Method For Evaluating Component Calibration In Machine Vision Vehicle Wheel Alignment System

A method for evaluating a machine vision vehicle wheel alignment system having at least four cameras including, for the left and right sides of a vehicle positioned on a vehicle support surface, a front camera with an associated field of view disposed to view a front wheel of the vehicle, and a rear camera with an associated field of view disposed to view a rear wheel of the vehicle, said rear camera associated field of view and said front camera associated field of view intersecting to define an overlapping region, comprising:

• providing a fixture having identifiable features;
• acquiring from said four cameras, a set of images of said identifiable features of said fixture disposed on said vehicle support surface at a plurality of positions, at least one of said plurality of positions disposed within said overlapping regions for said front and rear cameras on each side of the vehicle;
• processing said set of acquired images to calibrate said plurality of cameras and said vehicle support surface associated with said machine vision wheel alignment system;
• repeating said step of acquiring to acquire a second set of images while said fixture is disposed on said vehicle support surface at a position which is within the overlapping region of the fields of view associated with said front and rear cameras on each side of the vehicle support surface;
• and
• processing said second set of acquired images to establish a performance metric for said calibrated machine vision wheel alignment system.

A method for calibrating a machine vision vehicle wheel alignment system having at least four cameras including, for the left and right sides of a vehicle positioned on a vehicle support surface, a front camera with an associated field of view disposed to view a front wheel of the vehicle, and a rear camera with an associated field of view disposed to view a rear wheel of the vehicle which partially overlaps said front camera associated field of view, comprising:

• providing a fixture having identifiable features;
• acquiring from said four cameras, a set of images of said identifiable features of said fixture disposed on said vehicle support surface at a plurality of positions, at least one of said plurality of positions disposed within a region of said overlapping fields of view for said front and rear cameras on each side of the vehicle;
• and
• processing said set of acquired images to generate calibration data associated with said machine vision wheel alignment system.

A method for establishing coordinate transforms between cameras in a machine vision vehicle service system, comprising

• acquiring, from a first camera, at least two images of a portion of a fixture positioned within the field of view of the first camera, at least one of said images acquired with said fixture positioned within a region of overlapping fields of view of said first camera and a second camera;
• acquiring, from said second camera, at least two images of said portion of said fixture positioned within the field of view of the second camera, at least one of said images acquired with said portion of said fixture positioned within said region of overlapping fields of view of said first camera and said second camera;
• and
• processing said set of acquired images from each of said cameras to establish a coordinate transform between reference frames of the first and second cameras.

A method for establishing coordinate transforms between multiple cameras in a machine vision vehicle service system viewing portions of a vehicle support surface, comprising:

• providing a fixture adapted to receive a machine vision optical target at each opposing end;
• disposing said fixture transversely across said vehicle support surface, such that a first optical target disposed at a first opposing end is within the field of view of at least a first camera of the machine vision vehicle service system, and a second optical target disposed at a second opposing end is within the field of view of at least a second camera of the machine vision vehicle service system, said first and second cameras disposed on opposite sides of a longitudinal centerline of the vehicle support surface;
• acquiring, from each camera, at least one image of the optical targets within the respective fields of view;
• displacing the first opposing end of the fixture along the vehicle support surface to a next position which is longitudinally offset from said second end, and acquiring from each camera, at least a second image of the optical targets within the respective fields of view;
• displacing the second opposing end of the fixture along the vehicle support surface to a subsequent position in the same direction as said displacement of said first end to a next position which is longitudinally offset from said first end, and acquiring from each camera, a at least a third image of the optical targets within the respective fields of view;
• and
• processing said acquired images to establish at least a coordinate transform between the first and second cameras.

A method for using a machine vision vehicle wheel alignment system having cameras for observing the left and right sides of a vehicle positioned on a vehicle support surface, comprising:

• providing a fixture having identifiable features;
• acquiring from said cameras, a set of images of said identifiable features of said fixture disposed on said vehicle support surface at a plurality of positions;
• and
• processing said set of acquired images to generate characterization data for a portion of said vehicle support surface associated with said machine vision wheel alignment system.