Abstract:
A system and corresponding method of monitoring a longwall shearing mining machine in a longwall mining system, where the shearing mining machine includes a shearer having a cutter drum, the method includes obtaining, by a processor, desired pitch angle information, and receiving, by the processor, a pitch angle indicative of a current pitch position of the shearer. The method also includes determining, by the processor, whether the pitch angle is within a desired pitch angle range, and controlling, by the processor, a position of the cutter drum based on whether the pitch angle is within the desired pitch angle range. The desired pitch angle range is based on the desired pitch angle information.

Description:
FIELD OF INVENTION 
     The present invention relates to monitoring shearer position of a longwall mining system. 
     SUMMARY 
     In one embodiment, the invention provides a method of monitoring a longwall shearing mining machine in a longwall mining system. The shearing mining machine includes a shearer having a cutter drum. The method includes obtaining, by a processor, desired pitch angle information and receiving, by the processor, a pitch angle indicative of a current pitch position of the shearer. The method also includes determining, by the processor, whether the pitch angle is within a desired pitch angle range. The desired pitch angle range is based on the desired pitch angle information. The method also further includes controlling, by the processor, a position of the cutter drum based on whether the pitch angle is within the desired pitch angle range. 
     In another embodiment the invention provides a monitoring device for a longwall mining system including a shearer having a cutter drum and a sensor to determine a pitch position of the shearer. The monitoring device includes a monitoring module implemented on a processor in communication with the shearer to obtain desired pitch angle information and receive a pitch angle indicative of a current pitch position of the shearer. The monitoring module includes an analysis module configured to determine whether the pitch angle is within a desired pitch angle range. The pitch angle range is based on the desired pitch angle information. The monitoring module also includes a correction module that is configured to control a position of the cutter drum based on whether the pitch angle is within the desired pitch angle range. 
     Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an extraction system according to one embodiment of the invention. 
         FIGS. 2A-B  illustrate a longwall mining system of the extraction system of  FIG. 1 . 
         FIG. 3  illustrates collapsing of the geological strata as mineral is removed from the mineral seam. 
         FIG. 4  illustrates a powered roof support of the longwall mining system. 
         FIG. 5  illustrates another view of the roof support of the longwall mining system. 
         FIGS. 6A-B  illustrate a longwall shearer of the longwall mining system. 
         FIGS. 7A-B  illustrate a longwall shearer as it passes through a coal seam. 
         FIG. 8  illustrates approximate locations for sensors positioned in the shearer of the longwall mining system. 
         FIG. 9  is a schematic diagram of a controller of the shearer of  FIGS. 6A-B . 
         FIG. 10  is a schematic diagram of a monitoring module of the longwall mining system. 
         FIG. 11  is a schematic diagram illustrating the monitoring thresholds for the shearer of the longwall mining system. 
         FIG. 12  is a flowchart illustrating a method of monitoring a pitch shearer position. 
         FIG. 13  is a schematic diagram of the health monitoring system of the extraction system shown in  FIG. 1 . 
         FIG. 14  is a schematic diagram of the longwall control system of the health monitoring system of  FIG. 13 . 
         FIG. 15  illustrates an exemplary e-mail alert. 
     
    
    
     DETAILED DESCRIPTION 
     Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. 
     In addition, it should be understood that embodiments of the invention may include hardware, software, and electronic components or modules that, for purposes of discussion, may be illustrated and described as if the majority of the components were implemented solely in hardware. However, one of ordinary skill in the art, and based on a reading of this detailed description, would recognize that, in at least one embodiment, the electronic based aspects of the invention may be implemented in software (e.g., stored on non-transitory computer-readable medium) executable by one or more processors. As such, it would be noted that a plurality of hardware and software based devices, as well as a plurality of different structural components, may be utilized to implement the invention. Furthermore, and as described in subsequent paragraphs, the specific mechanical configurations illustrated in the drawings are intended to exemplify embodiments of the invention. However, other alternative mechanical configurations are possible. For example, “controllers” and “modules” described in the specification can include one or more processors, one or more computer-readable medium modules, one or more input/output interfaces, and various connections (e.g., a system bus) connecting the components. In some instances, the controllers and modules may be implemented as one or more of general purpose processors, digital signal processors DSPs), application specific integrated circuits (ASICs), and field programmable gate arrays (FPGAs) that execute instructions or otherwise implement their functions described herein. 
       FIG. 1  illustrates an extraction system  100 . The extraction system  100  includes a longwall mining system  200  and a health monitoring system  400 . The extraction system  100  is configured to extract an ore or a mineral, for example, coal from a mine in an efficient manner. In other embodiments, the extraction system  100  is used to extract other ores and/or minerals. For example, in some embodiments, Trona, a non-marine evaporate mineral, is extracted using a longwall mining system. The longwall mining system  200  includes tools, for example, a shearer  300 , to physically extract coal, or another mineral, from an underground mine. The health monitoring system  400  monitors operation of the longwall mining system  200  to, for example, ensure that extraction of the mineral remains efficient, detect equipment problems, and the like. 
     Longwall mining begins with identifying a mineral seam to be extracted, then “blocking out” the seam into mineral panels by excavating roadways around the perimeter of each panel. During excavation of the seam (i.e., extraction of coal), select pillars of mineral can be left unexcavated between adjacent mineral panels to assist in supporting the overlying geological strata. The mineral panels are excavated by the longwall mining system  200 , and the extracted mineral is transported to the surface of the mine. 
     As illustrated in  FIGS. 2A-2B , the longwall mining system  200  includes roof supports  205 , a longwall shearer  300 , and an armored face conveyor (AFC)  215 . The longwall mining system  200  is generally positioned parallel to the mineral face  216  (see  FIG. 3 ). The roof supports  205  are interconnected parallel to the mineral face  216  (see  FIG. 3 ) by electrical and hydraulic connections. Further, the roof supports  205  shield the shearer  300  from overlying geological strata  218  (see  FIG. 3 ). The number of roof supports  205  used in the mining system  200  depends on the width of the mineral face  216  being mined since the roof supports  205  are intended to protect the full width of the mineral face  216  from the strata  218 . 
     The shearer  300  is propagated along the line of the mineral face  216  by the AFC  215 , which includes a dedicated track for the shearer  300  running parallel to the mineral face  216 . The shearer track is positioned between the mineral face  216  itself and the roof supports  205 . As the shearer  300  travels the width of the mineral face  216 , removing a layer of mineral, the roof supports  205  automatically advance to support the roof of the newly exposed section of strata  218 . 
       FIG. 3  illustrates the mining system  200  advancing through the mineral seam  217  as the shearer  300  removes mineral from the mineral face  216 . The mineral face  216  illustrated in  FIG. 3  extends perpendicular from the plane of the figure. As the mining system  200  advances through the mineral seam  217  (to the right in  FIG. 3 ), the strata  218  is allowed to collapse behind the mining system  200 , forming a goaf  219 . The mining system  200  continues to advance forward and shear more mineral until the end of the mineral seam  217  is reached. 
     While the shearer  300  travels along the side of the mineral face  216 , extracted mineral falls onto a conveyor included in the AFC  215 , parallel to the shearer track. The mineral is transported away from the mineral face  216  by the conveyor. The AFC  215  is then advanced by the roof supports  205  toward the mineral face  216  by a distance equal to the depth of the mineral layer previously removed by the shearer  300 . The advancement of the AFC  215  allows the excavated mineral from the next shearer pass to fall onto the conveyor, and also allows the shearer  300  to engage with the mineral face  216  and continue shearing mineral away. The conveyor and track of the AFC  215  are driven by AFC drives  220  located at a maingate  221  and a tailgate  222 , which are at distal ends of the AFC  215 . The AFC drives  220  allow the conveyor to continuously transport mineral toward the maingate  221  (left side of  FIG. 2A ), and allows the shearer  300  to be pulled along the track of the AFC  215  bi-directionally across the mineral face  216 . 
     The longwall mining system  200  also includes a beam stage loader (BSL)  225  arranged perpendicularly at the maingate end of the AFC  215 .  FIG. 2B  illustrates a perspective view of the longwall mining system  200  and an expanded view of the BSL  225 . When the extracted mineral hauled by the AFC  215  reaches the maingate  221 , the mineral is routed through a 90° turn onto the BSL  225 . In some instances, the BSL  225  interfaces with the AFC  215  at a non-right 90° angle. The BSL  225  then prepares and loads the mineral onto a maingate conveyor (not shown) which transports the mineral to the surface. The mineral is prepared to be loaded by a crusher  230 , which breaks down the mineral to improve loading onto the maingate conveyor. Similar to the conveyor of the AFC  215 , the conveyor of the BSL  225  is driven by a BSL drive. 
       FIG. 4  illustrates the longwall mining system  200  as viewed along the line of the mineral face  216 . The roof support  205  is shown shielding the shearer  300  from the overlying strata  218  by an overhanging canopy  236  of the roof support  205 . The canopy  236  is vertically displaced (i.e., moved toward and away from the strata  218 ) by hydraulic legs  250 ,  252  (only one of which is shown in  FIG. 4 ). The canopy  236  thereby exerts a range of upward forces on the geological strata  218  by applying different pressures to the hydraulic legs  250 ,  252 . Mounted to the face end of the canopy  236  is a deflector or sprag  242 , which is shown in a face-supporting position. However, the sprag  242  can also be fully extended, as shown in ghost, by a sprag arm  244 . An advance ram  246  attached to a base  248  allows the roof support  205  to be pulled toward the mineral face  216  as the layers of mineral are sheared away.  FIG. 5  illustrates another view of the roof support  205 .  FIG. 5  shows a left hydraulic leg  250  and a right hydraulic leg  252 , which support the canopy  236 . Both the left hydraulic leg  250  and the right hydraulic leg  252  contain pressurized fluid to support the canopy  236 . 
       FIGS. 6A-6B  illustrate the shearer  300 .  FIG. 6A  illustrates a perspective view of the shearer  300 . The shearer  300  has an elongated central housing  305  that stores the operating controls for the shearer  300 . Extending below the housing  305  are skid shoes  310  that support the shearer  300  on the AFC  215 . In particular, the skid shoes  310  engage the track of the AFC  215  allowing the shearer  300  to be propagated along the mineral face  216 . Extending laterally from the housing  305  are left and right cutter arms  315 ,  320 , respectively, which are movably driven by hydraulic cylinders enclosed within a right arm motor housing  325  and a left arm motor housing  330 . The hydraulic cylinders are part of a right arm hydraulic system  386  configured to articulate the right cutter arm  315 , and a left arm hydraulic system  388  configured to articulate the left cutter arm  320 . 
     On the distal end of the right cutter arm  315  (with respect to the housing  305 ) is a right cutter  335 , and on the distal end of the left cutter arm  320  is a left cutter  340 . Each of the cutters  335 ,  340  has a plurality of mining bits  345  that abrade the mineral face  216  as the cutters  335 ,  340  rotate, thereby cutting away the mineral. The mining bits  345  can also spray fluid from their tips, such as, for example, for dispersing noxious and/or combustible gases that develop at the excavation site. The right cutter  335  is driven (e.g., rotated) by a right cutter motor  355  while the left cutter  340  is driven (e.g., rotated) by a left cutter motor  350 . The hydraulic systems  386 ,  388  are configured to vertically move the right cutter arm  315  and the left cutter arm  320 , respectively, which changes the vertical position of the right cutter  335  and the left cutter  340 , respectively. 
     The vertical positions of the cutters  335 ,  340  are a function of the angle of the arms  315 ,  320  with respect to the main housing  305 . Varying the angle of the cutter arms  315 ,  320  with respect to the main housing  305  increases or decreases the vertical position of the cutters  335 ,  340  accordingly. For example, when the left cutter arm  320  is raised to 20° from the horizontal, the cutter  340  may experience a positive change of vertical position of, for example, 0.5 m, while when the left cutter arm  320  is lowered to −20° from the horizontal, the left cutter  340  may experience a negative change of vertical position of, for example, −0.5 m. Therefore, the vertical position of the cutters  335 ,  340  may be measured and controlled based on the angle of the cutter arms  315 ,  320  with respect to the horizontal.  FIG. 6B  illustrates a side view of the shearer  300  including the cutters  335 ,  340 ; cutter arms  315 ,  320 ; skid shoes  310 , and housing  305 .  FIG. 6B  also shows detail of a left arm motor  350  and right arm motor  355 , which are enclosed by the left arm motor housing  330  and right arm motor housing  325 , respectively. 
     The shearer  300  is displaced laterally along the mineral face  216  in a bidirectional manner, though it is not necessary that the shearer  300  cut mineral bi-directionally. For example, in some mining operations, the shearer  300  is capable of being pulled bi-directionally along the mineral face  216 , but only shears mineral when traveling in one direction. For example, the shearer  300  may be operated to cut mineral over the course of a first, forward pass over the width of the mineral face  216 , but not cut mineral on its returning pass. Alternatively, the shearer  300  can be configured to cut mineral during both the forward and return passes, thereby performing a bi-directional cutting operation.  FIGS. 7A-7B  illustrate the longwall shearer  300  as it passes over the mineral face  216  from a face-end view. As shown in  FIGS. 7A-7B , the left cutter  340  and the right cutter  335  are staggered to increase the area of the mineral face  216  being cut in each pass of the shearer. In particular, as the shearer  300  is displaced horizontally along the AFC  215 , the left cutter  340  is shown shearing mineral away from the lower half (e.g., a lower portion) of the mineral face  216  and may be referred to as a floor cutter herein, while the right cutter  335  is shown shearing mineral away from the upper half (e.g., upper portion) of the mineral face  216 . The right cutter may be referred to as a roof cutter herein. It should be understood that in some embodiments, the left cutter  340  cuts the upper portion of the mineral face  216  while the right cutter  335  cuts the lower portion of the mineral face  216 . 
     The shearer  300  also includes a controller  384  and various sensors, to enable automatic control of the shearer  300 . For example, the shearer  300  includes a left ranging arm angle sensor  360 , a right ranging arm angle sensor  365 , left haulage gear sensors  370 , right haulage gear sensors  375 , and a pitch and roll sensor  380 .  FIG. 8  shows the approximate locations of these sensors, although in some embodiments the sensors are positioned elsewhere in the shearer  300 . The angle sensors  360 ,  365  provide information regarding an angle of slope of the cutter arms  315 ,  320 . Thus, a relative position of the right cutter  335  and the left cutter  340  can be estimated using the information from the angle sensors  360 ,  365  in combination with, for example, known dimensions of the shearer  300  (e.g., length of cutter arm  315 ). The haulage gear sensors  370 ,  375  provide information regarding the position of the shearer  310  as well as speed and direction of movement of the shearer  300 . The pitch and roll sensor  380  provides information regarding the angular alignment of the shearer  300 . 
     As shown in  FIG. 8 , the pitch of the shearer  300  refers to an angular tilting toward and away from the mineral face  216 . Positive pitch refers to the shearer  300  tilting away from the mineral face  216  (i.e., when the face side of the shearer  300  is higher than the goaf side of the shearer  300 ), while negative pitch refers to the shearer  300  tilting toward the mineral face  216  (i.e., when the face side of the shearer  300  is lower than the goaf side of the shearer  300 ). The pitch position of the shearer  300  is affected by the position of the AFC  215 . Since the AFC  215  advances forward after each shearer pass, the pitch angle of the shearer  300  is determined, at least in part, by the ground line generated with the extraction of mineral (i.e., by the roof cutter  335  and the floor cutter  340 ) and on which the AFC  215  rests. In other words, when the shearer  300  is propelled forward across the mineral face  216  and extracts the mineral, the floor cutter  340  performing that extraction is removing mineral from the ground on which the AFC  215  will be positioned on the next pass. If the position of the floor cutter  340  does not change from one shearer pass to the next (i.e., as the shearer  300  advances forward through the mineral seam  217 ), the pitch angle of the shearer  300  should remain approximately the same from one shearer pass to the next because the floor cutter  340  continues to cut across the same, or approximately the same, ground level. However, if the position of the floor cutter  340  changes, either by raising or lowering the floor cutter  340 , the pitch angle of the shearer  300  will soon also change when the AFC  215  advances over this ground just cut by the floor cutter  340 . Additionally, seam irregularities and other factors may cause the angle of the ground beneath the AFC  215  to have an unexpected or undesirable angle toward or away from the mineral face  216 , which would translate to the shearer  300  (supported by the AFC  215 ), affecting the shearer pitch angle. 
     For example, if the floor cutter  340  is lowered (i.e., cuts below the bottom of the AFC  215 ), the floor cutter  340  extracts mineral or material from a portion of the mineral face  216  that is below the current level of the AFC  215 . Therefore, when the AFC  215  advances forward, at least the face side portion of the AFC  215  will be positioned on lower ground, which changes the pitch angle of the shearer  300  (e.g., decreases the pitch angle of the shearer  300 ). Analogously, if the floor cutter  340  is raised (i.e., cuts above the bottom of the AFC  215 ), the floor cutter  340  leaves (i.e., does not extract) a portion of the mineral face  216  that is above the current level of the AFC  215 . Therefore, when the AFC  215  advances forward, at least the face side portion of the AFC  215  will be positioned on higher ground, which changes the pitch angle of the shearer  300  (e.g., increases the pitch angle of the shearer  300 ). 
     Therefore, the current pitch angle of the shearer  300  depends on the ground level that supports the AFC  215 , and the future pitch angle of the shearer  300  depends on the vertical position of the floor cutter  340  because the floor cutter  340  carves out, from the mineral face  216 , the floor on which the AFC  215  will be advancing over. For example, lowering the floor cutter  340  will decrease the pitch angle of the shearer  300  as the AFC  215  advances, while raising the floor cutter  340  will increase the pitch angle of the shearer  300  as the AFC  215  advances. When the pitch of the shearer is too low, the shearer  300  risks crashing into the mineral face  216  and shutting down. However, when the pitch of the shearer  300  is too high, the shearer  300  may instead tip backward. Therefore, when the pitch of the shearer  300  operates outside of a desired pitch range, the shearer  300  increases the risk of causing downtime, and even damage to the shearer  300  or other parts of the mining system  200  (e.g., the roof support  205 ). Monitoring the position of the shearer  300  also minimizes down time of the longwall mining system  200  and minimizes the possibility of causing extraction problems such as, for example, degradation of mineral material, deterioration of mineral face alignment, formation of cavities by compromising overlying seam strata, and, in some instances, lack of monitoring may cause damage to the longwall mining system  200 . 
     The roll of the shearer  300  refers to an angular difference between the right side (e.g., the tailgate) of the shearer  300  and the left side (e.g., the maingate) of the shearer  300 , as shown in  FIG. 8 . Positive roll refers to the shearer  300  tilting toward the tailgate while negative roll refers to the shearer  300  tilting toward the maingate and away from the tailgate. Both the pitch and the roll of the shearer  300  are measured in degrees. A pitch or a roll of zero indicates that the shearer  300  is leveled. 
     The sensors  360 ,  365 ,  370 ,  375 ,  380  provide information to the controller  384  such that the operation of the shearer  300  may remain efficient. As shown in  FIG. 9 , the controller  384  is also in communication with other systems related to the shearer  300 . For example, the controller  384  communicates with the right arm hydraulic system  386  and with the left arm hydraulic system  388 . The controller  384  monitors and controls the operation of the hydraulic systems  386 ,  388  and the motors  350 ,  355  based on signals received from the various sensors  360 ,  365 ,  370 ,  275 ,  380 . For example, the controller  384  may alter the operation of the hydraulic systems  386 ,  388  and the motors  350 ,  355  based on the information received from the sensors  360 ,  365 ,  370 ,  375 ,  380 . 
     In particular, the controller  384  monitors pitch data related to the shearer  300  and controls the position of the cutters  335 ,  340  based on the pitch position of the shearer  300 . As shown in  FIG. 10 , the controller  384  includes a monitoring module  430  that monitors the shearer position data obtained through the sensors  360 ,  365 ,  370 ,  375 ,  380 . The monitoring module  430  includes an analysis module  434  that receives the position data, which includes information regarding the position of the shearer  300 , and compares the position of the shearer  300  with a desired shearer position. For example, as shown in  FIG. 11 , the analysis module  434  compares the current pitch angle  500  of the shearer  300  to a desired pitch angle  504  and a desired pitch angle range  508 . The monitoring module  430  also includes a correction module  438  that controls the operation of the shearer  300  and implements a corrective action such that the pitch position of the shearer approaches the desired shearer pitch position. 
     In some embodiments, the controller  384  also monitors and controls other operations and parameters of the shearer  300 . For example, in some embodiments, an initial cutting sequence (e.g., a pass along the mineral face  216 ) and extraction heights (e.g., heights of the cutters  335 ,  340 ) are defined by use of an offline software utility, which is then loaded on to the shearer control system as a cutting profile. Once the shearer controller  384  has access to the initial cutting sequence and the extraction heights, the controller  384  controls the shearer  300  such that the shearer  300  automatically replicates the pre-defined cutting profile until conditions in the mineral seam  217  change. When seam conditions change, an operator of the shearer  300  may override control of the cutters  335 ,  340  while the controller  384  records the new roof/floor horizon as a new cutting profile. 
     Additionally, the cutting profile may define different cutter heights for different sections along the mineral face  216 . For reference purposes, the mineral face  216  may be divided up into sections based on roof supports. For a simple example, the longwall system may include one hundred roof supports along the mineral face  216 , and the cutting profile for a single shearer pass may specify cutter heights every ten roof supports. In this example, ten different cutter heights, one for each section of ten roof supports, would be included in a cutting profile for a single shearer pass to define the cutter heights for the entire wall. The size of the sections (i.e., the number of roof supports per section) may vary depending on the desired precision and other factors. 
       FIG. 12  illustrates a method implemented by the analysis module  434  and the correction module  438  to maintain the shearer  300  operating within desired pitch position parameters. As shown in  FIG. 12 , the analysis module  434  first receives pitch angle information (block  600 ). The pitch angle information is electronic data received from, for example, an operator or user manually inputting data (e.g., via a keyboard, mouse, touch screen, or other user interface), mineral seam modeling software providing the data, data output by a real-time mineral seam monitoring system, a remote supervisor/operator outside of the mine site (e.g., via the remote monitoring system  400 ), a combination thereof, or another source. The pitch angle information includes or is used to calculate a range of desirable pitch angles, which may be defined by a high threshold and a low threshold. 
     In some instances, the pitch angle information received takes the form of a desired pitch angle  504  and a desired pitch angle tolerance  512 . For example, a user may measure a desired pitch angle  504  at the mine site based on the alignment of the mineral seam  217 , and determine an appropriate pitch angle tolerance  512  for the application based on the type of terrain in which the mine is located and the particular shearer  300  operating parameters. The user then inputs the desired pitch angle  504  (e.g., 20°) and the tolerance  512  (e.g., 30°) into the analysis module  434 . In some embodiments, at step  600 , the user enters some of the pitch angle information, and the analysis module  434  obtains the remainder of the pitch angle information from another source. For example, the user inputs the desired pitch angle  504 , but the analysis module  434  accesses the desired pitch angle tolerance  512  from a memory (e.g., of the controller  384  or of the remote monitoring system  400 ) previously stored at a configuration stage or at the time of manufacture. 
     After receipt, the analysis module  434  uses the desired pitch angle  504  and the desired pitch angle tolerance  512  to determine a high pitch threshold  516  and a low pitch threshold  520  to define a desired pitch angle range  508  (block  604 ). To do so, the analysis module  434  first calculates half of the pitch angle tolerance  508 . In the illustrated example, half of the example 30° pitch angle tolerance  508  corresponds to 15°. The analysis module  434  then adds half of the pitch angle tolerance  508  to the desired pitch angle  504  to calculate the high pitch threshold  516 . In the illustrated example, the high pitch threshold  516  is calculated to be 35° (e.g., 20° plus 15°). To calculate the low pitch threshold  520 , the analysis module  434  subtracts half of the pitch angle tolerance  508  from the desired pitch angle  504 . In the illustrated example, the low pitch threshold  520  is calculated to be 5° (e.g., 20° minus 15°). 
     As shown in  FIG. 11 , due to the calculation of the low pitch threshold  520  and the high pitch threshold  516 , the desired pitch angle  504  corresponds to the midpoint between the low pitch threshold  520  and the high pitch threshold  516 . The low pitch threshold  520  and the high pitch threshold  516  thereby define the desired pitch angle range  508 . In the illustrated example, the desired pitch angle range  508  is 5° to 35°. In some embodiments, the analysis module  434  does not calculate the high pitch threshold  516  and/or the low pitch threshold  520 . Rather, the pitch angle information received by the analysis module  434  includes the high pitch threshold  516  and the low pitch threshold  520 , in addition to or in place of the desired pitch angle  504  and the desired pitch angle tolerance  512 . 
     The analysis module  434  then receives the current pitch angle  500  from the pitch and roll sensor  380  (block  608 ). The analysis module  434  proceeds to determine whether the current pitch angle  500  is within the desired pitch angle range  508 . To do so, the analysis module  434  determines whether the current pitch angle  500  exceeds the high pitch threshold  516  (block  612 ). If the analysis module  434  determines that the current pitch angle  500  exceeds the high pitch threshold  516 , the correction module  438  proceeds to calculate a pitch correction height (block  616 ). The pitch correction height indicates a desired vertical position of the floor cutter  340  that will cause the pitch of the shearer  300  to approach the desired pitch angle  504  and/or operate within the desired pitch angle range  508 . The correction module  438  determines the pitch correction height by calculating the difference between the current pitch angle  500  and the closest pitch threshold  516 ,  520 , translating the angular change to a change in vertical position of the floor cutter  340  (e.g., −0.5 m), and determining the desired vertical position of the floor cutter  340  (e.g., 0 m, down from the current vertical position of 0.5 m). 
     In the illustrated example, when the current pitch angle  500  exceeds the high pitch threshold  516 , the correction module  438  calculates the difference between the current pitch angle  500  and the high pitch threshold  516 , and translates that to a change in vertical position of the floor cutter  340  (e.g., −0.5 m). The correction module  438  then determines the desired vertical position of the floor cutter  340  corresponding to the change in vertical position needed to induce the calculated change in pitch angle. For example, the correction module  438  may determine that to bring the pitch angle of the shearer  300  within the desired pitch angle range  508 , the floor cutter  340  should be moved to a desired vertical position of, for example, 0 m, down from the current vertical position of 0.5 m. The correction module  438  communicates with the left arm hydraulic system  388  to change the vertical position of the floor cutter  340  such that the left arm hydraulic system  388  lowers the floor cutter  340  to the pitch correction height (e.g., the desired vertical position of the floor cutter  340 ) at block  620 . Once the floor cutter  340  is lowered and the AFC  215  is advanced forward, the pitch angle of the shearer  300  decreases on the next pass and begins operating within the desired pitch angle range  508 . The analysis module  434  then continues to monitor the pitch angle of the shearer  300  (block  608 ). 
     If, on the other hand, the analysis module  434  determines that the current pitch angle  500  does not exceed the high pitch threshold  516 , the analysis module  434  proceeds to determine if the current pitch angle  500  is below the low pitch threshold  520  (block  624 ). If the analysis module  434  determines that the current pitch angle  500  is below the low pitch threshold  520 , the correction module  438  proceeds to calculate the pitch correction height. In this instance, the correction module  438  determines the pitch correction height by calculating the difference between the current pitch angle  500  and the low pitch threshold  520 , translating the angular difference to a necessary change in height, and determining the desired vertical position of the floor cutter  340 . The correction module  438  communicates with the left arm hydraulic system  388  to change the vertical position of the floor cutter  340  such that the left arm hydraulic system  388  raises the floor cutter  340  to the pitch correction height (block  632 ). Once the floor cutter  340  is raised to the desired vertical position of, for example, 1 m, and the AFC  215  advances forward, the pitch angle of the shearer  300  also increases on the next pass and begins operating within the desired pitch angle range  508 . The analysis module  434  then continues to monitor the pitch angle of the shearer  300  (block  608 ). If, on the other hand, the analysis module  434  determines that the current pitch angle  500  is not below the low pitch threshold  520  (i.e., the current pitch angle  500  is within the desired pitch angle range  508 ), the analysis module  434  simply continues to monitor the current pitch angle  500  with respect to the desired pitch angle range  508  and the position of the floor cutter  340  is not changed. 
     In general, the more the current pitch angle  500  exceeds the high pitch threshold  516 , or is below the low pitch threshold  520 , the larger the necessary change in vertical position of the floor cutter  340  to correct the pitch angle of the shearer  300 . However, due to the physical dimensions of the shearer  300  (e.g., the length of the cutter arms  315 ,  320 ) and the AFC  215  (e.g., the depth of the AFC  215 ), the cutters  335 ,  340  may be restricted to a maximum vertical height, for example, 3 m, and a minimum vertical height, for example, −1.0 m. Therefore, the desired vertical positions of the floor cutter  340  do not exceed the maximum vertical height or the minimum vertical height. In other words, even if the correction module  438  calculates the desired vertical position of the floor cutter  340  to be either above the maximum vertical height or below the minimum vertical height, the correction module  438  will determine that the desired vertical position in those situations is equal to the maximum vertical height or the minimum vertical height, as appropriate. In such instances, however, even after the floor cutter  340  is moved to the desired vertical position, the change in vertical position may not be sufficient to bring the shearer  300  into the desired pitch angle  504 . Therefore, in such instances, the pitch angle for the shearer  300  may require more than one pass to correct the pitch angle  500 . 
     The pitch angle detection and corrective action relies in part on the floor cutter  340  trailing the main body of the shearer  300 . In other words, it relies in part on the floor cutter  340  being positioned on the end of the shearer  300  opposite the direction of travel during shearing. Accordingly, when the controller  384  determines that the current pitch angle  500  is outside of the desired pitch angle range  508 , the floor cutter  340  has not yet sheared mineral away from the section of the mineral face  216  in front of the (excessively-pitched) shearer  300 . This arrangement allows the controller  384  to determine if the current pitch angle  500  is within the desired pitch angle range  508 , and adjust the vertical position of the trailing floor cutter  340 , as appropriate, before the floor cutter  340  reaches the relevant section of the mineral face  216 . In such embodiments, the controller  384  continuously monitors the current pitch angle  500  of the shearer  300  and takes corresponding corrective action (lowering/raising the floor cutter  340 ) during a single shearer pass. Before the next shearer pass, the AFC  215  advances forward over the surface that was just sheared with the pitch angle correction techniques. Then, on the next shearer pass, the pitch angle correction is at least partially realized by the shearer  300 , because the AFC  215  is located on the just-sheared surface. 
     The pitch angle of the shearer  300 , however, may operate outside the desired pitch angle range  508  in some sections of the mineral face  216  and operate inside the desired pitch angle range  508  in other sections of the mineral face  216 . Therefore, the controller  384  may change the vertical position of the floor cutter  340  more than once during a single shearer pass. For instance, in one example, the controller  384  determines that the current pitch angle  500  exceeds the high pitch angle threshold  516 , and lowers the floor cutter  340 . The current pitch angle  500  continues to exceed the high pitch angle threshold  516  for, e.g., twenty-five roof supports. Then, the current pitch angle  500  decreases and the shearer  300  operates within the desired pitch angle range  508 . In turn, the controller  384  stops the corrective action by bringing the floor cutter  340  back to its original vertical position or its programmed position. This step of setting the floor cutter  340  to its original or programmed vertical position, while not shown in  FIG. 12 , would occur after detecting that the current pitch angle  500  is within the desired pitch angle range  508  (a “no” decision in step  624 ) and before returning to step  608 . The pitch angle  500  may again be outside of the desirable pitch angle range  508  further along the mineral face  216 . For instance, the current pitch angle  500  may trend below the low pitch threshold, and the controller  384  will then take corrective action by raising the floor cutter  340 . 
     Although the steps in  FIG. 12  are shown as occurring serially, one or more of the steps are executed simultaneously. For example, the analyzing steps of  FIG. 12  may occur simultaneously such that all conditions are checked. Therefore, the controller  384  inhibits the shearer  300  to operate at an inadequate pitch angle and provides corrective action to automatically change the position of the floor cutter to impact the pitch angle of the shearer  300 . The controller  384  may also monitor and control other operations and/or characteristics of the shearer  300 , such as, for example, the speed of the cutters  335 ,  340 , the roll angle, the position of the cutters  335 ,  340  independent of the pitch of the shearer  300 , and the like. Although  FIG. 11  illustrates pitch angle thresholds that are both positive values, in some embodiments, one or both of the pitch threshold is/are negative (e.g., −5°). 
     With reference to the comparisons between the current pitch angle  500  and the pitch angle thresholds  516 ,  520 , “exceeding” means greater than, or means greater than or equal to, and “below” means less than, or means less than or equal to. 
     The extraction system  100  also includes a health monitoring system  400  that monitors general operation of the longwall system  200 . As shown in  FIG. 13 , the health monitoring system  400  includes longwall control system  405 , a surface computer  410 , a network switch  415 , a monitoring system  420 , and a service center  425 . In the illustrated embodiment, the longwall control systems  405  are located at the mine site. The longwall control system  405  includes various components and controls for the components of the longwall mining system  200 . For example, the longwall control system  405  may include various components and controls for the shearer  300 , the roof supports  205 , the AFC  215 , and the like. As shown in  FIG. 14 , the longwall control systems  405  include a main controller  475  configured to be in communication with the shearer controller  384 , an AFC controller  406 , and a roof support controller  407 . In other embodiments, the longwall control systems  405  are configured such that the main controller  475  communicates directly with sensors and systems relevant to the AFC  215 , the roof support  205 , and the shearer  300 . In such embodiments, the shearer controller  384  may be omitted and the sensors  360 ,  365 ,  370 ,  375 ,  380 , the hydraulic systems  386 ,  388 , and the cutter motors  350 ,  355  communicate directly with the main controller  475 . 
     As shown in  FIG. 13 , the longwall control systems  405  are in communication with the surface computer  410  via the network switch  415 , both of which can also be located at the mine site. Data from the longwall control system  405  is communicated to the surface computer  410 , such that, for example, the network switch  415  receives and routes data from the controller  475  and/or the individual control systems of the shearer  300 , the roof supports  205 , and the AFC  215 . The surface computer  410  is in further communication with a remote monitoring system  420 , which can include various computing devices and processors  421  for processing data received from the surface computer  410  (such as the data communicated between the surface computer  410  and the various longwall control systems  405 ), as well as various servers  423  or databases for storing such data. The remote monitoring system  420  processes and archives the data from the surface computer  410  based on control logic that can be executed by one or more computing devices or processors  421  of the remote monitoring system  420 . The particular control logic executed at the remote monitoring system  420  can include various methods for processing data from each mining system component (i.e., the roof supports  205 , the AFC  215 , shearer  300 , and the like). The remote monitoring system  420  applies stored rules and algorithms to the data received from the surface computer  410  to determine if the longwall system  200  operates within specified parameters. If the remote monitoring system  420  determines that the longwall system  200  does not operate within specified parameters, the remote monitoring system  420  may flag the occurrence as an event and generate an alert. In some embodiments, the remote monitoring system  420  may communicate with the service center  425  to notify the service center  425  of the operation of the longwall system  200 . A user can also contact the service center  425  directly to inquire about a specific longwall system  200 . 
     Each of the components of the health monitoring system  400  is communicatively coupled for bi-directional communication. The communication paths between any two components of the health monitoring system  400  may be wired (e.g., via Ethernet cables or otherwise), wireless (e.g., via a WiFi®, cellular, Bluetooth® protocols), or a combination thereof. Although only an underground longwall mining system  200  and a single network switch  415  is depicted in  FIG. 13 , additional mining machines both underground and surface-related (and alternative to longwall mining) may be coupled to the surface computer  410  via the network switch  415 . Similarly, additional network switches  415  or connections may be included to provide alternate communication paths between the underground longwall control systems  405  and the surface computer  410 , as well as other systems. Furthermore, additional surface computers  410 , remote monitoring systems  420 , and service centers  425  may be included in the health monitoring system  400 . 
     As explained above, the controller  475  receives information regarding the various components of the longwall mining system  200 . The controller  475  can aggregate the received data and store the aggregated data in a memory, including a memory dedicated to the controller  475 . Periodically, the aggregated data is output as a data file via the network switch  415  to the surface computer  410 . From the surface computer  410 , the data is communicated to the remote monitoring system  420 , where the data is processed and stored according to control logic particular for analyzing data aggregated since the previous data file was sent. The aggregated data may also be time-stamped based on the time the sensors  360 ,  365 ,  370 ,  375 ,  380  and other sensors from the longwall system  200  obtained the data. The data can then be organized based on the time it was obtained. For example, a new data file with sensor data may be sent every three minutes. The data file includes sensor data aggregated over the previous three minute window. In some embodiments, the time window for aggregating data can corresponds to the time required to complete one shearer cycle. In some embodiments, the controller  475  does not aggregate data, but rather the controller  475  sends data as it is received in real-time. In such embodiments, the remote monitoring system  420  is configured to aggregate the data as it is received from the controller  475 . The remote monitoring system  420  can then analyze the shearer data based on stored aggregated data, or based on horizon control data received in real-time from the controller  475 . 
     In some embodiments, the remote monitoring system  420 , in particular the remote processor  421 , also generates an alert or alarm when the shearer  300  operates outside of specified parameters. For example, the alarm or alert may include general information about the event including, for example, when the event occurred, a location of the event, an indication of the parameter associated with the event (e.g., shearer pitch angle and floor cutter position), and when the event/alert was created. The alert can be archived in the remote monitoring system  420  or exported to the service center  425  or elsewhere. For example, the remote monitoring system  420  can archive alerts that are later exported for reporting purposes. The alert may take several forms (e.g., e-mail, SMS messaging, etc.). In the illustrated embodiment, the alert is an e-mail message as shown in  FIG. 15 . In the illustrated embodiment, the e-mail alert  530  includes text  534  with general information about the alert. In some embodiments, the e-mail alert  530  may also include an attached image file  538 . In the illustrated embodiment, the attached image file  538  is a Portable Network Graphic (.png) file, including a graphic depiction of the operation of the shearer  300  as the shearer  300  shears mineral from the mineral face  216 . 
     It should be understood that while the controller  384  of the shearer  300  was described as performing the functionality with regard to monitoring the pitch position of the shearer  300 , in some embodiments, the health monitoring system  400  monitors the pitch position of the shearer  300  and sends instructions to the shearer  384  regarding the change in position of the floor cutter  340 . In such embodiments, the controller  384  of the shearer  300  may serve to route information to the longwall control system  405  and then to the remote monitoring processor  421 . The remote monitoring processor  421  then executes the method shown in  FIG. 12 , and sends instructions back to the controller  384  to change the position of the floor cutter  340  in a specified manner. 
     In yet other embodiments, the longwall controller  475  performs the monitoring of the pitch position of the shearer  300 . Again, in such embodiments, the controller  384  of the shearer  300  routes data from the sensors  360 ,  365 ,  370 ,  375 ,  380  to the longwall controller  475 . The longwall controller  475  determines the corrective action (i.e., if the position of the floor cutter  340  needs to change) and sends instructions to the controller  384  of the shearer  300  to change the position of the floor cutter  340 , if needed. In yet other embodiments, the controller  384  of the shearer  300  may be omitted, and the health monitoring system  400 , for example, the longwall controller  475 , the remote monitoring processor  421 , or a combination thereof, monitor the pitch position of the shearer as described with respect to  FIGS. 11 and 12 . 
     It should also be noted that the remote monitoring system  420  may run analyses described with respect to the pitch angle, as well as other analyses, whether these analyses are conducted on horizon data or other longwall component system data. The analyses can be executed by either the processor  421  or another designated processor of the health monitoring system  400 . For example the remote monitoring system  420  may run analyses on monitored parameters (collected data) from other components of the longwall mining system  200 . In some instances, for example, the remote monitoring system  420  performs other analyses on data collected form the sensors  360 ,  365 ,  370 ,  375 ,  380  and generates alerts. Such alerts can include detailed information regarding a situation that triggers the alert. 
     Thus, the invention provides, among other things, systems and method for monitoring the pitch angle of a shearer in a longwall mining system. Various features and advantages of the invention are set forth in the following claims.