A Control Method of Space Manipulator for Peg-in-Hole Assembly Task Considering Equivalent Stiffness Optimization

Abstract

To meet the control requirements of high precision and high robustness for peg-in-hole assembly tasks, an optimized control method for a peg-in-hole assembly task of a space manipulator is proposed to reduce the system disturbance caused by the change contact status during the assembly process. The first step is to build an equivalent stiffness model, which considers the structure and control characteristics of the space manipulator. Flexibility indices along the assembly direction are then created. On completion of the flexibility indices, the assembly configuration of the manipulator is optimized with the gain of the joint controller. After that, based on the sliding mode impedance control law, the disturbance of contact force is compensated using a zero-sum optimal control compensation strategy. Finally, the correctness and effectiveness of the control method are verified through simulation experiments. The results of the simulation experiments show that the contact force of the space manipulator can be precisely controlled by the method proposed in this paper. Compared with existing methods, the sudden change of contact force and the disturbing force of the base are reduced by 90% and 54%, respectively. A control method of the space manipulator for a peg-in-hole assembly task considering the equivalent stiffness optimization is proposed, which effectively reduces the influence of disturbance caused by contact collision and improves the control robustness of peg-in-hole assembly tasks.

Analysis and Optimization of Motion Coupling for the Coordinated Operation of Flexible Multi-Arm Space Robots

“…The end gripper of each robot arm and the rigid body are in a state of no relative displacement; The entire coordinated operating system of the FMSR is in static equilibrium; The positional deformation generated in the system satisfies the small deformation condition. The solution of the stiffness matrix of the flexible manipulator is given in th ture [13]. The total deformation at frame  e i is the sum of the deformation gener joint flexibility, linkage flexibility, and the servo.…”

“…To establish the virtual grasping coordinate frame Σ oi , frame Σ e i is translated to the origin of Σ o as the virtual grasping point. The solution of the stiffness matrix of the flexible manipulator is given in the literature [13]. The total deformation at frame Σ e i is the sum of the deformation generated by joint flexibility, linkage flexibility, and the servo.…”

“…ABB [12] used the equivalent stiffness model for the real-time compensation of machining deformation. In another study [13], the motion accuracy of the manipulator was improved by establishing and optimizing the stiffness index of the task direction. The authors of [14] sought to find a way to improve the stability and accuracy of the robot system through the force-deformation relationship described by the stiffness matrix.…”

Configuration Optimization for Free-Floating Space Robot Capturing Tumbling Target

“…Due to the characteristics of microgravity, high vacuum, and strong radiation in space, astronauts carrying out space missions will face extremely high risks. Space robots, with their outstanding advantages in terms of strong adaptability to the space environment and freedom from physiological conditions, have gradually become the main force in space exploration [1][2][3]. In recent years, with the continuous development of space exploration, capturing non-cooperative targets has attracted much attention, as the technique is expected to be applied for functions such as the removal of debris from orbit and servicing broken satellites for repair [4][5][6].…”

Design and Analysis of a Novel Floating Docking Mechanism for On-Orbit Refueling

“…At present, an alternative solution is to recover the functioning of dead satellites with on-orbit refueling [3][4][5][6][7], which effectively avoids the problem of dead satellites occupying orbits and extends the life of spacecraft. With the increasing demand for space missions and the complexity of aerospace engineering, on-orbit refueling technology is an urgent requirement among on-orbit service technologies [1,[8][9][10][11].…”