초록 ▼

An apparatus and method for calibrating machine vision measuring systems that have more than one camera are disclosed. A first calibration target is mounted in a fixed relationship to a first camera of the machine vision measuring system. A third camera mounted in a fixed relationship to a second ca

An apparatus and method for calibrating machine vision measuring systems that have more than one camera are disclosed. A first calibration target is mounted in a fixed relationship to a first camera of the machine vision measuring system. A third camera mounted in a fixed relationship to a second camera of the machine vision measuring system. Second and third calibration targets are mounted in a fixed relationship to one another and viewable by the first camera and by the third camera. A data processor is programmed to compute calibration of the first camera and the second camera, based on a position of the second calibration target relative to the third calibration target and a position of the first camera with respect to the third camera. The apparatus and method provide a way to continuously measure the positions of the cameras used in the measuring system to calibrate the system.

대표청구항 ▼

1. A wheel alignment method using a machine measuring system that has a first measuring device and a second measuring device, wherein the first measuring device and the second measuring device are image-capturing devices, the method comprising the steps of:mounting a first calibration target in a fi

1. A wheel alignment method using a machine measuring system that has a first measuring device and a second measuring device, wherein the first measuring device and the second measuring device are image-capturing devices, the method comprising the steps of:mounting a first calibration target in a first fixed predetermined relationship to the first measuring device of the machine measuring system, wherein the first measuring device is configured to generate a positional parameter of a first wheel of a vehicle;mounting a third measuring device in a second fixed predetermined relationship to the second measuring device of the machine measuring system, wherein the second measuring device is configured to generate a positional parameter of a second wheel of the vehicle, and the third measuring device is an image-capturing device configured to repeatedly measure a relative position between the third measuring device and the calibration target;storing a reference value that represents a reference position of the first calibration target relative to the third measuring device;repeatedly determining a relative measuring-device position value representing the position of the first measuring device relative to the second measuring device based on a position of the first calibration target relative to the third measuring device;calculating alignment parameters of the vehicle based on the relative measuring-device position value, the first fixed predetermined relationship, the second fixed predetermined relationship, the positional parameter of the first wheel, and the positional parameter of the second wheel; andperiodically comparing the reference value with a new measurement of the relative position between the third measuring device and the calibration target.2. A method as recited in claim 1,further including the step of raising an alert alarm if the reference value differs from the new value beyond an acceptable amount.3. A method as recited in claim 2, including applying the difference in the calibration value and the new value to update the relative measuring-device position value.4. A method as recited in claim 2 including, upon recognizing that the calibration value differs from the new value beyond an acceptable amount, recalculating the relative measuring-device position value.5. A method as recited in claim 1, wherein the relative position between the first measuring device and the second measuring device is computed based on a position of the first calibration target relative to a second calibration target.6. A method as recited in claim 5, wherein the position of the first calibration target relative to the second calibration target is obtained by using a fourth measuring device which provides information to calculate the position of the first calibration target relative to the second calibration target.7. A method as recited in claim 5 wherein:the position of the first calibration target relative to the second calibration target is obtained by using an image-capturing device;images of the first calibration target and the second calibration target are provided by placing the first calibration target and the second calibration target in the view of the image-capturing device; andthe images of the first calibration target and the second calibration target are applied to calculate the position of the first calibration target relative to the second calibration target.8. A method as recited in claim 1, further comprising the step of computing the relative measuring-device position value of the machine measuring system while the first measuring device and the second measuring device of the machine measuring system are measuring targets of objects under measurement.9. A method as recited in claim 1, further comprising the steps of:computing a modified relative measuring-device position value of the machine measuring system while the first measuring device and the second measuring device of the machine measuring system are measuring targets of objects under measurement, andmodifying measurements produced by measuring the targets of objects under measurement based on the modified relative measuring-device position value of the machine measuring system.10. A method as recited in claim 9, wherein the step of modifying measurements produced by measuring the targets of objects under measurement based on the modified relative measuring-device position value of the machine measuring system is performed only when the modified relative measuring-device position value differs from the relative measuring-device position value by more than a predetermined value.11. The method of claim 1, wherein each of the first measuring device, the second measuring device, and the third measuring device is an image-capturing device that performs measurements of objects by capturing images.12. A method as recited in claim 1, wherein any of the first measuring device, the second measuring device, and the third measuring device is an image-capturing device that performs measurements of objects by capturing images.13. The method of claim 1, wherein the computer periodically determines the relative position between the first measuring device and the second measuring device.14. A wheel alignment method using a machine measuring system that has a first measuring device and a second measuring device the method comprising the steps of:mounting a first calibration target in a first fixed predetermined relationship to the first measuring device of the machine measuring system, wherein the first measuring device is configured to generate a positional parameter of a first wheel of a vehicle;mounting a third measuring device in a second fixed predetermined relationship to the second measuring device of the machine measuring system, wherein the second measuring device is configured to generate a positional parameter of a second wheel of the vehicle, and the third measuring device is an image-capturing device configured to measure a relative position between the third measuring device and the calibration target;repeatedly determining a relative measuring-device position value representing the position of the first measuring device relative to the second measuring device based on a position of the first calibration target relative to the third measuring device;calculating alignment parameters of the vehicle based on the relative measuring-device position value, the first fixed predetermined relationship, the second fixed predetermined relationship, the positional parameter of the first wheel, and the positional parameter of the second wheel;storing a value that represents the position of the first calibration target relative to the third measuring device as a calibration value;periodically measuring a new value that represents the position of the first calibration target relative to the third measuring device;periodically comparing the new value with the calibration value; andif the calibration value differs from the new value beyond an acceptable amount, then raising an alert alarm.15. A wheel alignment method of using a first measuring device and a second measuring device, wherein the first measuring device and the second measuring device are image-capturing devices, the method comprising the steps of:mounting near the first measuring device a calibration device in which the position of the calibration device relative to the first device is predetermined; wherein the first measuring device is configured to measure a positional parameter of a first wheel of a vehicle and the calibration device is an image-capturing device;mounting near the second measuring device a calibration target in which the position of the calibration target relative to the second device is predetermined; wherein the second measuring device is configured to measure a positional parameter of a second wheel of the vehicle;storing a reference value that represents a reference position of the first calibration target relative to the third measuring-device;repeatedly measuring the position of the calibration device relative to the calibration target;accessing computer-stored data related to the position of the calibration device relative to the first measuring device and the position of the calibration target relative to the second measuring device;using a computer, repeatedly determining the position of the first measuring device relative to the second measuring device based on:the position of the calibration device relative to the first measuring device;the position of the calibration target relative to the second measuring device; andthe position of the calibration device relative to the calibration target; andcalculating an alignment status of the vehicle based on the position of the first measuring device relative to the second measuring device, the positional parameter of the first vehicle wheel, and the positional parameter of the vehicle second wheel; andperiodically comparing the reference value with a new measurement of the relative position between the third measuring device and the calibration target.16. The method of claim 15, wherein a computer is used to determine the position of the first measuring device relative to the second measuring device periodically.17. A wheel alignment method using a machine measuring system that has a first measuring device and a second measuring device for measuring positional parameters, wherein a first calibration device is in a first known positional relationship relative to the first measuring device, and a second calibration device is in a second known positional relationship relative to the second measuring device, the first calibration device and the second calibration device are used to measure a relative position of the first calibration device relative to the second calibration device, the first measuring device, the second measuring device and at least one of the first and second calibration devices are image-capturing devices, the method comprising the machine-implemented steps of:receiving a signal generated by the first measuring device representing positional parameters of a first wheel of a vehicle;receiving a signal generated by the second measuring device representing positional parameters of a second wheel of the vehicle;storing a reference value that represents a reference position of the first calibration target relative to the third measuring device;repeatedly receiving a signal representing a relative position between the first calibration device and the second calibration device, wherein the relative position between the first calibration device and the second calibration device is measured by the first calibration device and the second calibration device;accessing data representing the first known positional relationship and the second known positional relationship;repeatedly calculating a relative position between the first measuring device and the second measuring device based on the signal representing the relative position between the first calibration device and the second calibration device, the first known positional relationship and the second known positional relationship;determining alignment parameters of the vehicle based on the relative position between the first measuring device and the second measuring device, the positional parameter of the first wheel, and the positional parameter of the second measuring device; andperiodically comparing the reference value with a new measurement of the relative position between the third measuring device and the calibration target.18. A wheel alignment method as recited in claim 17, wherein the first measuring device, the second measuring device, the first calibration device or the second calibration device are selected from a group consisting of: an image-capturing device, a gravity gauge configured to detect movement of an object, a string gauge configured to detect movement of an object, and a light source configured to direct a light beam at a detector.19. A wheel alignment method as recited in claim 17, further including the step of:raising an alert alarm in response to the reference value differing from the new value beyond an acceptable amount.20. A wheel alignment method as recited in claim 17, wherein each of the first measuring device, the second measuring device, and the first calibration device is an image-capturing device that performs measurements of objects by capturing images.21. A wheel alignment method using a machine measuring system that has a first measuring device and a second measuring device for measuring positional parameters, wherein a first calibration device is in a first known positional relationship relative to the first measuring device, and a second calibration device is in a second known positional relationship relative to the second measuring device, the first calibration device and the second calibration device are used to measure a relative position of the first calibration device relative to the second calibration device, and at least one of the first and second calibration devices is an image-capturing device, the method comprising the machine-implemented steps of:receiving a signal generated by the first measuring device representing a positional parameter of a first wheel of a vehicle;receiving a signal generated by the second measuring device representing a positional parameter of a second wheel of the vehicle;storing a reference value that represents a reference position of the first calibration target relative to the third measuring device;periodically receiving a signal representing a relative position between the first calibration device and the second calibration device, wherein the relative position between the first calibration device and the second calibration device is measured by the first calibration device and the second calibration device;accessing data representing the first known positional relationship and the second known positional relationship;repeatedly calculating a relative position between the first measuring device and the second measuring device based on the signal representing the relative position between the first calibration device and the second calibration device, the first known positional relationship and the second known positional relationship;determining an alignment status of the vehicle based on the signal representing a relative position between the first measuring device and the first wheel, and the positional parameter of the first wheel, and the positional parameter of the second wheel; andperiodically comparing the reference value with a new measurement of the relative position between the third measuring device and the calibration target.