Our ankle prosthesis end-effector 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. We have demonstrated that this device is suitable for steady speed walking for users weighing 250lb.

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.