Spinal cord injury (SCI) affects over 1000 people a year in the UK and has severe consequences for their independence and quality of life. Treatments to address SCI focus on techniques that aim to restore some degree of walking or locomotor activity. One such technique is treadmill training of SCI patients. This paper reviews the use of treadmill training in the recovery of locomotor ability in patients with SCI. Outcomes from treadmill training are variable; for patients with incomplete SCI (where some degree of connection between the brain and the spinal cord is spared from injury), treadmill training only enabled limited full weight-bearing locomotion. In patients suffering a complete SCI (where communication between the brain and spinal cord is lost), no weight-bearing locomotion at all was achieved with training. However, treadmill training does influence the activity of the leg muscles in the acute patients, observed by recordings made from the muscles (electromyography). The impro-vements achieved by treadmill training are not significantly different from other techniques such as over-ground training and functional electrical stimulation. The most effective way of restoring locomotion is through complete repair; however, regeneration techniques are still being developed. For regeneration to take place, the neurons within the spinal cord that are important in generating rhythmic movements (the central pattern generator (CPG) circuits) still need to be functioning, as these circuits have been shown to decline through long periods of inactivation. Treadmill training has therefore an important role in keeping neurons active until regenerative techniques become viable. Furthermore, in spinalized rats, it has been shown that by combining treadmill training with pharmaceutical and electrical stimulation therapies, greater improvements are seen. This suggests that the treatment of spinal cord injury should not be limited to one method. Techniques that repair the damage are the ultimate goal and it is important that patients keep active in order to increase chances of recovery.

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Many of the current implementations of exoskeletons for the lower extremities are conceived to either augment the user’s load-carrying capabilities or reduce muscle activation during walking. Comparatively little research has been conducted on enabling an exoskeleton to increase the agility of lower-limb movements. One obstacle in this regard is the inertia of the exoskeleton’s mechanism, which tends to reduce the natural frequency of the human limbs. A control method is presented that produces an approximate compensation of the inertia of an exoskeleton’s mechanism. The controller was tested on a statically mounted, single-degree-of-freedom (DOF) exoskeleton that assists knee flexion and extension. Test subjects performed multiple series of leg-swing movements in the context of a computer-based, sprint-like task. A large initial acceleration of the leg was needed for the subjects to track a virtual target on a computer screen. The uncompensated inertia of the exoskeleton mechanism slowed down the transient response of the subjects’ limb, in comparison with trials performed without the exoskeleton. The subsequent use of emulated inertia compensation on the exoskeleton allowed the subjects to improve their transient response for the same task.

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An upper limb exoskeleton is a wearable robotic system that is physically linked to the arm of the human operators and its seven actuated degrees of freedom (DOF) match the seven DOF of the human arm. The stability of such a system is critical given the proximity of its human operator. A new PID controller is developed which guarantee asymptotic stability for this class of robotic manipulators. A simulation was used to assess the system performance given the theoretical results of the controller’s parameters with a unique exoskeleton system (EXO-UL7). The simulation also verify the semi-global asymptotic stability of the system. The proposed methodology eliminates the need of the system’s dynamics model for the purpose of designing the controller. It provides an analytical tool for the controller design that is traditionally preformed experimentally (parameter tuning).

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This paper introduces an approach to performance animation that employs a small number of motion sensors to create an easy-to-use system for an interactive control of a full-body human character. Our key idea is to construct a series of online local dynamic models from a prerecorded motion database and utilize them to construct full-body human motion in a maximum a posteriori framework (MAP). We have demonstrated the effectiveness of our system by controlling a variety of human actions, such as boxing, golf swinging, and table tennis, in real time. Given an appropriate motion capture database, the results are comparable in quality to those obtained from a commercial motion capture system with a full set of motion sensors (e.g., XSens [2009]); however, our performance animation system is far less intrusive and expensive because it requires a small of motion sensors for full body control. We have also evaluated the performance of our system by leave-one-out-experiments and by comparing with two baseline algorithms.

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The resistance compensation, especially the friction compensation in the Bowden cable transmission is a difficult issue to be handled. Aimed to the resistance reduction requirement in the active rehabilitative motion, a resistance compensation control method is proposed. Based on the simplified transmission model, the resistance, including the cable friction as well as the mechanical moment of inertial, is formulated. To realize the compensation, force sensors are used to measure the force exerted by the human fingertip. With the proposed algorithm, the maximum finger-exerted force is reduced to less than one third of before. The experimental result demonstrates the validity of the proposed method.

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