Steering Column Position Determination Using Relative Sensors

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Vehicle steering systems face a cost constraint due to the use of absolute position sensors, necessitating a method to determine the absolute position of a vehicle steering column without relying on these expensive sensors.

Innovation Solution

A method that utilizes relative position sensors coupled to the steering assist motor to determine the absolute rotational position of the steering column by calculating rotational position offset values and storing them in a memory device, allowing for centering and position determination without the need for absolute position sensors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If an absolute position sensor is used to determine the absolute rotational position of the steering column, then the measurement precision is improved, but the device cost increases

Engineering Contradiction:

Improveabsolute rotational position measurementVSAvoiddevice cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent uses a relative position sensor to measure relative rotational positions and creates a computational model that copies the functionality of an absolute position sensor. By integrating relative position measurements over time and using mathematical transformations, the system reconstructs absolute position information without requiring an expensive absolute position sensor, thus achieving the measurement precision of an absolute sensor while avoiding its high cost.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent replaces the mechanical/electrical absolute position sensor with a computational approach. Instead of using a dedicated sensor that directly measures absolute position, the system uses a relative position sensor combined with software algorithms (integration, coordinate transformations, and reference frame changes) to calculate absolute position, substituting a mechanical sensing system with a computational one.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of manufacture

If a relative position sensor is used instead of an absolute position sensor, then the device cost is reduced, but the ability to determine absolute position directly is worsened

Engineering Contradiction:

Improvedevice costVSAvoidabsolute rotational position determination

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent performs preliminary calibration during system initialization to establish the relationship between the relative position sensor measurements and the actual absolute position. By pre-determining transformation parameters and reference frames during a calibration phase, the system prepares the necessary data structures and mathematical models in advance, enabling accurate absolute position calculation from relative measurements during normal operation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously integrates relative position measurements and uses feedback loops to maintain accuracy. By constantly updating the calculated absolute position based on accumulated relative measurements and comparing with expected values, the system compensates for drift and maintains measurement precision over time, ensuring that the derived absolute position remains accurate despite using only a relative position sensor.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS8375779B2Method for determining an absolute rotational position of a vehicle steering column

Publication Date: 2013.02.19 STEERING SOLUTIONS IP HOLDING CORP

AI summary

A method for determining an absolute rotational position of a vehicle steering column is provided. In one exemplary embodiment, the method determines a relative position of a steering assist motor utilizing a relative position sensor. Thereafter, the method determines the absolute rotational position of the vehicle steering column based upon the relative position of the steering assist motor.