AU2016200780B1 - Mining machine - Google Patents

Abstract

This disclosure relates to a mining machine and method. The mining machine comprises a shearing head mounted on a carriage on a rail, roof supports and an at least 2D position determining system. The mining machine further comprises a processor to receive the absolute position signals, to determine during a first traversal a distance by which to move one of the roof supports, to determine during the first traversal that the moveable carriage has passed the roof support; and to generate a control signal for a moving element connected to the roof support to move during the first traversal the roof support by the distance determined during the first traversal such that when the moving element connected to the one of the multiple roof supports moves the rail, the rail assumes the desired profile.

Description

1 Mining machine Cross-Reference to Related Applications The present application claims priority from Australian Provisional Patent Application 5 No 2015901986 filed on 28 May 2015, the content of which is incorporated herein by reference. Technical Field This disclosure relates to a mining machine and method whereby a mining machine can 10 be controlled to move across a seam containing product to be mined, for example, but not limited to, the longwall mining of coal. Background Art In the mining of coal, processes have been developed which are referred to as longwall 15 mining processes. In these processes a moveable rail is placed to span across a coal seam. A mining machine is provided with a shearing head and the mining machine is moved to traverse along the rail from side-to-side of the seam, and the shearing head is manipulated upwardly and downwardly to remove further coal from the seam. The process is repeated until all coal in the planned extraction panel is completed. Thus, by 20 advancing the rail forwardly towards the seam by a suitable distance after each pass, it is possible to progressively move into the seam with an approximate equal depth of cut with each pass. In practice, inaccuracies develop with each subsequent pass due to slippage of a 25 powered roof support advance system which moves the rail, resulting in the depth of cut varying across the face of the seam. This, in turn, leads to reduced production yields and unnecessary mechanical loading and stresses on the rail and powered roof support advance system. Such inaccuracies are attributable, in large part to the fact that the powered roof support advance system moves the rail forwardly by a set incremental 30 amount at each pass. Thus, because of the slippage of the powered roof support advance system, the inaccuracies accumulate after many passes of the machine. The rail is expected to follow the desired profile which in some examples extends in a 2 straight line, but, because of the slippage, the rail is progressively moved so that it eventually has a curvilinear path. This, in turn, results in down time in attempting to reposition the rail to correct these accumulated inaccuracies. 5 Many systems have been developed for repositioning and maintaining the rail on the desired profile across the face of the seam. Simple systems use a string line. Other systems use optical means which produce light beams which reflect off reflectors strategically placed at the sides of the seams. Radar systems have also been proposed. None have proved satisfactory as they each require time to set-up, and manual 10 adjustment of some or all of the support powered roof supports. In addition to the above, a coal seam follows contours and folds in the strata structure and therefore the coal seam is not a predictable shape. This, in turn, has led to difficulties in causing the shearing head to accurately follow the seam on a predictable 15 basis at each pass. If the shearing head attempts to shear past the coal seam boundary into the much harder roof and floor stone material this produces unnecessary and undesirable loadings on the drive motors of the shearing head and results in inefficient yields and production dilution. 20 It is therefore desirable to know the absolute co-ordinate position of the mining machine at sufficient points across the face of the seam for each successive shear so that the vertical contour (i.e. horizon) can be predicted and the vertical up and down movement of the shearing head can be controlled and dynamically adjusted to cause the mining machine to follow the undulating coal seam (horizon control). Existing 25 methods of horizon control include a reactive method based on detecting and reacting to the increased load on the cutting drum motors when the shearing head is raised or lowered beyond the coal seam. This reactive technique results in mechanical stress and product dilution due to the inclusion of non-coal material. Another method referred to as "mimic cut" uses sensors to record the vertical limits of the shearer head under 30 manual control throughout a complete pass across the longwall face. The system then attempts to automatically replicate this shearing pattern through a next pass. This 3 approach does not take into account the undulation in the seam in the direction of longwall progression. Radar and natural gamma sensors have also been proposed as a means of detecting the coal seam boundary. However, these systems are not always suitable and in any case require human intervention. 5 Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of 10 each claim of this application. Throughout this specification the word "comprise", or variations such as "comprises" or 'comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, 15 integer or step, or group of elements, integers or steps. Disclosure of Invention There is provided a mining machine comprising: a shearing head mounted on a moveable carriage, said shearing head being for 20 mining product from a seam as said moveable carriage traverses from side-to-side across a mining face of said seam on a rail which extends from side-to-side across the seam; multiple roof supports to support a mine roof after mining the product from the seam, each of the multiple roof supports being connected to the rail by a respective 25 moving element; an at least 2D co-ordinate position determining system to determine an absolute co-ordinate position in space of the moveable carriage at one or more locations along the rail during a first traversal, each of the one or more locations being associated with one of the multiple roof supports, said position determining system providing absolute 30 co-ordinate position output data signals therefrom; a processor 4 to receive the absolute co-ordinate position output data signals, to determine during the first traversal of the moveable carriage a distance by which to move the one of the multiple roof supports towards the seam based on the absolute co-ordinate position determined during the first traversal and 5 based on a desired profile; to determine during the first traversal that the moveable carriage has passed the one of the multiple roof supports; and upon determining during the first traversal that the moveable carriage has passed the one of the multiple roof supports, to generate a control signal for the 10 moving element connected to the one of the multiple roof supports to move during the first traversal the one of the multiple roof supports by the distance determined during the first traversal such that when the moving element connected to the one of the multiple roof supports moves the rail, the rail assumes the desired profile. In most longwall mining situations, the roof supports are moved forward immediately 15 after the shearing head has passed them to prevent the collapse of the roof onto the rail. Further, the advancing distance of the roof supports defines the location of the rail. However, the required distances are calculated for the entire rail at once when the shearing head reaches the end of the seam. This means that the distances can only be applied in the next traversal which introduces inaccuracies. Instead, the processor 20 above calculates and applies the distances in real-time, that is, in the same traversal. This means that the immediate advancement of the roof support is based on most up-to date position of the track. As a result, it is an advantage of the mining machine that the correction of the rail is more accurate and resembles the desired profile more closely than with existing mining machines. 25 In one example, each of the multiple roof supports has an engaged state where that roof support is engaged with the mine roof such that the roof support provides a fixed position for the moving element to move the rail, each of the multiple roof supports has a disengaged state where the roof support is moveable by the moving element while the rail provides a fixed position for the 30 moving element to move that roof support, 5 and to generate the control signal comprises to generate the control signal for the one of the multiple roof supports to assume the disengaged state during the first traversal when moving the one of the multiple roof supports by the distance determined during the first traversal and to assume the engaged state when moving the rail during 5 the first traversal to assume the desired profile for the second traversal. The moving element connected to the one of the multiple roof supports may move the rail by a predefined distance that is independent of the absolute co-ordinate position. The at least 2D co-ordinate position determining system may be located in any suitable 10 position from which it is able to determine an absolute co-ordinate position in space of the moveable carriage at one or more locations along the rail. Preferably, the 2D co ordinate position determining system is located on the mining machine, rail or roof support structure. More preferably, the the 2D co-ordinate position determining system is located on the moveable carriage. 15 The processor preferably has a subterranean location, preferably between a main and tail gateroad that the moveable carriage is traversing. More preferably the processor is located within 10 metres from the mining machine. Wireless communications between the processor and the mining machine become more effective when the processor and 20 mining machine are within close proximity. The mining machine may further comprise a cable to connect the co-ordinate position determining system to the processor. The processor may be mounted to the mining machine. 25 It is an advantage that no data connection to above ground computers is required. This reduces the cost for cables and also reduces the risk of cables being cut by mining operations. Further, the proximity of the mining machine and processor results in a higher bandwidth. As a result, more measurements can be provided to the processor to determine a more accurate advancement distance.

6 The processor may be mounted to the moveable carriage. The one or more locations associated with one of the multiple roof supports may comprise more than 5 locations associated with one of the multiple roof supports such 5 that determining the distance is based on more than 5 locations. The one or more locations associated with one of the multiple roof supports may comprise more than 100 locations associated with one of the multiple roof supports such that determining the distance is based on more than 100 locations. 10 The one or more locations associated with one of the multiple roof supports may comprise between 5 and 2000 locations associated with one of the multiple roof supports such that determining the distance is based on between 5 and 2000 locations. 15 The position determining system may comprise a first odometer and a second odometer and a first resolution of distance measurements of the first odometer is less than a second resolution of distance measurements of the second odometer. The first (low resolution) odometer has a resolution of less than 10 distance 20 measurements per metre and the second odometer (high resolution) has a resolution of more than 100 distance measurements per metre. The second odometer preferably has a resolution of at least 500 distance measurements per meter and more preferably at least 1000 distance measurement per meter. 25 The first odometer may provide absolute distance measurements and the second odometer may provide incremental distance measurements. The first odometer may provide absolute distance measurements and the second odometer may provide absolute distance measurements.

7 In one embodiment, there is only provided the high resolution odometer (i.e. more than 100 distance measurements per metre). Within this embodiment, the odometer may provide incremental distance measurements and absolute distance measurements. 5 The position determining system may determine an attitude angle associated with each distance measurement and may determine the absolute co-ordinate position based on the distance measurements and the associated attitude angles. It is an advantage that with more odometer readings that are associated with attitude angles, the determined absolute position is more accurate and therefore, the position of 10 the rail is closer to the desired profile than when using only a single low resolution odometer. There is also provided a method for controlling a mining machine, the mining machine comprising: a shearing head mounted on a moveable carriage, said shearing head being for 15 mining product from a seam as said moveable carriage traverses from side-to-side across a mining face of said seam on a rail which extends from side-to-side across the seam; and multiple roof supports to support a mine roof after mining the product from the seam, each of the multiple roof supports being connected to the rail by a respective 20 moving element; the method comprising: receiving absolute co-ordinate position output data signals from an at least 2D co-ordinate position determining system for determining an absolute co-ordinate position in space of the moveable carriage at one or more locations along the rail during 25 a first traversal, each of the one or more locations being associated with one of the multiple roof supports, said position determining system, determining during the first traversal of the moveable carriage a distance by which to move the one of the multiple roof supports towards the seam based on the absolute co-ordinate position determined during the first traversal and based on a 30 desired profile; 8 determining during the first traversal that the moveable carriage has passed the one of the multiple roof supports; and upon determining during the first traversal that the moveable carriage has passed the one of the multiple roof supports, generating a control signal for the moving 5 element connected to the one of the multiple roof supports to move during the first traversal the one of the multiple roof supports by the distance determined during the first traversal such that when the moving element connected to the one of the multiple roof supports moves the rail, the rail assumes the desired profile for the second traversal. 10 Generating the control signal for the moving element may comprise generating the control signal such that when the moving element connected to the one of the multiple roof supports moves the rail, the rail assumes the desired profile for a second traversal immediately after the first traversal. Generating the control signal for the moving element may comprise generating the 15 control signal such that when the moving element connected to the one of the multiple roof supports moves the rail, the rail assumes the desired profile for a remainder of the first traversal. Generating the control signal may be performed before determining that the moveable carriage has passed any subsequent roof support of the multiple roof supports. 20 Determining the distance by which to move the one of the multiple roof supports towards the seam may comprise determining the distance based on the absolute co ordinate position at one or more selected locations associated with the one of the multiple roof supports and independent of the absolute co-ordinate position at locations associated with the one of the multiple roof supports other than the selected locations. 25 Software that, when executed by a computer, causes the computer to perform the method described above.

9 According to one aspect, there is provided a mining machine comprising: two or more shearings heads each mounted upon an arm connected via a rotatable joint to a moveable carriage, said shearing head being for mining product from a seam as said moveable carriage traverses from side-to-side across a mining face 5 of said seam on a rail which extends from side-to-side across the seam; and multiple roof supports to support a mine roof after mining the product from the seam, each of the multiple roof supports being connected to the rail by a respective moving element; characterised in that the mining machine further comprises: an at least 2D co-ordinate position determining system to determine an absolute 10 co-ordinate position in space of the moveable carriage at one or more locations along the rail during a first traversal, each of the one or more locations being associated with one of the multiple roof supports, said position determining system providing absolute co-ordinate position output data signals therefrom; and a processor comprising: 15 an absolute co-ordinate position output data signals receiving unit receiving the absolute co-ordinate position output data signals from said position determining system, a distance determining unit determining during the first traversal of the moveable carriage a distance by which to move the one of the multiple roof supports 20 towards the seam based on the received absolute co-ordinate position output data signals and based on a desired profile; a passing determining unit determining during the first traversal that the moveable carriage has passed the one of the multiple roof supports; and a control signal generating unit, upon the passing determining unit 25 determining during the first traversal that the moveable carriage has passed the one of the multiple roof supports, generating a control signal for the moving element connected to the one of the multiple roof supports to move during the first traversal the one of the multiple roof supports by the distance determined by the distance determining unit such that when the moving element connected to the one of the 30 multiple roof supports moves the rail, the rail assumes the desired profile.

10 In an embodiment, each of the multiple roof supports has an engaged state where that roof support is engaged with the mine roof such that the roof support provides a fixed position for the moving element to move the rail, and each of the multiple roof supports has a disengaged state where the roof support is moveable by the moving element while 5 the rail provides a fixed position for the moving element to move that roof support. In an embodiment, the moving element connected to the one of the multiple roof supports moves the rail by a predefined distance that is independent of the absolute co ordinate position. 10 In an embodiment, the processor is located within 10 metres from the mining machine. In an embodiment, the mining machine comprises a cable to connect the co-ordinate position determining system to the processor. 15 In an embodiment, the processor is mounted to the mining machine. In an embodiment, the processor is mounted to the moveable carriage. 20 In an embodiment, the one or more locations associated with one of the multiple roof supports comprises more than 5 locations associated with one of the multiple roof supports such that the distance is determined based on more than 5 locations. In an embodiment, the one or more locations associated with one of the multiple roof 25 supports comprises more than 100 locations associated with one of the multiple roof supports such that the distance is determined based on more than 100 locations. In an embodiment, the one or more locations associated with one of the multiple roof supports comprises between 5 and 2000 locations associated with one of the multiple 30 roof supports such that the distance is determined based on between 5 and 2000 locations.

11 In an embodiment, the position determining system comprises a first odometer and a second odometer and a first resolution of distance measurements of the first odometer is less than a second resolution of distance measurements of the second odometer, and the first odometer and the second odometer may comprise a quadrature encoder 5 connected to a shaft which is connected to a gearbox which is physically driven by an interaction with the travel mechanism. In an embodiment, the first odometer provides a quadrature pulse every 0.1 meter travel and the second odometer provides a quadrature pulse every 0.01 meter travel. 10 In an embodiment, the first odometer is to provide absolute distance measurements and the second odometer is to provide incremental distance measurements. In an embodiment, the first odometer is to provide absolute distance measurements and 15 the second odometer is to provide absolute distance measurements. In an embodiment, the position determining system is to determine an attitude angle associated with each distance measurement and is to determine the absolute co-ordinate position based on the distance measurements and the associated attitude angles. 20 Optional features described of the mining machine where appropriate, similarly apply to the method and software also described here. Brief Description of Drawings 25 An example will be described with reference to Fig. 1 illustrates a diagrammatic view of a coal seam showing the undulations therein and the relative change in elevation of the seam along its length. Fig. 2 illustrates a diagrammatic view showing the coal seam and a typical shearing machine during a traverse across the seam. 30 Fig. 3 illustrates a detailed close-up view showing the seam with a longwall mining machine.

12 Fig. 4 illustrates a computer system for controlling a mining machine. Fig. 5 illustrates a method for controlling a mining machine. Fig. 6 illustrates plan views in diagrammatic form showing a prior art mining machine during several passes. 5 Fig. 7 illustrates the roof supports in greater detail. Fig. 8 illustrates a plan view of an example of a mining machine during a traversal. Figs. 9a-c illustrate plan views of a series of traversals of a mining machine mining into a seam. 10 Figs. 9d-f illustrate diagrammatic views showing profiles and movements of the rail on which the mining machine moves. Fig. 9g illustrates the angle between a current position on the rail and a new position at two points. Fig. 10 illustrates the locations where the co-ordinate positions of the mining 15 machine may be determined. Fig. 11 illustrates a software flow diagram of the overall method of longwall mining. Best Mode 20 Referring firstly to Fig. 1 there is shown a seam 1 of coal relative to X, Y, and Z planes. Fig. 1 is diagrammatic and shows an upward inclination of the seam 1 together with folds and contours throughout the seam 1. The strata below and above the seam has not been shown. The seam 1 has a longwall face 3 and a vertical depth or thickness indicated by thickness 5. The depth or thickness 5 is typically, substantially uniform 25 throughout the whole of the seam 1. When mining the seam 1, a mining machine attempts to make a series of side-to-side cuts across the seam. Each cut is represented by the narrow line markings across the seam 1. In other words, the longwall face 3 is exposed progressively with each 30 succeeding side-to-side cut. It can be seen that as the side-to-side cuts progress in a directionally generally orthogonal to the longwall face 3 (i.e. in the Y direction) the 13 horizon aspect changes upwardly. This is merely exemplary as in other examples the horizon aspect may extend downwardly. In addition, the seam 1 is shown as having a generally horizontal aspect along the X axis. The seam may have an inclination along the X axis. In other words, Fig. 1 merely shows one possible type of seam 1 5 configuration. This change needs to be predicted to enhance efficiencies in the mining process. Referring now to Fig. 2 there is diagrammatically shown how a mining machine 7 carrying shearing heads 9 can move across the longwall face 3 of the seam 1. The 10 mining machine 7 therefore moves over the upper surface of strata 11 below the seam 1, and underneath the lower surface of strata 13 above the seam 1. As the machine progresses forwardly in the direction shown by arrow 15 after each side-to-side pass, it progressively mines the coal or other product in the seam 1. 15 Fig. 3 shows the arrangement of the mining machine 7 and seam 1 in close-up detail. The mining machine 7 comprises a shearing head 9 mounted on a moveable carriage 17. The shearing head 9 is used to mine the product from seam 1 as the moveable carriage 17 traverses from side-to-side across the mining face of seam 1. The moveable carriage 17 traverses on a rail 19 which extends from side-to-side across the seam 1. 20 Fig. 3 also shows multiple roof supports 23 which support strata mine roof of the underlying surface of the overlying strata 13. The roof supports 23 are positioned between the mine roof and the underlying strata 11 so as to support the mine roof 13 after mining the product from seam 1, each of the multiple roof supports being 25 connected to the rail 19 by a respective moving element 25. Each of the moving elements 25 is independently moveable. In Fig. 3, several of the roof supports 23 have purposely not been shown in order to clearly expose the mining machine 7. However, it should be understood that in practical use the multiple roof supports 23 extend along the length of the rail 19 at substantially equally spaced intervals. 30 14 An at least 2D co-ordinate position determining system 300 is carried by the moveable carriage 17. In one example the co-ordinate position determining system 300 is mounted on the moveable carriage 17 such as by permanent fixing of a housing of the co-ordinate position determining system 300, for example by welding. In other 5 examples the housing may be removably attached to the moveable carriage 17. The co ordinate position determining system 300 is able to determine an absolute co-ordinate position in space of the moveable carriage 17 at one or more locations (see 500 in Fig. 10) along the rail 19 during a first traversal. The absolute co-ordinate position may be at least two dimensions and is typically in the X and Y directions. Each of the one or 10 more locations 500 is associated with one of the multiple roof supports 23. The position determining system 300 provides an absolute co-ordinate position output data signal for a processor 102 of a computer system 100 to receive. Fig. 4 illustrates a computer system 100 which calculates the distance 27 for the 15 multiple roof supports 23 to advance in a mining machine configuration as illustrated in Fig. 3. The computer system 100 comprises a processor 102 connected to a program memory 104, a data memory 106, first data port 108 being an input port and second data port 110 being an output port. The first data port 108 and the second data port 110 may be the same data port. The processor is also connected to a user interface 112 that 20 interfaces the processor 102 with a display 114 operated by a decision maker 116. In one example the program memory 104 is a non-transitory computer readable medium, such as a hard drive, a solid-state disk or CD-ROM. Software, that is an executable program comprising computer executable instructions, 25 stored on program memory 104 causes the processor 102 to perform the method in Fig. 5, that is, the processor 102 determines a distance 27 for each of the multiple roof supports 23 to advance towards the mining face 3. The software stored on program memory 104 turns the computer system 100 into a practical calculator of distance 27 for the roof support 23 to advance. 30 15 It is to be understood that any kind of data port may be used to receive and send data, such as a network connection, a memory interface, a pin of the chip package of processor 102, or logical ports, such as IP sockets or parameters of functions stored on program memory 104 and executed by processor 102. The processor 102 may receive 5 data through all these interfaces, which includes memory access of volatile memory, such as cache or RAM, or non-volatile memory, such as an optical disk drive, hard disk drive, storage server or cloud storage. In one example the processor 102 receives position information as output data signals 10 from a position determining system 300 via a direct cable connection between the positioning determining system 300 and the input port 108, stores this information on data memory 106 and determines the distance 27 by which to move one of multiple roof supports 23 towards the mining face 3. The processor 102 stores the distances 27 on the data memory 106 and the processor 102 then requests the distances from the 15 memory 106 for later use. The processor 102 is able to repeat this process. Then, for example, the processor 102 requests the distances 27 from the memory 106 to process output signals for one of the multiple roof supports 23 to receive. The processor 102 then sends the determined output signal via communication port 108 to 20 one of the multiple roof supports 23, in this example, via a direct cable connection between the communication port 108 to the multiple roof supports 23. In a more general example, the processor 102 comprises an absolute co-ordinate position output data signals receiving unit, such as the input port 108, receiving the 25 absolute co-ordinate position output data signals from said position determining system 300; a distance determining unit determining during the first traversal of the moveable carriage 17 a distance by which to move the one of the multiple roof supports 23 towards the seam based on the received absolute co-ordinate position output data signals and based on a desired profile; a passing determining unit determining during 30 the first traversal that the moveable carriage 17 has passed the one of the multiple roof supports 23; and a control signal generating unit, upon the passing determining unit 16 determining during the first traversal that the moveable carriage 17 has passed the one of the multiple roof supports 23, generating a control signal for the moving element 25 connected to the one of the multiple roof supports 23 to move during the first traversal the one of the multiple roof supports 23 by the distance determined by the distance 5 determining unit such that when the moving element 25 connected to the one of the multiple roof supports 23 moves the rail 19, the rail 19 assumes the desired profile. In some examples, the processor 102 generates a graphical user interface 112, such as a view depicting the status of the multiple roof supports 23, and causes the graphical user 10 interface 112 to be displayed on display device 114 by sending appropriate commands and data to the display device 114. The decision maker 116 can view the user interface 112 and plan the control of the mining machine 7 accordingly. In one example, the processor 102 receives and processes the position information as 15 output data signals from a position determining system 300 in real-time. Real-time in this context means that the processor 102 determines the distance 27 by which to move one of multiple roof supports 23 towards the mining face 3 each time that the position information is received from the position determining system 300, and completes this calculation before the positioning determining system 300 sends the next position 20 information update. It is to be understood that throughout this disclosure unless stated otherwise, variables and models and the like refer to data structures, which are physically stored on data memory 106 or processed by processor 102. Further, for the sake of brevity when 25 reference is made to particular variable names, such as "co-ordinate position" or "distance" this is to be understood to refer to values of variables stored as physical data in computer system 100. Fig. 5 illustrates a method 200 for controlling a mining machine. Processor 102 30 performs method 200. In step 202, the processor 102 receives the absolute co-ordinate position output data signals from the 2D co-ordinate position determining system 300.

17 Step 204 determines during the first traversal of the moveable carriage 17 a distance 27 by which to move the one of the multiple roof supports 23 towards the seam 1. This distance 27 is based on the absolute co-ordinate position as received in step 202 and a desired profile of movement for the moveable carriage 17. 5 In step 206 the processor 102 determines during the first traversal that the moveable carriage 17 has passed one of the multiple roof supports 23. Upon determining from step 206 that the moveable carriage 17 has passed one of the multiple roof supports 23, processor 102 generates 208 a control signal for the moving element 25 connected to 10 one of the multiple roof supports 23 to move during the first traversal. The distance 27 the moving element 25 moves is such that when the moving element 25 moves the rail 19 by a predefined distance (see 404 of Fig. 7), the rail 19 assumes the desired profile. In one example, the method 200 is a reactive correction method such that rail 19 15 assumes the desired profile for the second traversal. In another example, the method is a predictive correction method such that rail 19 assumes the desired profile for the remainder of the first traversal. In this case, processor 102 determines an error between the desired profile and the measured positions for the locations of the first traversal that the carriage has passed and corrects the position of the rail in front of the carriage that 20 the carriage is about to pass in order to compensate for that error. While this error is an estimate, this forward error correction may result in a greater overall accuracy than without forward error correction. Forward and backward correction may be combined to further increase the accuracy of the rail positions. 25 Generating the control signal may be a single signal that is sent that includes the determined distance and the receipt of the control signal by the roof support 23 indicates that the movement by the moving element 25 should commence as soon as possible. Alternatively, the control signal may include determined distance and timing information of a future time based on which the moving element 25 should commence. 30 Further, the control signal could be separated into multiple messages.

18 Fig. 5 is to be understood as a blueprint for the mining machine software program and may be implemented step-by-step, such that each step in Fig. 5 is represented by a function in a programming language, such as C++ or Java. The resulting source code is then compiled and stored as computer executable instructions on program memory 104. 5 It is noted that for most humans performing the method 200 manually, that is, without the help of a computer, would be practically impossible. Therefore, the use of a computer is part of the substance of the disclosure and allows performing the necessary calculations that would otherwise not be possible due to the large amount of data and 10 the large number of calculations that are involved. In the prior art, as the mining machine 7 advances pass-by-pass into the seam 1, the roof supports 23 are individually released from supporting the mine roof and displace forwardly towards seam 1 immediately after the shearing head 9 has passed them to 15 prevent the collapse of the roof onto the rail 19. The advancing distance of the roof supports 23 defines the location of the rail 19. However, the advancing distances are calculated for the entire rail simultaneously when the shearing head 9 reaches the end of the seam. In this way, the distances calculated at the end of each traversal can only be applied to the next traversal. This introduces inaccuracies as the information used to 20 calculate the advancing distance is not the most up-to-date information. In contrast to the prior art, this disclosure reduces the inaccuracies by ensuring the most up-to-date co-ordinate position information is used in calculating the advancing distance in real time. 25 Fig. 6 illustrates a series of plan view diagrams which show a typical longwall mining process. Each of Figs. 6a - 6h is annotated to show various stages in the passing of the machine 7 across the mining face 3. Fig. 6h shows the extreme condition which occurs in the prior art where a curvilinear or snake path develops after many passes due to the inaccurate determination of the position of the rail and slippage of the roof supports as 30 the rail moves many times over many passes. The various systems used in the past for positioning the rail 19 and for controlling the mining machine 7 have resulted in 19 inefficiencies in mining techniques as discussed above. The present disclosure overcomes the difficulties of the prior art by determining the at least 2D co-ordinate position of the rail 19 during the first traversal, and then calculating the required movement required to place the rail 19 in a desired profile for the next pass. 5 Fig. 7 illustrates the roof supports 23 in greater detail. The roof supports 23 may operate in a semi-automated control mode such the roof supports 23 are able to receive control signals from the processor 12 and from user operated manual controls, for example hydraulic controls. The roof supports 23 may also operate in a substantially 10 fully-automated control mode such that only the roof support 23 is able to receive control signals from only the processor. In another example a user external to the mining machine 7 monitors the roof supports 23 via an external user interface and using the user interface is able to send control signals to the roof supports. In yet another example the automation of the roof supports 23 connects to the control of the 15 shearer 9 via the processor 102. Fig. 7a illustrates an exemplary roof support 23, as one of multiple roof supports, in an engaged state where the canopy 400 of the roof support 23 is engaged with the mine roof being the underlying surface of the overlying strata 13. In this state the canopy 20 400 supports the mine roof and the hydraulic arm 402 of the roof support 23 extends and exerts pressure upon the mine roof. The hydraulic arm 402 may be powered by a power pack system located on or near to the roof support 23. In another example the roof support comprises spillboards which are shields mounted on the canopy 400 of the roof support 23. The spillboards prevent excessive coal from falling from the mining 25 face 3. As the roof support 23 advances towards the seam 1 the spillboards are placed against the mining face 3. The spillboards maintain a safe distance from the moveable carriage 17 and as the shearer 9 approaches the roof support 23 the spillboards fold back up into the canopy 400 to avoid damage. 30 As described in step 206 once the processor 102 determines that the moveable carriage 17 has completely passed a roof support 23 such that the trailing end of the moveable 20 carriage 17 has passed the leading edge of the roof support 23, the processor 102 generates a control signal for the moving element 25 connected to the roof support 23 to move a distance 27. This control signal communicates to the roof support 23 to assume the disengaged state as illustrated in Fig. 7b. In the disengaged state the canopy 5 400 of the roof support 23 is not in contact with the mine roof. In this state the canopy 400 does not support the mine roof and the hydraulic arm 402 of the roof support 23 releases pressure on the mine roof and the canopy 400 is lowered. The roof support 23 is moveable by the moving element 25 and the rail 19 provides a fixed position for the moving element 25 to move the roof support 23 such that the roof support 23 advances 10 a distance 27 from the stationary rail 19. This is illustrated in Fig. 7c where the roof support 23, in a disengaged state, advances towards the seam 1 by a distance 27. The distance 27 that the roof support 23 advances assists the rail 19 in the subsequent stage to assume the desired profile. The control signal that the processor 102 generates also communicates to the roof supports 23 to assume the engaged state as illustrated in Fig. 15 7d. In this engaged state the roof support 23 acts as a fixed position for the moving element 25 to move the rail 19 such that the rail 19 advances a predefined distance 404 forward from the engaged roof support 23. The moving element 25 pushes the rail 19 as illustrated in Fig. 7e, where the exemplary roof support 23 is in an engaged state while the rail 19 moves a predefined distance 404 to assume the desired profile for the 20 next traversal. The predefined distance 404 is independent of the absolute co-ordinate position of the rail 19. In the present disclosure the processor 102 calculates the distance 27 for the roof supports 23 to advance in real-time, that is, in the same traversal. This means that the 25 immediate advancement of the roof support 23 is based on the most up-to-date position of the rail 19, as the distance 27 the roof support 23 advances is partially based on the absolute co-ordinate position of the moveable carriage 17 and thereby rail 19. Fig. 8 is a plan view of an example of the present disclosure as described above with 30 the different stages along a traversal shown. The roof supports 23" have advanced by the distance 27 and the rail 19" has subsequently pushed. The roof support 23' has 21 advanced the distance 27 but the moving element 25 has not yet pushed the rail 19'. The roof supports 23 to the right of the plan view of the mining machine 7 are yet to be advanced or pushed as the moveable carriage 17 has not passed, as such the moving elements have not received the control signal from processor 102, and the roof supports 5 23 are in the same position as the previous traversal. Fig. 9 illustrates a simplified example of the present disclosure. A series of plan views are shown of a seam 1, similar to that in Fig. 6. Rail 19 extends across the mining face 3 and the mining machine 7 traverses the rail 19. Each of the views in Fig. 9a to 9c is a 10 plan view showing the seam 1 and rail 19 in an approximate horizontally extending plane. It should be recognised that coal seams typically extend transversely in a generally horizontally extending plane, however, there are undulations and inclinations as exemplified in Figs. 1 and 2. 15 Fig. 9a illustrates the seam 1 with a mining face 3 prior to commencement of mining using the mining machine 7. It can be seen that the rail 19 extends in front of the mining face 3. Typically, the profile of the rail is to be a straight line. The mining machine 7 is shown at the extreme left hand side of the seam 1 prior to making a pass to the right hand side of the seam 1. It can be seen that the mining face 3 has a profile 20 which is different to the profile of the rail 19. In Fig. 9a, the at least 2D co-ordinate positioning system 300 determines a 2D co-ordinate position of the mining machine 7 prior to commencing shearing. This is typically a Northing and Easting co-ordinate position of the machine, and this initial 2D co-ordinate position acts as a datum for the machine 7 to commence shearing. 25 Fig. 9b shows the arrangement after a first pass of the mining machine 7. Here it can be seen that the profile of the mining face 3 now replicates the profile of the rail 19, as the rail 19 moves to assume the desired profile. It may require several passes and corresponding movements of the rail 19 to reach the desired profile as the roof supports 30 23 have only a limited movement capability. That means that the desired profile for each traversal may not be the ultimately desired profile, but simple the best profile that 22 can be achieved in the next pass. The ultimate desired profile, which may extend in a straight line, is such that the mining machine 7 advances into the mining face 3 with an approximate equal depth of cut with each traversal. 5 Fig. 9c shows that the profile of the rail has been adjusted to the desired profile, in this case a straight line, by appropriately moving the rail 19 at various locations behind the mining machine 7 during the traversal across the mining face 3. It is possible to assume a desired profile of the rail 19, and a corresponding profile of the mining face 3, by knowing the co-ordinate positions of the mining machine 7 at various locations 10 along the rail 19. This is because the mining machine 7 is carried by the rail 19, and the co-ordinate positions of the mining machine 7 are directly related to the position of the rail 19 at these locations. Thus, the co-ordinate positions are preferably determined from a fixed point on the mining machine 7 and the current position of the rail 19 is related to the fixed point. In a variation the co-ordinate positions may be determined 15 using co-ordinate determining system mounted on the rail directly and not on the moveable mining machine. Those locations 500 may correspond exactly with the positions where multiple roof supports 23 connect with the rail 19 or there may be many intermediate locations. 20 In other words, the number of locations along the rail 19 where the co-ordinate positions of the mining machine 7 are determined may be far greater in number than the number of multiple roof supports 23. Fig. 10 illustrates the locations 500 where the co ordinate positions of the mining machine 7 may be determined. Fig. 10a illustrates one location per roof support 23 and Fig. 10b illustrates more than 5 locations associated 25 with one of the multiple roof supports 23. In Fig. 10a the processor 102 determines the distance 27 based on one location, that is the processor 102 essentially determines the location as a selection of which roof support the mining machine is closest to or has just passed. Alternatively, as shown in 30 Fig. 10b the processor 102 determines the distance 27 based on more than five locations, that is the processor 102 is able to determine the location with a greater 23 accuracy, since the distance a roof support 23 extends along the rail is divided into five different positions. In another example, determining the distance 27 is based on more than 100 locations 5 associated with one of the multiple roof supports 23. In yet another example determining the distance 27 is based on between 5 and 2000locations associated with the one of the multiple roof supports. It is assumed that the distance 27 which each roof support 23 advances towards the 10 seam 1 so that the rail 19 assumes the desired profile is the required distance without any slippage of the roof supports 23. In practice some slippage may occur, however, the position determining system 300 is such that it will always be able to determine the current position of the mining machine 7 at the various locations, and thus any calculation of the required distance 27 will always be based on the current position and 15 not the expected position. Thus, the techniques of the present disclosure minimise the problems of the rail 19 assuming a non-desired curvilinear or snake path after many passes. In addition to this it is not necessary to shut down the mining machine 7 to attempt to adjust the rail 19 after many passes, as has been the case in prior art systems, as the profile of the rail 19 is either the same as the desired profile or approximately so. 20 In another example of the present disclosure small adjustments can be made with the system to incline the rail 19 relative to the mining face 3 to move the rail 19 and thus mining machine 7 either left or right in a steering-type arrangement to compensate for any graduate creepage of the mining machine 7 and rail 19 to one side of the seam 1. 25 For instance, if the machine 7 were attempting to mine a seam such as that shown in Fig. 1 which has a dramatic upwards inclination. Fig. 9d illustrates the profile of the rail 19 similar to that in Fig. 9a. Fig. 9d also illustrates a number of locations 500 X 1 , X 2 , X 3 ,... XN along the length of the rail 19. 30 Fig. 9e illustrates the desired profile 19' of the rail 19 and shows a corresponding number of locations in Y,Y2, ..-- N at the same incremental locations as 24

X

1 , X 2 , X 3 ,... XN in Fig. 9d. It is assumed that AX and AY are the differences between two adjacent locations and both AX and AYremain constant. Then, at each of the locations represented by the vector quantities X 1 , X 2 , X 3 ,... XN, the heading of the machine can be used to determine the co-ordinates at these locations as follows: 5 X, = X,_+ AX/On where AXZOn is a vector expressed in polar form having magnitude AX and angle 0s where /_0 is a suitable constant valued representation of the heading of the machine throughout the actual path between locations Xn_ and Xn. Preferably the co ordinates are determined as Easting and Northing. The length of displacement 10 4, A4, 4,... AN can then be determined to place the rail 19 at the required position so that the desired profile 19' will be obtained. This is illustrated in Figs. 9f and 9g. At any given point the length of displacement A can be expressed by the following: A =IX -Xn I 15 where I X I denotes the magnitude of the vector X . The above simple system can then be expanded to a 3D co-ordinate system where the position determining system 300 determines the altitude of the machine 7 at each of the various locations X 1 , X 2 , X 3 ... XN. By knowing the 3D co-ordinates at each of the 20 positions X 1 , X 2 , X 3 ,... XN it is possible to store a 3D profile of the seam 1. In this disclosure any reference to "at least 2D" encompasses 3D. In the example of the present disclosure, an inertial navigation system (INS) is used to determine the 3D position and orientation of the mining machine 7 in three dimensions. 25 Preferably, each of the three dimensions is based on the X, Y, and Z co-ordinates. Typically, a gyroscopic system measures the angular velocity in each of the three co ordinates. The gyroscopic system may, in turn, be associated with accelerometers which measure the 3D acceleration (linear) in the same co-ordinate dimensions. The position determining system 300 further comprises a first odometer and a second 25 odometer to improve the accuracy and stability of the INS, where the odometers provide information about the linear displacement of the mining machine system. A first resolution of distance measurements of the first odometer is less than a second resolution of distance measurements of the second odometer, for example, the first 5 odometer has a resolution of less than 10 distance measurements per metre and the second odometer has a resolution of more than 100 distance measurements per metre. In one example of the present disclosure the first odometer provides absolute distance measurements and the second odometer provides incremental distance measurements. 10 In another example both the first and the second odometer provide absolute distance measurements. The position determining system 300 then processes the signals for each of the three dimensions and extracts the linear position and angular rotation. This uniquely defines 15 the exact position of the machine 7 and rail 19 in 3D space. The position determining system 300 determines the attitude angle, associated with each distance measurement and uses the distance measurements and associated attitude angles to determine the absolute co-ordinate position of the machine 7 and rail 19. 20 Inaccuracies may occur if the machine does not follow a straight line, that is, the attitude angle of the machine changes between subsequent measurements of the attitude angle. The above process approximates the absolute co-ordinate position by an estimate that assumes movement along a straight line rather than a curved path. The error may be reduced if the attitude angle and distance are measured more frequently, 25 that is, with a higher resolution along the track. In one example, the carriage carries a low resolution absolute odometer that is part of the standard installation of the machine. Absolute in this context means that the odometer provides an overall distance from when the odometer was first started to be used. 30 The carriage may further carry a retrofitted high resolution incremental odometer. Incremental in this context means that the odometer provides the distance from the last 26 measurement. For example, the odometer simply provides a binary signal that rises from low to high. Data memory 106 stores a distance that is associated with the high resolution odometer, such that processor 102 can determine that each time the processor 102 detects a rising edge on the odometer signal, the carriage has moved by 5 that distance. For example, if the resolution of the odometer is known to be 100 measurements per metre, the associated distance per rising edge is 1 cm. Each time processor 102 detects a rising edge, processor 102 determines the absolute coordinate position based on the high resolution odometer distance and the attitude 10 angle. Since the sampling rate of the path of the carriage is now increased, the location error is reduced. Further, the retrofitting of an incremental odometer with high resolution is relatively inexpensive while the use of an absolute odometer limits the accumulated error caused by incremental odometer measurements. In other words, this combination of absolute and incremental odometers has the particular advantages of 15 low cost and high accuracy. As seen in Fig. 10(b) multiple locations 500 are associated with each roof support 23. In one example, processor 102 selects the location that is closest to the moving element 25 with respect to the horizontal position in order to determine the distance by which to 20 move the rail. In one example, processor 102 interpolates between the two closest locations on either side of the moving element. In these examples, determining the distance is independent of the locations other than the one or two closest locations. It is noted that although only one or two locations are selected to determine the advancement distance, using a larger number of locations for determining the positions 25 increases the accuracy of the determined position as described above. In a typical example, a linear transverse drive motor system mounted on the mining machine 7 controls the required movement of the machine 7 in the X direction, i.e. side-to-side across the seam 1. By adjusting the lower limit of the shearer head 9 the 30 required movement of the machine 7 in the Z direction can be controlled. As this lower limit defines the floor upon which the rail will subsequently sit, this lower limit 27 determines the profile of the rail in the Y direction. The upper limit is important only from a maximum extraction perspective. Various approaches determine the lower limit, for example motor torque, gamma 5 detection, mimic cut, visual reference. In this respect the INS as described above improves the accuracy, stability and overall effectiveness of such techniques when used together. The moveable carriage 17 carries swingable arms 21 which, in turn, support the 10 shearing heads 9 at each end of the moveable carriage 17. The arms 21 can swing upwardly and downwardly whilst the moveable carriage 17 can traverse the rail 19. Once the lower limit is determined, an appropriate drive system such as hydraulic motors may be employed to swing the arms 21 in subsequent side-to-side passes of the machine 7, so that the shearing heads 9 remove all possible relevant material from the 15 seam 1 during each pass without unduly mining the strata 11 or mine roof 13. The inertial movement sensor mounted on the mining machine measures the movement of the mining machine 7 in the Y direction, where the Y direction is the direction of progression of mining. The processor 102 uses knowledge of the desired 3D absolute 20 position of the mining machine 7 and the distance of travel along rail 19, together with the upper and lower limits of the seam 1 in the Y direction to produce output control signals to appropriately move the mining machine 7 relative to the rail 19 and the shearing heads 9 relative to the mining machine 7, such that precise control of mining can be effected. 25 Thus, the processor 102 provides output signals to effect forward movement to a preselected absolute position of the rail. Further, the output signals that the processor provides to the roof supports 23 may be such as to cause the mining machine 7 to cut at a preselected absolute geodetic heading or angle relative to the shearing heads, such 30 that the machine 7 cuts the mining face 3 at a preselected absolute geodetic heading or angle relative to the forward progression of the rail into the seam 1.

28 The processor 102 includes a program memory 104 and data memory 106 which stores information concerning the electrical signals provided by the at least 2D position determining system 300 at various points throughout the traversal of the machine 7 along rail 19. The processor 102 then requests, retrieves and uses the signals stored in 5 the memory 104 and 106 to calculate the required rail movements. In another example the position determining system 300 provides signals in each of the X, Y, and Z planes and stores a profile of the positions during each traversal of the shearing head 9 along the rail 19, such that on subsequent passes the shearing head 10 position control system (for example hydraulic motors) controls the movement of the shearing head 9. The shearing head position control system may move the shearing head 9 upwardly or downwardly to positions which cause the shearing head 9 to traverse a similar profile as the last traversal but at a shearing depth determined from the forward position of the rail 19. This enables the shearing head position control 15 system to predict the likely or expected position of the shearing heads 9 during any subsequent pass such that the shearing heads 9 can follow pre-found folds or contours of the seam 1. As each traversal passes the profile likely changes, however, this change can be predicted for the next cut or series of cuts. Therefore, this achieves tighter control over mining than with known prior art systems. 20 The position determining systems outlined above are merely exemplary forms of typical position determining systems which can be used and should not be considered limiting. Fig. 11 illustrates an electrical block circuit diagram which shows the functional elements of the electrical part of the processing of the 3D co-ordinate 25 positioning system 300. In this example an INS determines the position of the mining machine 7. The first and second odometers measure the distance travelled by the mining machine 7 on the rail 19 and also stabilise and improve the accuracy of the INS. This in turn determines the position of the mining machine across the mining face such that X 1 , X 2 , X 1 3 , ... XN can be determined. 30 29 The processor 102 receives the output signals from the INS and odometers. In one example the processor 102 is mounted on the moveable carriage 17 such as by permanent fixing of a housing of the computer system 100 within which the processor 102 lies by welding. In other examples the housing may be removably attached to the 5 moveable carriage 17. In yet another example the processor 102 is located in close proximity to and within 10 metres from the mining machine 7. In another example the mining machine 7 comprises a cable to connect the co-ordinate positioning determining system 300 to the processor 102. The processor 102 processes the input signals and stores them in data memory 106. The processor 102 subsequently recalls and processes 10 the signals and calculates the distance 27 for the roof support 23 to advance. The processor 102 then uses the information in the data memory 106 to process the signals for the required roof supports 23 to move. Each of the moving elements 25 associated with each of the roof supports 23 receives an electrical signal output from 15 the processor 102 so as to advance the roof support 23 by a distance 27. The rail 19 subsequently moves by a predefined distance 404. Individual control circuits for effecting movement of the roof supports 23 to support the mine roof are appropriately interfaced into the processor 102. 20 Figure 11 is a software flow diagram showing the software processes from the start of a longwall mining process to the end of a longwall mining process during a mining session. The process steps are self-explanatory with the only exception being the function "HAS THE EXIT KEY BEEN PRESSED". This function is to determine that the stop button (exit key) has been pressed on the mining machine, thus, terminating a 25 mining session. Fig. 12 illustrates a drivetrain 1200 of a mining machine. Drivetrain 1200 comprises a travel mechanism, such as an electric motor 1202 connected to a gearbox 1204 that is connected to shaft 1206. When in use, the shaft 1206 is driven by interaction with 30 motor 1202 via gearbox 1204. Mounted on shaft 1206 are a first odometer 1208 and a second odometer 1210.

30 First odometer 1208 comprises a quadrature encoder 1212 connected to shaft 1206, a light source 1214, such as an LED, a lens 1216 and a photo detector 1218. As illustrated in Fig. 12, quadrature encoder 1212 comprises alternating transparent sections (shown in white) and occluding sections (shown in black). An outer ring 1220 5 comprises four sections, while an inner ring 1222 comprises eight sections. Light from the LED 1214 is focussed by lens 1216 and passes through the quadrature encoder 1212. As the quadrature encoder 1212 rotates together with shaft 1206 the light is alternatingly blocked or transmitted, which results in a square waveform at the output of the photo detector 1218. The frequency of the square waveform is directly related to 10 the rotation speed of the shaft 1206. As the quadrature encoder has two rings 1220 and 1222 the photo detector 1218 outputs two square waveforms where one square waveform has twice the frequency of the other square waveform. Processor 102 in Fig. 4 is connected to photo detector 1218 15 and receives the square waveforms. By detecting the relationship between the two square waveforms processor 102 can determine the direction of rotation as well as the speed of rotation. More particularly, at each rising or falling edge of the square waveform the processor 20 102 determines that the mining machine has moved by a predefined distance. For example, the circumference of the wheels of the mining machine is 0.8 m and as a result, each rotation of the shaft relates to a moved distance of 0.8 m. Since the inner ring 1222 comprises eight transitions between transparent and occluding sectors, each edge of the square waveform associated with the inner ring 1222 corresponds to a 25 movement of 0.1 m, that is, the odometer 1208 provides a quadrature pulse every 0.1 m travel. Second odometer 1210 comprises similar components to first odometer 1208. In particular, second odometer 1210 comprises a quadrature encoder 1230 comprising an 30 outer ring and an inner ring 1234. As can be seen in Fig. 12, the number of sectors of the outer ring 1232 and the inner ring 1234 of the second odometer 1210 is 31 significantly higher than the number of sectors of the outer ring 1220 and the inner ring 1222 of the first odometer 1208. As a result, the resolution of distance measurements of the first odometer 1208 is less than the resolution of distance measurement of the second odometer 1208. In one example, the inner ring 1222 comprises 80 sectors and 5 as a result, the second odometer provides a quadrature pulse every 0.01 m travel. It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the specific embodiments without departing from the scope as defined in the claims. 10 It should be understood that the techniques of the present disclosure might be implemented using a variety of technologies. For example, the methods described herein may be implemented by a series of computer executable instructions residing on a suitable computer readable medium. Suitable computer readable media may include 15 volatile (e.g. RAM) and/or non-volatile (e.g. ROM, disk) memory, carrier waves and transmission media. Exemplary carrier waves may take the form of electrical, electromagnetic or optical signals conveying digital data steams along a local network or a publically accessible network such as the internet. 20 It should also be understood that, unless specifically stated otherwise as apparent from the following discussion, it is appreciated that throughout the description, discussions utilizing terms such as "estimating" or "processing" or "computing" or "calculating", "optimizing" or "determining" or "displaying" or "maximising" or the like, refer to the action and processes of a computer system, or similar electronic computing device, that 25 processes and transforms data represented as physical (electronic) quantities within the computer system's registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage, transmission or display devices. 30 The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims (20)

1. A mining machine comprising: a shearing head mounted on a moveable carriage, said shearing head being for mining product from a seam as said moveable carriage traverses from side-to-side 5 across a mining face of said seam on a rail which extends from side-to-side across the seam; multiple roof supports to support a mine roof after mining the product from the seam, each of the multiple roof supports being connected to the rail by a respective moving element; 10 an at least 2D co-ordinate position determining system to determine an absolute co-ordinate position in space of the moveable carriage at one or more locations along the rail during a first traversal, each of the one or more locations being associated with one of the multiple roof supports, said position determining system providing absolute co-ordinate position output data signals therefrom; 15 a processor to receive the absolute co-ordinate position output data signals, to determine during the first traversal of the moveable carriage a distance by which to move the one of the multiple roof supports towards the seam based on the absolute co-ordinate position determined during the first traversal and 20 based on a desired profile; to determine during the first traversal that the moveable carriage has passed the one of the multiple roof supports; and upon determining during the first traversal that the moveable carriage has passed the one of the multiple roof supports, to generate a control signal for the 25 moving element connected to the one of the multiple roof supports to move during the first traversal the one of the multiple roof supports by the distance determined during the first traversal such that when the moving element connected to the one of the multiple roof supports moves the rail, the rail assumes the desired profile.

2. The mining machine of claim 1, wherein 30 each of the multiple roof supports has an engaged state where that roof support is engaged with the mine roof such that the roof support provides a fixed position for 33 the moving element to move the rail, each of the multiple roof supports has a disengaged state where the roof support is moveable by the moving element while the rail provides a fixed position for the moving element to move that roof support, 5 and to generate the control signal comprises to generate the control signal for the one of the multiple roof supports to assume the disengaged state during the first traversal when moving the one of the multiple roof supports by the distance determined during the first traversal and to assume the engaged state when moving the rail during the first traversal to assume the desired profile for the second traversal. 10

3. The mining machine of claim 2, wherein the moving element connected to the one of the multiple roof supports moves the rail by a predefined distance that is independent of the absolute co-ordinate position.

4. The machine of any one of the preceding claims, wherein the processor is 15 located within 10 metres from the mining machine.

5. The machine of any one of the preceding claims, further comprising a cable to connect the co-ordinate position determining system to the processor.

6. The mining machine of any one of the preceding claims, wherein the processor 20 is mounted to the mining machine or to the moveable carriage.

7. The mining machine of any one of the preceding claims, wherein the one or more locations associated with one of the multiple roof supports comprises more than 5 locations associated with one of the multiple roof supports such that determining the distance is based on more than 5 locations. 25

8. The mining machine of claim 7, wherein the one or more locations associated with one of the multiple roof supports comprises more than 100 locations associated with one of the multiple roof supports such that determining the distance is based on more than 100 locations. 34

9. The mining machine of claim 8, wherein the one or more locations associated with one of the multiple roof supports comprises between 5 and 2000 locations associated with one of the multiple roof supports such that determining the distance is based on between 5 and 2000 locations. 5

10. The mining machine of any one of the preceding claims, wherein the position determining system comprises a first odometer and a second odometer and a first resolution of distance measurements of the first odometer is less than a second resolution of distance measurements of the second odometer. 10

11. The mining machine of claim 10, wherein the first odometer has a resolution of less than 10 distance measurements per metre and the second odometer has a resolution of more than 100 distance measurements per metre. 15

12. The mining machine of claim 10 or 11, wherein the first odometer is to provide absolute distance measurements and the second odometer is to provide incremental distance measurements.

13. The mining machine of claim 10 or 11, wherein the first odometer is to provide 20 absolute distance measurements and the second odometer is to provide absolute distance measurements.

14. A method for controlling a mining machine, the mining machine comprising: a shearing head mounted on a moveable carriage, said shearing head being for 25 mining product from a seam as said moveable carriage traverses from side-to-side across a mining face of said seam on a rail which extends from side-to-side across the seam; and multiple roof supports to support a mine roof after mining the product from the seam, each of the multiple roof supports being connected to the rail by a respective 30 moving element; the method comprising: 35 receiving absolute co-ordinate position output data signals from an at least 2D co-ordinate position determining system for determining an absolute co-ordinate position in space of the moveable carriage at one or more locations along the rail during a first traversal, each of the one or more locations being associated with one of the 5 multiple roof supports, said position determining system, determining during the first traversal of the moveable carriage a distance by which to move the one of the multiple roof supports towards the seam based on the absolute co-ordinate position determined during the first traversal and based on a desired profile; 10 determining during the first traversal that the moveable carriage has passed the one of the multiple roof supports; and upon determining during the first traversal that the moveable carriage has passed the one of the multiple roof supports, generating a control signal for the moving element connected to the one of the multiple roof supports to move during the first 15 traversal the one of the multiple roof supports by the distance determined during the first traversal such that when the moving element connected to the one of the multiple roof supports moves the rail, the rail assumes the desired profile.

15. The method of claim 14, wherein generating the control signal for the moving element comprises generating the control signal such that when the moving element 20 connected to the one of the multiple roof supports moves the rail, the rail assumes the desired profile for a second traversal immediately after the first traversal.

16. The method of claim 14 or 15, wherein generating the control signal for the moving element comprises generating the control signal such that when the moving element connected to the one of the multiple roof supports moves the rail, the rail 25 assumes the desired profile for a remainder of the first traversal.

17. The method of any one of claims 14 to 16, wherein generating the control signal is performed before determining that the moveable carriage has passed any subsequent roof support of the multiple roof supports. 36

18. The method of any one of claims 14 to 17, wherein determining the distance by which to move the one of the multiple roof supports towards the seam comprises determining the distance based on the absolute co-ordinate position at one or more selected locations associated with the one of the multiple roof supports and independent 5 of the absolute co-ordinate position at locations associated with the one of the multiple roof supports other than the selected locations.

19. Software that, when executed by a computer, causes the computer to perform the method of any one of claims 14 to 18. 10

20. A mining machine comprising: two or more shearings heads each mounted upon an arm connected via a rotatable joint to a moveable carriage, said shearing head being for mining product from a seam as said moveable carriage traverses from side-to-side across a mining face of said seam on a rail which extends from side-to-side across the seam; and 15 multiple roof supports to support a mine roof after mining the product from the seam, each of the multiple roof supports being connected to the rail by a respective moving element; characterised in that the mining machine further comprises: an at least 2D co-ordinate position determining system to determine an absolute co ordinate position in space of the moveable carriage at one or more locations along the 20 rail during a first traversal, each of the one or more locations being associated with one of the multiple roof supports, said position determining system providing absolute co ordinate position output data signals therefrom; and a processor comprising: an absolute co-ordinate position output data signals receiving unit 25 receiving the absolute co-ordinate position output data signals from said position determining system, a distance determining unit determining during the first traversal of the moveable carriage a distance by which to move the one of the multiple roof supports towards the seam based on the received absolute co-ordinate position output data 30 signals and based on a desired profile; a passing determining unit determining during the first traversal that the 37 moveable carriage has passed the one of the multiple roof supports; and a control signal generating unit, upon the passing determining unit determining during the first traversal that the moveable carriage has passed the one of the multiple roof supports, generating a control signal for the moving element 5 connected to the one of the multiple roof supports to move during the first traversal the one of the multiple roof supports by the distance determined by the distance determining unit such that when the moving element connected to the one of the multiple roof supports moves the rail, the rail assumes the desired profile. 10