Abstract Rehabilitation robotics offers a promising approach to enhancing recovery in patients with musculoskeletal or cerebrovascular injuries. This article presents the development and validation of a novel variable stiffness joint (VSJ) that replaces large motors to generate resistive forces, thereby facilitating controlled recovery of muscle tone. For a revolute joint mechanism, we show that a constant output force can be maintained by adjusting stiffness, as demonstrated through simulation studies. Further validation was conducted through prototype experiments with volunteer participants, confirming that spring-length control enables modulation of joint stiffness and maintains a constant force at the link's end regardless of the rotation angle or trajectory. This work highlights an effective actuation method capable of delivering personalized and responsive rehabilitation therapy.
Calderon et al. (Wed,) studied this question.