Front Axle Steering Centering via Wheel-Selective Braking
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Solution Overview
Problem
Existing motor vehicles with piloted driving systems face challenges in maneuvering and direction control when the front axle steering system fails, especially at high speeds, as simply adjusting the rear axle steering angle is insufficient to significantly influence vehicle maneuvering and direction.
Innovation Solution
Implementing a device for automatic centering of the front axle steering system using wheel-selective brake interventions, independent of the front steering angle, to compensate for lateral tire forces and enable rear axle steering system takeover, with active centering and defined transition periods for maintaining vehicle control within a driving lane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rear axle steering system is used to take over steering control when the front axle steering system fails, then steering functionality is maintained, but the vehicle cannot be effectively maneuvered at high speeds because simply adjusting the rear axle steering angle is insufficient to influence vehicle maneuvering and direction
Solution Approach 1:
The patent combines the rear axle steering system with wheel-selective brake interventions and active centering of the front axle steering system to create a composite steering control mechanism. This merging allows the rear axle steering to effectively influence vehicle maneuvering at high speeds by coordinating multiple systems rather than relying on rear axle steering alone.
Solution Approach 2:
The wheel-selective brake interventions act as an intermediary mechanism between the rear axle steering system and the vehicle's motion. The brakes provide the necessary lateral forces to compensate for the side slip angle, enabling the rear axle steering to effectively control vehicle direction and maneuvering capability.
2Ease of operation
If wheel-selective brake interventions are used to compensate for lateral tire forces and enable rear axle steering takeover, then effective vehicle maneuvering is achieved, but the system complexity increases due to the need for active centering and coordinated brake interventions
Solution Approach 1:
The wheel-selective brake intervention system serves multiple functions: it compensates for lateral tire forces, enables rear axle steering takeover, and provides active centering of the front axle steering system. This multi-functionality reduces the need for separate dedicated components for each function, thereby managing system complexity while achieving effective vehicle maneuvering.
Solution Approach 2:
The active centering of the front axle steering system operates autonomously to maintain proper wheel alignment without requiring manual intervention. The system self-adjusts the front axle steering angle to compensate for side slip angle effects, reducing the burden on the driver and simplifying the overall control strategy.
3Manufacturing precision
If active centering of the front axle steering system is carried out independently of the side slip angle, then proper wheel alignment is maintained, but the transition time period is extended during which the vehicle is controlled in a side strip of the driving lane
Solution Approach 1:
The active centering of the front axle steering system is activated in advance during the transition period to ensure proper wheel alignment is established before the vehicle needs to be fully maneuvered. This preliminary action ensures that when the rear axle steering system takes over, the front wheels are already properly aligned, reducing the overall transition time despite the additional centering operations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables effective maneuvering and direction control of the vehicle during piloted driving by compensating for side slip angles through wheel-selective brake interventions, ensuring safe transition and deceleration within a driving lane even when the front axle steering system fails.
Implementation Method 1
The wheel-selective brake interventions are used to provide compensation for the lateral force of the tires that is created due to the side slip angle of the vehicle
Data Source
AI summary
A motor vehicle for piloted driving including a front axle steering system and a rear axle steering system. In the active, trouble-free driving state with a piloted driving, the driving task for steering the front axle is performed by a front axle steering control which automatically controls the front axle steering system. A failure of the automatic front axle steering control is automatically recognized with a failure recognition device and the vehicle steering is taken over by the rear axle steering system. The motor vehicle is equipped with a device for controlled wheel-selective brake intervention. In case of a failure of the automatic front axle steering control, this device is controlled in such a way that an automatic centering of the front axle steering system is performed by wheel-selective braking interventions.