ABS Brake Torque Control Using Wheel Acceleration Feedback
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Solution Overview
Problem
Existing antilock brake systems face challenges in rapidly and reliably preventing wheel locking during braking, especially at varying road conditions and low vehicle speeds, due to the complexity in applying a consistent and adaptive reduction in braking torque.
Innovation Solution
The method involves cyclically controlling braking torque by increasing it during build-up phases until maximum adhesion is reached and then reducing it using a differential braking torque calculated from measured wheel acceleration values and target acceleration values, allowing for rapid re-acceleration of the wheel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the braking torque is reduced by a fixed differential value in the reduction phase, then the control is simple, but the wheel may not re-accelerate rapidly enough under varying road conditions
Solution Approach 1:
The patent applies dynamics by making the differential braking torque adaptive rather than fixed. The control unit calculates the differential braking torque dynamically based on the measured wheel acceleration value, allowing the system to adapt to varying road conditions and wheel states, thereby achieving rapid wheel re-acceleration without excessive complexity
Solution Approach 2:
The patent implements feedback by using the measured wheel acceleration value from the build-up phase to determine the differential braking torque in the reduction phase. This closed-loop feedback mechanism ensures that the braking torque reduction is optimized based on actual wheel performance, enabling rapid re-establishment of braking action while maintaining controlled complexity
2Reliability
If the braking torque is reduced sharply to prevent wheel locking, then wheel locking is prevented, but the braking action is lost for too long
Solution Approach 1:
The patent applies partial action by reducing the braking torque to a specific target value rather than completely releasing it. The differential braking torque is calculated to achieve a target wheel acceleration that balances wheel locking prevention with maintaining braking action, avoiding excessive torque reduction that would cause prolonged braking loss
Solution Approach 2:
The system dynamically adjusts the differential braking torque based on measured wheel acceleration, enabling the braking torque to be reduced just enough to prevent wheel locking while minimizing the interruption of braking action. This dynamic adjustment optimizes the balance between reliability and time loss
3Speed
If the braking torque is increased rapidly in the build-up phase, then braking response is fast, but the wheel may lock before the optimal adhesion point is reached
Solution Approach 1:
The patent uses feedback by measuring the wheel acceleration value during the build-up phase and using this information to determine the appropriate differential braking torque in the reduction phase. This feedback mechanism allows the system to respond rapidly while maintaining precise control to prevent wheel locking
Solution Approach 2:
The patent implements periodic action through cyclic build-up and reduction phases. The braking torque is increased in build-up phases and reduced in reduction phases in a repeating cycle, allowing the system to rapidly respond while continuously monitoring and adjusting to prevent wheel locking at the optimal adhesion point
Data Source
AI summary
A method for operating an antilock brake system of a vehicle, in which a braking torque at at least one wheel of the vehicle is cyclically controlled in at least build-up phases and reduction phases, in order to prevent locking of the wheel. In a build-up phase, the braking torque is increased until a maximum adhesion at the wheel is exceeded, and in a subsequent reduction phase, the braking torque is reduced by a differential braking torque, which is ascertained, using a wheel acceleration value of the wheel measured after the build-up phase and a target acceleration value for the wheel.