Experimental Studies on Design and Position Control of a Foldable Robot Arm for a Hybrid Robot Manipulator

This paper presents the design and control of a hybrid robot arm that has a foldable arm at the end effector. The foldable arm is actuated by wires driven by a single motor and springs. The steel wire driven by a motor connects the ring structure to the body of the folding robot arm in zigzag patterns to regulate the length of the system and to compensate for some of the gravitational force. The torsional springs are implemented on the joints of scissored links to release the link. The foldable arm has some characteristics of saving work space with its changeable length and less stiffness than rigid robot arms to reduce a damage to an object. The foldable arm is configured as the scissored link structure to realize the foldable mechanism. Position control of the foldable arm is implemented to check its control functionality of folding and releasing.