Steering Roll Radius Adjustment for Vehicle Direction Control
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Solution Overview
Problem
Conventional redundant steering systems for motor vehicles are complex and expensive to implement, with limited ability to influence direction due to the design of scrub radius, which affects their reliability and functionality, especially in highly automated driving scenarios.
Innovation Solution
Adjusting the steering roll radius and applying a force component orthogonal to the direction of travel, such as through braking or actuator adjustments, to enhance the flexibility and redundancy of the steering system, allowing for more significant influence over the vehicle's direction even with a small force component, thereby supporting conventional steering systems like Ackermann steering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a redundant steering system is implemented by duplicating mechanical components, then reliability is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent combines the redundant steering function with the existing braking system. The braking system, which already exists in the vehicle, is repurposed to provide steering assistance by applying braking forces to steerable wheels. This merging eliminates the need for separate redundant mechanical steering components, thereby maintaining reliability while reducing device complexity and cost.
Solution Approach 2:
The braking system is given a dual function: its primary function remains vehicle deceleration, and its secondary function becomes steering assistance. By making the braking system universal, the patent eliminates the need for dedicated redundant steering components, resolving the contradiction between reliability and complexity.
2Power
If braking on one side of the vehicle is used for redundant steering, then steering assistance is provided, but the scrub radius limits the effectiveness of the yaw moment generation
Solution Approach 1:
The patent dynamically adjusts the scrub radius parameter by modifying the braking force distribution among wheels. By changing the braking parameters (force magnitude, distribution pattern, timing), the system overcomes the limiting effect of the fixed geometric scrub radius, enabling effective yaw moment generation despite the geometric constraint.
Solution Approach 2:
The system transitions from a static scrub radius constraint to a dynamic solution where braking forces are continuously adjusted. The braking system applies forces adaptively based on steering requirements, vehicle state, and road conditions, transforming the fixed geometric limitation into a controllable parameter that can be optimized in real-time.
3Stability of the object's composition
If the scrub radius is designed to be negative or slightly positive for comfort, then vehicle stability is improved, but the ability to generate significant steering or yaw moments through braking is reduced
Solution Approach 1:
The patent introduces asymmetry in the braking force application to overcome the symmetry of the vehicle's stable configuration. By applying different braking forces to different wheels (asymmetric braking distribution), the system generates the necessary yaw moments while maintaining the underlying stable vehicle geometry with negative or slightly positive scrub radius.
Solution Approach 2:
The system changes the operational parameters of the braking system (force distribution, application timing, intensity) to achieve steering effects without altering the fundamental vehicle geometry. This allows the vehicle to maintain its stable negative scrub radius configuration while still generating sufficient yaw moments through optimized braking parameter selection.
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
This approach enables a more flexible and economically viable redundant steering system that can effectively influence the direction of travel, ensuring redundancy and reliability even if the primary steering system fails, by generating a strong yawing moment and applying forces to the steering mechanism, thus maintaining control and stability.
Implementation Method 1
braking one or all wheels on one side of the vehicle
Implementation Method 2
generate a yaw moment by braking on one side of the vehicle
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a method for influencing the direction of travel of motor vehicles (2), the motor vehicle (2) comprising a first steering system (4) which in turn comprises at least one steering axle (3) with at least two wheels (6), the wheels (6) being connected to the steering axle (3) by wheel suspensions (7, 8) that can be adjusted by actuators. According to the invention, a redundant steering system is produced by adjusting a steering roller radius (RΦ) of at least one of the steering axles (3), whereafter a force component (FL) acting orthogonally to the direction of travel is applied to the first steering system (4) in the region of at least one wheel (6).