This paper presents a bioelectrochemical model for the activation of action potentials on sarcolemma and variation of Ca2+ concentration in sarcomeres of skeletal muscle fibers. The control mechanism of muscle contraction generated by collective motion of molecular motors is elucidated from the perspective of variable-frequency regulation, and action potential with variable frequency is proposed as the control signal to directly regulate Ca2+ concentration and indirectly control isometric tension. Furthermore, the transfer function between stimulation frequency and Ca2+ concentration is deduced, and the frequency domain properties of muscle contraction are analyzed. Moreover the conception of “electro-muscular time constant” is defined to denote the minimum delay time from electric stimulation to muscle contraction. Finally, the experimental research aiming at the relation between tension and stimulation frequency of action potential is implemented to verify the proposed variable-frequency control mechanism, whose effectiveness is proved by good consistence between experimental and theoretical results.

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Social Robotics is an interdisciplinary playground where researchers from sociology, psychology, neuroscience, and robotics meet to design one kind of future robot: the social robot. This challenge is simple to describe, but complex to achieve. The social robot can be a classical robot or a machine with sufficient resources and capabilities to receive and exchange information with humans, with the ultimate result of helping people in daily-life activities. Exchanges should be intuitive and easy: these two key characteristics strongly define the sociability of artificial agents.

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Major limb trauma sustained in combat results in significant long-term disability.1 Opportunity exists to integrate the experience accumulated by hundreds of military orthopaedic surgeons during a decade of conflict in Iraq and Afghanistan with the scientific knowledge held by industry in order to reduce the burden of the often devastating spinal and extremity injuries sustained by the warfighter. Collaboration between healthcare providers who manage explosive high-energy injuries and agencies such as the Defense Advanced Research Projects Agency could prove to be beneficial in protecting persons who are exposed to such injuries.

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Loss of physical mobility makes maximal participation in desired activities more difficult and in the worst case fully prevents participation. This paper surveys recent work in assistive technology to improve mobility for persons with a disability, drawing on examples observed during a tour of academic and industrial research sites in Europe. The underlying theme of this recent work is a more seamless integration of the capabilities of the user and the assistive technology. This improved integration spans diverse technologies, including powered wheelchairs, prosthetic limbs, functional electrical stimulation, and wearable exoskeletons. Improved integration is being accomplished in three ways: 1) improving the assistive technology mechanics; 2) improving the user-technology physical interface; and 3) sharing of control between the user and the technology. We provide an overview of these improvements in user-technology integration and discuss whether such improvements have the potential to be transformative for people with mobility impairments.

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Reduced motor functionality of the upper extremities is one of the most common impairments resulting from spinal cord injuries, occupational and sports injuries, strokes, and other diseases. Partial or even full sensorimotor recovery can be attained through intense and repetitive exercises. In recent years robotic assisted rehabilitation has been shown to improve treatment outcomes in these cases.

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