Nonlinear fractional order proportion-integral-derivative active disturbance rejection control method design for hypersonic vehicle attitude control

• A nonlinear fractional order attitude control method is investigated.
• A nonlinear fractional order PID control technique is introduced.
• The proposed controller consists of a TD, an NFOPIλDμNFOPIλDμ and an ESO.
• The stability and robustness of the proposed method are demonstrated.
• Simulation results are given to show the effectiveness of the proposed controller.

Near space hypersonic vehicle model is nonlinear, multivariable and couples in the reentry process, which are challenging for the controller design. In this paper, a nonlinear fractional order proportion integral derivative (NFOPIλDμNFOPIλDμ) active disturbance rejection control (ADRC) strategy based on a natural selection particle swarm (NSPSO) algorithm is proposed for the hypersonic vehicle flight control. The NFOPIλDμNFOPIλDμ ADRC method consists of a tracking-differentiator (TD), an NFOPIλDμNFOPIλDμ controller and an extended state observer (ESO). The NFOPIλDμNFOPIλDμ controller designed by combining an FOPIλDμFOPIλDμ method and a nonlinear states error feedback control law (NLSEF) is to overcome concussion caused by the NLSEF and conversely compensate the insufficiency for relatively simple and rough signal processing caused by the FOPIλDμFOPIλDμ method. The TD is applied to coordinate the contradiction between rapidity and overshoot. By attributing all uncertain factors to unknown disturbances, the ESO can achieve dynamic feedback compensation for these disturbances and thus reduce their effects. Simulation results show that the NFOPIλDμNFOPIλDμ ADRC method can make the hypersonic vehicle six-degree-of-freedom nonlinear model track desired nominal signals accurately and fast, has good stability, dynamic properties and strong robustness against external environmental disturbances.