Study for control of a power assist device. Development of an EMG based controller considering a human model

A power assisting device for lower back flexion and extension, when carrying a heavy load is presented in this paper. When people lift up something heavy, they use both hands. So the development of a controller without using hands is necessary. We attempt to control the device by a voluntary human motion. First, lifting up and putting down motions are analyzed using a human model. Results show that torques in a hip joint and a knee joint are characteristic for control the device. It means that EMG signals in front and back thigh muscles can become feature values because the muscles located there connect the hip joint and the knee joint. After that, a controller of the device using the EMG signals is developed. Finally, artificial neural networks (ANN) are introduced as a solution of the problem of individual differences.