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Showing papers by "Saab AB published in 2004"


Journal ArticleDOI
TL;DR: In this article, the effects of spanwise distribution on the aircraft aerodynamic efficiency were studied through an inverse twist design approach, combining both a low fidelity panel method and a high-fidelity Reynolds-averaged Navier-Stokes solution method.

210 citations


Journal ArticleDOI
TL;DR: In this paper, a gradient method for optimization of shape and materials for radar cross section (RCS) reduction is derived from Maxwell's equations, which uses the adjoint problem and finds the derivatives of the RCS with respect to all design parameters from a single solution of the scattering problem.
Abstract: A gradient method for optimization of shape and materials for radar cross section (RCS) reduction is derived from Maxwell's equations. The method uses the adjoint problem and finds the derivatives of the RCS with respect to all design parameters from a single solution of the scattering problem. The method is tested in two-dimensional test problems to minimize the RCS in specified angular intervals at a single frequency, and finds configurations with strongly reduced RCS in a small number of iterations. In the absence of other constraints, the optimal shapes of perfectly electrically conducting (PEC) scatterers have sharp corners pointing in the directions where the RCS is minimized and shapes optimized at a single or small number of frequencies exhibit corrugations with about half the wavelength of the incident wave. The corrugations can be suppressed by means of penalty functions, and this gives only moderate increases of the RCS. After such regularization, the optimal shapes agree well with expectations from geometrical optics; they have almost flat surfaces whose normals lie outside the intervals chosen for RCS optimization, and sharp edges at locations where the surface normal points into the intervals in which the RCS is minimized. Shape optimization of PEC wing profiles aiming at both good aerodynamical properties and low RCS show give conflicting requirements on the shape. Copyright © 2004 John Wiley & Sons, Ltd.

38 citations


Patent
Eriksson Jan-Erik1
03 Jul 2004
TL;DR: In this article, a system for in-flight control of an aerial vehicle including an on-board flight control system, a remote control station and a read-only digital representation of a subset of the airspace is described.
Abstract: A system for in-flight control of an aerial vehicle ( 2 ) including an on-board flight control system ( 5 ), a remote control station ( 4 ) and a read-only digital representation of a subset of the airspace. The flight control system ( 5 ) and the remote control station ( 4 ) each comprises the digital representation. The digital representation comprises data for an allowed airspace ( 3 ) and at least one mission airspace ( 11 ) within the allowed airspace ( 3 ). The flight control system ( 5 ) is arranged to operate the aerial vehicle ( 2 ) within the mission airspace ( 11 ) under control of the remote control station ( 4 ).

35 citations


Journal ArticleDOI
TL;DR: In this article, the derivatives of radar cross sections (RCS) with respect to scatterer shape in two and three dimensions are derived from a single solution of the scattering problem, and gradient-based optimizations converge with a small number of iterations to shapes with strongly reduced RCS in specified angular intervals.
Abstract: Analytical expressions are derived for the derivatives of radar cross sections (RCS) with respect to scatterer shape in two and three dimensions. Using the adjoint formulation, the derivatives of the RCS, with respect to an arbitrary number of design parameters, are found from a single solution of the scattering problem. In two dimensions, gradient-based optimizations converge with a small number of iterations to shapes with strongly reduced RCS in specified angular intervals. The optimal shapes have sharp corners in directions where the RCS is minimized and exhibit corrugations, which can be suppressed by use of penalty functions. The method is also applied to RCS optimization using dielectric and magnetic absorbing materials.

28 citations


Patent
31 Aug 2004
TL;DR: In this article, a collision handler is adapted to receive information about commanded maneuvers of own aircraft, and to detect an approaching collision based on own aircraft maneuvers commanded during a time period between sending the computed own fly away path to the other aircraft and detecting the approaching collision.
Abstract: A system and a method for automatically avoiding collisions between own aircraft and other aircraft. The system comprises a computing unit (10), computing an fly away path for own aircraft, a sender (12), sending the computed own fly away path to the other aircraft, a receiver (14), receiving fly away paths from the other aircraft, and a collision handler (18), detecting an approaching collision bases on the own fly away path and the fly away paths received from the other aircraft, and activating a fly away maneuver upon detecting an approaching collision. The collision handler is adapted to receive information about commanded maneuvers of own aircraft, and to detect an approaching collision based on own aircraft maneuvers commanded during a time period between sending the computed own fly away path to the other aircraft and detecting the approaching collision.

26 citations


Journal IssueDOI
TL;DR: An airborne reconfigurable measurement system being developed at Swedish Defence Research Agency (FOI), Sensor Technology, Sweden is described, and an image processing oriented sensor management architecture for UAV (unmanned aerial vehicles) IRsEO-surveillance is presented.
Abstract: This paper describes an airborne reconfigurable measurement system being developed at Swedish Defence Research Agency (FOI), Sensor Technology, Sweden. An image processing oriented sensor management architecture for UAV (unmanned aerial vehicles) IRsEO-surveillance is presented. Some preliminary results of navigation aided image processing in UAV applications are demonstrated, such as SLAM (simultaneous localization and mapping), structure from motion and geolocation, target tracking, and detection of moving objects. The design goal of the measurement system is to emulate a UAV-mounted sensor gimbal using a stand-alone system. The minimal configuration of the system consists of a gyro-stabilized gimbal with IR and CCD sensors and an integrated high-performance navigation system. The navigation system combines dGPS real-time kinematics (RTK) data with data from an inertial measurement unit (IMU) mounted with reference to the optical sensors. The gimbal is to be used as an experimental georeferenced sensor platform, using a choice of carriers, to produce military relevant image sequences for studies of image processing and sensor control on moving surveillance and reconnaissance platforms. Furthermore, a high resolution synthetic environment, developed for sensor simulations in the visual and infrared wavelengths, is presented. © 2004 Wiley Periodicals, Inc.

22 citations


Patent
Kristian Lundberg1
12 Oct 2004
TL;DR: In this article, a trajectory is planned from a start node to a final node in a digital representation of the geographical region and the threat exposure for a vehicle moving along the trajectory is determined.
Abstract: The present invention relates to planning of a trajectory for minimum threat exposure in a given geographical region. A trajectory is planned from a start node to a final node in a digital representation of the geographical region. The threat exposure for a vehicle moving along the trajectory is determined. Navigation performance of the vehicle along the trajectory is evaluated. A rate of survival based on threat exposure and navigation performance along the trajectory is estimated. A new trajectory is planned from the start node to the final node until a best rate of survival is established for the planned trajectory.

19 citations


Patent
Hans Hellsten1
26 Apr 2004
TL;DR: In this paper, a filter scheme for broadcast interference cancellation that is computationally efficient and numerically robust Airborne Low Frequency Synthetic Aperture Radar (SAR) operating in the VHF and UHF bands has been shown.
Abstract: A filter scheme for broadcast interference cancellation that is computationally efficient and numerically robust Airborne Low Frequency Synthetic Aperture Radar (SAR) operating in the VHF and UHF bands has been shown. At least interference Doppler filtering or interference cancellation is utilised. The interference cancellation involves prediction of the interference for each particular reception interval of mixed interference and radar ground response. This prediction is then coherently subtracted from the incoming signal.

18 citations


Patent
Anders Hagstedt1
17 Aug 2004
TL;DR: In this article, an inertial measurement unit, a direction-sensing module and a velocity processor are used to measure a spatial velocity vector in order to make determination of a geographical position possible.
Abstract: Measurement of a spatial velocity vector in order to make determination of a geographical position possible. A spatial velocity meter includes an inertial measurement unit, a direction-sensing module and a velocity processor. The inertial measurement unit registers acceleration parameters and angular velocity parameters in three dimensions. The direction-sensing module registers a natural reference signal. The velocity processor receives the acceleration parameters, the angular velocity parameters and the natural reference signal, and based thereon, generates the spatial velocity vector.

17 citations


Patent
Ulf Bjoerkman1, Anders Holmquist1
26 Mar 2004
TL;DR: In this paper, the authors present a system consisting of a fire simulation system and at least one hit simulation system, which consists of means (2) for transmitting electromagnetic waves to simulate real ammunition from a weapon and means (21) for including information in the electromagnetic waves.
Abstract: This invention concerns a weapon effect simulation system comprising a fire simulation system and at least one hit simulation system. The fire simulation system comprises both means (2) for transmitting electromagnetic waves to simulate real ammunition from a weapon and means (21) for including information in the electromagnetic waves. The hit simulation system contains both means for receiving the transmitted electromagnetic waves and means (33) for determining, based on received electromagnetic waves, whether a target has been hit. The weapon effect simulation system is characterized in that the fire simulation system further comprises means (17) for calculating the imagined trajectory of the simulated ammunition and means (20) for determining the geographical position of the weapon, and in that the means (21) for including information in the electromagnetic waves are arranged so as to include information related to coordinates in the three-dimensional space for the calculated ammunition trajectory.

16 citations


Patent
18 Aug 2004
TL;DR: In this paper, a breathing mask with display device is presented, which is suitable for wearing when working in a smoke-filled environment, and comprises means for the provision of gas, means for removal of exhaled air, a visor that allows a wearer of the breathing mask to view directly through the visor, and an infrared camera (10), an optics unit (11) with display (15), and an electronics unit with power supply.
Abstract: The invention relates to a breathing mask with display device. The breathing mask (1) is suitable for wearing when working in a smoke-filled environment, and comprises means for the provision of gas (2), means for the removal of exhaled air (3), a visor (4) that allows a wearer (6) of the breathing mask to view directly through the visor, means for fitting the breathing mask on the wearer (8, 9), and an infrared camera (10), an optics unit (11) with display (15) and an electronics unit with power supply. According to the invention, the optics unit (11) with display (15) is arranged on the inside of the visor (4) in such way that it is adjustable by means of an adjustment mechanism (18). By means of the invention, an embodiment is achieved that is protected against dirt and condensation, with a design that is less of a load on the wearer (6) than known designs. At the same time, the invention means that many existing breathing masks can be easily upgraded with infrared image display.

Patent
15 Nov 2004
TL;DR: In this article, a transmitting unit (1) has a transmitter for transmitting signals of coded information about a position close to the unit in a space substantially unreachable by a satellite-based navigating system so as to provide a receiver arranged on a moving object present in said space with this position information for determining the position of this object.
Abstract: A transmitting unit (1) has a transmitter for transmitting signals of coded information about a position (12) close to the unit in a space substantially unreachable by a satellite-based navigating system so as to provide a receiver (22) arranged on a moving object (21) present in said space with this position information for determining the position of this object The transmitter is adapted to normally be in an inactive non-transmitting state, and the unit further comprises means adapted to detect movement of a said object within said space and activate the transmitter to transmit said si gnals only when a movement of a said object in said space is detected

Patent
Bergkvist Bengt1
30 Apr 2004
TL;DR: In this article, the Doppler filter is arranged to give rise to a number of independent samples from reflectors within the radar's unambiguous range, when the sad independent samples exceed the small number of samples, the radar approves the ambiguous echo.
Abstract: A radar is arranged to transmit electromagnetic energy in pulse repetition intervals and to receive reflections or echoes from objects in range gates intended for the purpose, which range gates are provided with Doppler filters. The radar is arranged to approve ambiguous echoes that are desirable and to suppress ambiguous echoes that are of no interest or that interfere with the display function of the radar. The radar works with a frequency that varies according to a staggered or wobbling pattern. The respective ambiguous echoes produce only one pulse in the respective range gates concerned, within a predetermined number of periods. The respective Doppler filter concerned is arranged to work with an impulse function response that only consists of a small number of samples. The Doppler filter is also arranged, during the predetermined number of periods, to give rise to a number of independent samples from reflectors within the radar's unambiguous range. When the sad independent samples exceed the small number of samples, the radar approves the ambiguous echo. Otherwise, it is suppressed. In this way, ambiguous echoes are prevented from interfering with the reception or display of the echoes on the display screen. The suppression of asynchronous interferences, for example pulses from other radar stations, can also be made easier in a simple way.

Proceedings ArticleDOI
10 May 2004
TL;DR: In this paper, a perforate acoustic liners are used in hot areas of aero-engines to deal with the flow and sound pressure level of the aero engine.
Abstract: Conventional perforate acoustic liners are presently used in hot areas of aero-engines. The acoustic characteristics of these liners are extremely sensitive to flow and sound pressure level. Curren ...

Patent
Hagelin Hans-Ove1
26 Mar 2004
TL;DR: In this article, the authors present a method of establishing rules for a specific device which is intended to be able to be used for generating decision support for decisions which determine the behavior of an entity and/or for controlling the behaviour of the entity.
Abstract: The invention concerns a method of establishing rules ( 14 ) for a specific device which is intended to be able to be used for generating decision support for decisions which determine the behavior of an entity ( 44 ) and/or for controlling the behavior of an entity ( 44 ). The device is, inter alia, arranged to present a decision support window which comprises at least one area ( 56 ) which represents a state ( 30 ), wherein this area ( 56 ) comprises names which identify different rules ( 14 ) which form part of the state ( 30 ). The method according to the invention comprises the steps that the device is run in a real or simulated version of said entity ( 44 ), that said decision support window is presented to a user, that the user makes decisions by inputting instructions, that the decisions which have been made by the user are analysed, and that the rules ( 14 ) for which the user has made decisions are determined or modified in accordance with the analysis which has been carried out.

Patent
31 Aug 2004
TL;DR: In this article, a station for assisting the control of an aircraft includes warning means (5) adapted to deliver an alert for avoiding a later collision when there is a risk that the predicted flight trajectory of the aircraft crosses any predicted flight path of another aircraft.
Abstract: A station for assisting the control of an aircraft includes warning means (5) adapted to deliver an alert for avoiding a later collision when there is a risk that the predicted flight trajectory of the aircraft crosses any predicted flight path of another aircraft An arrangement (4) is adapted to determine whether the aircraft carrying said station is within an airspace volume with defined geometrical dimensions and time of appearance and disappearance or not and make the function of the warning means dependent upon this comparison by, when located in said airspace volume, deactivating said warning means with respect to other aircraft of a predefined identity, and when not located in said airspace volume, activate or keep the function of said warning means activated with respect to aircraft of said predefined identity

Patent
02 Jun 2004
TL;DR: In this paper, an arrangement for a weapon comprising a countermass (6) for reducing the pressure around the weapon is described. But the countermass is enclosed in a counter mass container (5) which can be opened at both ends (8, 28).
Abstract: The invention relates to an arrangement for a weapon comprising a countermass (6) for reducing the pressure around the weapon. The countermass (6) is enclosed in a countermass container (5) which can be opened at both ends (8, 28). The invention aims to bring about a symmetrical opening with favourable recoil in a better way than in previous constructions. This is achieved by the countermass comprising means which can bind and retain the liquid symmetrically in a desired geometry over the cross section of the barrel and the cross section of any following expansion part.

Patent
23 Sep 2004
TL;DR: In this paper, a method for training behavior during a nuclear, biological or chemical warfare attack, including a number of players, is presented, which includes determining exposure to a simulated nuclear or chemical attack for each player, providing a signal indicating said exposure in at least one alarm simulator unit, and generating an audio/visible alarm signal.
Abstract: The present invention relates to a method for training behavior during a nuclear, biological or chemical warfare attack, including a number of players. The method includes determining exposure to a simulated nuclear, biological or chemical attack for each player; providing a signal indicating said exposure in at least one alarm simulator unit, said alarm simulating unit generating an audio/visible alarm signal; and establishing the effect of said exposure for each player.

Patent
Peter Isoz1
26 Mar 2004
TL;DR: In this article, the angular motion of a direct fire weapon was continuously sensed and registered using a fixed point camera. But the angular motions of the weapon or the sight of the sight were not recorded.
Abstract: The present invention relates to a device and method at a direct fire weapon comprising means (3) for continuously sensing and registering the angular motion of the weapon or weapon sight, means for detecting fire of the weapon, and processing means (4) arranged to upon detection of fire of the weapon extract data relating to the aiming behavior from the registered angular motion for a given time interval before and after firing.

Proceedings ArticleDOI
TL;DR: There is an ongoing trend in the European Military a/c industry towards cooperation between nations when purchasing and between manufacturers when developing and producing a/C as mentioned in this paper, and different manufactur...
Abstract: There is an ongoing trend in the European Military a/c industry towards cooperation between nations when purchasing and between manufacturers when developing and producing a/c. Different manufactur ...

Patent
30 Sep 2004
TL;DR: In this article, a liquid cooling medium is applied to a control unit in an unmanned flying vehicle (UAV) when the temperature of the electronic components exceeds a predetermined level, in order to spray them directly upon the desired level of cooling.
Abstract: A device for cooling electronic components (8) of a control unit in an unmanned flying vehicle comprises a container (12) containing a liquid cooling medium, means (10) adapted to sense the temperature of said electronic components during the flight of said vehicle and means (13) adapted to be controlled by said temperature sensing means to spray said liquid cooling medium directly upon said electronic components when the temperature thereof exceeds a predetermined level.

Patent
Adam Tengblad1
02 Oct 2004
TL;DR: In this article, a simulation system comprising at least one virtual projectile/missile firing device having movable directing means to direct a virtual projectile towards a target and determine the position of said virtual projectile and the target is presented.
Abstract: Simulation system comprising at least one virtual projectile/missile firing device ( 1 ) having movable directing means ( 3 ) to direct a virtual projectile/missile towards a target ( 2 ) and means to determine the position of said at least one virtual projectile/missile firing device and the target whereby the simulation system comprises means ( 4 ) to capture at least one image of the target scene in front of the directing means ( 3 ) and means to process the, or each, image so as to determine the orientation of the directing means ( 3 ).

Patent
13 Feb 2004
TL;DR: In this paper, a method for the fabrication of a former for composite articles is described, which is characterized by the following steps: forming a wetted water-soluble fiber composite on a master tool such that the fiber composite material lies against a surface area of the master tool.
Abstract: The present invention relates to a method for the fabrication of a former for manufacture of composite articles. The method is characterized by the following steps: forming a wetted water-soluble fiber composite on a master tool such that the fiber composite material lies against a surface area of the master tool, allowing the water-soluble fiber composite to dry on the master tool and removing the dry water-soluble fiber composite from the master tool, wherein the dry fiber composite forms the walls of the thus fabricated former. The invention also relates to the manufacture of articles using said former

Patent
Emricson Ingemar1, Jonas Malm1
18 May 2004
TL;DR: In this paper, a device and method for a protective mask comprising means (3) for detecting that a protective-mask user is breathing through the breathing filter of the mask is described.
Abstract: The present invention concerns a device and method for a protective mask comprising means (3) for detecting that a protective-mask user is breathing through the breathing filter of the protective mask. The invention is characterized in that the means for detecting protective-mask use are arranged to sense the underpressure that arises in the protective mask during inhalation.

Patent
31 Aug 2004
TL;DR: In this paper, the authors proposed a TDMA protocol where the data is transmitted in time slots organized in frames of a repeating frame structure and a link address associated with at least one time slot, and the stations select link addresses for transmission of data according to a self-organizing transmission algorithm.
Abstract: The invention relates to wireless communication systems wherein services involving two or more stations in the system may be activated automatically. Data is communicated between airborne stations (A,B) according to a TDMA protocol, where the data is transmitted in time slots organized in frames of a repeating frame structure. A link address is associated with at least one time slot, and the stations select link addresses for transmission of data according to a self-organizing transmission algorithm. Each station (A,B) broadcasts data messages of a first type (D 1 ) at a first repetition rate and receives such corresponding messages from the other stations (A,B). At least based on the received data messages of the first type (D 1 ), each station determines whether a service activation criterion is fulfilled with respect to at least one other station (A,B), for example by the other station being located within a limit distance (r A ). If the service activation criterion is fulfilled, the station (A,B) starts to transmit data messages of a second type (D 2 ), which pertain to a service that involves the station itself and the at least one other station (A,B).

Journal ArticleDOI
TL;DR: In this article, the use of the magnetic amplifier technology in designing competitive electric power supplies was discussed and used in the Swedish fighter aircraft Gripen and the Swedish Sea King helicopter, respectively.

Proceedings ArticleDOI
16 Aug 2004
TL;DR: In this paper, the problem of flight clearance of linear stability requirements in the complete flight envelope is studied using mu-analysis of linear fractional transformations description of the flight evelope.
Abstract: The problem of flight clearance of linear stability requirements in the complete flight evelope is studied. The approach is to use mu-analysis of linear fractional transformations description of th ...

Patent
28 May 2004
TL;DR: In this article, a system for determination of kinematics of a moving object is proposed, consisting of a sensor (1) producing angular data for the object at a number of observation times, a state initialization unit (7), receiving angular data from the sensor and on basis thereof determining a first kinematic state of the object, and a tracking filter (11) having a prediction unit, arranged to determine a predicted Kinematics state of an object on bases of a Kinematic model.
Abstract: A system for determination of kinematics of a moving object comprising: a sensor (1) producing angular data for the object at a number of observation times, a state initialization unit (7), receiving angular data from the sensor and on basis thereof determining a first kinematic state of the object, and a tracking filter (11) having a prediction unit, arranged to determine a predicted kinematics state of the object on bases of a kinematic model of the object, wherein the kinematic model comprises a guidance law locked on a known position, and at least one previously determined kinematic state of the object, and a state updating unit, receiving angular data from the sensor and the predicted kinematic state of the object, and on basis thereof determining an updated kinematic state of the object.

Patent
Christer Regebro1
20 Oct 2004
TL;DR: In this paper, the authors present a method and a device by means of which it has been made possible, without gas discharge to the surrounding environment, to accelerate the speed of a powder-gas-driven projectile from zero to a speed which gives the projectile free-flying characteristics.
Abstract: The present invention relates to a method and a device by means of which it has been made possible, without gas discharge to the surrounding environment, to accelerate the speed of a powder-gas-driven projectile from zero to a speed which gives the projectile free-flying characteristics. According to the invention, this has been made possible by utilizing at least some of the expansion force from the propellant powder charge, which discharges gas when it is initiated, for, by a displaceable piston, driving a countermass out of the rear part of the projectile in the direction opposite to the desired flying direction of the projectile.

Patent
Ulf Björkman1, Anders Holmquist1
07 Sep 2004
TL;DR: In this article, a simulation system for use in military exercise of combat in an area having at least one building has a transmitter (5) arranged on a firearm for simulating firing of a shot and a detecting means (7) to be arranged on the body of a soldier.
Abstract: A simulation system for use in military exercise of combat in an area having at least one building has a transmitter (5) arranged on a firearm (4) for simulating firing of a shot and a detecting means (7) to be arranged on the body of a soldier. Sensors (6, 8) are adapted to sense whether said transmitter and said detecting means are located indoors or outdoors. The detecting means is designed to discriminate between normal power signals fired from outdoors and indoors, whereas the transmitter is adapted to emit signals of normal power when located outdoors and signal of normal power as well as a substantially lower power when located indoors.