It has been shown previously that for slow to normal walking speeds the ankle joint behaves similar to a passive mechanism from foot flat to push off. Thus a passive ankle mechanism was developed in order to mimic able-bodied gait in amputees. The ankle device is shown to be capable of matching the ground slope during heel strike, efficiently storing breaking energy from the user during rollover then releasing that energy to assist in push off, and raising the toe during swing phase to reset the system for the next heel strike. Mechanism functionality was verified through lab testing. Human testing was done through an ankle-bypass system on able-bodied subjects to verify device safety and functionality.

A method for decoupling joint stiffness and joint position for simple mechanisms was developed. This method was then demonstrated on a powered ankle prosthesis. Linear and circular mechanisms were fit to the resulting data to simplify the required actuator output. The resulting performance of desired ankle moment with corresponding ankle angle was shown to be highly correlated with able bodied walking data.

Background: Current prosthetic ankle joints are designed either for walking or for running. In order to mimic the capabilities of an able-bodied, a powered prosthetic ankle for walking and running was designed. A powered system has the potential to reduce the limitations in range of motion and positive work output of passive walking and running feet.Methods: To perform the experiments a controller capable of transitions between standing, walking, and running with speed adaptations was developed. In the first case study the system was mounted on an ankle bypass in parallel with the foot of a non-amputee subject. By this method the functionality of hardware and controller was proven.Results: The Walk-Run ankle was capable of mimicking desired torque and angle trajectories in walking and running up to 2.6 m/s. At 4 m/s running, ankle angle could be matched while ankle torque could not. Limited ankle output power resulting from a suboptimal spring stiffness value was identified as a main reason.Conclusions: Further studies have to show to what extent the findings can be transferred to amputees.

A Joint Torque Augmentation Robot (JTAR) was developed to aid walking in an unconstrained outdoor environment. JTAR is a unidirectional, compliant actuator based wearable robot that is designed to power an ankle joint. Since the robot is used to navigate uneven terrain, nearly full ankle range of motion is required to accomplish this goal. The device powers the forward locomotion while permitting out of plane kinematic motion to occur. Metabolic savings of 9% to 20% have been observed while using the JTAR device, when compared to an unpowered/uncoupled state.

A series of Joint Torque Augmentation Robot (JTAR) devices were created to assist the hip joint in walking. Both passive and active assistance approaches were developed. The active device has been demonstrated in an unconstrained outdoor environment.