Abstract:
In the operation of work machines it has been a problem to control the work machine&#39;s velocity aspects such as velocity, acceleration, deceleration and jerk because of the plurality of operator interfaces required for such control. The present invention provides an operator interface system for a work machine in which a first pedal is displaceable from a neutral position, and a sensor is operatively coupled with the first pedal and is operable to output a displacement signal corresponding to a location of the first pedal. An electronic controller receives the displacement signal and provides a predetermined control to a velocity aspect of the work machine in response to the displacement signal.

Description:
[0001]     This application is a continuation of U.S. patent application Ser. No. 09/973,266 filed Oct. 9, 2001 (now abandoned). This application also claims the benefit of U.S. provisional application No. 60/258,177 filed Dec. 22, 2000. 
     
    
     FIELD OF THE INVENTION  
       [0002]     This invention relates to an operator interface system for a work machine and, more particularly, to an operator interface system which uses foot operated pedals to control different velocity aspects of the work machine  
       BACKGROUND  
       [0003]     In the operation of modem day construction machines, control of various velocity aspects of the work machine such as acceleration, deceleration, machine speed, and sudden changes in acceleration or deceleration, or jerk, are oftentimes controlled through a plurality of operator interface devices. For example, driving a conventional wheel loader requires the operator to administer to an assortment of input devices such as the throttle pedal, impeller clutch/brake pedal, brake pedals, toggle and other types of switches, steering wheel or joystick, implement levers or joystick, and other interface controls. The necessity for the work machine operator to manipulate the aforementioned interface controls may not only make it difficult for a new operator to become efficient quickly in operating a particular machine, but also may result in erratic operation of the work machine if the operator fails to properly orchestrate the numerous interface controls.  
         [0004]     One prior art example of a pedal control system for a work vehicle can be found in U.S. Pat. No. 5,231,891 issued on Aug. 3, 1993 to Shigeru Morita et al. In this design, a dual pedal arrangement is used to provide a change speed function in which one pedal is coupled to the transmission via mechanical linkages and the other pedal is coupled to the first pedal. While this design may be adequate for its intended purpose, it fails to teach the use of a means to provide pre-determined control of the machines velocity, acceleration, deceleration and jerk. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]      FIG. 1  is a diagrammatic top view of an operator&#39;s station that embodies the principles of an embodiment of the operator interface system of the present invention.  
         [0006]      FIG. 2  is a block diagram of the operator interface system of  FIG. 1 .  
         [0007]      FIGS. 3A and 3B  are graphical illustrations of an embodiment of, respectively, acceleration and deceleration responses in accordance with the teachings of the present invention.  
         [0008]      FIG. 4  is a diagrammatic top view of an operator&#39;s station that embodies the principles of another embodiment of the operator interface system of the present invention.  
         [0009]      FIG. 5  is a diagrammatic top view of an operator&#39;s station that embodies the principles of yet another embodiment of the operator interface system of the present invention.  
         [0010]      FIG. 6  is a diagrammatic illustration of the operator interface system of  FIG. 2  shown being used with a continuously variable transmission.  
     
    
     DETAILED DESCRIPTION  
       [0011]     Referring to  FIG. 1 , a diagram of an operator station for a vehicle, denoted generally at  100 , embodying an embodiment of an operator interface system is shown. As should be appreciated, all embodiments of the operator interface system described herein allow the operator to control a variety of velocity aspects of a work machine (not shown) such as velocity, acceleration, deceleration, and jerk through use of a foot operated pedals. The operator station  100  may include a steering wheel  101 , a throttle control setting  102 , a maximum speed setting  105 , a parking brake  106 , and a forward/reverse cane  107  which may be coupled to the steering wheel column (not shown).  
         [0012]     The operator interface system includes a first pedal  110 , preferably operable by one foot of the operator, and a second pedal  111  which is preferably operated by the other foot of the operator. Each of the aforementioned first and second pedals  110 , 111  are actuatable from a base or neutral position by operation of pressure applied by the operator&#39;s foot, and each are coupled to the work machine body by conventional methods. Once the aforementioned pressure is released, the previously depressed pedal returns to its neutral position by conventional means such as either electrical and/or mechanical and/or pneumatic and/or hydraulic, or any combination thereof. In addition, a brake  112  may be provided to stop the work machine in a conventional manner. Alternatively, the second pedal  111  may be operatively coupled to the brake  112  in a conventional manner such as, for example, a mechanical or hydromechanical interconnection (not shown). When arranged in this manner, the brake  112  is preferably activated towards the end of the travel of the second pedal  111 , from its neutral position, with activation preferably occurring at about, for example, the remaining six (6) degrees of travel of the second pedal  111 .  
         [0013]     With reference to  FIG. 2 , the present operator interface system also includes a first position sensor and a second position sensor, both designated herein as  200 , operatively connected with each respective pedal  110 , 111 . Each sensor  200  operates in a conventional manner to sense displacement of each pedal  110 , 111  from each pedals respective neutral position, and to generate displacement signals based on the pedals respective positions. Each of the sensors  200  are coupled to an electronic control module (ECM)  201  and input the aforementioned displacement signals to the ECM  201  indicative of the respective displacement of the each pedal  110 , 111 . The ECM  201  is programmed to output signals to the corresponding work machine&#39;s systems in order to control the work machine&#39;s velocity aspects such as speed, acceleration, deceleration and jerk based upon the sensed operator input settings as determined by the displacement of the pedals  110 , 111  from the respective neutral position.  
         [0014]     Electronic controllers or modules such as the ECM  201  are commonly used in association with work machine-type vehicles for accomplishing a wide variety of tasks. In this regard, the ECM  201  will typically include processing means such as a microcontroller or microprocessor, associated electronic circuitry, analog circuit or programmed logic arrays, and associated memory. Thus, the ECM  201  can be programmed to control the various work machines components, to effectuate desired velocity aspects of the work machine, based on the displacement of the pedals  110 , 111 . Programming of the ECM  201  to accomplish the aforementioned functions is preferably accomplished by mapping structures which allow the ECM  201  to sense which of the pedals  110 , 111  is being moved relative to its respective neutral position. Based upon the target velocity desired by the operator, as defined by the instantaneous position of a respective pedal  110 , 111 , the mapping structures will appropriately direct the ECM  201  to accelerate or decelerate the work machine at pre-determined rates. Likewise, changes in acceleration and deceleration, or jerk, can also be controlled so as to provide for smoother operation of the work machine.  
         [0015]     Shown in  FIGS. 3A and 3B  are, respectively, one embodiment each of exemplary acceleration and deceleration graphs corresponding to a preferred mapping structure which can be used for any of the operator interface system embodiments described herein. However, for exemplary purposes, the  FIG. 1  operator interface system embodiment will be used to describe the exemplary embodiments of the aforementioned acceleration and deceleration graphs. As shown in  FIG. 3A , line  301  denotes displacing and holding at full displacement from the neutral position the first pedal  110  which results in a pre-selected maximum acceleration followed by cruising at the desired top speed velocity. Line  302  denotes full displacement and release of the first pedal  110  which results in the pre-selected maximum acceleration followed by limited pre-determined deceleration. Finally, line  303  denotes a displacement of the first pedal  110  between the neutral and full displacement positions which allows for a pre-determined intermediate acceleration followed by a pre-determined limited deceleration upon release of the first pedal  110 .  
         [0016]     As should be appreciated, the first pedal  110  may further be configured to provide the work machine with cruise control capability as represented by lines  304  and  305  in  FIG. 3A  (both shown in alternate detail). The cruise control function may be initiated in a conventional manner such as by actuating a toggle (not shown) or other suitable interface control. Upon such actuation, the ECM  201  is programmed to remember the position of the first pedal  110  and maintain a constant velocity associated with this position. Tapping on brake  112  releases the first pedal  110  causing the work machine to decelerate.  
         [0017]     Turning now to  FIG. 3B , and as denoted by line  306 , fully displacing and holding the second pedal  111  provides for the programmed maximum deceleration rate which, if the second pedal  111  remains fully depressed, will stop the work machine. Line  307  denotes a full displacement of the second pedal  111  followed by a partial release of the second pedal  111  which results in maximum deceleration followed by intermediate speed. Finally, line  308  denotes a partial displacement of the second pedal  111  which provides for limited deceleration followed by an intermediate speed.  
         [0018]     Alternatively, each of the aforementioned pedals  110 , 111  may be used to control directional movement of the work machine. Specifically, each of the pedals  110 , 111  may be coupled in a conventional manner to the transmission or other systems associated with work machine such that displacement of the first pedal  110  causes forward movement of the work machine. Likewise, displacement of the second pedal  111  causes the work machine to move in the reverse, or backing-up, direction. The ECM  201  can therefore be programmed to sense which pedal  110 , 111  is being depressed and output the appropriate signal to the work machine components to effectuate the desired movement in a controlled manner as determined by the chosen mapping structure.  
         [0019]     Shown in  FIG. 4  is a diagrammatic illustration of another operator station, denoted generally at  400 , embodying yet another embodiment of the operator interface system of the present invention. As shown, a single pedal  401  is utilized to control the acceleration and deceleration of the work machine. Specifically, fully displacing of the pedal  401  from the neutral position causes the work machine to accelerate at a pre-determined maximum acceleration. In other words, and as should be apparent to those of ordinary skill in such art, pedal  401  is used to initiate movement of the work machine. Conversely, releasing pressure on the pedal  401  causes a maximum pre-determined deceleration of the work machine. If desired, brake  112  may be used to actuate the conventional braking system so as to cause the work machine to stop. As in the previously described embodiments, the ECM  201  may contain the desired mapping structure to map the displacement of the pedal  401  with the desired velocity aspects of the work machine. The forward/reverse cane  107  may be utilized to effectuate locomotion of the work machine in either the forward or reverse directions.  
         [0020]     Shown in  FIG. 5  is a diagrammatic illustration of another operator station, denoted generally as  500 , embodying still yet another embodiment of the operator interface system of the present invention. In contrast with the previously described embodiment, ECM  201  is configured to provide for maximum acceleration unless otherwise directed by the work machine operator. As shown, the present embodiment incorporates a single pedal  501 , also coupled with a sensor  200 , that provides the aforementioned desired deceleration. Specifically, depressing pedal  501  causes pedal position data to be sent to the ECM  201  by the position sensor  200 . Upon receiving the position data, the ECM  201  decreases the velocity of the work machine at the pre-selected rate of deceleration corresponding to the pedal position. Upon releasing pressure on the pedal  501 , the work machine accelerates at the maximum pre-determined acceleration rate until the selected cruising speed is obtained. As in the previously described embodiment, the forward/reverse cane  107  may be used to selectively configure the work machine for forward or reverse travel. Also, the brake  112  may be coupled to the pedal  501  in the aforementioned manner so as to actuate the braking system when the pedal  501  has been depressed from its neutral position a pre-determined amount.  
         [0021]      FIG. 6  illustrates an exemplary transmission system, embodied herein as a hydrostatic continuously variable transmission  601 , which may be used with the embodiments of the operator interface system described herein. Such transmissions  601  are conventionally known and will not be elaborated upon in any greater detail than necessary to fully teach the present invention. The transmission  601  includes a fixed displacement hydrostatic motor  602  operable by a variable and reversible hydrostatic pump  603 . The reversible hydrostatic pump  603  is typically driven by the work machine engine (not shown). During operation, the speed of the engine is typically held constant with the forward and reverse ground speed of the work machine being varied through rotation of the pump swash plate  606 . The motor  602 , in turn, typically drives the work machine&#39;s axles (not shown).  
         [0022]     For illustrative purposes, the centered or neutral position of the swash plate  606  is as shown in  FIG. 6  and corresponds to the base or neutral position of pedal(s)  110 ,  111 ,  401 ,  501 . Displacement of the aforementioned pedal(s) causes the aforementioned displacement signals to be relayed to the ECM  201 . The ECM  201 , in turn, is coupled in a conventional manner to the transmission  601  and is operable, based on pedal position, to change the angle of the swash plate  606  which results in a flow of oil through the pump  603  and motor  602  combination. As should be apparent to those skilled in such art, the greater the change in angle of the swash plate  606 , the greater the speed of the motor  602  and, hence, the output speed of the transmission  601  is increased resulting in a greater ground speed of the work machine. As should be appreciated, the aforementioned mapping structures are adapted to control this rate of change of the swash plate, thereby effectively controlling the velocity, acceleration, deceleration and jerk of the work machine.  
         [0023]     The directional movement of the work machine is controlled by the direction of angular movement of the swash plate  606 . For example, a clockwise rotation of the swash plate  606  results in forward movement of the work machine; whereas, a counterclockwise rotation of the swash plate  606  results in reverse motion of the work machine. As should be apparent, for those single-pedal embodiments described above with reference to  FIGS. 4 and 5 , and for the  FIG. 1  embodiment in which both pedals  110 , 111  only control vehicle acceleration or deceleration, the forward/reverse cane  107  may coupled in a conventional manner to the swash plate  606  to control the swash plate&#39;s  606  direction of rotation. Alternatively, for the  FIG. 1  embodiment in which pedals  110 , 111  are used to control locomotion of the work machine&#39;s in a forward or reverse direction, the pedals  110 , 111  may be coupled in a convention manner to the swash plate  606  to effectuate this directional control.  
         [0024]     Alternatively, and with further reference to  FIG. 6 , each of the pedal(s)  110 ,  111 ,  401 ,  501  may be operatively coupled by a suitable linkage (not shown), in a conventional manner, to the swash plate  606 , thereby directly providing the swash plate  606  with the aforementioned positional control. As should be apparent, such an arrangement negates the necessity for the inclusion of the ECM  201  or sensors  200  (all shown in alternate detail in  FIG. 6 ). Accordingly, the speed and acceleration or deceleration of the work machine will be a function of the pedal position with respect to time. In addition, and as mentioned previously, the direction of rotation of the swash plate  606  may be either controlled by pedal(s)  110 , 111 , 401 , 501  or via the forward/reverse cane  107 . It is to be understood that the showing of a dual pedal arrangement with the transmission  601  in  FIG. 6  is exemplary only and that it is contemplated that any of the operator interface embodiments described herein can also be utilized.  
         [0000]     Industrial Applicability  
         [0025]     With reference to the drawings, and in operation, all embodiments of the operator interface system described herein provide a means for the operator to more easily and intuitively control various velocity aspects such as speed, acceleration, deceleration and jerk of a work machine through the use of either a single or dual pedal arrangement. Displacement of each pedal  110 ,  111 ,  401 ,  501  from its base or neutral position causes pedal positional date to be relayed to the ECM  201  which, in turn, operatively controls the various work machine systems such as the engine and transmission systems in order to control the aforementioned velocity aspects.  
         [0026]     Mapping structures are programmed into the ECM  201  and are used to map each pedal position with a desired velocity aspect response. In such manner, the operating characteristics of a particular type of work machine can be optimized to provide a smoother and more easily controlled ride. In addition, by allowing the operator to control the work machine by using either one or two pedals in contrast to various hand and foot operated operator interface devices simplifies the learning process for new operators.