Abstract:
A computer-implemented method for providing a warning including the steps: obtaining data relating to the location of a hazardous object and obtaining data relating to the location of a material handling machine. The computer to compare the location of the material handling machine to the location of the hazardous object and estimates a probability of a hazardous event occurring. If the estimate exceeds a threshold valve, a warning is issued by the computer.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a computer-implemented method for providing a warning. 
     BACKGROUND OF THE INVENTION 
     Known material handling machines such as excavators have a material handling arm assembly. The arm assembly may have an arm, known as a boom, pivotally mounted about a generally horizontal axis relative to a chassis of the machine. A further arm, known as a dipper, may be attached to an end of the boom remote from the chassis and may be pivotable about a generally horizontal axis. A material handling implement such as a bucket may be pivotably mounted on an end of the dipper. The boom may be raised and lowered by operation of a first hydraulic ram. The dipper may be moveable relative to the boom by operation of a second hydraulic ram, the bucket may be moveable relative to the dipper by operation of a third hydraulic ram. 
     Public utility systems may be run underground, as in the case of telephone lines, fiber optic cables, water mains, wastewater pipes and gas pipes, or above ground level, as in the case of electricity cables. Such cables and pipes may be damaged during operation of a material handling machine, for example when the bucket of a material handling machine is lowered to dig a trench it may penetrate or sever a cable or pipe, or when it is raised to move material from one location to another it might sever an overhead cable. This damage may result in disruption to the supply of a utility or service and the consequent expense of repairing or replacing the cable or pipe. In the case of damage to gas pipes, the result may be a catastrophic explosion, causing fatalities. 
     The risk of damage to high pressure gas pipes (for example pipes having a diameter of 1 meter) in the United Kingdom is reduced by continual aerial surveillance of pipelines. This requires helicopters to be flown along the length of pipelines and a pilot to monitor the use of excavators or the like in the vicinity of the pipelines. If a pilot sees an excavator or the like in operation in close proximity to a pipeline, the helicopter is landed and the operator of the machine is instructed to move out of the area. 
     BACKGROUND OF THE INVENTION 
     Accordingly, there is a need for an improved method for providing a warning. 
     Known systems enable data to be collected from material handling machines such as excavators, back hoe loaders (BHL), tele-handlers etc. in real time. Examples of the data that can be collected include the type of a machine, the location of the machine, the engine speed and the fuel levels of the machine. 
     This data is transmitted to a computer and processed by algorithms to provide information about one or more machines in a fleet, for example where a particular machine is or was located at any given time, the number of hours a machine has been working (or has been idle). 
     A user can also create and download reports from the website and register to receive notifications, for example that a machine has completed a number of working hours and should be serviced or that a machine appears to have a fault that should be investigated. These notifications are displayed within the website and so a user needs to log into the website to see them. A user may also register to receive these notifications via electronic mail. 
     The information about material handling machines can also be used to monitor the location of machines. Algorithms within a system compare the location of a machine with the co-ordinates of a geo-fence (that has been established to demarcate a site on which the machine is located) and, if the machine is moved outside the geo-fence a user is notified either via a notification on the secure website or via email, as described above. Alternatively a text message may be sent to the owner of a machine. 
     The information contained in the website, email and text notifications is restricted to information about the material handling machine itself. 
     According to an aspect of the present invention there is provided a computer-implemented method for providing a warning including the steps:
         obtaining data relating to the location of an object, obtaining data relating to the location of a material handling machine;   using the computer to compare the location of the material handling machine to the location of the object in order to estimate a probability of damage occurring; and   providing a warning based on the estimate.       

     The machine may be located remotely from the computer. 
     The machine may include the computer. 
     The warning may be received at a location remote from the computer and/or remote from the machine. 
     The warning may be received at the machine. 
     The machine may include the computer and the warning may be received at the machine. 
     The location of the object may be below ground level. The location of the object may be above ground level. 
     The method may further include obtaining data relating to the distance of the object below or above the ground level and using this data to estimate the probability of damage occurring. 
     The method may further include using a communication system. 
     The communication system may communicate the data relating to the location of the object to the computer. 
     The communication system may communicate the data relating to the location of the material handling machine to the computer. 
     The communication system may communicate the warning. 
     The communication system may communicate the warning to and/or from the material handling machine. 
     The material handling machine may be an excavator, or a backhoe loader, or a tele-handler. 
     The material handling machine may have a material handling implement, for example a ground-engaging material handling implement. 
     The method may further include determining the position of the material handling implement relative to the rest of the material handling machine, preferably the height of the material handling implement relative to the rest of the material handling machine, and using this data to estimate the probability of the damage occurring. 
     The method may further include determining if the material handling machine is moving, preferably the speed and/or direction at which the material handling machine is moving, and using this data to estimate the probability of the damage occurring. 
     The method may further include determining the type of the material handling machine, and using this data to estimate the probability of the damage occurring. 
     The material handling machine may have an engine and the method may include determining if the engine is running, preferably the speed at which the engine is running, and using this data to estimate the probability of the damage occurring. 
     The material handling machine may have a hydraulic system that manoeuvers the material handling implement and the method may include determining the pressure in the hydraulic system and using this data to estimate the probability of the damage occurring. 
     The warning may include an alarm, for example an audible, visual or vibration alarm. 
     The warning may include sending a message containing data about the estimate of the probability of damage occurring to and/or from the material handling machine. 
     According to an aspect of the present invention there is provided a material handling machine including a processor that is configured to receive data relating to the location of an object and data relating to the location of the material handling machine; to compare the location of the material handling machine and the location of the object; to estimate a probability of damage occurring; and to provide a warning based on the estimate. 
     According to an aspect of the present invention there is provided a system for providing a warning including a processor that is configured to receive data relating to the location of an object and data relating to the location of a material handling machine; to compare the location of the material handling machine and the location of 
     the object; to estimate a probability of damage occurring, and to provide a warning based on the estimate. 
     According to an aspect of the present invention there is provided a computer program product which when executed on a processor causes the processor to execute the steps of:
         comparing data relating to the location of an object and data relating to the location of a material handling machine;   estimating the probability of damage occurring; and   providing a warning based on the estimate.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described, by way of example only, with reference to the accompanying drawings in which: 
         FIG. 1  is a schematic side view of a material handling machine for use in a method according to the present invention, 
         FIG. 2  is a schematic view of part of the material handling machine of  FIG. 1 , 
         FIG. 3  shows a system architecture for implementing a method according to a first embodiment of the present invention, 
         FIG. 4  shows a system architecture for implementing a method according to a second embodiment of the present invention, and 
         FIG. 5  is a schematic view of part of an alternative material handling machine for use in a method according to the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     With reference to  FIGS. 1 and 2  there is shown a material handling machine  10  which in this example is an excavator including a chassis  12  and an operator cab  14 . The operator cab  14  is mounted on the chassis  12 . Ground engaging transport means in the form of a pair of tracks  16  are provided to move the machine over the ground. 
     Attached to the chassis is an arm assembly  18  (also known as an implement support system), the arm assembly includes a first arm in the form of a boom  20 , a second arm in the form of a dipper  22  and a ground engaging implement in the form of a bucket  24 . The boom  20  is pivotally mounted by pivot  26  to link  12 A at a first end  20 A of the boom. Link  12 A is pivotally mounted at a generally vertical axis relative to the chassis  12 . Pivot  26  is orientated horizontally. The dipper is pivotally mounted via pivot  28  to a second end  20 B of the boom  20 . Pivot  28  is orientated horizontally. The bucket is pivotally mounted via pivot  30  to an end  22 B of dipper  22  remote from end  22 A of dipper  22 . Pivot  30  is orientated horizontally. 
     A first hydraulic actuator in the form of a first hydraulic ram  32  has a first end  32 A pivotally attached to the chassis  12  and a second end  32 B pivotally attached to the boom part way between the first and second ends of the boom. A second hydraulic actuator in the form of a second hydraulic ram  34  has a first end  34 A pivotally attached to the boom part way between the first and second ends of the boom and a second end  34 B pivotally attached to the dipper proximate the first end  22 A of the dipper. A third hydraulic actuator in the form of a third hydraulic ram  36  has a first end  36 A pivotally attached to the dipper proximate the first end  22 A of the dipper and a second end  36 B pivotally attached to a linkage mechanism  38  proximate the second end of the dipper. The linkage mechanism  38  per se is known and simply converts extension and retraction movement of the third hydraulic ram  36  into rotary movement of the bucket  24  about pivot  30 . 
     Extension of the first hydraulic ram causes the boom to raise, and contraction of the first hydraulic ram causes lowering of the boom. Extension of the second ram causes the dipper to pivot in a clockwise direction (when viewing  FIG. 1 ) about pivot  28 , i.e. causes the boom to move in a “dipper in” direction, and retraction of the second hydraulic ram  34  causes the dipper to move in an anticlockwise direction when viewing  FIG. 1  about pivot  28 , i.e. in a “dipper out” direction. Extension of the third hydraulic ram  36  causes the bucket  24  to move in a clockwise direction about pivot  30 , i.e. in a “crowd” direction, and retraction of the third hydraulic ram  36  causes the bucket to move in an anticlockwise direction about pivot  30 , i.e. in a “dump” direction. 
     The first, second and third hydraulic rams are all double acting hydraulic rams. Double acting hydraulic rams are known per se. They include a piston within a cylinder. The piston is attached to a rod which extends beyond the end of the cylinder. The end of the rod remote from the piston defines one end of the hydraulic ram. The end of the cylinder remote from the rod defines an opposite end of hydraulic ram. A “head side chamber” is defined between the piston and the end of the cylinder remote from the rod. A “rod side chamber” is defined between the piston and the end of the cylinder proximate the end of the rod. Pressurization of the head side pressure chamber extends the ram and pressurization of the rod side chamber causes the ram to retract. 
     The machine includes a system for operating the first, second and third hydraulic rams, as described below. 
     A hydraulic pump  40  driven by a prime mover  41 . Prime mover  41  may be an internal combustion engine, though other prime movers are suitable. A boom spool valve  44  can be operated by an operator manipulating boom control  46 . In this case boom control  46  is a joystick. A dipper spool  48  valve can be controlled via a dipper control  50 . In this case dipper control  50  is a joystick. An implement spool valve  54  can be operated by an operator manipulating implement control  56 . In this case implement control  56  is a joystick. Joysticks  50 ,  46  and  54  may be separate joysticks (as shown in  FIG. 2 ). Alternatively two of the dipper control, implement control and boom control may be combined in a single joystick. Alternatively all three of the dipper control, boom control and implement control may be combined in a single joystick. Controls other than joysticks may be used to control one or more of the dipper spool, the boom spool or the implement spool. 
     The machine is positioned on the ground  2  and is operating near an underground pipeline  4  and near overhead cables  8  supported via poles or pylons  6 . 
     Operation of a material handling machine is as follows: 
     The prime mover  41  drives the hydraulic pump  40  which takes hydraulic fluid from tank T and pressurizes hydraulic line L 1 . As shown in  FIG. 2  the dipper spool valve is closed the implement spool valve  54  is closed and the boom spool valve is closed and hence pressurized fluid in line L 1  will pass through the relief valve  51  back to tank T. 
     If it is desired to raise the boom the boom control  46  is operated such that the boom spool  44 A of the boom spool valve  44  is moved so as to connect hydraulic line L 1  and L 2 . This causes hydraulic fluid to pass into the head side pressure chamber of the first hydraulic ram thereby extending the hydraulic ram and raising the boom. Hydraulic fluid from the rod side chamber passes into hydraulic line L 3  and back to tank T via the boom spool valve  44 . In order to lower the boom the boom control  46  is operated to move the boom spool  44 A in the opposite direction thereby connecting hydraulic line L 1  with L 3  and hydraulic line L 2  with tank T. 
     In order to move the dipper in a “dipper in” direction the dipper control  50  is operated such that the dipper spool  48 A of the dipper spool valve  48  connects line L 1  with hydraulic line L 4 . Hydraulic line L 4  is connected to the head side of the hydraulic ram  34  which causes the ram to extend thereby pivoting the dipper arm in a clockwise direction about pivot  28 . Hydraulic fluid in the rod side of hydraulic ram  34  passes into line L 5  and then on through the dipper spool valve  48  to tank T. In order to move the dipper in a “dipper out” direction the dipper control  50  is operated such that the dipper spool connects line L 1  with L 5  and connects line L 4  to tank. This results in retraction of the hydraulic ram  34  thereby causing the dipper to move in an anticlockwise direction about pivot  28 . 
     In order to move the bucket in a “crowd” direction the implement control  56  is operated such that the implement spool  54 A of the implement spool valve  54  connects line L 1  with hydraulic line L 6 . Hydraulic line L 6  is connected to the head side of the hydraulic ram  36  which causes the ram to extend thereby pivoting the implement in a clockwise direction about pivot  30 . Hydraulic fluid in the rod side of hydraulic ram  36  passes into line L 7  and then on through the implement spool valve  54  to tank T. In order to move the bucket in a “dump” direction the implement control  56  is operated such that the implement spool  54 A connects line L 1  with L 7  and connects line L 6  to tank. This results in retraction of the hydraulic ram  36  thereby causing the bucket to move in an anticlockwise direction about pivot  30 . 
     When digging a trench or the like a typical sequence of movements of the arm assembly is as follows: 
     Firstly, the boom is lowered and the dipper is moved in a “dipper out” direction thereby moving the bucket teeth  25  of the bucket  24  away from the chassis  12 . The boom is then further lowered such that the bucket teeth  25  engage the ground. The bucket is then crowded slightly so as to start to move the bucket teeth through the ground. The dipper control  50 , boom control  46  and bucket control (not shown) are then simultaneously operated to progressively move the dipper in “dipper in” direction and to move the boom in a “boom raised” direction and to move the bucket in a “crowd” direction such that the bucket teeth move generally towards the chassis. As will be appreciated, skill is involved in simultaneously manipulating the dipper control  50  and the boom control  46  and the bucket control  56  to efficiently fill the bucket with ground material. Once the bucket is full, the boom is raised, the arm assembly is swung laterally relative to the machine and the ground material is then dumped by moving the bucket to a dumped position. The sequence is then repeated. 
     With reference to  FIG. 3  there is shown a system architecture for a method according to the present invention. The system  70  includes a computer  72 , a database  74 , a wide area network  80  (for example the internet) and the material handling machine  10 . 
     The computer  72  includes a processor. The computer  72  can generate a warning as will be described further below. 
     The database  74  includes information relating to the location of one or more objects. The object may be a utility service such as a telephone line, a fiber optic cable, a water main, a water waste pipe, or a gas pipe. Alternatively, the object may be electricity pylon cables, high pressure gas pipe, an oil pipe, or the like. Certain of these objects are hazardous objects, since if damaged a hazardous event may occur. Other of these objects (for example underground fiber optic cables), are not hazardous, in as much as the damage to a fiber optic cable does not create a hazard for people in the immediate vicinity, rather it produces inconvenience for people attempting to use the cable and incurs a cost for the repair of the cable. 
     The wide area network  80  provides a backbone for communication within the system  70 . 
     The material handling machine  10  includes a monitoring unit  82  that collects data from the machine  10 , including the type of the machine  10 , the location of the machine  10 , the engine speed of the machine  10  and the pressure of oil in the hydraulic system of the machine  10 . The monitoring unit  82  includes a Global Navigation Satellite System (GNSS), for example a Global Positioning System (GPS) tracking unit. The GPS tracking unit enables the precise location of the machine  10  to be determined. 
     The monitoring unit  82  is connected to the computer  72  via the wide area network  80 . 
     The database  74  is connected to the computer  72  via the wide area network  80 . 
     Operation of the system  70  is as follows: 
     The monitoring unit  82  transmits information relating to the type of the machine  10 , the precise location of the machine  10 , the engine speed of the machine  10  and the pressure of oil in the hydraulic system of the machine  10  from the machine  10  to the computer  72  via the wide area network  80 . 
     The processor within the computer  72  uses one or more algorithms to determine further information about the machine. 
     The computer  72  receives information relating to the location of one or more objects from database  74 . 
     The computer  72  can then compare information relating to the machine with information relating to the location of one or more objects and can then make an estimation of probability of the machine damaging the object and issue a warning based on such an estimate. 
     EXAMPLE 1 
     The computer  72  receives information from the database  74  concerning an object, in this case an underground gas pipeline  4 . The position of the pipeline is communicated to computer  72  together with its depth below ground, in this example two meters below ground. 
     The computer  72  receives information from machine  10  concerning the machine type, the machine position, the engine speed of the machine and the pressure in the hydraulic circuit of the machine. Some of this information is periodically updated, in particular the position of the machine, the engine speed and the hydraulic circuit pressure. Period updates of this information are transmitted to the computer  72  once per second, though information update can be more frequent or less frequent than this. 
     The computer  72  can determine the type of machine and therefore can determine that the machine  10  is an excavator. In particular the computer  72  can determine that this type of excavator has a working arm that can reach three meters below ground. Thus, the computer  72  can determine that machine  10  is capable of digging a hole deep enough for the bucket  24  to strike the pipeline  4 . 
     Computer  72  can determine that the machine  10  is located near the pipeline. Because the information relating to the position of the machine is periodically updated, the computer can determine whether or not the machine is moving over the ground. In this case the machine is stationary, i.e. it is not moving over the ground. 
     The computer  72  can determine that the engine of the machine  10  is running and that the engine speed is relatively high. Due to the periodic updates the computer can determine whether the engine speed changes with time, in this example the engine speed is relatively high and stays at that relatively high level for a period of time. 
     Due to the periodic updates the computer can monitor the hydraulic pressure and determine how it changes with time. In this case the oil pressure in the hydraulic system is being varied with time. 
     The computer uses an algorithm to process this data to determine that the excavator is digging the ground since an excavator which is stationary with an engine speed that is relatively high and relatively constant and with an oil pressure in the hydraulic system which is varying with time is indicative of the excavator digging the ground. 
     Accordingly, the computer  72  can determine that the machine  10  is digging ground near the pipeline  4 . Whilst computer  72  cannot determine the depth below ground that the bucket of the machine  10  is working at, nevertheless because the bucket of machine  10  can reach down to a depth (3 meters) that is deeper than the depth of the pipeline (2 meters) there is a raised probability that damage to the pipeline from the bucket of the excavator might occur. Under these circumstances the computer  72  issues a warning to the operator  76  in charge of the pipeline. The operator  76  can then instruct someone to travel to the location of the machine  10  (either by helicopter or car etc.) to instruct the operator of the machine  10  to stop digging in that area. 
     EXAMPLE 2 
     With reference to  FIG. 5  there is shown a material handling machine  110  including a chassis  112 , an operator cab  114 . Attached to the chassis is an arm assembly  118  which includes a first arm in the form of a boom  120 , a second arm in the form of a dipper  122  and a ground engaging implement in the form of a bucket  124 . Machine  110  also includes a front loader arm  190  which includes a shovel  192 . 
     As will be appreciated the machine  110  is a back hoe loader (BHL). Operation of the arm assembly  118  (known as the back hoe) is similar to operation of the arm assembly  18  of machine  10 . Operation of the front loader arm  190  and shovel  192  is well known in the art, but in summary hydraulic rams are able to lift and lower the front loader arm  191  and further hydraulic rams are able to “crowd” or “dump” shovel  192  relative to the front loader arm  190 . 
     The back hoe loader  110  includes a monitoring unit  181 . 
     In this example the back hoe loader  110  replaces the machine  10  (as indicated by the chain dotted lines of  FIG. 3 ) when considering  FIG. 3 . 
     EXAMPLE 2a 
     The computer  72  receives information from the database  74  concerning an object, in this case, an underground gas pipeline  4  positioned 2 meters below the ground. Computer  72  receives information from the machine indicating that the machine has a back hoe capable of reaching 3 meters below ground level, the back hoe loader is stationary with an engine speed that is relatively high and relatively constant and with an oil pressure and hydraulic system which is varying with time. 
     The computer can therefore determine that the back hoe loader is being used to dig ground with the back hoe. 
     The computer can determine that the maximum depth of back hoe (3 meters) is lower than the depth of the gas pipeline (2 meters). The computer can determine that the back hoe loader is being operated in the vicinity of the pipeline. Accordingly, there is a raised probability that damage to the pipeline from the bucket of the back hoe loader might occur. Under these circumstances the computer  72  issues a warning to the operator  76  in charge of the pipeline. Operator  76  can then instruct someone to travel to the location of the back hoe loader (either by helicopter or car etc.) to instruct the operator of the back hoe loader to stop digging that area. 
     EXAMPLE 2b 
     The computer  72  receives information from the database  74  concerning an object, in this case an underground gas pipeline  4  positioned 2 meters below ground. The computer receives information from the back hoe loader  110 . In this case the back hoe loader is moving backwards and forwards relatively short distances (for example 20 meters). The engine speed is varying. Oil pressure within the hydraulic system is varying. The computer  72  uses an algorithm to determine that this indicative of the back hoe loader being used to load material via the shovel  192 . Typically shovels  192  load material from ground level, but are not used to dig into the ground. Accordingly, whilst the machine may be in the vicinity of the gas pipeline, because the front loader arm and shovel are being used (and the backhoe is not being used), then the likelihood of damage occurring to the pipeline positioned 2 meters below ground level is low and hence no warning need be issued. 
     EXAMPLE 2c 
     The computer  72  receives information from the database  74  concerning an object, in this case an underground gas pipeline  4  positioned 2 meters below ground. The computer  72  receives information from the back hoe loader  110 . The computer determines that the back hoe loader  110  is moving at 30 mph, along a generally straight path. The engine speed is relatively high and relatively constant. The oil pressure in the hydraulic system is low and not varying with time. The computer  72  uses an algorithm to determine from this information that the back hoe loader is “roading” i.e. being driven from one site or location to another site or location. Whilst the back hoe loader  110  may remain in close proximity to the gas pipeline during “roading” (for example where the backhoe loader is being driven along a road which lies close to and parallel to the gas pipeline  4 ), nevertheless the computer  72  can determine that the likelihood of damage being done to the pipeline is low (since the backhoe is not being used) and hence no warning need be issued. 
     EXAMPLE 2d 
     Computer  72  receives the information from the database  74  concerning an object, in this case an underground gas pipe  4  positioned 2 meters below the ground. 
     The computer  72  receives information from the back hoe loader  110 . In this case the back hoe loader is travelling at 50 mph along a generally straight path. The engine speed is 0 rpm, the oil pressure within the hydraulics system is 0 psi. Accordingly, the computer  72  can determine that the back hoe loader  110  is being transported on a transporter (e.g. lorry or the like) from one location to another location. In particular the maximum speed of the back hoe loader is 30 mph and hence the computer  72  can determine that the backhoe loader is not travelling under its own power. The computer  72  determines that the likelihood of damage to the pipeline is low and accordingly no warning is issued. 
     In the examples above, the computer  72  is positioned remotely from the machine. In one example the computer  72  is under the control of the manufacturer of the machine  10  and  110 . The operator  76  may be located remotely from machine  10 / 110  and also remotely from the manufacturer of machines  10 / 110 . In one example the operator  76  will be a utility company. 
     The database  74  may be controlled by the utility company since it is the utility company that has the ability to update the database  74  as and when further pipelines are laid, or when existing pipelines become inactive. 
     In summary, in the examples above, computer  72  (under the control of the machine manufacturer) receives information from the machine  10 / 110  and database  74  and, in the event of a likelihood of damage occurring a warning is provided to the utility operator  76 . It is the utility operator  76  which then takes action to halt operation of the machine  10 / 110 . 
     In a further example the warning can be directly issued to the operator of the machine  10 / 110 . Thus, as shown in  FIG. 4  the machine  10 / 110  includes a computer  172 . Computer  172  receives the information from database  174  via a wide area network (for example the internet). Computer  172  also receives information from the monitoring unit  82 / 182 . In the event of a likelihood of damage occurring computer  172  issues a warning to the machine operator  176 . The warning may be in the form of an audible, visual or vibratory alarm. In particular the warning may include a message relating to the object, for example a message such as “warning pipeline below machine” may be presented on a screen or the like indicating to the machine operator the nature of a hazard. 
     As mentioned above, the machine  10  is an excavator and machine  110  is a backhoe loader, though the invention is equally applicable to other types of material handling machines, for example tele-handlers. 
     As mentioned above, communication system  80  is wide area network, though other types of communication system could be used. 
     As mentioned above, the warning is issued to operator  76  or to operator  176 . In further embodiments multiple warnings could be issued, for example a warning could be issued to both a utility company or the like and the machine operator. 
     In the examples above the objects to which damage might be caused are all below ground. However, the objects may be above ground, for example overhead cables  8  mounted on poles or pylons  6 . Whilst the overhead cables  8  are visible to the operator of the machine, nevertheless when the operator is concentrating on digging a trench or the like it is easy for the operator to forget that the cables  8  are near and accordingly it is sometimes possible to damage cables  8  when swinging the bucket  24 / 124  to dump some spoil. A system can be used to warn of possible damage to overhead cables or the like. In particular if the overhead cables are six meters above ground and the maximum reach of the bucket  24 / 124  above ground is only 3 meters, then it is not necessary to issue a warning. However, if the bucket can reach high enough to damage the cables than a warning may be sent, in particular a warning to the machine operator may be presented on the screen or the like such as “warning—overhead cables”. This may act to remind the operator of the cables. 
     As mentioned above, monitoring unit  82  that collects data from the machine  10  includes data relating to the type of machine, the location of the machine, the engine speed of the machine and the pressure of oil in the hydraulic system of the machine. Further embodiments more data can be collected or less data can be collected. In particular in order to determine what he machine is doing it is not necessary to monitor hydraulic oil pressure. Other ways of determining what the machine is doing can be used, for example switches or the like can determine what the machine is being used for, and/or the engine torque can be used to determine what the machine is being used for. 
     As described above the example of the Global Navigation Satellite System was GPS. Other Global Navigation Satellite Systems could be used, for example GLONASS or Galileo. Alternatively, a regional navigation system could be used. 
     In the examples described above, the material handling machines  10 ,  100  included arm assemblies  18 ,  118  having first arms  20 ,  120  and second arms  22 ,  122 . In alternative embodiments of the invention, the material handling machine may include an arm assembly having a single arm. In some embodiments, the single arm may extend and retract telescopically. 
     In the examples described above, the arm assemblies  18 ,  118  include ground engaging implements in the form of buckets  24 ,  124 . It will be understood that in alternative embodiments of the invention, the arm assembly may include any ground engaging or ground moving implement, for example a bucket, a shovel, a fork, a tine or a hydraulic hammer. It will also be understood that the arm assembly may include an implement that moves ground from one above-ground position to another above-ground position, for example a bucket, a shovel, a fork, a tine or a platform. In some embodiments, the implement may be telescopically mounted on the arm assembly. 
     In the examples described above, the arms assemblies  18 ,  118  are backhoes. In alternative embodiments of the invention, the arm assembly may be a front loader arm assembly or a tele-handler arm assembly, in particular a telescopic tele-handler arm assembly. 
     In Example 1 described above, the computer monitors the hydraulic pressure and determines how it changes with time. In alternative embodiments, the computer may monitor in which components of the machine the hydraulic pressure is changing.