Method and device for determining distances on a vehicle
A method for determining distances for chassis measurement of a vehicle having a body and at least one wheel includes determining a center of rotation of a wheel of the vehicle by projecting a structured light pattern at least onto the wheel, recording a light pattern reflected by the wheel using a calibrated imaging sensor system, determining a 3D point cloud from the reflected light pattern, and determining the center of rotation of the wheel from the 3D point cloud. The method also includes determining a point on the body by evaluating the previously determined 3D point cloud or by evaluating a plurality of grey-scale images recorded under unstructured illumination. A height level is determined as a vertical distance between the center of rotation of the wheel and the point on the body.
1. A method for determining distances for measuring a chassis of a vehicle having a body and at least one wheel comprising:
projecting a structured light pattern at least onto the wheel;
recording a light pattern reflected by the wheel with an imaging sensor system;
determining a 3-D cloud diagram from the reflected light pattern;
determining a center of rotation of the wheel by:
adapting a parametric surface model of the wheel to the 3-D cloud diagram for various rotational positions of the wheel;
calculating the wheel normal vector for the respective rotational position of the wheel; and
calculating the rotational axis and therefore the center of rotation of the wheel from the spatial movement of the wheel normal vector;
determining a point on the body by:
illuminating the vehicle with unstructured illumination;
driving the illuminated vehicle past an arrangement with at least two imaging sensors;
recording a number of grayscale images while the vehicle is driving past the imaging sensors;
determining the point on a lower edge of a wheelhouse in the body by evaluating the grayscale images, the evaluation of the grayscale images further comprising:
performing edge detection to identify a plurality of edges in the 3-D contours;
performing stereo correspondence assignment of the plurality of edges; and
performing 3-D triangulation and classification of the lower edge of the wheelhouse with reference to the stereo correspondence assignment of the plurality of edges; and
determining a ride height as a vertical distance between the center of rotation of the wheel and the point on the lower edge of the wheelhouse in the body.
2. The method of claim 1 , wherein the determination of the ride height includes averaging a number of ride heights which have been determined from a plurality of grayscale images.
3. The method of claim 1 , wherein the evaluation of the grayscale images includes disparity measurement by use of stereo methods, the generation of a 3-D cloud diagram from the disparity measurement and classification of the wheelhouse lower edge.
4. The method of claim 1 , wherein the edge detection is performed with a Canny Edge filter.
5. A device for determining distances for measuring a chassis of a vehicle having a body and at least one wheel, comprising:
at least one projector configured to project a structured light pattern onto at least one wheel of the vehicle and an area of the body surrounding the wheel;
at least one imaging sensor system configured to record a light pattern reflected by the wheel and the area of the body surrounding the wheel;
at least one image recording device configured to record a number of grayscale images while the vehicle is driving past the image recording device; and
at least one evaluation unit configured to:
determine a 3-D cloud diagram from the reflected light pattern;
adapt a parametric surface model of the wheel to the 3-D cloud diagram;
determine the respective wheel normal vector for various rotational positions of the wheel;
calculate the rotational axis and therefore the center of rotation of the wheel from the spatial movement of the wheel normal vector;
determine a point on a wheelhouse in the body by evaluating the gray scale images, the evaluation unit being further configured to:
perform edge detection to identify a plurality of edges in the 3-D contours;
perform stereo correspondence assignment of the plurality of edges; and
perform 3-D triangulation and classification of the lower edge of the wheelhouse with reference to the stereo correspondence assignment of the plurality of edges; and
determine the ride height as a vertical distance between the center of rotation of the wheel and the point on the wheelhouse in the body.
6. The system of claim 5 , wherein the evaluation of the grayscale images includes disparity measurement by use of stereo methods, the generation of a 3-D cloud diagram from the disparity measurement and classification of the wheelhouse lower edge.
7. The system of claim 5 , wherein the edge detection is performed with a Canny Edge filter.