Automatic Steering Takeover Using Integrated Torque Detection

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Solution Overview

Problem

Existing automatic steering control systems cause driver discomfort due to slow or unintended cancellation of automatic steering when the driver applies steering torque exceeding a threshold, leading to delays in switching to manual control.

Innovation Solution

An automatic steering control system that integrates steering torque over a predetermined period and switches to manual steering when an integration threshold is exceeded, reducing the likelihood of discomfort by ensuring timely transitions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a predetermined steering torque threshold is used to determine when to cancel automatic steering, then the system responds to driver input, but the cancellation is delayed causing driver discomfort

Engineering Contradiction:

Improveaccuracy of driver intent detectionVSAvoidresponse time for switching to manual steering

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary integration of steering torque values over a predetermined time period before making the cancellation decision. This preliminary action accumulates evidence of driver intent over time, allowing the system to distinguish between transient torque fluctuations and genuine driver takeover intentions, thereby reducing false cancellations while maintaining timely response.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The integration value serves as an intermediary parameter between the raw steering torque input and the automatic steering cancellation decision. By introducing this intermediate integration step, the system smooths out noise in the torque signal and provides a more reliable basis for determining driver intent, resolving the contradiction between sensitivity and false activation.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Speed

If the steering torque threshold is set low to detect driver intent quickly, then response time improves, but unintended cancellation increases causing discomfort

Engineering Contradiction:

Improvespeed of switching to manual steeringVSAvoidunintended cancellation of automatic steering

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The system accumulates steering torque values over a predetermined time period before triggering cancellation, performing a preliminary integration action. This allows the system to use a lower effective threshold while maintaining reliability, as the integration process filters out transient fluctuations that would cause unintended cancellations with simple threshold comparison.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The integration process provides beforehand cushioning against false cancellation by accumulating torque evidence over time. This cushioning effect prevents transient torque spikes from triggering unintended cancellation, while still allowing genuine driver intent to be detected when sustained torque is applied.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS12559171B2Automatic steering control apparatus, automatic steering control method, and non-transitory recording medium

Publication Date: 2026.02.24 SUBARU CORP

AI summary

An automatic steering control apparatus includes a steering torque detector and a steering processor. The steering torque detector is configured to detect a steering torque amount applied to a steering shaft of a vehicle. The steering processor is configured to switch between an automatic steering and a manual steering. The steering processor is configured to calculate an integration value in which the steering torque amount detected by the steering torque detector is integrated for a predetermined period, and switch the automatic steering to the manual steering when the integration value exceeds an integration threshold.