Tag Axle Steering Fail-Safe Control for Oversteer Prevention

Solution Overview

Problem

Existing tag axle steering systems in vehicles face safety limitations and maneuverability issues due to potential malfunctions, particularly at higher speeds, leading to unsafe oversteering behaviors and increased tyre wear.

Innovation Solution

A method and control device that locks tag axle wheels at their current steering angle upon detecting a malfunction, allowing safe failure mode operation, and transitions to caster steer mode when conditions permit, ensuring safe vehicle behavior and reducing tyre wear.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the tag axle steering system is deactivated at high vehicle speeds, then safety is improved, but maneuverability is reduced

Engineering Contradiction:

ImprovesafetyVSAvoidmaneuverability

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent applies dynamics by making the fail-safe state configurable based on vehicle speed. At lower speeds, the system transitions to caster steering mode for maneuverability, while at higher speeds it locks the tag axle wheels for safety. This dynamic adjustment of system behavior based on operating conditions resolves the contradiction between safety and maneuverability.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the operational parameter of the tag axle steering system based on vehicle speed. The control device monitors speed and adjusts the fail-safe state accordingly - locking wheels at neutral position for high speeds, allowing caster steering for low speeds. This parameter change enables the system to optimize both safety and maneuverability across different operating ranges.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the tag axle wheels are locked in neutral position upon malfunction, then safety is improved, but unwanted oversteering behavior may occur during turning

Engineering Contradiction:

ImprovesafetyVSAvoidvehicle behavior predictability

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent applies dynamics by making the fail-safe state configurable based on vehicle speed. At lower speeds, the system transitions to caster steering mode for maneuverability, while at higher speeds it locks the tag axle wheels for safety. This dynamic adjustment of system behavior based on operating conditions resolves the contradiction between safety and maneuverability.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the operational parameter of the tag axle steering system based on vehicle speed. The control device monitors speed and adjusts the fail-safe state accordingly - locking wheels at neutral position for high speeds, allowing caster steering for low speeds. This parameter change enables the system to optimize both safety and maneuverability across different operating ranges.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If the tag axle steering system uses conventional locking mechanisms, then system complexity is reduced, but tyre wear increases

Engineering Contradiction:

Improvesystem complexityVSAvoidtyre wear

Core Design Contradiction:

Device complexityVSLoss of substance

Solution Approach 1:

The patent applies self-service by utilizing the vehicle's existing suspension system to automatically center the tag axle wheels when the steering system malfunctions. The suspension springs and dampers naturally exert restoring forces on the wheel assembly, eliminating the need for additional active centering mechanisms and reducing tyre wear from artificial locking.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent extracts the active centering function from the steering system and relies on the passive suspension system to provide the centering effect. By removing the need for complex active locking and centering mechanisms, the system reduces complexity while minimizing tyre wear through natural suspension-based centering.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS12473021B2Control device and method for controlling a tag axle steering system

Publication Date: 2025.11.18 SCANIA CV AB

AI summary

A control device and method for controlling a tag axle steering system, configured to steer tag axle wheels of a tag axle, are provided. The method comprises, when the steering angle of the tag axle wheels is offset from a steering angle of a neutral position of the tag axle wheels and in response to a fault signal indicating malfunction of the tag axle steering system, locking the position of the tag axle wheels at a current steering angle of the tag axle wheels. A computer program and a computer-readable medium, as well as a vehicle, are also disclosed.