Optical Sensor Signal Correction for Fermenter Bubble Interference
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Optical sensors in process analysis, such as those used in fermenters, face disturbances in measurement due to gas bubbles that interfere with the sensor's ability to accurately monitor parameters like dissolved oxygen or electrical conductivity, leading to abrupt changes in measurement signals and regulatory issues.
Innovation Solution
A method involving an optical measuring device with a light source, active sensor layer, and control unit that emits and detects light signals to determine primary and secondary measurement parameters, compares the secondary signal to a limit value, and filters the primary signal to correct for disturbances caused by gas bubbles, using techniques like moving average filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If gas bubbles are introduced into the fermenter for oxygen supply, then bacterial growth is controlled, but measurement signals change abruptly and regulation is disturbed
Solution Approach 1:
A secondary measurement parameter is introduced as an intermediary to detect the presence of gas bubbles. This secondary parameter serves as a mediator that identifies disturbance conditions without directly affecting the primary measurement, allowing the system to recognize when gas bubbles are present and trigger appropriate correction or filtering of the primary measurement signal.
Solution Approach 2:
The system uses feedback by comparing the secondary measurement signal with a limit value to determine when correction is needed. The feedback loop continuously monitors the secondary parameter and adjusts the processing of the primary measurement signal accordingly, smoothing the output when gas bubbles are detected and restoring normal measurement when conditions return to normal.
2Measurement precision
If gas bubbles settle on the optical sensor, then contact between sensor and liquid medium is prevented, but measurement accuracy is maintained through correction
Solution Approach 1:
The system performs preliminary detection using the secondary measurement parameter to identify the presence of gas bubbles before they completely disrupt the primary measurement. By detecting the disturbance early through the secondary parameter, the system can prepare for and apply correction measures to maintain measurement accuracy throughout the bubble event.
Solution Approach 2:
The system changes the state of the measurement signal by applying smoothing correction when gas bubbles are detected. The control unit modifies the primary measurement signal based on the secondary parameter comparison, transforming the raw disturbed signal into a corrected output that maintains accuracy despite the presence of gas bubbles on the sensor.
3Measurement precision
If the primary measurement signal is smoothed to correct gas bubble interference, then measurement accuracy is improved, but response time may be reduced
Solution Approach 1:
The system applies smoothing correction only partially - specifically when and only when gas bubbles are detected through the secondary measurement parameter. Rather than continuously smoothing all measurements (which would always reduce response time), the system applies the smoothing action selectively only when needed, maintaining fast response during normal conditions while improving accuracy during bubble interference.
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 method effectively detects and corrects for gas bubble interference, enhancing the accuracy of optical sensor measurements by smoothing the primary signal only when necessary, thereby minimizing disturbances in process regulation.
Implementation Method 1
Emitting a first light signal from the light source to the active sensor layer so that the active sensor layer is stimulated and a second light signal is emitted to the optical detector, Detecting the second light signal emitted by the active sensor layer by means of the optical detector
Data Source
AI summary
The present disclosure includes a method for correcting a primary measurement signal detected by an optical detector. The method includes: emitting a first light signal from a light source to an active sensor layer such that the active sensor layer is stimulated and emits a second light signal, which is detected by an optical detector; determining the primary measurement signal of a primary measurement parameter based on the second light signal and/or the first light signal; determining a secondary measurement signal of a secondary measurement parameter that is different from the primary measurement parameter based on the first light signal or the second light signal; comparing the determined secondary measurement signal with a first limit value; and correcting the primary measurement signal when the secondary measurement signal exceeds the first limit value, wherein correcting the primary measurement signal comprises smoothing the primary measurement signal by filtering.