ABS Steering-Axle Mode Switching for Steer-by-Brake Stability
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Solution Overview
Problem
Highly automated vehicles with electrically controllable steering systems face challenges when these systems fail, as existing methods do not effectively provide a reliable fallback for maintaining vehicle control and steering, especially under varying friction conditions.
Innovation Solution
A method and device for an anti-lock braking system control unit that activates a 'steer-by-brake' function, allowing harmonious steering by setting a control mode to balance braking torques between wheels, using a common mode for pneumatic control valves and adjusting target slip values to minimize steering torques and yaw moments, thereby ensuring stable vehicle control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If individual brake pressure control is used for each wheel based on individual grip conditions, then braking effectiveness is improved, but steering torque and yaw moment increase causing unstable vehicle behavior
Solution Approach 1:
The patent segments the brake pressure control into two independent control channels: one channel controls brake pressure based on individual wheel grip conditions to ensure braking effectiveness, while the other channel separately controls steering torque and yaw moment to maintain vehicle stability. This segmentation allows both braking effectiveness and vehicle stability to be optimized simultaneously without interference.
2Stability of the object's composition
If brake pressure is reduced to minimize steering torque, then vehicle stability is improved, but braking distance increases
Solution Approach 1:
The patent changes the control parameters by introducing independent control of brake pressure, steering torque, and yaw moment through separate control channels. This allows the system to optimize brake pressure for maximum braking effectiveness while simultaneously adjusting steering torque and yaw moment parameters to maintain vehicle stability, achieving both short braking distance and stable vehicle behavior.
3Measurement precision
If electrically controllable steering system is used, then steering precision is improved, but system reliability deteriorates when steering components fail
Solution Approach 1:
The patent prepares compensatory measures in advance by enabling the ability to generate steering torque through brake pressure differential when the electrically controllable steering system fails. This beforehand cushioning ensures that even if the primary steering system fails, the vehicle can still be steered using the brake-based steering torque generation capability, thus maintaining reliability.
Data Source
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AI summary
The invention relates to a method for operating an anti-lock braking system control unit (110) for a highly automated vehicle (100) with at least one steering axle (105), having a reading step and a transmission step. In the reading step, an activation signal (135) is read which represents an activated steering brake function of the vehicle (100) and/or a deactivated electrically actuatable steering function of the vehicle (100). In the transmission step, a control signal (140) is transmitted using the activation signal (135) or in response thereto, said control signal being designed to set a control mode (145) for controlling an ABS function of the anti-lock braking system control unit (110) for at least the steering axle (105) of the vehicle (100).