Abstract
This paper presents an adaptive caging configuration design algorithm of the hyper-redundant manipulator for dysfunctional satellite pre-capture. Taking advantages of the extreme flexibility and hyper-redundancy, the hyper-redundant manipulator wraps its whole body around the dysfunctional satellite to restrain its motion without requiring grappling points and accurate information. However, the hyper-redundancy also makes the caging configuration design more complicated and challenging. In this paper, the dynamic sequential caging following algorithm based on rapidly-exploring random tree algorithm is proposed to search the caging configuration in real-time. First, according to the discretized caging trace, which is twining around the grasped object and selected based on the caging conditions, the joints of the hyper-redundant manipulator are divided into several groups in advance. Then, the joint angles are searched group by group to realize the match of the discretized caging trace by the hyper-redundant manipulator. As a result, the configuration between the grasped object and the hyper-redundant manipulator satisfies the caging conditions. The main advantages of the proposed caging motion planning algorithm lie in the avoidance of the inversion and the efficiency of computation. Finally, the pre-capture of two dysfunctional satellites with different shapes using a twenty universal joint manipulator is implemented, and the simulation results verify the efficiency of the proposed method.
Highlights
Due to running out of fuel, attitude and orbit control system failure, task termination, and so on, there are more and more dysfunctional satellites in space
The dynamic sequential caging following algorithm based on rapidly-exploring random tree (RRT) algorithm is proposed to search caging configuration of the hyper-redundant manipulator in real-time in this paper
In order to guarantee the effectiveness of the caging and the operability of the hyper-redundant manipulator, the caging trace is discretized into a sequence of critical points connected by caging edges
Summary
Due to running out of fuel, attitude and orbit control system failure, task termination, and so on, there are more and more dysfunctional satellites in space. Similar to the numerical methods, with the increase of the number of DOFs, the size of the training set will change significantly that increases the computating complexity To solve this problem, the dynamic sequential caging following algorithm based on rapidly-exploring random tree (RRT) algorithm is proposed to search caging configuration of the hyper-redundant manipulator in real-time in this paper. Remark 1: The caging trace calculated here is ideal because it perfectly matches the geometry of the grasped object, which means that the hyper-redundant manipulator does not need to adjust its caging configuration to form a firm capture. These attachments contribute to form a more stable caging configuration because of the additional restraints offered by them. All the caging traces form a set as shown in (5). η is a such trace that can restrain the motion of the grasped object
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