Marine Heat Source Sensor with Asymmetric Light Shields
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Solution Overview
Problem
Existing heat detection systems for marine vessels are prone to false triggering due to sunlight reflection from the water and intense infrared signals from heated outboard motor cowls, making it difficult to accurately sense the presence of heat-emitting objects like mammals in marine environments.
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, including areas affected by direct sunlight and outboard motor cowls, using Fresnel lenses and asymmetrical light shield designs to enhance detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the field of view of the heat sensor is expanded to detect heat sources in all directions, then the detection coverage is improved, but false triggering increases due to sunlight reflection and outboard motor cowls
Solution Approach 1:
The detection system is divided into multiple independent sensor units, each with its own housing structure and light shield. Each sensor unit independently monitors a specific zone, allowing the system to achieve broad coverage while maintaining reliability through localized detection zones that avoid false triggering sources.
Solution Approach 2:
Each sensor unit is configured with asymmetric light shields that create non-uniform field of view patterns. The light shields are specifically designed to block sunlight and outboard motor cowls from certain directions while maintaining detection capability in other directions, creating locally optimized detection zones that avoid false triggers.
2Reliability
If light shields are added to block sunlight and outboard motor cowls, then false triggering is reduced, but the field of view is restricted
Solution Approach 1:
The solution moves from a two-dimensional field of view consideration to a three-dimensional spatial arrangement. Multiple sensor units are positioned at different locations and angles on the transom, creating overlapping detection zones that collectively cover the entire rear area. This multi-dimensional arrangement allows light shields to block specific directions for each sensor while maintaining overall comprehensive coverage.
Solution Approach 2:
Multiple sensor units with restricted individual fields of view are combined to create a comprehensive detection system. The asymmetric light shields of each sensor unit are positioned to block specific interference sources (sunlight, outboard motor cowls) while maintaining detection in other directions. When multiple such sensors are combined, their individual restricted fields of view merge to provide complete coverage without false triggering.
3Measurement precision
If multiple sensor units are deployed to cover the rear area, then detection accuracy is improved, but system complexity increases
Solution Approach 1:
The system uses identical or substantially similar sensor unit designs positioned at different locations. Each sensor unit is a copy of the same basic structure with the same housing, light shield configuration, and detection elements. This modular copying approach improves detection accuracy through multiple sensors while minimizing system complexity by using standardized, interchangeable components that simplify installation and maintenance.
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 effectively reduces false alarms by blocking direct sunlight and infrared radiation from outboard motor cowls, allowing for accurate detection of heat-emitting objects behind a marine vessel, while minimizing interference from ambient infrared sources.
Implementation Method 1
a first light sensitive element mounted in the first housing structure and configured to have a first field of view
Implementation Method 2
using Fresnel lenses and asymmetrical light shield designs to enhance detection accuracy
Implementation Method 3
The system effectively reduces false alarms by blocking direct sunlight and infrared radiation from outboard motor cowls
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.