Robust Missile Autopilots With Finite‐Time Convergence

Abstract

This paper presents a new longitudinal autopilot to address the finite-time tracking problem for uncertain agile missiles. The proposed autopilot is essentially a composite control scheme, which is obtained through the finite-time control methodology and the nonlinear disturbance observer (NDOB) approach. The key idea in this scheme is that the NDOB is adopted to estimate the aerodynamic uncertainties and external disturbances in an integrated manner. With the aid of the finite-time bounded function and the Lyapunov function method, the finite-time stability of the closed-loop system is established, which shows that the angle-of-attack response will converge to the external command signal in finite time. Numerical simulation results are presented to demonstrate the superiority of the proposed scheme.

Finite‐Time Consensus Problem for Second‐Order Multi‐Agent Systems Under Switching Topologies

“…5, Fig. 6 displays that the chattering induced in system (4) under (14) has been largely reduced under (15) while there exists chattering near the stable state during the convergence process of Fig. 5.…”

“…For the protocol (14), from the definition of sign function, although the sign function with fractional power used in (14) indicates that sig(⋅) is strictly increasing odd function and the closed-loop system (4) with (14) is continuous with respect to x i and v i , the large gain leads to high frequencies in the control signal in real-world applications. Note that finite-time convergence implies the non-Lipschitz continuous of multi-agent system.…”

“…where the coefficients are 1 = 0.8, 2 = 2 1 ∕( 1 + 1) = 0.8889 and = 2.3. Figs 2 and 3 display the curves of the evolutions of the position and velocity of system (4) under protocol (14) and (15) with the union graph G 1−8 , respectively. It is shown that the agents' positions and velocities can achieve an average consensus in finite time.…”

“…The finite‐time consensus of multi‐agent systems means that the states of all the agents reach an common agreement in finite time by employing an appropriate consensus protocol. It has been widely used in many areas, such as mobile robots , multiple spacecraft systems , tracking control , synchronous control , containment control , formation control , and attitude control .…”

Neural Network Dynamic Surface Backstepping Control for the Speed and Tension System of Reversible Cold Strip Rolling Mill

“…The dynamic surface control method can effectively avoid the “differential explosion” phenomena, and simplify the controller design process by using low‐pass filters to estimate each virtual control command and its first derivative in the backstepping control. Furthermore, for the uncertainty item with relatively small value and change rate, a nonlinear disturbance observer (NDO) can be adopted to conduct dynamic observation and compensation, because its structure is simple, calculation amount is small, and control parameters are easily set. On the other hand, for an uncertainty item with relatively large value and change rate, neural network control , fuzzy control , or fuzzy neural network control can be adopted to conduct dynamic approximation and compensation, because they can approximate any continuous function online, which is helpful to improve the tracking control precision and the robust stability of the system.…”