The proposed study aims to characterize biological ankle joint function during walking and running on slopes in order to further develop advanced powered ankle-foot prostheses. Ankle joint torque and angle data will be collected from non-amputees while walking and running at multiple speeds and slopes. This data will be used to develop control parameters for a powered ankle-foot prosthesis. Then, these parameters will be implemented and tested in a powered prosthesis worn by people with below the knee amputations.

Inclusion Criteria:

Study 1:

- Between 18-60 years old.

Study 2 and 3:

• Between 18-60 years old.
• At least 1 year post-amputation
• no current problems with prosthesis or residual limb
• At least a K3 level of ambulation

Study 4:

- Between 18-45 years old

Study 5:

• Between 18-45 years old
• At least 1 year post-amputation
• no current problems with prosthesis or residual limb
• Experience running with a passive prosthesis
• At least a K4 level of ambulation

Exclusion Criteria:

Studies 1-5

• Cardiovascular, pulmonary, or neurological disease or disorder
• Musculoskeletal injury

Study 1: Non-amputee Study 2: Unilateral transtibial amputee Study 3: Unilateral transtibial amputee Study 4: Non-amputee Study 5: Unilateral transtibial amputee