Saab Ab

Jimmy Jonsson

Per-Olof Persson

Sören Molander

Linnea Nilsson

A method for determining a direction at a position is provided. The method involves obtaining an orthorectified photo of a region of Earth's surface comprising the position, and a coordinate system for the orthorectified photo; identifying the position in the orthorectified photo; identifying a reference object in the orthorectified photo; determining a reference direction between the position and the identified reference object; capturing at least one digital photo at the position with a calibrated digital camera, wherein at least one of the at least one captured digital photo depicts the reference object; and determining the direction based on the at least one captured digital photo and the determined reference direction, wherein the determined direction is based on at least one pixel coordinate corresponding to the depicted reference object in the at least one captured digital photo depicting the reference object.

Method, software product, device and system for determining a direction at a position

A method for calculating a Time To Go value between a vehicle and an intruding object. First and second images of the object are retrieved at first and second points of time. A scaling factor is selected and the second image scaled with the scale factor. The scaled image is resampled to a set position. Correlation values are calculated between the first image and the resampled scaled image for different horizontal displacements and/or different vertical displacements for the resampled scaled image. A maximum correlation value is found based on the correlation values. Selecting the scaling factor, resampling, calculating the correlation values, and finding the maximum correlation values are repeated a second 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 associated scale factor.

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

A collision avoidance system for deciding whether an autonomous avoidance maneuver should be performed in order to avoid a mid-air collision between a host aerial vehicle equipped with the system and an intruding aerial vehicle. At least one electro-optical sensor captures consecutive images of an intruding vehicle such that the vehicle manifests itself as a target point in the images. An image processor estimates the azimuth angle, elevation angle and a first time-to-collision estimate of the time to collision between the host vehicle and the intruding vehicle. The first time-to-collision estimate is estimated based on scale change in the target point between at least two of said consecutive images. A tracking filter is arranged to estimate a second time-to-collision estimate using the azimuth angle, the elevation angle and the first time-to-collision estimate estimated by the image processor as input parameters. A collision avoidance module is arranged to decide whether or not an avoidance maneuver should be performed based on any of at least one parameter, of which at least one is indicative of said second time-to-collision estimate.

Using image sensor and tracking filter time-to-go to avoid mid-air collisions

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.

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Linköping, Sweden

Jimmy Jonsson