Wheel Speed Sensor Fault Detection in One-Channel ABS
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Solution Overview
Problem
In one-channel ABS systems with a single wheel speed sensor, the electronic control unit (ECU) cannot differentiate between a vehicle being stationary or the sensor being faulty, leading to potential non-operation of the ABS during wheel slip, as the ECU cannot accurately determine the sensor's status after initial take-off.
Innovation Solution
A monitoring device and method that utilize a control unit and indicator in a two-wheeled motor vehicle to differentiate between the vehicle's stationary state and sensor faults by setting distinct minimum speeds for initial take-off and traveling, using a warning light to notify the driver of potential sensor issues, ensuring the ABS operates correctly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a one-channel ABS with a single wheel speed sensor is used, then the device complexity is reduced and cost is lowered, but the reliability of fault detection deteriorates as the ECU cannot differentiate between vehicle stationary state and sensor failure
Solution Approach 1:
The system performs preliminary monitoring during initial take-off to establish a baseline wheel speed signal state before normal operation begins. This preliminary action allows the ECU to distinguish between a stationary vehicle (normal state) and a failed sensor (abnormal state) in subsequent operations, resolving the reliability issue without adding sensors.
Solution Approach 2:
The system changes the monitoring parameter threshold dynamically based on vehicle operation state. During initial take-off, the system monitors whether wheel speed exceeds a predetermined threshold value. This parameter change approach enables the ECU to differentiate between stationary and moving states, improving fault detection capability while maintaining single-sensor configuration.
2Measurement precision
If the ECU monitors wheel speed continuously after initial take-off, then the detection precision of sensor faults is improved, but the loss of time for false warnings increases when the vehicle is temporarily stationary during normal operation
Solution Approach 1:
The monitoring threshold is made dynamic rather than static. The system adjusts the predetermined threshold value based on the vehicle's operation phase: during initial take-off, a higher threshold is used to account for normal acceleration variations, while after take-off, the threshold remains to detect actual faults. This dynamic adjustment reduces false warnings during temporary stops while maintaining fault detection precision.
3Reliability
If a predetermined minimum speed threshold is set for fault detection, then the reliability of fault identification is improved, but the ease of operation deteriorates as the driver receives unnecessary warnings during normal stopping
Solution Approach 1:
The system performs a preliminary monitoring phase during initial take-off to establish whether the wheel speed sensor is functioning normally. Only after this preliminary confirmation does the system activate continuous monitoring with warning capabilities. This preliminary action ensures that the warning system is only active when the sensor is confirmed operational, preventing false warnings during normal stops and improving driver convenience while maintaining reliability.
Data Source
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AI summary
It is an object of the present invention to provide a monitoring device that can, even after having been able to confirm that wheel speed is normal at the time of initial take-off, monitor the possibility that a wheel speed sensor is faulty and warn or notify a driver of this. In a wheel speed sensor monitoring device used in a two-wheeled motor vehicle, the two-wheeled motor vehicle is equipped with a wheel speed sensor 2 that detects a wheel speed of one wheel, an ECU 10 that finds a vehicle body speed from the wheel speed and uses the wheel speed to perform ABS control of the wheel, and a warning light 8 that indicates the state of the vehicle body, and in a case where the vehicle body speed or the wheel speed is equal to or less than a predetermined minimum speed, the ECU 10 gives a notification of the possibility that the wheel speed sensor is faulty by causing the warning light 10 to light up or flash.