Geo-referencing identification (GRID) tag
11313972 · 2022-04-26
Assignee
Inventors
- Benjamin Schreib (Baltimore, MD, US)
- Michael House (Laurel, MD, US)
- Samuel McClintock (Williamsburg, VA, US)
- David Rein (Ann Arbor, MI, US)
- Navid Yazdi (Ann Arbor, MI, US)
Cpc classification
G01W1/02
PHYSICS
G06Q10/08
PHYSICS
G06K19/0723
PHYSICS
G01S5/0072
PHYSICS
H04W84/18
ELECTRICITY
G06K19/0717
PHYSICS
G06K7/10366
PHYSICS
G06Q10/087
PHYSICS
G01S19/03
PHYSICS
H04W4/70
ELECTRICITY
G01S19/49
PHYSICS
International classification
G01S19/03
PHYSICS
H04W84/18
ELECTRICITY
G01W1/02
PHYSICS
G01S5/00
PHYSICS
G06Q10/08
PHYSICS
H04W4/70
ELECTRICITY
G06K7/10
PHYSICS
G01S19/49
PHYSICS
Abstract
A system for tagging and tracking assets anywhere in the world under any environmental condition. Geo-Referencing Identification (GRID) tag, GRID satellite (GRIDSAT) tag and associated cloud infrastructure and user interface meet the objectives of a robust global tagging and tracking system. The GRID tag can be used to identify pieces of equipment or storage containers for low-value or aggregate equipment. GRID tags communicate with each other using a mesh radio in each tag. The GRIDSAT tag consists of a satellite modem, global positioning system (GPS) receiver, and mesh radio and can be used by itself for high-value items, large shipping containers, or vehicles and vessels to track and locate them, or used in concert with GRID tags that communicate with each other and with the GRIDSAT tag by means of mesh radio.
Claims
1. A geo-referencing Tag system for remote locating and tracking, the geo-referencing Tag system comprising: a plurality of data transmission tags, each tag comprising: a power source; a microcontroller; at least one environmental sensor; and a communication module configured to communicate with at least one satellite tag and one or more data transmission tags, and the at least one satellite tag, the at least one satellite tag being configured to be positioned proximate to the data transmission tags, and the at least one satellite tag being configured to communicate with the plurality of data transmission tags and route data via satellite which is generated by the data transmission tags to a Geographical Information System user interface, the at least one satellite tag comprising; a power source; a microcontroller; a GPS receiver; at least one environmental sensor; a satellite modem being configured to communicate with the satellite; and a communication module being configured to communicate with the plurality of data transmission tags, wherein the at least one satellite tag is configured to aggregate information obtained from a mesh network formed based on the data transmission tags and the at least one satellite tag, the information being generated by the data transmission tags, and wherein the at least one satellite tag is configured to supplement the aggregated information with location information comprising its GPS position and transmit the aggregated information via the satellite.
2. The geo-referencing Tag system of claim 1, wherein the data transmission tags comprise: an accelerometer as an environmental sensor; and a radio frequency module as a communication module for establishing the mesh network; and wherein the satellite tag comprises: a radio frequency module as a communication module for communicating with the mesh network and transmitting commands to the mesh network.
3. The geo-referencing Tag system of claim 2, wherein a particular tag is configured to become active based on detection of motion via the accelerometer, or wherein the particular tag becomes active based on a predefined interval elapsing or based on a command being received.
4. The geo-referencing Tag system of claim 2, wherein the mesh network between tags is automatically formed and information is transmitted at regular intervals between tags and to the Geographical Information System user interface.
5. The geo-referencing Tag system of claim 1, wherein output of the environmental sensors is included in affects communication between the tags.
6. The geo-referencing Tag system of claim 5, wherein the environmental sensors detect environmental factors selected from the group consisting of temperature, electromagnetic radiation, particle radiation, pH, turbidity and motion.
7. The geo-referencing Tag system of claim 1 configured to track ice floes wherein the data transmission tags comprise: a pressure sensor as an environmental sensor; a subsurface transducer for sending and receiving; and a Lamb/Rayleigh wave transducer as a communication module for transmitting a guided wave to other data transmission tags and the satellite tag, without a local field or fixed electrical, civil, mechanical, structural, or wireless infrastructure being required for operation; and wherein the satellite tag comprises: a Lamb/Rayleigh wave detector as a communication module for receiving guided waves and transmitting commands to the data transmission tags.
8. The geo-referencing Tag system of claim 7, wherein the at least one satellite tag further comprises hardware for mounting said tag onto ice.
9. The geo-referencing Tag system of claim 1, wherein the information obtained form the mesh network does not include location information.
Description
BRIEF DESCRIPTION OF THE FIGURES
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DETAILED DESCRIPTION OF THE INVENTION
(8) The following description is provided to enable any person skilled in the art to make and use the invention and sets forth the best modes contemplated by the inventors of carrying out their invention. Various modifications, however, will remain readily apparent to those skilled in the art, since the general principles of the present invention have been defined herein specifically to provide RFID asset management for remote locations.
(9) Quality Function Deployment (QFD) is a structured approach to defining customer needs or requirements and translating them into specific plans to produce products to meet those needs. In the case of the GRID and GRIDSAT tags, the initial requirements were both specific and derived from subsequent tests: Small; Inexpensive; Automatically inventory all response equipment in real time; Indicate location during storage and deployment; Maximize the use of commercial-off-the-shelf (COTS) parts; Compatible with the marine environment; Satellite communications for global coverage; Vibration power generator for increased functionality during equipment deployment; Real time updating of inventory database; Wireless Network.fwdarw.Mesh network for robustness (link healing); Range (mesh): 100-500 feet; Battery Life 6 months-2+ years (power management); Temperature range: −40° C. to 85° C.; Military standard 883 specifications for vibration and shock (durability); and IP67 packaging specifications (water resistance and durability).
(10) The present invention supports inventory, transit, staging, deployment, and response. Equipment and assets can be identified and tagged while in storage so that the user knows which assets are available and where. The GRID and GRIDSAT tag's low power storage mode allows intelligent power management, with timely communication. If an incident occurs that requires a response, the user can track assets as they are moved from inventory to a forward staging area. Through the mesh network, GRID tags can communicate through other GRID tags to a GRIDSAT tag, which then relays the entire message through the satellite communication network with location, time, identification, and status information to the mapping user interface or common operating picture. At the staging area, resources can be assigned and deployed into action. Once equipment, personnel, and other resources are deployed into the field during a response, the system automatically reports their information and location for ease of use to enhance situational awareness. Low power consumption enables tagging of equipment while in storage to allow for the identification and inventory of available resources. Resources at a staging area can be assigned and deployed to any user. GRID tags form a local mesh network and message to a GRIDSAT tag that automatically reports resource information to a remote management center for identification and tracking during a response.
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(12) The messages that can be passed between the GRID tags to the GRIDSAT tags and on to the satellite gateway are summarized as: GRID tag Message Format to GRIDSAT tag: A payload of User Datagram Protocol (UDP) packets are sent over the tag mesh network. UDP packet format and mesh protocol have routing and cyclic redundancy check fields, and are not duplicated in payload fields. Most communications on the mesh network are these tag beacon messages. GRIDSAT Message Format to cloud Infrastructure: The GRID tag beacon messages are aggregated along with the GRIDSAT tag message and sent from the GRIDSAT tag to the server over the Iridium satellite network to the cloud infrastructure for interpretation and further processing for final display on the mapping user interface. Multi-Block Packet Header: When a GRIDSAT message is larger than the Iridium's Short Burst Data (SBD) message payload of 340 bytes, the GRIDSAT sends the message in multiple SBD packets. Each packet has a 3-byte block header followed by up to 337 bytes of the message.
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(14) The GRID tag 10 uses the RF module 34 for all processing functions. The RF module 34 provides a multi-tasking environment that supports both a 6LoWPAN mesh network stack and application-specific tasks implementing GRID tag functions.
(15) The network stack is configured as a router node, allowing the GRID tag 10 to communicate on the network and route messages between other nodes and the GRIDSAT tag 14. The GRID tags 10 use network discovery to identify the strongest router signal and the closest GRIDSAT tag 14 to decide which network to join. The network is self-healing: when a GRID tag 10 loses contact with its router to the GRIDSAT tag 14, it returns to discovery mode to find a new router or new network to join.
(16) Table 1 (below) shows the internal sensors that will produce the signals needed for tag operation and power management.
(17) TABLE-US-00001 Sensor Interface Notes Motion Serial Peripheral Interface The accelerometer operates in low- (SPI) power motion detection mode. It INTR digital motion detect asserts INTR to interrupt and wake signal the RF module. It uses the motion wake-up to control switching from Low-Power Storage mode to Active mode. Battery Analog to Digital Converter The MCU module computes the battery voltage, compares it to a low threshold to detect low voltage, and sets a fault status.
(18) Firmware. The following functions were implemented in the tag firmware to enable mesh networking and the advanced battery power management required to meet the desired GRID tag functionality and performance. Network Stack Functions .Math. 802.15.4 Media Access Control (MAC) layer Network joining
Point-to-point communications
Protocols (UDP, Internet Protocol [IP], Internet Control Message Protocol [ICMP]) .Math. 6LoWPAN layer configured as a router
Maintain routing tables and neighbor lists
Route unicast messages through network
Rebroadcast broadcast and multicast messages GRID Tag Functions .Math. Initialize and configure network stack .Math. Initialize GRID tag functions .Math. In deployed (active) state
Periodically send GRID tag report to GRIDSAT tag (if joined to a network)
Read battery voltage
Process parameter, get and set messages from maintenance network
A switch to the storage state will be determined by the amount of time no motion is detected .Math. In Storage State
Periodically send beacon message
Time motion-detected signals to determine when to switch to deployed (active) state.
(19) Enclosure
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(21) The GRIDSAT tag architecture includes an MCU 32 to act as a border router host, providing the gateway between external communications and the mesh network GRID tags 10. It directly interfaces with the GRIDSAT tag sensors, GPS module 44, Iridium modem 42, and RF module 34.
(22) The RF module 34 is the same one used for the GRID tags 10, but runs different firmware. The RF module 34 functions as the border router node (coordinator), maintaining lists of joined tags, and sending network beacons to synchronize mesh communications. It interfaces with the MCU 32 over an asynchronous serial interface, and has a digital output interrupt signal (INTR) to wake the MCU 32 whenever the RF module 34 needs to communicate with the MCU 32. The MCU 32 has sensor inputs for battery voltage and the accelerometer and directly interfaces with them and the GPS module. Parameters define polling rates for each sensor and the calibration/conversion coefficients.
(23) Iridium Modem. The GRIDSAT tag 14 uses the Iridium 9603 modem module 42 for communications with the cloud server 24 and GIS interface 26 by periodically sending GRIDSAT Tag Domain Reports 16.
(24) Firmware and Algorithms. Firmware on the GRIDSAT tag 14 was designed to implement the mesh networking communication, satellite communication, and power management. The MCU 32 sleeps most of the time, but wakes to process messages from the RF module 34 and for periodic server update cycles. The server update cycle is activated whenever the MCU 32 has gathered the information needed to create the GRIDSAT Tag Domain Report 16, including checking system status and waiting for a GPS fix. The following are key MCU functions: MCU Handling of Messages from the RF Module: .Math. Receives GRID tag reports—update information in GRID tag table .Math. Receives join/drop notifications—update GRID tag table .Math. Receives battery level—update GRIDSAT status .Math. Receives motion detection—initiate timer to determine state change For each server update cycle, the MCU performs the following operations: .Math. Powers on GPS and waits for a stable fix, then powers off GPS .Math. Generates GRIDSAT report .Math. Powers on Iridium modem Waits for satellite detection
Connects to satellite and opens channel for communications
Sends GRIDSAT report using SBD (Iridium Short Burst Data) protocol
Waits for packet acknowledgment
Powers down Iridium modem .Math. Sleeps until the next server update cycle or message from RF module
(25) The RF module has the following functions: Network Stack Functions 802.15.4 MAC layer
Network joining
Point-to-point communications
IP protocols (UDP, IP, ICMP)
Sends network announcements for network discovery
Sends network beacon polls to synchronize network communication windows
6LoWPAN layer configured as a border router
Maintains routing tables and neighbor lists
Maintains table of all nodes joined to the network GRIDSAT Functions
Initializes and configures network stack
Initializes GRIDSAT functions
In deployed (active) state:
Passes to MCU notifications of GRID tags joining the network
Passes to MCU notifications of GRID tags dropping from the network
Passes to MCU all UDP packets (GRID tag reports, etc.) received from network
Sends over network all UDP packets (parameter get/set, etc.) received from MCU
Processes command messages from MCU for GRIDSAT functions (read battery voltage, etc.)
Sends notifications to MCU of motion detection
In Storage state
Periodically sends beacon message, otherwise radio is off
Sends notifications to MCU of motion detection
Periodically sends MCU reading of battery voltage
(26) Time Synchronization. The GRIDSAT tag 14 uses the GPS Coordinated Universal Time (UTC) time to set and maintain its real-time clock 40, which is GPS time plus the correction for leap seconds. It timestamps GRID tag 10 messages when received. It adds to sync beacons the current UTC time, which allows GRID tags 10 to maintain their real-time clock (RTC) 40. Therefore, network-wide RTC time is accurate to about one second.
(27) Firmware Segment for Controlling Iridium Modem Module. The MCU 32 communicates with the Satellite Modem module 42 over an asynchronous serial interface. Data packets are sent as SBD messages to the Iridium system. The Iridium gateway 20 sends the messages to the cloud server 24 and GIS interface 26 as Mobile Originated (MO) direct IP transfers.
(28) The payload for SBD messages is 340 bytes. This allows sending a GRIDSAT 14 message with 26 GRID tags 10 in a single packet. If a GRIDSAT network has more than 26 joined tags, then the GRIDSAT message is sent as a multi-block message.
(29) Both the GRID tag 10 and the GRIDSAT tag 14 do not have an external on/off switch and will operate autonomously and automatically. Both the GRID tag 10 and the GRIDSAT tag 14 operate in three different modes: (1) Low Power Storage Mode (LPSM). This mode is designed for the tags to minimize power consumption during storage. Motion sensor are monitored during LPSM. Storage beacon messages may be sent for inventory purposes. (2) Active Mode. This is the mode the tags operate during deployment. In this mode, the GRIDSAT tag 14 will act as a network-coordinator host to send sync beacons and manage GRID tags 10 in its network. The GRIDSAT tag 14 will also establish the satellite communication link and run a server update cycle with GPS fix. (3) Maintenance Mode. This mode can be initiated by issuing an addressed maintenance command message to a target tag. In this mode, the configuration parameters on the tag can be retrieved and set using commanding messages.
(30) The following Table 2 (below) compares Low Power Storage operation modes of the GRID tag and the GRIDSAT tag:
(31) TABLE-US-00002 GRID Tag GRIDSAT Tag Enter When there is no motion When there is no motion detected for a configurable detected for a configurable period of greater than 1 period of greater than 1 hour to greater than 1 week hour to greater than 1 week and tag is not joined to a and tag is not joined to a mesh network. mesh network. Configured Low Power End Node Low Power End Node As Network No activity No activity Status Powering down all of its Powering down all of its subsystems except the subsystems except the Motion Sensor. Motion Sensor. Operation The RF Module sets its Before the GRIDSAT tag sleep timer to the storage enters LPSM, it waits for the beacon period and monitors next sync beacon and sends the Motion Sensor. It sends a beacon with network an optional storage beacon shutdown indicator, so all of message at a rate the joined GRID tags will be configurable from 1 per able to also enter LPSM. hour to 1 per month. The RF Module sets its sleep timer to the storage beacon period and monitors the Motion Sensor. It sends an optional storage beacon message at a rate configurable from 1 per hour to 1 per month.
(32) The following Table 3 (below) compares Active operation modes of the GRID tag and the GRIDSAT tag:
(33) TABLE-US-00003 GRID Tag GRIDSAT Tag Enter Upon Exit of LPSM Upon Exit of LPSM Configured As Network router. A network coordinator host Discovery When not joined to a network, N/A running the tag's discovery process looking for an active network to join. Sync Beacon N/A RF Module sends network sync beacons every 1-5 minutes Operation The tag sleeps between active RF Module: windows and wakes to start an Maintains network tables of routes active window. and joined GRID tags based on During the active window, the tag acknowledgement to beacon. has the following operations: Sends notification to MCU when 1. The network stack handles GRID tag joins or drops from the routing and resending of traffic. network. 2. The network stack listens for a Sends received GRID tag Report sync beacon from its network Messages to MCU. router. When it gets the sync After end of active window, beacon, it responses with an listens for maintenance command ACK message; addressed to itself and enters MM. 3. Periodically the application level MCU: sends a GRID tag report message. Wakes 1-2 times per day to run a After end of active window, the tag Server Update Cycle. listens for a maintenance command Handles notification and report addressed to itself and enters message from RF Module to Maintenance Mode if such message maintain its GRID tag table. is received. Powers on GPS, waits for stable GPS fix (expected to be 20 to 500 seconds), then powers down. Powers on Iridium modem, waits for connection, sends GRIDSAT and GRID tag report, powers down modem. Total on time expected to be 6 to 22 seconds. Sleeps until next Server Update Cycle.
(34) The following Table 4 (below) compares Maintenance operation modes of the GRID tag and the GRIDSAT tag:
(35) TABLE-US-00004 GRID Tag GRIDSAT Tag Enter After receiving an addressed After receiving an addressed maintenance command maintenance command message. message. Configured As End Node End Node Network Commanding maintenance Commanding maintenance network network Operation Accept set and get parameter Accept set and get parameter message to allow message to allow configuration of the GRID configuration of the tag. GRIDSAT tag. Exit Either by command or when Either by command or when it drops from the it drops from the maintenance network. maintenance network.
(36) As shown in
(37)
(38) Cloud infrastructure provides the backend data acceptance from the satellite gateway, processing and interpreting key tag information such as location to a web-accessible map displayed for the end user.
(39) The Cloud-Based Data Server hardware that was chosen for this project is sufficient for prototyping and proof of concept. Because of Amazon web service's scalability, what is done on a small scale using the Amazon platform can readily be upgraded to support a larger, production-ready environment. The hardware chosen is suitable to support all software components of this project including, NginX, the Node Ingestion server, MongoDB database, and the web-mapping application. The Amazon Web Services data centers are staffed 24/7 by trained security guards, contain environmental systems to minimize the impact of disruptions, and span multiple geographic regions to provide resiliency to both manmade and natural disasters.
(40) GIS Software Application Package. After the NginX reverse proxy accepts the incoming requests from the satellite gateway, the GIS software application package 26, mentioned above, that consists of the node gateway receiver and processing server uses the JSON entity mapper to parse the GRIDSAT tag, produce Tag Domain Reports, and store the data in the MongoDB database deployed on the Amazon Web Services server. After the data are stored, they are immediately indexed and made available to search using the front end mapping application.
(41) Mapping API. The user interface is designed to provide all of the desired functionality while maintaining ease of use for novice users. Desired functionality is as follows: GRIDSAT tags viewable on a map; Visible status indication of GRIDSAT tags; Clicking GRIDSAT tags displays additional information about GRID tags; User can review the history details of the GRIDSAT tags.
(42) A “House of Quality” QFD (quality function deployment) was performed to assess factors affecting the quality of the system. Table 5 (below) shows the derived House of Quality, where Interrelationship Weightings indicate values for which a value of 1 represents Weak, a value of 3 represents Moderate, and a value of 9 represents Strong:
(43) TABLE-US-00005 Engineering Requirements GRID Tag Point-to-Point Deployment Physical Importance RF Communication Firmware Means Design Battery Power Tag Longevity Customer Requirements wt. 1 2 3 4 5 6 1 Mark Equipment Location 0.25 3 3 3 3 3 3 2 On Station >6-9 months 0.15 9 3 3 9 9 3 Compact Size 0.05 9 3 9 9 3 4 Compatible w/Marine Environment 0.15 3 9 9 3 3 5 Temperature Range (to −40 C.) 0.15 3 9 9 3 3 6 Ease of Deployment 0.05 9 9 7 Cost Effective 0.05 3 9 3 9 9 3 8 Communication Range 0.10 9 9 3 3 9 3 9 Maximum use of COTS Products 0.05 3 3 1 3 3 1 10 Initial Importance 1.00 4.65 2.70 5.00 5.25 4.95 3.65 Engineering Requirements GRIDSAT Tag Point-to-Point Deploy- RF Satellite GPS Firm- ment Physical Battery Tag Communication Communication Module ware Means Design Power Longevity Customer Requirements 7 8 9 10 11 12 13 14 1 Mark Equipment Location 3 3 9 3 3 3 3 3 2 On Station >6-9 months 9 9 9 3 9 9 3 Compact Size 9 9 9 3 9 9 3 4 Compatible w/Marine Environment 3 9 3 9 9 3 3 5 Temperature Range (to −40 C.) 3 9 3 9 9 3 3 6 Ease of Deployment 9 9 9 9 7 Cost Effective 3 9 9 9 3 9 9 3 8 Communication Range 9 9 3 9 3 3 9 3 9 Maximum use of COTS Products 3 9 9 3 1 3 3 1 10 Initial Importance 4.65 7.50 6.60 2.25 5.00 5.25 4.95 3.65
(44) Based the analysis from House of Quality, Satellite Communication received the highest technical priority. Satellite communication's importance comes from three major aspects: (1) It provides the critical link for data transfer between mesh network and the cloud server; (2) Integration of the satellite modem into GRIDSAT has impacts in form factor, size and cost; (3) Operation of satellite communication in the GRIDSAT tag is a main contributor for power consumption; therefore, selection and sizing of battery are affected.
(45) Essentially all of the system components are “off the shelf” making the system cost effective and easy to assemble. Table 6 (below) provide component information:
(46) TABLE-US-00006 Weight Cost (grams) ($) Key GRID Tag BOM Item 1 RF and MCU chipset with PA & LNA, <3 <19 JN5168-001-M06 2 Power regulator, TPS781 <0.5 <0.5 3 Power regulator, LD39100 <1 <0.7 4 Motion & acceleration sensor, ADXL362 <0.5 <4 5 Antenna, ANT-2.4-JJB <2 <2.20 6 Battery primary A cell Bobbin, LS17500 <22 <4.5 7 Enclosure <140 <15 Key GRIDSAT Tag BOM Item 1 Satellite module, Iridium 9603 11.5 <175 2 GPS module, MAX_7 <1 <59 3 RF and MCU chipset with PA & LNA, <3 <19 JN5168-001-M06 4 MCU, LPC11U68JBD48 <1 <4 5 Iridium antenna, IP.1621.25.4.A.02 10 <6.5 6 GPS antenna, FXP611.07.0092C <2 <14 7 Mesh antenna, ANT-2.4-JJB <2 <2.20 8 Motion & acceleration sensor, ADXL362 <0.5 <4 9 Power conversion IC, TPS63060 <0.5 <3.2 10 Power conversion IC, LTC3103 <0.5 <4 11 Power regulator, LP3962 <0.5 <3 12 Power regulator, TLV70233 <0.5 <0.5 13 Power regulator, TPS781 <0.5 <0.5 14 Battery primary 2 × D cell Spiral, ER34615M <220 <15 15 Enclosure <260 <18 Key Cloud Infrastructure BOM Item 1 Satellite Gateway, Iridium (DISA) N/A 0 2 Servers, Amazon Web Services, EC2 General N/A 33/ Purpose Previous Gen. m1.small + 10 GB month Elastic Block Store (EBS) @ 2.35 GHz 3 GIS software application package, Node N/A 0 w/Koop, Version 0.10.32 4 HTTP server and reverse proxy, NginX, N/A 0 Version 1.4.0 5 Mapping API, Leaflet, Version 0.6.4 N/A 0
(47) Table 7 (below) represents the GRID and GRIDSAT tags' estimated mean time to failure (MTTF). MTTF (Hours) is determined by adding up the total failure rates and calculating (1/(Total Failure Rates/1,000,000 hours)):
(48) TABLE-US-00007 Estimated Mean Time To Failure Analysis for GRID and GRIDSAT Tags Item No. Item Quantity Failure Rate (FPMH) GRID RF Module 1 1 MCU 1 0.1 Enclosure 1 3 Motion Sensor 1 1 Flash 1 0.1 Total Failure Rate 5.2 MTTF (Hours) 192,308 MTTF (Years) 21.95 GRIDSAT RF Module 1 1 GPS 1 1 MCU 1 0.1 Sat Modem 1 1 Enclosure 1 3 Motion Sensor 1 1 Flash 1 0.1 Total Failure Rate 7.2 MTTF (Hours) 138,889 MTTF (Years) 15.85
(49) The estimated MTTF are 21.95 years and 15.85 years for GRID Tag and GRIDSAT Tag, respectively. The estimations did not include the batteries for both tags. With the inclusion of a battery with 10 FPMH in the model for calculation will bring MTTF for GRID Tag to 7.51 years, which is 2-5× longer than the battery life. Similarly for GRIDSAT Tag, MTTF with battery will be 4.20 years, more than 4× of the battery life designed for this application.
(50) Table 8 below summarizes the mesh signal budget and link reliability between two adjacent mesh nodes (i.e. point-to-point mesh link) for GRID and GRIDSAT tags. The link budget is also derived for the case where transmit power amplifier (PA) and receive low nose amplifier (LNA) are added. The addition of PA and LNA provides a link reliability of greater than 99% over 1200 ft. (365.8 m) range for typical environment loss conditions due to multi-path, fading, orientation, enclosure, etc. In the high environment loss conditions which include an additional 20 dB loss over typical conditions caused by various effects, including ice formation, the 99% reliable range of 420 ft. (128 m) is obtained. The 99% reliable range for the tags without PA and LNA under typical loss conditions is 400 ft. (122 m).
(51) TABLE-US-00008 w/o PA & LNA With PA & LNA Mesh Link Budget Typical Lossy conditions Typical Lossy conditions (single hop) conditions (wet, thin ice, etc.) conditions (wet, thin ice, etc.) Tx Power 2.5 dBm 2.5 dBm 22 dBm 22 dBm Rx Sensitivity −95 dBm −95 dBm −100 dBm −100 dBm Tx/Rx Antenna Gain −1 dB −1 dB −1 dB −1 dB Tx Loss 2 dB 2 dB 2 dB 2 dB Propagation Loss 78 dB @ 300 ft. 78 dB @ 300 ft. 100 dB @ 100 dB @ (91.4 m) (91.4 m) 1000 ft. 1000 ft. (304.8 m) (304.8 m) Rx Loss 2 dB 2 dB 2 dB 2 dB Other environment 8 dB 18 dB 8 dB 28 dB related losses Link reliability Range <400 ft. Range <240 ft. Range <1200 Range <420 ft. >99% Range (122 m) (73.2 m) ft. (365.8 m) (128 m)
(52) Environmental testing included operation at temperature extremes, water immersion, shock, and vibration. The results are presented in the following paragraphs for both the GRIDSAT and GRID tags.
(53) Temperature. The Tenney BTRC (Benchmaster Temperature/Relative Humidity Test Chamber) environmental chamber was used to test the system from −50° C.) to 80° C. The mesh, GPS, and Iridium modem antennas were connected outside of the chamber with cables. The mesh network beacon rate was set to 10 seconds, and system functionality was verified by successful beaconing by the GRID tag to the GRIDSAT and reporting to the satellite by initiating a transmission through the GRIDSAT universal serial bus (USB) interface over time and temperature extremes. We employed Saft 17500 and Xeno XL-100F A-cell batteries for GRID tags in our tests that showed current delivery deterioration at temperatures above 75° C. which in some instances affected the tag's functionality. The GRIDSAT batteries Fanso ER34615M D-cell worked without any interruption in all the tests conducted up to 81° C., and all batteries operated successfully down to −50° C.
(54) GRIDSAT and GRID tags were both subjected to the water immersion test at greater than 1.1 meters. The temperature was at 25° C. plus or minus 5° C. for 15 minutes, 1 hour, and 12 hours in three separate tests, which all resulted in no leaks. A drop test (high gravity test) on concrete was performed. The GRID and GRIDSAT tags were dropped onto a concrete floor four times each from a height of 6 ft. (1.83 m) and no damage was observed. The devices were tested on an Unholtz-Dickie shaker system (Model 630) at the laboratories of the Electrical and Computer Engineering department of University of Michigan to simulate vibrational conditions. The peak acceleration was set to 5 g at the 20 to 2,000 Hz frequency range. After the vibration tests, the devices were opened for visual inspection and verified to be fully functional.
(55) The following claims are thus to be understood to include what is specifically illustrated and described above, what is conceptually equivalent, what can be obviously substituted and also what essentially incorporates the essential idea of the invention. Those skilled in the art will appreciate that various adaptations and modifications of the just-described preferred embodiment can be configured without departing from the scope of the invention. The illustrated embodiment has been set forth only for the purposes of example and that should not be taken as limiting the invention. Therefore, it is to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described herein.