Incremental Backstepping Sliding-Mode Trajectory Control for Tailless Aircraft with Stability Enhancer

Abstract

This paper presents an incremental backstepping sliding-mode (IBS) controller for trajectory control of a tailless aircraft with unknown disturbances and model uncertainties. The proposed controller is based on a nonlinear dynamic model of the tailless aircraft. A stability enhancer (SE) that limits both the rate and amplitude of the virtual control input is proposed. The stability enhancer consists of two layers. When the virtual control input approaches the edge, the first layer SE would be activated to modify the trajectory tracking error; when the virtual control input exceeds the edge, the second layer SE would reduce the control gains to make sure the virtual control input drops within the edge as soon as possible. With the help of SE, the incremental control method could be extended to outer-loop control without considering the dynamics of the inner-loop system. In addition, an adaptive estimator for state derivatives is proposed, together with IBS, allowing the controller to show excellent robustness. Finally, two simulations are presented. The first simulation shows that the system is insensitive to external disturbances and model uncertainties, and the effectiveness of SE is proved in the second simulation.

A Multiobjective Incremental Control Allocation Strategy for Tailless Aircraft

“…(1) A closed-loop incremental nonlinear control allocation method with the active set quadratic programming solver is presented, which is effective in precisely allocating the virtual control command against the adverse effects caused by nonlinear control effectiveness. What is more, the high precision of the proposed method is theoretically verified by proving its convergence, while other similar references [25][26][27] that introduce nonlinear control allocation methods usually ignore this essential step…”

Attitude-Tracking Control for Over-Actuated Tailless UAVs at Cruise Using Adaptive Dynamic Programming

“…This effectively eliminates the need for MTV, ensuring that effector saturation is avoided. The motion equation of 6-DOF UAV model is given below [14,18,52], the nomenclature of the variables in the following equation can be found in Table 2.…”

“…From Equation ( 14), it could be known that it is difficult to obtain the dynamic of x c 2 because of its dependence on the second order derivative of x d 1 . In many control methods, such as incremental control methods [14], ẋc 1 is readily available, but ẋc 2 is usually obtained through digital differentiation, which is not only sensitive to noise but also increases the computational complexity. Therefore, in ADP, the dynamic of x d 2 is constructed using NDI, and the use of ẍd 1 could be avoided in this way.…”

“…Many researchers have developed different control algorithms for the nonlinear ICE model. In a recent study, He et al [8] proposed an altitude tracker for ICE using the well-known decoupling conditions for nonaffine systems [9][10][11][12][13][14], while other researchers prefer incremental control methods.…”

“…Sun et al [17] improved the CA of ICE using hierarchical multi-objective optimization and adaptive incremental backstepping. Additionally, He et al [14] extended the incremental control to the outer-loop control of ICE trajectory tracking using the pseudo-control hedging technique and relaxing the need for a timescale separation principle.…”