distance moved by the bar and the angle rotated by the upper
body part can then be found. The schematic design of the upper
body part is shown in Fig. 4.LA1 is the linear actuator,Adenotes
the joint connecting the upper body part and the bottom part,
B denotes the connecting location of the linear actuator and the
bed chassis, and C denotes the connecting location between the
extended axis of linear actuator and the upper body part.