# US 10,121,255 B2 · Optical sensor for odometry tracking to determine trajectory of a wheel > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,121,255 B2 - Document ID: US10121255B2 - Status: Granted - Kind: B2 - Application number: 14/930,668 - Filed: 2015-11-03 - Published: 2017-05-04 - Granted: 2018-11-06 - Earliest claimed: 2015-11-03 - Assignees: Pixart Imaging Inc. - Applicants: PixArt Imaging (Penang) SDN. BHD. - Inventors: Keen-Hun Leong; Boon-How Kok; Dennis Dominic Donald - Web page: https://patentgrep.com/patent/US10121255B2 ## CPC - G06T 7/20: Analysis of motion (motion estimation for coding, decoding, compressing or decompressing digital video signals H04N19/43, H04N19/51) - B60W 30/00: Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of vehicle sub-units - B62D 15/024: {Other means for determination of steering angle without directly measuring it, e.g. deriving from wheel speeds on different sides of the car} - G01C 22/00: Measuring distance traversed on the ground by vehicles, persons, animals or other moving solid bodies, e.g. using odometers, using pedometers - G01C 25/00: Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass (testing, calibrating or compensating compasses G01C17/38) - G06F 3/0362: with detection of one-dimensional [1D] translations or rotations of an operating part of the device, e.g. scroll wheels, sliders, knobs, rollers or belts - H04N 23/90: Arrangement of cameras or camera modules, e.g. multiple cameras in TV studios or sports stadiums - G01C 21/26: specially adapted for navigation in a road network - G06T 2207/30241: Trajectory - G06T 2207/30252: Vehicle exterior; Vicinity of vehicle - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL - B60W: CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT - B62D: MOTOR VEHICLES; TRAILERS (steering, or guiding on a desired track, of agricultural machines or implements A01B69/00; wheels, castors, axles, increasing wheel adhesion B60B; vehicle tyres, tyre inflation or tyre changing B60C; connections between vehicles of a train or the like B60D; vehicles for use on rail and road, amphibious or convertible vehicles B60F; suspension arrangements B60G; heating, cooling, ventilating or other air treating devices B60H; windows, windscreens, non-fixed roofs, doors or similar devices, protective coverings for vehicles not in use B60J; propulsion plant arrangements, auxiliary drives, transmissions, controls, instrumentation or dashboards B60K; electric equipment or propulsion of electrically-propelled vehicles B60L; power supply for electrically-propelled vehicles B60M; passenger accommodation not otherwise provided for B60N; adaptations for load transportation or to carry special loads or objects B60P; arrangement of signalling or lighting devices, the mounting or supporting thereof or circuits therefor, for vehicles in general B60Q; vehicles, vehicle fittings or vehicle parts not otherwise provided for B60R; servicing, cleaning, repairing, supporting, lifting, or manoeuvring, not otherwise provided for, B60S; brake arrangements, brake control systems or parts thereof B60T; air-cushion vehicles B60V; motor-cycles, accessories therefor B62J, B62K; testing of vehicles G01M) - G01C: MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY (measuring liquid level G01F; radio navigation, determining distance or velocity by use of propagation effects, e.g. Doppler effects, propagation time, of radio waves, analogous arrangements using other waves G01S) - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract An optical sensor system for determining trajectory of a wheel includes: a wheel mounted in a wheel arch having an outer surface covered with evenly-spaced wheel treads; a plurality of optical sensors mounted in the wheel arch but not touching the wheel, for performing a plurality of counts corresponding to respectively capturing a plurality of images of the wheel according to the wheel treads; and a plurality of clear casings respectively mounted in the wheel arch between the wheel and the plurality of optical sensors, but not touching the wheel. The captured images are compared with a reference image to determine a 2D displacement and a calculation is further performed to convert the measured 2D displacement of the wheel from its original position into a distance the wheel travels along a path in order to determine the wheel trajectory. ## Claims ### Claim 1 An optical sensor system mounted in a wheel arch in a car for counting an outer surface of a wheel covered with evenly-spaced wheel treads to determine trajectory of the wheel, the optical sensor system comprising: a first optical sensor mounted in the wheel arch above the wheel for performing a plurality of counts corresponding to respectively capturing a plurality of images of the wheel according to the wheel treads; a first clear casing mounted in the wheel arch between the wheel and the first optical sensor, but not touching the wheel; a second optical sensor mounted in the wheel arch on one side of the wheel for performing a plurality of counts corresponding to respectively capturing a plurality of images of the wheel according to the wheel treads; a second clear casing mounted in the wheel arch between the wheel and the second optical sensor, but not touching the wheel; a third optical sensor mounted in the wheel arch on the other side of the wheel for performing a plurality of counts corresponding to respectively capturing a plurality of images of the wheel according to the wheel treads; and a third clear casing mounted in the wheel arch between the wheel and the third optical sensor, but not touching the wheel; wherein the captured images are compared with a reference image to determine a 2D displacement, a calculation is performed to convert the measured 2D displacement of the wheel from its original position into a distance the wheel travels along a path in order to determine the wheel trajectory, the wheel trajectory is determined by calculating a turning degree of the wheel according to a trigonometric manipulation of the captured 2D displacement, the calculated turning degree and at least a distance between a front wheel axle and a rear wheel axle of the car are utilized to determine a turning curve along which the wheel moves, the turning curve being centered on a point where an extended line from the rear axle crosses a perpendicular line to the front axle. ### Claim 2 (depends on 1) The optical sensor system of claim 1, wherein a calibration process is first performed by measuring a 2D displacement of the wheel corresponding to a single rotation of the wheel, determining how many counts are performed according to this single rotation, then utilizing a circumference of the wheel to determine a distance per count (dpc) value, wherein the dpc value is used to convert the measured 2D displacement into a distance the wheel travels along a path. ### Claim 3 (depends on 2) The optical sensor system of claim 2, wherein the calibration process is performed when the wheel rotates but does not turn. ### Claim 4 A method for using an optical sensor system mounted in a wheel arch in a car to count an outer surface of a wheel covered with evenly-spaced wheel treads to determine trajectory of the wheel, the method comprising: utilizing a first optical sensor mounted in the wheel arch above the wheel and behind a first clear casing which does not touch the wheel, a second optical sensor mounted in the wheel arch on one side of the wheel and behind a second clear casing which does not touch the wheel, and a third optical sensor mounted in the wheel arch on the other side of the wheel and behind a third clear casing which does not touch the wheel to perform the following steps: capturing a plurality of images of the wheel according to the wheel treads to generate a plurality of counts, respectively; comparing the captured images with a reference image to determine a 2D displacement of the wheel; and performing a calculation to convert the measured 2D displacement of the wheel from its original position into a distance the wheel travels along a path in order to determine the wheel trajectory, comprising: calculating a turning degree of the wheel according to a trigonometric manipulation of the captured 2D displacement; and utilizing the calculated turning degree and at least a distance between a front wheel axle and a rear wheel axle of the car to determine a turning curve along which the wheel moves, the turning curve being centered on a point where an extended line from the rear axle crosses a perpendicular line to the front axle. ### Claim 5 (depends on 4) The method of claim 4, wherein a calibration process is first performed comprising the following steps: measuring a 2D displacement of the wheel corresponding to a single rotation of the wheel; determining how many counts are performed according to this single rotation; and utilizing a circumference of the wheel to determine a distance per count (dpc) value; wherein the dpc value is used to convert the measured 2D displacement into a distance the wheel travels along a path. ### Claim 6 (depends on 5) The method of claim 5, wherein the calibration process is performed when the wheel rotates but does not turn.