bottom, thigh, and shank. Hence, the bed has enough degrees of
freedom for achieving sitting, lifting knee, and leg functions. For
precisely performing position control, five dc linear motors are
installed. The posture changing function can be performed by
operating these five dc linear actuators, as shown in Fig. 3. The
reason for using five actuators is to let mechatronic engineers as
well as healthcare personnel test possible caring tasks that can
benefit the bedridden people. In Fig. 3, θ1r is the angle between
the upper body part and the bottom part, θ3r is the angle between
the thigh part and the bottom part, θ4r is the angle between the
shank part the bedplate, and LH is the height of the bottom part.