Task frame estimation during model-based teleoperation for satellite servicing

Abstract

Model-based teleoperation is suitable for systems with large communication delay because the operator interacts with a model of the task while the remote robot uses sensor-based control to replicate that interaction on the physical system. When the model geometry is accurately known, it is only necessary to register it to the remote physical system. If registration errors can be detected during the task, it is possible to update the local task frame (as in model mediated teleoperation) or the remote task frame. This paper proposes the latter approach for the case of telerobotic satellite servicing where the remote (on-orbit) robot cuts the tape that secures the patch of insulation covering the satellite access panel. This task can be modeled as sliding a tool along a planar surface (or one that is locally planar). The remote task frame is used by a hybrid position/force controller to maintain contact with the planar surface. Registration errors, however, can affect the orientation of the cutting tool and cause cutting failures. Therefore, the registration is updated during the task by using position measurements under the effect of hybrid control. The contributions of this paper are in the application of this method to teleoperation, where it must handle user-specified motions, and in the experimental verification during cutting, where compliance of the environment must be estimated and taken into account.