Agile Missile Autopilot Design using Nonlinear Backstepping Control with Time-Delay Adaptation

Abstract

This paper deals with a nonlinear adaptive autopilot design for agile missile systems. During the agile turn, there exist highly nonlinear, rapidly changing dynamics and aerodynamic uncertainties. To handle these difficulties, we propose a longitudinal autopilot for angle-of-attack tracking based on backstepping control methodology in conjunction with the time-delay adaptation scheme. The performance of the proposed method is investigated through nonlinear 6-DOF simulations using a reference angle-of-attack profile of agile turn that is obtained from trajectory optimization. An intercept scenario is performed to explore the applicability of the proposed control methodology to agile missile systems.

High angle of attack command generation technique and tracking control for agile missiles

“…Moreover, suitable command structures of the agile missile autopilot are required in order to attain high overall performance [10]. From launching to target acquisition during the agile turn, a practical and effective guidance command should be employed to make the missile correct large leading angle error in velocity.…”

“…A lot of studies mentioned above have designed angle of attack control system, implying a transformation from desired acceleration command to equivalent angle of attack command. To this end, the relationship between missile turn rate and angle of attack was discussed in [6,11] Similarly, under the assumption that the missile body acceleration is proportional to angle of attack, a PI controller approach has been proposed in [10,12] in order to generate a desired angle of attack signal used for tracking body acceleration reference in agile turn. No matter which generation approach of angle of attack command is taken, high angle of attack flight is necessary for a missile to complete the agile turn.…”

Robust Missile Autopilots With Finite‐Time Convergence

“…In [22], the authors used DOB to estimate the coupling terms and external disturbances for bank-to-turn missiles. Using time-delay estimations, a composite backstepping autopilot for agile missiles was proposed in [23]. These references, however, only concerned asymptotical stability, which means that the tracking error converges to zero as time approaches infinity.…”

Practical Solution to Efficient Flight Path Control for Hypersonic Vehicles

“…In this process, an approximate differentiator can be realized by an integrator that can eliminate direct numerical differentiation, which is quite sensitive to measurement noises, as used in another model-free controller: time delay control (TDC). 16,17) Another advantage of ADRC is that it does not require that all the states of a system be available for feedback, which is the foundation of the uncertainty and disturbance estimator (UDE) 18,19) that is a developed version of TDC. Moreover, ADRC has already demonstrated its effectiveness in many fields.…”