Showing papers on "Missile published in 2002"

Missile autopilot design via a multi‐channel LFT/LPV control method

Abstract: In this paper, the missile pitch-axis autopilot design is revisited using a new and recently available linear parameter-varying (LPV) control technique. The missile plant model is characterized by a linear fractional transformation (LFT) representation. The synthesis task is conducted by exploiting new capabilities of the LPV method: firstly, a set of H2/H∞ criteria defined channel-wise is considered; secondly, different Lyapunov and scaling variables are used for each channel/specification which is known to reduce conserva tism; and finally, the controller gain-scheduling function is constructed as affine matrix-valued function in the polytopic co-ordinates of the scheduled parameter. All these features are examined and evaluated in turn for the missile control problem. The method is shown to provide additional flexibility to tradeoff conflicting and demanding performance and robustness specifications for the missile while preserving the practical advantage of previous single-objective LPV methods. Finally, the method is shown to perform very satisfactorily for the missile autopilot design over a wide range of operating conditions. Copyright © 2001 John Wiley & Sons, Ltd.

Recursive time-to-go estimation for homing guidance missiles

Abstract: This paper addresses the problem of computing accurate time-to-go estimates, which is an important issue in implementing various optimal guidance laws developed for missiles of time-varying velocity. A recursive time-to-go computation method which updates the time-to-go in a noniterative way is presented. The recursive method includes an error compensation feature which explicitly computes the time-to-go error produced by nonzero initial heading errors. The proposed method is simple and straightforward to implement for any missile velocity profiles. Various numerical examples show that the proposed method works effectively for optimal guidance laws as well as proportional navigation and augmented proportional navigation.

Circular navigation guidance law for precision missile/target engagements

Abstract: Presents a precision guidance law with impact angle constraint for a two-dimensional planar intercept. It is based on the principle of following a circular arc to the target, hence the name "circular navigation guidance" (CNG). This law is shown mathematically to be successful over a wide range of initial conditions. Computer simulations show that CNG performs much better than an equivalent law from the literature, and that it outperforms the standard proportional navigation guidance law in terms of miss distance. A simplified law is presented that can be used without range-to-target information.

Nonorthodox guidance law development approach for intercepting maneuvering targets

Abstract: Two aspects of a new mindset are applied to interceptor guidance: 1) the mathematical formulation of an interception scenario against maneuverable targets and 2) the relationship between the estimation process and optimalguidance law design. The interception of a maneuverable antisurface missile is formulated as a zero-sum pursuit evasion game. The perfect information game solution, which guarantees a robust hit-to-kill homing accuracy, requires, among other things, the knowledge of the target maneuver. This variable cannot be directly measured and has to be estimated based on noisy measurements. The greatest error source in the estimation of time-varying target maneuvers is the inherent delay due to the convergence time of the process. The estimation process is modeled as a pure information delay. Such a delay is partially compensated by a new guidance law based on the solution of a delayed information pursuit-evasion game. The new approach represents a potential breakthrough in guidance law design predicting reduced miss distances and robustness even in stressing interception environments. The improved accuracy is confirmed by a set of Monte Carlo simulations in a ballistic missile interception scenario with noisy measurements.

State-constrained agile missile control with adaptive-critic-based neural networks

Abstract: In this study, we develop an adaptive-critic-based controller to steer an agile missile that has a constraint on the minimum flight Mach number from various initial Mach numbers to a given final Mach number in minimum time while completely reversing its flightpath angle. This class of bounded state space, free final time problems is very difficult to solve due to discontinuities in costates at the constraint boundaries. We use a two-neural-network structure called "adaptive critic" in this study to carry out the optimization process. This structure obtains an optimal controller through solving optimal control-related equations resulting from a Hamiltonian formulation. Detailed derivations of equations and conditions on the constraint boundary are provided. For numerical experiments, we consider vertical plane scenarios. Flight Mach number and the flightpath angle are the states and the aerodynamic angle of attack is treated as the control. Numerical results bring out some attractive features of the adaptive critic approach and show that this formulation works very well in guiding the missile to its final conditions for this state constrained optimization problem from an envelope of initial conditions.

Real-time computational methods for SDRE nonlinear control of missiles

Abstract: Computational speed and performance issues arising in the practical implementation of the state dependent Riccati equation (SDRE) technique are discussed. A software package for real-time implementation of the SDRE technique was developed during the present research. The execution of this software at speeds up to 2 kHz sample rates on problems of the size commonly encountered in missile flight control applications is then demonstrated on commercial off-the-shelf processors.

Nonlinear fuzzy H/sub /spl infin// guidance law with saturation of actuators against maneuvering targets

Abstract: A nonlinear H/sub /spl infin// guidance law based on a fuzzy model is proposed for tactical missiles pursuing maneuvering targets in three-dimensional (3-D) space. In the proposed guidance scheme, the relative motion equations between the missile and target are first interpolated piecewise by Takagi-Sugeno linear fuzzy models. Then, a nonlinear fuzzy H/sub /spl infin// guidance law is designed to eliminate the effects of approximation error and external disturbances to achieve the desired goal. The linear matrix inequality (LMI) technique is then employed to treat this H/sub /spl infin// optimal guidance design in consideration of control constraints. Finally, the problem is further transformed into a standard eigenvalue problem so that it can be efficiently solved via a convex optimization algorithm, which is available from a numerical computation software.

Line-of-sight rate estimation and linearizing control of an imaging seeker in a tactical missile guided by proportional navigation

Abstract: Acceleration commands in missiles guided by proportional navigation require the measurement of line-of-sight (LOS) rate. It is often obtained by filtering the output of a 2-DOF rate gyro mounted on the inner gimbal of the seeker. This paper describes the modeling of an imaging seeker and the formulation of an extended Kalman filter (EKF) for the estimation of LOS rate from measurements of relative angular displacement between seeker gimbals and a low-cost strapdown inertial unit. The approach aims at circumventing the need for the rate gyro on the seeker. A linearizing feedback control law for decoupling missile motion from that of the seeker is proposed based on the filter model and its estimates. Additionally, the control law uses visual information from the image sequence for target tracking. Seeker dynamics and control are then integrated into a dynamic model of a cruciform missile equipped with canards and rollerons and guided by proportional navigation in 3D interception tasks. Monte Carlo simulation is employed to evaluate the overall system accuracy subject to different initial conditions and the impact of rolling motion during high-g maneuvers on miss distance. Initial engagement geometry and roll-rate damping at high incidence angles have significant effect.

Guidance Law Design by Adaptive Fuzzy Sliding-Mode Control

Abstract: This paperproposes three fuzzy-logic-basedcommandsto line-of-sightguidance laws. Theprinciple of command to line-of-sight guidance is to force a missile to  y as close as possible along the instantaneous line of sight joining the ground tracker and the target. First, the fuzzy logic control and the fuzzy sliding-mode control guidance laws are presented. In addition, an adaptive fuzzy sliding-modecontrol designmethod is developed and is applied for the command to line-of-sight guidance law design. In the design of the adaptive fuzzy sliding-mode control guidance law, the adaptive laws based on a Lyapunov function are developed to adjust the parameters of the fuzzy rules and the uncertainty bound. Thus, the stability of the system can be guaranteed. Finally, two engagement scenarios are examined and a comparison between the proposed fuzzy logic control guidance law, fuzzy sliding-mode control guidancelaw,adaptivefuzzy sliding-modecontrolguidancelaw,andamodel-basedfeedback linearizationguidance law is made.

Ship self-defense missile weapon system

Abstract: The present invention provides a ship self-defense missile (SSDM) weapon system for launching a plurality of light weight missiles from an existing vertical tube launch infrastructure. The system for vertically launching missiles from a ship comprises a plurality of tiers having a top tier and a bottom tier in which tier supports a plurality of missiles. The tiers are set into a launch canister having an interior wall to form a vertical stack in the launch canister. A launch means is used for selectively launching at least one of the plurality of missiles from the top tier. A means for ejecting ejects the top tier is depleted of missiles. A vertical movement means raises and lowers the tiers within the launch tube and the vertical movement means raises next tier in the vertical stack into a position to launch. Preferably, the vertical movement means is a jack screw threaded though each tier in the vertical stack and the means for ejecting involves screwing a depleted tier off the jack screw and initiating explosives at the base of the depleted tier to allow the next tier access to a ready to fire position.

Multi-purpose missile launcher system for a military land vehicle

Abstract: A multi-purpose missile launcher system for a military land vehicle that has the capability for direct targeting both short and medium range land targets, as well launching missiles against longer-range land targets or air targets using indirect targeting. The multi-purpose missile launcher system is deployed as part of a modular weapon system that mates with a modular bed of the military land vehicle.

Three-dimensional midcourse guidance using neural networks for interception of ballistic targets

Abstract: A suboptimal midcourse guidance law is obtained for interception of free-fall targets in the three-dimensional (3D) space. Neural networks are used to approximate the optimal feedback strategy suitable for real-time implementation. The fact that the optimal trajectory in the 3D space does not deviate much from a vertical plane justifies the use of the two-dimensional (2D) neural network method previously studied. To regulate the lateral errors in the missile motion produced by the prediction error of the intercept point, the method of feedback linearization is employed. Computer simulations confirm the superiority of the proposed scheme over linear quadratic regulator guidance and proportional navigation guidance as well as its approximating capability of the optimal trajectory in the 3D space.

History and the Current Status of the Russian Early-Warning System

Abstract: This article presents an overview of the history of development and the current status of the Soviet and Russian early-warning system, which was built to provide the Soviet strategic forces with information about a missile attack in an event of a nuclear conflict with the United States. Two main components of this system are considered--the network of early-warning radars, and the space-based early-warning system, which includes satellites on highly-elliptical and geosynchronous orbits. The system appears to be capable of detecting a massive attack, but cannot be relied upon to detect individual missile launches.

Numerical Simulation of Rolling-Airframes Using a Multi-Level Cartesian Method

Abstract: A supersonic rolling missile with two synchronous canard control surfaces is analyzed using an automated, inviscid, Cartesian method. Sequential-static and time-dependent dynamic simulations of the complete motion are computed for canard dither schedules for level flight, pitch, and yaw maneuver. The dynamic simulations are compared directly against both high-resolution viscous simulations and relevant experimental data, and are also utilized to compute dynamic stability derivatives. The results show that both the body roll rate and canard dither motion influence the roll-averaged forces and moments on the body. At the relatively, low roll rates analyzed in the current work these dynamic effects are modest, however the dynamic computations are effective in predicting the dynamic stability derivatives which can be significant for highly-maneuverable missiles.

Coupled Aeroheating/Ablation Analysis for Missile Configurations

Abstract: A method for high-fidelity surface temperature and thermal transient calculations for missile configurations is described. The key technical requirements for these predictions are accurate heat transfer coefficient distributions as functions of time and a coupled, transient thermal solution. These requirements have been met by integrating the capabilities of two computer codes. The Maneuvering Aerotherm Shape Change Code is used to determine the convective boundary conditions based on a prescribed trajectory. At each time step, these boundary conditions are applied to the surface nodes. The Charring Material Thermal Response and Ablation Program is used to determine the conduction of heat into the body, the charring of the materials, and ablation from the surface during the time step. This explicit coupling is continued throughout the entire flight. The methodology is verified with comparisons to the arc heater and flight-test data. A final demonstration of the code's capability is shown with a lethality sled test on an airframe prototype subjected to multiple environmental mediums (air/helium).

An Aerodynamic Analysis of a Spinning Missile with Dithering Canards

Abstract: A generic spinning missile with dithering canards is used to demonstrate the utility of an overset structured grid approach for simulating the aerodynamics of rolling airframe missile systems. The approach is used to generate a modest aerodynamic database for the generic missile. The database is populated with solutions to the Euler and Navier-Stokes equations. It is used to evaluate grid resolution requirements for accurate prediction of instantaneous missile loads and the relative aerodynamic significance of angle-of-attack, canard pitching sequence, viscous effects, and roll-rate effects. A novel analytical method for inter- and extrapolation of database results is also given.

Trajectory Optimization for Air-to-Surface Missiles with Imaging Radars

Abstract: The use of trajectory optimization techniques is presented for the terminal guidance of an air-to-surface missile using a Doppler beam sharpening (DBS) radar seeker. The terminal guidance problem is characterized by a stealthy terrain-following phase that is followed by a climb and dive onto the target (a "bunt" trajectory). The imaging properties of DBS radars impose additional azimuth plane constraints on the trajectory that have to be incorporated into the optimization process. The various mission phases are interrelated, and the performance objectives come into conflict with the hardware constraints. The trajectory optimizer is used to generate offline open-loop controls that satisfy the various mission requirements. Numerical examples are used to illustrate the method and its efficacy.

Control for uav operations under imperfect information

Abstract: We address Command and Control (C 2 ) problems for unmanned air vehicles (UAV’s) within the framework of stochastic games. The problem we consider involves one unit comprising a few UAV’s (typically in the range of two to ten) attacking a small number of targets. The targets are defended by surface-to-air missile (SAM) systems with missiles and associated search and track radars. The opponent may also employ decoy SAM radars. Our goal here is to develop a stochastic game formulation that can provide output feedback controls in the presence of uncertainty and partial information. We approach this goal by combining the estimator and controller via a modifled Certainy Equivalence Principle that weighs both the probability of each possible state and the potential cost such system state in a mathematically appropriate way, so as to determine a near optimal control.

Precision-guided hypersonic projectile weapon system

Abstract: A precision-guided hypersonic projectile weapon system. The inventive system includes a first subsystem for determining a target location and providing data with respect thereto. A second subsystem calculates trajectory to the target based on the data. The projectile is then launched and guided in flight along the trajectory to the target. In the Illustrative application, the projectile is a tungsten rod and the first subsystem includes a forward-looking infrared imaging system and a laser range finder. The second subsystem includes a fire control system. The fire control system includes an optional inertial measurement unit and predicts target location. The projectile is mounted in a missile launched from a platform such as a vehicle. After an initial burn, the missile launches the projectile while in flight to the target. The missile is implemented with a rocket with a guidance system and a propulsion system. In accordance with the present teachings, the guidance system includes a transceiver system mounted on the projectile. The transceiver system includes a low-power continuous wave, millimeter wavelength wave emitter. A system is included at the launch platform for communicating with the projectile. The platform system sends a blinking command to the projectile and measures the round trip delay thereof to ascertain the range of the projectile. Velocity is determined by conventional Doppler techniques or differentiation. Azimuth and elevation are then determined by a monopulse antenna on the launch platform. As a consequence, the platform ascertains the location of the projectile and the impact point thereof. The platform generates a command to the projectile which is received by the projectile and used to actuate control surfaces to adjust the trajectory and impact point thereof as necessary.

Non-Rocket Missile Rope Launcher

Abstract: The method, installation, and estimation for delivering payload and missiles into outer space are presented. This method uses, in general, the engines and straight or closed-loop cables disposed on a planet surface. The installation consists of a space apparatus, power drive stations located along trajectory of the apparatus, the cables connected to the apparatus and to the power stations, a system for suspending the cable, and disconnected device. The drive stations accelerate the apparatus up to hypersonic speed. The estimations and computations show the possibility of making these projects a reality in a short period of time (see attached project: launcher for missiles and loads). The launch will be very cheap $1-$2 per LB. We need only light strong cable, which can be made from artificial fibers, whiskers, nanotubes, which exist in industry and scientific laboratories.

Computation of stability derivatives of spinning missiles using unstructured cartesian meshes

Abstract: Advances and mo difications to increase the versatility of the SY -TIGER CFD code to compute aerodynamics for a wider variety of flight configurations are presented. Modifications were made to compute the time -dependent aerodynamic performance of spinning missiles. A proce dure for generating a database of aerodynamic stability derivatives for spinning missiles is described. The modified code was applied to two generic spinning missile configurations with excellent comparison to available data. Nomenclature

Low cost, high G, micro electro-mechanical systems (MEMS), inertial measurements unit (IMU) program

Abstract: Precision guided munitions (PGMs) are critical to the Maneuver Battalion Commander's success on future rapidly deployed battlefields. These PGMs will provide an increase in lethality, significantly improve survivability, reduce collateral damage, minimize non-combatant casualties, and decrease the logistics burden or increase the number of kills from the standard logistics load. PGMs all require inertial measurement sensors embodied in an IMU. Until now, they have been large, expensive, and could not readily survive the high G launch environments. MEMS technology provides inherent cost savings and size reduction and is ideal for application to navigation and control systems for small missiles and munitions. Using MEMS technology, gyroscopes, accelerometers and control electronics can readily be integrated to form a tightly packaged, low-cost, extremely small, high performance IMU suitable for munition, missile, and personnel guidance as well as other applications. This paper describes the current Army development underway and its partnership with industry to achieve the necessary requirements. The program goal is to survive a 20,000 g gun launch and meet a 1/spl deg//hr, 1/2 milli-g performance capability. The MEMS IMUs will significantly reduce the cost of precision-delivered missiles and munitions, as well as expand precision delivery capability to artillery ammunitions, and thus reduce the number of required rounds by more than 30% while meeting roughly 90% of the tactical weapons fleet navigational requirements.

Multicolor and dual-band IR camera for missile warning and automatic target recognition

Abstract: For applications like missile warning and automatic target recognition, AIM is presently launching its new 3rd generation high speed dual-color module. The focal plane array (FPA) is a mercury cadmium telluride (MCT) 192x192 56micrometers pitch device in a dual-color mid wave (MWIR) design. The module provides spectral selection with temporal and spatial coincidence for both colors using a new AIM proprietary technology. The spectral bands presently selected are 3.4-4 and 4.2-5micrometers with a full frame rate of 870Hz. Prior to the new devices, a sequential multicolor MCT camera with broadband detector and spectral selection using a rotating filter wheel was developed and evaluated. Results are shown to demonstrate the capabilities of spectral selective detection specifically for clutter and false alarm suppression in missile warning applications. A new algorithm was developed to allow highly sensitive detection of missile plumes without any need for non-uniformity correction for long-term stable operation and maximum dynamic range. An outlook is given on new activities at AIM on dual-band devices. The dual-band approach combining mid wave (MWIR) and long wave (LWIR) detection is specifically useful in automatic target recognition. The application, existing devices and the design goal of the new dual-band device are discussed together with experimental results.

Anti-tank guided missile weapon

Abstract: An anti-tank guided missile (ATGM) weapon system with an overhead mounted, electrically driven, remote controlled weapon station that supports a tube-launched optically-tracked wire-guided (TOW) missile launcher and a machine gun, typically the caliber .50 M2, on a single traversing and elevating platform. Above-deck assemblies include the TOW and gun cradle, a dual pod missile launcher, the Improved Target Acquisition System (ITAS), target acquisition subsystem (TAS), elevation and traverse motors and gear transmissions and drive electronics, and an ammunition case. Below-deck assemblies include the ATGM weapon system control handles, biocular display, control panel, ITAS fire control system (FCS), ITAS battery power source (BPS), slip-ring, and gunner's seat. Electrical cables connecting the two assemblies penetrate the vehicle deck directly below the weapon System.

A methodology for missile countermeasures optimization under uncertainty

Abstract: The missile countermeasures optimization problem is a complex strategy optimization problem that combines aircraft maneuvers with additional countermeasures in an attempt to survive attack from a single surface-launched, anti-aircraft missile. Classic solutions require the evading aircraft to execute specific sequences of maneuvers at precise distances from the pursuing missile and do not effectively account for uncertainty about the type and/or current state of the missile. This paper defines a new methodology for solving the missile countermeasures optimization problem under conditions of uncertainty. The resulting genetic programming system evolves programs that combine maneuvers with such countermeasures as chaff, flares, and jamming to optimize aircraft survivability. This methodology may be generalized to solve strategy optimization problems for intelligent, autonomous agents operating under conditions of uncertainty.