Design of a Foldable Robot Arm for a Hybrid Robot Manipulator

This paper presents the design of a foldable robot arm(FRA) actuated by wires and springs for a hybrid robot manipulator. The arm can be folded actively and extended passively. Folding movement is done actively by pulling wires by a motor and extending is done passively by torsional springs. Selection of torsion springs for each joint is analyzed. Arm pulling mechanism is designed by winding wires. A gear mechanism is designed for one motor to wind all of three cables simultaneously. Actual position control performance is demonstrated by empirical studies to show the feasibility.