Showing papers on "Missile published in 2006"

Impact-time-control guidance law for anti-ship missiles

Abstract: In this paper, a new guidance problem with the impact time constraint is investigated, which can be applied to salvo attack of anti-ship missiles. The closed form solution based on the linear formulation is derived, suggesting an additional loop for adjusting the impact time in addition to the traditional optimal guidance loop. This solution is a combination of the well-known PNG law and the feedback of the impact time error, which is the difference between the impact time by PNG and the prescribed impact time. The new guidance law called ITCG (Impact-Time-Control Guidance) can be used to guide multiple missiles to hit a stationary target simultaneously at a desirable impact time. Nonlinear simulation of several engagement situations demonstrates the performance and feasibility of ITCG. In addition, the similarity of the closed form solution and APNG is investigated and the switching rule for practical implementation is discussed.

Sliding-Mode Control for Integrated Missile Autopilot Guidance

Abstract: A sliding-mode controller is derived for an integrated missile autopilot and guidance loop. Motivated by a differential game formulation of the guidance problem, a single sliding surface, defined using the zero-effort miss distance, is used. The performance of the integrated controller is compared with that of two different two-loop designs. The latter use a sliding-mode controller for the inner autopilot loop and different guidance laws in the outer loop: one uses a standard differential game guidance law, and the other employs guidance logic based on the sliding-mode approach. To evaluate the performance of the various guidance and control solutions, a two-dimensional nonlinear simulation of the missile lateral dynamics and relative kinematics is used, while assuming first-order dynamics for the target evasive maneuvers. The benefits of the integrated design are studied in several endgame interception engagements. Its superiority is demonstrated especially in severe scenarios where spectral separation between guidance and flight control, implicitly assumed in any two-loop design, is less justified. The results validate the design approach of using the zero-effort miss distance to define the sliding surface.

Time-to-go weighted optimal guidance with impact angle constraints

Abstract: In this paper, the optimal guidance law with terminal constraints of miss distance and impact angle is presented for a constant speed missile against the stationary target. The proposed guidance law is obtained as the solution of a linear quadratic optimal control problem with the energy cost weighted by a power of the time-to-go. Systematic selection of guidance gains and trajectory shaping are possible by adjusting the exponent of the weighting function. A new time-to-go calculation method taking account of the trajectory curve is also proposed for implementation of the proposed law. Nonlinear and adjoint simulations are performed to investigate the performance of the proposed guidance law and time-to-go calculation method.

Integrated Guidance and Control of Missiles With $theta hbox - D$ Method

Abstract: A new suboptimal control method is proposed in this study to effectively design an integrated guidance and control system for missiles. Optimal formulations allow designers to bring together concerns about guidance law performance and autopilot responses under one unified framework. They lead to a natural integration of these different functions. By modifying the appropriate cost functions, different responses, control saturations (autopilot related), miss distance (guidance related), etc., which are of primary concern to a missile system designer, can be easily studied. A new suboptimal control method, called the thetas-D method, is employed to obtain an approximate closed-form solution to this nonlinear guidance problem based on approximations to the Hamilton-Jacobi-Bellman equation. Missile guidance law and autopilot design are formulated into a single unified state space framework. The cost function is chosen to reflect both guidance and control concerns. The ultimate control input is the missile fin deflections. A nonlinear six-degree-of-freedom (6-DOF) missile simulation is used to demonstrate the potential of this new integrated guidance and control approach

Generalized Vector Explicit Guidance

Abstract: This paper proposes and evaluates a new guidance law termed generalized vector explicit guidance (GENEX). This guidance law can simultaneously achieve design specifications on miss distance and final missile-target relative orientation. The latter may be used to enhance the performance of warheads the effectiveness of which is influenced by the terminal encounter geometry. The GENEX guidance law is parameterized in terms of a design coefficient that determines the degree of curvature in the trajectory. Feasibility of GENEX guidance was demonstrated by its application to two weapon scenarios. The first was an air-to-air missile terminal homing scenario. Assuming ideal sensor information and a single-lag missile response model, the guidance was shown to perform well against an air target performing evasive maneuvers. A specified zero-aspect terminal encounter angle was achieved while simultaneously minimizing miss distance. The second application involved an air-to-surface munition released from an unmanned air vehicle. The GENEX guidance law was able to produce trajectories satisfying a terminal impact angle constraint. In addition, an engagement region of sufficient size was shown to be achievable using guidance gains scheduled with target location and weapon release altitude.

Circular-Navigation-Guidance Law for Precision Missile/Target Engagements

Abstract: A new precision guidance law with impact angle constraint for a two-dimensional planar intercept is presented. It is based on the principle of following a circular arc to the target, hence the name circular navigation guidance. The guidance law does not require range-to-target information. We prove that it attains a perfect intercept under certain ideal conditions. In a broader range of conditions, it is shown to perform favorably when compared to another law from the literature.

Optimal Path Planning for Unmanned Combat Aerial Vehicles to Defeat Radar Tracking

Abstract: The problem of path planning for unmanned combat aerial vehicles (UCAVs) in the presence of radar-guided surface-to-air missiles is treated The problem is formulated in the framework of the interaction between three subsystems: the aircraft, the radar, and the missile The main features of this integrated model are as follows The aircraft radar cross section (RCS) depends explicitly on both the aspect and bank angles; hence, the RCS and aircraft dynamics are coupled The probabilistic nature of radar tracking is accounted for, namely, the probability that the aircraft has been continuously tracked depends on the aircraft RCS and range Finally, the requirement to maintain tracking before missile launch and during missile flyout are also modeled Based on this model, the problem of UCAV path planning is formulated as a minimax optimal control problem, with the aircraft lateral acceleration serving as control Necessary conditions of optimality for this minimax problem are derived and used as a basis for an efficient numerical solution Illustrative examples are considered that confirm the standard flying tactics of “denying range, aspect, and aim,” by yielding flight paths that weave to avoid long exposures of aspects with large RCS HIS paper is devoted to the problem of automated path planning for unmanned combat aerial vehicles (UCAVs) in the presence of radar-guided surface-to-air missiles (SAMs) This problem features the interaction between three subsystems: the aircraft and its characteristics, the radar and its capabilities, and the missile and its lethality Therefore, the solution of the UCAV path-planning problem requires realistic models of these three subsystems Although the current literature offers models for each of them separately, there is no approach that integrates models of the three subsystems in a unified framework The purpose of this paper is to propose such an integrated model and present results on its use

Guidance Laws for Anti-Ship Missiles Using Impact Angle and Impact Time

Abstract: *† The general objective of most guidance laws is to guide a missile into a collision course so that the missile intercepts a target effectively under several constraint conditions. As the defense system for warships has been advanced recently, many researchers are working on the development of new guidance laws for anti-ship missiles. This paper deals with an impact angle based guidance law and an impact time based guidance law. The impact angle guidance law can be used to generate appropriate trajectories and intercept a target with desired impact angle. How to geometrically set the waypoint passing angles as well as the desired impact angle are proposed. The impact time guidance law based on proportional navigation guidance is also proposed in this paper. The proposed guidance law can be applied for the formation flight of anti-ship missiles. As several missiles intercept a target simultaneously, the missiles can complete the given mission more efficiently. Finally the two guidance laws are combined together to enhance the survivability and kill probability. Numerical simulations are performed to evaluate the performances of the proposed guidance laws using impact angle and impact.

Infrared Signatures of Low-Flying Aircraft and Their Rear Fuselage Skin's Emissivity Optimization

Abstract: This paper analyzes the main contributors of infrared (IR) signature in a typical aircraft on a low-altitude mission. Various computational models are used to predict IR radiation from the aircraft. The bands within IR spectrum in which aircraft are susceptible to a typical IR-guided surface-to-air and air-to-air missile, for typical cases of tactical relevance, are identified. Lock-on range for aircraft against a typical missile is also computed. The feasibility of a low-altitude mission against a ground-based IR-guided threat is analyzed. The technique of emissivity optimization of aircraft rear fuselage skin, for reducing its infrared signature, is introduced and compared with other IR signature suppression techniques. The effectiveness of this technique in enlarging the safe flight envelope of aircraft, with respect to threat from heat-seeking missiles, for both surface-to-air and air-to-air missiles, is demonstrated. It is found that earthshine reflected off the aircraft surface plays a crucial role in the effectiveness of this technique against a surface-to-air missile (SAM) in 8‐12 μm band. Nomenclature A = area, m 2 H = spectral irradiance, μW/μm · m 2 h = aircraft altitude, km I = spectral radiant intensity, W/Sr · μm · m 2 J = spectral radiance: comprising emission and earthshine, W/Sr · μm · m 2 L = length, m M = Mach number N = number of discretized elements NEI = noise equivalent irradiance, W/m 2 Rma = distance separating missile and aircraft, km

Projectile trajectory control system

Abstract: Trajectory is controlled by a control system having fins that de-spin a section of the control system relative to a projectile or missile. The control system also includes aero- surfaces that produce a lift when brought to rotation speed of about 0 Hz relative to a reference fame and a brake that couples the guidance package to the rotational inertia of the projectile or missile. In one example, no electric motor is used in the trajectory control system, saving weight and increasing reliability.

Integrated backstepping design of missile guidance and control with robust disturbance observer

Abstract: For homing missile weapon systems, integrated design of guidance and control using backstepping control with disturbance observer are studied. New guidance strategy with transversal velocity in LOS frame and Time to Go (tgo) is devised. The stability of integrated backstepping guidance and control logic is proven by Lyapunov sense. Tracking performance is also considered. The deflection command is a function of linear aerodynamic coefficients and measurable states. The designed guidance-control system performance is verified via numerical simulation.

Differential-game-based guidance law using target orientation observations

Abstract: Modern 4th generation air-to-air missiles are quite capable of dealing with today's battlefield needs. Advanced aerodynamics, highly efficient warheads and smart target acquisition systems combine to yield higher missile lethality than ever. However, in order to intercept highly maneuverable targets, such as future unmanned combat air vehicles (UCAV), or to achieve higher tracking precision for missiles equipped with smaller warheads, further improvement in the missile guidance system is still needed. A new concept is presented here for deriving improved differential-game-based guidance laws that make use of information about the target orientation, which is acquired via an imaging seeker. The underlying idea is that of using measurements of the target attitude as a leading indicator of target acceleration. Knowledge of target attitude reduces the reachable set of target acceleration, facilitating the computation of an improved estimate of the zero-effort miss (ZEM) distance. In consequence, missile guidance accuracy is significantly improved. The new concept is applied in a horizontal interception scenario, where it is assumed that the target maneuver direction, constituting a partial attitude information, can be extracted via processing target images, acquired by an imaging sensor. The derivation results in a new guidance law that explicitly exploits the direction of the target acceleration. The performance of the new guidance law is studied via a computer simulation, which demonstrates its superiority over existing state-of-the-art differential-game-based guidance laws. It is demonstrated that a significant decrease in the miss distance can be expected via the use of partial target orientation information.

Missile Controlled by Lift and Divert Thrusters Using Nonlinear Dynamic Sliding Manifolds

Abstract: A new approach to the design of a kinetic-kill longitudinal autopilot steering the missile trajectory by the combination of aerodynamic lift and divert thrusters (dual-thrusters control) and with its attitude oriented by attitude thrusters is presented. The proposed approach may increase the total divert acceleration capability by up to 100%, improving the end-game intercept accuracy, when such capability is required. The pitch plane autopilot design is based on second-order sliding mode control using a nonlinear dynamic sliding manifold technique. A robust high-accuracy tracking of the missile normal acceleration guidance command is achieved in the presence of considerable model uncertainties created by the interactions between the airflow and the thrusters jets. Results of the computer simulation demonstrate excellent, robust, high-accuracy tracking performance of the proposed design.

Bounded differential games guidance law for dual-controlled missiles

Abstract: A new guidance law tailored for an interceptor missile having forward and aft controls is proposed. The guidance law is derived using a differential games formulation with bounded controls. For the derivation, the interceptor closed-loop dynamics is represented by two first-order bi-proper transfer functions. Possible game-space structures are investigated, including a new one with two closed singular regions. The effect of the direct lift associated with the canard and tail controls is investigated, and it is proved that zero miss distance can always be guaranteed for some initial conditions. It is also shown that for the tail control a switching surface at some constant time before interception exists in the game-space, resulting from its nonminimum-phase nature.

Interceptor guidance for boost-phase missile defense

Abstract: A fire control system for a boost phase threat missile includes sensors for generating target-missile representative signals, and a multi-hypothesis track filter, which estimates the states of various target hypotheses. The estimated states are typed to generate hypotheses and their likelihoods. The states, hypotheses and likelihoods are applied to a multihypothesis track filter, and the resulting propagated states are applied to an engagement planner, together with the hypotheses and likelihoods. The engagement planner initializes the interceptor(s). Interceptor guidance uses the initialization and the propagated states and typing information to command the interceptor.

Endgame Guidance and Relative Navigation of Strategic Interceptors with Delays

Abstract: This paper is concerned with endgame guidance and relative navigation of strategic missiles equipped with divert thrusters to intercept nonmaneuvering reentry vehicles. The paper has three objectives: 1) demonstrate superiority of predictive guidance to pulsed proportional navigation guidance; 2) devise compensation for a onesample delay in arrival of line-of-sight (LOS) angle measurements at Kalman-filter module and another one-sample delay in communication of LOS rate estimates to the guidance module; and 3) develop a Kalman filter insensitive to modeling errors for relative navigation. A hybrid Kalman filter is developed for relative navigation with angle measurements—hybrid because relative position and velocity vectors are propagated in Cartesian coordinates, whereas the error covariance is propagated, and updated at the time of measurement, in spherical coordinates. For spherical computations, a time-to-go dependent transition matrix and a time-to-go dependent process noise matrix are formulated. It is shown that these time-to-go dependent matrices reduce the miss distance and its sensitivity to modeling errors. With this Kalman filter, it is shown that the closed-loop predictive guidance yields smaller miss distance, consumes less fuel, and requires fewer divert firings than the pulsed proportional navigation guidance does. The delay compensation is accomplished in two steps: first, the high-frequency stream of ∆V measurements from an accelerometer is stored and synchronized with the delayed LOS angle measurement from the seeker; second, the delayed LOS rate estimate from the Kalman filter is propagated forward using the measured ∆V that transpires during the delay. The miss distance of the zero-delay level and robustness to modeling errors is shown to be almost recovered.

Decision-Directed Adaptive Estimation and Guidance for an Interception Endgame

Abstract: A new integrated estimation and guidance design approach is presented as a computationally effective procedure for interception of maneuvering targets. This is an adaptive approach that uses the following elements: banks of state estimators, and guidance laws, a maneuver detector for the onset of the target’s maneuver, and a hierarchical decision law for online selection of the estimator/guidance law pair to be employed. Simulation results confirm that the adaptive approach leads to a reduction in the miss distance as compared with cases in which only a single estimator/guidance law combination is available. LTHOUGH the study presented in this paper was motivated by a future ballistic missile defense (BMD) scenario, it addresses a more general problem, namely, the interception of a randomly maneuvering target by a guided missile in an environment of noise-corrupted measurements. The missile guidance endgame is an imperfect information terminal control problem with a very short horizon and it requires a design approach different from the one used in other control systems. In the classical approach, a linearized model of the dynamic process about a nominal set point is first derived. For this linearized model, the estimator and the control law are designed independently. The separate design is based on assuming the validity of the certainty equivalence principle (CEP) and the associated separation theorem (ST). 1

Homeland Security: Protecting Airliners from Terrorist Missiles

Abstract: Recent events have focused attention on the threat that terrorists with shoulder fired surface-to-air missiles (SAMs), referred to as Man-Portable Air Defense Systems (MANPADS), pose to commercial airliners. This report discusses SAMs and examines options for mitigating missile threats.

Multihypothesis threat missile propagator for boost-phase missile defense

Abstract: A fire control system for a boost phase threat missile includes sensors for generating target-missile representative signals, and a multi-hypothesis track filter, which estimates the states of various target hypotheses. The estimated states are typed to generate hypotheses and their likelihoods. The states, hypotheses and likelihoods are applied to a multihypothesis track filter, and the resulting propagated states are applied to an engagement planner, together with the hypotheses and likelihoods. The engagement planner initializes the interceptor(s). Interceptor guidance uses the initialization and the propagated states and typing information to command the interceptor.

Novel Adaptive Generalized Likelihood Ratio Detector with Application to Maneuvering Target Tracking

Abstract: A novel adaptive jump-detection algorithm is introduced for scenarios involving abrupt changes in the inputs to linear systems, such as those that might occur in tracking maneuvering targets. Improving upon the standard generalized likelihood ratio (GLR) detector, presented over two decades ago, the new algorithm is characterized by increased robustness with respect to uncertainties in the system input, which frequently arise in the context of target tracking applications. The performance of the new algorithm is demonstrated in an endgame scenario involving an interceptor missile and a maneuerable tactical ballistic missile. An extensive Monte Carlo simulation study is used to demonstrate the superiority of the method over the conventional GLR method in terms of its much smaller observed false alarm probability, which actually agrees with the theoretical value. The new algorithm also facilitates a correct isolation of the abrupt change, is consistent in the usual statistical sense, and generally proves more reliable.

An ontology for trajectory simulation

Abstract: From the concept exploration for a weapon system to training simulators, from hardware-in-the-loop simulators to mission planning tools, trajectory simulations are used throughout the life cycle of a weapon system. A trajectory simulation can be defined as a computational tool to calculate the flight path and flight parameters of munitions. There is a wide span of trajectory simulations differing widely with respect to their performance and fidelity characteristics, from simple point-mass simulations to six--seven degrees of freedom hardware-in-the-loop missile simulations. From our observations, it is a common practice in the industry that developments of these simulations are carried out as isolated projects although they rely on the same body of knowledge. We envision an ontology that will capture the common knowledge in trajectory simulation domain and make domain knowledge available for reuse. Trajectory Simulation Ontology, dubbed TSONT, is being developed to realize this vision.

Guidance Law Design for Missiles with Reduced Seeker Field-Of-View

Abstract: In this paper, a missile guidance law is designed to address the reduced seeker field-of-view constraint that is required in the low cost weapon system. The guidance problem is formulated as a nonlinear optimal control problem in the polar coordinates such that the line-of-sight (LOS) can be explicitly controlled. A closed-form guidance law is obtained by employing the D θ − nonlinear control technique. By virtue of state dependent weighting functions, impact angle requirement for increasing weapon lethality can also be met while satisfying reduced seeker field-of-view constraint. A missile attacking a stationary target is considered in this study. The simulation demonstrated favorable results compared with the classical proportional navigation law in terms of satisfying both reduced seeker field-of-view constraint and the terminal impact angle requirement.

Jettisonable nosecone and missile with a jettisonable nosecone

Abstract: A jettisonable nosecone (10) for a missile is specified, which nosecone (10) is longitudinally split into at least two parts (15, 16) and is held together by detachable connecting structures, in which case the connecting structures are designed to actively move the at least two parts (15, 16) away from one another when released. A missile having a correspondingly designed nosecone (10) is also provided. A nosecone (10) of this type allows simple jettisoning during every flight phase of the missile, and is also suitable for retrofitting to an already existing missile.

Guidance and Autopilot for Missiles Steered by Aerodynamic Lift and Divert Thrusters Using Second Order Sliding Mode Control

Abstract: A new smooth second-order sliding mode control is proposed and proved for a system driven by uncertain sufficiently smooth disturbances. The main target application of this technique (combined with second order sliding mode control based on a nonlinear dynamic sliding manifold) - the guidance-control of a kinetic-kill missile against targets performing evasive maneuvers with an autopilot steering the missile trajectory by the combination of aerodynamic lift and divert-thrusters (dual-thrusters control) and with its attitude oriented by attitude-thrusters is presented. The proposed approach, being robust to target maneuvers, may increase the total divert acceleration capability by up to 100% improving the “end-game” intercept accuracy, when such capability is required. A robust high accuracy tracking of the missile normal acceleration guidance command is achieved in presence of considerable model uncertainties created by the interactions between the airflow and the thrusters jets. The designed second order sliding mode control-based robust guidance-control system performance is verified via computer simulations.

Missile control system and method

Abstract: A missile (10) includes a tail section (12) having a multi-nozzle grid (16) with both fixed nozzles (20), and movable, thrust vector nozzles (22). The movable nozzles may be configured in a number of discrete array bars (32a-32d), each containing multiple of the movable nozzles. Movement of one or more array bars may be used to vector the thrust of the missile, providing roll, yaw, or spinning of the missile, for example.

Boost phase intercept missile fire control system architecture

Abstract: A fire control system for a boost phase threat missile includes sensors for generating target-missile representative signals, and a multi-hypothesis track filter, which estimates the states of various target hypotheses. The estimated states are typed to generate hypotheses and their likelihoods. The states, hypotheses and likelihoods are applied to a multihypothesis track filter, and the resulting propagated states are applied to an engagement planner, together with the hypotheses and likelihoods. The engagement planner initializes the interceptor(s). Interceptor guidance uses the initialization and the propagated states and typing information to command the interceptor.