Clutchable series-elastic actuator: Implications for prosthetic knee design

Abstract

Currently, the mobility of above-knee amputees is limited by the lack of available prostheses that can efficiently replicate biologically accurate movements. In this study, a powered knee prosthesis was designed utilizing a novel mechanism, known as a clutchable series-elastic actuator (CSEA).The CSEA includes a low-power clutch in parallel with an electric motor within a traditional series-elastic actuator. The stiffness of the series elasticity was tuned to match the elastically conservative region of the knee’s torque-angle relationship during the stance phase of locomotion. During this region, the clutch was used to efficiently store energy in the series elasticity. The fully autonomous knee prosthesis design utilized a brushless electric motor, ballscrew transmission and cable drive, as well as commercial electrical components. The knee was lighter than the eighth percentile and shorter than the first percentile male shank segment. The CSEA Knee was tested in a unilateral above-knee amputee walking at 1.3 m/s. During walking, the CSEA Knee provided biomechanically accurate torque-angle behavior, agreeing within 17% of the net work and 27% of the stance flexion angle produced by the biological knee. In addition, the process of locomotion reduced the net electrical energy consumption of the CSEA Knee. The knee’s motor generated 1.8 J/stride, and the net energy consumption was 3.6 J/stride, an order of magnitude less energy than previously published powered knee prostheses.

Adaptive Foot in Lower-Limb Prostheses

“…Therefore energy saving mechanisms have been introduced by prosthesis developers to reduce the power requirement. The spring-based energy storing and regenerating methods like series elastic actuators (SEA) [48], parallel elastic actuators (PEA), clutchable series elastic actuators (CSEA) [49], continuously variable series elastic actuators [50], and so forth are some examples for such mechanisms. Attaching methods of adaptive foot prostheses to lower-limb prostheses are mainly coupling, pyramid type attachments.…”

A Novel Design for Adjustable Stiffness Artificial Tendon for the Ankle Joint of a Bipedal Robot: Modeling & Simulation

“…Designing an actuated joint that can provide high torque while keeping low energy consumption is a great challenge. One of the most successful research achievements in designing such a joint is the design made in [27]. The actuator design of [27] can provide high torque and low energy consumption for the knee joint of a prosthetic leg.…”

“…The actuator design of [27] can provide high torque and low energy consumption for the knee joint of a prosthetic leg. Inspired by the design presented in [27], we proposed a novel design for providing rotational motion for the ankle pitch joint of the WABIAN-2R.…”

Soft wearable assistive robotics: exosuits and supernumerary limbs

“…Literature reports a multitude of devices employing series elastic [2], pneumatic [3] and variable impedance actuators [4] which found their natural application in rehabilitation [5], telemanipulation [6] and in general for all those tasks which can benefit from force limitation and fine regulation of the interaction at the end effector.…”