Brake Pedal Contactor Diagnosis via Speed-Adaptive Timeout
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Solution Overview
Problem
Existing methods for diagnosing brake pedal switches in motor vehicles are inadequate as they fail to accurately differentiate between transient states and real failures, leading to false failure detection or non-detection, and do not account for varying vehicle conditions.
Innovation Solution
The method involves an electronic control unit (ECU) that tests signals from contactors, initiating a delay based on vehicle speed when an inconsistent state is detected, with longer delays at low speeds to avoid false failures and shorter delays at high speeds to quickly detect faults, allowing for accurate diagnosis of contactor status.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed timeout delay is used to diagnose contactor failures, then transient states can be accounted for, but false failure detection occurs at low speeds and non-detection occurs at high speeds
Solution Approach 1:
The patent applies dynamics by making the timeout delay variable rather than fixed. The delay duration is dynamically adjusted based on vehicle speed: longer delays at low speeds to accommodate transient driver behavior, and shorter delays at high speeds to quickly detect actual failures. This dynamic adaptation resolves the contradiction between reliability and adaptability across different operating conditions.
Solution Approach 2:
The patent changes the parameter of timeout delay duration based on the parameter of vehicle speed. By establishing a relationship where the diagnostic timeout is a function of speed, the system adapts its diagnostic criteria to match the physical reality of driver behavior at different speeds, thereby improving both accuracy and adaptability.
2Productivity
If the diagnostic threshold is set to detect failures quickly, then real failures are identified promptly, but false failures are detected during normal transient operations
Solution Approach 1:
The system dynamically adjusts the diagnostic threshold (timeout delay) based on operating conditions. During transient operations at low speeds, the threshold is relaxed (longer delay), allowing temporary inconsistent states without triggering false alarms. During normal operations or at high speeds, the threshold becomes stricter (shorter delay), enabling quick detection of actual failures. This dynamic thresholding resolves the contradiction between detection speed and false alarm rate.
3Reliability
If a speed-dependent delay is implemented for contactor diagnosis, then false failures are reduced at low speeds, but the diagnostic system becomes more complex
Solution Approach 1:
The patent makes the existing diagnostic system multi-functional by enabling it to operate effectively across different speed regimes. The same diagnostic logic handles both transient low-speed operations and high-speed failure detection by simply adjusting the timeout parameter based on speed input. This universal approach reduces false failures without requiring entirely separate diagnostic systems for different conditions, thereby limiting the increase in complexity.
Data Source
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AI summary
The invention relates to a method for diagnosing brake pedal contactors of an automobile that comprises an electronic control unit (ECU), the contactors being connected to the ECU and supplying thereto information on the pedal position, characterised in that it comprises a step during which the ECU tests the signals from the contactors; if the signals indicate that the operation state is a so-called incoherent one, in which the brake pedal is considered by the ECU to be both depressed and released, the ECU initiates a time out (T1, T4), the duration of the time out depending on the vehicle speed.