Rate-to-force control in admittance mode bilateral teleoperation

In this paper we present a new control method for teleoperation, which is particularly suitable for heavy duty hydraulic machines. The master device consists in an admittance mode haptic interface. In free motion operations, the slave velocity is proportional to the force exerted by the human operator on the master. In constrained motion, the force applied by the operator's hand directly commands the force exerted by the slave on the environment. The transition exploits the NTRFC concept (Naturally-Transitioning Rate-to-Force Controller) implemented in an independent control unit located on the slave. The master position follows the slave manipulator position. In this way, a realistic feeling of the operation is provided. The whole control system was applied on a 1 D.o.F. joystick and the slave was computer simulated. In this paper, we report the results of the new system compared with a no-feedback rate control one. Experimental results show 50% reduction in task execution time.