Development for an Exoskeleton-Type of Master Device to Improve Operation Convenience

Abstract

For the teleoperation of dual-arm robots that perform various tasks, the existence of a control device with high degree of freedom is indispensable. In particular, when precise work is required, additional information such as force feedback is very helpful to the operator. In transmitting this force information, a master device in the form of an exoskeleton having a large contact area with a human body may be one solution. This study aims to improve the wearer's convenience of operation during teleoperation using a master device. First, This study proposes an optimal design method for the 7 degrees of freedom (DOF) exoskeleton systems. The proposed method optimizes the kinematic parameters by using kinematic performance indices related to the dexterity of the human and exoskeleton system. The manipulability ellipsoid is a representative index to check the dexterity of the robot, and we intend to make an objective function by utilizing it. After deriving the parameters affecting the performance of the master device through the performance index, optimization was performed using a genetic algorithm. Next, to overcome the problems caused by misalignment between the exoskeleton system and the human body, additional mobility was given to fixation. All configurable mobility combinations were derived for the 7-degree-of-freedom exoskeleton system, and the final mobility combination was selected based on practical applicability. In order to verify the effect of applying the fixation mechanism, an experiment was conducted to measure the interaction force occurring during the operation of the exoskeleton system. As a result of T-test, a significant result of p ≤ 0.05 was obtained. Finally, a human-robot interaction controller for driving the exoskeleton system was designed, and position-rate control was applied for natural work-space mapping. In order to evaluate the convenience of operation of the developed controller, a teleoperation experiment was conducted, and the mission could be performed in a short time compared to the position control mapping and rate control mapping.