Patent Publication Number: US-2016236606-A1

Title: Method for controlling hoisting of an articulated machine

Description:
TECHNICAL FIELD 
     The present disclosure relates to an articulated machine, and more particularly to a system and a method of controlling a hoisting of the articulated machine. 
     BACKGROUND 
     Articulated machines such as articulated trucks with a payload carrier, and ejector mechanisms typically include two frames such as a tractor unit and the payload carrier which is connected to the tractor unit via an articulation joint. The articulation joint enables the frames to roll and yaw with respect to each other. 
     Articulated machines are generally employed during construction and excavation and may be operated on uneven terrains. As a result, one of the frames may be positioned at an unsafe roll and/or yaw angle and may cause the entire machine to roll-over. Alternatively, if the articulated machine has an open container, such as an open carrier on one of the frame, any material in the container may fall out on uneven terrain if the machine operates beyond the maximum allowable operating speed, and safety limits of the roll and yaw angles. Furthermore, since the roll and yaw angles of the frames are independent of each other, the operator may be unaware of the unsafe roll and yaw angles which may result in possible roll over of the machine. 
     Hoisting the payload carrier when the articulated machine is either travelling on a grade, or beyond the safety limits of the roll and yaw angles or having a speed greater than a maximum operating speed limit may result in roll over of the articulated machine. 
     U.S. Pat. No. 7,236,096 discloses a monitoring system. The monitoring system of a dump truck prevents the raising of the cargo bed when the level of lateral tilt exceeds a safe limit, a keyed switch allows for presetting the maximum safe degree of tilt by simple left or right manipulation of the switch, and to switch the display from current level of left or right tilt to the value of the preset limit. 
     Hence, there is a need for improved control methods to control articulated machines. 
     SUMMARY OF THE DISCLOSURE 
     In an aspect of the present disclosure, a method of controlling an articulated machine travelling on a ground surface is provided. The articulated machine includes a first frame and a second frame. The method includes receiving a speed signal indicative of a speed of the articulated machine through a speed sensor by the controller. The method includes receiving an inclination signal indicative of an inclination of the ground surface through an inclination sensor by the controller. The method further includes receiving a payload signal indicative of a payload being carried by the articulated machine through a payload sensor by the controller. Thereafter, the controller controls a hoisting of the second frame relative to the first frame based on at least one of the speed signal, the inclination signal and the payload signal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of an articulated machine in accordance with an embodiment of the present disclosure; 
         FIGS. 2 to 5  illustrate various orientations of the articulated machine in different operating conditions, in accordance with an embodiment of the present disclosure; and 
         FIG. 6  is block diagram illustrating the various inputs being received by a controller to control the articulated machine, in accordance with an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or the like parts. The present disclosure relates to a system and method of controlling a hoisting of an articulated machine to prevent roll over of the articulated machine.  FIG. 1  illustrates an exemplary machine  10  embodied as an articulated tipper truck. In various other embodiments, the machine  10  may be any other type of an articulated machine having a first frame  12  such as a tractor unit and a second frame  14  such as a payload carrier attached to the first frame  12  by a coupling assembly  16 . The first frame  12  and the second frame  14  are moveable relative to each other in multiple directions. In an exemplary embodiment, the coupling assembly  16  may be an articulation joint. 
     The coupling assembly  16  may include a pivot frame coupling (not shown) and a rotational frame coupling (not shown). The pivot frame coupling provides articulated movement or pivoting of the second frame  14  relative to the first frame  12  about a central axis of articulation  18 . The rotational frame coupling provides rotational movement of the second frame  14  relative to the first frame  12  about a longitudinal axis  20 . The coupling assembly  16  may allow each of the first and second frames  12 ,  14  to be oriented at a different yaw angle and/or roll angle with respect to the central axis of articulation  18 . The coupling assembly  16  may further include an actuation mechanism (not shown) configured to control the coupling assembly  16 . In an exemplary aspect of the present disclosure, the actuation mechanism may be hydraulically, or electrically and/or electro-mechanically operated. 
     The machine  10  may further include an engine  22  positioned in an engine compartment  24  and supported on the first frame  12 . The engine  22  may be an internal combustion engine, for example, a petrol engine, a diesel engine, or a gas powered engine. In the illustrated embodiment, an operator cab  26  is mounted on a front end  27  of the first frame  12  of the machine  10 . The operator cab  26  may be located above the engine compartment  24  and extend rearward beyond the engine  22 . In some embodiments, the operator cab  26  may enclose the engine  22  by forming a portion of the engine compartment  24 . In other embodiments, the operator cab  26  may be pivotally mounted to the first frame  12 , such that the operator cab  26  may be tilted to provide an access to the engine  22 . The operator cab  26  houses various machine controls. The operator cab  26  may include a hoist control switch (not shown). The hoist control switch may be used by an operator of the machine  10  to command a hoist operation. The hoist control switch may be any type of a switch such as, but not limited to a push pull switch, a rotary switch, a knob switch etc. 
     The second frame  14  may include a body  28  such as the payload carrier for carrying a load. The body  28  is pivotally connected to a chassis  29  at a pivot point (not shown). During operation of the machine  10 , the body  28  may be lowered or raised, such as to a raised position (shown in dashed lines) with respect to the first frame  12  of the machine  10  by an actuator  30 . The actuator  30  is coupled between the chassis  29  and the second frame  14 . The raised position of the second frame  14  is a tipping position where one end of the second frame  14  is raised from the chassis  29  and the other end remains on the chassis  29 . Thus, the body  28  may eject out any material or the payload when in the raised position. 
     The second frame  14  may include an ejection mechanism (not shown) having an ejector plate (not shown) which slides horizontally from one end of an inside of the body  28  of the second frame  14  towards the other end. A hydraulic actuator or the like may be used to move the ejector plate towards the ejection end of the body  28  of the second frame  14 . Further, a front wheel assembly  32  having a pair of front wheels is configured to provide rolling support to the operator cab  26  and is operably coupled to the first frame  12 . A rear wheel assembly  34  is operably coupled to the second frame  14 . The front wheel assembly  32  and the rear wheel assembly  34  are powered by the engine  22  via a drive train (not shown). 
     Further, the machine  10  may include a number of sensor assemblies associated with the machine  10 . In an exemplary aspect of the present disclosure, the machine  10  may include a first sensor assembly  36  associated with the first frame  12  and a second sensor assembly  38  associated with the second frame  14 . The first and second sensor assemblies  36 ,  38  are configured to provide a position information of the first and the second frames  12 ,  14  respectively. In an exemplary aspect of the present disclosure, the first sensor assembly  36  may act as a reference sensor. For example, the position information of the first and second frames  12 ,  14  may be a relative information of the respective frame with respect to the ground surface on which the machine  10  is operating. 
     The first sensor assembly  36  may be attached to any part of the first frame  12 . The second sensor assembly  38  may be attached close to the pivot point between the body  28  and the chassis  29 . In an exemplary embodiment of the present disclosure, the first and second sensor assemblies  36 ,  38  may include multi-axis inertia sensors configured to determine multi-axis position of the respective frames  12 ,  14 . In various alternative embodiments, the first and second sensor assemblies  36 ,  38  may include any type of sensors capable of determining a pitch, a yaw and/or roll angle of the second frame  14  with respect to the first frame  12 . For example, the first and second sensor assemblies  36 ,  38  may include accelerometer or gyroscope sensors. Further, the first and second sensor assemblies  36 ,  38  may include piezoelectric, capacitive, potentiometric, Hall Effect, magnetorestrictive or any other type microelectromechanical sensors. 
     Generally, the first and second sensor assemblies  36 ,  38  may include a “proof” mass which moves relative to the respective frames  12 ,  14 . A difference in movement between the first and second frames  12 ,  14  and the proof mass is related to its acceleration and may be measured in a number of ways such as capacitively, piezo-electrically, and piezo-resistively. Further, the first and second sensor assemblies  36 ,  38  may measure linear acceleration in X, Y and Z directions and angular velocity about the X, Y and Z axis. Furthermore, the first and second sensor assemblies  36 ,  38  may be configured to provide output signals indicative of the position information of the respective frames  12 ,  14  of the machine  10  based on the measured linear acceleration and the angular velocity of the first and second frames  12 ,  14 . 
     The machine  10  further includes a controller  40  (commonly known as an electronic control module or ECM) which controls various aspects of operational parameters of the machine  10 . The output signals from the first and second sensor assemblies  36 ,  38  are transmitted to the controller  40  and used to calculate relative angles of the members to which the first and second sensor assemblies  36 ,  38  are attached, e.g. an angle of the body  28  relative to the first frame  12 . The calculations may relate to both fore and aft angles (in the lateral direction of the machine  10 ) and side to side (across the transverse direction of the machine  10 ). 
     Referring to  FIG. 6 , the machine  10  includes a payload sensor  42 , a speed sensor  44  and an inclination sensor  46 . The payload sensor  42  may monitor aspects of the suspension of the machine  10  or embody a load cell. The payload sensor  42  may also embody an external input representing weight or another device or method known in the art for determining the weight of the payload and the machine  10 . The payload sensor  42  may provide an output value of the payload in any of the preferred units. The payload sensor  42  provides signals to the controller  40  indicative of the payload being carried by the machine  10 . The speed sensor  44  provides signals to the controller  40  indicative of the speed of the machine  10 . 
     The inclination sensor  46  provides an inclination signal to the controller  40 . The inclination signal is indicative of a grade/inclination of the ground surface on which the machine  10  is travelling. The inclination sensor  46  may embody an accelerometer, an inclinometer, or another sensor known in the art for determining incline, decline, change in elevation, slope, orientation, or grade of the ground surface. The inclination sensor  46  may also embody a global positioning system, an external input regarding grade at the current position of the machine  10 , or an input from the operator of the machine  10 . The grade may be measured as a percentage (%) grade of rise divided by run, with 0% grade being a flat slope of zero and a 100% grade being a steep slope of 1 foot rise over 1 foot run (1/1), or a 45 degree slope. 
       FIGS. 2-5  illustrate some possible orientations of the machine  10  and various angles related to the first and second frames  12 ,  14  during various operating configurations.  FIG. 2  illustrates the machine  10  on an inclined ground surface having an inclination angle ‘α 1 ’ so that the first and second frames  12 ,  14  are in horizontal lateral alignment. The body  28  is in a lowered position. 
       FIG. 3  illustrates the machine  10  travelling on an inclined ground surface having an inclination angle ‘α 1 ’. The body  28  is in the raised position. The first and second frames  12 ,  14  are in horizontal lateral alignment. A hoist angle ‘H’ is defined as an angle of the body  28  relative to the first frame  12 . The hoist angle ‘H’ is calculated as a difference between an angle ‘F 1 ’ of the first frame  12  with the horizontal ground surface and an angle ‘F 2 ’ of the body  28  with the horizontal ground surface. The angles ‘F 1 ’ and ‘F 2 ’ are measured by the first and second sensor assemblies  36 ,  38  respectively. The controller  40  may receive the values of the angles ‘F 1 ’ and ‘F 2 ’ from the first and second sensor assemblies  36 ,  38  and calculate the value of the hoist angle ‘H’. 
       FIG. 4  illustrates the machine  10  with the body  28  in the lowered position. The first and second frames  12 ,  14  are in horizontal transverse alignment and horizontal lateral alignment. The body  28  is tilted sideways at an angle ‘α 2 ’ relative to the first frame  12 . Center of Gravity (CG) of the machine  10  shifts upwards as well as sideways compared to its location when the machine  10  travels on a horizontal ground surface. A roll angle ‘R’ may be defined as the maximum allowable inclination angle for the first and second frames  12 ,  14  of the machine  10  to avoid roll over. The roll angle ‘R’ decreases in this orientation, due to increased risk of roll over. The roll angle ‘R’ decreases further if the body  28  is in the raised position. 
       FIG. 5  illustrates the machine  10  travelling on a surface having a side slope ‘α 3 ’ relative to the horizontal ground surface. The body  28  is in the lowered position. The first and the second frames  12 ,  14  are in horizontal transverse alignment and horizontal lateral alignment. The location of the CG of the machine  10  again shifts upwards as compared to the machine  10  travelling on a horizontal ground surface. Thus, the value of the roll angle ‘R’ is again reduced. Similarly, the roll angle ‘R’ decreases further if the body  28  is in the raised position. 
       FIG. 6  shows a control system  48  for controlling the machine  10 . The control system  48  includes the controller  40 . The controller  40  receives signals from the speed sensor  44  indicative of the speed of the machine  10 . The controller  40  receives signals from the payload sensor  42  indicative of the payload being carried by the machine  10 . The controller  40  receives signals from the inclination sensor  46  indicative of the inclination of the ground surface. The controller  40  may also receive signals from the first and second sensor assemblies  36 ,  38  indicative of angles ‘F 1 ’ and ‘F 2 ’. 
     The controller  40  processes the various received signals to ensure safe operating conditions for the machine  10 . The controller  40  processes the signals received from the speed sensor  44  and determines an operating speed of the machine  10 . The controller  40  may have a pre-stored value of a threshold speed S MAX . Operating speeds of the machine  10  higher than the threshold speed S MAX  may be termed as a higher speed range. Operating speeds of the machine  10  lower than the threshold speed S MAX  may be termed as normal speed range. The controller  40  compares the speed signal received from the speed sensor  44  with the threshold speed S MAX  and determines whether the machine  10  is operating in the higher speed range. If the machine  10  is operating in the higher speed range, the controller prevents the hoist operation. The controller  40  further generates a roll over warning in case the controller  40  prevents the hoist operation. 
     The controller  40  receives signals from the inclination sensor  46  indicative of the inclination of the ground surface while the machine  10  is travelling on an inclined surface as shown in  FIGS. 2 and 3 . The controller  40  may also receive signals from the first and second sensor assemblies  36 ,  38  indicative of angles ‘F 1 ’ and ‘F 2 ’. The controller  40  processes the signals received from the first and second sensor assemblies  36 ,  38  to calculate the value of the hoist angle ‘H’. The controller  40  may receive a hoist command from the operator of the machine  10  through the hoist control switch. The hoist command may indicate a desired value of the hoist angle ‘H’. The controller  40  receives signals from the inclination sensor  46  indicative of the inclination of the ground surface. The controller  40  may limit the hoisting of the machine  10  depending upon the inclination signal. For example, the machine  10  may be travelling on an inclined surface having an inclination angle ‘α 1 ’ as shown in  FIG. 3 . The operator may command the hoist operation. The value of the hoist angle ‘H’ may be provided as ‘H 1 ’ by the operator. The controller  40  may limit the hoist angle ‘H’ of the machine  10  and may allow hoisting of the body  28  only up to angle ‘H 1 ’−‘α 1 ’. The controller  40  further generates a roll over warning in case the controller  40  limits the hoist operation. 
     Referring back to  FIGS. 4 &amp; 5 , the machine  10  is shown travelling on a side slope ‘α 3 ’. The controller  40  may receive signals from the inclination sensor  46  indicating the side slope of the ground surface. Additionally, the controller  40  also receives signals from the first and second sensor assemblies  36 ,  38  indicating the inclination ‘F 1 ’ of the first frame  12  and the inclination ‘F 2 ’ of the second frame  14  relative to the horizontal ground surface. The controller  40  compares the angles ‘F 1 ’ and ‘F 2 ’ with the roll angle ‘R’. The controller  40  may generate a roll over warning in case inclination of the first frame  12  or the second frame  14  exceeds the roll angle ‘R’. Further, the controller also receives signals indicative of the payload of the machine  10 . As explained in the description of  FIG. 5 , the location of the CG of the machine  10  shifts upwards as compared to when the machine  10  is travelling on a horizontal ground surface. Further, a hoist operation in this orientation may cause the CG of the machine  10  to shift further upwards and that may cause the roll angle ‘R’ threshold to decrease. The controller  40  determines whether the hoisting of the second frame  14  to the desired angle can be completed without reaching the roll angle R. If the controller  40  identifies that the hoisting of the second frame  14  to the desired angle cannot be completed and the roll over event may occur, then the controller  40  prevents the hoisting of the second frame  14 . 
     The roll over warning may be an audible signal provided to the operator in the operator cab  26 . The roll over warning may be a video signal provided to the operator in the operator cab  26  on the display screen. The roll over warning may be provided by any other means without departing from the scope of the present disclosure. The roll over warning is active for a period for which the operational parameters of the machine  10  suggest a possible roll over condition. 
     The controller  40  may also provide a notification to the operator in the operator cab  26  in case the hoist is controlled by the controller  40 . The operator may have an option to override the hoist prevention or limiting by the controller  40 . For example, the operator may be prompted on the display screen to accept or reject the actions of the controller  40  to control the hoist operation. The operator may override the hoist control by selecting a center position of the hoist control switch and may manually reset the values for maximum allowable hoist angle. 
     However, in case the machine  10  encounters a roll over event, such as when the operator of the machine  10  continues to operate outside the safety limits as indicated by the warnings displayed by the controller  40  on the display screen, then the controller  40  may store the details of the roll over event in a database. For example, the controller  40  may store the date, time, name of the machine  10  and type etc., associated with the roll over event. 
     INDUSTRIAL APPLICABILITY 
     The controller  40  of the present disclosure receives various signals indicative of operational parameters of the machine  10 . The signals are indicative of the payload carried by the machine  10 , the inclination of the ground surface, the speed of the machine  10  and the relative orientation of the first and second frames  12 ,  14 . The controller  40  processes the various signals and generates warnings at various operating conditions. The warnings are indicative of a possible roll-over of the machine  10 . The operator may judiciously follow/ignore the warnings and continue to safely operate the machine  10 . The controller  40  provides inputs such as to prevent or limit the hoisting of the body  28  relative to the first frame  12 . The warnings may be audible or may be displayed on the display screen in the operator cab  26 . Further, in case the operator chose to ignore the warnings provided by the controller  40  and a roll over occurs, the controller  40  logs various parameters related to the roll over event in the memory of the controller  40 . 
     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 machines, 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.