A Novel Adaptive Gain Integral Terminal Sliding Mode Control Scheme of a Pneumatic Artificial Muscle System With Time-Delay Estimation

This paper develops a novel adaptive gain integral terminal sliding mode control with time-delay estimation to enhance the control performance of a pneumatic artificial muscle system. The main contribution of the paper is that the proposed control method can enable the benefits of both terminal sliding mode technique and an integral sliding mode approach. Thus, the controlled system not only achieves finite time convergence and robust performance but also attenuates the drawback of the reaching phase in the conventional sliding mode control approach. To develop the control algorithm, the mathematical of the pneumatic artificial muscle system is first design, which includes a nominal system and all uncertainties and disturbances in the system dynamics. Then, a backstepping terminal sliding mode is designed to achieve a finite time convergence of tracking errors in the nominal system. In addition, an integral terminal sliding mode approach is proposed to reject the uncertainties and disturbances. To enhance the control performance, a time-delay estimation is employed to approximate the nonlinearity and disturbance in the system and an adaptive gain scheme is coupled directly to estimate the ideal robust control gain, which can reduce the chattering phenomenon and increase the tracking accuracy. The stability of the controlled system is analyzed using Lyapunov theory. Moreover, the effectiveness of the proposed control algorithm is verified through a series of experimental tests on a developed pneumatic artificial muscle system.