Optimal Path Planning and Static Obstacle Avoidance for a Dual Arm Manipulator Used in On-Orbit Satellite Servicing

Abstract

Space robotics is one of the key technologies for on-orbit satellite servicing. A satellite in an orbit can stop working because of several reasons such as aging, difficulty in deploying solar array, inadequate amount of fuel, etc. If a service provider satellite can correct the problem, then the useful lifetime of the satellite can be increased. In this paper, a satellite servicing robotic system is considered in which, the client is a satellite, which has failed in its functions and the chaser satellite is the service provider, which has two robotic arms, one is to hold the satellite and the other is for repairing the client. The focus of this paper is on the optimal path planning of the dual arm manipulator in the service provider for capturing and repairing the client. Kinematic and dynamic modelling of the dual arm manipulator is considered. The dynamic equations are derived using the conventional Euler-Lagrange method, and the inverse kinematics is used to find the joint angles from the known end effector position. The optimal path planning problem is formulated as, to minimize the control effort of the system, with constrained joint angles, angular velocities, and joint torques. The joint angle trajectories considered here are parameterized as polynomials in degrees. A static obstacle avoidance criterion is developed so that any case of collision of the arms with any static obstacle can be avoided.