Comparison of linear and nonlinear active disturbance rejection control method for hypersonic vehicle

Abstract

Near space hypersonic vehicles have features of strong coupling, nonlinearity and acute changes in aerodynamic parameters, which are challenging for the controller design. Active disturbance rejection control (ADRC) method does not depend on the accurate system model and has strong robustness against disturbances. This paper discusses the differences between the fractional-order PID (FOPIλDμ) ADRC method and the FOPIλDμ LADRC method for hypersonic vehicles. The FOPIλDμ ADRC controller in this paper consists of a tracking-differentiator (TD), a FOPIλDμ controller and an extended state observer (ESO).The FOPIλDμ LADRC controller consists of the same TD and FOPIλDμ controller with the FOPIλDμ ADRC controller and a linear extended state observer (LESO) instead of ESO. The stability of LESO and the FOPIλDμ LADRC method is detailed analyzed. Simulation results show that the FOPIλDμ ADRC method can make the hypersonic vehicle nonlinear model track desired nominal signals faster and has stronger robustness against external environmental disturbances than the FOPIλDμ LADRC method.