For motor rehabilitation of hemiplegic patients by means of motorized orthoses, as well as in intelligent prosthetics, a major challenge is the coordination of healthy and robotically assisted limbs. The new method of Complementary Limb Motion Estimation (CLME) analyzes depen-dencies among human Degrees of Freedom (DoFs) in healthy subjects. Based on this knowledge, adequate motion for inoperable DoFs in patients is estimated on-line from sound limb motion. Thus, the intention of a partially paralyzed person or an amputee can be deduced from residual body motion, in order to coordina-tely actuate or supervise the impaired limbs. The aim is to increase the dominance of the patient and to reduce the robot to an assistive device. In continuity of priorly published evaluation by comuter simula-tions, this paper presents a first experimental proof of concept of CLME with healthy subjects. The results of these preliminary tests affirm the suitability of the algorithm for cooperative human-robot interaction.

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Electrical motors are reversible machines; they can function as motors or as generators. A motor receives electrical power from a battery and transforms it in torque developing a Counter Electromotive Force CEMF, which opposes the battery. A generator receives mechanical power from a mechanical actuator and transforms it in electrical power developing a Counter Torque, which opposes the actuator. A motor behaves as motor and as generator at the same time. In fact while a motor is ‘motoring’, that is doing mechanical work, it generates CEMF acting as generator, although the CEMF is lower than the battery voltage so the motor acts as a load and absorbs current. In certain situations the CEMF may overcome the battery, in which case the generator component becomes dominant; the motor acts as a generator inverting the direction of its current and forcing it into the battery. The typical situation is the one of a heavy vehicle rolling on a sharp downhill slope and forcing the motor to turn fast enough that the CEMF becomes larger than the battery voltage. As soon as the motor overcomes the battery it inverts the current direction and starts feeding current into the battery, while developing a counter torque that acts as a brake. This phase is called regeneration (recharging of the battery).

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An exoskeleton worn by a human user consisting of a rigid pelvic harness worn about the waist of the user and exoskeleton leg structures each of which extends downwardly alongside one of the human user’s legs. The leg structures include hip, knee and ankle joints connected by adjustable length thigh and shin members. The hip joint that attaches the thigh structure to the pelvic harness includes a passive spring or an active actuator to assist in lifting the exoskeleton and said human user with respect to the ground surface upon which the user is walking and to propel the exoskeleton and human user forward. A controllable damper operatively arresting the movement of the knee joint at controllable times during the walking cycle, and spring located at the ankle and foot member stores and releases energy during walking.

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Gravity balancing is often used in industrial machines to decrease the required actuator efforts during motion. In this paper, we present a new design for gravity balancing of the human leg using an external orthosis. This external orthosis is connected to the human leg on the shank and its other end is fixed to a walking frame. The major issues addressed in this paper are: (i) design for gravity balancing of the human leg and the orthosis, (ii) kinematic compatibility of the human leg and the external orthosis during walking, (iii) comparison of the joint torque trajectories of the human leg with and without external orthosis, and (iv) effects of variation of the link lengths and masses of the human leg on the inertia of the external orthosis. We illustrate feasible 2D and 3D designs of the external orthosis through computer simulations. Fabrication of this design will be the subject of future work.

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This paper describes a powered leg orthosis for gait rehabilitation of patients with walking disabilities. The paper proposes controllers which can apply suitable forces on the leg so that it moves on a desired trajectory. The description of the controllers, simulations and experimental results with the powered orthosis are presented in the paper. Currently, experiments have been performed with a dummy leg in the orthosis. In the coming months, this powered orthosis will be used on healthy subjects and stroke patients.

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