In recent years, there is an increase in the number of people that require support during walking as a result of a decrease in the leg muscle strength accompanying aging. An important index for evaluating walking ability is step length. A key cause for a decrease in step length is the loss of muscle strength in the legs. Many researchers have designed and developed orthoses for walking assistance. In this study, we advanced the design of an orthosis for walking assistance that assists the forward swing of the leg to increase step length. We employed a pneumatic artificial muscle as the actuator so that flexible assistance with low rigidity can be achieved. To evaluate the performance of the system, we measured the effect of assistance quantitatively. In this study, we constructed a prototype of the orthosis and measure EMG and step length on fitting it to a healthy subject so as to determine the effect of assistance, noting the increase in the obtained step length. Although there was an increase in EMG stemming from the need to maintain body balance during the stance phase, we observed that the EMG of the sartorius muscle, which helps swing the leg forward, decreased, and the strength of the semitendinosus muscle, which restrains the leg against over-assistance, did not increase but decreased. Our experiments showed that the assistance force provided by the developed orthosis is not adequate for the intended task, and the development of a mechanism that provides appropriate assistance is required in the future.

As the aged population increases, increasing numbers of people require walking support as the strength of their leg muscles deteriorates. We have developed a flexible power walking assistant system based on pneumatic artificial muscle. To date, the walking assistance effect of this approach has been validated in experiments, but few subjects were recruited. In the present study, we have incorporated pneumatic rubber artificial muscle into a new mechanism, enabling smaller and lighter weight devices for walking assistance. Unlike conventional mechanisms of this type, which require separate artificial muscles for each foot, our proposed mechanism assists both feet by a single artificial muscle. A prototype model of our proposed new mechanism was applied to artificial muscles, and its practicality was evaluated in operational experiments.

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