Vehicle Steering System Dynamic Torque Threshold for Driver Intervention

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Solution Overview

Problem

Existing vehicle steering systems during automatic parking control often cause discomfort due to rapid steering wheel rotation, leading to unexpected impacts on the driver's hands or fingers, as the intervention in automatic steering control is not properly managed according to the vehicle's operating speed and driving state.

Innovation Solution

A vehicle steering system that includes a steering actuator, an automatic steering controller, a driving state detector, and a threshold value setting unit to variably set intervention thresholds based on the vehicle's driving state, allowing for proper intervention in automatic steering control, including torque and speed adjustments to prevent discomfort and improve steering feel.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the steering wheel rotates fast to achieve quick parking positioning, then the parking efficiency is improved, but the driver may feel discomfort or injury from abrupt impacts

Engineering Contradiction:

Improveparking efficiencyVSAvoiddriver discomfort

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the parameter of torque threshold dynamically based on steering angular velocity. When steering angular velocity exceeds a threshold, the torque threshold is reduced, allowing the system to respond to driver intervention at lower torque levels during high-speed steering operations, thereby preventing driver discomfort while maintaining parking efficiency

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements feedback by continuously monitoring steering angular velocity and adjusting the torque threshold accordingly. The ECU detects the steering angular velocity and uses this information to dynamically set the torque threshold, creating a closed-loop control system that adapts to real-time operating conditions

Inventive Principle:

Principle #23Feedback

2Device complexity

If a fixed torque threshold is used for intervention detection, then the control logic is simple, but the intervention detection is not accurate under varying driving conditions

Engineering Contradiction:

Improvecontrol logic complexityVSAvoidintervention detection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent makes the torque threshold dynamic rather than fixed. The threshold is adjusted based on steering angular velocity, allowing the system to adapt to varying driving conditions. This dynamic adjustment improves intervention detection accuracy without requiring overly complex control logic

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the torque threshold parameter based on steering angular velocity. By linking the threshold to a measurable operational parameter, the system achieves accurate intervention detection across different driving conditions while maintaining relatively simple control logic

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS7516003B2Vehicle steering system

Publication Date: 2009.04.07 JTEKT CORP

AI summary

A vehicle steering system includes: a steering actuator that imparts a steering force to a steering mechanism of a vehicle; an automatic steering controller that performs an automatic steering control by controlling the steering actuator; a driving state detector that detects a driving state of the vehicle during the automatic steering control; a threshold value setting unit that variably sets a threshold value for permitting an intervention in the automatic steering control; and an automatic steering intervention unit that intervenes in the automatic steering control based on a threshold value set by the threshold value setting unit.