Fiber Optic Position Sensor Immune to EMI
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Solution Overview
Problem
Existing position sensors in industrial and harsh environments face challenges with electrical interference, noise, and safety hazards due to their reliance on electrical connections, which can lead to inaccurate readings and damage from lightning strikes or sparking.
Innovation Solution
A high-resolution fiber optic position sensor system that uses optical signals only, eliminating electrical components and utilizing a rotating disk with a non-repeating binary pattern to transmit position information through a single fiber optic line, processed by a microprocessor for accurate angular position measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical connections are used in position sensors, then power and signal transmission are enabled, but electromagnetic interference and lightning damage occur
Solution Approach 1:
The patent replaces electrical connections with optical fiber connections. The sensor head is electrically passive and communicates position information through optical signals transmitted via fiber optic cables to the controller, eliminating all electrical components from the sensor head and thus providing complete immunity to electromagnetic interference and lightning strikes.
2Measurement precision
If optical amplitude is used for position sensing, then position information can be transmitted, but signal stability deteriorates due to amplitude variations exceeding 10%
Solution Approach 1:
The patent changes the parameter used for position encoding from optical amplitude to optical spectrum. Instead of varying signal strength, the system embeds position information in the spectral distribution of light, which remains stable even when amplitude varies. The controller analyzes spectral characteristics rather than amplitude levels to determine position.
3Ease of operation
If electrical wires connect sensor to control unit, then power and data transmission are achieved, but ground loops and sparking hazards are created
Solution Approach 1:
The patent replaces electrical wiring with optical fiber cabling. The sensor head requires no electrical power or grounding, and position data is transmitted through optical signals in fiber optic cables. This eliminates ground loops, sparking hazards, and all electrical connection issues while enabling safe deployment in explosive and electrically noisy environments.
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 provides accurate and reliable position sensing immune to electromagnetic interference and lightning, with high resolution and precision, suitable for applications in EMI/RFI intense environments and hazardous settings without the need for electrical power or connections.
Implementation Method 1
an optical power source contained in said controller that sends a light pulse to said sensor head through said at least one fiber optic line
Implementation Method 2
The sensor modulates the optical signal based on the exact position of the sensor disk. This modulated optical signal is analyzed in the controller and translated into the position signal.
Implementation Method 3
The controller unit analyzes this modulated optical spectrum and determines the angular position of the shaft in the sensor head
Data Source
AI summary
A high resolution fiber optic position sensor system including a remote sensor head connected by a pair of optical fibers to an electronic controller unit. The sensor is an electronically passive device that utilizes optical signals only that senses the angular absolute position over the full 360° rotation with a sensing resolution of 13 bit (8196). The sensor modulates the optical signal based on the exact position of the sensor disk. This modulated optical signal is analyzed in the controller and translated into the position signal. Because the sensor head is electrically passive it can be deployed in an EMI/RFI intense environment. Further, it is immune to lightening strikes and can also be located many hundred meters away from the control unit without creating undesirable ground loops.