Controlling Locomotion Over Continuously Varying Activities for Agile Powered Prosthetic Legs

Inclusion criteria for able-bodied participants will be: * Aged between 18 to 65 years Exclusion criteria for able-bodied, young adult participants will be: * Pregnant (self-report) * Any significant neuromuscular or musculoskeletal disorder that would interfere with the study * Unable to walk for 20 minutes * History of any cardiovascular, vestibular, or visual diseases and/or impairments that may interfere with the study * Cognitive deficits that would impair their ability to give informed consent or impair their ability to follow simple instructions during the experiments. In the case of screening for cognitive deficits, the consenting researcher will ask the subject if he/she has any prior history of cognitive deficits. * Adults with a known allergy to medical grade tape Inclusion criteria for subjects with amputation will be: * Aged between 18 to 70 years. * Weigh less than 250 lbs due to limitations in the design of the prosthesis. * Amputee subjects will be more than two months post independent ambulation with an amputation at the transfemoral level in order to use the above-knee prosthesis. * Amputee subjects will have a mobility classification of K2/K3/K4 ambulators (minimum community ambulatory) and have the ability to ambulate without an assistive device beyond their prosthesis. Exclusion criteria for subjects with amputation will be: * Weigh over 250 pounds body * Pregnant (self-report) * Any significant neuromuscular or musculoskeletal disorder that would interfere with the study * Inactive or physically unfit, unable to walk for 20 minutes * An excessively long residual limb length, and/or a non-removable cosmetic cover determined by the prosthetist performing the evaluations * Cognitive deficits or visual impairment that would impair their ability to give informed consent or impair their ability to follow simple instructions during the experiments. In the case of screening for cognitive deficits, the consenting researcher will ask the subject if he/she has any prior history of cognitive deficits. * Co-morbidity that interferes with the study (e.g., pace maker placement, severe ischemia, cardiac disease, etc.) * Adults unable to consent * Adults with a known allergy to medical grade tape