Impact modeling and estimation for multi-arm space robot while capturing tumbling orbiting objects

This paper presents impact modeling of a multi-Arm robotic system mounted on a service satellite while capture of tumbling orbiting objects. A robotic system with multiple arms would be capable of capturing multiple objects simultaneously. Further when satellite is in broken state or does not have provision for grapple and tumbling, the interception is very difficult. In such cases, interception using multi-Arm robotic system can be appealing as this will increase the probability of grasp in comparison to single-Arm robot. In this paper, three phases of the capturing operation, namely, approach, impact and post impact have been modeled. In the approach phase, the end-effectors' velocities are designed same as that of the grasping point on the target in order to avoid high impact forces. But in practice, there will be a nonzero relative velocity between the end effector and the grapple point, leading to an impact. In the impact phase, a framework is developed to estimate the changes in the generalized velocities caused by the impact. In post impact phase, these velocities are used as an initial condition for the post impact dynamics simulations of the combined robotic system and target object. Efficacy of the framework is shown using a dual-Arm robot mounted on a service satellite performing capturing operation for two tumbling objects.