Ultrasonic communication system

• US 10,447,410 B2
• Filed: 11/26/2014
• Issued: 10/15/2019
• Est. Priority Date: 12/02/2013
• Status: Active Grant

• Current Assignee: The Board of Trustees of Michigan State University (Michigan State University)
• Original Assignee: The Board of Trustees of Michigan State University (Michigan State University)
• Inventors: Biswas, Subir, Lorenz, Stephan, Dong, Bo, Huo, Qiong
• Primary Examiner(s): Hulka, James R
• Application Number:
  US15/039,243
• Publication Number:
  US 20170126332A1
• Time in Patent Office: 1,784 Days
• Field of Search: 367117
• CPC Class Codes: G08B 25/007 Details of data content structure of message packets; data protocols
• CPC Class Codes: G08B 25/009 Signalling of the alarm condition to a substation whose identity is signalled to a central station, e.g. relaying alarm signals in order to extend communication range
• CPC Class Codes: H04B 11/00 Transmission systems employing sonic, ultrasonic or infrasonic waves
• CPC Class Codes: H04L 7/0037 Delay of clock signal
• CPC Class Codes: H04L 7/02 Speed or phase control by the received code signals, the signals containing no special synchronisation information H04L7/0075 takes precedence
• CPC Class Codes: H04W 4/38 for collecting sensor information
• CPC Class Codes: H04W 4/70 Services for machine-to-machine communication [M2M] or machine type communication [MTC]
• CPC Class Codes: H04W 56/0015 one node acting as a reference for the others

Abstract

A sensor network includes a sink and multiple sensor nodes. The sink is coupled to a substrate and configured to transmit a periodic ultrasonic pulse on the substrate. A first one of the sensor nodes is coupled to the substrate. The first sensor node is configured to (i) receive the periodic ultrasonic pulse from the substrate, (ii) synchronize an internal clock of the first sensor node to the sink based on the periodic ultrasonic pulse, (iii) selectively detect an event in a region surrounding the first sensor node, and (iv) in response to detecting the event, transmit a first ultrasonic pulse toward the sink on the substrate.

Claims

1. A sensor network comprising:

a controller coupled to a substrate and configured to generate and transmit a periodic ultrasonic pulse on the substrate; and

a plurality of sensor nodes, wherein each of the plurality of sensor nodes is coupled to the substrate and wherein a first sensor node of the plurality of sensor nodes is configured to;

receive the periodic ultrasonic pulse from the controller via the substrate,

synchronize an internal clock of the first sensor node to the controller based on the received periodic ultrasonic pulse,

selectively detect an event in a region surrounding the first sensor node, and

in response to detecting the event;

generate a first ultrasonic pulse synchronized to the internal clock of the first sensor node, and

transmit the first ultrasonic pulse toward the controller on the substrate.

2. The sensor network of claim 1 wherein:

the periodic ultrasonic pulse has a first transmission range,

the first ultrasonic pulse has a second transmission range, and

the first transmission range is greater than the second transmission range.

3. The sensor network of claim 2 wherein:

the controller is configured to transmit the periodic ultrasonic pulse using a first voltage,

the first sensor node is configured to transmit the first ultrasonic pulse using a second voltage, and

the first voltage is greater than the second voltage.

4. The sensor network of claim 3 wherein the first voltage is approximately double the second voltage.

5. The sensor network of claim 1 wherein a second sensor node of the plurality of sensor nodes is configured to:

receive the first ultrasonic pulse via the substrate, and

in response to receiving the first ultrasonic pulse, transmit a second ultrasonic pulse toward the controller on the substrate.

6. The sensor network of claim 1 wherein the first sensor node is configured to:

determine an arrival time of a first mode of the periodic ultrasonic pulse at the first sensor node,

determine an arrival time of a second mode of the periodic ultrasonic pulse at the first sensor node, and

estimate a propagation delay of the periodic ultrasonic pulse from the controller to the first sensor node based on the arrival time of the first mode and the arrival time of the second mode.

7. The sensor network of claim 6 wherein the first sensor node is configured to adjust synchronization of the internal clock of the first sensor node based on the propagation delay.

8. The sensor network of claim 6 wherein:

the first mode is a symmetric mode, and

the second mode is an asymmetric mode.

9. The sensor network of claim 1 wherein:

the sensor network is spatially divided into a plurality of cells, and

each sensor node of the plurality of sensor nodes is configured to be assigned to one of the plurality of cells.

10. The sensor network of claim 9 wherein each sensor node of the plurality of sensor nodes is assigned to one of the plurality of cells during a pre-programmed setup phase of the sensor network.

11. The sensor network of claim 1 further comprising an actuator node including a physical actuator.

12. The sensor network of claim 11 further comprising a plurality of actuator nodes including the actuator node.

13. The sensor network of claim 11 wherein the physical actuator is configured to operate in response to a command from the controller.

14. The sensor network of claim 11 wherein the physical actuator is configured to operate in response to data received from one or more of the plurality of sensor nodes.

15. The sensor network of claim 14 wherein the actuator node is configured to receive the data directly from the one or more of the plurality of sensor nodes, bypassing the controller.

16. The sensor network of claim 1 wherein the first sensor node includes an ultrasonic transducer coupled to the substrate.

17. The sensor network of claim 16 wherein the ultrasonic transducer includes a piezoelectric element.

18. The sensor network of claim 16 wherein:

the ultrasonic transducer is located between a first side of the substrate and a first magnet, and

a second magnet is located on an opposite side of the substrate from the ultrasonic transducer.

19. The sensor network of claim 18 wherein the ultrasonic transducer is secured to the first magnet with an epoxy.