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  1. Today’s passive prosthetic technologies limit the well-being of millions of individuals with amputations, who often walk slower, use more energy, fall more often, and develop devastating secondary deficits over time. Robotic prostheses hold the promise to address many of these challenges, but safe, reliable control strategies have remained out of reach—that is, a critical gap is the ability to provide appropriate instructions to robotic legs that enable robust ambulation in the real world. Fortunately, there are many researchers studying control strategies, but each group tests their strategies with different robotic hardware in constrained laboratory settings. This mismatch in prosthesis hardware severely limits comparison of control solutions and, along with the lack of testing in real-world environments, hinders the translation of these promising technologies. To address these challenges, we developed the Open Source Leg (OSL): a robotic knee-ankle prosthesis that facilitates controls, biomechanics, and clinical research. This paper describes the design innovations required to develop a bionic leg for broad dissemination, characterization of the OSL’s electromechanical performance, and clinical demonstration with an advanced high-level control strategy, tested with three individuals with above-knee amputations. The OSL provides a common hardware platform for scientific studies and clinical testing, lowers the barrier for new prosthetics research, and enables research beyond the laboratory: in more realistic environments, such as the hospital, community, and home. 
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  2. null (Ed.)
    Recently, brushless motors with especially high torque densities have been developed for applications in autonomous aerial vehicles (i.e. drones), which usually employ exterior rotortype geometries (ER-BLDC motors). These motors are promising for other applications, such as humanoids and wearable robots; however, the emerging companies that produce motors for drone applications do not typically provide adequate technical specifications that would permit their general use across robotics-for example, the specifications are often tested in unrealistic forced convection environments, or are drone-specific, such as thrust efficiency. Furthermore, the high magnetic pole count in many ER-BLDC motors restricts the brushless drives able to efficiently commutate these motors at speeds needed for lightly-geared operation. This paper provides an empirical characterization of a popular ER-BLDC motor and a new brushless drive, which includes efficiencies of the motor across different power regimes, identification of the motor transfer function coefficients, thermal response properties, and closed loop control performance in the time and frequency domains. The intent of this work is to serve as a benchmark and reference for other researchers seeking to utilize these exciting and emerging motor geometries. 
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  3. Challenges associated with current prosthetic technologies limit the quality of life of lower-limb amputees. Passive prostheses lead amputees to walk slower, use more energy, fall more often, and modify their gait patterns to compensate for the prosthesis' lack of net-positive mechanical energy. Robotic prostheses can provide mechanical energy, but may also introduce challenges through controller design. Fortunately, talented researchers are studying how to best control robotic leg prostheses, but the time and resources required to develop prosthetic hardware has limited their potential impact. Even after research is completed, comparison of results is confounded by the use of different, researcher-specific hardware. To address these issues, we have developed the Open-source Leg (OSL): a scalable robotic knee/ankle prosthesis intended to foster investigations of control strategies. This paper introduces the design goals, transmission selection, hardware implementation, and initial control benchmarks for the OSL. The OSL provides a common hardware platform for comparison of control strategies, lowers the barrier to entry for prosthesis research, and enables testing within the lab, community, and at home. 
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  4. Challenges associated with current prosthetic technologies limit the quality of life of lower-limb amputees. Passive prostheses lead amputees to walk slower, use more energy, fall more often, and modify their gait patterns to compensate for the prosthesis’ lack of net-positive mechanical energy. Robotic prostheses can provide mechanical energy, but may also introduce challenges through controller design. Fortunately, talented researchers are studying how to best control robotic leg prostheses, but the time and resources required to develop prosthetic hardware has limited their potential impact. Even after research is completed, comparison of results is confounded by the use of different, researcher-specific hardware. To address these issues, we have developed the Open-source Leg (OSL): a scalable robotic knee/ankle prosthesis intended to foster investigations of control strategies. This paper introduces the design goals, transmission selection, hardware implementation, and initial control benchmarks for the OSL. The OSL provides a common hardware platform for comparison of control strategies, lowers the barrier to entry for prosthesis research, and enables testing within the lab, community, and at home. 
    more » « less