Method and apparatus for determining wheel alignment optical target orientation parameters

In a system utilizing an observable optical target having a mounting shaft configured for insertion within an axial bore for rotation therein and an optical camera configured to observe the orientation of a face of said optical target, a method for computing alignment of said optical target face relative to said mounting shaft, comprising the steps of:

• observing said face of said optical target in at least two rotational positions with said optical camera, said optical target releasably secured against rotation at each of said rotational positions;
• calculating, for each of said rotational positions, a set of parameters describing the orientation of said target face;
• and
• computing a compensation vector describing the alignment of said target face relative to said mounting shaft utilizing said sets of calculated parameters.

In an automotive wheel alignment system having a wheel clamp adapted for attachment to a vehicle wheel, an optical target rotatably secured to said wheel clamp by means of a stub shaft inserted within an axial bore of said wheel clamp, and an optical camera configured to observe said optical target, a method for determining alignment of said optical target relative to said stub shaft, comprising the steps of:

• attaching said wheel clamp to said vehicle wheel;
• mounting said optical target on said wheel clamp such that said stub shaft seats within said axial bore;
• observing said optical target in at least two rotational orientations about said stub shaft with said optical camera;
• computing for each rotational orientation a set of parameters describing the orientation of said optical target at said rotational orientation;
• and
• determining an alignment of said optical target relative to said stub shaft utilizing said computed sets of parameters.

A method for manufacturing at least one optical target for use in a vehicle wheel alignment system comprising:

• forming a housing with a plurality of surfaces;
• securing a planar optical target face to one of said surfaces;
• securing a mounting shaft to a second of said surfaces, said mounting shaft having a longitudinal axis oriented with a fixed relationship to said planar optical target face;
• and
• storing, in association with each manufactured optical target, said fixed relationship between said mounting shaft longitudinal axis and said optical target face.

A method for use with a vehicle wheel alignment system comprising a wheel clamp adapter configured for attachment to a vehicle wheel, an optical target having an optical target face and a mounting means arrayed at a known angular relationship to said optical target face and configured for attachment to said wheel clamp adapter, and an optical camera configured to observe said optical target, comprising:

• attaching said wheel clamp adapter to said vehicle wheel in a known relationship to an axis of rotation of said vehicle wheel;
• mounting said optical target to said wheel clamp adapter by said mounting means;
• observing said optical target face with said optical camera to generate at least one image of said optical target face;
• and
• utilizing said known angular relationship between said mounting means and said optical target face, said known relationship of said wheel clamp adapter to said axis of rotation of said vehicle wheel, and said image of said optical target face observed by said optical camera to determine the orientation of said axis of rotation of said vehicle wheel.

A method for use with a vehicle wheel alignment system comprising a wheel clamp adapter configured for attachment to a vehicle wheel an optical target having an optical target face and a mounting means arrayed at a known angular relationship to said optical target face and configured for attachment to said wheel clamp adapter, and an optical camera configured to observe said optical target, comprising:

• attaching said wheel clamp adapter to said vehicle wheel in a known relationship to an axis of rotation of said vehicle wheel;
• mounting said optical target to said wheel clamp adapter by said mounting means;
• observing said optical target face with said optical camera to generate at least one image of said optical target face:
• utilizing said known angular relationship between said mounting means and said optical target face, and said image of said optical target face observed by said optical camera to determine the orientation of said axis of rotation of said vehicle wheel;
• and
• wherein said known angular relationship between said mounting means and said optical target face is calculated from a plurality of observations of said optical target face in a plurality of rotational positions about a longitudinal axis of said mounting means.

In a vehicle wheel alignment system utilizing at least one observable optical target having a mounting means with a rotational axis, a wheel clamp configured for attachment to a vehicle wheel, and an optical camera configured to observe said optical target for determining the orientation thereof, a method for using said optical target comprising the steps of:

• observing said optical target in at least two rotational positions about said mounting means rotational axis with said optical camera;
• determining an orientation of said optical target at each of said rotational positions;
• computing the alignment of said optical target relative to said rotational axis utilizing said determined orientations;
• and
• utilizing said computed alignment to determine an alignment of said rotational axis of said vehicle wheel when said optical target is mounted on said wheel clamp attached to said vehicle wheel.