Watercraft Engine Speed Filtering for Accurate Max Speed Control
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Solution Overview
Problem
Existing maximum speed limiting control systems for watercraft are inaccurate due to the precision issues with watercraft speed sensors, such as pitot tubes or paddlewheel type sensors, which can lead to unnecessary speed limiting when the watercraft is not on water.
Innovation Solution
A watercraft system that uses an engine rotational speed sensor, a filter processing section, and a control section to determine if the watercraft is moving and apply a maximum speed limiting control only when the filtered engine rotational speed exceeds a threshold, ensuring the control is executed accurately and avoiding false triggers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If watercraft speed sensors (pitot tube or paddlewheel) are used to detect watercraft speed for maximum speed limiting control, then the control can be executed based on actual watercraft speed, but the detection accuracy is affected by water flow angle and sensor precision
Solution Approach 1:
The patent introduces an intermediary calculation method that combines engine rotational speed (easily and accurately measurable) with watercraft speed sensor data through filtered processing. This intermediary approach uses the relationship between engine speed and watercraft speed to compensate for sensor inaccuracies, particularly when water flow angle affects pitot tube or paddlewheel sensor readings.
Solution Approach 2:
The patent partially replaces direct mechanical water flow-based speed detection with an alternative measurement approach using engine rotational speed sensing. By substituting the direct watercraft speed measurement with engine speed measurement combined with filtering algorithms, the system reduces dependence on water flow angle and sensor placement precision.
2Measurement precision
If engine rotational speed is used to determine whether to execute maximum speed limiting control, then the detection is more accurate and easier, but false triggers occur when the watercraft is not on water (e.g., on ground)
Solution Approach 1:
The patent applies preliminary filtering processing to engine rotational speed data before using it for control decisions. The filter processing section pre-processes the engine speed signal to distinguish between legitimate speed increases (when watercraft is on water) and false conditions (when on ground), enabling more reliable determination of whether to execute maximum speed limiting control.
Solution Approach 2:
The system uses feedback from both engine rotational speed sensors and watercraft speed sensors in combination. The control section continuously monitors both signals and uses the filtered engine speed as a reference to validate watercraft speed measurements, creating a feedback mechanism that reduces false triggers while maintaining accurate speed limiting control.
Data Source
AI summary
In a watercraft, an engine rotational speed sensor detects a rotational speed of an engine. A determining section determines if a prescribed execution condition indicating that a hull body is moving is satisfied. A filter processing section applies a filter process to the engine rotational speed detected by the engine speed sensor to acquire a filtered engine rotational speed. A control section executes a maximum speed limiting control to limit a maximum speed of the watercraft when the prescribed execution condition is satisfied and the filtered engine rotational speed is larger than a prescribed rotational speed threshold value.