Design and control of a sit-to-stand assistive device based on analysis of kinematics and dynamics

Sit-to-stand is a common activity in daily life. It is difficult for the elderly and patients with lower limb disorders to complete this motion due to limb pain, muscle weakness, partial loss of motor control function, and physical defects in joints. An STS assistive device is a piece of automated medical equipment that can facilitate rehabilitation training for patients with lower limb disorders and improve their lower limb function. In this paper, we introduce a 3-DOF series type STS assistive device. First, we selected 26 healthy adults to carry out an STS transfer experiment, and we obtained the trajectory and velocity of each joint and the law of plantar pressure during STS motion. Second, based on the above kinematics and dynamics law, a 3-DOF series mechanism was designed. Through forward and inverse kinematics analysis, the relationship between the end-effector and the linear actuator was established. The trajectory planning of the end-effector was carried out according to the natural STS transfer trajectory, and the law of the linear actuator was obtained. The trajectory planning was verified by ADAMS. Finally, the Arduino controller was used to build the control system of the STS assistive device, and the prototype experiment was carried out