Abstract: A control method for an upper limb flexible exoskeleton system based on adaptive integral global sliding mode and extended state observer was proposed to address the problem of difficulty in high-precision trajectory tracking caused by external disturbance and parameter uncertainty in the upper limb flexible exoskeleton system. Firstly,the upper limb flexible exoskeleton system was modeled by Lagrangian function,and the model was decomposed into two subsystems for cascade control. Secondly,two extended state observers were used to compensate the parameter uncertainty and external disturbances. In the position trajectory control,an adaptive integral global sliding mode control was constructed,in which a nonlinear integral function was designed to avoid integral saturation. At the same time,an attenuation function was established to accelerate the convergence speed of the global sliding mode surface.The reaching law coefficient may be adaptive adjusted using adaptive control method to reduce chattering and to improve the dynamic performance of the system. Finally,the stability was proved by designed Lyapunov function. The experimental results show that compared with traditional linear active disturbance rejection control and integral sliding mode control,the proposed method has a more accurate trajectory tracking effect and stronger robustness, the control accuracy is improved,and high-precision trajectory tracking is still maintained under external disturbances and system parameter uncertainties,indicating the effectiveness of this control strategy.

Key words: upper limb flexible exoskeleton, adaptive control, integral global sliding mode control, extended state observer