Marine Heat Source Detection with Asymmetric Light Shields
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Solution Overview
Problem
Existing heat detection systems for marine environments are prone to false triggering due to sunlight reflection from water and intense infrared signals from heated outboard motor cowls, making it difficult to accurately sense heat-emitting objects like mammals.
Innovation Solution
A heat source sensor system comprising multiple housing structures with light sensitive elements and light shields, configured to limit fields of view and avoid false detection regions, using Fresnel lenses and asymmetric placement to detect heat sources effectively behind a marine vessel while minimizing false alarms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If infrared detectors are used to detect heat sources in marine environments, then heat-emitting objects can be detected, but false triggering occurs due to sunlight reflection from water and intense infrared signals from heated outboard motor cowls
Solution Approach 1:
The detection system is divided into multiple independent sensor units, each with its own housing structure, light sensitive element, and light shield. Each sensor unit independently monitors a specific field of view, and the system processes signals from multiple sensors to distinguish true heat sources from false triggers caused by sunlight reflection or motor heat.
Solution Approach 2:
Each sensor unit is configured with asymmetric light shields that selectively block infrared radiation from specific directions (such as the outboard motor cowl area) while allowing detection of heat sources in other directions. The light shields create localized detection zones with different sensitivity characteristics to reject specific interference sources.
2Area of stationary object
If the field of view is expanded to cover more detection area, then more heat sources can be detected, but false detection from sunlight reflection and motor heat increases
Solution Approach 1:
The overall detection area is divided into multiple smaller fields of view, each monitored by a separate sensor unit with asymmetric light shielding. This segmentation allows the system to achieve broad coverage while maintaining selective rejection of harmful infrared sources in specific directions through the asymmetric light shield configuration of each individual sensor.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system reduces false triggering by blocking direct sunlight and infrared radiation from outboard motor cowls, allowing accurate detection of heat-emitting objects with a combination of signals from multiple sensors, enhancing the reliability of heat source detection in marine environments.
Implementation Method 1
a light sensitive element mounted in the housing structure and having a field of view
Implementation Method 2
using Fresnel lenses and asymmetric placement to detect heat sources effectively
Data Source
AI summary
Two sensor units are mounted on opposite sides of a transom of a boat and directed to a common location behind the boat. The field of view of the two sensors overlaps behind the marine propulsion unit of the boat to detect the presence of a heat emitting object, such as a mammal. Housing structures contain infrared sensing elements, lenses, and light shields. Signals from four infrared sensing elements are received by a controller which reacts, with an alarm signal, when at least two of the four sensors detect a heat emitting object within their individual fields of view. False triggering can be reduced by not providing an alarm signal if only the two most inboard sensors detect the heat emitting object.