RESNA 28th Annual Conference - Atlanta, Georgia
Figure 4 shows all forces and torques determined with changing the chair configuration. The x axis is non-dimensional time and the y axis is force or torque. The line types represent different chair configuration. The footrest and seatback angles are 15° and 80° for the solid line, 45° and 80° for the dot line, and 15° and 90° for the dash-dot line. These figures show that all the forces and torques are changed with both the footrest and seatback angles. The change of footrest angle significantly alters the normal and tangential foot forces and the knee torque. The change of seatback angle influences the normal foot force, the seatback force and the knee torque. In general, the normal force at the footrest is a dominant driving force for the extensor thrust. The normal force at the seatback is relatively more significant than that at the seat bottom.