Wheel-Arch Optical Odometry for Wheel Trajectory Tracking
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Solution Overview
Problem
Existing optical sensors are limited in tracking motion over larger distances and complex paths, particularly when used in applications involving wheels, as they require multiple sensors and struggle to accurately convert 2D displacement into real-life distance and trajectory.
Innovation Solution
An optical sensor system mounted in a car's wheel arch, utilizing two sensors to capture images of the wheel, compare them to a reference image, and perform trigonometric calculations to determine 2D displacement, which is then converted into distance traveled and trajectory, with a calibration process to establish a distance per count value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single optical sensor is used to track wheel motion, then device complexity is reduced, but measurement precision deteriorates due to inability to accurately determine both 2D displacement and angular orientation
Solution Approach 1:
The patent applies dimensionality change by transitioning from 2D image plane coordinates to 3D spatial trajectory. The optical sensor captures 2D images of the wheel and uses trigonometric manipulation to calculate 3D trajectory parameters including distance traveled and turning angle. This allows a single sensor to determine both linear displacement and angular orientation by mathematically reconstructing the wheel's motion path from 2D image sequences.
2Adaptability or versatility
If optical sensors are used for large distance tracking, then applicability expands, but measurement precision deteriorates due to accumulation of errors over longer distances
Solution Approach 1:
The patent replaces traditional mechanical odometry systems (which rely on wheel encoders and direct measurement) with an optical imaging system. The optical sensor captures images of the wheel at regular intervals, and trajectory is determined through image comparison and trigonometric calculations rather than mechanical counting. This substitution allows for longer tracking distances while maintaining precision by continuously re-establishing the reference frame through image processing.
3Measurement precision
If the sensor is positioned close to the wheel for better image capture, then measurement precision improves, but the sensor becomes vulnerable to wheel contact and damage
Solution Approach 1:
The patent introduces a clear protective casing as an intermediary between the optical sensor and the wheel. This transparent enclosure allows optical signals to pass through while physically protecting the sensor from wheel contact, debris, and environmental factors. The casing acts as a mediator that maintains both measurement precision (by preserving optical clarity) and sensor safety (by providing physical protection).
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate determination of wheel trajectory and distance traveled, allowing for precise odometry tracking with a single optical sensor, capable of handling both straight and turning motions, and adaptable to various terrains by compensating for changes in sensor distance.
Implementation Method 1
Optical sensors work by illuminating the surface on which the object moves to capture an image
Data Source
AI summary
An optical sensor system mounted in a wheel arch of a car for determining trajectory of the car includes: a first optical sensor mounted in the wheel arch above a wheel and located behind a first clear casing that does not touch the wheel; and a second optical sensor mounted in the wheel arch on one side of the wheel and located behind a second clear casing that does not touch the wheel. The first optical sensor and second optical sensor perform a plurality of counts corresponding to respectively capturing a plurality of images of the wheel. The captured images are compared with a reference image to determine a 2D displacement of the wheel from its original position. The trajectory of the car is determined by calculating a turning degree of the wheel according to a trigonometric manipulation of the measured 2D displacement.