SAW Proximity Sensor for Aviation Weight Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current proximity sensors in the aviation industry are heavy, complex, and difficult to maintain, with existing alternatives like voltage sensing capacitive sensors, magnetic, and optical switches being prone to failure and interference, and requiring extensive wiring that increases weight and costs.
Innovation Solution
A surface acoustic wave (SAW) proximity sensor that uses a SAW device with a sensing section to determine object position without batteries, utilizing reflective structures and resonant circuits to differentiate between near and far field positions, eliminating the need for heavy isolation hardware and wiring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heavy armored proximity sensors are used to detect metal objects, then detection capability is improved, but weight increases significantly
Solution Approach 1:
The patent replaces traditional mechanical/electromagnetic field-based proximity sensors with surface acoustic wave (SAW) technology. SAW sensors use acoustic waves propagating along a piezoelectric substrate surface to detect proximity, eliminating the need for heavy electromagnetic shielding and complex mechanical components while maintaining detection capability in harsh aviation environments.
Solution Approach 2:
The invention changes the fundamental operating parameter from electromagnetic field detection to acoustic wave propagation. By using SAW devices that generate and detect acoustic waves along a substrate surface, the system achieves proximity detection without requiring heavy armor plating, reducing weight while preserving reliability.
2Weight of moving object
If voltage sensing capacitive type sensors are used, then weight is reduced, but heavy isolation hardware is still required due to EMI
Solution Approach 1:
The patent substitutes electromagnetic voltage sensing with acoustic wave-based sensing. SAW sensors detect proximity through changes in acoustic wave propagation characteristics along the substrate surface, which are inherently immune to electromagnetic interference, eliminating the need for complex isolation hardware while keeping the device lightweight.
3Weight of moving object
If magnetic or optical interrupt switches are used, then weight is reduced, but reliability decreases in harsh conditions
Solution Approach 1:
The invention transitions from magnetic field or optical detection to acoustic wave propagation along a solid substrate. SAW sensors use piezoelectric materials that generate and detect acoustic waves, which are resistant to contamination, ferrous filings, and foreign objects that plague magnetic and optical switches, thereby improving reliability in harsh aviation conditions while maintaining low weight.
4Device complexity
If wireless sensor devices like Zigbee are used, then wiring complexity is reduced, but power requirements increase
Solution Approach 1:
The patent implements a passive SAW sensor system that requires no external power source. The sensor is interrogated by RF signals from an external reader, which excite acoustic waves on the SAW device. The sensor modulates the reflected RF signal with proximity information, enabling wireless communication without batteries or power consumption, thus avoiding the power requirements of active wireless systems like Zigbee.
5Use of energy by moving object
If RFID with inductive coupling is used, then passive operation is achieved, but performance falls below aviation standards
Solution Approach 1:
The patent replaces inductive coupling-based RFID with surface acoustic wave technology. SAW sensors use acoustic wave propagation along a piezoelectric substrate surface, which provides more stable and reliable performance in aviation environments. The acoustic waves are less susceptible to interference and provide more consistent operation, meeting stringent aviation standards while maintaining passive operation.
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 SAW proximity sensor provides a robust, lightweight solution that reduces weight and complexity, enhances reliability, and minimizes maintenance costs by using wireless communication and passive power, effectively addressing the limitations of prior sensors.
Implementation Method 1
SAW devices generate guided acoustic waves along a surface of the device
Implementation Method 2
SAW devices are generally fabricated on single crystal anisotropic substrates that are also piezoelectric
Implementation Method 3
The substrate may have other IDTs or other structures to generate a reflection wave that the input/output converts to an electrical signal
Data Source
AI summary
A proximity sensor for determining a position of an object. The proximity sensor includes a SAW device having a load end and an input end for receiving an input pulse. A sensing section connects to the load end of the SAW device. When the object is in a first position, the sensing section provides a first response indicative of the first position and, when the object is in a second position, the sensing section provides a second response indicative of the second position such that the position of the object can be determined based upon the response to the input pulse.