Steering Torque Estimation via Bank Angle and Wheel Speed

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Solution Overview

Problem

The existing systems for detecting steering torque in vehicles that turn in a banked state are costly due to the need for additional components and complex sensor placement, which complicates design and manufacturing.

Innovation Solution

A steering torque estimating device that calculates steering torque based on changes in bank angle, rotational speed, braking force, vertical force, lateral force, and slip angle, using a processor unit to estimate torque components and output accurate steering torque values.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a torque sensor is attached on the vehicle body to detect steering torque, then steering torque detection is achieved, but manufacturing cost increases and design becomes complex

Engineering Contradiction:
Improvesteering torque detectionVSAvoidsensor space and component arrangement
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical torque sensor with a calculation-based estimation system. The steering torque is computed using the relationship between braking force, front wheel vertical force, lateral force, and geometric parameters (bank angle, trail, caster angle) rather than direct mechanical measurement. This substitution eliminates the need for physical sensor installation on the vehicle body.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces intermediate calculation parameters (braking force, vertical force, lateral force, bank angle) as mediators to indirectly determine steering torque. Instead of directly measuring torque at the steering axis, the system measures or calculates these intermediate forces and uses them in a computational model to derive the steering torque value.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If a torque sensor is attached on the vehicle body to detect steering torque, then steering torque detection is achieved, but manufacturing cost increases

Engineering Contradiction:
Improvesteering torque detectionVSAvoidmanufacturing cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces the mechanical torque sensor with a calculation-based estimation system. The steering torque is computed using the relationship between braking force, front wheel vertical force, lateral force, and geometric parameters (bank angle, trail, caster angle) rather than direct mechanical measurement. This substitution eliminates the need for physical sensor installation on the vehicle body.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses readily available data from existing vehicle systems (braking force sensors, wheel speed sensors, bank angle sensors) that are already part of the vehicle's standard equipment. By leveraging these existing components rather than adding dedicated expensive torque sensors, the system achieves cost-effective steering torque estimation.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Measurement precision

If components are added to detect steering torque, then measurement capability is improved, but design and manufacture of constituents near head pipe become complex

Engineering Contradiction:
Improvesteering torque measurementVSAvoiddesign and manufacture complexity
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces the mechanical torque sensor with a calculation-based estimation system. The steering torque is computed using the relationship between braking force, front wheel vertical force, lateral force, and geometric parameters (bank angle, trail, caster angle) rather than direct mechanical measurement. This substitution eliminates the need for physical sensor installation on the vehicle body.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP3530558B1Steering torque estimation device and method
Publication Date: 2021.12.01 KAWASAKI JUKOGYO KK
  • EP3530558B1 patent drawingFigure 1
  • EP3530558B1 patent drawingFigure 2A~2C
  • EP3530558B1 patent drawingFigure 3

AI summary

A steering torque estimating device which estimates steering torque which is torque provided to a steering axis due to a vehicle body behavior, in a vehicle including a front wheel as a steered wheel, the vehicle being configured to turn in a bank state in which a vehicle body is tilted around a forward-rearward axis, includes a torque estimating section which estimates the steering torque based on a change over time of a bank angle and a rotational speed of the front wheel.