气动肌肉仿生腿自适应非线性积分滑模控制研究OACHSSCD

Aims:An adaptive nonlinear integral sliding mode control method based on Newton-Raphson-based optimizer(NRBO)was proposed to solve the problem that the pneumatic muscle bionic leg was susceptible to external interference during trajectory tracking.Methods:Firstly,an integral sliding mode surface with nonlinear saturation function was designed to improve the response speed of the system while suppressing the integral saturation phenomenon.Secondly,a variable exponential reaching law was introduced;and its coefficient could be dynamically adjusted according to the state of the sliding surface.It was proved by theoretical calculation that the convergence time of the reaching law was shorter.Then,the adaptive control strategy was used to estimate the upper bound of the total disturbance of the system online to eliminate the influence of external disturbance.Finally,the NRBO algorithm was used to optimize the controller hyperparameters to further improve the control performance.Results:Compared with the integral sliding mode controller,the proposed method reduced the mean absolute error(MAE)and root mean square error(RMSE)of the hip joint by 41.6％and 19.5％,respectively,and the MAE and RMSE of the kneejoint by 24.9％and 4.1％,respectively.Conclusions:The proposed control method effectively improves the trajectory tracking accuracy of the pneumatic muscle bionic leg.