GB2490679A

GB2490679A - Control of work machine to avoid damage to utilities

Info

Publication number: GB2490679A
Application number: GB1107705.4A
Authority: GB
Inventors: Jonathan Guest
Original assignee: JONATHAN KEITH GUEST
Current assignee: JONATHAN KEITH GUEST
Priority date: 2011-05-09
Filing date: 2011-05-09
Publication date: 2012-11-14
Also published as: GB201107705D0

Abstract

A machine, such as an excavator or earth moving machine, includes a location system (fig.2: 13, 14, 15) for determining the location of a tool mounted on the machine. The location system may be a GPS receiver. The location sensor may be mounted on or near the tool or mounted on the machine. The position of the tool may be found from the position of the sensor on the machine by determining the angles at which arms of the machine extend from their respective pivots (fig.6). The machine holds data indicating prohibited locations of the tool. The machine compares the determined location of the tool with the stored data and if the determined location of the tool is within a predetermined distance of a prohibited location, the operation of the machine is restricted or the machine is made inoperable. The system protects against damage to utilities such as pipes and cables fig.1: 3, 4, 5, or overhead lines fig.1: 6, by tools such as buckets or scrapers attached to work machines such as diggers, trenchers and the like.

Description

A MACHINE AND A METHOD FOR CONTROLLING ITS OPERATION

The present invention relates to a machine and a method for controlling operation of the machine. More particularly the invention relates to the control of a machine based upon location data. The invention has particular but not exclusive, applicability in controlling a machine such as an earth excavating machine based upon the location of components of a utilities infrastructure.

Developed countries have a highly developed utilities infrastructure providing basic services to homes and businesses. Such services typically involve the supply of water, electricity and natural gas as well as wired telecommunications services. In order to conveniently provide these services, pipes and cables are passed underground so as to enable widespread provision of the services without taking up space above the ground.

From time to time it is necessary to excavate a particular part of the ground. For example, such excavation might be necessary to provide access to components of the utilities infrastructure located below the surface of the ground for the purpose of maintenance. It is often desirable to carry out such excavation using heavy duty earth excavation machines. However, great care is required to ensure that such machines do not impact with components of the utilities infrastructure in such a way as to cause damage to the components of the utilities infrastructure. For this reason it has become desirable to be able to accurately locate components of a utilities infrastructure located underground so as to alert an operator of an earth excavation machine to the location of such components. * S I

* * It is known to carry out investigations in an area of interest to determine the location of * ISIS.

* utilities components and to use such investigations to generate utility location data. For cc. example, sub-surface utility infrastructure location devices and air vacuum excavation *. 30 techniques are often used to locate components of a utilities infrastructure and generate utility location data. S. SI * S * * .

Utility location data is often generated when work in a particular area is planned.

Subsequently, when work is to be carried out, the utility location data is used to mark the ground surface to indicate the location of utilities components, and a depth at which the utilities components are located. An operator of the earth excavation vehicle can then operate the vehicle with reference to the ground markings so as to avoid impact with the utilities components. However, experience has shown that even with such markings, from time to time earth excavating machines are operated in the location of components of a utilities infrastructure in such a way as to cause damage to these components.

It is an object of some embodiments of the invention to provide a method for controlling a machine relative to a prohibited location, such as a location at which a component of a utilities infrastructure is located.

According to a first aspect of the invention, there is provided a computer-implemented method for controlling a machine, the method comprising: reading data indicating prohibited locations; determining a location of a tool mounted on the machine; and comparing the determined location with the read data and if the determined location is within a predetermined distance of one of the prohibited locations, restricting operation of the machine.

In this way, a machine (such as a vehicle adapted for earth excavation) can be controlled so as to be inoperable when proximate particular prohibited locations. Where there is a risk that operation of the machine proximate to particular prohibited locations will cause damage, the method therefore mitigates the risk of such damage.

For example, where the machine is adapted for earth excavation, that tool may be an earth removing bucket. ln other embodiments the tool may be a compactor, an earth drill, a set of forks, a hammer or breaker, a grab tool, a patch planer, a shovel, a grinder, a shovel, a grinder, a sweeper, a trencher, a ripper tool, a man rider or a piling attachment. Indeed, the tool may take any suitable form for the operation(s) to be * carried out by the machine. It may be desired to prohibit operation of the machine where such operation would damage components located underground. S..

The data indicating prohibited locations may indicate locations of utilities. The utilities * may be selected from the group consisting of subterranean utilities and overground utilities. The utilities may be selected from the group consisting of fluid carrying conduits (e.g. gas or water pipes) and cables (e.g. communications or electricity cables).

Determining the location of a tool mounted on the machine may comprise reading data from a location sensor mounted at or near a location of the tool. The location sensor may take the form of an antenna adapted to receive signals useful in the generation of location data. Such signals may be transmitted from sateUites arranged to transmit signals usable to generate location data.

Determining the location of the tool mounted on the machine may comprise reading data from a location sensor (which may take the form described above) mounted remote from the location of the tool and processing data read from the location sensor to determine the location of the tool. For example, the location sensor may be located on another part of the machine than that on which the tool is mounted.

The method may further comprise storing data defining a relationship between a location of the location sensor and the location of the tool and determining the location of the tool based upon the stored data. The tool may be moveable relative to the location of the location sensor and the. method may further comprise determining relative location data indicating the location of tool relative to the location of the location sensor and determining the location of the tool based upon the determined relative location data. For example, the tool may be mounted on at least one arm moveable = about a respective pivotanddetermining the relative==location data may comprise determining an angle at which the or each arm extends from its respective pivot. Such angles may be determined using accelerometers or other angle sensors. The or each * *. : arm may be linearly moveable and may be provided with sensors sensing such linear * ** movement,

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* . The data indicating prohibited locations may be three-dimensional location data. The data indicating prohibited locations may comprise latitude, longitude and altitude data. S'S

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S. Determining the location of the tool mounted on the machine may comprise determining the location of the tool in three dimensions. Determining the location of the tool may comprise determining the location of the tool based upon Global Positioning System (GPS) data and/or data from another location system.

Restrictftig operation of the machine may comprise restricting operation of the tool.

Restricting operation of the machine may comprise restricting movement of the tool.

Restricting operation of the machine may comprise preventing operation of the machine or some functionality thereof. Restricting operation of the machine may comprise activating safety cut-off circuitry of the machine.

The methods provided by the first aspect of the invention can be implemented by way of computer programs which can be carried on suitable carrier media. Such carrier media can be tangible non-transitive carrier media (e.g. disks) or intangible carrier media (e.g. communications signals).

A second aspect of the invention provides a control device for a machine, the control device comprising electronic circuitry configured to carry out a method as described above.

The electronic circuitry may comprise a memory storing processor reading instructions; and a processor configured to read and execute instructions stored in the program memory. The instructions may comprise instructions arranged to cause the processor to carry out method as described above.

A third aspect of the invention provides a machine comprising: a location sensor; a tool mounted on the machine and controllable by the machine; and processing circuitry configured to: read data indicating prohibited locations; determine a location of the tool based upon data provided by the location senor; compare the determined location with the read data and if the determined location is within a predetermined distance of one * : * of the prohibited locations, restrict operation of the machine.

S..... * S

* The machine may further comprise an electronic data storage device stored the data indicating prohibited locations. The machine may be an earth excavating machine. S..

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Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an illustration of machine showing is location relative to various parts of a utilities infrastructure; Figure 2 is a schematic illustration of components provided on the machine of Figure 1; Figure 3 is a schematic illustration showing the processing system of Figure 2 in further detail; Figure 4 is a flowchart showing processing carried out by the processing system of Figure 2; Figure 5A is a schematic illustration showing a two-dimensional space divided into a grid of regular cells; Figure SB is a schematic illustration showing a three-dimensional space divided into an array of regular cells; Figure 6 is a schematic illustration showing part of the machine of Figure 1 in further detail; Figure 7 is a flow chart showing processing carried out by the location system of Figure 2 to locate a particular part of the machine; and Figure 8 is a schematic illustration showing angular relationships between components of the machine.

Referring to Figure 1, there is illustrated an earth excavating machine 1. The machine is located on a ground surface 2 beneath which are located parts of a utilities * infrastructure in the form of fluid carrying conduits 3, 4 and a cable 5. The conduits 3, 4 can carry liquids or gasses and may be part of, for example, a water supply system, a waste water drainage system or a gas supply system. The cable 5 may be, for example, a fibre optic cable or a cable comprising a metallic conductor, such that the * cable 5 may be a communications cable or an electricity supply cable.

Above the ground surface 2 there is located a further cable 6 supported by appropriate supports (not shown) which are mounted on the ground surface 2. The cable 6 may take a similar form to the cable 5.

The earth excavating machine I is moveable along the ground surface 2 and comprises a too) 7 in the form of an earth excavating bucket moveable relative to an arm 8 on which it is mounted. The arm 8 is in turn connected to and moveable relative to an arm 9 which is connected to a body 10 of the earth excavating machine 1.

Movement of the tool 7 relative to the arm 8 and movement of the arms 8 and 9 is controllable by a human operator using controls provided in a driver's cab 11 of the earth excavating machine 1. The tool 7 is operable to remove material making up the ground surface 2 so as to, for example, provide access to the parts of the utilities infrastructure located therebe)ow.

When the earth excavating machine is operated to remove material making up the ground surface 2 it is highly desirable that it is operated such that the tool 7 does not come into direct contact with parts of the utilities infrastructure, so as to avoid damage to the utilities infrastructure.

Mare particularly, when removing material below a part A of the ground surface 2 above the conduit 3, the tool 7 should only be operated at a depth below the ground surface 2 wflcisles thanthat..indicatedby an-arrow-ar Similarly when-removing material below a part B of the ground surface 2 above the conduit 4, the tool 7 should only be operated at a depth below the ground surface 2 which is less than that indicated by an arrow b. Similarly, again, when removing material below a part C of the ground surface 2 above the cable 5, the tool 7 should only be operated at a depth below the ground surface which is less than that indicated by an arrow c. It will be appreciated that operating the tool 7 in one of the areas A, B, C at a depth greater than is indicated by a respective one of the arrows a, b, c risks damage to the utilities S.. . * infrastructure. Furthermore, if one the conduits 3, 4 carries a noxious substance (e.g. * .. natural gas) an impact between the tool 7 and one of the conduits 3, 4 may result in * escape of the noxious substance to the atmosphere, thereby causing a safety risk both to an operator of the earth excavating machine I and the wider public. An impact between the too) 7 and the cable 5 can again pose a safety threat if the cable 5 carries electricity, more particularly a threat of electrocution to an operator of the earth excavating machine 1.

In addition to the potential for damage and danger arising from operating the tool 7 at too great a depth below some parts of the ground surface 2, operating the tool 7 at too great a height in the vicinity of the cable 6 can cause damage and danger similar to that described above in relation to the cable 5.

Components provided on board the earth excavating machine 1 to prevent the tool 7 adversely affecting the utilities infrastructure by impacting on conduits or cables are now described with reference to Figure 2.

A processing system 12 is connected to a location system 13 which provides location data relating to a location of the earth excavating machine 1. The location system 13 can be a Global Positioning System (GPS)-based location system which is arranged to receive signals from GPS satellites via an antenna 14 and to use the received signals to generate location data which is provided to the processing system 12. The location system 13 further comprises a radio antenna 15. The radio antenna 15 receives signals from a GPS base-station (not shown) which can be used to improve the accuracy of the generated location data, as described in further detail below.

The processing system 12 provides an output to a relay 16 which is arranged to control a control system 17. In particular, based upon data received from the location system 13, and processing described below, the processing system 12 can provide an output to the relay 16 which in turn controls the control system 17 to stop operation of the earthexcavating machine 1.

The processing system is connected to a display 18 which is located within the cab 11 * * of the earth excavating machine 1 so as to provide information to an operator of the * S S * 30 earth excavating machine 1. The display 18 may be a touch-screen display providing a convenient combined input/output mechanism. ** S.

* The processing system 12 can take any suitable form. For example electronic circuitry arranged to carry out the processing described below can be provided (for example using one or more application specific integrated circuits in combination with other suitable components). In some embodiments the processing system 12 is a programmable computer having a form as iUustrated in Figure 3.

The processing system comprises a CPU 12a which reads and executes instructions S stored in RAM 12b. Data processed by the instructions is also stored in the RAM 12b.

Non-volatile storage 12c in the form of a hard disk drive or solid-state memory (e.g. Flash memory) is also provided, and the CPU 12a controls the transfer of data from the non-volatile storage 12c to the RAM 12b. The processing system further comprises an input/output (I/O) interface 12d to which the display 16, and other I/O devices (not shown) are connected. ln the described embodiment the processing system comprises a network interface 12e allowing the processing system 12 to connect to a computer network. The network interface 12e is preferably a wireless network interface allowing the processing system to connect to wireless networks, for example networks operating according to IEEE standard 802.11 and its variants. The CPU 12a, RAM 12b, non-volatile storage 1 2c, I/O interface I 2d, and network interface I 2e are connected together by a communications bus 12f.

The non-volatile storage 12c stores utility location data which is used by the processing system 12 in the manner described below. The utility location data indicates geographical locations of a plurality of components of a utilities infrastructure. For example, the utility location data may comprise details of the locations of all components of the utilities infrastructure in a particular geographical area (for example a particular site on which utilitiemsThtenapce wOrkis tO take jla6e): A number of different instances of utility location data may be stored in the non-volatile storage 12c, each relating to a different geographical area (for example a different site on which utilities maintenance work is to take place).

Referring to Figure 4, processing carried out by the processing system 12 is now * ,* described.

At step SI user input is received indicating utility location data to be used for subsequent processing. Such user input can take the form of a path name within a * filesystem operating on the processing system 12, locating one or more files stored in the non-volatile storage 1 2c of the processing system 12. Such input may be received via the display 18 having the form of a touch-screen displays, alternatively, such input may be received from a remote device, for example another computer which is in communication with the processing system 12, for example over a wireless computer network via the network interface 12e.

At step 52 the processing system retrieves utility location data indicated by the user input from the non-volatile storage 12c and stores at least part of the retrieved data in the RAM 12b.

At step 83 location data is received by the processing system 12 from the location system 13 providing data associated with the location of the earth excavating machine 1. At step 54, the processing system 12 compares the location data received at step S3 with the utility location data indicated by the user input of step Si. If the location data associated with the earth excavating machine I indicates that the earth excavating machine I is located within a predetermined distance of the utility location data retrieved at step $2, then processing passes to step $6 and continues as described below. If, however, the location data received at step S3 indicates that the earth excavating machine 1 is insufficiently close to locations associated with the utility location data retrieved at step $2, an error message is presented to the user at step S5 (for example on the display 18 or another appropriate output device) and processing returns to step Si.

Steps SI to 55 represent a set-up operation arranged to ensure that the processing system 12 is provided with appropriate utility location data for use in subsequent processing described below.

Steps S6 to SQ provide a loop through which the processing system repeatedly passes.

At step 36 location data is received by the processing system 12 from the location * system 13 indicating a current location of part of the earth excavating machine 1. At step 57 a check is carried out to determine whether the location indicated by the location data received at step S6 indicates that the earth excavating machine I is * *. proximate one or more components of a utilities infrastructure such that operation of * the earth excavating machine 1 should be stopped so as to prevent damage to the components of the utilities infrastructure. If the earth excavating machine is determined not to be proximate to one or more components of the utilities infrastructure processing returns to step 56.

If, however, the earth excavating machine 1 is determined to be proximate one or more components of the utilities infrastructure processing passes to step 88 where operation of the earth excavating machine is stopped by the transmission of an appropriate signal from the processing system 12 to the relay 16. Processing then passes to step 89 where a signal is received by the processing system 12 indicating that an operator of the earth excavating machine I has restarted the machine.

Processing then returns to step 56.

The processing of step S7 to determine whether the earth excavating machine I is proximate one or more components of a utilities infrastructure can conveniently be carried out using a grid-based representation of the area represented by the utility location data. Figure 5A shows a two dimensional representation of a space of interest divided into a grid of cefls of predetermined size. The utility location data can be used to determine cells which include a component of the utilities infrastructure. In the example of Figure 5A the utility location data indicates that components of the utilities infrastructure are arranged so as to occupy a straight line 1,9 of the grid of cells.

The location data received at step S6 of Figure 4 can similarly be processed to determine a cell 20 of the grid in which a part of the earth excavating machine 1 is currently located.

In such an arrangement the processing of step 87 can be based upon a determination of whether a cell adjacent to a cell in which the part of earth excavating machine 1 is currently located is occupied by any components of the utilities infrastructure. Such cells are indicated by a border 21 in Figure SA. If a part of the earth excavating machine is located within the area defined by the border 21, it is determined that the earth excavating machine is proximate a component of the utilities infrastructure and its

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operation is stopped.

*.s *S * It was described with reference to Figure 1 that it is preferable to control operation of the earth excavating machine 1 based upon three dimensional data (i.e. not two-dimensional data as is illustrated in Figure 5A). The approach to the processing of step S7 described with reference to Figure SA can be extended to three dimensions, as shown in Figure 58. Here, a three dimensional space to which the utility location data rerates is divided into an array of cells, each cell being a cube. The utility location data is processed to determine cells of the array which include a component of the utilities infrastructure. For example, a cell 22 comprises some component of the utilities infrastructure. A cell in which a part of the earth excavating machine I is located is determined, and a check is then carried out to determine whether the cell in which a part of the earth excavating machine 1 is located is adjacent to a cell including a component of the utilities infrastructure, and hence whether the part of the earth excavating machine I is proximate a component of the utilities infrastructure.

It has been described above that the location system 13 (Figure 2) provides data indicating a location of part of the earth excavating machine 1. It is preferable that the location data indicates the location of the too? 7 as accurately as possible. As such, in one embodiment the antenna 14 is mounted on the tool 7 so as to provide location data associated with the tool 7.

While locating the antenna 14 on the tool 7 provides the desired location data, in some circumstances locating the antenna 14 on the tool 7 is disadvantageous given that the tool 7 interacts with the ground making the antenna susceptible to damage. As such, in some embodiments, the antenna 14, as well as the location system 13, is mounted in or on the cab 11. In such a case additional processing is carried out by the processing -system 12 to accurately locate the tool 7.

Figure 6 shows some components of earth excavating machine I in further detail. In particular it can be seen that the antenna 14 is mounted atop the cab 11 of the earth a. * * . * * * excavating machine 1. The arm 9 extends from the cab 11 at an angle a to the horizontal H, while the arm 8 is pivotally connected to the arm 9 and extends from the * ,, arm 9 an angle f3 to the horizontal.

Figure 7 shows processing carried out to determine the absolute position of the tool 7.

At step SlO data is received from the location system 13 providing location data based upon the location of the antenna 14. At step Sli, data is received from a sensor sensing the angle a of the arm 9 relative to the horizontal H. Similarly, at step 512 data is received from a sensor sensing the angle j3 of the arm 8 relative to the horizontal.

The sensors sensing the angles a and 3 can take any suitable form. For example each of the arms 8, 9 can be provided with a respective accelerometer sensing proper acceleration of the respective arm 8, 9 which is indicative of the angular orientation of the arms 8, 9. Alternatively other angular sensors may be used.

At step 13 the values of the angles cx and f3 together with known data indicating the lengths LI, L2 of the arms 9, 8 are used to determine a vector v being a vector between a point at which the arm 9 meets the body of the earth excavating machine I and a point X at which the tool is located. At step 813 the vector v is combined with a known vector Vi which indicates the known relationship between the position of the antenna 14 and the point at which the arm 9 meets the body of the earth excavatingmachine.

Determination of the vector v. is now described with reference to Figure 8 which shows schematically the angular relationships and lengths between the arms 8, 9. The determination is based upon standard trigonometry.

A first right angled triangle p, q, L1 is constructed, such that p and q are given by: p=L1sina (1) q=L1cosa (2) * *25 A second right angled triangle r, s, L2 is constructed such that rand s are given by: * S**tS * S * S* * S S * S r=L2sin,B (3)

S S. S* S

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s-L2cosJ3 (4) A third right angled triangle x, y, v is constructed such that: x=s+q =L,cosfl+L)cosa (5) y=p+r -L1sina+L2sinfl Given Pythagoras' theorem, v is then given by: (7) substituting (5) and (6) into (1) gives: v=jiosa+L2cosfl)'±(fi sina+L2sinfl)2 (8) It will be appreciated that the above equations apply when the arms 8, 9 have fixed length. However, it will also be appreciated that if the arms 8, 9 have adjustable length (e.g. because they allow telescopic movement) the length of the arms 8, 9 can be sensed and appropriately processed using the processing described above. Similarly, where there are more than two arms b6nnecting the to=o 7 to the earth excavating machine 1, the principles described above can be modified to allow the location of the tool 7 to be determined. S. S * S I * IS

it has been described above that the location system 13 generates location data based upon signals received at the antenna 14. in some embodiments, location data so * S. generated is insufficiently accurate. As such, in some embodiments of the invention so-called correction-based location techniques are used. These rely upon location data generated by a further location system located in a known position. Location data generated by the further location system is compared to the known position and a difference between the location data generated by the further location and the known position is used to generate correction data. This correction data is then used by the processing system 12 to correct location data received from the location system 13.

Such correction-based location techniques are based upon an assumption that art error present in the location generated by the further location system is comparable to the error present in the location generated by the location system. Such an assumption arises because such errors often arise as a result of irregularities in the earth's curvature which are likely to affect the location system and further location system to a similar extent.

It will be appreciated that the location system 13 (and the further location system used to generate correction data, if used) can take any suitable form. In preferred embodiments of the invention the location data generated by the location system 13 is accurate to within about 40cm, and in moie preferred embodiments the location data is accurate to within about 20cm, more preferably to within about 6-8cm. In some embodiments a Novatel FIexGB-V1 G-RT2O-G GPS location system is used.

It will be appreciated that because the earth excavating machine 1 is typically used in harsh environments (e.g. outdoors and in environments with high levels of dust or dirt) all components shown in Figure 2 are preferably housed in a robust, sealed, enclosure.

For example, where the processing system 12 takes the form of a programmable computer it is preferred that the programmable computer has no fan so as to prevent the ingress of dust into the computer.

Although preferred embodiments of the invention have been described above, it will be appreciated that various mdftictios ca be made. Fol example; while the system has been described in relation to an earth excavating machine it will be appreciated that it can be applied to any moveable vehicle which it is desired to control relative to the location of components of a utilities infrastructure. For example the methods described above may be applied to any site vehicle including such vehicles as fork-lift trucks, cranes and cherry pickers. Furthermore, the invention finds application in vehicles intended to run along tracks such as railway tracks and intended to maintain 30 those tracks or utilities associated with the tracks (e.g. electricity cables). S. * * S

* * While control of a machine or vehicle relative to components of a utilities infrastructure has been described herein, it should be noted that the machine or vehicle can be controlled relative to the location of other features of a space of interest.

Furthermore, where references have been made herein to the Global Positioning System (GPS) it is to be appreciated that any location system, for example any Global Navigation Satellite System (GNSS) may be used in embodiments of the invention.

Examples of GNSSS include the GPS and also GLOSNASS, Galileo and Compass. S. S * a * * S.

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Claims

VCLAIMS: 1. A computer-implemented method for controlling a machine, the method comprising: reading data indicating prohibited locations; determining a location of a tool mounted on said machine; and comparing said determined location with said read data and if said determined location is within a predetermined distance of one of said prohibited locations, restricting operation of said machine.

2. A method according to claim 1 wherein said machine is an vehicle adapted for earth excavation.

3. A method according to claim I or 2, wherein said tool is an earth removing bucket.

4. A method according to any preceding claim, wherein said data indicating prohibited locations indicates locations of utilities.

5. A method according to claim 4, wherein said utilities are selected from the group consisting of subterranean utilities and overground utilities.

-Aeth6d according to claim 4 or 5, wherein said utilities are selected from the group consisting of fluid carrying conduits and cables.

S 7. A method according to any preceding claim wherein determining the location of *05551 * a tool mounted on said machine comprises reading data from a location sensor mounted at or near a location of said tool. a 0SS

8. A method according to any one of claim I to 6, wherein determining the location of the tool mounted on said machine comprises reading data from a location sensor mounted remote from the location of said tool and processing data read from the location sensor to determine the location of the tool.

9. A method according to claim 8, further comprising storing data defining a relationship between a location of said location sensor and the location of said tool and determining the location of said tool based upon said stored data.

10. A method according to claim 8 or 9, wherein said tool is moveable relative to the location of said location sensor and the method further comprises determining relative location data indicating the location of tool relative to the location of the location sensor and determining the location of the tool based upon said determined relative location data.

11. A method according to claim 101 wherein the tool is mounted on at least one arm moveable about a respective pivot and determining said relative location data comprises determining an angle at which the or each arm extends from its respective pivot.

12. A method according to any preceding claim wherein said data indicating prohibited locations is three-dimensional location data.

13. A method according to claim 12, wherein said data indicating prohibited locations comprises latitude, longitude and altitude data.

14. A method accbrdinjto any précéding claim, wherein determining the location of * the tool mounted on the machine comprises determining the location of the tool in three dimensions. * * S * S.

*.... 15. A method according to any preceding claim, wherein determining the location of the tool comprises determining the location of the tool based upon Global Positioning System (GPS) data.

*j* 30 16. A method according to any preceding claim wherein restricting operation of said : * * machine comprises restricting operation of the tool.

17. A method according to claim 16, wherein restricting operation of the machine comprises restricting movement of the tool.

18. A method according to any preceding claim, wherein restricting operation of said machine comprises preventing operation of the machine or some functionality thereof.S

19. A method according to any preceding claim wherein restricting operation of the machine comprises activating safety cut-off circuitry of the machine.

20. A computer readable medium carrying computer readable instructions configured to cause a computer to carry out a method according to any preceding claim.

21. A control device for a machine, the control device comprising electronic circuitry configured to carry out a method according to any one of claims 1 to 19.

22. A control device according to claim 21, wherein electronic circuitry comprises: a memory storing processor reading instructions; and a processor configured to read and execute instructions stored in said program memory, the instructions comprising instructions arranged to cause the processor to carry out method according to any one of claims ito 19.

23. A machine comprising: a location sensor; -= -=----- tool mounted on the machine and controllable by the machine; and processing circuitry configured to: read data indicating prohibited locations; determine a location of the tool based upon data provided by said location senor; compare said determined location with said read data and if said determined *. 30 location is within a predetermined distance of one of said prohibited locations, restrict * operation of said machine.

24. A machine according to claim 23, further comprising an electronic data storage device storing said data indicating prohibited locations.

25. A machine according to ctaim 24, wherein the machine is an earth excavating machine. *q. * S S * *SSI IS ass * S * 5 * 5 S * S. *SIS ** IS * S 5S S