Our ankle-foot prosthesis is simple, lightweight, and highly capable. It can be worn by transtibial amputees using a standard pyramidal adapter, or by non-amputees using our simulator boot and lift shoe combination. The device is suitable for up to 250lb users walking at a brisk pace.

The device provides controllable torque about a single ankle axis. The keel portion of the device is robotically-controlled by the actuator unit, while a passive heel spring provides compliance in early stance. Applied torque is measured with a load cell and joint angle with a high-resolution optical encoder. When paired with our bowden cable actuator unit and a simple torque control loop, force can be modulated at 17Hz.


Weight 0.92 kg
Peak Ankle Torque 207 Nm
Torque Control Bandwidth 17 Hz


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Below is a selection of publications from the Carnegie Mellon Biomechatronics Lab that describe studies that utilized an early version of the tethered robotic ankle prosthesis. 

  • Malcolm, P., Quesada, R. E., Caputo, J. M., Collins, S. H. (2015) The influence of push-off timing in a robotic ankle-foot prosthesis on the energetics and mechanics of walking. Journal of NeuroEngineering and Rehabilitation, 12:21. Link.
  • Quesada, R. E., Caputo J. M., Collins, S.H. (2016) Increasing ankle push-off work with a powered prosthesis does not necessarily reduce metabolic rate for transtibial amputees. Journal of Biomechanics, 49:3452-3459. Link.
  • Caputo, J. M., Collins, S. H. (2014) Prosthetic ankle push-off work reduces metabolic rate but not collision work in non-amputee walking. Nature Scientific Reports, 4:7213. Link.