Optical Steering Shaft Angle Sensing Without Magnetic Interference

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Solution Overview

Problem

Existing vehicle steering angle measurement systems, such as those using hall effect sensors with magnets, suffer from limited response time and accuracy.

Innovation Solution

A non-contact system utilizing a rotatable steering shaft, a radially spaced reflector, and emitters/receivers to measure steering angle by detecting the time between light emission and receipt, with the reflector reflecting light between the shaft and emitters/receivers to determine the angle.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If hall effect sensors with magnets are used to measure steering angle, then the system can measure steering angle, but the response time and accuracy are limited

Engineering Contradiction:

Improvesteering angle measurement accuracyVSAvoidresponse time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces the mechanical/magnetic hall effect sensor system with an optical measurement system using emitters, receivers, and reflectors. This substitution eliminates magnetic field interference and mechanical contact issues, achieving faster response times and higher measurement accuracy for steering angle detection.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces reflectors as intermediary elements between the emitters and receivers. These reflectors are positioned on the steering shaft and redirect light signals to provide precise angular position information, enabling accurate steering angle measurement through optical path modulation rather than direct magnetic sensing.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If hall effect sensors with magnets are used, then steering angle can be measured, but magnetic field interference limits reliability

Engineering Contradiction:

Improvesystem reliabilityVSAvoidmagnetic field interference

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the magnetic field-based hall effect sensing with an optical sensing system using emitters and receivers. This eliminates susceptibility to magnetic field interference from vehicle electronics and external sources, significantly improving system reliability and consistency in various operating conditions.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent removes magnets and magnetic sensing components from the steering angle measurement system. By extracting the magnetic field dependency entirely, the system becomes immune to magnetic interference while maintaining the ability to measure steering angle through optical means.

Inventive Principle:

Principle #2Taking out (Extraction)

3Measurement precision

If non-contact optical system with emitters and receivers is used, then response time and accuracy improve, but device complexity increases

Engineering Contradiction:

Improvesteering angle measurement accuracyVSAvoidsystem complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent positions the reflectors on the steering shaft within the existing steering column structure, nesting the optical measurement components within the mechanical steering system. This integration minimizes additional space requirements and reduces overall system complexity while achieving high measurement precision.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The optical components (emitters, receivers, and reflectors) serve multiple functions: they measure steering angle position, detect steering shaft rotation, and provide feedback for control systems. This multi-functionality reduces the need for separate sensing systems, thereby managing device complexity while improving measurement capabilities.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 fast and accurate determination of steering angle and its change, improving steering control without the interference of magnetic fields, and enhancing system reliability and accuracy.

Implementation Method 1

the reflector includes a radially inner surface and the inner surface is arranged to reflect light emitted from the emitter

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

The time between an emission of light from the emitter and receipt of light by the receiver is indicative of the steering angle

Methodology Applied

Scientific EffectTime of flight: Time of Flight

Data Source

PatentUS20260029254A1Non-contact measurement of a vehicle steering angle

Publication Date: 2026.01.29 FCA US LLC

AI summary

A system for measuring steering angle and a change of steering angle in a vehicle includes a steering shaft that is rotatable to change a steering angle of a vehicle, a reflector arranged radially spaced from a surface of the steering shaft, wherein the steering shaft is rotatable relative to the reflector, an emitter that emits light, and a receiver that receives light emitted from the emitter. Either the emitter or the receiver is carried by the steering shaft for rotation with the steering shaft, and the other of the emitter or receiver does not rotate with the steering shaft such that rotation of the steering shaft causes relative movement between the emitter and the reflector. The time between an emission of light from the emitter and receipt of light by the receiver is indicative of the steering angle.