Lane Keep Control Torque Smoothing During Driver-Initiated Lane Changes

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Solution Overview

Problem

Conventional lane keep control devices cause discomfort to drivers due to sudden changes in control torque when a vehicle enters an adjacent lane during a lane change, as the control torque increases to return the vehicle to the target path, opposing the driver's steering direction.

Innovation Solution

The lane keep control device reduces control strength when a lane change intention is detected, using gain maps to adjust the control torque based on lateral position deviation, minimizing discomfort by gradually reducing torque as the vehicle deviates from the target path before entering the adjacent lane.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the target path is reset when the vehicle enters the adjacent lane, then the vehicle can be returned to the target path, but the control torque changes greatly causing driver discomfort

Engineering Contradiction:

Improvevehicle return to target pathVSAvoiddriver discomfort

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system detects lane change intention in advance (when turn signal is activated) and preemptively reduces control strength before the vehicle actually enters the adjacent lane. This preliminary action prevents the sudden control torque change that would occur at lane entry, thereby reducing driver discomfort while still maintaining the ability to return the vehicle to the target path after the lane change is completed

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control strength is made dynamic by adjusting it based on the detected lane change intention. The system transitions from a static control strength to a dynamic one that varies according to the driving situation, reducing control strength when lane change is intended and maintaining normal control strength when no lane change is intended. This dynamic adjustment smooths the control torque changes and reduces driver discomfort

Inventive Principle:

Principle #15Dynamics

2Reliability

If the target steering angle increases to return the vehicle to the target path, then the lane keep control function is effective, but the control torque applied opposes the driver's steering direction causing discomfort

Engineering Contradiction:

Improvelane keep control effectivenessVSAvoiddriver discomfort

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system applies partial control action by reducing the control strength when lane change intention is detected. Instead of applying full control torque to return the vehicle to the target path, the system applies a reduced control torque that is sufficient to assist the lane change but does not oppose the driver's steering direction excessively. This partial action maintains lane keep control effectiveness while reducing driver discomfort

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS20250319869A1Lane keep control device, lane keep control method, and storage medium

Publication Date: 2025.10.16 TOYOTA JIDOSHA KK

AI summary

A lane keep control device performs lane keep control for controlling lateral movement of the vehicle so that the vehicle travels on a target path set in the own lane in which the vehicle is traveling. Further, when the lane change intention of the driver to change the lane is detected, the lane keep control device weakens the control strength of the lane keep control as the vehicle moves away from the target path as compared with a case where the lane change intention is not detected.