Patent Publication Number: US-2023134006-A1

Title: System and method of operating a mobile industrial machine

Description:
TECHNICAL FIELD 
     The present disclosure relates generally to operating a mobile industrial machine, and more particularly, to a mobile industrial machine having an electric motor and a hydraulic motor driving a common load. 
     BACKGROUND 
     A paver machine may be a mobile industrial machine that lays asphalt. A front of the paver machine may have a hopper to store asphalt. A conveyor may transport asphalt from the hopper to an auger, which may rotate to spread the asphalt on a ground surface. A rear of the paver machine may include a screed to smooth the laid asphalt. Large torque loads may exist when starting to drive the conveyor (e.g., in cold weather or to unbind or break up hardened asphalt), and/or when the first dump of asphalt is provided to the machine. 
     U.S. Pat. No. 10,718,100, issued on Jul. 21, 2020 (“the &#39;100 patent”), describes a hydraulic system for a feed delivery unit. The hydraulic system may include a plurality of hydraulic motors fluidly coupled to a pump and each configured to drive a respective auger of the feed delivery unit. The plurality of hydraulic motors may be connected in series. 
     Methods and systems of the present disclosure may solve one or more problems in the art. The scope of the current disclosure, however, is defined by the attached claims, and not by the ability to solve any specific problem. 
     SUMMARY 
     In one aspect, a method of operating a mobile industrial machine including an electric motor and a hydraulic motor for driving a common load may include receiving a desired drive request for the electric motor to drive the common load, driving the electric motor based on the desired drive request, sensing that the electric motor is unable to provide the full amount of the desired drive request, and driving the hydraulic motor to fulfill the full amount of the desired drive request. The driving of the hydraulic motor may be a function of an amount of the desired drive request the electric motor is unable to provide. 
     The method may further include sensing that the electric motor is able to provide the full amount of the desired drive request and discontinuing the driving of the hydraulic motor. Driving the electric motor may drive a shaft, and driving the hydraulic motor may drive the shaft to add torque to the shaft. The desired drive request may be an electric motor speed request. The hydraulic motor may be a fixed displacement motor. The electric motor may be rated to be unable to meet all desired drive requests. 
     The mobile industrial machine may be a paver machine, and the common load may be a driven component of a paver machine. The driven component may be a conveyor of the paver machine. 
     In another aspect, a method of operating a mobile industrial machine including an electric motor and a hydraulic motor for driving a common load may include receiving a desired drive request to drive the common load, determining that the electric motor is unable to drive the common load according to the desired drive request, and driving the electric motor and the hydraulic motor to rotate an output shaft coupled to the common load according to the desired drive request. 
     Determining that the electric motor is unable to fulfil the desired drive request may include determining that a maximum rotational speed of the electric motor is unable to rotate the output shaft according to the desired drive request. Determining that the electric motor is unable to fulfil the desired drive request may include receiving a rotational speed of the electric motor and determining that the received rotational speed is unable to rotate the output shaft according to the desired drive request. 
     The mobile industrial machine may be a paver machine, and the common load may be a driven component of the paver machine. The driven component may be a conveyor of the paver machine. 
     The method may further include receiving an additional desired drive request, determining that the electric motor is able to drive the common load according to the additional desired drive request, and discontinuing the driving of the hydraulic motor. Driving the hydraulic motor may include varying a speed of the hydraulic motor. 
     In another aspect, a control system may be configured to control driving a common load of a mobile industrial machine including an electric motor and a hydraulic motor for driving the common load. The system may include a controller configured to receive a desired drive request for the electric motor to drive the common load, drive the electric motor based on the desired drive request, sense that the electric motor is unable to provide the full amount of the desired drive request, and drive the hydraulic motor to fulfill the full amount of the desired drive request. 
     The system may include a user interface. The desired request may be received from the user interface. The mobile industrial machine may be a paver machine. The common load may be a driven component of a paver machine. The driven component may be a conveyor configured to transport asphalt. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate various exemplary embodiments and together with the description, serve to explain the principles of the disclosed embodiments. 
         FIG.  1    schematically illustrates a mobile industrial machine in the form of a paver machine having a conveyor drive system, according to aspects of the disclosure. 
         FIG.  2    is a schematic diagram illustrating a controller of the paver machine of  FIG.  1   . 
         FIG.  3    provides a flowchart depicting an exemplary method for operating the paver machine of  FIG.  1   . 
     
    
    
     DETAILED DESCRIPTION 
     Both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the features, as claimed. As used herein, the terms “comprises,” “comprising,” “has,” “having,” “includes,” “including,” or other variations thereof, are intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements, but may include other elements not expressly listed or inherent to such a process, method, article, or apparatus. In this disclosure, unless stated otherwise, relative terms, such as, for example, “about,” “substantially,” and “approximately” are used to indicate a possible variation of ±10% in the stated value. 
       FIG.  1    illustrates a mobile industrial machine  10 . The mobile industrial machine  10  could be any industrial machine  10  which moves or is propelled by an engine, such as a compactor, tractor, wheel loader, paver, back hoe loader, etc. For convenience of description, the mobile industrial machine  10  will be described herein as a paver machine  10 . 
     The paver machine  10  may include components such as a conveyor  110 , an auger (not shown), a hopper (not shown), a screed  120 , and an operator cabin (not shown), and the paver machine  10  may further include a conveyor drive system  200  to drive the conveyor  110 . The conveyor drive system  200  may include an electric motor system  210  driven by a power source  212  (e.g., battery) and a hydraulic motor system  250 . A controller  310  may control the conveyor driver system  200  based on, among other things, operator commands from a user interface  320  provided in the operator cabin. 
     The conveyor  110  may receive asphalt from the hopper and transport asphalt or other paving material from the hopper to the auger. The hopper may store and/or dispense asphalt or other paving material, and the auger may be a rod formed with a spiral propeller which rotates to spread the asphalt. The screed  120  may further heat and smooth the asphalt down on the ground. 
     The conveyor  110  may be driven by the conveyor drive system  200  to transport asphalt from the hopper to the auger. The conveyor  110  may include a conveyor belt  112 , a pair of conveyor wheels or rollers  114 ,  116 , and a chain, belt, or other drive connection  118 . 
     The conveyor belt  112  may be a closed loop rotating around the pair of conveyor rollers  114 ,  116  to transport asphalt. The pair of conveyor rollers  114 ,  116  may include a driven wheel or roller  114  and a passive wheel or roller  116 . Alternatively, both rollers  114 ,  116  may be driven. The drive roller  114  and the passive roller  116  may be provided at opposite sides of the conveyor belt  112  to support the conveyor belt  112  and/or maintain a tension of the conveyor belt  112 . The chain  118  may couple the driven roller  114  to the conveyor drive system  200  such that the electric motor system  210  and the hydraulic motor system  250  drive the conveyor  110  via the chain  118  and driven roller  114 . It is understood that other connections  118  are possible, including direct shaft couplings. 
     As noted above, conveyor drive system  200  may include the electric motor system  210 , the hydraulic motor system  250 , and an output shaft  290 . The electric motor system  210  and the hydraulic motor system  250  may be combined in parallel. The electric drive system  210 , connected to battery  212 , may primarily drive the conveyor  110 . The electric drive system  210  may include the battery  212 , an electric motor controller  214 , and an electric motor  216 . 
     The battery  212  may power the electric motor controller  214  and the electric motor  216 . Although a battery  212  is described as being the power source for the electric motor  216 , alternatively, other electric power sources (e.g., a fuel cell, internal combustion engine generator, etc.) may be used in place of or in addition to battery  212 . The electric motor controller  214  may be connected to the controller  310  to exchange data back and forth, including receiving commands from the controller  310  for control and operation of the electric motor  216 . The electric motor controller  214  may form a part of electric motor  216  and may include a printed circuit board (PCB) and other controller hardware (e.g., communication module, memory, storage, etc.). 
     The electric motor  216  may rotate the output shaft  290  to drive the conveyor  110 . The electric motor  216  may be a permanent magnet motor, an inverter drive, an alternating current (AC) induction motor having a rotor and stator (not shown), etc. The electric motor controller  214  may include an AC/DC converter, but aspects disclosed herein are not limited. The electric motor  216  may have a variable speed. The electric motor  216  may be limited in a speed or rotational speed (e.g., rotations per minute (rpm)), output torque, and/or a power produced, and/or may be rated as being unable to meet all possible torque loads of the conveyor  110 , and or desired speed requests received from the user interface  320  and/or received from the controller  310  and electric motor controller  214  in connection with the conveyor  110 . For example, the electric motor  216  may have a peak or maximum horsepower or output torque which is insufficient to initially start the conveyor  110 , due to the need to unbind or break up hardened asphalt, or during a first dump of asphalt into the hopper and received on the conveyor  110 , or when there may otherwise be a higher load on the conveyor  110  (e.g., by a weight of asphalt, friction, etc.) 
     The hydraulic motor system  250  may assist a driving of the conveyor  110 . The hydraulic motor system  250  may include a hydraulic circuit  252  and a hydraulic motor  254 . The hydraulic circuit  252  may be connected to the controller  310  and the hydraulic motor  254  to control the hydraulic motor  254 . The hydraulic circuit  252  may include, for example, a pump  253  configured to pump hydraulic fluid and a valve (not shown), for example, a proportional control solenoid driven valve, or other type of controllable valve, etc. to control a flow of the hydraulic fluid to the hydraulic motor  254 . The hydraulic circuit  252  may be a dedicated circuit for driving hydraulic motor  254 , or may be part of a larger hydraulic circuit providing pressurized hydraulic fluid to other systems of the paver machine  10 . The hydraulic circuit  252  may be a closed-loop hydraulic circuit or an open-loop hydraulic circuit. 
     The hydraulic motor  254  may be a variable displacement motor (e.g., with pistons which receive hydraulic fluid from the pump  253  in the hydraulic circuit  252 ) to provide a range of assistive force, torque, or power. The hydraulic motor  254  may be connected to the output shaft  290  to assist the electric motor  216  in driving the output shaft  290 . For example, the hydraulic motor  254  may have a driven shaft rigidly coupled to or integral with the output shaft  290 . The hydraulic motor  254  may provide an additive force, torque, power, or speed to a total force, torque, power, or speed applied to the output shaft  290 . The hydraulic motor  254  may have a free-wheeling connection to the output shaft  290  such that the hydraulic motor  254  may freely rotate with the output shaft  290  when fluid is not applied. As an example, the hydraulic motor  254  may be a radial piston free-wheeling motor. Alternatively or in addition thereto, the hydraulic motor  254  may be configured to engage with and disengage from (e.g., via a slip or sprag clutch) the electric motor  216  and/or the output shaft  290 . As an alternative to a variable displacement motor, the hydraulic motor  254  may be a fixed displacement motor configured to provide a torque to maintain a desired speed. When the hydraulic motor  254  is a fixed displacement motor, the pump  253  of the hydraulic circuit  252  may be a variable displacement pump. 
     The output shaft  290  may be connected to the chain  118  to drive the conveyor  110 , e.g. via a pair of sprockets on the output shaft  290  and a shaft of the driven roller  114 , respectively. As will be described in more detail below, the output shaft  290  may be driven by the electric motor  216 , and selectively additionally driven by the hydraulic motor  254  when the loads require additional drive torque. Thus, conveyor  110  may provide a common load driven by both the electric motor  216  and the hydraulic motor  254 . 
     Referring to  FIGS.  1 - 2   , the controller  310  may be connected to the electric motor controller  214  and the hydraulic circuit  252  to control the electric motor  216  and the hydraulic motor  254 . The controller  310  may receive a plurality of inputs  332 ,  334 , transmit at least one electric motor output  338  to the electric motor controller  214 , and transmit at least one hydraulic motor output  336  to the hydraulic circuit  252 . 
     The plurality of inputs  332 ,  334  may include a desired drive request  332  and an electric motor value  334 . The desired drive request  332  may indicate a desired speed (e.g., rpm) of the conveyor drive system  200  (or alternatively, the shaft  290 , conveyor belt  112 , driven wheel  114 , or the electric motor  216 ) to drive the conveyor  110 . The desired drive request  332  may be (or be calculated from) an input from a user at the user interface  320  ( FIG.  1   ) to control the conveyor  110 . For example, the user may input a desired speed to drive the conveyor  110  into the user interface  320 , which may be indicated by the desired drive request  332 . As another example, the user may press an “on” button to start the conveyor  110 , which may be converted to a desired drive request  332  indicating a determined or required force, torque, speed, or power to drive the conveyor  110 . For convenience of description, the desired drive request  332  transmitted to the controller  310  will be described as a desired speed request, which may alternatively be referred to as an electric motor speed request. However, one of ordinary skill in the art will understand that the desired drive request  332  may be any desired value, command, or input signal from the user, and the controller  310  may determine a value from the desired drive request  332 , such as a desired output speed, force, torque (or rotational force), or power. 
     The electric motor value  334  may indicate an actual speed of the electric motor  216 . The electric motor value  334  may be transmitted from a sensor (not shown) configured to measure rpm, a voltage difference, a current, etc. from the electric motor  216 . The sensor may be a voltage sensor implemented by a coil wrapped around a conductor carrying current to the electric motor  216 , but aspects disclosed herein are not limited. As an alternative to speed, the electric motor value  334  may be an actual output torque, power, etc. calculated from a sensed measurement of the electric motor  216 , or an applied torque, power, etc. used to drive the electric motor  216  and/or an amount of power supplied from the battery  212 . Alternatively or in addition to the electric motor value  334 , the controller  310  may store capability data of the electric motor  216 . The capability data may include rating, a known maximum speed, torque, power, etc. of the electric motor  216 , e.g., based on the size and type of the electric motor  216 . This capability data may be communicated from the electric motor  216  as an additional signal, may be communicated from the user interface  320 , or may be pre-stored in the controller  310 . 
     The electric motor output  338  may be a command or signal to the electric motor controller  214  to drive the electric motor  216 . The electric motor output  338  may be based on the desired speed request  332 . The electric motor output  338  may be, for example, a requested speed of the electric motor  216  and/or an on/off command for the electric motor  216 . 
     The hydraulic motor output  336  may be a command or signal to the hydraulic circuit  252  to drive the hydraulic motor  254 . The hydraulic motor output  336  may be, for example, a requested speed of the hydraulic motor  254 , or alternatively, an on/off command to the hydraulic circuit  252  and/or hydraulic motor  254 . The hydraulic motor output  336  may be a valve command indicating a desired flow of hydraulic fluid to the hydraulic motor  254  and/or indicating a desired opening degree of a valve in the hydraulic circuit  252 . The hydraulic motor output  336  may be a function of an amount of the desired speed request  332  that the electric motor  216  is unable to provide. For example, the hydraulic motor output  336  may be proportional to a difference between the actual motor speed  334  and the desired speed request  332 . Alternatively or in addition thereto, the hydraulic motor output  336  may be proportional to a difference between a maximum speed of the electric motor  216  stored in or determined by the controller  310  and the desired speed request  332 . 
     The controller  310  may be configured to compare the plurality of inputs  332 ,  334  to each other and/or with stored capability data to control the hydraulic motor  254  via the hydraulic circuit  252 . The controller  310  may determine whether the electric motor  216  is capable of fulfilling or is currently fulfilling the desired speed request  332 . For example, the controller  310  may determine that the actual motor speed  334  of the electric motor  216  is less than the desired speed request  332  of the conveyor drive system  200 , and determine a speed at which to drive the hydraulic motor  254  to fulfill the desired speed request  332 , which may be indicated by the hydraulic motor output  336 . As another example, the controller  310  may determine that the maximum motor speed stored in the controller  310  is unable to fulfill the desired speed request  332 , and determine the speed at which to drive the hydraulic motor  254 , which may be indicated by the hydraulic motor output  336 . 
     Systems and methods disclosed herein are not limited to a specific calculation occurring in the controller  310  and/or specific formats and values of the inputs  332 ,  334 , electric motor output  338 , and hydraulic motor output  336 . One of ordinary skill in the art will understand that the controller  310  may be configured to convert and/or calculate from the inputs  332 ,  334  values which are readily comparable, and determine the hydraulic motor output  336  appropriate for the hydraulic circuit  252  and/or the hydraulic motor  254 . For example, the hydraulic motor output  336  may indicate an amount or pressure of hydraulic fluid to be supplied to the hydraulic motor  254 , a degree of opening of a valve, etc. As another example, the hydraulic motor output  336  may indicate a command for the hydraulic motor  254  to engage with and/or disengage from the electric motor  216 , to speed up the hydraulic motor  254 , etc. As another example, the plurality of inputs  332 ,  334  may include multiple sensed values in relation to the electric motor  216  and/or output shaft  290 . For example, the controller  310  may receive a torque or power applied to the electric motor  216  and an actual rpm of the output shaft  290 , determine that the torque or power applied to the electric motor  216  is relatively high and/or that an actual rpm of the output shaft  290  is relatively low compared to an expected rpm at the applied torque or power, and provide an appropriate output  336  to the hydraulic circuit  252 . The controller  310  may also determine acceleration from the inputs  332 , and  334 . 
     As previously explained, the controller  310  may have a memory or electronic storage which stores the maximum speed or other capability or rating data of the electric motor  216 . The controller  310  may be configured to collect performance data of the electric motor  216 , store performance data in the memory, and determine a maximum speed of the electric motor  216  from this data, which may be used as (or used in a calculation to determine) input  334 . The controller  310  may also include software configured to perform operations shown in  FIG.  3   . The controller  310  may include a PCB, a processor, and other circuitry components to facilitate these operations. Numerous commercially available microprocessors can be configured to perform the functions of controller  310 . It should be appreciated that controller  310  could readily embody a general machine controller capable of controlling numerous other machine functions. Various other known circuits may be associated with controller  310 , including signal-conditioning circuitry, communication circuitry, hydraulic or other actuation circuitry, and other appropriate circuitry. Additionally, the controller  310  may be configured to send and receive information through wired means or wireless means. 
     The user interface  320  may be used to control the paver machine  10  and may include input and output keys, buttons, steering wheels, joysticks, displays, lights, a touch screen, etc. to input various commands and/or display various operations, such as relating to a movement of the paver machine  10  or a paving operation, and/or specific operations of the conveyor  110 , auger, hopper, screed  120 , etc. The user interface  320  may be configured to convert an input command from a user to the desired speed request  332  (e.g., in a form of a signal) in a particular format or value for the controller  310 . The user interface  320  may have a wired connection to the controller  310 , but systems and methods disclosed herein are not limited. For example, the user interface  320  and controller  310  may have communication modules capable of wireless communication (e.g., WiFi or Bluetooth modules, etc.) As another example, the user interface  320  may be a remote or mobile device (e.g., laptop or mobile phone) and/or receive input from a remote or mobile device. 
     INDUSTRIAL APPLICABILITY 
     The disclosed aspects of the mobile industrial machine of the present disclosure may be used to provide a hydraulic assistive force to a conveyor when an electric motor is unable to handle or efficiently handle high loads or torques. For example, an electric motor may not be able to efficiently start a conveyor  110 , even while operating at peak torques. As another example, the electric motor may not be able to drive the conveyor  110  at a desired speed due to an extra frictional force on the conveyor  110 , such as with large asphalt loading and/or sticking to the conveyor belt  112  and/or other surfaces of the paver machine. 
     Systems and methods disclosed herein may be less expensive by combining motor and drive systems which are smaller in size instead of using larger drive systems. For example, the conveyor drive system  200  may not require a very large electric motor system  210  because the conveyor drive system  200  also includes a hydraulic motor system  250 . Systems and methods disclosed herein may provide for a smaller paver machine  10  or other mobile industrial machine because a drive system  200  may be more compact and smaller. 
     Referring to  FIGS.  1 - 3   , aspects and methods disclosed herein may provide a method  3000  for operating the paver machine  10  to drive the conveyor  110 . The method  3000  may include, in step  3010 , receiving a desired request  332 . As noted above, the desired drive request  332  may be a desired motor speed request indicating a desired speed (e.g., rpm) of the electric motor  216 , conveyor drive system  200  and/or shaft  290 . The desired request  332  may alternatively indicate other desired outputs of the conveyor drive system  200 , such as an output torque or power used to drive the conveyor belt  112 . 
     The method  3000  may include, in step  3020 , driving the electric motor  216  based on the desired drive request  332 . Driving the electric motor  216  may include sending the electric motor command or signal  338  to the electric motor controller  214  indicating a certain speed for the electric motor  216 , a torque or power applied to the electric motor  216 , etc. The electric motor controller  214  may control and/or communicate with the electric motor  216  based on the electric motor command  338 . 
     The method  3000  may include, in step  3030 , sensing or determining an electric motor speed  334  of the electric motor  216 . The electric motor speed  334  may indicate an actual speed of the electric motor  216  sensed by a sensor (e.g., voltage sensor). 
     The method  3000  may include, in step  3040 , determining whether the electric motor  216  is able to provide a full amount of the desired drive request  332  based on the sensed electric motor speed  334 . The controller  310  may determine whether the electric motor  216  is able to fulfil the desired drive request  332  by comparing the desired drive request  332  with the sensed or determined electric motor speed  334 . As previously explained, methods and systems disclosed herein are not limited to specific calculations occurring in the controller  310 . 
     In step  3040 , determining whether the electric motor  216  is able to fulfil the desired drive request  332  may alternatively or additionally include comparing the desired drive request  332  with capability data (e.g., a maximum speed or rating). For example, the controller  310  may, before step  3030 , first determine whether the electric motor  216  is able to fulfil the desired drive request  332  by comparing the desired drive request  332  with a maximum speed of the electric motor  216  stored in the memory of the controller  310  or determined by the controller  310  based on other stored capability data. If the controller  310  determines that the rating and/or maximum speed of the electric motor  216  is unable to fulfil the desired drive request  332 , then the controller  310  does not need to receive the electric motor speed  332  in step  3030 . 
     If, in step  3040 , it is determined that the electric motor  216  is unable to provide the full amount of the desired request  332  (“No” after step  3040 ), then the method  3000  may include, in step  3050 , driving the hydraulic motor  254 . The hydraulic motor  254  may be driven to provide an assistive speed, torque, or power to drive the conveyor  110 . Driving the hydraulic motor  254  may include driving the hydraulic motor  254  at a predetermined speed, torque, power, etc. to provide a determined assistive torque to drive the conveyor  110  to meet the desired drive request  332 . The driving the hydraulic motor  254  may be a function of an amount of the desired drive request  332  that the electric motor  216  is unable to provide. Alternatively, driving the hydraulic motor  254  may include turning on and/or engaging the hydraulic motor  254  with the electric motor  216 . The hydraulic motor  254  may be configured to provide a majority of the desired speed request  332  during peak loads, such as in a range of up to 60-70% of the full amount, but aspects disclosed herein are not limited. 
     If, in step  3040 , it is determined that the electric motor  216  is able to provide the full amount of the desired drive request  332  (“Yes” after step  3040 ), then the hydraulic motor  254  may not be driven in step  3060 . 
     Some or all of the steps  3010 - 3060  of the method  3000  may be repeated. For example, the method  3000  may continuously receive a desired motor speed request  332  in step  3010 . If a user has not input a “stop” request or a different request from a previously input desired motor speed request  332 , then the controller  310  may continuously receive or consider the same desired motor speed request  332  at this step  3010 , drive the electric motor  216  based on the received desired motor speed request  332  in step  3010 , and repeat sensing the electric motor speed in step  3030 . Alternatively, after step  3050 , if no other desired drive requests  332  are input, the method  3000  may be repeated beginning with step  3030  of sensing the electric motor speed  334 . 
     If, after repeating step  3040 , it is determined that the electric motor  216  is unable to provide or maintain the full amount of the desired speed request  332  (“No” after step  3040 ), step  3050  of driving the hydraulic motor  254  may be repeated. Depending on a comparison of the desired motor speed request  332  and the electric motor speed  334  in step  3040 , driving the hydraulic motor  254  in step  3050  may include increasing or decreasing a torque assist of the hydraulic motor  254  based on the comparison. 
     If, after repeating step  3040 , it is determined that the electric motor  216  is able to provide the full amount of the desired request  332  (“Yes” after step  3040 ), then step  3060  of not driving the hydraulic motor  254  may include discontinuing any torque assist from the hydraulic motor  254 . The hydraulic motor  254  may be turned off, or a torque assist of the hydraulic motor  254  may be gradually decreased. Determining that the electric motor  216  is able to provide the full amount of the desired drive request  332  in step  3040  may include determining that the electric motor  216  is able to maintain a speed indicated by the initial desired drive request  332 , even though the electric motor  216  was unable to accelerate to or achieve the initial desired drive request  332 . 
     As an example, although the method  3000  is described as operating a paver machine  10  to drive a conveyor  110 , alternatively, the method  3000  may be used to drive any driven component of the paver machine  10 . For example, the conveyor drive system  200  may be an auger drive system  200  to drive the auger, a hopper drive system  200  to drive the hopper, or a screed drive system  200  to drive the screed  120 . As another example, the paver  10  may include a conveyor drive system  200  to drive the conveyor  110 , a separate auger drive system  200  to drive the auger, a separate screed drive system  200  to drive the screed  120 , etc., where each drive system  200  includes its own electric motor system  210  and hydraulic motor system  250 . As another example, a single drive system  200  may be used to drive multiple driven components (e.g., conveyor  110  and an auger) via a plurality of chains  218  and/or shafts  290 , etc. 
     Although the method  3000  is described as operating a paver machine  10 , the method  3000  may alternatively be used to operate other mobile industrial machines to drive a common load. For example, the method  3000  may be used to operate a compactor  10  to drive a compactor vibrator using a compactor vibrator drive system  200 . The method  3000  may be used to drive a separate ground drive system  200  in mobile industrial machines (e.g., tractors). 
     Aspects of the present disclosure may provide a drive system including both an electric motor and a hydraulic motor to assist the electric motor to drive a common load. A control system may control the drive system according to one or more inputs indicating a desired request (e.g., a speed or output torque of the drive system) and one or more inputs indicating current or actual data of the common load (e.g., an actual speed of the drive system or of the electric motor). Aspects of the present disclosure may drive the common load primarily using an electric motor, and may control a hydraulic motor to provide an assistive torque when the electric motor is incapable of handling the common load or where driving only the electric motor would otherwise be inefficient. The hydraulic motor may provide an additive force, torque, power, or speed to that of the electric motor to increase a total torque, power, and/or speed provided by the drive system. 
     Aspects of the present disclosure may provide a way to handle infrequent maximum torque needs for an industrial mobile machine (e.g., paver machine). Aspects of the present disclosure may provide a drive system capable of handling sporadic peak requirements without requiring a larger or more expensive electric drive system or electric motor. For example, in a conveyor drive system configured to drive a conveyor, the conveyor may be typically pull about 1500 pounds per square inch (psi), but may have a maximum operating pressure of about 4000 psi. The drive system may include an electric drive system configured to drive the conveyor at typical pressures like 1500 psi or about ⅓ of the maximum power required, while the hydraulic drive system may be configured to assist driving the conveyor at maximum operating pressures. The electric drive system may provide the necessary power most of the time (e.g., 95% of the time), while the hydraulic drive system may assist during more infrequent instances where power power is required to drive the conveyor. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed method and system without departing from the scope of the disclosure. Other embodiments of the method and system will be apparent to those skilled in the art from consideration of the specification and practice of the systems disclosed herein. For example, why a hydraulic motor  254  and associated hydraulic circuit  252  is described above, it is understood that alternative additional drive systems may be provided, such as a different fluid drive such as a pneumatic drive system and associated motor. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalents.