Rebreather Oxygen Sensor Automatic Testing and Data Logging
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Solution Overview
Problem
Existing rebreather systems face issues with oxygen sensor errors, such as nonlinearity and current limitation, which are not reliably detected, and lack efficient data recording and transfer capabilities, especially during diving operations.
Innovation Solution
An automatic testing system is implemented, triggered during diving, which uses ambient pressure to test oxygen sensors at higher partial pressures, and includes a micro-controller for signal processing and data storage, allowing for continuous data recording and transfer via a memory card.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pO2 sensors are used to monitor oxygen partial pressure in rebreathers, then the safety and control of breathing gas is improved, but the sensors are prone to errors such as nonlinearity, current limitation, and calibration issues which can lead to erroneous readings
Solution Approach 1:
The patent changes the operating parameters of the pO2 sensor by exposing it to different oxygen partial pressures (0.2 bar, 0.6 bar, 1.0 bar) during automated testing. This allows detection of nonlinearity and current limitation errors by comparing sensor responses across multiple pressure levels, thereby improving measurement precision while maintaining reliability
Solution Approach 2:
The system implements automated feedback testing where the pO2 sensor is continuously monitored against known reference values during diving operations. When deviations are detected, the system provides feedback signals to alert the diver or automatically adjust the oxygen supply, ensuring reliable and precise pO2 control throughout the dive
2Ease of operation
If sensors are tested at the water surface with air or 100% O2 under normobaric conditions, then calibration is simplified, but the maximal reachable pO2 is limited to 1.0 bar which is insufficient for detecting errors during actual diving operations at higher pressures
Solution Approach 1:
The system performs preliminary automated testing and calibration of the pO2 sensor at multiple oxygen partial pressures (including 0.6 bar and 1.0 bar) before the diver descends to depth. This preliminary action ensures the sensor is properly calibrated for high-pressure conditions while maintaining ease of operation through automation, resolving the contradiction between calibration simplicity and testing reliability
Solution Approach 2:
The testing system dynamically adjusts the oxygen partial pressure applied to the sensor during calibration and testing phases. Rather than using fixed normobaric conditions, the system dynamically varies pressure levels to simulate actual diving conditions, ensuring reliable error detection while maintaining operational simplicity through automated control
3Reliability
If three oxygen sensors are used with a voting algorithm to detect sensor failures, then redundancy is improved, but the system cannot detect nonlinearity or current limitation errors that affect multiple sensors in the same way
Solution Approach 1:
The patent applies parameter changes by testing each sensor at multiple oxygen partial pressures (0.2 bar, 0.6 bar, 1.0 bar) rather than relying solely on voting at a single pressure level. This reveals nonlinearity and current limitation errors that would otherwise affect multiple sensors identically, thereby improving error detection capability while maintaining the benefits of sensor redundancy
4Loss of information
If detailed diving data is recorded for analysis, then the quality of diving analysis is improved, but special interface cables are required for data transfer which are often not available on the spot
Solution Approach 1:
The patent implements universal data retrieval by enabling multiple output formats and interfaces for the recorded diving data. The system can export data in common formats (CSV, TXT) that can be read by any standard computer without specialized cables, while maintaining complete data recording capabilities. This multi-functionality resolves the contradiction between data completeness and retrieval convenience
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
This system reliably detects oxygen sensor errors and ensures accurate oxygen monitoring, enabling safe operation and efficient data analysis, even with a single oxygen sensor, and allows data transfer using a standard personal computer.
Implementation Method 1
Fully-closed circuit rebreathers need pO2 sensors for manual or electronically controlled adjustment of pO2 in the loop. Normally electro-chemical sensors are employed as pO2 sensors
Implementation Method 2
the one oxygen sensor is tested by flushing with a gas with known oxygen concentration
Data Source
AI summary
The invention relates to a method for operating a rebreather, wherein oxygen is metered to the breathing gas as a function of a signal of at least one oxygen sensor (11). The oxygen sensor (11) is checked automatically by rinsing it with a gas having a known oxygen concentration. The safety of the system is improved in that the check is triggered automatically.