Vehicle Steering Backup Control for Front Wheel Failure

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Solution Overview

Problem

The existing steering-by-wire systems in autonomous vehicles fail to ensure safe steering when the front wheel steering capability is lost, posing serious safety hazards, especially at lower vehicle speeds.

Innovation Solution

A steering control method and system that monitors the steering capability of front wheels, selects a preset vehicle speed threshold based on the failure degree of the steering capability, and determines additional steering using rear wheel steering, roll steering, and vector torque steering to compensate for the lost front wheel steering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Extent of automation

If steering-by-wire system is used for autonomous vehicle steering control, then automation level is improved, but reliability deteriorates when steering failure occurs

Engineering Contradiction:
Improvesteering automationVSAvoidsteering safety
Core Design Contradiction:
Extent of automationVSReliability

Solution Approach 1:

The system establishes multiple backup steering schemes (rear wheel steering, roll steering, vector torque steering) in advance that can be activated when front wheel steering fails. These backup schemes are prepared beforehand to cushion the impact of steering-by-wire system failure, ensuring continuous steering capability even when the primary steering system fails.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The system dynamically changes steering parameters by selecting different vehicle speed thresholds based on the degree of steering capability failure. When partial failure occurs, a first vehicle speed threshold is used; when complete failure occurs, a second vehicle speed threshold is used. This parameter adaptation allows the system to optimize backup steering activation conditions according to the actual failure state.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If additional steering methods are activated to compensate for front wheel steering failure, then reliability is improved, but device complexity increases

Engineering Contradiction:
Improvesteering safetyVSAvoidsteering system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system makes existing vehicle components (rear wheels, suspension system, drive/brake systems) perform multiple functions. The rear wheels not only provide propulsion but also serve as a backup steering mechanism. The suspension system not only supports vehicle weight but also provides roll steering capability. The drive and brake systems not only control vehicle speed but also provide vector torque steering. This multi-functionality approach improves steering reliability without requiring additional dedicated steering components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system uses the vehicle's own existing systems (rear wheel steering capability, active suspension, drive and brake systems) to compensate for front wheel steering failure, rather than requiring external or additional specialized components. The vehicle essentially serves itself by utilizing its existing multi-functional capabilities to maintain steering control when the primary steering system fails.

Inventive Principle:
Principle #25Self-service

3Reliability

If vehicle speed threshold is lowered to enable backup steering activation, then steering safety is improved, but energy consumption increases

Engineering Contradiction:
Improvesteering safetyVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system dynamically adjusts the vehicle speed threshold parameter based on the degree of steering capability failure. When partial failure occurs, a higher first vehicle speed threshold is used to limit backup steering activation to lower speeds only. When complete failure occurs, a lower second vehicle speed threshold is used to allow broader activation conditions. This adaptive parameter adjustment ensures backup steering is activated only when necessary and appropriate, balancing safety with energy efficiency.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The system applies partial action by not always activating all backup steering methods. Instead, it selectively activates specific backup steering schemes based on the comparison between current vehicle speed and the applicable threshold, and based on the degree of steering capability failure. This partial activation approach avoids unnecessary energy consumption while ensuring safety when truly needed.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP4378788B1Steering control method and system for vehicle, related apparatus, and vehicle
Publication Date: 2025.04.23 NIO TECH ANHUI CO LTD
  • EP4378788B1 patent drawingFigure 1~3

AI summary

The disclosure provides a steering control method and system (100) for a vehicle, a related apparatus, and a vehicle. The steering control method comprises: monitoring a steering capability state of front wheels of the vehicle; if the steering capability of the front wheels of the vehicle fails, selecting a preset vehicle speed threshold according to the failure degree of the steering capability of the front wheels of the vehicle; and determining additional steering used to compensate for front wheel steering by comparing a current vehicle speed and the vehicle speed threshold, the additional steering comprises one or more of additional rear wheel steering, additional roll steering by adjusting a vehicle roll angle, and vector torque steering by adjusting longitudinal forces for the wheels.