INVERSE DYNAMIC ROBUST CONTROL OF SIT-TO-STAND MOVEMENT

Sit-to-stand (STS) motion is one of the most common movements of a person during daily life. The motion, as a prerequisite for other movements, such as running and climbing, can be a very challenging task for the elderly or disabled people. Assistant tools, such as auxiliary walkers and exoskeletons, are commonly used to help these individuals have independent or at least semi-independent life. In order to design efficient rehabilitation treatments and also develop assistive devices for STS motion, it is necessary to have a validated dynamic model with an appropriate embedded controller on the ancillary instrument to reach the desired posture of the human body. In this paper, a linkage-based dynamic model of STS motion using Lagrange's equation is extracted. The dynamic of the model is simulated using anthropometric parameters associated with the subject. Moreover, two robust controller types are designed and implemented in the presence of sinusoidal bounded disturbances in the dynamic system on the model in order to track the desired trajectory acquired from experimental kinematic data. The simulation results of the controlled dynamic model are compared with experimental data from a healthy subject and demonstrate the performance of the controller. The proposed model can be utilized in the design and control of an assistance device for STS motion.