Fuji Electric Co., Ltd.

Takehide Hirabayashi

Hideo Shimizu

Akio Izumi

Taichi Tanigawa

Takayuki Usuda

Akihiko Okabe

A distance-measuring apparatus is formed of a photographic device formed of a pair of image-forming lenses and photosensor arrays for taking images of an object through the image-forming lenses, and a calculating device electrically connected to the photosensor arrays for calculating a distance to an object to be measured by two images of the object taken by the photographic device based on a triangulation principle. The calculating device calculates the distance to the object by an amount of shift determined based on an inter-optical-axis distance of the pair of image-forming lenses and photographed images of a reference object having a pattern of a periodic structure repeated at an interval same as the inter-optical-axis distance; a difference in offsets of image-forming positions on the photosensor arrays caused by a medium located between the apparatus and the measured object, with the difference being detected based on the amount of the shift; and an amount of shift detected when the distance to the measured object is measured.

Distance-measuring apparatus

In a distance detection method, a pair of image data representing a pattern of images is obtained by using a pair of image sensors for receiving optical images. Then, a detection target extracted from each of the image data is captured while sequentially shifting positions of divisions in respective groups of divisions from window part data corresponding to a visual field to provide combinations, each having a pair of divisions, and a correlation value is calculated between each pair of the divisions. Also, a precision at a best correlation point as an indicator of reliability of the best correlation is obtained based on a changing condition of the correlation value near a shift value where the best correlation value has been calculated. Finally, a distance to the detection target is obtained by determining that the detection target is present in the visual field seen through the window corresponding to the window part data only when the precision exceeds a predetermined level.

Distance detection method using images

A distance-measuring apparatus includes light-sensitive devices formed of optical sensor arrays disposed on image-forming surfaces of right and left image-forming lenses, respectively. The apparatus uses image data from the optical sensor arrays of the light-sensitive devices to determine the distance from an object such as a vehicle in front of the apparatus via a distance detection circuit and capable of detecting condensation or a foreign particle obscuring a cover glass or defective pixels in the optical sensor arrays. In a defective condition, a defective visibility sensor emits an alarm signal to alert the operator.

A method of the invention corrects a detection error, caused by an assembly error, in a distance or a distance-related index detected from an image captured in the visual field of an image detection module including an optical device and a pair of image sensing devices, each including a plurality of image sensors. In the method, the visual field is divided into windows disposed in a two-dimensional matrix format in order to detect the distance or a parallax for a pair of images in each window; the characteristics of an error is expressed in a detected value caused by an angle error in the assembly of the image detection module, as a quadratic polynomial for two angle variables indicating the position of the window within the visual field; parallax for a plurality of windows is detected after a test sample image has been provided to the module; the coefficient value for each term in the polynomial is determined based on the results of the detection, and these values are stored in a storage device; and, when using the image detection module to detect actual distances, the detected value for each window is corrected by adding to it the value of the polynomial to which the stored values of the coefficients and the values of the variables indicating the position of the window are applied.

Method for correcting detected distance values

An inter-vehicle distance to a preceding or following vehicle is reliably determined by using a simple processing, to alert the following vehicle to approach a dangerous range. The distance measurement apparatus includes a pair of light-receiving devices disposed on image-forming surfaces of lenses and having sensor lines and measurement windows on each sensor line at a certain interval, a distance detection device, a white line detection device and a vehicle detection device. The distance detection device detects distances at points, the coordinates of which are specified by the sensor line numbers and measurement window addresses. By using the detection results, the white line detection device detects a sensor line in which a white line on a road surface is present. By using the detection results obtained from the distance detection device relating to the sensor lines in which the white line is not present, the vehicle detection device checks a presence of a vehicle and outputs information on the inter-vehicle distance and the direction of the vehicle. The following vehicle may be alerted by flashing the brake lights.

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Tokyo, Japan

Takehide Hirabayashi