Based on the flowchart in Fig. 12, several bed motions during
the posture changing task can be performed. The snapshot of
several examples performed by the main bed is shown in Fig. 13.
Fig. 13(a)–(d) shows the example of home position, sitting, knee
lifting, and leg lifting, respectively. The sitting task is performed
after finishing the home position task. Then, the thigh part of
the bed is raised up for lifting the knee. The values of the state
variables θ1r ,θ3r , θ4r , and LH can be calculated based on the
acquired data.