Interest of the dual hybrid control scheme for teleoperation with time delays

It is well known that classical teleoperation schemes are unstable and even useless when time delays become important. In this paper we propose a new concept called "dual hybrid teleoperation scheme" which really improves the ergonomy of a teleoperation system, even with time delays. Thanks to this concept, the operator can exert forces or perform displacements from the "master" to the "slave". These forces are the ones that the human operator wants to apply for the current task. This is possible thanks to a special law coupling the two robots, each of them having an hybrid positionforce control. This scheme also offers kinesthetic feedback, without compromising the stability, even with time delays. So the operator can feel some useful sensations, as "moving feeling". Besides, this scheme allows to split a complex task into subtasks, during which the operator only manages few degrees of freedom. The attention required to perform a given ta~sk is really decreased and the operator can focus on a limited set of degrees of freedom. The experiments done with an system based on this new concept show that it can be apply even if t ime delay becomes superior to few seconds. 1. I n t r o d u c t i o n A robot with autonomous manipulation capabilities does not always allow to solve complex tasks as space assembly or space maintenance tasks, and specially for the fine manipulations involving contact with the environment. It is not always possible in this case to foresee all the necessary actions for solving any task. Owing to the imperfect knowledge of the real world and the complex interaction with the remote environment, an ability of recovery, which can only be brought by a human being, must be introduced. The teleoperation remains the most interesting way for performing work remotely in some applications.