# US 2013/0252552 A1 · Door Ajar Detection and Recovery for a Wireless Door Sensor

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- Number: US 2013/0252552 A1
- Document ID: US20130252552A1
- Status: Published application
- Kind: A1
- Application number: 13/709,385
- Filed: 2012-12-10
- Published: 2013-09-26
- Earliest claimed: 2012-03-21
- Assignees: Invensys Systems, Inc.
- Inventors: Kimble Allyn Vitkus; Stephen Michael Pasek; Mark Alan Johnson; Russell Lee Sanders; Mark Daniel Leasure
- Web page: https://patentgrep.com/patent/US20130252552A1

## CPC

- G08C 15/04: the signals being modulated on carrier frequencies
- H04Q 9/00: Arrangements in telecontrol or telemetry systems for selectively calling a substation from a main station, in which substation desired apparatus is selected for applying a control signal thereto or for obtaining measured values therefrom
- H04W 4/21: for social networking applications
- H04W 4/80: Services using short range communication, e.g. near-field communication [NFC], radio-frequency identification [RFID] or low energy communication
- H04Q 2209/43: using wireless personal area networks [WPAN], e.g. 802.15, 802.15.1, 802.15.4, Bluetooth® or Zigbee®
- H04Q 2209/883: where the sensing device enters an active or inactive mode
- H04W 52/0219: {where the power saving management affects multiple terminals}
- Y02D 30/70: in wireless communication networks
- G08C: TRANSMISSION SYSTEMS FOR MEASURED VALUES, CONTROL OR SIMILAR SIGNALS (fluid pressure transmitting systems F15B; mechanical means for transferring the output of a sensing member into a different variable G01D5/00; mechanical control systems G05G)
- H04Q: SELECTING (switches, relays, selectors H01H; wireless communication networks H04W)
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)
- Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE

## Abstract

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.

## Claims

### Claim 1

A method of managing a wireless door sensor to avoid excessive sensor signal processing arising from a chattering door sensor signal stream, the method comprising:
detecting, by the wireless door sensor, a specified number of door transitions within a specified time period, and in response to said detecting:
disabling a door signal transition event processing routine;
enabling a timer-based door sensor signal processing routine, wherein the timer-based routine reads a door sensor signal status regardless of whether a door signal transition has occurred, and
re-enabling the door signal transition event processing routine in response to reading a same value for the door sensor signal status multiple times over a time duration, such multiple readings being indicative of the door position being stabilized.

### Claim 2 (depends on 1)

The method of claim 1 wherein the wireless door sensor is a wireless sensor node within a wireless personal area network (WPAN).

### Claim 3 (depends on 2)

The method of claim 2 wherein the WPAN is incorporated into a transportable refrigerated container system (“reefer”).

### Claim 4 (depends on 2)

The method of claim 2 wherein the wireless personal area network implements communication between a coordinator and the wireless sensor node according to a ZIGBEE RF4CE wireless personal area network communication protocol.

### Claim 5 (depends on 1)

The method of claim 1 wherein wireless door sensor includes a switch.

### Claim 6 (depends on 5)

The method of claim 5 wherein the switch is a magnetic switch.

### Claim 7

A wireless door sensor node for incorporation into a wireless personal area network, the wireless door sensor node including:
a switch facilitating generating a door sensor status signal;
a processor; and
a non-transitory computer readable medium including computer-executable instructions, executable by the processor, for managing the wireless door sensor node to avoid excessive sensor signal processing arising from a chattering door sensor signal stream, the method comprising:
detecting, by the wireless door sensor, a specified number of door transitions within a specified time period, and in response to said detecting:
disabling a door signal transition event processing routine,
enabling a timer-based door sensor signal processing routine, wherein the timer-based routine reads a door sensor signal status regardless of whether a door signal transition has occurred, and
re-enabling the door signal transition event processing routine in response to reading a same value for the door sensor signal status multiple times over a time duration, such multiple readings being indicative of the door position being stabilized.

### Claim 8 (depends on 7)

The wireless sensor node of claim 7 wherein the sensor is configured to sense a change in magnetic field in response to a change in an open/closed status of a door.

### Claim 9

A transportable refrigerated container system including:
a refrigeration system including a controller;
a wireless communication system configured as a wireless personal area network (WPAN), the WPAN comprising:
a wireless sensor node, configured to sense a status of a door in the refrigeration system and communicate the status of the door to a second node within the WPAN, the wireless sensor node comprising:
a switch facilitating generating a sensor status signal indicating the status of the door;
a processor; and
a non-transitory computer readable medium including computer-executable instructions, executable by the processor, for managing the wireless door sensor node to avoid excessive sensor signal processing arising from a chattering door sensor signal stream, the method comprising:
detecting, by the wireless door sensor, a specified number of door transitions within a specified time period, and in response to said detecting:
disabling a door signal transition event processing routine,
enabling a timer-based door sensor signal processing routine, wherein the timer-based routine reads a door sensor signal status regardless of whether a door signal transition has occurred, and
re-enabling the door signal transition event processing routine in response to reading a same value for the door sensor signal status multiple times over a time duration, such multiple readings being indicative of the door position being stabilized.