Electro-Actuated Brake Fault Detection Using a Caliper Model
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Solution Overview
Problem
Existing methods for detecting malfunctions in electro-actuated brake systems of motor vehicles require complex operations and cannot adapt to varying operating conditions without acquiring signals from multiple brakes, limiting their effectiveness and efficiency.
Innovation Solution
A method that uses an electronic control unit connected to an electro-actuated brake caliper, which generates a target signal and compares it with feedback signals to detect errors, allowing for adaptive validation times based on error intensity, and does not require signals from two different brakes, employing a numerical model to simulate both linear and non-linear behaviors of the brake system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex operations are performed for malfunction detection, then detection accuracy may be improved, but detection time increases and system complexity increases
Solution Approach 1:
The patent pre-calculates and stores reference values for brake actuator commands and expected wheel speeds before malfunction detection is needed. During operation, the system simply compares actual measurements against these pre-computed references, avoiding complex real-time calculations and enabling rapid malfunction detection within tens of milliseconds
Solution Approach 2:
The system creates a virtual model by computing expected wheel speeds based on commanded brake actuator positions and vehicle dynamics models. This virtual copy is then compared against actual wheel speed measurements to detect malfunctions, simplifying the detection process while maintaining high accuracy
2Reliability
If signals from two different brakes are acquired for comparison, then malfunction detection capability is improved, but device complexity and signal acquisition requirements increase
Solution Approach 1:
The system uses the vehicle's existing wheel speed sensors and brake actuator command signals to perform self-diagnosis. By comparing commanded brake actions against actual wheel speed responses, the system detects malfunctions using data already available in the brake-by-wire system, eliminating the need for additional sensors or complex multi-brake comparison systems
Solution Approach 2:
The system continuously monitors the feedback relationship between brake actuator commands and actual wheel speed responses. By analyzing whether the actual response matches the expected response based on commanded actions, the system detects malfunctions using existing feedback loops already present in the brake control system
3Measurement precision
If validation time is extended for accurate error detection, then detection accuracy is improved, but response speed to malfunctions decreases
Solution Approach 1:
The system dynamically adjusts validation requirements based on error intensity. For small errors, multiple validation cycles are performed to ensure accuracy and avoid false positives. For large errors indicating serious malfunctions, the system reduces validation requirements and triggers immediate alerts, optimizing the balance between accuracy and response speed
Solution Approach 2:
The system changes validation parameters based on the magnitude of detected errors. When error signals exceed certain thresholds, the system adjusts the number of validation cycles required, allowing rapid response to severe malfunctions while maintaining rigorous validation for minor variations
Data Source
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AI summary
The invention relates to a method for detecting malfunctions of an electro-actuated brake apparatus (100; 200) of a motor vehicle. The apparatus includes: an electronic control unit (50; 50'); an electro-actuated brake caliper (10; 20) electrically actuated by the electronic control unit for generating a clamping force (Fc) on a disc (15) of the brake apparatus in response to a control signal (Sp) generated by the electronic control unit. The method comprising the steps of: providing, in the electronic control unit, a functional control block (51) and a first functional block (60; 60') consisting of a numerical model representative of the electro- actuated brake caliper; providing a target signal (BT) to the functional control block for generating said control signal to operate the electro-actuated brake caliper; providing said target signal to the first functional block for generating a first signal (S1; S1') representative of a theoretical quantity associated with the numerical model representative of the electro-actuated brake caliper; comparing said first signal with a feedback signal (Sf'; Spi') representative of a real operating quantity associated with the electro-actuated brake caliper for generating an error signal to be sent to a second functional block (70) of the electronic control unit; performing, by said second functional block, an error validation check to provide information (R) on the operating state of the electro-actuated brake caliper to the electronic control unit.