Showing papers on "Missile published in 1992"

Dynamic scheduling of modern-robust-control autopilot designs for missiles

Abstract: The dynamic scheduling of multiple linear-time-invariant (LTI) controllers, designed using H/sub infinity // mu techniques, for systems with widely varying plant dynamics is examined. The observer/full-state feedback structure of the LTI H/sub infinity / controller is extended to accommodate the time-varying, nonlinear dynamics problem. A procedure for handling the variations that occur between fixed operating points, in the two-Riccati equation solutions, is proposed. An example missile control problem that contains realistic and necessary performance goals and robustness constraints is included to demonstrate the viability of the approach. >

Laser anti-missle defense system

Abstract: An attack missile is disabled during its travel through atmospheric regions, enroute to a selected target, by directing, with the aid of a pointer tracker, a first continuous wave laser beam produced by a chemical laser from a first location through the atmosphere onto a given area of the missile to release radiant heating energy in the given area; and simultaneously directing, with the aid of another pointer tracker, a second continuous wave laser beam produced by a second chemical laser from a second location through the atmosphere onto the same given area of the missile to release radiant heating energy in the given area. The beams are arranged so that there is no material overlap between the laser beams enroute to the missile. Over a short duration the laser beams release a combined radiant heating energy on the given area of the missile sufficient in amount to at least damage a portion of the given area of said missile, resulting in the missile's destruction.

Aeroelastic stability of slender, spinning missiles

Abstract: The coupled equations of motion that govern the static and dynamic aeroelastic stability of spinning, flexible missiles are derived. A Lagrangian approach is employed which results in nonlinear coupling between the elastic deflections and the rigid-body motion parameters. Various approximations inherent in reducing the equations to a linear set are indicated. Firstorder aerodynamics are formulated for application to a hypersonic missile. Some numerical examples are given that reveal a destabilizing influence of structural damping at certain roll rates for a particular missile configuration.

Integrated Estimation, Guidance, and Control System Design Using Game Theoretic Approach

Abstract: In order to produce a robust coupling between the guidance system and autopilot and improve the target intercept capability, the game theoretic approach is applied to the derivation of an integrated estimation, guidance and control scheme for missile intercept problem. The objective of fomulating the game problem is to find a contoller, combining the guidance law and autopilot controller, which minimizes the final miss distance and the control energy in the worst case of target maneuver and the worst case of measurement uncertainty, and to find an estimator that provides feedback information for autopilot implementation and target tracking information for guidance processing. The controller and estimator obtained from the game theoretic approach form a linear n-dimensional compensator and the controller is solved in closed-form. In a full information and nonmaneuver case, the solution recovers the integrated guidance and control (IGC) law designed by using the linear quadratic optimal approach as presented in [Lin and Yueh, 1984(a)-(c); Yueh and Lin, 1985].

A Linear Parameter Varying Approach to Gain Scheduled Missile Autopilot Design

Abstract: This paper presents a gain-scheduled design for a missile longitudinal autopilot. The gain-scheduled design is novel in that it does not involve linearizations about trim conditions of the missile dynamics. Rather, the missile dynamics are brought to a quasi-linear parameter varying (LPV) form via a state transformation. An LPV system is defined as a linear system whose dynamics depend on an exogenous variable whose values are unknown a priori but can be measured upon system operation. In this case, the variable is the angle-of-attack. This is actually an endogenous variable, hence the expression "quasi-LPV". Once in a quasi-LPV form, a robust controller using ?-synthesis is designed to achieve normal acceleration control via fin deflections. The final design is an inner/outer loop structure, with angle-of-attack control being the inner-loop, and normal-acceleration control being the outer loop.

Robust feedback linearization approach to autopilot design

Abstract: The feasibility of autopilot design for highly maneuverable bank-to-turn (BTT) missiles using feedback-linearization-based approaches is investigated. Two schemes, namely, feedback linearization and robust feedback linearization, are designed and compared based on a full-scale six-degree-of-freedom HAVE DASH II terminal homing missile model. Although the feedback linearization controller is quite satisfactory in general, a sizable coupling between the longitudinal motion and lateral motion for large maneuvers is observed. This is attributed to the uncertainties arising from the approximation of the aerocoefficients and model simplification. The second scheme, which adds a robust outer-loop design based on Lyapunov's second method to the first scheme in order to account for this uncertainty, shows a significant improvement over the first scheme. >

Broadband conformal inclined slotline antenna array

Abstract: A missile guidance antenna that is conformal to the missile surface, dual-polarized and broadband. Slotline notch array elements (30, 52) are inclined toward boresight for both the E and H-planes. This inclination directs a greater portion of the energy toward the front of the missile. The additional energy directed forward reduces the nullifying effects of the metallic skin on the tangential E-field and enhances the performance of the other polarization. The slotline elements (30, 52) can be packed with spacing close enough to allow for electronic beam steering without creating grating lobes in the field at the highest frequency of operation.

Design of robust, time-varying controllers for missile autopilots

Abstract: The design of a longitudinal gain-scheduled autopilot for a tail-controlled missile using mu -synthesis control design techniques is discussed. The goal is to design a single controller to track commanded acceleration maneuvers with a steady state error of 0.5%, a time constant of less than 0.2 s, a step response overshoot of less than 10% and a maximum tail-deflection rate of 25 degrees/s/g. The controller is to provide robust performance over a range of +or-20 degrees angle-of-attack and missile speeds between Mach 2 and 4. The controller must avoid saturating the tail-deflection actuator rate capabilities and destabilizing unmodeled high frequency flexible body modes of the missile. >

ALinear Parameter Varying Approach toGainScheduled Missile Autopilot Design

Abstract: This paper presents a gain-scheduled design for a missile longitudinal autopilot. Thegain-scheduled design is novel inthat itdoes notinvolve linearizations about trim conditions ofthemissile dynamics. Rather, themissile dynamics arebrought toa quasi-linear parameter varying(LPV)formviaa statetransformation. AnLPV systemisdefined asalinear systemwhose dynamics depend on anexogenousvariable whose valuesareunknown apriori butcanbemeasured upon systemoperation. In this case,thevariable istheangle-of-attack. This isactually anendogenous variable, hence the expression "quasiLPV".Onceina quasi-LPV form, a robust controller using p-synthesis isdesigned toachieve normal acceleration control viafindeflections. Thefinal design isan inner/outer loopstructure, withangle-of-attack control being theinner-loop, andnormal-acceleration control beingtheouterloop.

Technique and apparatus for rearward launch of a missile

Abstract: A technique and apparatus for rearward launch of a missile. The inventive apparatus (10) includes a launch tube (12) in which the missile (14) is mounted with the forward end of the missile being mounted at the forward end (16) of the tube. The rearward end of the launch tube is sealed with a break-away material (18) prior to expulsion of the missile (14). An expulsion mechanism expels the missile in a rearward direction from the launch tube. The expulsion mechanism includes an airbag (20) and a pressurization mechanism (30). The airbag (20) includes a bra (22) for maintaining the orientation of the missile (14) during the expulsion thereof. The airbag (20) also includes a metallized enclosure (24) for sealing the launch tube (14) after the expulsion of the missile (14).

Missile surveillance method and apparatus

Abstract: Multispectral signature analysis techniques are used to reliably separate a missile electro-optical signal from a background. The system provides higher reliability and reduced complexity when compared to conventional approaches.

Application of Integrated Guidance and Control Schemes to a Precision Guided Missile

Abstract: Three optimal integrated guidance and control (IGC) laws for a tactical missile are developed. The three IGC design models include planar intercept kinematics and missile longitudinal dynamics in one mathematical framework. A target acceleration model and missile radome error compensation scheme are inluded in the state formulations. An optimality criterion which asymptotically imposes an infinite penalty on miss distance and angle-of-attack in the endgame as time-to-intercept goes to zero is minimied. Using reasonable approximations, an analytic solution is derived which can be easily implemented as an endgame guidance law/autopilot in current missile flight computers. Nonlinear six degree-of-freedom simulation results will be presented at the session to demonstrate the performance of these three algorithms.

Distributed weapon launch system

Abstract: A battery of dispersed missile launch stations (1-4) are linked to a central communications station (5) which assigns different targets to respective launch stations. The communications station ensures that only one launch station engages each target.

Tactical missile aerodynamics : general topics

Abstract: This two-volume set includes discussions of the physics of the fluid mechanics phenomena associated with tactical missile flight and the full range of prediction methods required to analyze current and future missiles. It's a valuable resource for missile aerodynamicists, designers, and researchers.

Game Optimal Guidance Law Synthesis for Short Range Missiles

Abstract: A horizontal pursuit-evasion game of kind in the atmosphere between a coasting pursuer with a final velocity constraint and a maneuvering evader of constant speed is considered. For this model, which is suitable to describe short range missile engagements, the adjoint equations can be integrated analytically. This allows us to determine the optimal strategies of the players on the boundary of the capture set, called the barrier, as a function of the current and final values of the state variables. The main effect of the pursuer's final velocity constraint, an important realistic parameter, neglected in previous studies, is a substantial reduction of the capture zone. However, based on this game solution, a feedback guidance law, suitable for real-time implementation, can be synthesized and compared to other guidance laws. The results show that the corresponding capture set is much larger than the firing envelope of a similar missile guided by proportional navigation with the same final velocity constraint.

Tactical Missile Aerodynamics: Prediction Methodology

Abstract: Tactical Missile Drag Drag Prediction Methods for Axisymmetric Missile Bodies Introduction to the Aerodynamic Heating Analysis of Supersonic Missiles The Component Build-Up Method for Engineering Analysis of Missiles at Low-to-High Angles of Attack Analysis Methods and Experiments for Missiles with Noncircular Fuselages Vortex Cloud Model for Body Vortex Shedding and Tracking Panelling Methods with Vorticity Effects and Corrections for Nonlinear Compressibility Supersonic Full-Potential Methods for Missile Body Analysis Space Marching Euler Solvers Time-Asymptotic Euler/Navier-Stokes Methods for Subsonic/Transonic Flows Three-Dimensional Boundary Layers on Missiles Navier-Stokes Analyses of Flows over Slender Airframes Exhaust Plumes and Their Interaction with Missile Airframes - a New Viewpoint

Missile canister and method of fabrication

Abstract: A missile canister (110) for storing, transporting and launching missiles includes inner (114) and outer (112) skins and a compression resistant honeycomb type material (116) between the skins. An alternative embodiment on the missile canister has an epoxy syntactic foam material between the skins of the cells which are attached one to another by threaded fasteners (442) which cooperate with tapped holes (440) in the cell walls.

Design of autopilots for high performance missiles.

Abstract: A novel control algorithm involving a robust inverse dynamics estimation (RIDE) is presented. It is shown how the control algorithm can be used in conjunction with a new safe criterion to result in the optimal and safe control algorithm (OSCA). The OSCA control algorithm is applied to the control of a high performance missile, where it is shown to provide excellent performance in terms of tight non-interacting and safe control in the presence of actuator saturation.

Seeker head assembly in a guided missile

Abstract: In a seeker head assembly in a guided missile, particularly a high-speed guided missile, the seeker head (22) is covered by a dome (28) which is rotatably mounted in the structure and is rotated. The dome (28) is circumferentially surrounded by the structure (10) of the guided missile except for a window section (14). A coolant is supplied to an interspace (46) formed between dome (28) and structure (10) of the guided missile.

Component build-up method for engineering analysis of missiles at low-to-high angles of attack

Abstract: Methods are presented for estimating the component build-up terms, with the exception of zero-lift drag, for missile airframes in steady flow and at arbitrary angles of attack and bank. The underlying and unifying bases of all these efforts are slender-body theory and its nonlinear extensions through the equivalent angle-of-attack concept. Emphasis is placed on the forces and moments which act on each of the fins, so that control cross-coupling effects as well as longitudinal and lateral-directional effects can be determined.

Guidance and targeting for the strategic target system

Abstract: Guidance algorithms and targeting procedures for the Strategic Target System (STARS) launch vehicle are described. The STARS vehicle is a three-stage booster, based partly on retired Polaris A3 missile assets, which is intended to support development and testing of the Strategic Defense Initiative by delivering target payloads to the vicinity of the Kwajalein Atoll. STARS will be launched from the Kauai Test Facility located on Kauai, Hawaii. The STARS guidance objective is to deliver payloads to a prescribed target location with intercontinental ballistic missile re-entry conditions. The guidance problem is complicated by the fact that all three stages lack thrust termination or other velocity control mechanisms, and by range safety requirements for one or more out-of-plane turns. Mission objectives are achieved with a combination of guidance algorithms. The original Polaris guidance is used during the atmospheric ascent phase. The powered explicit guidance used by the Space Shuttle is later employed to execute an out-of-plane turn and to place the third stage as closely as possible onto the desired coast trajectory. Third-stage guidance is a modified Lambert procedure formulated to eliminate the target miss due to off-nominal ascent phase performance.

New Results in Optimal Missile Avoidance Analysis

Abstract: Optimal missile avoidance of a constant speed aircraft from a coasting missile of first-order dynamics, guided by proportional navigation is analysed in the plane. This model allows the investigation of the "missile outrunning" and "end game evasion" maneuvers in the same engagement. Three regions of different optimal avoidance strategies are identified. All strategies are compromises in satisfying different optimal evasion principles: bleeding energy from the missile and minimizing of the closing velocity (principles of "missile outrunning"), and a final maneuver of a critical duration, perpendicular to the line of sight (principles of optimal "end game evasion"). Due to the missile's aerodynamic drag, the aircraft is able to reduce missile maneuverability by an "outrunning" maneuver so that in the "end-game" a larger miss distance can be generated.

Automated gain schedules for missile autopilots using robustness theory

Abstract: Preliminary results in computer-automated missile flight control design are presented. The structured singular value mu is used to automate the calculation of gain schedules for a missile autopilot. Using mu -analysis, the approach guarantees both stability and performance robustness between the gain scheduled grid points. >

Method for selfguidance of missile towards a target by means of range measurements

Abstract: The missile (E) comprises a recognition and tracking unit (13) which receives an infrared image in order to extract from it objects having characteristics identical to predetermined targets (CB). When identification is established, the recognition and tracking unit (13) then controls the antenna control unit (14) so that the object identified is permanently in the centre of the image received. The identification unit (2) establishes the attitude (S, G) of the antenna (11) with respect to the missile (E), and the inertial reference unit (3) establishes the attitude of the missile (E) with respect to an inertial reference axis system linked to the centre of gravity of the missile so that a computer (4) calculates the azimuth angle ( alpha G) of the presumed target in the inertial axis system and deduces the distance (D) separating the missile (E) from the presumed target (CB). This distance information (D) allows a more precise authentication of the target. Additional means (5, 6) make it possible to orient the missile (E) with a view to reaching the target (CB) according to predetermined criteria, particularly by skirting round the target towards a favourable impact point on the target.

Electromagnetic sandwich esp for repulsing military attacks such as with missiles

Abstract: The electromagnetic sandwich has an acceleration device with a protective element accelerated by the acceleration device and an activation device for activating the acceleration device which pref. contains a sensor for detecting a threat/missile. The acceleration device is an electrical magnetic coil system (1) with conducting layers (2) and protection elements (3). The activation device has a capacitor which can be charged up by a power supply and which can be discharged to stimulate the magnetic coil system.

Trajectory scheduled missile autopilot design

Abstract: An alternate approach to the design of gain-scheduled controllers is given. Standard gain-scheduling typically relies on the instantaneous value of the scheduling variable to update the control gains. This approach has the drawbacks of being limited to slow transitions between operating points and requiring a number of possibly tedious point-by-point designs. The present approach is to have the controller gains dynamically evolve according to the scheduling variable's history, rather than its instantaneous value. At the cost of increased order of the controller, this approach allows rapid transitions between operating conditions and alleviates the need for several point-by-point designs. The approach is demonstrated via a stabilizing control design for a longitudinal missile model. >

Aerodynamic test and analysis of a missile configuration with curvedfins

Abstract: This paper presents the results of an investigation into the aerodynamics of generic, wrap around fin (WAF) missile configurations flying at supersonic Mach numbers (2.75 5.15). The missile configurations were designed to investigate the loss of static stability with increasing velocity and effects of fin geometry on induced roll and side moment. The subscale results are compared to state-of-the-art inviscid computational fluid dynamic (CFD) and engineering code prediclions. The results of the free flight data reduction and precictions are summarized and compared. The results of this investigation indicate that the static stability experiences a possible anomaly due to shock structure in the fin region, drag data scatter due to turbulent bursts and flow transition, classical roll and side moment behavior consistent with wrap around fin designs, and good agreement with aerodynamic orediction codes (empirical and CFD).

Deployment of a flexible beam from an oscillating base

Abstract: case when implemented judiciously. This example is an adaptive missile autopilot' where the controller measures the missile's acceleration normal to the flight path and seeks to make it follow a commanded acceleration by rotating the missile with tail-fin deflections (the control variable) to create body lift. Instead of being limited by established theory, the prior variances of the (two) unnormalized parameters, which are proportional to h and reflect variability in the flight conditions, were made as large as would empirically allow reasonable behavior at the nominal flight condition, which is Mach 2.0 at 6000 m altitude. The probing control term has little effect then but substantially improves the initial performance for the very different flight condition of Fig. 1 by causing the parameter estimates to converge more quickly to the corresponding nonzero values, which occurs because this control term reduces the uncertainties of these parameters more quickly.

Multiple missile ejection system

Abstract: A multiple missile ejection system (10) by which first and second missiles (14) and (16) are stored in a single launch tube (12) Each missile is ejected by a gas bag In a particular embodiment, two gas bags are used The first gas bag (18) is mounted between the first and second missiles (14) and (16) respectively The second gas bag (20) is mounted between the second missile (16) and an end of the launch tube When deflated, the first gas bag (18) has a longitudinal aperture (28) through the center thereof which allows for the ejection of the second missile (16) by the second gas bag (20)

Seeker head cover for guided missile

Abstract: In a seeker-head cover for covering a seeker head (22) in a guided missile, especially a high-speed guided missile, having a structurally-fixed, side window (26) by means of which the seeker head (22) is hermetically sealed from the environment, the seeker head (22) and the window (26) are for their part covered by a dome (28) which is supported and can be driven such that it can rotate. The dome (28) is surrounded by the structure (10) of the guided missile in the circumferential direction, except for a window cut-out (14) in the region of the window (26). A cooling medium can be introduced into an intermediate space (46) which is formed between the dome (28) and the structure (10) of the guided missile.