Missile Autopilot Research Articles

A Multimode Controller Design for a TBM Autopilot with Optimal/Classical Approach

This paper introduces design of a multimode controller for a Tactical Ballistic Missile autopilot that combined optimal control method with classical frequency domain analysis. In the paper, optimal control method is used to system structure design and to determine gain coefficient, frequency constraints in classical control theory are used to limit the weighting coefficient matrix of objective function in order to ensure system robustness. The simulation results show that the corresponding system responses have better quickness and some robustness, but the overshoot becomes a bit larger with contrast to traditional method.

Missile Autopilot Design for Agile Turn Control During Boost-Phase

This paper presents the air-to-air missile autopilot design for a <TEX>$180^{\circ}$</TEX> heading reversal maneuver during boost-phase. The missile's dynamics are linearized at a set of operating points for which angle of attack controllers are designed to cover an extended flight envelope. Then, angle of attack controllers are designed for this set of points, utilizing a pole-placement approach. The controllers' gains in the proposed configuration are computed from aerodynamic coefficients and design parameters in order to satisfy designer-chosen criteria. These design parameters are the closed-loop frequency, damping ratio, and time constant; these represent the characteristics of the control system. To cope with highly nonlinear and rapidly time varying dynamics during boost-phase, the global gain-scheduled controller is obtained by interpolating the controllers' gains over variations of the angle of attack, Mach number, and center of gravity. Simulation results show that the proposed autopilot design provides satisfactory performance and possesses good [ed: or "sufficient" or "excellent"] capabilities.

Multi-model approaches to three-axis missile autopilot design under aerodynamic roll angle uncertainty

The problem of designing a robust three-axis missile autopilot that operates under aerodynamic roll angle uncertainty is addressed in this article. A finite number of local state-space models over an aerodynamic roll angle envelope are developed as a multi-model to represent uncertainty bounds. Two design methods with multi-objective output-feedback control are proposed. In the first approach, a classical three-loop autopilot structure is slightly modified for the multivariable autopilot design. The optimal gains in the autopilot structure are automatically obtained by using a co-evolutionary optimization method that addresses competing specifications and constraints. In the second approach, the mixed H2/ H∞ performance criteria are guaranteed by multi-objective control synthesis via optimization techniques. Both design approaches are used in non-linear simulations with variations in the aerodynamic roll angle to provide satisfactory performance as a three-axis missile autopilot.

Missile Autopilot Design for Agile Turn Using Time Delay Control with Nonlinear Observer

This paper deals with missile autopilot design for agile turn phase in air-to-air engagement scenarios. To attain a fast response, angle-of-attack (AOA) is adopted for an autopilot command structure. Since a high operational AOA is generally required during the agile turn phase, dealing with the aerodynamic uncertainties can be a challenge for autopilot design. As a remedy, a new controller design method based on robust nonlinear control methodology such as time delay control is proposed in this paper. Nonlinear observer is also proposed to estimate the AOA in the presence of the model uncertainties. The performance of the proposed controller with variation of the aerodynamic coefficients is investigated through numerical simulations.

An improved decentralized control method for Bank-to-Turn missile autopilot design

In this paper, an improved decentralized control method is proposed to design a bank-to-turn (BTT) missile autopilot. Compared to the general diagonal blocked Lyapunov function method, the improved decentralized control method by considering the coupling terms as the structured uncertainty can provide a simpler design, tolerate more types of uncertainties and yield a better dynamic performance. Moreover, this method can be extended to multi-model systems expediently. Due to the structural constraints, the decentralized controller may not realize the tracking control target under some conditions, and this paper also provides such a condition. The decentralized controller design is formulated in terms of linear matrix inequality (LMI) optimization, and the simulation results demonstrate the effectiveness of the proposed method. Copyright © 2011 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society

Modeling of dynamics, guidance, and control systems of air-to-surface missiles

In this study, the generic dynamic models of air-to-surface missiles are given in addition to the related guidance and control schemes. In this extent, two-part missile configurations are considered as well as the traditional single-part missile geometries. The dynamic modelling part consists of the general equations of motion for both of the mentioned types of missile configurations, aerodynamic modelling and corresponding transfer functions, which are used in the design of missile autopilots. Further, the notable guidance laws applicable to such missiles are given along with the relevant autopilot, or missile control system, models. Regarding the mission profile of these munitions, the target is modelled as a surface vehicle moving on the ground. After conducting some computer simulations based on the proposed models, the study is concluded by a general evaluation section.

Adaptive dynamic surface control for integrated missile guidance and autopilot

Integrated guidance and control for homing missiles utilizing adaptive dynamic surface control approach is considered based on the three channels independence design idea. A time-varying integrated guidance and control model with unmatched uncertainties is first formulated for the pitch channel, and an adaptive dynamic surface control algorithm is further developed to deal with these unmatched uncertainties. It is proved that the proposed feedback controller can ensure not only the accuracy of target interception, but also the stability of the missile dynamics. Then, the same control approach is further applied to the control design of the yaw and roll channels. The 6-degree-of-freedom (6-DOF) nonlinear missile simulation results demonstrate the feasibility and advantage of the proposed integrated guidance and control design scheme.

A Generic Approach to Missile Autopilot Design using State-Dependent Nonlinear Control

AbstractThe fundamental objective of autopilot design for missile systems is to provide stability with satisfactory performance and robustness over the whole range of flight conditions throughout the entire flight envelope that missiles are required to operate in, during all probable engagements. Depending on the control mode (skid-to-turn or bank-to-turn), intercept scenario (such as surface to surface, surface to air, air to air) and mission phase (launch, midcourse, terminal), missile autopilots can command accelerations, body rates, incidence angles, or flight path angles. To this end, classical and modern multivariable techniques from linear control theory combined with gain scheduling have dominated missile autopilot design over the past several decades. In this paper, the concept of extended linearization (also known as state-dependent coefficient parameterization) is examined for state-dependent nonlinear formulation of the vehicle dynamics in a novel and very general form for the development of a generic and practical autopilot design approach for missile flight control systems. Any extended linearization control method, such as the currently popular State-Dependent Riccati Equation (SDRE) methods, can then be applied to this state-dependent formulation for missile flight control system design. The unique contribution of this paper is the novel use of a very general and realistic nonlinear aerodynamic model that captures all major aerodynamic nonlinearities attributed to missiles, together with the fully nonlinear and coupled 6-DOF equations of motion of rigid-body missile dynamics for full-envelope, 3-axes nonlinear autopilot design, without invoking any of the usual simplifying assumptions of the traditional linear design philosophy, and independent of any flight or trim conditions. Moreover, in the development of the generic approach, all the autopilot command structures mentioned above are incorporated in one compact topology. Practical considerations such as actuator dynamics and actuator position and rate saturation are also included in the development of the nonlinear autopilot. The proposed approach has been implemented and its performance and robustness validated in detailed 6-DOF simulations in three dimensional environments, using various missile configurations with stable, unstable and nonminimum-phase characteristics.

A multi-model approach to gain-scheduling control for agile missile autopilot design

AbstractThis paper presents a multi-model approach to the design of a robust gain-scheduled missile autopilot subject to rapid change in the dynamic stability during boost-phase. In this approach, a set of local controllers is designed for a family of multi-models to represent uncertainty bounds over a flight envelope. The application of linear matrix inequalities (LMIs) and ν-gap metric combined into the multi-model approach permits a robust gain-scheduling scheme to be systematically accomplished. As a result, the design of the overall gain-scheduled autopilot is formulated as a set of linear matrix inequalities given by desired performance requirements. Simulation results are conducted for a heading reversal maneuver over rapid center of gravity variation to show stability and performance robustness of the proposed approach.

Improving the Performance of Existing Missile Autopilot Using Simple Adaptive Control

AbstractA simple add-on adaptive control algorithm is presented. It is demonstrated via example that the performance of existing missile autopilot can be improved. The algorithm involves the synthesis of parallel feedforward which guarantees that the controlled plant is almost strictly positive real (ASPR). It is proved in the paper that such a parallel feedforward always exists. The proof is based on the parameterization of a set of stabilizing controllers. This parameterization enables straight-forward design and implementation of the add-on simple adaptive control (SAC) algorithm.

Three-Axis Autopilot Design for a High Angle-Of-Attack Missile Using Mixed H2/H∞Control

We report on the design of a three-axis missile autopilot using multi-objective control synthesis via linear matrix inequality techniques. This autopilot design guarantees <TEX>$H_2/H_{\infty}$</TEX> performance criteria for a set of finite linear models. These models are linearized at different aerodynamic roll angle conditions over the flight envelope to capture uncertainties that occur in the high-angle-of-attack regime. Simulation results are presented for different aerodynamic roll angle variations and show that the performance of the controller is very satisfactory.

A Design Method of BTT Missile Autopilot with the Impact of Feedforward

In order to solve the feedforward problem of traditional back-to-turn (BTT) missile autopilot, this paper proposed a controller design method considering the forward effect. Firstly, according to the three-channel mathematic model of BTT missile, we built a mathematic model of autopilot control system. Secondly, by employing the Nussbaum-type gain technique as well as the adding a power integrator design, and based on the design needs of tracking and controlling overload steadily, we proposed a global nonlinear control strategy, and then designed a continuous nonlinear autopilot, which solved the feedforward problem of BTT missile on pitching channel. Thirdly, we strictly proved the stability of the control system in finite time by applying the method of Lyapunov stability theory. Finally, we gave a simulation example to show that the designed control system not only overcome the influence of uncertain factors and the problem of the stable error, but also improved the tracking precision.

A composite sliding mode autopilot design

Sliding mode control has been applied to the design of many missile autopilots. In this paper, a control method with the primary feedback being proportional to the switching is developed for eliminating the disturbance effect due to model uncertainty. With this control method, a sliding mode autopilot is analysed. Then, a composite sliding mode control strategy is discussed to reduce the switching frequency. Numerical simulation results show a good performance of the composite control system.

Missile Autopilot Design: Gain-Scheduling and the Gap Metric

This paper presents a systematic methodology for the synthesis of global gain-scheduled controllers for nonlinear time-varying systems. A controller of this type is used to compute the pitch-axis autopilot of an air-air missile. The missile model used is considered a benchmark for testing autopilot controllers in the academic and industrial communities. The missile's dynamics are linearized at a small set of operating points for which proportional― integral/proportional-type controllers are designed, to shape the frequency response of the linear plants' dynamics. A new set of operating points is computed afterward using the connection between the gap metric and the H ∞ loop-shaping theory. Then, reduced-order, static, H ∞ loop-shaping controllers are designed for this set of points using linear matrix inequality optimization techniques. Finally, the global gain-scheduled controller is obtained by interpolating the proportional―integral/proportional and the loop-shaping controllers' gains over the missile's flight envelope. The simulation results given show the generality and effectiveness ofthe proposed control strategy in terms of the operating point selection, stability, performance and robustness, of the closed loop.

Integrated Higher-Order Sliding Mode Guidance and Autopilot for Dual Control Missiles

An integrated autopilot and guidance algorithm, robust to target maneuvers and missile’s model uncertainties, is developed using higher-order sliding mode control for interceptors steered by a combination of aerodynamic lift, sustainer thrust, and center-of-gravity divert thrusters. A smooth higher-order sliding mode guidance that is robust to target maneuvers generates flight-path trajectory angular rates and attitude rate commands. The attitude rate missilemaneuvers are aimed at producing desired aerodynamic lift and/or orienting the sustainer thrust. The lateral acceleration created by themissile attitudemaneuver is treated as a cooperative disturbance andaccounted for by the trajectory control. Robust to themissile’smodel uncertainties, higher-order (second-order) slidingmode autopilot is designed based on a nonlinear dynamic slidingmanifold. The proposed integrated autopilot and guidance algorithm also includes seeker/tracker bore-sight stabilization and estimation of target lateral acceleration. The algorithm is tested using computer simulations against a ballistic maneuvering target.

Global stabilizing controller design for linear time-varying systems and its application on BTT missiles

A parametric method for the gain-scheduled controller design of a linear time-varying system is given. According to the proposed scheduling method, the performance between adjacent characteristic points is preserved by the invariant eigenvalues and the gradually varying eigenvectors. A sufficient stability criterion is given by constructing a series of Lyapunov functions based on the selected discrete characteristic points. An important contribution is that it provides a simple and feasible approach for the design of gain-scheduled controllers for linear time-varying systems, which can guarantee both the global stability and the desired closed-loop performance of the resulted system. The method is applied to the design of a BTT missile autopilot and the simulation results show that the method is superior to the traditional one in sense of either global stability or system performance.

Integrated Roil-Pitch-Yaw Autopilot Design for Missiles

An roll-pitch-yaw integrated autopilot for missiles is designed for compensation of dynamics coupling. The proposed autopilot is based on the classical control technique. The gains of the proposed autopilot are optimized by using co-evolutionary augmented Lagrangian method(CEALM). Several cost functions are compared in order to find feasible control gains. For a case that a bank angle of missiles is unknown, multiple models are used in the autopilot optimization. In nonlinear simulations as well as linear simulations, the proposed autopilot provided good performances.

Formula omitted] and [formula omitted] performance analysis and gain-scheduling synthesis for parameter-dependent systems

This paper focuses on quadratic performance analysis and output feedback gain-scheduling synthesis for parameter-dependent systems with linear fractional representations (LFRs). New quadratic H 2 and L 2 performance analysis results based on full-block multipliers are given. A novel gain-scheduling output feedback synthesis, which can be regarded as a natural extension of the loop shaping design procedure of McFarlane and Glover to parameter-dependent systems, is proposed. This gain-scheduling technique is computationally attractive and yields a simple and transparent control structure that can be easily implemented. Its effectiveness is illustrated on a benchmark missile autopilot example.

Novel backstepping design for blended aero and reaction-jet missile autopilot

The advanced missile uses blended control of aero-fin and reaction-jet to improve missile maneuverability. The blended control design, which is multi-inputs and multi-outputs (MIMO), severe nonlinear, and model uncertain, is much more complex than conventional aero-fin control. A novel nonlinear backstepping control approach is proposed to design the blended autopilot. Missile model is reformed to a new one by state reconstruction technique so that it is easy to be handled by the backstepping method. Then a Lyapunov function is chosen to avoid oscillation caused in normal backstepping way when control parameters are mismatched. In distribution of both inputs, optimal energy logic is proposed. In addition, a fuzzy cerebellar model articulation controller (FCMAC) neural network is used to guarantee controller robustness to uncertainties. Finally, simulation results demonstrate the efficiency and advantages of the proposed method.

Integrated Autopilot and Guidance for Dual Control Missiles Using Higher Order Sliding Mode Control and Observers

An integrated Autopilot-and Guidance Algorithm is developed using Higher Order Sliding Mode Control, for interceptors steered by combination of aerodynamic lift, sustainer thrust and center of gravity divert thrusters. A smooth HOSM guidance generates flight path trajectory angular rates and attitude rate commands. The attitude rate maneuvers are aimed at producing desired aerodynamic lift and / or orienting sustainer thrust. The lateral acceleration created by the attitude maneuver is treated as a “cooperative” disturbance and accounted for by the trajectory control. SOSM autopilot design is based on nonlinear dynamic sliding manifold. Proposed algorithm also includes seeker tracker, bore sight stabilization and estimation of target lateral acceleration. The algorithm is tested using computer simulations against a ballistic maneuvering target.