Lane Departure Suppression Pre-control Torque Strategy

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Solution Overview

Problem

Existing lane departure suppression devices generate assist torque too late, leading to driver discomfort and increased likelihood of the car departing from its lane, as they start operating only when the torque exceeds the friction torque of the steering angle change mechanism, which can result in premature movement and discomfort for the driver.

Innovation Solution

A lane departure suppression device with a pre-control unit that generates a pre-control signal to gradually increase assist torque to or below the friction torque level before reaching the deflection starting position, ensuring that the assist torque is already active when the main control signal is output, allowing immediate steering angle change and preventing lane departure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the assist torque is generated only when the car reaches the deflection starting position (after exceeding friction torque), then the steering angle change mechanism can operate effectively, but the car may depart from the lane before the assist torque takes effect

Engineering Contradiction:

Improvelane departure suppression effectivenessVSAvoidresponse time for assist torque generation

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The pre-control unit generates assist torque before the car reaches the deflection starting position, preparing the steering angle change mechanism in advance. This preliminary action ensures that when the main control signal is output, the assist torque is already active or can immediately exceed the friction torque, preventing lane departure without delay.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The pre-control unit applies a small assist torque that counteracts the friction torque of the steering angle change mechanism before deflection is needed. This preliminary anti-action reduces the resistance that would otherwise delay the response when main control is activated, ensuring immediate effectiveness.

Inventive Principle:

Principle #9Preliminary anti-action

2Speed

If the assist torque is generated early to overcome friction torque, then the steering angle change mechanism operates promptly, but the driver experiences discomfort due to premature car movement

Engineering Contradiction:

Improveresponse speed of steering angle change mechanismVSAvoiddriver discomfort

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The pre-control unit applies assist torque only in the specific condition where the car position is between the pre-control start position and the deflection starting position. This localized application of torque ensures that the steering mechanism is prepared without causing premature car movement that would discomfort the driver.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The system changes the magnitude of assist torque based on the car's position. During pre-control, a small torque (equal to or less than friction torque) is applied to prepare the mechanism. When the car reaches the deflection starting position, the torque increases to the main control amount, ensuring smooth and comfortable operation.

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If the assist torque is set equal to or less than the friction torque during pre-control, then the steering angle change mechanism is prepared without causing car deflection, but the mechanism may not respond immediately when main control is activated

Engineering Contradiction:

Improvesmoothness of steering operationVSAvoidresponsiveness of steering angle change mechanism

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The pre-control unit continuously generates assist torque equal to or less than the friction torque, maintaining the steering angle change mechanism in a prepared state. This continuous preliminary action ensures that when the main control signal is output, the mechanism can immediately respond by exceeding the friction torque and activating the assist torque for deflection.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS10780916B2Lane departure suppression device

Publication Date: 2020.09.22 DENSO CORP

AI summary

A lane departure suppression device is provided in a car equipped with a steering angle change mechanism that changes a steering angle and with a motor that operates the steering angle change mechanism, and the lane departure suppression device includes: a main control unit that outputs a main control signal after a position of the car reaches a deflection starting position at which deflection of the car is started in order to suppress departure of the car from a lane, the main control signal representing a main control amount for causing the motor to generate an assist torque that changes the steering angle; and a pre-control unit that outputs, until the main control unit outputs the main control signal, a pre-control signal while the position of the car is located closer to a center of the lane than the deflection starting position is, the pre-control signal representing a pre-control amount for causing the motor to generate an assist torque equal to or less than a friction torque of the steering angle change mechanism.