An Ankle-Foot Prosthesis Emulator with Control of Plantarflexion and Inversion-Eversion Torques
نویسندگان
چکیده
Ankle inversion-eversion compliance is an important feature of conventional prosthetic feet, and control of inversion, or roll, in robotic devices could improve balance for people with amputation. We designed a tethered ankle-foot prosthesis with two independently-actuated toes that are coordinated to provide plantarflexion and inversion-eversion torques. This configuration allows elegant, lightweight structures, with a total mass of 0.72 kg. Strain gages on the toes measure torque with less than 2.7% RMS error, while compliance in the Bowden cable tether provides series elasticity. In benchtop tests, the 90% rise time was less than 33 ms and peak torques were 180 N·m in plantarflexion and ±30 N·m in inversion-eversion. The phase-limited closedloop torque bandwidth was 20 Hz with a 90 N·m amplitude chirp in plantarflexion, and 24 Hz with a 20 N·m amplitude chirp in inversion-eversion. The system had low sensitivity to toe position disturbances at frequencies up to 18 Hz. Five values of constant inversion-eversion torque were applied during walking trials, in which RMS torque tracking errors were less than 3.7% in plantarflexion and less than 5.9% in inversion eversion. This platform is therefore suitable for haptic rendering of virtual devices in experiments with humans, which may reveal strategies for improving balance or allow controlled comparisons of conventional prosthesis features. A similar morphology may be effective for autonomous devices.
منابع مشابه
System for powered ankle-foot prosthesis with active control of dorsiflexion-plantarflexion and inversion-eversion
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