Design of a Reconfigurable Novel Constant-Force Mechanism for Assistive Exoskeletons

Constant-force mechanisms can be used for gravity counterbalance and force regulation. While many constant-force mechanisms have been designed, most of them have a limited range of force adjustment, which brings very limited capability to maintain an equilibrium state when load changes. In this paper, a novel design of reconfigurable constant-force mechanism is proposed. The mechanism is designed from the concept of hinged-lever constant-force mechanism. Through adjusting the configuration parameter, a large adjustment range of the equilibrium state is achieved. Mathematical models are developed to simulate the equilibrium performance changed with configuration parameters. A prototype is constructed and validates the working principle of the novel design, demonstrated with a concept of assistive arm exoskeleton.