Abstract

Hyper-redundant manipulators with multiple degrees of freedom have special application prospects in narrow spaces, such as detection in small spaces in aerospace, rescue on-site disaster relief, etc. In order to solve the problems of complex obstacle avoidance planning and inverse solution selection of a hyper-redundant robot in a narrow space, a cubic B-spline curve based on collision-free trajectory using environmental edge information is planned. Firstly, a hyper-redundant robot composed of four pairs of double UCR (Universal-Cylindrical-Revolute) parallel mechanisms (2R1T, 2 Rotational DOFs and 1 Translation DOF) in series to realize flexible obstacle avoidance motion in narrow space is designed. The trajectory point envelope of a single UCR and the workspace of a single pair of UCR in Cartesian space based on the motion constraint boundaries of each joint are obtained. Then, the constraint control points according to the edge information of the obstacle are obtained, and the obstacle avoidance trajectory in the constrained space is planned by combining the A* algorithm and cubic B-spline algorithm. Finally, a variety of test scenarios are built to verify the obstacle avoidance planning algorithm. The results show that the proposed algorithm reduces the computational complexity of the obstacle avoidance process and enables the robot to complete flexible obstacle avoidance movement in the complex narrow space.

Highlights

  • IntroductionWith the development of aerospace technology, the demand for on-orbit services such as maintenance of space equipment and fuelling has become more and more urgent

  • Received: 29 December 2021With the development of aerospace technology, the demand for on-orbit services such as maintenance of space equipment and fuelling has become more and more urgent.In order to reduce costs and improve the efficiency of astronauts working outside the cabin, many countries or communities have adopted space robots [1] as an important development direction of spacecraft on-orbit services

  • Three degrees-of-freedom (DOFs) parallel mechanisms have high accuracy and large loading capacity. This part concentrates on the Kinematics modeling and workspace analysis of UCR parallel mechanism

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Summary

Introduction

With the development of aerospace technology, the demand for on-orbit services such as maintenance of space equipment and fuelling has become more and more urgent. Most continuous snake robots achieve passive environmental adaptability through the flexibility of materials or structures [16,17], to achieve the desired position in a complex environment This type of robot has low positioning accuracy under load and is hard to achieve accurate control in a small space [18]. Based on the mechanical structure, the MDA + RRT algorithms is proposed for path planning considering the maximum deflection angle of joint This method can be applied to the planning of small spaces, it cannot control the position of the fuselage of each cell of the continuum, and does not consider whether the envelope of the fuselage will collide with the environment. Solve the pose of the robot arm through the UCR parallel joint drive equation, with high accuracy and fast efficiency

Kinematics Modeling and Workspace Analysis of UCR Parallel Mechanism
Introduction of UCR Parallel Mechanism
Kinematics Modeling of UCR Parallel Mechanism
Workspace Analysis Based on Simulation
Kinematics Modeling of the Manipulator
Kinematics Modeling of Double-UCR Parallel Mechanisms
The Tip-Following B-Spline Path Planning
Simulations and Experiments
Conclusions
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