A hybrid control method of sliding mode and PID controllers based on adaptive controlled switching portion

Sliding Mode Controller (SMC) can achieve good tracking performance and robustness to the disturbances, but SMC has worse stability and reliability than PID controller. As a most widely used controller, PID controller has many obvious advantages, but it has poorer tracking performance than SMC. In this paper, a hybrid control method of sliding mode and PID controllers is proposed to fully combine the advantages of the two controllers. The SMC uses the exponential reaching rate and integral type switching part to get good tracking performance and avoid chatter effect. The paper also proofs the hybrid control system is stable. In order to improve the system performance, the paper proposes to use adaptive controller to tune the gain coefficient of the switching portion. This is very effective when the system is in the stable state, which will fully decrease the effect of switching portion and use PID controllers to avoid output errors. In order to analyze the performance of the proposed hybrid control method, a simulation example is made. The results show that the hybrid controller can achieve the similar tracking performance and robustness as SMC controller, but higher than PID controller. The results also show that PID controller in hybrid controller can improve stable accuracy of control system.