Steering Control Device Torque Switching

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Solution Overview

Problem

Existing steering control devices experience excessive steering torque during the switching from tracking control to assist control due to the cancellation of assist torque by automatic steering torque, leading to an abrupt change in steering torque during driver intervention.

Innovation Solution

A steering control device with an assist control calculation unit, a target tracking control calculation unit, an intervention detection unit, and a limit value calculation unit that reduces the absolute value of the tracking command limit value in response to the assist command, preventing excessive steering torque by inhibiting the tracking command from obstructing the steering during control switching from tracking to assist control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If tracking control is performed by generating automatic steering torque to cause detection value to track target value, then lane keeping capability is improved, but excessive steering torque occurs during switching to assist control due to cancellation of assist torque by automatic steering torque

Engineering Contradiction:

Improvelane keeping capabilityVSAvoidexcessive steering torque during control switching

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The limit value calculation unit preemptively reduces the tracking command limit value when assist control is activated, creating a counteracting effect that prevents the harmful cancellation between assist torque and automatic steering torque. This preliminary action occurs before the excessive torque can fully manifest, thereby resolving the contradiction between maintaining lane keeping capability and preventing excessive steering torque during switching.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The system dynamically adjusts the tracking command limit value based on the control mode. During assist control, the limit value is reduced to allow smooth transition, while during pure tracking control, the full limit value is maintained to ensure effective lane keeping. This dynamic adaptation resolves the contradiction by optimizing the tracking command behavior for each specific operational context.

Inventive Principle:

Principle #15Dynamics

2Extent of automation

If tracking command is generated to cause detection value to track target value, then automatic steering performance is improved, but abrupt change in steering torque occurs during driver intervention

Engineering Contradiction:

Improveautomatic steering performanceVSAvoidsteering smoothness during driver intervention

Core Design Contradiction:

Extent of automationVSEase of operation

Solution Approach 1:

The limit value calculation unit preemptively reduces the tracking command limit value upon detecting assist control activation, creating a counteracting effect that prevents abrupt steering torque changes. This preliminary action occurs before the driver's steering input fully manifests, thereby resolving the contradiction between maintaining automatic steering performance and ensuring steering smoothness during driver intervention.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The system applies a cushioning effect by reducing the tracking command limit value before the driver's steering input can cause abrupt torque changes. This beforehand cushioning prevents the harmful interaction between automatic steering torque and driver input, ensuring smooth transition while preserving the benefits of automatic steering control.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Ease of operation

If assist torque is generated based on steering torque during assist control, then steering assist capability is improved, but steering torque becomes excessive when canceled by automatic steering torque during switching

Engineering Contradiction:

Improvesteering assist capabilityVSAvoidsteering torque magnitude during control switching

Core Design Contradiction:

Ease of operationVSForce

Solution Approach 1:

The limit value calculation unit preemptively reduces the tracking command limit value when assist control is activated, creating a counteracting effect that prevents the harmful cancellation between assist torque and automatic steering torque. This preliminary action occurs before the excessive torque can fully manifest, thereby resolving the contradiction between maintaining steering assist capability and preventing excessive steering torque during switching.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The system dynamically adjusts the tracking command limit value based on the control mode. During assist control, the limit value is reduced to prevent excessive torque generation, while during pure tracking control, the full limit value is maintained to ensure effective lane keeping. This dynamic adaptation resolves the contradiction by optimizing the torque behavior for each specific operational context.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS12024241B2Steering control device

Publication Date: 2024.07.02 DENSO CORP

AI summary

A steering control device performs an assist control for generating an assist command that generates an assist torque based on a steering torque. The steering control device acquires a target value of physical quantity related to a steering. The steering control device performs a tracking control for generating a tracking command that generates an automatic steering torque for causing a detection value of physical quantity to track the target value.