Recently, many developed countries have begun to experience the problems associated with an aging society. One problem in particular is the growing number of older adults in the labor force who suffer from various physical restrictions. Aiming to develop technology to assist these individuals, our laboratory has proposed a wire suspension-type power assist system that amplifies the force applied by the user. This system can be used even by older adults with insufficient strength for controlling the position and the configuration of heavy objects. The power assist system currently being developed in our laboratory uses a load cell to detect simultaneously both the force applied to the object by the user and the weight of the object. Therefore, the weight of the object is limited due to the signal-to-noise ratio (i.e., the ratio of the applied force to the weight of the object). Thus, we propose a new system that estimates the force applied to the object on the basis of the ground reaction force. This paper presents a model of the force applied by a human hand which is based on the ground reaction force. Then, the validity of the model is verified through simulation and experiment. As a result, it is confirmed that the force applied by a user can be estimated from the ground reaction force.

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In recent years, the use of pneumatics in innovative actuation systems has led to the development, testing and first applications of nonconventional actuators such as pneumatic muscles. Like human muscles, pneumatic muscles can exert only traction forces, and offer a good power-to-weight ratio. The paper will present an investigation of new pneumatic muscles with a fabric structure. Lightweight, robust and efficient, these muscles can be used in a wide range of fields, from biomedical to industrial applications.

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Rehabilitation of walking is an essential element in the treatment of incomplete spinal cord injured (SCI) patients. During the early post injury period, patients find it challenging to practice upright walking. Simulating stepping movements in a supine posture may be easier and promote earlier rehabilitation. A robotic orthotic device for early intervention in spinal cord injury that does not require the patient to be in an upright posture has been modelled. The model comprises a two-bar mechanical system that is configured and powered to provide limb kinematics that approximate normal overground walking. The modelling work has been based on gait analysis performed on healthy subjects walking at 50 per cent, 75 per cent, and 100 per cent of normal cadence. Simulated angles of hip, knee, and ankle joints show a comparable range of motion (ROM) to the experimental walking data measured in healthy subjects. The model provides operating parameters for a prospective recumbent gait orthosis that could be used in early walking rehabilitation of incomplete SCI patients.

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A robotic tendon is modeled and the stiffness of the spring is tuned so that the spring power reduces the peak motor power and energy required for ankle gait. When determining stiffness from gait literature, it is usually assumed that one side of the spring is fixed. We assume that the spring is translating to derive a second method to calculate stiffness. By choosing a tuned spring based on a “dynamic stiffness”, the motor velocity was shown to be constant during the loading phase of ankle gait. We simulated this system and showed that energy was reduced and peak power was dramatically reduced. The constant velocity controller was implemented on a powered ankle foot orthosis and test data was correlated with the simulation.

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Mechatronics is at present a dominating concept of designing machines and devices of various kinds. High speeds of data acquisition and processing achieved by means of microprocessor controllers used in such systems, as well as high dynamics of the actuators applied, make it possible to employ mechatronic devices in quite new fields. This refers to the medical domain as well, and wearable robots are one of the most spectacular examples. They are personoriented robots that can be defined as devices worn by human operators, whether to enhance the function of a limb or to replace it completely. The authors work on an orthotic robot for disabled people suffering from paresis of lower limbs. In the paper, there is proposed a functional structure of such device as well as review of similar systems under development around the world.

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