The study was never completed as planned.

The goal of this research is to determine a quick, accurate and unobtrusive way to optimize the performance of powered assistive devices like ankle exoskeleton or prostheses.

Lower limb assistive robotic devices, such as active prosthesis, orthoses, and exoskeletons have the potential to restore function for the millions of Americans who experience mobility challenges due to injury and disability. Since individuals with mobility challenges have an increased metabolic costs of transport, the benefit of such assistive devices is commonly assessed via the reduction in the metabolic work rate of the individual who is using the device. Currently, metabolic work rate can only be obtained in a laboratory environment, using breath-by-breath measurements of respiratory gas analysis. To obtain a single steady state data point of metabolic work rate, multiple minutes of data must be collected, since the signals are noisy and slow. In addition, the user has to wear a mask and bulky equipment. The investigators propose an improved way to obtain such estimates of metabolic work rate in real-time. In this project, the investigators will use various small sensors to optimize push-off timing for an active ankle prosthesis.

Inclusion Criteria:

• Has a unilateral amputation
• Has used a prosthesis for at least 6 months

Exclusion Criteria:

• History of orthopedic or neurologic disorders to their intact limb
• History of cardiovascular disease
• Unable to walk for 30 minutes at a time