WPAN Sensor Pairing for Refrigerated Containers
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Solution Overview
Problem
Incorporating wireless door sensors into refrigerated container systems poses unique challenges, including excessive sensor signal processing from chattering doors and inadvertent pairing with coordinators, which can lead to battery drain and inefficient operation.
Innovation Solution
Implementing a wireless personal area network (WPAN) with a coordinator node that manages sensor pairing through specific actuation sequences, actively purges erroneous coordinator entries, and employs a timer-based processing routine to stabilize door sensor signals, preventing excessive processing and ensuring accurate pairing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wireless door sensors are incorporated into refrigerated container systems, then monitoring capability is improved, but battery drain and signal processing overhead increase
Solution Approach 1:
The patent implements a timer-based processing routine that operates periodically rather than continuously. The routine is triggered at predetermined time intervals to read door sensor signals, replacing continuous monitoring with periodic sampling. This reduces the frequency of signal processing operations and extends battery life while maintaining adequate monitoring capability.
Solution Approach 2:
The system employs automatic purging of coordinator entries from the pairing table without requiring manual intervention. The wireless sensor node autonomously identifies and removes erroneous coordinator entries based on connection failure criteria, reducing operational overhead and maintaining network integrity without additional human resource consumption.
2Measurement precision
If continuous door sensor signal processing is implemented, then door state detection accuracy is improved, but excessive processing from chattering doors increases energy consumption
Solution Approach 1:
The timer-based processing routine reads door sensor signals at predetermined time intervals rather than continuously responding to every signal change. This periodic sampling approach filters out high-frequency chattering signals while still capturing meaningful door state changes, reducing energy consumption without significantly compromising detection accuracy.
Solution Approach 2:
The system performs preliminary validation of door sensor signals by checking multiple consecutive readings before triggering processing actions. This preliminary filtering prevents excessive processing of spurious chattering signals while maintaining responsiveness to genuine door state changes.
3Ease of operation
If automatic pairing with coordinators is enabled, then network setup ease is improved, but inadvertent pairing with wrong coordinators causes operational errors
Solution Approach 1:
The wireless sensor node autonomously manages its pairing table by automatically identifying and purging erroneous coordinator entries. The system monitors connection status and removes coordinators that fail to respond or exhibit incorrect behavior, maintaining pairing table integrity without manual intervention and preventing operational errors from wrong coordinator pairings.
Solution Approach 2:
The system implements feedback mechanisms where the sensor node monitors coordinator responses and connection status. Based on this feedback, the node adjusts its pairing table, removing coordinators that do not meet expected performance criteria. This feedback-driven approach ensures reliable pairing while maintaining ease of automatic network setup.
Data Source
AI summary
A refrigerated container system is described that includes a wireless personal area network (WPAN) including a plurality of wireless sensor nodes and a coordinator node through which the sensors provide sensor data to a controller for the refrigerated container system. The wireless sensors and the coordinator incorporate a variety of features that ensure efficient utilization of battery life by preventing unintended pairing of sensors with other WPANs and excessive sensor signal processing arising from door chatter. Finally, pairing is performed without pressing a button on the wireless door sensor. Instead, the sensor's magnetic reed switch is enlisted to detect swiping of a magnet by a user to enter a pairing mode.