A composite position control of flexible lower limb exoskeleton based on second-order sliding mode

Aiming at the problem that trajectory tracking error of flexible lower limb exoskeleton robot is too large under condition external disturbance and parameters uncertainty, a composite position control method based on second-order sliding mode was proposed. Firstly, modeled by Lagrange function. Secondly, considering system affected not only matched but also unmatched disturbance, two finite time state observers are used to observe compensate disturbances in real time. The super-twisting employed section ensure knee joint converges zero Finally, Lyapunov function proves stability suggested technique. experimental findings reveal approach has better effect resilience than classic PD control, indicating its superiority.