Development of Legless Chair with Seat Motion Which Follows Standing Up Action

Characteristics of Action Force

Abstract

The paper presents characteristics of action and reaction force in the chair drive mechanism. When axis of the rotation link approaches horizontally in the legless chair state, tensile force acting in the drive wire increases rapidly. Therefore, big power actuator is required at early lifting stage. A few solutions were considered to reduce the peak necessary drive force. The first, rigidity of wire is sufficiently increased so that there may be completely no elongation. The second, the peak is canceled by addition of boost effect of gas spring. The third, axis of the rotation link is constrained by landing stopper, before the link is achieved in a horizontal position. The actuator with function of irreversible motion must be used the mechanism, because the pullback force is needed near standing position. The experimental results agree approximately with the theoretical analysis, and then theoretical considerations could be proved for its validity.