抄録
With a rise in the number of people requiring nursing-care in the aging society, the demand for welfare equipments that maintain the quality of nursing-care is increasing. In particular, electric wheelchairs are effective in improving QOL because they support the voluntary movement of users, but the majority of them needs to be operated by movements of upper limbs. Then, the authors developed an operation system of electric wheelchairs that is controlled by voluntary head movements. However, EMG measurement system malfunctioned in low temperature environments, which made it impossible to operate electric wheelchairs. Thus, it is necessary to clarify the cause of this malfunction and ensure the stability of operation. In this study, first, the operation was tested in comfortable environments and low temperature environments (-2<PMV<-3). Next, operation reliability was evaluated based on task success rate and malfunction rate. Consequently, the task success rate and the malfunction rate in low temperature environments were 79% and 12%, which were similar to the results in comfortable environments. Therefore, this system can maintain operation reliability at -2<PMV<-3. Meanwhile, it is indispensable to verify in harsher low temperature than -2<PMV<-3 environments, due to be suggested that the change in muscle fiber conduction velocity was small.
