Methods for anti-collision and multiple access in RFID communications

• US 8,805,649 B2
• Filed: 02/04/2009
• Issued: 08/12/2014
• Est. Priority Date: 02/04/2009
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Rao, Samantha, Berkcan, Ertugrul, Andarawis, Emad, Delgado, Eladio
• Primary Examiner(s): Suglo, Janet
• Assistant Examiner(s): DALBO, MICHAEL J
• Application Number:
  US12/365,844
• Publication Number:
  US 20100198560A1
• Time in Patent Office: 2,015 Days
• Field of Search: 702/188
• US Class Current: 702/188
• CPC Class Codes: G08C 15/02 simultaneously, i.e. using frequency division
• CPC Class Codes: G08C 15/06 successively, i.e. using time division
• CPC Class Codes: H04Q 2209/10 using a centralized architecture
• CPC Class Codes: H04Q 2209/30 using a wired architecture
• CPC Class Codes: H04Q 2209/40 using a wireless architecture
• CPC Class Codes: H04Q 2209/47 using RFID associated with sensors
• CPC Class Codes: H04Q 2209/756 where the polling of the sub-stations is cyclic, e.g. round-robin
• CPC Class Codes: H04Q 2209/88 Providing power supply at the sub-station
• CPC Class Codes: H04Q 2209/883 where the sensing device enters an active or inactive mode
• CPC Class Codes: H04Q 2209/886 using energy harvesting, e.g. solar, wind or mechanical
• CPC Class Codes: 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

Abstract

A monitoring system for monitoring one or more operating conditions of a structure such as an aircraft, method of operating a system for monitoring one or more operating conditions of the structure, and a sensor node for use in a monitoring system for monitoring one or more operating conditions of the structure, are provided. An example of a monitoring system can include a plurality of sensor nodes coupled to the structure and a controller for monitoring the sensor nodes. Each sensor node can include a communications interface including memory storing a plurality of sensor node communication protocol attributes used for communicating with the controller.

Claims

1. A distributed monitoring system for monitoring one or more operating conditions of an aircraft structure, comprising:

a plurality of sensor nodes coupled to an aircraft structure, each sensor node comprising;

a power supply positioned to scavenge energy from an immediate environment in which the aircraft structure is located during operational employment of the structure;

a sensor operably coupled to the power supply for sensing one or more operating conditions of the aircraft structure in the immediate environment; and

a sensor communications interface operably coupled to the power supply to utilize the scavenged energy and to the sensor for communicating the sensed operating conditions of the aircraft structure, the communications interface comprising a memory containing a plurality of sensor node communication protocol attributes, the sensor node communication protocol attributes including a fixed center frequency for communicating sensed operating conditions from the sensor node and a fixed time delay for communicating the sensed operating conditions from the sensor node, the fixed center frequency being the same center frequency as that of at least one other of the plurality of sensor nodes and different than at least one other of the plurality of sensor nodes, the fixed frequency being unique for each sensor node having a same time delay to prevent collisions between sensor nodes having the same time delay, the fixed time delay being unique for each sensor node having the same center frequency to prevent collisions between the sensor nodes having the same center frequency;

a communication network operably coupled to the sensor nodes; and

a central controller housed within the aircraft structure and operably coupled to the communication network for monitoring the sensor nodes, the controller comprising a controller communications interface comprising a memory containing one or more controller communication protocol attributes, the controller further configured an initial handshake with the sensor nodes to receive or exchange data to acquire or to provide both the fixed center frequency and fixed time delay communication protocol attributes to be used between the controller and each of the respective plurality of sensor nodes to communicate sensed operating conditions to the controller.

2. The system of claim 1, wherein the sensor node communication protocol attributes further comprise a unique identifier for the sensor node.

3. The system of claim 1,

wherein the sensor communications interface of at least some of the sensor nodes comprises a plurality of directional antenna to further provide space division multiplexing;

wherein the controller communications interface comprises a plurality of directional antennas to receive data therefrom; and

wherein the controller further comprises a receiver and a schedule generator configured to identify the directional antenna to be used during operation of the receiver.

4. The system of claim 1, wherein the controller communication protocol attributes comprise the fixed center frequencies for communicating with and receiving information from the sensor nodes and the fixed time delays for receiving information from the sensor nodes, and wherein the controller is configured to transmit a sensor information query to each of the plurality of sensor nodes, and to await receipt of the sensor information separately from each of the sensor nodes receiving the sensor information query, the fixed time delays determined by the controller and provided to the respective sensor nodes as part of the initial handshake.

5. The system of claim 4, wherein the controller communication protocol attributes comprise unique identifiers for the sensor nodes.

6. The system of claim 1, wherein the central controller includes a transceiver, a controller operably coupled to the transceiver, an identification (ID) generator for generating and maintaining a database of IDs for each of the plurality of sensor nodes, and a schedule generator providing the fixed center frequency and fixed time delay of each sensor node of the plurality of sensor nodes.

7. The system of claim 1, wherein each sensor node is configured to communicate with the controller during the initial handshake such that each of the plurality of sensor nodes and the controller collectively determine the respective communication protocol attributes to be used via an arbitration process.

8. The system of claim 1, wherein the aircraft structure comprises an aircraft fuselage.

9. The system of claim 1, wherein the controller communication protocol attributes comprise each of the following:

the fixed time delays for receiving information from the sensor nodes;

unique identifiers for the sensor nodes; and

the fixed center frequencies for communicating with the sensor nodes.

10. The system of claim 9, wherein the fixed time delays and the fixed center frequencies are assigned by the controller during the initial handshake.

11. The system of claim 9, wherein the fixed time delays and the fixed center frequencies are assigned during the initial handshake as part of an arbitration process.

12. The system of claim 9, wherein the fixed time delays and the fixed center frequencies are assigned during the initial handshake according to a preset determination that the controller or the sensor nodes will determine the fixed center frequency to be used during the initial handshake between the controller and each respective sensor nodes.

13. The system of claim 3, wherein the controller communications interface comprises a plurality of directional antennas to further provide space division multiplexing.

14. The system of claim 13, wherein the sensor directional antenna to be employed for communicating information from one or more of the plurality of sensor nodes varies during operation of the system.

15. The system of claim 14, wherein the directional antenna to be employed for communicating information from the one or more sensor nodes varies during operation of the system according to a predetermined variance schedule.

16. A method of operating a system for monitoring one or more operating conditions of an aircraft structure, comprising:

providing power at a plurality of sensor nodes located around an aircraft structure through operational employment of the structure, the nodes configured to scavenge energy from an immediate environment in which the structure is located during operational employment of the structure;

storing sensor node communication protocol attributes within each of the sensor nodes, the communication protocol attributes including a fixed center frequency and a fixed time delay, the fixed frequency being unique for each sensor node having a same time delay to prevent collisions between sensor nodes having the same time delay, the time delay being different among respective sensor nodes for each sensor node having a same fixed center frequency to prevent collisions between sensor nodes having the same time delay;

each sensor node using the power to sense one or more operating conditions of the aircraft structure at the sensor node;

performing an initial handshake with each of the sensor nodes to receive or exchange data to acquire or to provide both the fixed center frequency and fixed time delay protocol communication attributes to be used between the central controller and each of the respective plurality of sensor nodes;

transmitting a query to the plurality of sensor nodes from the central controller; and

in response to the query, each sensor node transmitting the sensed operating conditions from the respective sensor node to the central controller as a function of the sensor node communication attributes using scavenged energy to communicate sensed operating conditions to the controller.

17. The method of claim 16, wherein the sensor node communication protocol attributes further comprise a unique identifier for the sensor node.

18. The method of claim 16,

wherein transmitting the sensed operating conditions from the sensor nodes to the central controller comprises transmitting the sensed operating conditions from the plurality of sensor nodes to the central controller in a particular direction;

and

wherein the method further comprises the step of generating a schedule to identify a directional antenna to be used during operation of a controller receiver.

19. The method of claim 16, wherein controller communication protocol attributes utilized by the central controller comprise the fixed center frequencies for communicating with and receiving sensed operating conditions from the sensor nodes and the fixed time delays for receiving sensed operating conditions from the sensor nodes, and wherein the method further comprises awaiting receipt of the sensor information separately from each of the sensor nodes receiving the query, the fixed time delays determined by the controller and provided to the sensor nodes as part of the initial handshake.

20. The method of claim 19, wherein the controller communication protocol attributes comprise unique identifiers for the sensor nodes.

21. The method of claim 18, wherein transmitting a query to the sensor nodes from a central controller comprises transmitting a query to the sensor nodes from the central controller in one or more particular directions.

22. The method of claim 16, wherein the aircraft structure comprises an aircraft fuselage.

23. The method of claim 16, wherein the central controller includes a transceiver, a controller operably coupled to the transceiver, an identification (ID) generator for generating and maintaining a database of IDs for each of the plurality of sensor nodes, and a schedule generator providing the fixed center frequency and fixed time delay of each sensor node of the plurality of sensor nodes.

24. The method of claim 16, wherein each sensor node is configured to communicate with the controller during the initial handshake such that each of the plurality of sensor nodes and the controller collectively determine the respective communication protocol attributes to be used via an arbitration process.

25. The method of claim 16, wherein the fixed time delays and the fixed center frequencies are assigned to each of the plurality of sensor nodes during the initial handshake.

26. The method of claim 16, wherein the fixed time delays and the fixed center frequencies are assigned during the initial handshake as part of an arbitration process.

27. The method of claim 16, wherein the fixed time delays and the fixed center frequencies are assigned during the initial handshake according to a preset determination that the controller or the sensor nodes will determine the fixed center frequency to be used during the initial handshake between the controller and each respective sensor nodes.

28. The method of claim 16, wherein transmitting the sensed operating conditions from the sensor nodes to the central controller comprises transmitting the sensed operating conditions from the plurality of sensor nodes to the central controller in one or more particular directions.

29. The method of claim 16, wherein transmitting the sensed operating conditions from the plurality of sensor nodes to the central controller comprises transmitting the sensed operating conditions from the plurality of sensor nodes to the central controller in different ones of the particular directions.

30. The method of claim 16, wherein transmitting the sensed operating conditions from the plurality of sensor nodes to the central controller comprises transmitting the sensed operating conditions from the plurality of sensor nodes to the central controller in different ones of the particular directions according to a predetermined schedule.

31. A sensor node for use in a distributed monitoring system for monitoring one or more operating conditions of an aircraft structure, comprising:

a power supply positioned to scavenge energy from an immediate environment in which an aircraft structure is located during operational employment of the structure;

a sensor operably coupled to the power supply for sensing one or more operating conditions of the aircraft structure in the immediate environment; and

a sensor node communications interface operably coupled to the power supply to utilize the scavenged energy and to the sensor for communicating the sensed operating conditions of the aircraft structure, the communications interface comprising a memory containing one or more sensor node communication protocol attributes, and a plurality of directional antennae to provide for space division multiplexing,

the sensor node communication protocol attributes including a fixed center frequency for communicating the sensed operating conditions from the sensor node, and a fixed time delay for communicating sensed operating conditions from the sensor node, the fixed center frequency being the same center frequency as that of at least one other of a plurality of other similarly configured sensor nodes and substantially different than at least one other of the plurality of sensor nodes, the fixed time delay being unique for each node having the same center frequency to prevent collisions between the other similarly configured sensor nodes having the same center frequency,

the sensor node configured to communicate sensed operating conditions of the aircraft structure to a central controller housed within the aircraft structure, and to communicate with the central controller during an initial handshake such that the sensor node and each of the plurality of sensor nodes and the controller collectively acquire or provide both the fixed center frequency and fixed time delay communication protocol attributes to be used between the controller, the sensor node, and each of the plurality of other similarly configured sensor nodes via an arbitration process, the sensor node configured to transmit the sensed operating conditions to the central controller using the scavenged energy.

32. The sensor node of claim 31, wherein the sensor node communication protocol attributes further comprise a unique identifier for the sensor node.

33. The sensor node of claim 31, wherein the sensor node communication protocol attributes comprise each of the following:

the fixed time delay for transmitting information from the sensor node;

a unique identifier for the sensor node; and

the fixed center frequency for communicating with the sensor node.

34. The sensor node of claim 31, wherein the directional antenna used for communicating information from the sensor node varies during operation of the system.

35. The sensor node of claim 34, wherein the directional antenna used for communicating information from the sensor node varies during operation of the system on a random basis.

36. The sensor node of claim 34, wherein the directional antenna used for communicating information from the sensor node varies during operation of the system according to a predetermined variance schedule.