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Here, we present a robotic leg prosthesis that replicates the key biomechanical functions of the biological knee, ankle, and toe in the sagittal plane while matching the weight, size, and battery life of conventional microprocessor-controlled prostheses. The powered knee joint uses a unique torque-sensitive mechanism combining the benefits of elastic actuators with that of variable transmissions. A single actuator powers the ankle and toe joints through a compliant, underactuated mechanism. Because the biological toe dissipates energy while the biological ankle injects energy into the gait cycle, this underactuated system regenerates substantial mechanical energy and replicates the key biomechanical functions of the ankle\/foot complex during walking. A compact prosthesis frame encloses all mechanical and electrical components for increased robustness and efficiency. Preclinical tests with three individuals with above-knee amputation show that the proposed robotic leg prosthesis allows for common ambulation activities with close to normative kinematics and kinetics. Using an optional passive mode, users can walk on level ground indefinitely without charging the battery, which has not been shown with any other powered or microprocessor-controlled prostheses. A prosthesis with these characteristics has the potential to improve real-world mobility in individuals with above-knee amputation.<\/jats:p>","DOI":"10.1126\/scirobotics.abo3996","type":"journal-article","created":{"date-parts":[[2022,11,23]],"date-time":"2022-11-23T13:58:14Z","timestamp":1669211894000},"source":"Crossref","is-referenced-by-count":130,"title":["A lightweight robotic leg prosthesis replicating the biomechanics of the knee, ankle, and toe joint"],"prefix":"10.1126","volume":"7","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6999-108X","authenticated-orcid":true,"given":"Minh","family":"Tran","sequence":"first","affiliation":[{"name":"Department of Mechanical Engineering and Robotics Center, University of Utah, Salt Lake City, UT, USA."}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5569-9099","authenticated-orcid":true,"given":"Lukas","family":"Gabert","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering and Robotics Center, University of Utah, Salt Lake City, UT, USA."}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8304-1884","authenticated-orcid":true,"given":"Sarah","family":"Hood","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering and Robotics Center, University of Utah, Salt Lake City, UT, USA."}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0957-6412","authenticated-orcid":true,"given":"Tommaso","family":"Lenzi","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering and Robotics Center, University of Utah, Salt Lake City, UT, USA."}]}],"member":"221","reference":[{"key":"e_1_3_3_2_2","doi-asserted-by":"publisher","DOI":"10.1080\/17483100802715092"},{"key":"e_1_3_3_3_2","doi-asserted-by":"publisher","DOI":"10.1177\/0309364617747976"},{"key":"e_1_3_3_4_2","doi-asserted-by":"publisher","DOI":"10.1097\/00003086-199904000-00006"},{"key":"e_1_3_3_5_2","first-page":"119","article-title":"Designs and performance of three new microprocessor-controlled knee joints","volume":"64","author":"Thiele J.","year":"2018","unstructured":"J.\u00a0Thiele, C.\u00a0Sch\u00f6llig, M.\u00a0Bellmann, M.\u00a0Kraft,Designs and performance of three new microprocessor-controlled knee joints. 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