Brake System Mode Downgrade Using Pre-Activation Performance Curves
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Solution Overview
Problem
Existing brake systems often switch to a hydraulic fallback mode unnecessarily, wasting potential braking performance and causing unpleasant sensations for the driver, as the downgrade process is only possible after the brake is activated.
Innovation Solution
A method for operating a brake system assembly that includes an evaluation device and actuators, allowing the system to downgrade from a by-wire mode to a hydraulic or mechanical mode based on pre-activation evaluation of performance curves, thereby selecting the mode with the greatest performance in each situation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the system switches to hydraulic fallback mode based on hard limit criteria, then system reliability is ensured, but brake power is unnecessarily reduced and driver comfort deteriorates
Solution Approach 1:
The system performs preliminary evaluation of the performance curve before brake activation to predict whether by-wire mode can maintain required performance. This advance assessment prevents unnecessary switching to hydraulic fallback mode, preserving brake power while ensuring reliability when needed.
Solution Approach 2:
The downgrade criterion is made dynamic by continuously evaluating the performance curve and comparing actual performance with required performance during braking. This dynamic assessment allows the system to maintain by-wire mode longer and switch to hydraulic mode only when actually needed, rather than using static hard limits.
2Reliability
If the system switches to hydraulic fallback mode during braking, then safety is ensured, but driver comfort deteriorates due to unpleasant sensations
Solution Approach 1:
The performance curve is evaluated before brake activation to predict potential mode switching. By knowing in advance whether by-wire mode can maintain performance, the system avoids unexpected switching during braking that causes driver discomfort, while still ensuring safety through continuous monitoring.
Solution Approach 2:
The system continuously monitors actual braking performance against the required performance during braking and provides feedback to the control unit. This real-time feedback allows the system to maintain by-wire mode as long as performance requirements are met, improving driver comfort while ensuring safety.
3Reliability
If the system uses hard limit criteria for mode switching, then system limits are protected, but potential brake power is wasted
Solution Approach 1:
The system replaces static hard limit criteria with dynamic performance-based criteria. By continuously evaluating the performance curve and comparing actual performance with required performance, the system adapts the downgrade decision to current operating conditions, maintaining by-wire mode longer and reducing unnecessary brake power loss while still protecting system limits.
Solution Approach 2:
The system changes the criterion for mode switching from fixed parameter thresholds (hard limits) to a dynamic performance ratio (actual performance/required performance). This parameter change allows the system to maintain by-wire mode across a wider range of operating conditions, preserving brake power while still ensuring system limits are not exceeded.
4Measurement precision
If the system evaluates downgrade criteria only after brake activation, then accurate performance assessment is possible, but downgrade timing is delayed
Solution Approach 1:
The system performs preliminary evaluation of the performance curve before brake activation to predict whether by-wire mode can maintain required performance. This advance assessment enables timely downgrade decisions when needed, while continuous monitoring during braking ensures accurate performance assessment is maintained throughout the braking event.
Data Source
AI summary
A method for operating a brake system assembly includes evaluating input data and downgrading from a first mode to a second mode according to the result of the evaluation. The input data is a performance curve of the first mode and determining the performance curve includes using a torque-speed curve, a first mode-dependent characteristic curve with at least one mathematical formula. Evaluating the input data includes comparing an ascertained performance capability of the first mode according to the calculated performance characteristic with the performance capability of the second mode.