Work Vehicle Speed Sensor Failure Detection Using State Feedback
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Solution Overview
Problem
Existing work vehicles lack effective methods to detect failures in speed sensors, which can lead to unsafe operating conditions when the sensor indicates a null speed but the vehicle is moving, often unnoticed by the operator.
Innovation Solution
A method to detect speed sensor failures by monitoring specific conditions such as zero vehicle speed, non-neutral transmission, brake release, and high engine speed, providing an error signal to the operator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If no speed sensor failure detection method is implemented, then the work vehicle operates without additional safety systems, but unsafe operating conditions go unnoticed when the sensor indicates null speed while the vehicle is moving
Solution Approach 1:
The control system continuously monitors multiple parameters (speed sensor output, transmission state, brake pedal position, engine speed) and compares them against expected operational relationships. When inconsistencies are detected (e.g., sensor indicates zero speed while engine speed and transmission state indicate motion), the system generates an error signal to alert the operator, creating a feedback loop that enhances safety without requiring additional hardware sensors
Solution Approach 2:
The existing vehicle systems (engine speed sensor, transmission state indicators, brake pedal position sensors) are repurposed to detect speed sensor failures. Rather than adding dedicated failure detection hardware, the system uses self-service by having existing components perform dual functions: their primary functions plus failure detection of the speed sensor, thereby avoiding increased device complexity
2Reliability
If a speed sensor failure detection method is implemented, then safety is enhanced by detecting malfunctions, but the vehicle cost increases
Solution Approach 1:
The control system is designed to perform multiple functions: normal vehicle operation control, speed monitoring, and failure detection of the speed sensor itself. By making the control system universal and multi-functional, the patent avoids the need for separate dedicated failure detection hardware, thereby enhancing safety while minimizing additional manufacturing costs
Solution Approach 2:
The system uses existing vehicle components (engine speed sensor, transmission state indicators, brake pedal position sensors) to detect speed sensor failures. This self-service approach allows the vehicle's own existing systems to perform the failure detection function, eliminating the need for additional expensive hardware and reducing manufacturing costs while improving safety
3Productivity
If the speed sensor indicates null speed while the vehicle is moving, then the operator may continue working, but this leads to unsafe operating conditions going unnoticed
Solution Approach 1:
The control system establishes feedback monitoring of the relationship between speed sensor output and other vehicle state parameters. When the sensor incorrectly indicates zero speed while the vehicle is actually moving (detected through engine speed, transmission state, and brake position), the system provides immediate feedback through an error signal to the operator, allowing work to continue safely with operator awareness rather than proceeding unnoticed
4Measurement precision
If multiple conditions are monitored to detect speed sensor failure, then detection reliability is improved, but the control system complexity increases
Solution Approach 1:
The control system monitors multiple parameters (speed sensor output, transmission state, brake pedal position, engine speed) and uses feedback logic to compare their relationships. This multi-parameter feedback approach improves detection accuracy by cross-validating information from multiple sources, while the feedback mechanism itself provides a structured method to manage the complexity through systematic comparison of expected vs. actual operational relationships
Data Source
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AI summary
A method for detecting a failure of a speed sensor means of a work vehicle is disclosed. The method comprises the step of: - if the following conditions are simultaneously met for a predetermined accumulated amount of time, determining that a failure of the speed sensor means occurred: a) the travel speed of the work vehicle indicated by the speed sensor means is zero; b) a FNR (Forward-Neutral-Reverse) switch (FNR) is not in a neutral position; 5c) a brake pedal is not pressed by an operator; d) a joystick is in the neutral position or a hydrostatic circuit of the boom has been decoupled from the hydrostatic transmission by the operator by means of a command means; e) a driving current provided to a forward solenoid of a pump or to a reverse solenoid of a pump is greater than a predetermined current threshold; f) a rotational speed of a motor arranged to power the work vehicle is higher than a predetermined rotational speed threshold.