Disturbance-observer-based fixed-time second-order sliding mode control of an air-breathing hypersonic vehicle with actuator faults

Abstract

This paper presents a disturbance-observer-based fixed-time second-order sliding mode approach for fault-tolerant control of an air-breathing hypersonic vehicle, where both partial loss of effectiveness faults and bias faults in actuators are considered. Firstly, a fixed-time second-order sliding mode control law is designed to guarantee the reaching time, independent of initial conditions. Then, by using a robust uniformly convergent differentiator technique, a fixed-time convergent disturbance observer is established to quickly estimate the lumped uncertainty, which consists of actuator faults and system uncertainties. Therefore, any information of actuator faults is not required by this design. Finally, simulation results of a generic air-breathing hypersonic vehicle are presented to demonstrate the effectiveness of the proposed controller.

Vector-Coupled Flight Controller Design Based on Multivariable Backstepping Sliding Mode

“…Theorem 1. Considering the control-oriented model of Equation 5, then multivariable backstepping sliding mode controller, Equations (14)- (16), can make the velocity-vector tracking error of Equation (17) be semi-globally uniformly ultimately bounded:…”

“…However, the effective and robust nonlinear control methods that do not require all nonlinearities to be accurate have been used in flight control. Sliding mode control [13][14][15], disturbance observer-enhanced control [16,17], model predictive control [18], adaptive backstepping [19], and dynamic surface control [20] are some nonlinearities that have been considered.…”

“…Cross-coupling that is inherent to flight dynamics. In previous studies [13,14,[16][17][18][19][20][21], the models used to design flight control were decoupled into a scalar form, i.e., state equations with velocity, AOA, sideslip angle, roll rate, pitch rate, and yaw rate, and multiple single-channel controllers were designed. During the decoupling process, some coupling components terms are first calculated/estimated and then compensated for, while the other coupling terms may be disregarded owing to their negligible influence.…”

“…The disturbance observers enhance the scheme of construction of the control law by combining the backstepping sliding mode control feedback with disturbance estimation, based on straightforward and feedforward compensation. Unlike similar works [12,[16][17][18][19], the developed controller not only avoids solving complex matrix equations and treating inverse matrixes, but also fully realizes vector-coupled control. 3.…”

Constrained Adaptive Neural Control for Air-Breathing Hypersonic Vehicles without Backstepping

“…The design of the flight control system is an important issue to ensure that the AHV can accomplish its intended task. Due to the complex flight environment, the highly nonlinear dynamic behavior, and the large uncertainty [3,4], it is a huge challenge to design the controllers with satisfactory performance.…”