Design of Assisting Sitting to Standing and Lower Limb Walking Device

To assist patients whose lower limb motor dysfunction to do long distance movement and perform lower limb movements including walking and transform from sitting posture to standing posture (STS), we designed a motion assist device that combines lower limb exoskeleton, STS auxiliary mechanism and wheelchair. According to human anatomy and gait analysis, we determined that the degree of freedom of the exoskeleton is 10, with 3 hip joints, 2 knee joints and 2 ankle joints on each leg. We designed a knee joint based on a cam mechanism and a hip joint based on remote center of motion (RCM) consisting of a parallelogram mechanism and to make the exoskeleton fit with the degree of freedom (DOF) of human motion. To avoid motion interference between the wheelchair and exoskeleton, we establish a kinematic model to calculate the workspace exoskeleton. According to the normal motion path of STS, we designed an assisting STS mechanism based on multi-linear actuator to cooperate with the patient to stand up. We developed an embedded control system to control the entire system for walking assistance and STS assistance. The simulation experiments of walking and STS show that the system conforms to the movement trend of human motion in the process of walking and STS assistance, which verifies the rationality of the design.