RT Journal Article SR Electronic T1 Powered knee and ankle prosthesis with indirect volitional swing control enables level-ground walking and crossing over obstacles JF Science Robotics JO Sci. Robotics FD American Association for the Advancement of Science SP eaba6635 DO 10.1126/scirobotics.aba6635 VO 5 IS 44 A1 Mendez, Joel A1 Hood, Sarah A1 Gunnel, Andy A1 Lenzi, Tommaso YR 2020 UL http://robotics.sciencemag.org/content/5/44/eaba6635.abstract AB Powered prostheses aim to mimic the missing biological limb with controllers that are finely tuned to replicate the nominal gait pattern of non-amputee individuals. Unfortunately, this control approach poses a problem with real-world ambulation, which includes tasks such as crossing over obstacles, where the prosthesis trajectory must be modified to provide adequate foot clearance and ensure timely foot placement. Here, we show an indirect volitional control approach that enables prosthesis users to walk at different speeds while smoothly and continuously crossing over obstacles of different sizes without explicit classification of the environment. At the high level, the proposed controller relies on a heuristic algorithm to continuously change the maximum knee flexion angle and the swing duration in harmony with the user’s residual limb. At the low level, minimum-jerk planning is used to continuously adapt the swing trajectory while maximizing smoothness. Experiments with three individuals with above-knee amputation show that the proposed control approach allows for volitional control of foot clearance, which is necessary to negotiate environmental barriers. Our study suggests that a powered prosthesis controller with intrinsic, volitional adaptability may provide prosthesis users with functionality that is not currently available, facilitating real-world ambulation.