Strategies and models for cutting satellite insulation in telerobotic servicing missions

Research on the Robotic Refueling Mission (RRM) addresses techniques that allow us to robotically refuel and service existing satellites in space. In preparation for refueling, it is necessary to cut the tape that binds a patch of satellite insulation (Multilayer Insulation or MLI) over the fuel access port. It is desirable to cut only the tape, leaving the MLI intact, so that the satellite does not incur thermal stress. This task is performed telerobotically, with an operator located at a ground station, and therefore is subject to communication time delays of several seconds. In our approach, the ground-based operator interacts with a simulated environment and his/her desired actions are replicated by the remote (on-orbit) robot a few seconds later. This paper focuses on developing and modeling two effective cutting strategies, with the goal of using the models to predict the forces that should occur during cutting. These models can serve two purposes: (1) to enable the on-orbit robot system to stop if the measured forces are not consistent with the predicted forces, without waiting several seconds for the human operator to discover and react to the problem, and (2) to provide realistic haptic feedback to the operator at the ground station. The strategies and models are validated on a ground-based platform that uses the master console of a da Vinci^® Surgical System to teleoperate a Whole Arm Manipulator (WAM) that emulates the on-orbit robot.