

Optimization Strategy ◽

Generalized Jacobian ◽

End Effector ◽

Planning Strategy ◽

Exponential Formula

Trajectory planning is a prerequisite for the tracking control of a free-floating space robot. There are usually multiple planning objectives, such as the pose of the end-effector and the base attitude. In efforts to achieve these goals, joint variables are often taken as exclusive operable parameters, while the berth position is neglected. This paper provides a novel trajectory planning strategy that considers the berth position by applying screw theory and an optimization method. First, kinematic equations at the position level are established on the basis of the product of exponential formula and the conservation of the linear momentum of the system. Then, generalized Jacobian matrices of the base and end-effector are derived separately. According to the differential relationship, an ordinary differential equation for the base attitude is established, and it is solved by the modified Euler method. With these sufficient and necessary preconditions, a parametric optimization strategy is proposed for two trajectory planning cases: zero attitude disturbance and attitude adjustment of the base. First, the berth position is transformed into the desired position of the end-effector, and its constraints are described. Joint variables are parameterized using a sinusoidal function combined with a five-order polynomial function. Then, objective functions are constructed. Finally, a genetic algorithm with a modified mutation operator is used to solve this optimization problem. The optimal berth position and optimized trajectory are obtained synchronously. The simulation of a planar dual-link space robot demonstrates that the proposed strategy is feasible, concise, and efficient.

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Inverse kinematics of free-floating space robots with minimum dynamic disturbance

Robotica ◽

10.1017/s0263574700018531 ◽

1996 ◽

Vol 14 (6) ◽

pp. 667-675 ◽

Cited By ~ 7

Author(s):

Fengfeng Xi

Keyword(s):

Inverse Kinematics ◽

New Method ◽

Space Robots ◽

Simple Fact ◽

Generalized Jacobian ◽

Space Manipulator ◽

End Effector ◽

Dynamic Disturbance ◽

Space Manipulators

In this paper a new method is presented for solving the inverse kinematics of free-floating space manipulators. The idea behind the method is to move the space manipulator along a path with minimum dynamic disturbance. The method is proposed to use the manipulator Jacobian instead of the generalized Jacobian of the spacecraft-manipulator system. This is based on the simple fact that, if the space manipulator moves along the so-called Zero Disturbance Path (ZDP), the spacecraft is immovable. As a result, the space manipulator can in this case be treated as a terrestrial fixed-based manipulator. Hence, the motion mapping between the joints and the end-effector can be described directly by the manipulator Jacobian. In the case that the ZDP does not exist, it can be shown that the solutions obtained by the proposed method provide a path with minimum dynamic disturbance.

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The establishment and verification of kinematic equation of all link centroid of the manipulator mounted on a satellite

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1177/0954410018763926 ◽

2018 ◽

Vol 233 (5) ◽

pp. 1801-1819

Author(s):

Hongwen Zhang ◽

Zhanxia Zhu ◽

Biwei Tang ◽

Jianping Yuan

Keyword(s):

Angular Velocity ◽

Path Planning ◽

Space Robot ◽

Kinematic Equation ◽

End Effector ◽

Floating Base ◽

Kinematic Relationship ◽

Fixed Base ◽

Angular Velocities ◽

Specific Working

When using space robot to capture target like failed satellite, the force impulse between the target and the end-effector of space robot will load the base satellite with additional momentum abruptly. When capture happens, the pre-impact configuration can influence augmentations of partial momentum of the base and the manipulator. In order to realize a pre-impact configuration, which can reduce the partial momentum augmentations, the control of all link centroid together with end-effector by path planning is very important. In this paper, we establish a basic velocity kinematic equation for all link centroid, which describes the basic linear kinematic relationship between the linear velocity of all link centroid and linear and angular velocities of the base, joint angular velocity of the manipulator, where this basic velocity kinematic equation can be developed into kinematic equations for all link centroid under different kinds of working modes such as free-floating working mode. All link centroid can be controlled by path planning with this equation. Besides, velocity kinematic equation for all link centroid of space robot under a specific working mode is similar to the velocity kinematic equation for end-effector of space robot under the same working mode, so all link centroid can be controlled together with end-effector by path planning. We have derived velocity kinematic equations for all link centroid of space robot with a free-floating base and a fixed base. Both of them are verified by numerical simulations. The motions of position and attitude of the base and the manipulator end caused by all link centroid motion are also shown by simulation study. We also realize the simultaneous path tracking of all link centroid and end-effector for a fixed base space robot.

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Compliant Grasp Strategy for Three-fingered Space Robot End-effector

ROBOT ◽

10.3724/sp.j.1218.2011.00427 ◽

2011 ◽

Vol 33 (4) ◽

pp. 427-433 ◽

Cited By ~ 2

Author(s):

Qingli ZHANG ◽

Fenglei NI ◽

Yingyuan ZHU ◽

Jin DANG ◽

Hong LIU

Keyword(s):

Space Robot ◽

End Effector

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Space robot motion path planning based on fuzzy control algorithm

Journal of Intelligent & Fuzzy Systems ◽

10.3233/jifs-219094 ◽

2021 ◽

pp. 1-8

Author(s):

Baoyu Shi ◽

Hongtao Wu

Keyword(s):

Path Planning ◽

Fuzzy Control ◽

Obstacle Avoidance ◽

Control Algorithm ◽

Space Robot ◽

Robot Motion ◽

Robot Path Planning ◽

Behavior Based ◽

Fuzzy Control Algorithm ◽

Robot Path

Path planning technology is one of the core technologies of intelligent space robot. Combining image recognition technology and artificial intelligence learning algorithm for robot path planning in unknown space environment has become one of the hot research issues. The purpose of this paper is to propose a spatial robot path planning method based on improved fuzzy control, aiming at the shortcomings of path planning in the current industrial space robot motion control process, and based on fuzzy control algorithm. This paper proposes a fuzzy obstacle avoidance method with speed feedback based on the original advantages of the fuzzy algorithm, which improves the obstacle avoidance performance of space robot under continuous obstacles. At the same time, we integrated the improved fuzzy obstacle avoidance strategy into the behavior-based control technology, making the avoidance become an independent behavioral unit. Divide the path planning into a series of relatively independent behaviors such as fuzzy obstacle avoidance, cruise, trend target, and deadlock by the behavior-based method. According to the interaction information between the space robot and the environment, each behavior acquires the dominance of the robot through the competition mechanism, making the robot complete the specific behavior at a certain moment, and finally realize the path planning. Furthermore, to improve the overall fault tolerance of the space, robot we introduced an elegant downgrade strategy, so that the robot can successfully complete the established task in the case of control command deterioration or failure of important information, avoiding the overall performance deterioration effectively. Therefore, through the simulation experiment of the virtual environment platform, MobotSim concluded that the improved algorithm has high efficiency, high security, and the planned path is more in line with the actual situation, and the method proposed in this paper can make the space robot successfully reach the target position and optimize the spatial path, it also has good robustness and effectiveness.

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