Saab AB

About: Saab AB is a company organization based out in Thun, Switzerland. It is known for research contribution in the topics: Antenna (radio) & Signal. The organization has 862 authors who have published 928 publications receiving 8807 citations. The organization is also known as: Saab AB & Svenska Aeroplan AB.

Standby attitude estimation

Abstract: In most military aircraft an inertial navigation system (INS) is the main source for attitude and heading data. Aircraft attitude and heading are important quantities, and in the case of a failure in the INS, backup values are needed. We here present how these can be calculated using other sensors in the aircraft. In order to determine attitude and heading with respect to a reference coordinate system, the same quantities in both the aircraft body coordinates as well as in the reference coordinate system are needed. These can then be used to determine the rotation from reference to body coordinates and thus the attitude and heading of the aircraft. We show how data from various sensors in the Saab Gripen aircraft, can be used to generate quantities exhibiting such relations. These relations are analyzed using recorded flight data. Using vector relations the QUEST algorithm yields a least squares fit of the quaternion of rotation from reference to body coordinates. We show here an alternative and simpler approach to such an algorithm in quaternion space. The REQUEST algorithm is an extension to the QUEST algorithm that processes measurements recursively. In the REQUEST algorithm angular velocities can also be used between measurements to update the quaternion of rotation. We extend our alternate approach in a similar way, but we also solve the case were additional states besides the quaternion rotation are introduced. The angular velocities used in a system of this type are often of poor quality, and states representing e.g. bias can thus be introduced.

Calculating time to go and size of an object based on scale correlation between images from an electro optical sensor

Abstract: A method and a system for calculating a time to go value between a vehicle and an intruding object. A first image of the intruding object at a first point of time retrieved. A second image of the intruding object at a second point of time is retrieved. The first image and the second image are filtered so that the first image and the second image become independent of absolute signal energy and so that edges become enhanced. An X fractional pixel position and a Y fractional pixel position are set to zero. The X fractional pixel position denotes a horizontal displacement at sub pixel level and the Y fractional pixel position denotes a vertical displacement at sub pixel level. A scale factor is selected. The second image is scaled with the scale factor and resampled to the X fractional pixel position and the Y fractional pixel position, which results in a resampled scaled image. Correlation values, are calculated between the first image and the resampled scaled image for different horizontal displacements at pixel level and different vertical displacements at pixel level for the resampled scaled image. A maximum correlation value at a subpixel level is found based on the correlation values. The X fractional pixel position and the Y fractional pixel position are also updated. j is set to j=j+1 and scaling of the second image, calculation of correlation values, finding the maximum correlation value and setting of j to j=j+1 are repeated a predetermined number of times. i is set to i=i+1 and selecting the scale factor, scaling of the second image, calculation of correlation values, finding the maximum correlation value, setting of j to j=j+1, and setting of i to i=i+1 are repeated a predetermined number of times. A largest maximum correlation value is found among the maximum correlation values and the scale factor associated with the largest maximum correlation value. The time to go is calculated based on the scale factor.

The EMFIS Model — Enable More Frequent Integration of Software

Abstract: The EMFIS model allows companies to explicate a representation of the organization's current situation regarding continuous integration impediments, and visualizes what the organization must focus on in order to enable more frequent integration of software. The model is used to perform an assessment of twelve factors, where the ratings from participants representing the developers are summarized separately from ratings from participants representing the enablers (responsible for processes, development tools, test environments etc.). The EMFIS model is based on semi-structured interviews with 20 developers from two companies which develop large-scale software systems, and a literature review that included 74 research papers and four books. The model has been validated in workshops and interviews, which in total included 28 individuals in five different companies. The model was well received during the validation, and was appreciated for its simplicity and its ability to show differences in rating between developers and enablers.

Compression moulding method and device for making preforms for composite structures of an aircraft

Abstract: The present invention relates to a forming device (1) and a method of manufacture of a fillet (17) of plastic for aircraft assemblies or the like, said fillet (17) having a predetermined profile (9) for filling a cavity (61) of a structural element (59), the fillet (17) being formed using a forming means (29) of a forming device (1). The method comprises the steps of applying at least one blank of a base material (15) of plastic between at least two opposed press beds (5) of the forming means (29) and at least one of said press beds (5) comprising elongated grooves (7); moving at least one press bed (5) towards the other press bed, until the press beds (5) are in position for completed compression of the fillet (17), wherein each groove (7) for forming of the fillet (17) generates a fillet (17) in correspondence with said pre-determined profile (9); separating the press beds (5) from each other for releasing the formed fillets (17); removing the formed fillets (17) from the forming means (29); and applying the formed fillets (17) in the cavity (61).

Device and method for weapon sight

Abstract: This invention concerns a device for a weapon sight. The device includes a deflecting element ( 15 ) disposed in an optical path through the sight and comprising an optical wedge ( 17 ), and means ( 16 ) arranged to control the positional setting of the optical wedge to produce a randomly altered sight image in the sight. The device is characterized in that the control means ( 16 ) are arranged to produce, before firing, the altered sight image and, during firing, to guide the wedge or wedges to a reference position in which the sight image is unaltered. The invention also concerns a method for optically simulating recoil in a weapon with a sight.