Hand-held tyre scanner

1. A hand-held device for obtaining a three-dimensional topological surface profile of a tyre, the device comprising:

a base comprising an aperture;

a light source arranged in use to generate an elongate pattern of light, and to project said pattern of light through the aperture onto a rolling surface of the tyre;

a detector arranged to image a region of the rolling surface of the tyre;

a plurality of pairs of guide wheels mounted on respective axles mounted on the base, wherein the guide wheels on adjacent axles are linked by gears; and

a rotary encoder arranged to generate a signal corresponding to rotation of an axle.

2. The hand-held device as claimed in claim 1 , wherein the pairs of guide wheels are arranged in a concave arc extending in a direction perpendicular to the axles.

3. The hand-held device as claimed in claim 1 , further comprising at least one processor configured to generate a three-dimensional topological surface profile of the tyre using data obtained from an image of the rolling surface of the tyre and the signal generated by the rotary encoder.

4. The hand-held device as claimed in claim 3 , wherein the at least one processor is further configured to identify tyre side walls by analysing a directionality of the signal generated by the rotary encoder to determine a position of an outer edge and an inner edge of the tyre.

5. The hand-held device as claimed in claim 1 , wherein the rotary encoder is disposed in a sealed housing in the device.

6. The hand-held device as claimed in claim 1 , wherein the projected pattern of light is oriented in a direction transverse to a direction of travel of the device when the device is rolled on the guide wheels.

7. The hand-held device as claimed in claim 1 , further comprising a visual, audible and/or haptic indicator configured to provide visual, audible and/or haptic feedback to indicate that a scan is complete, a scan is incomplete, or that insufficient or poor data has been obtained from a scanned area.

8. The hand-held device as claimed in claim 1 , wherein the base is connected to a housing of the device via a hinge such that the base can be rotated away from the housing to expose the aperture.

9. The hand-held device as claimed in claim 1 , wherein: the gears comprise first gears and second gears, the first gears link axles adjacent to the aperture and the first gears are displaced relative to the second gears to accommodate the aperture.

10. The hand-held device as claimed in claim 1 , further comprising a wireless transceiver for connecting to an external device, wherein the wireless transceiver is configured to communicate to the external device to provide measurement data to the external device.

11. The hand-held device according to claim 1 wherein the hand-held device is configured to slide along a guide rail.

12. A method of obtaining data for generating a three-dimensional topological surface profile of a tyre, using a hand-held device, the method comprising:

generating an elongate pattern of light;

projecting said pattern of light through an aperture in a base of the hand-held device onto a rolling surface of the tyre;

imaging a region of the rolling surface of the tyre;

moving the device over the rolling surface of the tyre on a plurality of pairs of guide wheels mounted on respective axles mounted on the base, wherein the guide wheels on adjacent axles are linked by gears; and

using a rotary encoder to generate a signal corresponding to rotation of an axle.

13. The method as claimed in claim 12 , further comprising generating a three-dimensional topological surface profile of the tyre using data obtained from an image of the rolling surface of the tyre and the signal generated by the rotary encoder.

14. The method as claimed in claim 13 , further comprising identifying tyre side walls by analysing a directionality of the signal generated by the rotary encoder to determine a position of an outer edge and an inner edge of the tyre.

15. The method as claimed in claim 12 , comprising projecting the pattern of light so that the pattern of light is oriented in a direction transverse to a direction of travel of the device when the device is rolled on the guide wheels.

16. The method as claimed in claim 12 , wherein the device comprises a battery, the method further comprising the device entering a low power or sleep mode when no signal is received from the rotary encoder.

17. The method as claimed in claim 12 , further comprising communicating with an external device to provide measurement data to the external device;

communicating data obtained from an image of the rolling surface of the tyre and the signal generated by the rotary encoder to the external device; and

using the external device to determine one or more of: a three-dimensional topological surface profile of the tyre; wheel alignment information; tyre inflation information; and stopping distance information.

18. The method as claimed in claim 12 , comprising using the hand-held device to determine one or more of: a three-dimensional topological surface profile of the tyre; wheel alignment information; tyre inflation information; and stopping distance information.

19. The method as claimed in claim 12 , further comprising:

imaging a vehicle registration plate to generate an image;

identifying the vehicle registration plate based on the image;

retrieving vehicle information and/or tyre information based on the identified vehicle registration plate; and

using said retrieved information to determine one or more of: a three-dimensional topological surface profile of the tyre; wheel alignment information; tyre inflation information; and stopping distance information.

20. The method as claimed in claim 12 , further comprising:

placing a guide rail in a fixed relationship relative to the rolling surface of the tyre; and

moving the hand-held device along the guide rail as the device moves over the surface of the tyre.