Patent Publication Number: US-10767481-B2

Title: Self-advancing roof support for a longwall mining system

Description:
TECHNICAL FIELD 
     The present disclosure relates to a self-advancing roof support for a longwall mining system. More particularly, the present disclosure relates to a control system for autonomously controlling movement of a roof support that is associated with a longwall mining system. 
     BACKGROUND 
     Longwall mining systems have typically been using roof supports for controlling a roof of an underground mine. These systems use a moving longwall shearer to cut out a portion of a seam that is located in front of the shearer. However, if poor geological conditions exist when the shearer cuts out a portion of the seam, a cavity could form in a portion of the roof that is between an anterior region of the roof support and the forwardly located seam. This cavity may pose risk to mine and operator safety as it exposes the mine and the operator/s to a potential risk of the roof collapsing over. It would be prudent to provide support beneath an exposed cavity as soon as possible so that both mine and operator safety can be ensured at all times when undertaking mining activity. 
     However, as operators of the longwall mining system are typically tasked with the activity of noticing deformities in the coal seam, such as cavity formations in the roof of an underground mine, the operators may suffer from fatigue owing to manual intervention in the process of detecting these deformities. Moreover, the operator&#39;s intuition and judgement process in detecting these deformities cannot be fully relied upon. When detecting the presence of cavities, the operator&#39;s judgement could be less than accurate, more than adequately erroneous, or delayed due to which the operator would not be able to mitigate the factor of risk to both mine and operator safety. 
     Hence, there is a need for a roof support for a longwall mining system that overcomes the aforementioned drawbacks and provides improved mine and operator safety. 
     SUMMARY OF THE DISCLOSURE 
     In an aspect of the present disclosure, a control system is provided for autonomously controlling movement of a roof support associated with a longwall mining system. The roof support has a base, at least one hydraulic actuator whose one end is pivotally coupled to the base, and a canopy portion that is connected to another end of the hydraulic actuator and pivotally coupled to the base by an intermediate pivoting link member. The control system includes at least one load sensor disposed on the canopy portion. The at least one load sensor is configured to generate a signal indicative of an amount of load borne by the canopy portion in abutment with a roof of an underground mine site. The control system also includes a controller that is communicably coupled to the at least one load sensor and the at least one hydraulic actuator of the roof support. The controller is configured to determine if the signal indicative of the amount of the load borne by the canopy portion is suggestive of a cavity adjacent to a zone above the canopy portion. Based on the determination, the controller is configured to actuate movement of the at least one hydraulic actuator for causing movement of the roof support such that the canopy portion is displaced into a position underlying the cavity. 
     In another aspect of the present disclosure, a self-advancing roof support for a longwall mining system includes a base, at least one hydraulic actuator having one end pivotally coupled to the base, and a canopy portion that is connected to another end of the hydraulic actuator and pivotally coupled to the base by an intermediate pivoting link member. The self-advancing roof support also includes at least one load sensor disposed on the canopy portion. The at least one load sensor is configured to generate a signal indicative of an amount of load borne by the canopy portion in abutment with a roof of an underground mine site. The self-advancing roof support further includes a controller that is communicably coupled to the at least one load sensor and the at least one hydraulic actuator of the roof support. The controller is configured to determine if the signal indicative of the amount of the load borne by the canopy portion is suggestive of a cavity adjacent to a zone above the canopy portion. Based on the determination, the controller is configured to actuate movement of the at least one hydraulic actuator for causing movement of the roof support such that the canopy portion is displaced into a position underlying the cavity. 
     In yet another aspect of the present disclosure, a method is provided for autonomously controlling movement of a roof support associated with a longwall mining system. The roof support has a base, at least one hydraulic actuator having one end pivotally coupled to the base, and a canopy portion connected to another end of the hydraulic actuator and pivotally coupled to the base by an intermediate pivoting link member. The method includes generating, using at least one load sensor disposed on the canopy portion, a signal indicative of an amount of load borne by the canopy portion in abutment with a roof of an underground mine site. The method further includes receiving, by means of a controller communicably coupled to the at least one load sensor, the signal indicative of the amount of load borne by the canopy portion in abutment with the roof of the underground mine site. The method also includes determining, by means of the controller, if the signal indicative of the amount of the load borne by the canopy portion is suggestive of a cavity adjacent to a zone above the canopy portion. Based on the determination, the method also includes actuating movement of the at least one hydraulic actuator, by means of the controller, for causing movement of the roof support such that the canopy portion is displaced into a position underlying the cavity. 
     Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a self-advancing roof support for a longwall mining system, in accordance with an embodiment of the present disclosure; 
         FIG. 2  is a top perspective view of the self-advancing roof support showing schematically a control system having multiple load sensors positioned on a canopy portion of the roof support and a controller coupled to the load sensors and a hydraulic actuator of the roof support, according to an embodiment of the present disclosure; 
         FIG. 3  is a side view of the self-advancing roof support showing an end of the canopy portion in a position adjacent to a cavity in a roof of the mine, according to an exemplary embodiment of the present disclosure; and 
         FIG. 4  is a flowchart of a method for autonomously controlling movement of the roof support, according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to specific aspects or features, examples of which are illustrated in the accompanying drawings. Wherever possible, corresponding or similar reference numbers will be used throughout the drawings to refer to the same or corresponding parts. With reference to the drawings, the claims, and the specification, the present disclosure is directed to a self-advancing roof support for a longwall mining system. More particularly, the present disclosure relates to a control system for autonomously controlling movement of a roof support that is associated with a longwall mining system. 
     Referring to  FIGS. 1, 2 and 3 , a self-advancing roof support  102  (hereinafter referred to as “the roof support  102 ” and denoted by identical numeral “102”) for a longwall mining system  100  is depicted. As shown, the roof support  102  has a base  104 . The base  104  would typically be supported on a floor  108  of an underground mine site  106  as shown in the exemplary view of  FIG. 3 . 
     The roof support  102  also includes at least one hydraulic actuator  110 . As shown in the illustrated embodiment of  FIGS. 1, 2, and 3 , the at least one hydraulic actuator  110  disclosed herein is embodied in the form of a primary hydraulic actuator  112  whose one end  112   a  is pivotally coupled to the base  104  and another end  112   b  is pivotally coupled to a canopy portion  114  of the roof support  102 . Moreover, as shown, the canopy portion  114  is also pivotally coupled to an intermediate pivoting link member  116  which in turn is pivotally connected to the base  104  by, for example, a pair of links  118  and  120  as shown best in the exemplary views of  FIGS. 1 and 3 . 
     Although this disclosure is hereinafter explained in conjunction with the primary hydraulic actuator  112 , it may be noted that the terms “at least one hydraulic actuator  110 ” is not limited to the primary hydraulic actuator  112  disclosed herein nor is the roof support  102  of the present disclosure limited in configuration to merely include the primary hydraulic actuator  112  alone therein. In alternative embodiments, the roof support  102  disclosed herein may, additionally, or optionally, include other hydraulic actuators, for example, one or more secondary hydraulic actuators (not shown) to actuate movement of specific components of the roof support  102  relative to one another. In one example, the roof support  102  may include one secondary hydraulic actuator between the canopy portion  114  and the intermediate pivoting link member  116  for moving the canopy portion  114  and the intermediate pivoting link member  116  relative to each other. 
     Additionally, or optionally, in another example, the roof support  102  may include another secondary hydraulic actuator, for example, a relay bar cylinder  126  that could be located between a bridge (not shown) formed in an anterior portion of the base  104  and a footing  124  of a relay bar  122  that can be operatively commanded by the controller  206  to push an associated segment of a pan line conveyor (not shown) when the canopy portion  114  is in abutment with the roof  302 , or can alternatively be commanded by the controller  206  to displace the base  104  relative to the footing  124  of the relay bar  122  and hence, the overall roof support  102  from its initial position on the floor  108  in a direction Di underlying the cavity  304  when the canopy portion  116  is away from the roof  302  of the underground mine site  106 . Persons skilled in the art will acknowledge that various configurations of hydraulic actuators may be implemented for use in the roof support  102  of the present disclosure for moving specific components, parts, or portions of the roof support  102  in relation to each other. Therefore, such configurations should be construed as being non-limiting of the present disclosure and falling within the scope of the appended claims for being actuated for movement by the control system  202  disclosed herein, explanation to which will be made hereinafter. 
     The roof support  102  of the present disclosure includes a control system  202 . The control system  202  includes at least one load sensor  204  disposed on the canopy portion  114 . The at least one load sensor  204  is configured to generate a signal indicative of an amount of load borne by the canopy portion  114  when in abutment with a roof  302  of the underground mine site  106 . Explanation hereinafter will be made in conjunction with a singular load sensor  204 . However, it may be noted that such explanation is similarly applicable when multiple load sensors  204  are present, for example, the multiple sensors  204   a ,  204   b , and  204   c  as shown in the view of  FIG. 2 . In fact, it is hereby envisioned that when multiple load sensors  204  are used, it may be possible to accurately locate for e.g., by triangulating a position of a cavity  304  on the roof  302  in relation to one or more load sensors  204   a ,  204   b , and/or  204   c  from the multiple load sensors  204  present on the canopy portion  114 . 
     As shown best in the illustrated embodiment of  FIG. 2 , the at least one load sensor  204  could be located on a top surface  114   a  of the canopy portion  114 . However, in other embodiments, depending on specific requirements of an application, other locations on the canopy portion  114  of the roof support  102  could be suitably selected in lieu of the top surface  114   a  for positioning the at least one load sensor  204  thereon. 
     In an example as shown in the view of  FIG. 2 , the control system  202  includes three load sensors  204   a ,  204   b , and  204   c . In one embodiment, each of these load sensors  204   a ,  204   b , and  204   c  could include a load cell. In an alternative embodiment, each of these load sensors  204   a ,  204   b , and  204   c  could include a strain gauge. Although the load cell and the strain gauge are disclosed herein, such types of load sensors are non-limiting of this disclosure. Persons skilled in the art will acknowledge that the load cell and the strain gauge are just two of many possible configurations of load sensors that are known in the art and other suitable configurations of load sensors known to persons skilled in the art can be readily used to realize functions consistent with the present disclosure. Therefore, it may be noted that other functionally equivalent devices may be implemented as the load sensors  204  for use, in lieu of the load cell or the strain gauge disclosed herein, without deviating from the spirit of the present disclosure. 
     The control system  202  also includes a controller  206  that is communicably coupled to the at least one load sensor  204  and the at least one hydraulic actuator  110 , for example, the primary hydraulic actuator  112  of the roof support  102 . In operation, the controller  206  is configured to receive the signal, indicative of the amount of the load borne by the canopy portion  114 , from the at least load sensor  204  and determine if the signal, indicative of the amount of the load borne by the canopy portion  114 , is suggestive of a cavity  304  adjacent to a zone above the canopy portion  114 . If the controller  206  determines that the signal is suggestive of a cavity  304  adjacent to the zone above the canopy portion  114 , the controller  206  actuates movement of the at least one hydraulic actuator  110  for causing movement of the roof support  100  such that the canopy portion  114  is displaced into a position underlying the cavity  304 . In another embodiment herein, it can also be contemplated that the controller  206  would be configured to actuate movement of the at least one secondary hydraulic actuator, for example, the relay bar cylinder  126  for displacing the base  104  relative to the footing  124  of the relay bar  122  when the canopy portion  114  is away from the roof  302  due to which the overall roof support  102  can be advanced from its initial position on the floor  108  in a direction Di underlying the cavity  304 . 
     It may also be noted that the controller  206  disclosed herein could include various software and/or hardware components configured to perform functions that are consistent with the present disclosure. As such, the controller  206  of the present disclosure may be a stand-alone controller or may be configured to co-operate with an existing electronic control module (ECU) (not shown) of the longwall mining system  100 . Furthermore, it may be noted that the controller  206  may embody a single microprocessor or multiple microprocessors that include components for selectively and independently actuating specific system hardware, for example, pumps, solenoids, valves, and other components that are associated with the at least one hydraulic actuator  110 . 
     As exemplarily shown in the view of  FIG. 3 , the canopy portion  114  is shown displaced into a position underlying the cavity  304 . During operation of the roof support  102  disclosed herein, it may be noted that although not absolutely necessary, it would be preferable if the canopy portion  114  is disposed generally in a horizontal orientation i.e., transverse to a direction D in which gravity acts as orientations other than the horizontal orientation of the canopy portion  114  could be less than optimum in providing an equal and opposite reactionary force for adequately supporting a weight associated with the roof  302  of the underground mine site  106 . However, orientations other than the horizontal orientation are possible, and hence, the horizontal orientation should not be construed as being limiting of the present disclosure. Rather, embodiments of the present disclosure are directed towards supporting the weight of the roof  302  adequately and promptly as soon as the controller  206  determines from the signal output from the at least one load sensor  204  that the load borne by the canopy portion  114  of the roof support  102  is suggestive of a cavity  304  in a zone adjacent to the canopy portion  114 . 
     Further, in an embodiment as shown in  FIG. 2 , a notification device  208  may be communicably coupled to the controller  206 . This notification device  208  may include, for example, a Graphical User Interface having a display device (not shown). In this embodiment, the controller  206  would be configured to notify an operator, via the notification device  208 , of the displacement in the position of the canopy portion  114  relative to the base  104  of the roof support  102 . Additionally, or optionally, if other movements are accomplished by the controller  206 , for example, if the base  104  is displaced relative to the canopy portion  114 , then the controller  206  would also be configured to notify, via the notification device  208 , to the operator, the advance in the position of the base  104  relative to the footing  124  of the relay bar  122  when the canopy portion  114  is away from the roof  302  due to which the overall roof support  102  would be advanced from its initial position on the floor  108  in the direction Di underlying the cavity  304 . 
       FIG. 4  illustrates a flowchart depicting a method  400  for autonomously controlling movement of a roof support  102  associated with a longwall mining system  100 , for example, the roof support  102  of the longwall mining system  100  of  FIG. 1 . As shown, at step  402 , the method  400  includes generating, using the at least one load sensor  204  disposed on the canopy portion  114 , a signal indicative of an amount of load borne by the canopy portion  114  in abutment with the roof  302  of the underground mine site  106 . Further, at step  404 , the method  400  also includes receiving, by the controller  206 , the signal indicative of the amount of load borne by the canopy portion  114  in abutment with the roof  302  of the underground mine site  106 . Further, at step  406 , the method  400  also includes determining, by the controller  206 , if the signal indicative of the amount of load borne by the canopy portion  114  is suggestive of a cavity  304  adjacent to a zone above the canopy portion  114 . Further, at step  408 , the method  400  also includes actuating movement of the at least one hydraulic actuator  110 , by the controller  206 , for causing movement of the roof support  102  such that the canopy portion  114  is displaced into a position underlying the cavity  304 . 
     Also, in embodiments herein, the method  400  further includes notifying the operator, by the controller  206  via the notification device  208 , of the displacement in the position of the canopy portion  114  relative to the base  104 . Additionally, or optionally, if the base  104  has been displaced from its initial position, then the method  400  may further include notifying the operator, by means of the controller  206  via the notification device  208 , of the advance in the position of the base  104  relative to the canopy portion  114 . 
     INDUSTRIAL APPLICABILITY 
     Embodiments of the present disclosure have applicability for use in providing a self-advancing roof support that can autonomously support a roof of an underground mine site. In previously known underground mining practices, operators of longwall mining systems would physically i.e., visually inspect the roof of an underground mine site during operation, and subsequently determine a movement of one or more roof supports based on findings from the inspection process. This process of visual inspection was tedious, time-consuming, and costly. Besides, the resultant manual intervention from operators also increased the possibility of making inaccurate and/or delayed judgements when taking decisions for moving the roof support. Such inaccurate and/or delayed judgements could potentially pose a risk to mine and operator safety, for example, if a deformity such a cavity in the roof of the underground mine site is left exposed and could result in an adjoining portion of the roof to cave in i.e., collapse. 
     With use of the self-advancing roof support disclosed herein, operators of longwall mining systems can be freed up, at least to some extent, from the additional burden and responsibility of having to physically inspect the roof of the underground mine site as mining activity is in progress. Consequently, this could result in a lowering of fatigue that was previously experienced by the operators. Also, the inaccuracies and/or delays in judgements that were incurred with manual intervention from previously known underground mining practices are obviated with the use of the self-advancing roof support of the present disclosure. The self-advancing roof support disclosed herein can autonomously detect not only the presence of a cavity, but also a location of the cavity, and can autonomously move the itself forward to support the roof adjoining the cavity. If movement of other components, for example, the intermediate pivot link member, or any other component is required, the controller disclosed herein would also be configured to move such other components by issuing commands for appropriate movement of the other components. These movements may be commanded by the controller, for execution at respective hydraulic actuators, in a tandem manner so as to represent a sequence of movements or may, alternatively, be executed in a simultaneous manner dictated by other pre-defined logic pre-set at the controller. 
     With implementation of embodiments disclosed herein, the roof support of the present disclosure overcomes the aforementioned drawbacks typically associated with a manual triggering of movement for the roof supports by operators. With a near real-time movement of the canopy portion, upon detection of a cavity in the roof of the underground mine site, the self-advancing roof support can move autonomously to offer prompt and adequate support to the roof. 
     While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed vehicles, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.