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Abstract

We developed a novel control architecture for robotic leg prostheses that adapts online at each step to provide biological accurate function based on the user gait pattern. The user-adaptive control can restore physiological joint energetics and does not require any tuning–the user can don the robotic leg and go. The movement of the prosthesis during swing phase is adapted to the user online using minimum-jerk principle. Minimum-jerk provides an optimal way to program a smooth movement, allowing amputees to obtain physiological gait symmetry at variable cadences, and, potentially, to handle unexpected perturbations such as tripping. This controller was first tested on the Vanderbilt leg–a state of the art powered ankle and knee prosthesis developed by Dr. Michael Goldfarb at Vanderbilt University.

Variable Cadence Contol – Amputee testing

https://youtu.be/kDb_L_zJlDg

Crossing over obstacles – Amputee testing

https://youtu.be/K4EMpooTjmQ

 

Abstract

We designed a robotic system that can transform a conventional passive prosthesis into a powered robotic leg, thus allowing transfemoral amputees to perform activities that would not have been possible with their prescribed passive prostheses, such as climbing stairs. The Robotic Retrofit Prosthesis comprises two main functional elements: (1) a powertrain, which includes the motor and the primary transmission system, and (2) a motorized clutch that engages the motor and the primary transmission system during activities that require positive power such as standing up from a seated position or climbing stairs.

 

Preliminary validation with an able-bodied subject

https://youtu.be/rFSVWvTYHmw

 

Bench-top testing – Motorized clutch

https://youtu.be/utHhHkwHXRA

 

Abstract

We developed a novel hybrid actuation system for robotic knee prosthesis that combines a conventional passive spring/damper system with an innovative variable transmission based on slider-crank design. The Hybrid Knee is as lightweight as a passive device, and as strong as a heavy fully-powered prosthesis, helping subjects to stand up from a sited position and to ambulate on stairs.

 

Preliminary validation with a transfemoral amputee subject

Switching between Active and Passive mode