Patent Publication Number: US-10323389-B2

Title: Control system and method for a machine

Description:
TECHNICAL FIELD 
     The present disclosure relates to a control system for a machine. More particularly, the present disclosure relates to a control system and method for regulating a machine&#39;s speed according to the position of an upper frame relative to a lower frame of the machine. 
     BACKGROUND 
     Work machines such as wheeled excavators include a lower frame and an upper frame that is rotatably mounted to the lower frame. The upper frame is capable of rotational movement relative to the lower frame while the lower frame is steerable in relation to a ground surface using wheels manipulated by a steering mechanism of the machine. A work implement is typically mounted to the upper frame via an arm assembly. Arm assemblies are usually articulated with respect to the upper frame for positioning the work implement. Typically, in such machines the upper frame is configured to rotate 360 degrees with respect to the lower frame. A cabin or seat for an operator is provided on the upper frame so the operator maintains visibility of the work implement as the upper frame rotates. 
     Some work machines, particularly wheeled machines, are capable of speeds in excess of 30 kph. The combination of speed and rotatability of the upper frame may give rise to difficulties in operator control of the machine. In particular, for example, when the upper frame is rotated such that an operator may be facing towards the rear of the lower frame, the operator controls may have a different resulting effect compared with the same controls used when the upper frame is aligned in the same facing direction as the lower frame. This may be counter intuitive for an operator and cause confusion in the controls, hence requiring an additional burden on the operator awareness and skill for operating the machine. 
     SUMMARY OF THE DISCLOSURE 
     In an aspect of the present disclosure, a control system for a work machine having an upper frame rotatably mounted to a lower frame includes a controller configured to limit a maximum speed of the machine when a rotation angle between the upper frame and the lower frame exceeds a first predetermined value. 
     In another aspect of the present disclosure, a work machine is provided. The work machine includes an upper frame rotatably mounted to a lower frame. The work machine further includes a controller operable to limit a maximum speed of the machine when a rotation angle between the upper frame and the lower frame exceeds a first predetermined value. 
     In yet another aspect of the present disclosure, a method for controlling a work machine is provided. The work machine has an upper frame rotatably mounted to a lower frame. The method includes limiting a maximum speed of the machine when a rotation angle between the upper frame and the lower frame exceeds a first predetermined value. Embodiments disclosed herein are also directed to a non-transient computer readable medium containing program instructions for causing a computer to perform the method of the present disclosure. 
     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 an exemplary work machine, according to an embodiment of the present disclosure; 
         FIG. 2  is a block diagram of a control system that can be implemented for controlling a movement of the work machine, according to an embodiment of the present disclosure; 
         FIG. 3  is a top perspective view of the exemplary work machine of  FIG. 1 , according to an embodiment of the present disclosure; 
         FIG. 4  is a first graph depicting changes to an exemplary maximum speed of the work machine, in accordance with an embodiment of this disclosure; 
         FIG. 5  is a second graph depicting changes to an exemplary maximum speed of the work machine, in accordance with another embodiment of this disclosure; 
         FIG. 6  is a third graph depicting changes to an exemplary maximum speed of the work machine, in accordance with yet another embodiment of this disclosure; 
         FIG. 7  is a fourth graph depicting changes to an exemplary maximum speed of the work machine, in accordance with an alternative embodiment of this disclosure; 
         FIG. 8  is a low-level implementation of the control system, in accordance with an embodiment of the present disclosure; and 
         FIG. 9  is a flowchart depicting a method for controlling operation of the exemplary machine of  FIG. 1 , according to 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.  FIG. 1  illustrates an exemplary work machine  100  (herein after referred to as “machine  100 ”). The machine  100  may be moved over a ground surface using wheels  102  provided on a lower frame  106  of the machine  100 . The machine  100  also includes an upper frame  104  on which an operator cab  108  and an engine (not shown) are supported. The upper frame  104  is coupled to the lower frame  106  via a swivel base  110  so that the upper frame  104  may be rotated, in use, with respect to the lower frame  106  about an axis AA′. 
     The machine  100  shown in  FIG. 1  is an excavator. Alternatively, the machine  100  may include other swivel machines, whether tracked or wheeled, in which an upper frame of the machine is capable of rotational motion with respect to a lower frame of the machine. 
     The machine  100  also includes an arm assembly  112  provided on the upper frame  104 . The arm assembly  112  includes a boom  114 , a stick  116  and an implement  118 . As shown, the boom  114  is pivotally connected at one end to the upper frame  104  of the machine  100  and is pivotally connected at another end thereof to the stick  116 . The implement  118  is connected to the stick  116  via a coupling mechanism  122 . The arm assembly  112  is actuated by a pair of hydraulic cylinders  120 . The arrangement of the arm assembly  112  described herein is exemplary in nature and does not limit the scope of the present disclosure. 
     Referring to  FIG. 1 , the implement  118  is work tool in the form of a bucket. Other forms of implement  118  may also be used according to the task to be performed. For example, the implement  118  may be a grappler, a hammer, a fork, a lifting hook, a saw, a rotary broom, a shear, or any other appropriate work tool known in the art. 
     The operator cab  108  includes a number of input devices (not shown) including, but not limited to, a control panel, joysticks, and levers for the operator to control one or more operations of the machine  100  and the implement  118 . During operation, the engine may drive a hydraulic pump (not shown) to supply high pressure hydraulic fluid to a hydraulic system. The hydraulic system may be used to actuate the hydraulic cylinders  120  provided in association with the boom  114 , the stick  116 , and the implement  118 . 
     The present disclosure relates to a control system  200  (shown in  FIG. 2 ) associated with the machine  100 . Referring to  FIG. 2 , the control system  200  includes a sensor  202  that is associated with the upper and lower frames  104 ,  106  of the machine  100 . The sensor  202  is configured to detect a rotation angle α between the upper frame  104  and the lower frame  106  of the machine  100 , and generate a signal indicative of the rotation angle α of the upper frame  104  relative to the lower frame  106 . 
     The control system  200  also includes a controller  204  communicably coupled to the sensor  202 . The controller  204  is configured to generate appropriate signals to control a speed of travel for the machine  100  based the signal from the sensor  202  as will be described in more detail below. 
     The controller  204  is communicably coupled to a swing control device  206  e.g., a joystick that could be conveniently located within the operator cab  108  for use by an operator of the machine  100 . The controller  204  is configured to receive user commands from the swing control device  206  for swiveling the upper frame  104  relative to the lower frame  106 . A direction of swivel motion associated with the upper frame  104  i.e., in a clockwise or counter-clockwise direction about the axis AA′ and a speed of swivel movement to be executed by the upper frame  104  may be defined by the type of user input provided at the swing control device  206 . 
     The controller  204  is also in communication with a memory  210 . The memory  210  may include any known data storage and retrieval device. The controller  204  may be an electronic controller that operates in a logical fashion to perform operations, execute control algorithms, store and retrieve data and other desired operations. The controller  204  may include or access memory, secondary storage devices, processors, and any other components for running an application. The memory and secondary storage devices may be in the form of read-only memory (ROM) or random access memory (RAM) or integrated circuitry that is accessible by the controller  204 . Various other circuits may be associated with the controller  204  such as power supply circuitry, signal conditioning circuitry, driver circuitry, and other types of circuitry. 
     The controller  204  may be a single controller or may include more than one controller disposed to control various functions and/or features of the machine  100 . The term “controller” is meant to be used in its broadest sense to include one or more programmable logic controllers, embedded controllers, microcontrollers and/or microprocessors that may be associated with the machine  100  and that may cooperate in controlling various functions and operations of the machine  100  disclosed herein. 
     The memory  210  may be configured to store a first predetermined value V1 associated with the rotation angle α of the upper frame  104  relative to the lower frame  106 . In embodiments of this disclosure, the controller  204  is configured to generate appropriate signals to limit a maximum speed, S max , of the machine  100  when an angular position of the upper frame  104  and the lower frame  106  as detected by the sensor  202  exceeds the first predetermined value V1. The controller  204  may compare the detected rotation angle α received from the sensor  202  with the first predetermined value V1. If the detected rotation angle α exceeds the first predetermined value V1, the controller  204  generates appropriate signals to limit the maximum speed S max  of the machine  100 . In embodiments of this disclosure, the controller may generate appropriate signals to limit the maximum speed S max  of the machine to less than 10 kilometers per hour (km/h). However, it may be noted that 10 km/h disclosed herein is non-limiting of this disclosure, the maximum speed S max  of the machine  100  may be limited to any suitable value depending on specific requirements of an application. For example, the maximum speed S max  of the machine  100  may be limited to 15 km/h in lieu of the 10 km/h limit disclosed herein. 
     The sensor  202  may measure the rotation angle α of the upper frame  104  with reference to a datum associated with the lower frame  106 . By way of example, it can be contemplated that the datum may be disposed in line with a longitudinal plane BB′ of the fixed lower frame  106  of the machine  100  as shown in  FIG. 3 . More particularly, the sensor  202  may measure a difference in position of a reference plane of the upper frame  104 , for example, a longitudinal plane CC′ of the upper frame  104  with the datum e.g., the longitudinal plane BB′ of the lower frame  106 . 
     In an example configuration shown in  FIG. 4 , the first predetermined value V1 may be set to 85 degrees, the first predetermined value V1 also being taken in reference to the datum i.e., the longitudinal plane BB′ of the lower frame  106 . Upon receiving the rotation angle α of the upper frame  104  from the sensor  202 , the controller  204  may compare the detected rotation angle α with the first predetermined value V1 e.g., 85 degrees as shown in  FIG. 4 . If the detected rotation angle α exceeds the first predetermined value V1 of 85 degrees, the controller  204  generates appropriate signals to limit the maximum speed S max  of the machine  100 , for example, from 35 kilometers per hour (km/h) to 8 km/h as shown in the graph  400  of  FIG. 4 . The terms “maximum speed” disclosed herein could be regarded as the maximum wheel speed of the machine  100 , or could alternatively be taken as the maximum ground speed of the machine  100  assuming that there would be no loss of traction at the wheels  102 . Numerous methods are well known in the art for also correlating an engine speed at a given transmission ratio to obtain a given maximum wheel speed or maximum ground speed of the machine  100 . Such methods may be implemented for facilitating the controller  204  in generating signals to control the engine speed such that a desired maximum speed S max  of the machine  100  i.e., desired maximum wheel speed or desired maximum ground speed of the machine  100  can be achieved. 
     In an additional embodiment, the memory  210  associated with the controller  204  may be provided with a second predetermined value V2, the second predetermined value V2 also being taken in reference to the datum e.g., with respect to the longitudinal plane BB′ of the lower frame  106 . Upon receiving the rotation angle α of the upper frame  104  from the sensor  202 , the controller  204  may determine if the detected rotation angle α lies between the second predetermined value V2 e.g., 85 degrees and the first predetermined value V1 e.g., 95 degrees as shown in  FIG. 5 . If so, the controller  204  is configured to generate appropriate signals to gradually reduce the maximum speed S max  of the machine  100  according the rotation angle α. In  FIG. 5 , this is shown as a gradual reduction in maximum speed from 35 km/h to 8 km/h as indicated by a slope dV/dS max . 
     In embodiments of this disclosure, the first and second predetermined values V1, V2 may beneficially lie within a range of 70-110 degrees with respect to the datum e.g., the longitudinal plane BB′ of the lower frame  106  shown in the illustrated embodiment of  FIG. 3 . For example, as shown in  FIG. 5 , the second predetermined value V2 for the longitudinal plane CC′ of the upper frame  104  with respect to the longitudinal plane BB′ of the lower frame  106  is set at 85 degrees while the first predetermined value V1 for the longitudinal plane CC′ of the upper frame  104  with respect to the longitudinal plane BB′ of the lower frame  106  is set at 95 degrees. 
     In another example configuration as shown by way of a graph  600  in  FIG. 6 , the second predetermined value V2 for the longitudinal plane CC′ of the upper frame  104  with respect to the longitudinal plane BB′ of the lower frame  106  is set at 75 degrees while the first predetermined value V1 for the longitudinal plane CC′ of the upper frame  104  with respect to the longitudinal plane BB′ of the lower frame  106  is set at 85 degrees. 
     In yet another example as shown by way of a graph  700  in  FIG. 7 , the second predetermined value V2 for the longitudinal plane CC′ of the upper frame  104  with respect to the longitudinal plane BB′ of the lower frame  106  is set at 90 degrees while the first predetermined value V1 for the longitudinal plane CC′ of the upper frame  104  with respect to the longitudinal plane BB′ of the lower frame  106  is set at 100 degrees. 
     It is to be noted that the positive and negative values of the rotation angle α and each of the first and second predetermined values V1, V2 indicated in  FIGS. 4 to 7  are indicative of a clockwise rotation and a counter-clockwise rotation of the upper frame  104  about the axis AA′ (shown in  FIG. 1 ) e.g., in reference to the longitudinal plane BB′ of the lower frame  106  as shown in  FIG. 3  in which movement of the upper frame  104  and its longitudinal plane CC′ leftward of the longitudinal plane BB′ associated with the lower frame  106  may be considered to represent a counter-clockwise rotation of the upper frame  104  while movement of the upper frame  104  and its longitudinal plane CC′ rightward of the longitudinal plane BB′ associated with the lower frame  106  may represent a clockwise rotation of the upper frame  104 . 
     Although it is disclosed herein that the first and second predetermined values V1, V2 may lie between 70-110 degrees as shown in  FIGS. 3-7 , the first and second predetermined values V1, V2 are non-limiting of this disclosure. It will be appreciated that the first and second predetermined values V1, V2 can be varied to advantageously suit specific requirements of an application including, but not limited to, a type of machine used, one or more operating conditions typically associated with the machine, and the like. 
     In an example, the second predetermined value V2 may be set at 55 degrees while the first predetermined value V1 may be set at 65 degrees so that when the longitudinal plane CC′ of the upper frame  104  exceeds the second predetermined value V2 of 55 degrees with respect to the longitudinal plane BB′ of the lower frame  106 , the controller  204  commands a gradual reduction in the maximum speed S max  of the machine  100  from 35 km/h to 8 km/h until the longitudinal plane CC′ of the upper frame  104  reaches the first predetermined value V1 of 65 degrees with respect to the longitudinal plane BB′ of the lower frame  106  after which the controller  204  generates signals to limit the maximum speed S max  of the machine  100  to 8 km/h. 
     It may be noted that the controller  204  can be suitably coupled to numerous components of the machine  100  such as, but not limited to, the engine, a brake system, or a governor (if present) on the machine  100  for modulating an operation of such components so that the maximum speed S max  of the machine  100  can be advantageously reduced or limited in accordance with embodiments disclosed herein while the upper frame  104  is being rotated about the lower frame  106  in reference to the second and first predetermined value V1s respectively. 
     Further, it is contemplated that the rotation angle α of the upper frame  104  relative to the lower frame  106  as detected by the sensor  202  may also be provided by the controller  204  to the memory  210  so that when the machine  100  is switched “OFF” and turned back “ON” to an operative state, the controller  204  can access the last known rotation angle α of the upper frame  104  relative to the lower frame  106  that is stored at the memory  210  and control the maximum speed S max  of the machine  100  based on such stored rotation angle α. It is also contemplated that the controller  204  could beneficially update the memory  210  with the latest detected rotation angle α each time the angular position of the upper frame  104  relative to the lower frame  106  changes, or alternatively at pre-determined intervals of time, suitable values of which would be apparent based on the angular velocity of the upper frame  104 . 
     Moreover, as shown in  FIG. 2 , the control system  200  may also include a speed limit indicator  212  communicably coupled to the controller  204 . Based on the current angular position of the upper frame  104  updated by the controller  204  at the memory  210 , the controller  204  may also generate signals that control the speed limit indicator  212  to indicate whether the speed S max  of the machine is being limited by the controller  204 . The speed limit indicator  212  may be embodied in the form of any known indication device including, but not limited to, a light device such as an LED, a graphical user interface (GUI), or a sound emitting device such as a loudspeaker or piezoelectric device configured to indicate to an operator whether the speed limitation is in effect. 
       FIG. 8  is an exemplary low-level implementation of the control system  200  from  FIG. 2  for controlling operation of the exemplary machine  100  of  FIG. 1  in accordance with embodiments of the present disclosure. For the sake of simplicity in this document, the low-level implementation of the control system  200  will hereinafter be referred to as ‘a computer system’ and designated with similar reference numerals to those win  FIG. 2  increased by 600 i.e., reference numeral ‘800’). 
     The present disclosure has been described herein in terms of functional block components, modules, and various processing steps. It should be appreciated that such functional blocks may be realized by any number of hardware and/or software components configured to perform the specified functions. For example, the controller  204  of the control system  200  may employ various integrated circuit components, e.g., memory elements, processing elements, logic elements and the like which may carry out a variety of functions under the control of one or more microprocessors or other control devices. Similarly, the software elements of the system  800  may be implemented with any programming or scripting language such as C, C++, Java, COBOL, assembler, PERL, Visual Basic, SQL Stored Procedures, extensible markup language (XML), with the various algorithms being implemented with any combination of data structures, objects, processes, routines or other programming elements. Further, it should be noted that the system  800  may employ any number of conventional techniques for data transmission, signaling, data processing, network control, and/or the like. Still further, the system  800  could be configured to detect or prevent security issues with a user-side scripting language, such as JavaScript, VBScript or the like. In an embodiment of the present disclosure, the networking architecture between components of the system  800  may be implemented by way of a client-server architecture. In an additional embodiment of this disclosure, the client-server architecture may be built on a customizable .Net (dot-Net) platform. However, it may be apparent to a person ordinarily skilled in the art that various other software frameworks may be utilized to build the client-server architecture between components of the control system  200  without departing from the spirit and scope of the disclosure. 
     These software elements may be loaded onto a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions that execute on the computer or other programmable data processing apparatus create means for implementing the functions specified in the flowchart block or blocks. These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce instructions which implement the function specified in the flowchart block or blocks. The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. 
     The present disclosure (i.e., control system  200 , method  900 , any part(s) or function(s) thereof) may be implemented using hardware, software or a combination thereof, and may be implemented in one or more computer systems or other processing systems. However, the manipulations performed by the present disclosure were often referred to in terms such as detecting, determining, and the like, which are commonly associated with mental operations performed by a human operator. No such capability of a human operator is necessary, or desirable in most cases, in any of the operations described herein, which form a part of the present disclosure. Rather, the operations are machine operations. Useful machines for performing the operations in the present disclosure may include general-purpose digital computers or similar devices. As such, the functions of the controller  204  can also be applied for execution in the machine  100  regardless of the machine&#39;s level of automation, such levels of automation including, but not limited to, an operator assisted mode, a remotely operated mode, a supervised mode, or a fully autonomous mode. 
     In accordance with an embodiment of the present disclosure, the present disclosure is directed towards one or more computer systems capable of carrying out the functionality described herein. An example of the computer based system includes the computer system  800 , which is shown by way of a block diagram in  FIG. 8 . 
     The computer system  800  includes at least one processor, such as a processor  802 . The processor  802  may be connected to a communication infrastructure  804 , for example, a communications bus, a cross-over bar, a network, and the like. Various software embodiments are described in terms of this exemplary computer system  800 . Upon perusal of the present description, it will become apparent to a person skilled in the relevant art(s) how to implement the present disclosure using other computer systems and/or architectures. 
     The computer system  800  includes a display interface  806  that forwards graphics, text, and other data from the communication infrastructure  804  for display on a display unit  808 . In an embodiment, the display interface  806  and/or the display unit  808  could be beneficially embodied in the form of a Graphical User Interface (GUI) or other equivalent devices capable of receiving user commands. Such display interface and/or unit  806 ,  808  could also be located at a remote operator station (not shown) for displaying to a remotely located operator the type of control being currently implemented on the maximum speed S max  of the machine  100  and hence, also on the travel speed of the machine  100  based on the detected rotation angle α of the upper frame  104  relative to the lower frame  106 . 
     The computer system  800  further includes a main memory  810 , such as random access memory (RAM), and may also include a secondary memory  812 . The secondary memory  812  may further include, for example, a hard disk drive  814  and/or a removable storage drive  816 , representing a floppy disk drive, a magnetic tape drive, an optical disk drive, etc. The removable storage drive  816  reads from and/or writes to a removable storage unit  818  in a well-known manner. The removable storage unit  818  may represent a floppy disk, magnetic tape or an optical disk, and may be read by and written to by the removable storage drive  816 . As will be appreciated, the removable storage unit  818  includes a computer usable storage medium having stored therein, computer software and/or data. 
     In accordance with various embodiments of the present disclosure, the secondary memory  812  may include other similar devices for allowing computer programs or other instructions to be loaded into the computer system  800 . Such devices may include, for example, a removable storage unit  820 , and an interface  822 . Examples of such may include a program cartridge and cartridge interface (such as that found in video game devices), a removable memory chip (such as an erasable programmable read only memory (EPROM), or programmable read only memory (PROM)) and associated socket, and other removable storage units  820  and interfaces  822 , which allow software and data to be transferred from the removable storage unit  820  to the computer system  800 . 
     The computer system  800  may further include a communication interface  824 . The communication interface  824  allows software and data to be transferred between the computer system  800  and the external devices  880 . Examples of the communication interface  824  include, but may not be limited to a modem, a network interface (such as an Ethernet card), a communications port, a Personal Computer Memory Card International Association (PCMCIA) slot and card, and the like. Software and data transferred via the communication interface  824  may be in the form of a plurality of signals, hereinafter referred to as signals  826 , which may be electronic, electromagnetic, optical or other signals capable of being received by the communication interface  824 . The signals  826  may be provided to the communication interface  824  via a communication path (e.g., channel)  828 . The communication path  828  carries the signals  826  and may be implemented using wire or cable, fiber optics, a telephone line, a cellular link, a radio frequency (RF) link and other communication channels. 
     In this document, the terms “computer program medium” and “computer usable medium” are used to generally refer to media such as the removable storage drive  816 , a hard disk installed in the hard disk drive  814 , the signals  826 , and the like. These computer program products provide software to the computer system  800 . The present disclosure is also directed to such computer program products. 
     Computer programs (also referred to as computer control logic) may be stored in the main memory  810  and/or the secondary memory  812 . Computer programs may also be received via the communication interface  804 . Such computer programs, when executed, enable the computer system  800  to perform the functions consistent with the present disclosure, as discussed herein. In particular, the computer programs, when executed, enable the processor  802  to perform the features of the present disclosure. Accordingly, such computer programs may represent controllers of the computer system  800 . 
     In accordance with an embodiment of the present disclosure, where the disclosure is implemented using a software, the software may be stored in a computer program product and loaded into the computer system  800  using the removable storage drive  816 , the hard disk drive  814  or the communication interface  824 . The control logic (software), when executed by the processor  802 , causes the processor  802  to perform the functions of the present disclosure as described herein. 
     In another embodiment, the present disclosure is implemented primarily in hardware using, for example, hardware components such as application specific integrated circuits (ASIC). Implementation of the hardware state machine so as to perform the functions described herein will be apparent to persons skilled in the relevant art(s). 
     In yet another embodiment, the present disclosure is implemented using a combination of both the hardware and the software. 
       FIG. 9  illustrates a method  900  of operation of the control system  200 . At step  902 , a rotational movement of the upper frame  104  about the lower frame  106  is initiated i.e., movement of the upper frame  104  is initiated about the swivel axis AA′. At step  904 , the sensor  202  detects the angular position of the upper frame  104  relative to the lower frame  106 . If the rotation angle α of the upper frame  104  relative to the lower frame  106  detected by the sensor  202  is less than the second predetermined value V2, then the controller  204 , at step  906 , allows operation of the machine  100  to be carried out at any speed up to its rated maximum allowable speed e.g., at the maximum speed S max  of 35 km/h as shown in  FIGS. 4-7 . 
     If the rotation angle α detected by the sensor  202  lies between the second predetermined value V2 and the first predetermined value V1, then at step  908 , the controller  204  generate signals to gradually reduce the maximum speed S max  of the machine  100 . A rate of deceleration or retardation of the machine  100  could be selected depending on specific requirements of an application, for example, based on a type of machine used, a rapidity with which operations in the machine may be carried out and the like. 
     If the rotation angle α of the upper frame  104  relative to the lower frame  106  detected by the sensor  202  exceeds the first predetermined value V1, then the controller  204 , at step  910 , generate signals to limit the maximum speed S max  of the machine  100 , for example, from 35 km/h to 8 km/h as shown by way of example in each of the  FIGS. 4-7 . 
     The present disclosure provides the system  200  and the method  900  by which the maximum speed S max  and hence, the travel speed of the machine  100  may be controlled based on a movement of the upper frame  104  relative to the lower frame  106  of the machine  100 . By gradually reducing travel speed of the machine  100  before limiting the maximum speed S max  of the machine  100 , changes in the speed of movement associated with the machine  100  may be made smoothly. It is envisioned that reducing or limiting the maximum speed S max  of the machine  100  while the upper frame  104  is rotated about the lower frame  106  also aids the operator in providing better control over the movement of the machine  100 . 
     Various embodiments disclosed herein are to be taken in the illustrative and explanatory sense, and should in no way be construed as limiting of the present disclosure. All numerical terms, such as, but not limited to, “first”, “second”, “third”, or any other ordinary and/or numerical terms, should also be taken only as identifiers, to assist the reader&#39;s understanding of the various embodiments, variations, components, and/or modifications of the present disclosure, and may not create any limitations, particularly as to the order, or preference, of any embodiment, variation, component and/or modification relative to, or over, another embodiment, variation, component and/or modification. 
     It is to be understood that individual features shown or described for one embodiment may be combined with individual features shown or described for another embodiment. The above described implementation does not in any way limit the scope of the present disclosure. Therefore, it is to be understood although some features are shown or described to illustrate the use of the present disclosure in the context of functional segments, such features may be omitted from the scope of the present disclosure without departing from the spirit of the present disclosure as defined in the appended claims. 
     INDUSTRIAL APPLICABILITY 
     The present disclosure is applicable for use in work machines, such as wheeled excavators, in which an upper frame is rotatably mounted to a lower frame. The control system and method of the present disclosure may improve operator control of the machine when the machine is operated with the upper frame is rotated relative to the lower frame. 
     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 the disclosure. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.