초록 ▼

A method is provided for calibrating a sensor pod of a wheel alignment system, the sensor pod including a housing rotatably mounted on a spindle, and an image sensor in the housing having a viewing axis oriented in a direction substantially normal to an axis of rotation of the spindle for imaging a

A method is provided for calibrating a sensor pod of a wheel alignment system, the sensor pod including a housing rotatably mounted on a spindle, and an image sensor in the housing having a viewing axis oriented in a direction substantially normal to an axis of rotation of the spindle for imaging a target affixed to an object such as a vehicle wheel. An example of the method includes mounting the pod on a fixture via the pod spindle such that the pod spindle is stationary, and positioning a target to allow imaging of the target with the pod image sensor. The pod is rotated such that its image sensor obtains images of the target in at least two rotational positions, and the images of the target at the at least two rotational positions are processed to determine the location of the axis of rotation of the spindle relative to the image sensor.

대표청구항 ▼

What is claimed is: 1. A method for calibrating a sensor pod of a wheel alignment system, the sensor pod comprising a housing rotatably mounted on a spindle, and an image sensor in the housing having a viewing axis oriented in a direction substantially normal to an axis of rotation of the spindle f

What is claimed is: 1. A method for calibrating a sensor pod of a wheel alignment system, the sensor pod comprising a housing rotatably mounted on a spindle, and an image sensor in the housing having a viewing axis oriented in a direction substantially normal to an axis of rotation of the spindle for imaging a target affixed to an object such as a vehicle wheel, the method comprising: mounting the pod on a fixture via the pod spindle such that the pod spindle is stationary; positioning a target to allow imaging of the target with the pod image sensor; rotating the pod such that its image sensor obtains images of the target in at least two rotational positions; and processing the images of the target at the at least two rotational positions to determine the location of the axis of rotation of the spindle relative to the image sensor. 2. The method of claim 1, comprising providing the target having a bar with an optical element at each of two distal ends; wherein determining the location of the spindle axis of rotation of the pod relative to the image sensor comprises rotating the pod such that the image sensor obtains at least one image of each of the optical elements. 3. The method of claim 1, wherein the pod further comprises a gravity-type camber gauge, and the fixture comprises a rotatable bar, the method comprising: mounting the pod on the rotatable bar of the fixture via the pod spindle; placing the fixture such that the fixture is substantially parallel to a surface of a reference plane; rotating the bar to a plurality of rotational positions; obtaining a measurement of the camber gauge at each of the plurality of rotational positions of the bar; and processing the camber gauge measurements to obtain a zero camber reference value for the pod. 4. The method of claim 1, comprising: providing a pair of the sensor pods, each of the sensor pods comprising a cross-toe sensor and a cross-toe target in the housing, the cross-toe sensor oriented in a direction along the spindle axis of rotation for sensing the cross-toe target of the other sensor pod; mounting the pods on a rotatable bar of the fixture via the pod spindles such that the pod spindles are substantially concentric to each other; rotating the bar of the fixture to obtain data relating to the cross-toe targets in a plurality of rotational positions; and processing the data relating to the cross-toe targets to determine a zero toe reference value for each of the cross-toe sensors. 5. The method of claim 1, wherein the pod further comprises a gravity-type pitch gauge, the method comprising: positioning the fixture on a substantially level surface; positioning the target such that it is rotatable about a substantially vertical axis; rotating the target such that the pod image sensor obtains images of the target in at least two rotational positions; processing the images of the target at the at least two rotational positions to determine the location of the axis of rotation of the target; and processing the location of the axis of rotation of the target to obtain a zero caster reference value for the pod. 6. The method of claim 5, wherein the pod further comprises a gravity-type camber gauge, the method comprising processing the location of the axis of rotation of the target to obtain a zero camber reference value for the pod. 7. The method of claim 1, wherein the pod comprises a rotational sensor on its spindle for measuring an angular amount of spindle rotation, the method comprising: obtaining a rotational sensor measurement at each of the at least two rotational positions of the pod; determining a measured angular spindle rotation based on the obtained rotational sensor measurements; processing the images of the target at the at least two rotational positions to determine a calculated angular spindle rotation; and comparing the measured angular spindle rotation and the calculated angular spindle rotation to calibrate the rotational sensor. 8. A method of aligning the wheels of a motor vehicle, the method comprising: attaching a target to each wheel of a first axle of the vehicle; attaching a sensor pod to each wheel of a second axle of the vehicle, each sensor pod having an image sensor mounted thereon for imaging a corresponding one of the targets; rotating each wheel of the first axle while the wheels of the second axle remain stationary such that the image sensors obtain images of their corresponding targets in at least two rotational positions; and processing the images of each target at the at least two rotational positions to determine the orientation of an axis of rotation of each wheel of the first axle. 9. The method of claim 8, wherein each sensor pod has a housing rotatably mounted on a spindle, and a cross-toe sensor in the housing oriented in a direction along the spindle axis of rotation for sensing a cross-toe target of the other sensor pod, wherein the image sensor has a viewing axis oriented in a direction substantially normal to the spindle axis of rotation for imaging its corresponding target, the method further comprising: imaging each of the targets with their corresponding image sensors in a single position; calculating a vector between each of the image sensors and a corresponding point in space relative to their corresponding target; obtaining data related to the cross-toe targets using the cross-toe sensors; calculating a total toe of the wheels of the second axle based on the data related to the cross-toe targets; and calculating an individual toe measurement for each wheel on the second axle based on the vector and the cross-toe data. 10. The method of claim 8, comprising calculating at least one of the toe and the camber of each wheel of the first axle based on the location of the axis of rotation of each wheel of the first axle. 11. The method of claim 8, wherein the wheels of the first axle are steerable, the method comprising: steering the wheels of the first axle while the wheels of the first axle are prevented from turning about the axle, and the wheels of the second axle remain stationary, such that the image sensors obtain images of their corresponding targets in at least two steered positions; and processing the images of each target at the at least two steered positions to determine at least one of a caster and steering axis inclination of each wheel of the first axle. 12. A method of aligning a pair of opposing wheels of one axle of a motor vehicle, the method comprising: providing a pair of sensor pods, each sensor pod having an image sensor for imaging a target affixed to an object such as a vehicle wheel, and a cross-toe sensor for sensing a cross-toe target of the other sensor pod; attaching a target to each of the pair of wheels to be aligned; positioning the sensor pods to allow imaging of one of the targets with each pod image sensor, and to allow sensing of the cross-toe target of each pod by the cross-toe sensor of the other pod; rotating each wheel to be aligned such that the image sensors obtain images of their corresponding targets in at least two rotational positions; obtaining data related to the cross-toe targets using the cross-toe sensors; processing the images of each target at the at least two rotational positions to determine an image-derived toe of each wheel to be aligned; processing the data related to the cross-toe targets to determine the cross-toe of the pods; and calculating the toe of the wheels to be aligned based on the image-derived toe of each wheel and the cross-toe of the pods. 13. The method of claim 12, wherein each of the sensor pods comprises a gravity camber gauge, the method comprising: processing the images of each target at the at least two rotational positions to determine an image-derived camber of each wheel to be aligned relative to their corresponding image sensor; obtaining a measurement of each camber gauge; and calculating the camber of each of the wheels to be aligned based on the image-derived camber of each wheel and the corresponding pod's camber gauge measurement. 14. The method of claim 12, wherein the wheels to be aligned are steerable, the method comprising: steering the wheels to be aligned while they are prevented from turning, such that the image sensors obtain images of their corresponding targets in at least two steered positions; and processing the images of each target at the at least two steered positions to determine at least one of a caster, caster trail, scrub radius and steering axis inclination of each wheel to be aligned.