Master-Slave Control Method with Force Feedback for Grasping Soft Objects using a Teleoperation Construction Robot

Abstract

The purpose of this research was to develop a control method that would provide an operator with a noticeable and reasonable sense of reaction force during slow grasping of a soft object. We examined a master-slave control system for a teleoperation construction robot comprised of two joysticks as the master that are used to manipulate the object from a remote location, and an excavator with four degrees of freedom consisting of a fork glove, swing, boom, and arm as the slave. In remote control systems, the operator must feel a reasonable sense of force from the fork glove feedback. We previously proposed a variable-gain velocity control system but found that the reaction force was insufficient and often undetectable to operators' sensory receptors in the initial stage of the grasping task, and the reaction force did not appear as a stepwise relation to the increased driving force when grasping a foam block at a slow speed. Based on these earlier problems, we proposed an improved method that provides a noticeable torque and variable gain that changes with the hardness of the task object. Its effectiveness was verified by a concrete block, tire, and sponge foam block grasping experiment.