Abstract
A power-assisted chair is designed to help user motion with a pneumatic cylinder. Force of the cylinder is controlled to be proportional to the seat angle. The control leads to virtual spring characteristics. In this paper, the virtual spring characteristics are modified to make the spring constant variable depending on the seat angle. Another function of the chair, which is added in this paper, is a function of locking the seat at the top position. Combining these control techniques, a control technique called total mode control is proposed.
