Enhancing robustness of adaptive PID controller of stratospheric balloon-borne gondola attitude control system

The attitude control system of a stratospheric balloon-borne gondola is a typical non-matching uncertain nonlinear system, whose performance can be enhanced to some extent by using an adaptive PID controller. But there is a lack of its stability analysis, which causes some difficulty in selecting its parameters and implementing its algorithm in case of multiple uncertain parameters. So we design a multi-sliding mode controller to help determine the parameters of the adaptive PID controller, reduce its complexity in case of multiple uncertainty parameters and enhance the robustness of nonlinearity, time-varying, vibration and outer disturbance. We use the error threshold value to ensure the robustness of the ideal approximation error of the neural network and avoid the increase of virtual and actual control of various orders, thus stabilizing the adaptive PID controller in its complex states. The computer simulation results, given in Figs. 3 through 6, and their analysis show preliminarily that the adaptive PID controller we designed has a better control accuracy and robustness to nonlinearity, parameters' time-varying, uncertainty and disturbance than traditional adaptive PID controllers.