WO1994018578A1

WO1994018578A1 - Method and device for positioning, communication and flow control

Info

Publication number: WO1994018578A1
Application number: PCT/SE1994/000084
Authority: WO
Inventors: Mikael TIMSÄTER; Leif MOSTRÖM; Jonas RÖNNKVIST
Original assignee: Lmt Data Hb
Priority date: 1993-02-09
Filing date: 1994-02-03
Publication date: 1994-08-18
Also published as: SE9300449D0; AU6047694A; SE500976C2; SE9300449L

Abstract

Method and device for positioning in a system, for example through data exchange for use in projection works, flow control or the like, including: a number of mobile units (2); at least one central unit (9); a number of transmitter and/or receiver stations, so called mobile nodes (7) and reference nodes (5, 6, 7), arranged inside and/or outside a volume (4), such as an opencast mine (15), a local transportation system or the like. Information exchange between the mobile units and the reference nodes (5, 6) and signal detection is performed by means of an information carrying medium, such as electromagnetic carrier waves or the like. In the central unit (9) and/or the mobile unit (2), the positions of the mobile units are generated in a number of coordinates, preferably three (X, Y, Z), by the distances to the reference nodes (5, 6) being measured, compiled and the position being calculated. The reference nodes (5, 6) which are stationary but movable, are placed inside and/or outside the volume (4), so that at least three reference nodes (5, 6) are detectable from each mobile node (7) at each point within the volume. The reference nodes are placed in such a way that a scalar (CGU) at each point within the volume (4) is kept within a minimum and maximum value (O«CGU«CGUmax).

Description

METHOD AND DEVICE FOR POSITIONING, COMMUNICATION

AND FLOW CONTROL.

The present invention refers to a method and a device for positioning in a system, eg. through data exchange for use in planning, flow control or the like, including:

- a number of mobile units;

- at least one central unit;

- a number of transmitter stations and transponder stations, so- called mobile nodes and reference nodes, provided inside and/or outside a volume, such as an opencast mine, a local transportation system or the like, whereby information exchange between the mobile units and the reference nodes, and signal detection is performed by means of an information carrying medium, such as electromagnetic carrier waves or the like.

Background of the invention

In later years the satellite based positioning system GPS (Global Positioning System) has received more prominent roles within most of the navigation areas. GPS is a worldwide positioning system, which offers the user possibility to determine its position in real time with a precision in order of some metres. The list of applications where the GPS-system is used now already can be made very long. GPS, for instance is used for boat, car and aviation navigation. Within the trade and industry frequently the GPS-positioning is completed by mobile units with some form of feedback coupling to a control centre. This makes it possible to optimize and control, e.g. the transportation flows. Properly used, this can give substantial rationalization effects. However, it is indicated that there are environments and utilization areas where the GPS does not function. Examples of these environments are places where the satellite signals are shielded, for example by high-rise buildings, mountains and vegetation and/or where better exactness in position declarations are required. In certain fields of application, this problem is possible to circumvent, for instance by means of slack calculation, i.e. positioning when the GPS-system can not be reached, gyro technic etc. Within other fields of application one must find new solutions.

For example in opencast mines positioning of the machines working in the mine is desired with an accuracy higher than half a meter in all coordinate axes directions. The environment is exacting and the rock faces efficiently shield the signals of the GPS satellites.

Today, the planing procedures like production control in opencast mines is done partially and by means of schedules drawn up in advance. The communication in the mine is performed primarilly by means of communication radio. The computerization in the mining itself is low, like the degree of integration between the different planing and follow-up systems. The management of the total flow planning-drilling-sampling-blasting-loading-transport-storing- enrichment-transport-melting is today performed only to a limited extent and mainly in batches and with manual routines. Prerequisites for controlling a movable and outdoors located production process is a well-integrated information flow between all units, ie. planing office, operation control, drills, blasting, excavators, trucks, enrichment unit, and so on, and perhaps most important of all, knowledge of where the different units are and which type of ore, with which for example the excavators and the trucks work, so that no granite is transferred to the enrichment and no rich ore is transferred to the tip.

A number of positioning methods are known, for example by US-A- 4,831,539, a system for identification of the position of a vehicle, collection of vehicle data and coexecuting of collected data with the position of the vehicle. Through comparison of data and position, a database containing information for guiding the vehicle performance, reporting deviations in performance and generation of control signals for commanding the vehicle movements, are generated. The system includes a number of signposts, provided at fixed distances from the vehicle, whereby each signport is identified by an identity, which is characteristically associated witn each destination.

In each vehicle a device is arranged for detection of a signport, when the vehicle is within a predetermined distance from a signpost. The device generates data indicating the position of the vehicle as a result of the detection of a signpost. In each vehicle is also provided sensors for collection and storing of data about the performance of the vehicles. The position and performance data are run together to provide a database, by means of which a computer can manage the performance, report deviations, locate the vehicle and control the vehicle's movements.

Drawbacks with above described system are stationary installation of each signport, one signport in near connection to each point wanted to be positioned, which reduces the flexibility, and results in discrete positioning, poor precision and positioning two dimensions only.

US-A-5,119,104 describes a radio positioning system, including mobile units with identity transmitters (TAG transmitters), a number of receiver groups connected to a central unit via a network. Each mobile unit transmits a TAG-package, containing a unique identity, which package is received by a group of receivers. Besides the mobile TAG-transponders a number of stationary TAG-transmitters with known position (the distance to each receiver) are provided, which are used for the calibration of the system.

Each receiver in the receiver group, receives and sets the receiving time TOA (time of arrival), and transfers this time to the central unit. The central unit calculates the positions. This system is used for positioning in two dimensions. Position determination is executed in the central unit, which makes the whole system dependant of the central unit, stationary installation of the TAG-transmitters (reference transmitter) are required, and all receivers must be connected via the computer network to the central unit. Through the international patent application WO 92/05672 a method is known for localization of mobile radio stations, particularly the existing system GSM. The system consists of mobile stations and base stations. Each mobile station continuously listens to the base stations in a number of control channels. The mobile station chooses at least three base stations, which are requested by the mobile station. Each base station calculates the distance to the mobile station. The calculated distance and identity information about the mobile station is sent to a localization unit, which calculates the position of the mobile station.

Also this system suffers from poor precision (magnitude of several 100 m) and has no possibility of positioning in three dimensions. Further, the method requires access to the mobile radio system (GSM) in the area where the positioning procedures are desired. The object of the invention and its characteristics

The main object of the invention is to provide positioning in three dimensions with superior precision and cost efficiency. Another object of the system according to the present invention is that the positioning of the mobile machines, vehicles etc., is facilitated appreciably simultaneously as the positioning accuracy increases up to 10 cm.

In an opencast mine the planing and the management works can, for example be integrated with dressing plant and with the machines working in the mine. Machines, office and dressing plant are connected. The outmost consequence of the invention is that the production process changes from having been batch controlled to almost being real time controlled. The invention means that the mining in opencast mine can increase the capacity highly and presents advantages, such as increased winning in the enrichment process, reduction of impurities in the metal procduced, cost reductions at drilling, blasting, loading procedures, cost reductions the transportation flows and administration as well as improved working conditions.

Range-finding using microwave technology gives a number of very important advantages, such as insensibility to the hard environment conditions, no movable parts, high precision, low power consumption, simultaneous data transmission, quick range-finding as well as a well-tested technology.

The invention can also be used for data exchange and positioning between aircraft and/or a central unit. By pilotage and port making of boats a pilot on each boat is required, which through positioning by means of this invention can be simplified, so that pilot support is given from shore to several boats at the same time. Further, the system according to the invention can also be used for controlling the transport flow and production processes in ports, airports, at building and construction sites as well as at platforms at sea.

These tasks have been solved by generating the position of the mobile unit in the central unit and/or the mobile unit in a number of, preferably three, coordinates, by measuring the distances to the reference nodes, whereby the data are compiled and the positions are calculated, and that the reference nodes, stationary but movable, are placed inside and/or outside the volume, so that at least three reference nodes exist detectably from each mobile node at each point within the volume, and that the reference nodes are situated so that a scalar at each point within the volume is kept within a minimum and maximum value. Description of the drawings and terminology

In the following, the invention will be explained further with reference to the following terminology, fundamental for the system description and also the attached drawings, on which:

Fig. 1 discloses a survey drawing of the basic system parts.

Fig. 2 shows a three-dimensional drawing of an opencast mine and a practical application of the invention.

Fig. 3 discloses a generalized three-dimensional image of a theoretical system volume. Fig. 4 shows a basic model of a microwave based equipment for distance measurement.

Fig. 5 discloses the grounds for message handling in a system according to the invention.

Fig. 6 shows the fundamental construction design of the message package.

Fig. 7 shows the basic system structure for message path selection.

Fig. 8 discloses the basic course of events at data communication in the system according to the invention.

Fig. 9a, 9b and 9c show the basic structural design of a mobile unit of the system.

Fig. 10 shows the basic structural design of the system at a central unit and connected user. Fig. 11 shows a basic flow chart of a communication programme of a mobile computer. Fig. 12 discloses a fundamental flow chart of a positioning programme of a mobile computer.

Fig. 13 shows a basic flow chart of a communication programme of each input channel for administration of the message flow in a central unit.

Fig. 14 shows a drilling machine in an outlined opencast mine. Fig 15. discloses an example of a screen layout showing a display unit connected to a mobile computer.

Terminology; Application

An application (fig. 1) is the denomination of the location, where the system 1 is used, for example in an opencast mine (fig. 2) or a dockyard. Mobile unit 2

The final mobile user (fig. 1) such as a machine, vehicle and/or man using the system functions inside or outside the system volume.

User 3

Immobile final user (fig. 1) such as a machine and/or man using the system functions outside the system volume.

System volume 4

The volume (fig. 1,3), within which the mobile units 2 can use the system functions.

Data reference node 5

Active microwave reflector for distance measurement between the data reference node 5 and the mobile node 7. Equipped with data transmission function for data transmission between the mobile node and the data reference node at the same time as the distance measurement is performed. Each data reference node 5 is stationary but movably installed inside or outside the system volume 4 at the position (XR_n,YR_n,ZR_n) , n=1, 2, 3 .. n_max, where n_max is the total number of reference nodes 5 or 6. Each data reference node has a unique identity number n. The data reference node 5 is further connected to wired short distance broadcast modem/radio modem/network/optical fibre/other solutions for data communication with the central unit. Reference node 6

Active microwave reflector (fig. 1, 4) for distance measurement between reference node and mobile node 7. Firmly but movably installed inside or outside the system volume 4 at the position (XR_n,YR_n,ZR_n), n=1, 2, 3... n_max, where n_max is the total number of the reference nodes 5 or 6. Each reference node 6 has a unique identification number, n.

Mobile node 7

Microwave based distance measurement device (fig. 1, 4) for determination of the distance between mobile node and reference nodes. The mobile node 7 also facilitates data transmission (fig. 8) to the data reference nodes, simultaneously as the distance measurement is performed. The mobile node is placed at the mobile unit 2, e.g. on a machine or vehicle. The mobile node is exactly at the position (X^* _1m, X_*2m, X^* _3m) while the position calculated by the system is designated by (X_1m, X_2m, X_3m), where m = 1, 2, 3 .. m_Max, m_Max is the total number of the mobile nodes in the system. Each mobile node has a unique identification number, m. Mobile computer 8

Computer unit (fig. 1, 9), which is provided in close connection to the mobile node 7, e.g. on a machine or vehicle. The mobile computer is connected to a mobile node, and also a possible display unit, keyboard, printer, electronic compass, control and adjustment equipment for the machine or the vehicle and/or other peripheral equipment specific for the application. The mobile computer administrates the package mediating message flow (fig. 8) to and from the central unit 9, maintains a local database, calculates the position of the mobile node, and executes the application specific software.

Central unit 9

Central computer unit (fig. 1, 10) located at some kind of management centre, supervision centre, control centre or communication centre. The central unit consist of the system interface towards the users and those software specific for the application. To the central unit are connected: all data reference nodes 5 included in the system as well as via conventional computer network 11 or other conventional communication devices to the users 3. The central unit, for instance administrates the message flow (fig. 8) between the user and the mobile unit 2 and monitors the positioning functions of the system.

System operator 10

Person responsible for maintenance and attendance of the system 1.

Computer unit 12

The computer unit (fig. 1) which serves the users. The computer unit is connected to the central unit 9 via conventional computer network 11 and thereby has access to the administrator database 79 included in the central unit, and also the data communication functions of the system for the user messages.

Description of embodiment Fig. 1 discloses schematically the system configuration according to the invention. The system 1 consists of:

- a number of mobile units 2, on which are provided at least a mobile node 7 and a mobile computer 8,

- a number of stationary but movable reference nodes 5 and 6, some of which are provided as data receiver/transmitter, so-called data reference nodes 5, - which are connected via a network, radio relay station or the like to at least a central unit 9 in form of a computer or the like,

- which in turn, via a network 11 can be connected to a number of computer units 12, for transfer of information and data to and from a number of users 3. The central unit can be monitored by a system operator 10. The three-dimensional image of an opencast mine 15, shown In fig. 2, shows an example of positioning of the reference nodes 5 and 6, some of which are always detectable from the mobile node 7. Two-way data communication is possible between the mobile units 2 and, for example a control centre 13 or the like. The data communication is performed via the data reference nodes 5.

In fig. 3 a theoretical system volume 4 is shown, i.e. an area with X, Y and Z coordinates. Such a system volume can be referred to a production place, an opencast mine and so on. By placing reflectors (nodes) so that one or some nodes always have a certain difference in altitude to the mobile units, which should be positioned and by using microwave technology for distance measurement, a possibility of three- dimensional positioning is obtained.

The system decides the position of each mobile node 7 with certain time interval (dt_m) by measuring by microwave technology the distance between the mobile node 7 and all reference nodes 5 and 6, which are detectable therefor. The time interval can be varied between different and/or individual mobile nodes, depending on how frequent updating of the position indication is required. The most accurate procedure at present at microwave based distance measurement, according to fig. 4, is based on the principle that the mobile node 7 transmits a modulated carrier wave 16, which is received by the reference node 5 and 6, which in turα synchronizes its internal oscillator clock, code measurement device or the like with the received signal and retransmits the synchronized signal 17 to the mobile node. The mobile node 7 receives the retransmitted signal and compares the phase difference or the delay between the transmitted and the received signal. The distance 18 between the mobile node and the reference node can now be determined, since the distribution speed of the microwave is known. To distinctly determine the distance, however it is required that the above described procedure is executed in a number of different modulation frequencies. Since the equipment works in the microwave area, detection possibility is required between the mobile node and the reference node for reliable function.

At present there are microwave based distance measurement components, which at the same time can determine the distance to six reference nodes with a precision of +/- 10 cm for distances between 20 m to 50 km in less than a second. The components also permit, at the same time as the distance measurement is executed, data transmission between the mobile node 7 and the data reference node 5, for example using the serial protocol RS232 with data transmission rate of up to 9600 Baud.

The reference nodes 5 and 6 are situated inside and/or outside the system volume 4 in such a way (fig. 3) that at least three reference nodes 5 and/or 6, thereof at least one data reference node 5 is detectable by each mobile node 7 at each point within the system volume. Further the reference nodes should be placed in such a way and be measured, for example through conventional surveying methods, such as geodimeteri, with centimetre precision, so that a scalar, called CGU (Contribution of Geometrical Uncertainty (equation 6)) at each point within the system volume, is kept within an interval. This, for keeping the precision of the position indications required by the application precision. The distances measured by the mobile node to all detectable reference nodes are compiled in the mobile computer 8 and stored, according to fig. 9c in a matrix D_m 66 in the so- called mobile system database 31. The matrix D_m contains the results of the distance measurements, which are decided by the system, as well as the identification numbers n of the reference nodes 5 or 6. In the mobile system database 31 the reference node data in the matrix REF_m 65 have been stored in advance. The matrix contains information about all reference nodes placed inside and/or outside the system volume. The information includes positions (XR_n, YR_n, ZR_n) of the reference nodes, identity number n as well as the type, i.e. reference node 6 or data reference node 5.

The relationship between the position (X_1m, X_2m, X_3m), D_m and REF_m of the mobile units gives the following unlinear and generally over defined compound equation f_1m=(X_1m,X_2m, X_3m)=(XR₁-X_1m) ²+(YR₁-X_2m) ²+(ZR₁-X_3m)²-(D_1m) ²=0 f_2m=(X_1m,X_2m, X_3m)=(XR₂-X_1m) ²+(YR₂-X_2m) ²+(ZR₂-X_3m)²-(D_2m) ²=0 f_3m=(X_1m,X_2m, X_3m)=(XR₃-X_1m) ²+(YR₃-X_2m) ²+(ZR₃-X_3m)²-(D_3m) ²=0 f_nm=(X_1m,X_2m, X_3m)=(XR_n-X_1m) ²+(YR_n-X_2m) ²+(ZR_n-X_3m)²-(D_nm) ²=0

(Equation 1). Taylor development gives whexe i=1, 2 , 3 . . n

(Equation 2). (Equation 3) T h e

approx imat i on gives the following linear compound equation, if one chooses to disregard terms with degree>1 ( Equation 4 ) .

The solution of least squares of the over-determined compound equation generally can be written as following iteration formula where k=1, 2 , 3...

(Equation 5).

The mobile computer can now with this relationship iterate itself to the position of the mobile nodes with good accuracy. The calculated position (X_1m, X_2m, X_3m) must not always conform completely with the exact position (X^* _1m, X^* _2m, X^* _3m) of the mobile unit. To obtain a measure of how good conformity the calculated position (X_1m, X_2m, X_3m) has with the exact position (X^* _1m, X^* _2m, X^* _3m,) of the mobile node, the following relationship is defined (equation 6)

(TRACE(A) = the sum of the diagonal elements in the matrix A)

C_m = (J^TJ)^-1 (equation 7)

The CGU-scalar shows the disturbance sensitivity of the calculations for the present configuration of the reference nodes and should correspond to the requirement of: 0<CGU_m< CGU_max so that the deviation of the calculated position (X_1m, X_2m, X_3m) of the mobile nodes not with certainity is greater than the promised system performances.

To discover faultiness in the distance matrix D_m with respect to measured distances the residual vector R_m is defined according to the following:

(Equation 8). The residual vector R_m shows the difference between the measured distances between the mobile node and the reference nodes and the corresponding distance, which is obtained for the calculated position (X_1m, X_2m, X_3m) of the mobile node. None of the components of the residual vectors are allowed to be greater to amount than R_max, in order that a distance information should be estimated as reliable. The measured distances themselves always have a certain error, due to the limitations of the microwave technology, but that error is limited to ± 10 cm with the present technic. However errors, which can be larger are, for example, the scaling error of the reference nodes since this scaling is performed manually with conventional surveying methods, or that the reference nodes are moved unintentionally. After the computations the mobile node position (X_1m, X_2m, X_3m), the residual vector R_m, and also the CGU_m-scalar is stored in the mobile system database 31. The system enables package intermediated data communication between the central unit and the mobile computer units, and these messages are called message packages. The basic principles of the system at data communication, according to fig. 5, are: always to acknowledge the transmitted messages by the transponder before the system regards that the message is arrived. The transmitter 19 transmits the message package 23 via a selected communication path, after which the transponder 20 accepts the message. The transponder retransmits an acknowledgement 22 of the received message through the same communication path. The acknowledgement is received by the transmitter and the data transmissions thereby are considered as successful by the system. Each message package 23, see fig. 6, can have the following basic content, i.e. transmitter identity 24, transponder identity 25, user message 21, system message 26 and also control information 27, such as the checksum and the register number.

The message transmission, according to fig. 7, between the mobile computer 8 and the central unit 9 occurs at same time during the time period, wherein the mobile node 7 measures the distances to all reference nodes 5 and 6 detectable to it. The message package 22 or 23 can have the following path: mobile computer - mobile node - data reference node 5 - central unit 9.

In the central unit 9 and in each mobile computer 8 are provided transmission queues 33 and 42 respectively, and reception queues 34 and 41 respectively, for user messages 21. The user messages are data messages from and to the different application-specific software 59 and 76 (fig. 9b), which are executed in the system. A user message can, for example be a control instruction from a user 3 or the control centre 13 to a working machine in the system volume 4. In the reception queues 34 and 41 the application specific software can fetch the user messages transmitted to it and it can place the user messages, which shall be sent to some one in the system, in the transmission queues 33 and 42. The central unit with the mobile computers subsequently manages the administration of the message flow between the different units in the system.

The message packages 22 and 23 generally can travel a number of paths, according to fig. 7, between the mobile computer 8 and the central unit 9, the reason is that the mobile node 7 always, according the definition, has at least one data reference node 5 detectable when the mobile node itself is in the system volume 4. To obtain an optimum utilization of the data transmission possibility a communication path 28 must therefore be selected for the data transmission. In the system the communication path is always selected by the mobile computer and executed as follows. From the mobile system database 31 can be red out, with which reference nodes 5 and 6 contact has been established at the last distance measurement, and also which of these reference nodes are data reference nodes. One of these data reference nodes is selected, whereby the communication path is determined.

Immediately after, the following message exchange procedure is initiated by the mobile computer 8, according to fig. 8 and 11. The message package 36, which is to be sent to the central unit 9 is formed by inserting the topmost user message 21 in the transmission queue 33, if there is any, in the user message portion 38 of the message package. System data 35 from the mobile database 64 regarding the position (X_1m, X_2m, X_3m) of the mobile nodes 7, the CGU_m-scalar, the residual vector R_m as well as possible other system information are inserted in the system message part 39 of the message package. The receiver identity number and the user identity number 37 are added in the message package. Finally the checksum as weij as the register number 40 are determined. The message package is now clear for transmission and is sent through the communication path 28 selected by the mobile computer to the central unit.

The message received by the central unit 9 is immediately inserted in the reception queue 41, according to fig. 8 and 13, after the system message 39 has been removed from the message package and stored in the system portion 43 of the administrator database. Subsequently the central unit starts a corresponding process for arranging a reply message package 44 to the mobile computer 8. This message functions also as an acknowledgement for the message sent by the mobile computer 8. The central unit takes the topmost user message 21 in the transmission queue 42, if any, and places it in the part of the reply message 44 for the user message 46. Possible system information is fetched from the system part 43 of the administrator database and placed in the message package part for the system data 47. The receiver identity number and the user identity numbers 45 are placed in the message package. Finally the checksum as well as register number 48 are determined. The reply message package is now completed and transmitted through the same communication path 28 back to the current mobile computer.

The mobile computer 8 receives the reply message 44 and places it in the reception queue 34, after the system message 47 has been removed from the message package and stored in the system part of the mobile database 35. The received message acts as an acknowledgement of the message 36 initially send by the mobile computer. The mobile computer now considers its transmission successful and terminates the message exchange procedure by providing an acknowledgement 49 of the message package 44 sent by the central unit. The acknowledgement consists of the transmitter identity and the transponder identity 50, the checksum as well as the register numter 53. No user message 51 and system message 52 are sent with this terminating acknowledgement 49. The central unit 9 receives the acknowledgement and the message exchange procedure is considered terminated.

The above described procedure implies that a data transmission is always initiated by the mobile computer 8 and terminated by the same. The central unit 9 replies always to incoming messages from the mobile computers in the system volume 4 and thereby never itself takes the initiative of a data transmission. The system functions at the mobile unit 2 are managed and controlled by the mobile computer 8. The mobile computer in fig. 9a, is the unit, to which are connected: the microwave based distance measurement equipment 7 as well as possible peripheral equipment such as display 54, keyboard 55, printer 56, electronic compass 57 and/or other equipments 58 specific for the application. The mobile computer as well as the peripheral equipment are mounted, e.g. in or on a machine part or vehicle, entirely depending on the application in which which the system 1 is used.

In fig. 9b, which discloses the mobile computer 8, a number of softwares 60 are executed, i.e. positioning software 61, communication software 62 as well as application specific software 59. The positioning software administrates the positioning determination, both regarding the measurement of the distance to the reference nodes 5 and 6 and the calculation of the position (X_1m, X_2m, X_3m), the CGU_m-scalar as well as the residual vector R_m. The communication software administrates the message flow between the mobile computer and the central unit 9. The application specific software, which is executed in the mobile computer, is the software, which mobile unit 2 uses in different ways. Application specific software can, for example, include software with the task to present the position of the mobile nodes 7 on a display 54 connected to the mobile computer.

The mobile computer, according to fig. 9, also maintains a local database, called mobile database 64. The mobile database is divided in a system part 31 and an application part 63. In the system database 31 are stored the reference node data 65, the measured distance to the reference nodes 66, the position (X_1m, X_2m, X_3m) 67 of the mobile nodes, the CGU_m-scalar 69, the residual vector R_m 68, and also other system specific data. In the system database are also provided the transmission queue 33 and the reception queue 34 for the user messages 21. The application database 63 contains data, which must be stored by the application specific softwares 59. The mobile database can physically be a non volatile memory unit such as a hard disc, a disc unit, a flash memory or the like.

The central unit has three principal tasks, i.e. the administration of the message flow between the central unit and the mobile computers 8, supervision and maintenance of the position determination functions in the system as well as constituting an interface between the system and the application specific software of the users 3.

One or more data reference nodes 5 arranged inside and/or outside the system volume 4, are connected to the central unit (fig. 10) via the extension 75, radio modem 30, wire 29, optical fibre, a combination of these or the like. Further, the computer units 12, which serve the users 3, are connected, e.g. via a conventional computer network 11. The users hereby are connected to the central unit and the functions, which are offered by this. A number of softwares 78, such as control software for the positioning functions 80, communication software for the administration of the message flow 81, software for attendance and supervision of the operator 10 of the system 82 as well as other application specific software 76 are executed in the central unit.

In the central unit a database called administrator database 79 is maintained. The database is divided into two parts, i.e. a system part 32 and an application part 77. The system part contains information about all reference nodes 86, all positions 83 (X_1m, X_2m, X_3m) of the mobile nodes 7, the CGU- scalar 85, the residual vectors (R.84, m=1, 2, 3 ..., m_max), transmission queues 42 for each user message 21 of the mobile units, reception queue 41 for incoming message package 22 and 23, as well as other system specific information. The application part 77 of the administrator database 79 contains data, which the application specific software 76 need to store and which can be available for all users 3 through the computer units 12. The administrator database 79 is physically a non volatile memory unit with large amount of storage capacity such as a hard disc or the like.

Since the position determination data 43 of all mobile units 2, such as the positions (X_1m, X_2m, X_3m) 83 of the mobile units, the CGU_m-scalars 85, the residual vectors R_m 84 (m=1, 2, 3 ..., m_max) are collected and stored in the system database 32 of the central unit, it is possible to monitor the positioning functions in the system.

The control software for positioning functions 80, according to fig. 10, detects and warns when the mobile nodes 7 are outside or inside the confines of the system volume 4. This is detected by means of continuous monitoring of the scalars CGU_m 85 and the positioning declarations (X_1m, X_2m, X_3m) 83 by the programme for all mobile nodes, which are stored in the system database 32. Errors are detected when a CGU_m-scalar of a mobile node exceeds its maximum permitted value, CGU_max. When the CGU_m-scalar exceeds the maximum value, the mobile computer 8 can not decide the position of the current mobile node with the precision required by the current application. This type of error, for example can be addressed by the following method, either in that the current mobile node arranged by a mobile unit, relocates it into the system volume or by means of enlargement/displacement of the system volume to cover the volume, within which no acceptable CGU- scalar is obtained. Enlarging/displacing of the system volume is carried out by means of moving the reference nodes 5 and 6 via a suitable method and/or increasing the number of reference nodes and placing these in such a way, that the CGU-scalar is kept within the permitted interval.

The control software for the positioning functions 80 detects and warns for erroneous range-findings between the mobile nodes 7 and the reference nodes 5 and 6 by monitoring the residual vectors 84 of all mobile nodes present in the system volume 4, and which are stored in the system database 32. Erroneous range-findings can depend on defective distance measurement equipment, but also on erroneously scaled reference nodes. The placement of the reference nodes can gradually be dislodged for different reasons. This type of error is detected when some component of the residual vector R_m of a mobile node exceeds the value of R_max. If this type of error is detected for a number of residual vectors R_m of the mobile nodes, one or more reference nodes can be pointed out as defective or wrongly scaled.

At the central unit 9 the system operator 10 performs the maintaining job, which is required for the enforcement of the system functions and performance. The system operator, through the supervision software 82, controls that the guaranteed system performances are maintained for all the mobile units 2 included in the system volume 4. The system operator monitors the message flow in the system through the communication software executed in the central unit 81. The system operator can also edit the transmission 42 and reception queues 41 of the central unit, for example when messages to a specific mobile computer do not go through. The reason for it e.g. can be that a machine is being repaired and therefore is not within the system volume. Then it can be required that user messages 21 are removed, which are inserted in the transmission queue of the central unit during the time the machine is being repaired. Registration of the reference node data REF_m 86 is performed by the operator and stored in the system database 32. An example:

The following example describes use of the system according to the invention in an opencast mine. The example shows an application being used to increase the efficiency of the drilling and blasting procedure.

The work step at drilling of an area 70 being blasted, follows the following known example of procedure, according to fig. 14.

A drilling plan for the drill holes 71 for the current area are procured by the mine indicators. Then the contemplated drill holes are measured manually with tape-measurement and marked 72 with red coloured stones.

The drill operator then manoeuvres the drill 73 between the marked holes and drills so close to each marking as possible. Sometimes at winter, the problem is that snow and slush blurs the markings. To obtain as even level on the area as possible, the mine measurer calculate approximately how deep the drill holes should be drilled. Desired drill hole depths are not calculated for each drill hole, but indicated approximately for different areas on the drill map. This implies that the level of the bottom for the different drill holes can vary in order of meter. Sometimes the holes can not be drilled in turns, due to different reasons, e.g. access difficulties. This can entail dislocation of drill hole patterns, which means that drill holes are drilled unnecessarily. This misdrilling results in more explosive consumption. When a drill hole is completed the number of drill holes as well as the depth of the hole are registered manually on paper for each hole. As the charging proceeds the holes are measured manually by the mine measurers with geodimeteri . When all holes are drilled and charged, the charge is exploded and the rock is thereby clear for loading.

With a system according to the invention, the following changes will be observed. Inside or on each drill 73 a mobile node 7 is installed having a mobile computer 8 with display 54 connected thereto. At the same time the positioning programme 61, the communication software 62 as well as the application specific software 59 are executed in the mobile computer. This implies that the mobile computer now has access to the position of the machine in X, Y, Z with a precision of about ±10 cm. The mobile unit also has access to the data communication between the mobile computer and the central unit 9 at control centre 13. Drilling maps can therefore be transmitted electronically to each drill. An electronic compass is also connected to the mobile computer. The electronic compass is used to orient the drilling map correctly in relation to how the drill is situated momentarily. Since the design of each machine and its dimension is known, the software knows exactly where the drill is in relation to the node. The application specific software shows a display image 87 (fig. 15) to the drill operator.

In the left part of the image the electronic drilling map 88 is shown. Intended drill holes are marked with a plus sign 89 and holes already drilled are marked with a white circle 90. The electronic drilling map is equipped with a magnification square 91, which helps the drill operator to fine manoeuvre the drill up to the intended drill hole. Further, the positions 92 of the drill are shown in X, Y and Z-coordinates. It is also possible to register the name 93 of the drill operator working at present. Drilling maps can now be sent electronically from the control centre 13 down to the drill. When a drill map is sent to the drill, it is possible to attach information about the blast area, i.e. the bottom 94 of the projected round area. With this information accessible, the mobile computer can calculate how deep the drill shall drill 95 to reach the intended bottom level. In the example is shown that the hole will be drilled 15.6 m deep. When a drill hole is completed, the drilling will be registered. This is done in the drill report square 96, directly at the right side of the drilling map. The drill operator indicates the drill hole number as well as how deep the hole is drilled, then the drill operator presses down the "drill hole completed" button. Input data about the drill hole, together with the exact position of the drill hole are then sent through the data reference node 5 to the central unit 9 in the control centre. This information becomes accessible for all users 3 connected to the system, as soon the message package 23 is received.

Advantages with the system are, for instance that the manual marking of the drill hole is omitted, the manual scaling of the drill hole after charging is omitted, the bottom of the blasted area becomes more levelled, the drilling pattern becomes more optimal, the explosive consumption is reduced, the work environment becomes better for the drill operators, paper administration of the drill maps is eliminated, statistical record is improved and the administration of the drill reports is reduced.

The reference numerals in the flow charts

Fig. 11

101: Start;

102: Build message package 36;

103: Data communication possible;

104: Select communication path 28;

105: Transmit message package 36;

106: Is the reply message 44 received?

107: Otherwise, wait for interrupt (time-out);

108: If reply message received, remove the system

message 47 from the reply message 44 and store this in the system part 35 of the mobile database;

109: Place the reply message 44 at the end of the

reception queue 34;

110: Remove the user message 38 sent recently, from

the transmission queue 33;

111: Arrange the acknowledgement 49;

112: Transmit the acknowledgement 49;

113: Message transmission completed.

Fig. 12

114: Start;

115: Wait until period dTm has lapsed after the latest measurement?

116: Activate mobile node;

117: Initiate the data communication;

118: Read measured distances;

119: Save the measured result in the system part of the mobile database 35;

120: Calculate the position 67, residual vector 68, CGU

69; 121: Save the calculation result in the system part of the mobile database 35;

122: Wait until message transfer completed;

123: If the message transfer not completed, wait for interrupt (time-out);

124: Data communication not possible;

125: Activate the mobile node, stand-by.

Fig. 13

126: Start;

127: Wait until any message package 36 received in

the input channel;

128: Remove the system message 39 from the message

package 36 and store it in the system part 43 of the administrator database;

129: Place the message package 36 in the reception queue

41;

130: Arrange the message package 44;

131: Transmit the message package 44;

132: Wait for acknowledgement 49;

133: If no acknowledgement, wait for interrupt (timeout);

134: Remove that useable message, which recently was sent in the message package 44, from the transmission queue.

List of Reference numerals

1. System 28. Communication path

2. Mobile unit 29. Wire

3. User 30. Modem

4. System volume 31. Mobile system

5. Data reference database

node 32. Administrator system

6. Reference node database

7. Mobile node 33. Transmission queue

8. Mobile computer 34. Reception queue

9. Central unit 35. System data

10. System operator 36. Transmitted message

11. Computer network 37. User/transponder

12. Computer unit identity

(user) 38. User message part

13. Control centre 39. System message part

14. Coordinate system 40. Register number

15. Opencast mine 41. Reception queue

16. Modulated carrier 42. Transmission queue wave 43. Part of the database

17. Synchronized system

signal 44. Reply message package

18. Distance 45. Transmitter-

19. Transmitter /transponder identity

20. Transponder 46. User message in the

21. User messages message package

22. Message package 47. System data

acknowledgement 48. Register number

23. Message package 49. Acknowledgement

24. Transmitter 50. Transmitter/- identity transponder

25. Transponder identity

identity 51. User message

26. System data 52. System message

27. Control information 53. Register number 54. Display 81. Communication software

55. Keyboard 82. Supervision programme

56. Printer 83. Position of the mobile

57. Electronic compass node

58. Peripheral 84. Database for R_m

equipment 85. Database for

59. Application CGU-scalar

specific software 86. Database for reference

60. Software node

61. Positioning 87. Display image

programme 88. Drill map

62. Communication 89. Plus sign

software 90. Circle

63. Application part 91. Magnification square in 64 92. Position of the

64. Mobile database drill

65. Reference node 93. Name panel

data 94. Blast area bottom

66. Distance to the level

node 95. Drill depth

67. The mobile node 96. Drill report

position

68. Residual vector

69. CGU_m-Scalar

70. Blast area

71. Drill hole

72. Marking

73. Drill

74.

75. Connection

76. Application specific

software

77. Application database

78. Software

79. Administrator database

80. Positioning control

Claims

1. Method for positioning in a system, for example through data exchange for use in projection works, flow control or the like, including:

- a number of mobile units (2);

- at least one central unit (9);

- a number of transmitter and/or receiver stations, so-called mobile nodes (7) and reference nodes (5, 6, 7), arranged inside and/or outside a volume (4), such as an opencast mine (15), a local transportation system or the like, whereby information exchange between the mobile units and the reference nodes (5, 6), and signal detection is performed by means of an information carrying medium, such as electromagnetic carrier waves or the like,

characterized in,

that in the central unit (9) and/or the mobile unit (2), the position of the mobile unit is generated in a number of coordinates, preferably in three coordinates (X, Y, Z), by measuring the distance to the reference nodes (5, 6), compiling and calculating the position,

and that the reference nodes (5, 6) arranged stationary but movable, are placed inside and/or outside the volume (4), so that at least three reference nodes (5, 6) are detectable from each mobile node (7) at each point within the volume,

and that the reference nodes are placed in such a way that a scalar (CGU) at each point within the volume (4) is kept within a minimum and maximum value (0≤CGU≤CGU_max).

2. Method according to claim 1,

characterized in,

that measured distances (18) are stored in a mobile system database (31) of the mobile unit.

3. Method according to claim 2,

characterized in,

that the distances (18) are stored in a first matrix (D_m), containing the results of the measurements of the system defined distances to the reference nodes (5, 6) as well as reference node data.

4. Method according to claim 3,

characterized in,

that reference node data are stored in a second matrix (REF_m), preferably containing the positions (XR_n,YR_n,ZR_n) of all the reference nodes (5, 6) placed inside and/or outside the volume (4), identification number (n) as well as node type (5 or 6).

5. Method according to claim 1, 2 and 3,

characterized in,

that the relation between the position (X_1m, X_2m, X_3m) of the mobile units, the first and the second matrix (D_m, REF_m) results in an unlinear and generally indefinite compound equation, which by means of alignment or the like, and by means of approximation or the like provides a linear compound equation, and through an equation solution or the like for the over determined compound equation receive an iteration formula, by means of which the mobile computer and/or the central unit can calculate its position with good precision, and

that the precision between the calculated position (X_1m, X_2m, X_3m)and the exact position (X^* _1m,X^* _2m,X^* _3m) of the mobile units is defined by means of the scalar (CGU_m).

6. Method according to claim 1,

characterized in,

that the communication between the different parts (8, 5, 7 and 9) is achieved by means of package intermediated data communication, so-called message package (22,23).

7. Method according to claim 1,

characterized in,

that the data communication is executed by always acknowledging the transmitted messages by the transponder before the system considers the message as received, and

that a transmitter (19) transmits the message package (23) via selected communication path, whereupon a transponder (20) accepts the message, and

that the transponder (20) resends an acknowledgement (22) for the received message via the same communication path, which acknowledgement is received by the transmitter before the data transmission is considered as successful.

8. Method according to claim 6,

characterized in,

that each message package (22,23) contains transmitter identity (24), transponder identity (25), transmitter message (21), system message (26) and also control information (27), such as checksum and record number.

9. Method according to claim 6,

characterized in,

that the message transmission between a mobile computer (8) and the central unit (9) is achieved during the same time period, as a mobile node (7) measures the distances to the reference nodes (5, 6).

10. Method according to claim 6,

characterized in,

that the message package (22, 23) has the following path:

mobile computer (8) - mobile node (7) - data reference node (5) - central unit (9).

11. Method according to claim 6,

characterized in,

that in the central unit (9) and/or in each mobile computer (8) is arranged transmission queues (33, 42) and transponder queues (34,

41) for the transmitter messages (21), and

that the transmitter messages are data messages from and to a different number of application specific software (59, 76), which are executed in the system (1).

12. Method according to claim 11,

characterized in,

that the application specific software collects the messages transmitted to it in a reception queue (34, 41), and

that the transmitter messages, which will be sent to somebody in the system, are placed in the transmission queues (33, 42).

13. Method according to claim 6,

characterized in,

that in the system (1) the communication path is selected by the mobile computer (8), by gathering reference nodes (5, 6) from a mobile system database (31), which nodes have been detected at the latest distance measurement, and also which of these reference nodes are data reference nodes (5), and

that one of these data reference nodes (5) is selected before the communication path is determined, and

that thereupon a message exchange procedure is initiated by the mobile computer (8), in that:

- the message package (36), which shall be sent to the central unit (9), is generated by means of a first user message (21) in the transmission queue (33), if such a message is available, being inserted in the user message part (38) of the message package, - system data (35) from a mobile data base (64), containing the position (X_1m, X_2m, X_3m) of the mobile nodes (7), the scalar (CGU_m), the residual vector (R_m) and also other possible system information are placed in a system message part (39) of the message package,

- a transponder identity number and a transmitter identity number (37) are added in the message package,

- a checksum and also a record number (40) is determined,

- the message package is transferred to the central unit via a communication path (28) chosen by the mobile computer.

14. Method according to claim 13,

characterized in,

that the message received by the central unit (9) is inserted in the reception queue (41), after the system message (39) has been removed from the message package and been stored in an administrator database system part (43),

that the central unit commences a corresponding process for arranging a respond message package (44) to the mobile computer (8), which message also serves as an acknowledgement for the message sent by the mobile computer (8), and

that the central unit takes the topmost transmitter message (21) in the transmission queue (42) and places it in the part of a transmitter message (46) of the new message package (44), whereby possible system information is fetched from an administrator system database (32) and inserted into a part for system data (47) of the message packages, and

that the transponder identity number and transmitter identity number (45) are added to the message package before a checksum as well as a record number (48) are determined and the respond message package is completed and sent via the communication path (28) back to the current mobile computer (8).

15. Method according to claim 1,

characterized in,

that distance measurement is executed in that the mobile node (7) transmits information carrying medium, which is received by the reference node (6), which in turn synchronizes an internal oscillator clock, or other time measurement means, with the received signal and resends the synchronized signal (17) to the mobile node, and

that the mobile node (7) receives the resent signal and compares the phase difference between transmitted and received signals, whereby the distance between the mobile node and the reference node is determined by means of the known distribution speed of the information carrying medium.

16. Method according to claim 15,

characterized in,

that information carrying medium consists of modulated carrier wave, and

that the distance measurement is executed using a number of different modulation frequencies.

17. Method according to claim 1,

characterized in,

that the distance from the mobile node (7) to each part of the mobile unit is known.

18. Method according to claim 6,

characterized in,

that a data transmission is initiated by the mobile computer (8) and terminated by the same, and

that the central unit (9) always replies to the incoming messages from the mobile computers in the system volume (4).

19. Method according to claim 1,

characterized in,

that when the mobile nodes (7) are arranged outside or inside the confines of the system volume (4), and/or

when erroneous distance measurements between the mobile nodes (7) and the reference nodes (5, 6) are obtained, a warning signal is triggered.

20. Method according to claim 19,

characterized in,

that position error is detected by supervising the scalar (CGU) and the position information (X_1m, X_2m, X_3m) for all mobile nodes, which are stored in the system database (32), and that the error is detected when the scalar (CGU_m) of a mobile node exceeds its maximal allowed value (CGU_max).

21. Method according to claim 19,

characterized in,

that a distance measurement error is detected via supervision of residual vectors ( 84 ) of all mobile nodes present in the system volume (4) and stored in the system database (32), and that the error is detected when the amount of any component in the residual vector (R_m) of a mobile node is exceeded.

22. Method according to claim 13,

characterized in,

that the response message (44) received by the mobile computer (8) from the central unit (9) is inserted in the reception queue (34), that the system message (47) is removed from the message package and stored in the system part (35) of the mobile database, that the mobile computer starts arranging the message package (49) as an acknowledgement for the message package (44) sent by the central unit,

that the message package (44) includes transmitter identity, transponder identity (50), checksum and also the record number (53),

and that the completed message package is sent to the central unit.

23. Device for positioning in a system, for example through data exchange for use in projection works, flow control or the like, including:

- a number of mobile units (2);

- at least one central unit (9);

- a number of transmitter and/or receiver stations, so called mobile nodes (7) and reference nodes (5, 6, 7), arranged inside and/or outside a volume (4), such as an opencast mine (15), a local transportation system or the like, whereby information exchange between the mobile units and the reference nodes (5, 6), and signal detection is performed by means of an information carrying medium, such as electromagnetic carrier waves or the like,

characterized in,

that in the central unit (9) and/or the mobile unit (2) are provided data processing means for generating the position of the mobile unit, preferably in three coordinates (X, Y, Z),

that the distances to the reference nodes (5, 6) provided inside and/or outside the system volume, which are placed in such a way that a scalar (CGU) at each point within the volume (4) is kept within a minimum and maximum value (0≤CGU≤CGU_max), are measured and calculated in a computer unit,

that the distance data is compiled in a computer unit (8 and/or 9) in which the position is calculated.

24. Device according to claim 23,

characterized in,

that at least one of the reference nodes (5) is arranged for data transmission, which node is connected to means for communication with other receiving/transmitting units (5,7,9).

25. Device according to claim 23,

characterized in,

that in and/or on the mobile unit (2) are arranged data processing means (8), connected to a transponder/transmitter unit (7) for reception and transmission of the information carrying medium, and which data processing means (8) includes processing unit and storing unit for received, transmitted and calculated data.

26. Device according to claim 23,

characterized in,

that in the central unit (9), the data processing unit is arranged, which is connected to the transponder/transmitter unit (5) for reception and transfer of information, and which data processing unit includes processing unit and storing unit for received, transmitted and calculated data.