FI113318B - Data communication procedure and data communication system - Google Patents

Description

113318

Field of the Invention

The present invention relates to a data transmission method for closed conditions, such as a mine, used in a data transmission system comprising one or more terminal devices and a network part comprising at least one base station, control station and backbone network in the communication system between the terminal and the base station. The station has a bidirectional connection to one or more implements via a terminal, each of which is connected to the implement.

The invention further relates to a communication system for use in closed conditions, such as a mine, wherein the communication system comprises one or more terminals and a network comprising at least one base station, a control station and a backbone network, the communication system having a radio link between the base station and the terminal. connection to one or more terminals connected to the implement.

Background of the Invention

Large-scale mining automation includes machines that operate automatically and / or remotely and are controlled and monitored either from the ground. 20 or underground control rooms. Automation allows additional; • · * * ;: reduce production costs, improve staff working environment. Telecommunication operations for heavy machinery and other communications in the mining environment require a telecommunications network to transfer: '; multimedia information between production areas and control stations.

* * ·· 25 Current state-of-the-art mining systems: T: are mainly analog. However, they provide insufficient performance, security and capacity for large scale automation applications. In a typical system, video, audio, and data are transmitted in an analog • • * ·. ··· format. in slow-channel channels. In addition, the signal '' '30 of each information source is modulated on its own carrier and the signals are distributed to the mine along a backbone coaxial cable which is radio-linked to the machines. Radio-

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the connection is provided either by antennas or the backbone network is partially or fully based; /. leaking cables. Such a solution is disclosed in Canadian Patent Application No. 2057544, Communication System, which is incorporated herein by reference. The backbone network is typically several kilometers long, whereby the transmitted signals have to be amplified at intervals to compensate for the attenuation of the cables, and since the amplifiers and other means of signal transmission are practically slightly nonlinear, the signals a lot of measurements and signal level tuning are required during installation. This in turn results in expensive network installation and poor adaptability.

Digital communication systems provide better connectivity than analog systems. But the typical problem with these systems is that their data transfer is not real-time. For example, in systems based on a LAN architecture, LAN protocols cannot guarantee that the information to be transmitted is always transmitted at the same rate from sender to receiver, or that data is transmitted even within a predetermined time. The typical transmission delay of a typical prior art digital communication system is too large and variable for real-time telecom operations. Indeed, the use of digital systems, especially in mines, has been limited to non-real-time, non-critical applications.

Brief Description of the Invention

It is an object of the invention to provide a method and apparatus according to the method so that the above problems can be solved. The solution according to the invention can implement real-time multimedia information; transfer from the mine shaft to the control station.

. This is achieved by a method of the kind described in the introduction, characterized in that one or more work machines are controlled from a control room -> * · position in a substantially real-time manner using a deterministic: 25 communication protocols whose determinism is based on "radio interface, network interface and 1 / 0- '' by layer packet data, input and output data routing, and hard initialization and control, and wherein the data transmission delay is within a predetermined range of ;;

; The communication system according to the invention, in its turn, is characterized in that the communication system comprises a deterministic communication protocol, the determinism of which is based on the physical layer packetization of the radio interface, the network interface and the data input / output ports in the I / O layer. and output data routing and hard ·: i 35 initialization and control, and the communication protocol allows one or more of the 3,333,188 working machines to be controlled teleoperatively in substantially real-time, with communication delay within predetermined limits.

The method and system of the invention provide several advantages. The information intended for the user is transmitted within the system with a predetermined delay regardless of the load on the system. Interference is less, base stations have a wider coverage range, and system installation and flexibility is better than prior art solutions. Also, the video signal quality is better and the number of connections is higher than the known solutions. In addition, security in a digital system is better than 10 in an analog system. Telecom operations require real-time system performance, which is not sufficiently well-known by prior art digital and teleoperative multimedia systems with multiple simultaneous users.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be further described in connection with preferred embodiments, with reference to the accompanying drawings, in which:

Figure 1 shows a communication system;

Figure 2 shows a packet used for data transmission;

Figure 3 illustrates a work machine connected to a communication system; Figure 4 shows the control station and

Figure 5 shows a protocol stack.

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DETAILED DESCRIPTION OF THE INVENTION: The solution of the invention is suitable for use, in particular, but not limited to mining. Other applications of the invention include, for example, tunnels, buildings, open-cast quarries and safety critical areas (nuclear power plant, mine clearance). The basic idea of the invention is to provide transparent point-to-point data links between terminals and control panels: ·. Control stations and terminals provide an interface for connecting peripherals, such as remote controls, computers, cameras, and other devices.

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Digital broadband technology according to the invention; · The data transmission system is well suited for telecom operations and monitoring of heavy mining machinery. Let us now examine the solution of the invention in more detail by means of the example in FIG. The system comprises at least 35 one control station 10-12, a network connection 13, a switching means 14, a main gateway 11, a second network connection 16 and base stations 17 in the network section 20. The network connection 13, the switching means 14 and the main cable 15 form the core network. The core network according to the invention may at least comprise a main cable 15 between the control station 10-12 and the base station 17, which may also be replaced by a radio link. Thus, the network part 20 comprises only the control station 10-12, the backbone network (main cable 15 or radio connection) and the base station 17. The data transmission between the control station 10-12 and the machine 19 according to the invention is digital. The communication system also includes a deterministic communication protocol by means of which one or more work machines 19 from the control station 10 -12 can be teleoperatively controlled in substantially real time, since the communication delay remains within predetermined limits by the communication protocol regardless of load. Real-time refers to the on-going process. The maximum transmission delay in the solution according to the invention is preferably less than 10 ms.

The network portion 20, which is backboneed by a backbone network of cables 13, 15 and 16 and switches 14, preferably operates on a multicasting principle, where the transmitted messages are forwarded to more than one network-connected unit 20. Thus, for example, the message transmitted from the control station 10 proceeds initially to the switch 14 which transmits it to the control stations 11 and 12 and further to the main cable 15 from which the message propagates to all units 14, 17, 18 and 19. Instead of sending messages to all units, the number of recipients of the messages may also be limited. In this case, for example, the control station 12 may only be in dual-side multicasting to the right-hand terminals .. * * 18 and the work machines 19. In this case, the control station 12 and the right-hand terminals 18 and the work machines 19 advantageously cannot see any other system. In a similar way, by limiting multicasting connections to the core network, other devices (e.g., terminals, sensors, etc.) that are not visible in the system can be connected. I: '30 even though they use it.

The network part 20 is preferably an ATM network (Asynchronous Transfer, *,: Mode) or the like. An ATM network typically provides a data rate of 155 Mbps. For example, one connection between machine 19 and control station 10-12 requires a data rate of about 1 Mbps, so that the ATM trunk • 35 network allows simultaneous monitoring and control of at least several tens of machine 19 from each control station 10-12.

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In a preferred embodiment of the invention, the ATM backbone network operates on a multicasting basis such that the ATM Routing Switches 14 operate independently without separate control. In this case, the switches 14 direct the incoming message to all units belonging to the communication system. This differs somewhat from the normal operation of ATM network switches. ATM switches are programmed such that packets received from one port are transmitted as such without changing address and data fields to all other ports. The Multicas-Ting principle simplifies the system, since very heavy signaling, which is currently incomplete, for example in an ATM network, is not required.

10 Instead of autonomous operation, the ATM core network may operate on a multicast Ting principle such that the ATM switches 14 are centrally controllable. The switches 14 are preferably controlled by signaling from control stations 10-12.

In this case, the switches 14 direct the messages to the different units as desired. This can reduce unnecessary data transfers. For example, the monitoring station 10 may initially start multicasting only with the right units of FIG. and later only to the lower units of Figure 1. In this case, this arrangement will not | visible to the rest of the system and not visible to other parts of the system. The switches 14 are preferably FSR (Frame Synchronous Ring) switches. The prior art FSR switch is based on a ring topology and is simple and efficient. The FSR switch is suitable for broadband switch applications. FSR switches suitable for the ATM interface also allow, for example, the use of optical fiber at 155 Mbps (SDH / STM-1) and 100 Mbps (TAXI) and; ; using a metal wire at 34 Mbps (PDH / E3) and 2 Mbps (PDH / E1).

. · ·. The communication system according to the invention establishes a connection between the terminal 25 and the base station, preferably via a wireless spread spectrum signal. ; Although connection can be established even without spread spectrum technology. In spread spectrum technology, a user narrowband data signal is modulated to a wider bandwidth required by the data signal. In prior art solutions, in which the signal of each transmitter is modulated to its own carrier 30, the terminal amplifier of the control station 10-12 and any intermediate amplifiers in the network:, .. have to process the multi-carrier signal. This causes a problem of intermodulation. The power of each carrier • · ..... must be kept quite low to reduce intermodulation, which results in a short range of signals. The scattering and reflection of the radio signal in the mine causes multipath propagation and fading, leading to: ·: Often major problems in prior art solutions. In the solution of the invention, the intermodulation problem is eliminated because the video, data and audio signals are digitized and multiplexed into a common bit stream already by the terminal, whereby only one carrier per terminal is required. Since there is no problem of intermodulation, higher transmission powers can be used, thereby extending the signal range. Because of the longer range, cabling and antennas no longer need to be installed in the latest production areas. In turn, due to spread spectrum technology, the effect of multipath propagation is reduced. In addition, in the network part, the data transmission is carried out digitally in baseband, whereby no intermodulation occurs.

The communication system is adapted to carry out communication over a wide bandwidth, whereby the communication system comprises a plurality of multimedia channels, so that the system enables a virtually unlimited number of connections between the mining shaft / terminal and the ground / control station. Broadband thus allows, in addition to audio and speech signals 15, to simultaneously transmit and receive video data and control signals, both in the mine shaft and on the ground. Thus, the communication system transmits one or more of the following types of data substantially simultaneously: image, audio, data. Based on the image information, it is possible to control the work of the machine 19, to direct the machine 19 from one tunnel to another at the workstation 20, etc. The audio information may include engine sounds, for example, control room 10-12 to hear if the engine is OK. also human speech from control room to 10-12 mine or mine: control room 10-12. The data and control signals monitor, for example, work. their condition by means of sensors on the machinery and the control of the machinery 19.

. ·. The communication system preferably transmits the image, voice and data in packets, which are preferably ATM cells or the like. The packets are transmitted • »*" ... unchanged over the radio interface. Base station 17 and terminal 18 may be in radio communication with each other in FDMA (Frequency Division Multiple Access), TDMA (Time Division Multiple Access), SDMA (Space Division Multiple Access). : 30 cess) or CDMA (Code Division Multiple Access) technology, or CSMA / CD (Carrier Sense Multiple Access with Collision Detection) technology ...: can be used, but it must be ensured that the operating system is sufficient · Fast for real-time data collision, for example, using bandwidths of 1 to 50 MHz FDMA technology: 35 users are separated by frequency band, TDMA technology sends users in different time slots, SDMA technology sends signals to 7 113318 recipients and CDMA technology separates users based on a spreading code.

Each terminal has a fixed communication bandwidth, which bandwidth is allocated by the communication system to image, audio and data. With lots of data and control signals, there is less data transfer capacity for picture and sound. In the inventive solution, in a data transmission system, image and sound are compressed digitally to allow for more efficient data transmission. By means of compression, the bandwidth needed to transmit the video signal can be reduced up to 50 times smaller than the uncompressed video signal 10 without loss of image quality. The data and control signals are not compressed in the inventive solution. In the solution of the invention any prior art image compression method is possible. Advantageously, in a communication system, the image is dynamically compressed, which means that if the data transmission requirement exceeds the available capacity, the video signal is compressed more and more until the required data transmission demand of the video signal corresponds to the available amount. This ensures the adequacy of the communication band in all situations and delays of deterministic transmission of information of the highest priority, such as control data. The transfer capacity is not unnecessarily reserved for any information, although the amount of data to be transmitted varies. Thus, in the compression, the properties of the image, i.e. the information content, are reduced, if necessary, so that its information always fits in the remaining transmission bandwidth. This keeps the image quality at par-:: level.

In the inventive solution, image compression is used. For example, 25 digital video matched median filtering of a video image, wherein a reference value is generated for the pixel block to be processed. The value of each pixel in the pixel block * t · is compared to a reference value, and if the value of the pixel deviates from the reference value by more than a threshold value, the pixel value is replaced by a reference value. In dynamic compression, the magnitude of the threshold can advantageously be adapted to the available data throughput / bandwidth.

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For packet transmission, fixed bandwidth means si-, ··. that each terminal transmits a fixed number of packets in a unit of time to which image, audio and data must be placed. Thus, when compressed, the actual information content of the image information V 35 is reduced, if necessary, so that its information always fits into the remaining space of data and voice in each packet. The communication protocol used in the present invention is also optimized for transmitting information over the radio / backbone interface. In this case, the packet data representation of the data remains unchanged throughout the communication system.

The packet shown in FIG. 2 is similar to an ATM cell and comprises an MT / ID part 21, which is a machine identifier, and a data part 22. The packet comprises a total of 48 bytes. The data is divided into N fields, each having a preamble 23 and a data part 24. Each preamble indicates the tube number 25 and the data length in bytes 26. One byte typically comprises 8 bits. The packet contains 7 different pipe data as well as the system-wide 10 control data transmitted in pipe 0.

The communication system establishes logical connections between the units by means of a graphical user interface. A logical connection means that a physical connection, such as a wire, changes over time, but the connection or communication itself does not change and is not disturbed by changes in the physical connection. The stylish-15 graphical user interfaces include Windows and X-windows. The graphical user interface provides users with clear information about networked units, communication interruptions and hardware failures, and allows for flexible logical connections between units.

Remote controls, computers, cameras and other devices are connected to 20 inventive communication systems, for example, using the following interfaces 13 and 16: RS-232, RS-485, Profibus and Ethernet LAN.

: A: Figure 3 shows a working machine. The work machine comprises a terminal 18,: the actual machine 19, a camera 31, a microphone 32, a loudspeaker 33, and a sensor 34. The camera 19 is preferably rotatable in different directions: vertical and horizontal. Camera 19 can be any black and white or color camera. The microphone 32 and loudspeaker 33 of the terminal 18 allow bidirectional * ► * ... audio transmission. The sensor 34 measures something important for the operation of the machine 19, for example temperature, and signals the information to the monitoring station 10-12, at least in the event of a disturbance.

Figure 30 shows a control station. Control station 10-12> I · ...: associated with a monitor 41, which displays an image transmitted by the camera 31 and graphical user interface information on the system status, and machine control means 42, · * ·. The control station 10-12 also includes a microphone 43 and a loudspeaker 44 to enable audio transmission.

»*. Let us now examine the deterministic communication protocol of the invention using the Open Systems Interconnection (OSI) model. The de-113318 g terminism, which means a predetermined communication delay regardless of load, is preferably applied only to real-time user information, but not to system-wide signaling. Typically, video image compression takes from 120 ms to 150 ms, leaving a few tens to 5 milliseconds of data transmission, while aiming at a total delay of 150 ms to 200 ms, which allows for real-time remote control. Figure 5 shows a protocol stack comprising a physical layer 51, an I / O layer 52, a Medium Access Control layer 53, an I / O routing layer 54, and a control layer 55. Above these is the application layer 56. The physical layer 51 provides a 10 aa radio interface, an ATM interface and data input and output ports. The I / O layer 52 provides data packing, input and output data routing between pipes 0 ... 7, and hard initialization and control. MAC layer 53 provides connection establishment, automatic network neighbors identification, control data transfer in pipe 0, error checking, retransmission, etc. The term pipe refers to virtual pipes formed between units between different input and output ports. The control layer 55 provides communication between system units, automatic identification of system units, and control data transmission and reception units (via MAC). Internal control data (pipe 0) of the system 20 is routed within units by MAC layer 53 and further, if necessary, by control layer 55.

: A: The deterministic nature of the protocol is based on five properties. All: user data such as remote control commands, image information, or audio in-; y; the information is packaged and routed directly by the I / O routing layer to the desired interface (e.g., the radio interface). The terminal or control station transmits the packet at predetermined intervals, for example 0.4 ms, and all data coming from I / O (tubes 1 ... 7) after the previous packet is taken into the packet. The base station routes the packet received from the terminal via the radio interface directly on the I / O routing layer 54 to the ATM interface towards the control station. Package counter-. : 30 returning control station or terminal decrypts the packet and routes the user data directly to the desired I / O port on I / O routing layer 54 (pipes 1 ... 7). User error data transfer ... does not use error detection methods or re-send, · * ·. tyksiä. However, it is possible to arrange debugging and retransmission on the remote control station and the machine to be controlled. Deterministic! 35 The ministry is also facilitated by the fact that the network part functions as a cheaply connected · · “11331” network like ATM, where no data collisions occur. The network component has a very high capacity and the switches are non-blocking.

The I / O layer 52 forms pipes between the devices of the communication system, which are always connected to a physical input or star port. Port 5 may be a serial port, a video unit, or other communication system device. Based on the control information from the upper layers, the I / O layer 52 knows the recipient of the data from the different tubes, whereby the information can be transmitted immediately without being circulated through the upper layers. Since the terminal and the monitoring station send the packet at regular intervals, the data accumulated since the previous packet is collected in all 10 L / O ports. The packet is transferred back to the physical layer either at the radio interface or the ATM interface. At the radio interface, a byte-length preamble is added in front of the packet, which is required at the receiver to identify and synchronize the packet. In the ATM interface, a 5-byte field is inserted in front of the packet, which contains the connection identifier 15 and additional information about the connection mode. The identifiers added by the physical layer do not appear on the I / O layer 52. The base station receives packets from the ATM network and routes data from different pipes in a predetermined manner. Control data (pipe 0) is transferred to the upper layers and user data (pipes 1 ... 7) is directly transmitted from the I / O layer 52 to the physical layer at the radio interface. Thus, the establishment of the connections, the setting of the I / O layer 52 and the control of the system are handled by the upper layers. The principle is that the control layer knows the size: Y: size of the transmission system, the MAC layer knows the neighboring nodes, and the I / O layer 52 knows: the routing of data passing through different pipes. The user data is transmitted all the time with up to an I / O layer 52, which guarantees the determinist according to the invention. : 25 of its knowledge transfer.

While the invention has been described above with reference to the example of the accompanying drawings, it is understood that the invention is not limited thereto but that it can be modified in many ways within the scope of the inventive idea set forth in the appended claims.

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Claims (26)

A data transmission method for closed conditions, such as a mine, used in a data transmission system comprising one or more terminal devices (18) and a network part (20) comprising at least one base station (17), a control station (10-12) and a backbone network. (15) having a radio link in the communication system between the terminal (18) and the base station (17) and bidirectional communication from the control station (10-12) to one or more work machines (19) via a terminal (18) each connected to the work machine (19); the communication between the control station (10-12) and the terminal (18) 10 is performed digitally using a layer-based communication protocol (51-56), characterized in that one or more work machines (19) are teleoperatively controlled from the control station (10-12) substantially in real time using a deterministic communication protocol , whose determinism is based on the physical layer (51) radior access to the time interface, the network interface, and the data input and output ports 15 via data packetization, input and output data routing and hard initialization and control on the I / O layer, and wherein the communication delay is within predetermined limits. Method according to Claim 1, characterized in that the network part (20) operates on a multicasting principle, in which the transmitted messages are forwarded to more than one unit connected to the network. • i f • · Method according to claim 1, characterized in that: Y: that the data transmission is carried out in a network part (20) such as an ATM network. A method according to claim 3, characterized in that the ATM network part (20) operates on a multicasting basis, such that the ATM switches (14) operate independently without control. A method according to claim 3, characterized in that the ATM network part (20) operates on a multicasting basis, with the ATM switches (14) being centrally controlled. »· A method according to claim 1, characterized in that the transmitted messages are forwarded to all units connected to the network. * · * · * »· 113318 Method according to claim 1, characterized in that the connection between the terminal (18) and the base station (17) is established by wireless spread spectrum signaling. A method according to claim 1, characterized in that the data transmission is carried out broadband, and the data transmission is carried out substantially simultaneously with one or more of the following data types: image, audio, data. 9. A method according to claim 8, characterized in that the data, data and data are transmitted in packets. A method according to claim 8, characterized in that each terminal (18) has a fixed communication band, which band in the communication is allocated to image, audio and data. The method according to claim 8, characterized in that the image and / or the sound are compressed for data transmission. 11 113318 A method according to claim 11, characterized in that the image is compressed dynamically. 13. A method according to claim 1, characterized in that logical connections are established between the units by means of a graphical user interface. • · • »» 14. Communication system for use in closed conditions, such as a mine, wherein the communication system comprises one or more terminal devices (18) and a network part (20) comprising at least one base station (17), t * I v: a monitoring station (10 -12) and a backbone network (15) having a radio link between the base station (17) and the terminal (18) in the communication system and the control station (1 to 25) having a bidirectional connection to one or more terminals: ': ( 18) which are connected to the implement (19) and the communication system is adapted • · · *. perform data transmission between the monitoring station (10-12) and the terminal (18) digitally using a data transmission protocol based on the layers (51-56), characterized in that the data transmission system comprises a deterministic data system. a donation protocol based on physical layer ·; ··· (51) radio interface, network interface and data input and output ports for I / O layer (52) data packing, input and output data routing, and hard initialization and control and, by means of a communication protocol, one or more work machines (19) can be teleoperatively controlled in substantially real time, with a communication delay within predetermined limits. A communication system according to claim 14, characterized in that the network part (20) is adapted to operate on a multicasting principle, in which the transmitted messages are transmitted to substantially all units connected to the network. Communication system according to claim 14, characterized in that the network part (20) is essentially an ATM network. Communication system according to Claim 16, characterized in that the ATM network part (20) is arranged to operate on a multicasting basis, such that the ATM switches (14) operate independently without separate control. Communication system according to claim 16, characterized in that the ATM network part (20) is arranged to operate on a multicasting basis, such that the ATM switches (14) are centrally controllable. The communication system according to claim 14, characterized in that the communication system is adapted to relay the transmitted I »'· ·' messages to one or more units connected to the network. > · ·; Y; 20 The communication system of claim 14, characterized by: -. characterized in that the communication system is adapted to establish a connection between the terminal device (18) and the base station (17) by wireless spread spectrum signaling. • · The communication system according to claim 14, characterized in that the communication system is adapted to perform broadband communication and the communication system is adapted to transmit one or more of the following types of data at the same time «IMI»: picture, sound, data. »·; .Y The data transmission system of claim 21, characterized in that the data transmission system is adapted to transmit t · (I »image, audio and data in packets. Communication system according to claim 21, characterized in that each terminal has a fixed communication band, the bandwidth of which the communication system is adapted to allocate for transmission of image, sound and data. Communication system according to claim 21, characterized in that the communication system is adapted to compress image and / or audio for communication. Communication system according to claim 24, characterized in that the communication system is adapted to dynamically compress the image 10. Communication system according to claim 14, characterized in that the communication system is arranged to establish logical connections between the units by means of a graphical user interface. * 1 · • 1 • # · • · I »I • · <· · * 1 · * t · *» »·» · III1 · • I · »„ 113318