DUAL MODE DATA COMMUNICATION FOR MONITORING AND DIAGNOSTICS OF REMOTE ASSETS

Abstract: A network communication system and method for monitoring and transferring diagnostic data between a remote asset (10) and a central monitoring facility (15) wherein the system comprises a data gathering module (16), an electronic storage device (19) located at the remote asset (10) to store the data, respective network interfaces (14, 18) located at the remote asset (10) and the monitoring facility (15), a processor (17) to manage sending and receiving of the data, a packet switched network (25), a circuit switched network (40), and a plurality of communication states (21, 22, 23, 34) interrelated with one another based on a predetermined communication protocol (7) wherein the communication system transitions between the packet switched network (25) and the circuit switched network (40) depending upon which communication state of the communication states is in use.

Description: DUAL MODE DATA COMMUNICATION FOR MONITORING AND DIAGNOSTICS OF REMOTE ASSETS BACKGROUND OF THE INVENTION The present invention relates to communication systems, and more particularly a communication system applicable for both mobile and fixed site remote assets, such as locomotives, to communicate with a central monitoring facility for exchange of status and monitoring diagnostics data. In communication systems, such as the Internet, data communication networks link end points with a series of nodes. Data transmitted through the network traverses interconnecting nodes to reach its destination. In this manner, the network of nodes circumvents the need for individual and permanent connection paths between all possible end points of the data network. Switching refers to the manner in which data traverses the network of nodes. Current engineering practice employs two types of network switching mechanisms, either circuit or packet switching. Transportation of data over a communication link is defined by a set of rules known as a protocol. A protocol stack is a group or "family" of protocols, each pertaining to a specific aspect of the data exchange task. The standard reference model for communication based upon standard interconnection protocol stack is the Open System Interconnection Reference Model (known as "OSI"). Standardized by the International Organization for Standardization (known as "ISO"), this model does not assume any specific system architecture nor does it require a particular implementation. Circuit switching implies that a series of interconnecting nodes linking transmit and receive end points are identified and reserved for the duration of the transfer session. Each circuit requires signaling to establish the connection, known as a call. The signaling is maintained for the duration of the call and is disconnected at the completion of the session. Circuit switching creates temporary but dedicated paths between transmit and receive end points. The only delays encountered with such a transmission path are those associated with establishment of the circuit and propagation over the circuit. For a circuit switched data link, Link, Network, Transport, Session, Presentation and Application protocol layers (according to the OSI model) are determined by the network end-points, allowing for greater implementation flexibility. The characteristics of a circuit switched communication link lend themselves to the efficient transfer of bulk data (i.e. file transfers). A packet switching network does not establish such dedicated circuits. Rather, a packet switching network forwards individual segments of data from one node to another. Each data packet contains identification, control, and user data information. In such a network, each node functions as both a switch and a queue which receives, holds, and forwards data packets as quickly as possible. A goal of such a network configuration is to exploit the burst-nature and short size of data packets to allocate network resources only when data is available and its transfer required. This network architecture affords transitory connection with end points and allows sharing of network links, ports, and routes between many users. A packet switched network typically consists of a multiplicity of nodes permitting multiple routes to a desired destination. The delay of a packet network is directionally proportional to the size of the network, the number of nodes that must handle a packet in transit, amount of traffic placed on the network by other users/nodes, and the processing required at each node. Protocols for packet data networks are typically fixed at the Physical, Link, Network, and Transport Layers. The characteristics of packet switched communication links lend themselves to the exchange of short, bursty, data messages. An application area involving the exchange of large, bulk data as well as short, bursty messages is the remote monitoring of mobile or transportable assets. Examples of such assets include containers, rail cars, trailers, power generators, medical diagnostic equipment, as well as automobiles, trucks and locomotives. Remote monitoring of such assets seeks to maintain an awareness of asset operational status, location, and characteristic performance data. The mobility of these assets favors the use of wireless communication links. The design of a wireless communication architecture to support remote monitoring systems typically involves a trade-off between the use of packet switched links offering low latency exchange of small, frequently occurring status/location messages versus the use of circuit switched links providing higher throughput and protocol flexibility for transfer of accumulated bulk data files and establishment of interactive command sessions. While the economics of wireless service costs tend to limit remote monitoring applications to the use of either a circuit or packet based channel, application performance requirements are often satisfied only by a wireless architecture employing switched, dual-mode (i.e. packet and circuit) data communication links. U.S. Patent Number 5,729,544 and U.S. Patent Number 4,539,676 appear to demonstrate data switching systems. It is believed that the '544 patent utilizes either a circuit switched channel or a packet switched channel to transmit data based upon contents of the data stream. The '544 patent appears to determine whether to use a circuit switched channel or a packet switched channel based solely upon the length of the message, i.e., by using header information from a specific protocol, TCP, within the Transport Layer to trigger communication mode switching. U.S. Patent No. 4,539,676 appears to employ communication mode switching by using data bits set by the Physical Layer of the OSI model. Remote monitoring of a locomotive presents significant challenges as such an asset's utilization modes fit that of a mobile, transportable and, at least temporarily, fixed site asset. Furthermore, a locomotive is comprised of a multitude of subsystems, controllers, computers, and sensors each generating a significant quantity of status messages and bulk operational data. While it is believed that U.S. Patent No. 5,845,272 details a system for isolating failures in a locomotive based upon this multitude operational performance data, there is still a need to collect, store, and exchange the bulk and status message data with a central monitoring facility at a higher cyclic rate than normal monitoring wherein the system does not determine the switched channel to use based solely upon the length or type of message sent. Such an approach could also result in a significant increase in efficiency for the management of remote assets as a packet network permits continuous and parallel monitoring of status from multiple assets while a circuit network connection provides dedicated information exchange with an individual asset. Establishment of a dedicated circuit connection only when its functionality is required allows the circuit switched network resource to be shared by an entire fleet of assets. Maintenance of packet network resources affords the ability to remain in contact with the entire asset fleet while servicing information exchange needs of individual fleet members. SUMMARY OF THE INVENTION This invention can be directly applied to the management of locomotives. As remote and mobile assets, locomotives require wireless communication links with wide coverage areas. Transmission of information is accomplished over a dual mode communication system where the dual modes are a circuit switched network and a packet switched network. The present invention is comprised of sensor outputs used to gather system status and health data of a locomotive, remote asset. This data is stored in an electronic database that is managed by an on-board computer. The locomotive also has a transceiver where data is transmitted to and information is received from a central monitoring facility. This invention leverages the Application Layer of the Open System Interconnection Model and a set of system states to determine whether it sends and receives using a packet switched network or a circuit switched network. Utilization of the Application Layer affords communication switching based upon a desired transmission functionality. The present invention defines four system states for communication between the central monitoring facility and remote assets. Both the central monitoring facility and the individual remote asset can initiate transitions between these states. The four states are Asset Monitoring State, Help State, Asset Diagnostics State, and Polling State. While in the Asset Monitoring State, a packet switched network is employed. Locomotives periodically transmit short status messages consisting of subsystem health indicators, GPS position, wireless coverage availability, etc. to the central monitoring facility. On a periodic basis the Polling State is entered via the packet network. This state allows the central monitoring facility to convey its desire for retrieval of fault logs and controller data in order to monitor engine performance and predict system failures. Fault trigger thresholds are defined within the locomotive system controllers. A transition to the Help State is conveyed from the locomotive via packet network if these thresholds are exceeded during normal locomotive operation. Both the Polling and Help States utilize the packet switched, wireless network. A circuit switched network is employed during the Asset Diagnostic State. In this state, bulk data consisting of asset controller, monitor, and/or sensor information may be retrieved from the remote asset by the central monitoring facility for analysis and diagnosis. This state also permits the download of application or operating system software modifications from the central monitoring facility to remote asset. In addition, the central monitoring facility may initiate an interactive terminal session with the asset to take corrective action or reconfigure the asset. Data exchanged during such an interactive session tends to be transactional in nature, requiring the combination of high data throughput and low latency often available only via circuit switch connection in order to maintain the interactive user's satisfaction. Upon completion of the Asset Diagnostic State, both network end-points return to Asset Monitoring State and the packet switched network. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a simplified schematic drawing of a dual mode communication system that carries both circuit switched and packet switched networks for monitoring and diagnostics of a fleet of locomotives. FIG. 2 illustrates a plurality of sensors interfaced with a computer which is capable of electronically storing sensor data, and a transceiver aboard a locomotive. FIG. 3 is an exemplary illustration of the Open System Interconnection (OSI) reference model for data communication protocol layers. FIG. 4 depicts the application oriented state diagram for the present invention. FIG. 5 illustrates the transfer of data during an Asset Monitoring State, Help State, and Polling State. FIG. 6 illustrates the transfer of data during an Asset Diagnostic State. DESCRIPTION OF THE INVENTION FIG. 1 illustrates a simplified schematic drawing of a dual mode communication system that carries both circuit switched and packet switched networks for monitoring and diagnostics of a fleet of locomotives. In the embodiment of FIG. 1, the present invention allows simultaneous communication between each locomotive or remote asset 10 in a fleet 9 of locomotives and a central, or remote, monitoring facility 15 via a satellite link 20. The satellite link 20 affords both circuit switched network 40 and packet switched network 25 connectivity to the remote asset 10. Though not illustrated, communications between a remote asset 10 and a central monitoring facility 15 may be accomplished with a terrestrial, wired network running between the remote asset 10 and monitoring facility 15 for connecting to a packet or circuit network when the remote asset 10 is in close proximity of the monitoring facility 15 or annex facility. Examples of such annex facilities include fuel depots, and maintenance facilities. FIG. 2 illustrates a plurality of data gathering modules or sensor modules 16 interfaced with a computer which is capable of electronically storing sensor data and facilitates transferring and receiving of said data, and a transceiver aboard a locomotive. Examples of sensor modules 16 aboard the locomotive or remote asset 10, include, but are not limited to fuel flow sensor modules, oil pressure sensor modules, oil filter sensor modules, current sensor modules, voltage sensor modules, temperature sensor modules, and global positioning system (GPS) receiver. The readings or outputs from the sensor modules 16 are fed into a computer or processor 17 where the information is stored in an electronic storage database or device 19 and then, depending on a state of a communication system, transmitted through a transceiver 18 to the remote monitoring facility 15 either over a packet switched network or a circuit switched network. The remote monitoring facility 15 receives the information through a transceiver 14 via a satellite link 20. The transceiver 14 may be located at the remote monitoring facility 15 or on the premises of the wireless network service provider and a terrestrial, wired network, such as the public switched telephone network (PSTN), used to connect to the remote monitoring facility 15. Though not shown, the remote monitoring facility includes a computer to facilitate the sending and receiving of data, and additional systems to generate data to send to the remote asset and to analyze the data received from the remote asset. By way of illustration, FIG. 3 is an exemplary illustration of the Open System Interconnection Model (OSI) model for data communication protocol layers. The OSI includes seven layers; Physical Layer 1, Data Link Layer 2, Network Layer 3, Transport Layer 4, Session Layer 5, Presentation Layer 6, and Application Layer 7. The present invention selects a data communication network by utilizing the Application Layer 7 which results in a more efficient communication network. FIG. 4 depicts the application oriented state diagram for the present invention. This figure reflects the transitions between states and differentiates those transitions initiated by the remote asset 10 from those initiated by the central monitoring facility 15. Transitioning at 60 from an Asset Monitoring State 21 to a Polling State 23 is initiated by the central monitoring facility 15. Transitioning at 62, 64 from the Polling State 23 to either the Asset Monitoring State 21 or an Asset Diagnostic State 34 is also initiated by the central monitoring facility 15. Transitioning at 66 from the Asset Monitoring State 21 to a Help State 22 is initiated by the remote asset 10. Transitioning at 68, 70 from the Help State 22 to either the Asset Monitoring State 21 or Asset Diagnostic State 34 is also initiated by the remote asset 10. Transitioning at 72 from the Asset Diagnostic State 34 to the Asset Monitoring State 21 is initiated by the central monitoring facility if the Asset Diagnostic State 34 was reached by going through the Polling State 23. Transitioning 74 from the Asset Diagnostic State 34 to the Asset Monitoring State 21 is initiated by the remote asset 10 if the Asset Diagnostic State 34 is reached by going through the Help State 22. The Asset Monitoring State, Polling State 23, and Help State 22 operate in a packet switched network 25. The Asset Diagnostic State 34 operates in a circuit switched network 40. FIG. 5 illustrates the transfer of data during the Asset Monitoring State 21, Help State 22, and Polling State 23. While in any of these states, messages are transmitted over the packet switched network 25. In the Asset Monitoring State 21, also known as the default state, short messages 30, 32 containing monitoring and/or control data, such as speed, temperature, subsystem health via Go/NoGo flags, or geographic position determined by using the global positioning system (GPS), are exchanged between the locomotive, or remote asset 10, and the central monitoring facility 15. The remote asset 10 may also communicate a desire to change its current system state to the central monitoring facility 15. Use of the packet switched network 25 for this state allows all members of the asset fleet 9 to transmit status messages at will, without requiring the schedule and establishment of a dedicated connection with the central monitoring facility 15. Since the central monitoring facility 15 exists as a peer end point on the packet network, it is also able to send status messages or state transition requests to an individual asset 10. In the Help State 22, the remote asset 10 sends a message 30 to the central monitoring facility 15 indicating a need for assistance as fault indicator occurred. In general, the central monitoring facility 15 will send an acknowledgment message 32 at which time both the remote asset 10 and the central monitoring facility 15 will transition to the Asset Diagnostic State 34, illustrated in FIG. 6. More specifically, in this state, based on previously defined events, the remote asset 10 transmits a status message 30 to the central monitoring facility 15 requesting assistance in the form of data retrieval and diagnosis. If the severity of the previously defined event dictates, the asset 10 and central monitoring facility 15 will negotiate information required to establish a dedicated, circuit switched connection. The negotiated information might include a connection delay period, a phone number for the asset 10 to use to call the central monitoring facility 15, or the type of circuit connection that the central monitoring facility 15 should employ to reach the remote asset 10 (i.e. cellular, satellite, terrestrial phone networks). The central monitoring facility 15 acknowledges this "Help" request and both the remote asset 10 and central monitoring facility 15 transition to the Asset Diagnostic State 34. The Polling State 23 may be initiated with remote asset fleet members 10 on a periodic basis. An example would be initiate the daily retrieval of operational fault logs from a locomotive 10. The Polling State 23 may include a request for an immediate status message containing a specific variable or the same content as periodically generated by the asset during the Asset Monitoring State. In other words, the Polling State can be used to force an immediate status update at an interval other than the periodic interval of the Asset Monitoring State. Depending upon the central monitoring facility's polling purpose, a transition to the Asset Diagnostics State 34 may be negotiated in order to leverage the benefits of the circuit switched connect for asset data investigation and retrieval. Such a transition from Polling State 23 to Asset Diagnostic State 34 may also be triggered to facilitate the download of application or operating system software upgrades to the remote asset 10. To command a transition from Polling State 23 to Asset Diagnostic State 34, the central monitoring facility 15 first sends a message 32 to the remote asset 10 indicating a desire to retrieve bulk data from the remote asset 10 or a desire for an interactive terminal session for, as example, to download software upgrades to the remote asset 10. The remote asset 10 will acknowledge this request with a second message 30. At this time both the remote asset 10 and central monitoring 15 will transition to the Asset Diagnostic State 34. FIG. 6 illustrates the transfer of data during the Asset Diagnostic State 34. While in this state a circuit switched network 40 is utilized for exchange of bulk data 35, 37 and/or establishment of an interactive session 38, 39. Generally, bulk data 35 is transferred from the remote asset 10 to the central monitoring facility 15. Occasionally, such as when upgrading software, bulk data 37 is sent from the central monitoring facility 15 to the remote asset 10. Interactive troubleshooting steps or operational configuration may be performed by the central monitoring facility 15 in this state. When the bulk data transfer is complete, the invention returns to the Asset Monitoring State 21. Use of the circuit switch network for this state affords lower latency and higher data throughput rates, benefiting both bulk data exchange and interactive sessions. Circuit switch communication resources promise cost savings for transfer of bulk data versus packet networks, especially when wireless communication networks are employed. One implementation of this invention is with the use of mobile satellite services based upon L-band geostationary satellites. The Asset Diagnostic State 34 can be implemented using TCP/IP and PPP protocols over circuit switch data satellite networks such as those operated by Motient and TMI Communications. Asset Monitoring 21, Help 22 and Polling 23 States are possible with packet data satellite networks, such as those operated by Motient, Norcom Networks, and TMI Communications. Use of a mobile satellite terminal, transceiver 18, such as the Westinghouse Series 1000 and its HVDM software, allows an on-board locomotive computer 17 to interface with both circuit and packet communication links. This example presents but a single embodiment of the present invention. By utilizing an application orientated approach to switching between circuit and packet networks, significant cost, efficacy, and capacity benefits are realized when monitoring a fleet of remote assets. Numerous variations, changes and substitutions will occur to those of skill in the art without departing from the invention herein. For example, simply as an illustration, the invention herein can be applied to individual entities in a fleet of any remote assets, such as a fleet of trucks. Accordingly, it is intended that only the spirit and scope of the appended claims limit the invention.

Claims: CLAIMS: WHAT IS CLAIMED IS: 1. A network communication system for transferring data in the form of computer-readable messages between a remote asset (10) and a central monitoring facility (15), the network communication system comprising: a data gathering module (16); an electronic storage device located at said remote asset to store said data (19); respective network interfaces (14, 18) located at said remote asset (10) and said monitoring facility (15); a processor to manage sending and receiving of said data (17); a packet switched network (25); a circuit switched network (40); and a plurality of communication states (21,22,23,24) interrelated with one another based on a predetermined communication protocol wherein said communication system transitions between said packet switched network (25) and said circuit switched network (40) depending upon which communication state of said communication states is in use. 2. The network communication system of claim 1 wherein said respective network interfaces (14, 18) located at said remote asset (10) comprise wireless, radio frequency transceivers allowing access to said packet and circuit switched networks (25, 40). 3. The network communication system of claim 1 wherein said predetermined communication protocol occupies an Application Layer (7) of said Open System Interconnection protocol model. 4. The network communication system of claim 1 wherein said plurality of communication states include an Asset Monitoring State (21), Polling State (23), Asset Diagnostic State (34), and Help State (22). 5. The network communication system of claim 4 wherein said Asset Monitoring State (21) allows for transmitting a message (30) at periodic intervals over said packet switched network (25) from said remote asset (10) to said central monitoring facility (15). 6. The network communication system of claim 4 wherein said Polling State (23) allows for transmitting a message (32) at specific intervals over said packet switched network (25) from said central monitoring facility (15) to said remote asset (10). 7. The network communication system of claim 4 wherein said Asset Diagnostic State (34) allows for transmitting bulk data (35, 37) and interactive terminal session data (38, 39) over said circuit switched network (40) between said central monitoring facility (15) and said remote asset (10). 8. The network communication system of claim 4 wherein said Help State (22) allows for transmitting a message over said packet switched network (25) from said remote asset (10) to said central monitoring facility (15) to request assistance. 9. The network communication system of claim 8 wherein said request assistance comprises data retrieval and remote diagnosis examinations. 10. The network communication system of claim 1 wherein use of said networks is a function of the relative cost of transmission of data over each said network. 11. The network communication system of claim 1 wherein use of said networks is a function of relative data transmission rates of data over each said network. 12. The network communication system of claim 1 wherein use of said networks is a function of relative quality of transmission over each said network. 13. A method for transferring computer-readable data between a remote asset (10) and a central monitoring facility (15), said method comprising: transmitting data in an Asset Monitoring State (21) over a packet switched network (25) from said remote asset (10) to said central monitoring facility (15); allowing said remote asset (10) to transition to a Help State (22) to request assistance; allowing said central monitoring facility (15) to transition said Help State (22) to acknowledge said request; transitioning from said Help State (22) to an Asset Diagnostic State (34); transitioning from said packet switched network (25) to a circuit switched network (40) in response to said transitioning to said Asset Diagnostic State (34); transmitting data between said remote asset (10) and said central monitoring facility (15) while in said Asset Diagnostic State (34); returning to said Asset Monitoring State (21) and to said packet switched network (25) when transmitting data during said Asset Diagnostic State (34) has ended. 14. The method of claim 13 wherein said transitioning from said Asset Monitoring State (21) to said Help State (22) further comprises commanding said remote asset (10) to modify its data collection configuration. 15. The method of claim 13 further comprising commanding said remote asset (10) while in said Asset Monitoring State (21) to modify its operational configuration such that said remote asset requests assistance in response to predetermined events. 16. The method of claim 13 further comprising commanding said remote asset (10) while in said Asset Monitoring State (21) to turn its communication equipment off and enter a dormant state for a determined duration. 17. The method of claim 13 wherein said Help State (22) includes said remote asset (10) sending a message to said central monitoring facility (15) requesting assistance in the form of data retrieval and diagnosis. 18. The method of claim 13 wherein said Asset Diagnostics State (34) includes transferring bulk data (35) from said remote asset (10) to said central monitoring facility (15). 19. The method of claim 18 wherein said bulk data (35) comprises measured data collected from data gathering modules located at said remote asset (10). 20. The method of claim 18 wherein said bulk data (35) further comprises geographic position of said remote asset (10) obtained via a position determining receiving electromagnetic signals system while in said Asset Monitoring State (21) 21. A method for transferring computer-readable data between a central monitoring facility (15) and a remote asset (10), the method comprising: commanding transferring of said data between said monitoring facility (15) and said remote asset (10) to occur in an Asset Monitoring State (21) over a packet switched network (25); commanding said monitoring facility (15) and said remote asset (10) to communicate in a Polling State (23); commanding said monitoring facility (15) to request data from said remote asset (10) while in said Polling State (23); acknowledging communicating in said Polling State (23); transitioning from said Polling State (23) to an Asset Diagnostic State (34); transitioning from said packet switched network (25) to a circuit switched channel (40) in response to said transitioning to said Asset Diagnostic State (34); transmitting data between said remote asset (10) and said central monitoring facility (15) while in said Asset Diagnostic State (34); and returning to said Asset Monitoring State (21) and to said packet switched network (25) when sending data during said Asset Diagnostic State (34) has ended. 22. The method of claim 21 further comprising allowing said monitoring facility (15) to direct said remote asset (10) to prepare to receive data from said central monitoring facility (15) while in said Polling State (23) . 23. The method of claim 21 further comprising allowing said central monitoring facility (15) to command said remote asset (10) to modify said remote asset's operating data collection configuration while in said Asset Monitoring State (21). 24. The method of claim 23 further comprising allowing said central monitoring facility (15) to command said remote asset (10) to turn its communication equipment off and enter a dormant state for a prescribed duration while in said Asset Monitoring State (21).

Inventors: DAVENPORT DAVID MICHAEL, DAVENPORT, DAVID, MICHAEL
Applicants: GEN ELECTRIC, GENERAL ELECTRIC COMPANY
Application year: 2000
Main classification: H04L12
IPC codes: B61L27, G08G1