Powered prostheses can enable individuals with
above-knee amputations to ascend stairs step-over-step. To accomplish this
task, available stair ascent controllers impose a pre-defined joint impedance
behavior or follow a pre-programmed position trajectory. These control approaches
have proved successful in the laboratory. However, they are not robust to
changes in stair height or cadence, which is essential for real-world
ambulation. Here we present an adaptive stair ascent controller that enables
individuals with above-knee amputations to climb stairs of varying stair
heights at their preferred cadence and with their preferred gait pattern. We
found that modulating the prosthesis knee and ankle position as a function of the
user’s thigh in swing provides toe clearance for varying stair heights. In stance,
modulating the torque-angle relationship as a function of the prosthesis knee
position at foot contact provides sufficient torque assistance for climbing stairs
of different heights. Furthermore, the proposed controller enables individuals
to climb stairs at their preferred cadence and gait pattern, such as
step-by-step, step-over-step, and two-steps. The proposed adaptive stair controller
may improve the robustness of powered prostheses to environmental and human
variance, enabling powered prostheses to more easily move from the lab to the
real-world.
Powered Knee and Ankle Prosthesis with Adaptive Control Enables Climbing Stairs with Different Stair Heights, Cadences, and Gait Patterns
