Development of a manipulator with an opposed-placement-type ER clutch contributing to collision force reduction

Abstract

In recent years, human and robots have begun to work together in the fields of medical treatment and welfare. In such environments, robots must be designed to operate safely; thus, reducing collision force when collision is occurred with their human colleagues is essential. In this study, a manipulator with opposed-placement-type electrorheological (ER) clutches is designed to reduce the collision force. The main feature of the manipulator is a structure that sandwiches the link between two ER clutches and equips the link with a pneumatic cushion. The input shaft of each clutch is rotated in the opposite direction via a bevel gear and a spur gear from an electric motor. Because the link can be reversed by switching the clutch, the manipulator can operate in high-speed reverse motion. Position control, reverse motion control and collision experiments were performed to test the effectiveness of the manipulator. The reverse motion control experiment revealed that the manipulator can reverse more rapidly than a conventional manipulator, which is only driven by a motor. From the collision control experiment, it was found that the manipulator can reduce the collision force more effectively than the conventional manipulator.