Powered Lower Limb Devices

A robotic knee and ankle prosthesis for transfemoral amputees

Despite significant technological advances over the past decade (such as the introduction of microcomputer-modulated damping during swing), the majority of commercial transfemoral prostheses remain limited to energetically passive devices. That is, the joints of the prostheses can either store or dissipate energy, but cannot provide any net power over a gait cycle. During level walking, transfemoral amputees expend up to 60% more metabolic energy relative to healthy subjects, and exert as much as three times the affected-side hip power and torque relative to healthy subjects.

We have shown preliminary results that suggest a prosthesis with actively powered knee and ankle joints will significantly enhance the mobility of these transfemoral amputees, both by diminishing the biomechanical disparity between transfemoral amputees and healthy persons during level walking, and by enabling forms of locomotion, such as slope and stair climbing, not presently afforded by passive prostheses.

The device seen at the right is our most recent prototype and is an entirely self-contained, powered knee and ankle prosthesis. Its control system allows the user to perform a wide variety of daily activities, including walking at different cadences, standing on unlevel terrain, and ascending or descending both slopes and stairs.

This technology has been licensed to Freedom Innovations, who plans to continue the development of this prosthesis and bring a version to the commercial market soon.

prosthetic leg

Media

Science Nation: Bionic Leg Makes Amputee Faster on his Feet

Science Nation is a science video series commissioned by the NSF Office of Legislative and Public Affairs. This video features one of our subjects as he helps test the Generation 2 prototype.

Preliminary Stumble Reactions

Through the use of inertial measurement sensors, we have been able to detect a stumble in gait within 100ms of its occurence. This video demonstrates 4 conditions in which the Generation 1 prosthesis is able to detect and appropriately react to a stumbling event.

Activities of Daily Living

This video demonstrates some of the functionality in the Generation 1 prosthesis. A transfemoral test subject navigates level and sloped terrain on Vanderbilt's campus, demonstrating sit-to-stand, stand-to-sit transitions, variable cadence walking, and slope ascent and descent.

Slope Ascent Comparison

This video highlights the benefits of a powered knee and ankle for the purpose of slope ascent. A transfemoral test subject walks on 5 and 10 degree slopes with the Generation 1 powered prosthesis, and also with his daily use prosthesis (an MPC knee and carbon-fiber ankle-foot complex).

Publications

  • Standing Stability Enhancement with an Intelligent Powered Transfemoral Prosthesis, B. Lawson, H. A. Varol, and M. Goldfarb, IEEE Transactions on Biomedical Engineering, vol. 58, iss. 9, pp. 2617-2624, 2011.

  • Upslope Walking with a Powered Knee and Ankle Prosthesis: Initial Results with an Amputee Subject, F. Sup, H. A. Varol, and M. Goldfarb, IEEE/ASME Transactions on Neural Systems and Rehabilitation Engineering, vol. 19, iss. 1, pp. 71-78, 2011 .

  • Volitional Control of a Prosthetic Knee Using Surface Electromyography, K. Ha, H. A. Varol, and M. Goldfarb, IEEE Transactions on Biomedical Engineering, vol.58, iss. 1, pp. 144-151, 2011.

  • Ground Adaptive Standing Controller for a Powered Transfemoral Prosthesis, B. Lawson, H. A. Varol, and M. Goldfarb, IEEE International Conference on Rehabilitation Robotics, 2011.

  • Myoelectric Control of a Powered Knee Prosthesis for Volitional Movement During Non-Weight-Bearing Activities, K. Ha, H. A. Varol, and M. Goldfarb, IEEE International Conference of Engineering in Medicine and Biology Society, 2010.

  • Stumble Detection and Classification for an Intelligent Transfemoral Prosthesis, B. Lawson, H. A. Varol, F. Sup, and M. Goldfarb, IEEE International Conference of Engineering in Medicine and Biology Society, 2010.

  • Multiclass Real-Time Intent Recognition of a Powered Lower Limb Prosthesis, H. A. Varol, F.Sup, M. Goldfarb, IEEE Transactions on Biomedical Engineering, vol. 57, iss. 3, pp. 542-551, 2010.

  • Preliminary Evaulations of a Self-Contained Anthropomorphic Transfemoral Prosthesis, F. Sup, H. A. Varol, J. Mitchell, T. J. Withrow, M. Goldfarb, IEEE/ASME Transactions on Mechatronics, vol. 14, iss. 6, pp. 667-676, 2009.

  • Self-Contained Powered Knee and Ankle Prosthesis: Initial Evaluation on a Transfemoral Amputee, F. Sup, H. A. Varol, and M. Goldfarb, IEEE International Conference on Rehabilitation Robotics, pp. 638-644, April 2009.

  • Powered Sit-to-Stand and Assistive Stand-to-Sit Framework for a Powered Transfemoral Prosthesis, H. A. Varol, F.Sup, and M. Goldfarb, IEEE International Conference on Rehabilitation Robotics, pp. 645-651, April 2009.

  • Real-time Gait Mode Intent Recognition of a Powered Knee and Ankle Prosthesis for Standing and Walking, H. A. Varol, F. Sup, and M. Goldfarb, IEEE RAS and EMBS International Conference on Biomedical Robotics and Biomechatronics, 2008.

  • Design and Control of a Powered Transfemoral Prosthesis, F. Sup, A. Bohara, and M. Goldfarb, International Journal of Robotics Research, vol. 27, no. 2, pp. 263-273, 2008.

  • Decomposition-Based Control for a Powered Knee and Ankle Transfemoral Prosthesis, H.A. Varol, and M. Goldfarb, IEEE International Conference on Rehabilitation Robotics, 2007.

  • Real-time Intent Recognition for a Powered Knee and Ankle Transfemoral Prosthesis, H.A. Varol, and M. Goldfarb, IEEE International Conference on Rehabilitation Robotics, 2007.

  • Design and Control of an Electrically Powered Knee Prosthesis, K. Fite, J. Mitchell, F. Sup, and M. Goldfarb, IEEE International Conference on Rehabilitation Robotics, 2007.

  • Design and Control of a Powered Knee and Ankle Prosthesis, F. Sup, A. Bohara, and M. Goldfarb, IEEE International Conference on Robotics and Automation, 2007.

  • Design of a Pneumatically Actuated Transfemoral Prosthesis, F. Sup, and M. Goldfarb, Proceedings of ASME International Mechanical Engineering Conference and Exposition, 2006.