Abstract
BackgroundCurrent 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.MethodsTo 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.ResultsThe 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.ConclusionsFurther studies have to show to what extent the findings can be transferred to amputees.
Highlights
Current prosthetic ankle joints are designed either for walking or for running
Gait quality Walking 1.6 m/s The ankle angle sensor output and the calculated torque of the Walk-Run ankle were compared to healthy subject data
Power curves and related energy of the model calculations [0.17 J/(kg m)] differ to some extent from the values measured by the Walk-Run ankle [0.14 J/(kg m)]
Summary
In order to mimic the capabilities of an able-bodied, a powered prosthetic ankle for walking and running was designed. 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. In contrast to the stiff SACH feet, ESAR feet are able to store energy during the stance phase and release it later during push-off [1, 2]. Through this they are able to mimic the function of the Achilles tendon [3]. In order to support amputees in common daily life activities like walking on flat terrain [10], stairs [12] or slopes [13], Grimmer et al BioMed Eng OnLine 2016, 15(Suppl 3):141 these activities were investigated and biomechanical characteristics were implemented in the active ankle joints
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