Optoelectronic Sensor Interference Compensation via Control Windows
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Solution Overview
Problem
Optoelectronic sensor arrangements face interference from stray light signals, particularly when adjacent sensors with similar cycle times are operated, leading to false positive or false negative object detection signals, which can impair the availability and safety of monitored machines.
Innovation Solution
The sensor arrangement includes a control unit that activates the light receiver during additional control time windows before and after the detection time window to evaluate interference signals, determining an interference signal measure based on the size ratio of control variables derived from these signals, allowing for adjustment of transmission and reception time intervals to avoid interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the light receiver is activated continuously to detect all light signals, then detection completeness is improved, but interference signal reception increases
Solution Approach 1:
The control unit determines the interference signal measure in advance (before the detection time window) based on control signal profiles detected in control time windows. This preliminary assessment allows the system to prepare appropriate interference compensation before actual object detection begins, resolving the contradiction by proactively addressing interference rather than reactively filtering it during continuous reception.
Solution Approach 2:
The system dynamically adjusts the evaluation of received light signals by changing the interference signal measure parameter. Based on the determined interference signal measure, the control unit modifies how detection signals are evaluated during the detection time window, allowing the receiver to remain active for complete detection while adaptively compensating for interference through parameter adjustment rather than physical filtering.
2Ease of operation
If adjacent sensor arrays operate with the same cycle time to synchronize detection, then system coordination is improved, but mutual interference increases
Solution Approach 1:
The control unit uses feedback from detected control signal profiles to determine the interference signal measure. By continuously monitoring signals from adjacent sensor arrays and using this information to adjust the evaluation of detection signals, the system maintains synchronized operation while compensating for mutual interference through adaptive feedback control rather than desynchronization.
Solution Approach 2:
The system changes the evaluation parameter (interference signal measure) based on the actual interference conditions detected from adjacent arrays. This allows synchronized operation to be maintained for system coordination while the dynamic parameter adjustment compensates for the resulting mutual interference, resolving the contradiction between coordination and interference avoidance.
3Measurement precision
If the detection time window is extended to capture more signals, then detection accuracy is improved, but interference exposure duration increases
Solution Approach 1:
The system converts the harmful effect of extended interference exposure into a beneficial measurement tool. By using the control signal profiles detected during the extended detection time window to determine the interference signal measure, the system transforms the additional interference data into useful information for compensating and correcting detection signals, thereby improving accuracy despite longer exposure.
Solution Approach 2:
The system extends the detection time window while compensating for the increased interference exposure by dynamically adjusting the interference signal measure parameter. This parameter change allows the system to utilize the extended window for improved signal capture while simultaneously correcting for the additional interference through adaptive evaluation based on the determined interference measure.
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 approach enhances the sensor's resistance to interference signals, reducing false detections and maintaining system reliability and safety by dynamically adjusting the timing of light signal transmission and reception.
Implementation Method 1
With a photoelectric sensor, the emitted light signals are reflected by any object present in the monitored area
Implementation Method 2
a light receiver for detecting received light signals and converting the received light signals into electrical received signals
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
The invention relates to an optoelectronic sensor arrangement comprising a light transmitter, a light receiver, and a control unit for generating an object detection signal when an object present in the monitored area is detected. The control unit is configured to cyclically activate the light transmitter at predetermined time intervals for a predetermined transmission duration to emit a respective light signal, and to activate the light receiver at least for the duration of a detection window encompassing the transmission duration, with the object detection signal being generated based on the received light signals detected during the detection window.According to the invention, the control unit is further configured to activate the light receiver for the duration of a first control time window beginning before the detection time window to detect a first control signal curve and for the duration of a second control time window ending after the detection time window and not overlapping with the first control time window to detect a second control signal curve, to determine a disturbance signal measure based on a magnitude ratio between a first control quantity derived from the first control signal curve and a second control quantity derived from the second control signal curve, and to adjust the aforementioned time intervals at least on the basis of the disturbance signal measure.