Abstract:
A tractor includes an electronic tractor controller. A baler includes an electronic baler controller. The baler controller submits a halt signal to the tractor controller when a bale size is equal to or exceeds a first predetermined size. The baler controller generates a tractor halt signal in response to certain conditions of the baler system and the tractor controller preventing tractor motion in response to the halt signal. When the baler controller is generating the halt signal, tractor motion is enabled if the operator commands the tractor to move by manipulating the command device, and within a certain time period of said command being issued, the baler controller generates a tractor motion enabling signal in response a status of the baler system. When the baler controller is generating the halt signal, tractor motion is enabled if the operator moves the tractor command device in a special manner.

Description:
This application is a Continuation of U.S. patent application Ser. No. 12/613,814, filed Nov. 6, 2009, which is incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a tractor-implement control system. 
     BACKGROUND OF THE INVENTION 
     Agricultural tractors are used in combination with implements which are towed by the tractor. A tractor/baler combination is used in agriculture to take up crop lying or standing on a field and to press and bind it to a bale. A tractor/baler combination with automatically controlled operations is described in U.S. Pat. No. 7,404,355, issued in July 2008 and assigned to the assignee of the present application. 
     When a tractor is pulling a round baler through a field it is necessary to keep the tractor stationary while the bale is ejected and the gate or rear door is closed. Many times an operator will re-initiate motion before the gate is fully closed and latched. This can prevent the cycle from completing successfully. With a baler, material may get caught in the gate and prevent it from fully closing. This results in lost time while the gate is reopened, the debris is removed, and the gate is closed again. Also, if the bale ejection cycle is initiated before the bale is fully wrapped, the bale may unwrap after the ejection resulting in either loss of the material or loss of time to re-bale the material. 
     With an automated system, the machine can determine when it is appropriate to move on to the next step of the operation. For example, eject the bale and/or re-initiate motion once the bale has been ejected. The automated system thereby provides additional opportunities to ensure that the operation is completed successfully in the correct order. In the case of ejecting a bale prematurely, the automated system can initiate this only after the bale wrapping process has been completed. For the case of re-initiating motion before the bale ejection cycle is complete, it can prevent the tractor from moving even if the operator attempts to start motion. It is not always feasible for an automated system to fully encompass all of the many exceptions to the “normal” field operation/sequences. For these cases, it would be desirable to provide the operator a relatively simple way to override the mistake proofing features. 
     SUMMARY OF THE INVENTION 
     Accordingly, an object of this invention is to provide an improved method of controlling a tractor-implement combination. 
     A further object of the invention is to provide the operator with a relatively simple way to override the mistake proofing features of a tractor-implement automatic control system. 
     These and other objects are achieved by the present invention, wherein a method is provided for controlling a combination of a tractor and an implement, such as a baler, coupled to the tractor. The tractor includes ground engaging drive wheels driven by an engine which is coupled to the drive wheels by a power transmission, an operator movable command device and a tractor controller operable to control tractor motion in response to operation of the command device. The baler includes a baler system for receiving crop, for baling crop into a bale and for ejecting a bale from the baler, a baler controller coupled to the baler system and to the tractor controller. The method includes the baler controller generating a tractor halt signal in response to certain conditions of the baler system and the tractor controller preventing tractor motion in response to the halt signal. The method also includes, when the baler controller is generating the halt signal, enabling motion of the tractor if the operator issues a command for the tractor to move by manipulating the command device, and within a certain time period of said command being issued, the baler controller generates a tractor motion enabling signal in response a status of the baler system. 
     The method further includes, when the baler controller is generating the halt signal, enabling motion of the tractor if the operator issues a command for the tractor to move by manipulating the command device, and within a certain time period after said command being issued, the baler controller generates a tractor motion enabling signal in response a status of the baler system. 
     The method also includes, when the baler controller is generating the halt signal, enabling motion of the tractor if the operator issues a command for the tractor to move by manipulating the command device, and within a certain time period before said command being issued, the baler controller generates a tractor motion enabling signal in response a status of the baler system. 
     The method further includes when the baler controller is generating the halt signal, enabling motion of the tractor if the operator moves the tractor command device in a special manner. 
     The automated system provides several opportunities to prevent operator mistakes during normal operation. The operator still has the possibility to override the automation system using the normal controls in an intuitive manner. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a simplified side view of a tractor with a round baler coupled thereto; 
         FIG. 2  is schematic diagram of a control system the tractor/baler combination of  FIG. 1 ; and 
         FIG. 3  is a logic flow diagram of an algorithm executed by the control system of  FIG. 2 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  shows a tractor  10  and a round baler  12  coupled to a tractor drawbar  15  by means of a baler drawbar  14 . The tractor  10  is supported on a frame  18 , which is supported on ground engaging steerable front wheels  20  and ground engaging driven rear wheels  22 . The frame  18  supports a cab  24  which includes an operator&#39;s station  26 . The tractor  10  includes a conventional power take-off or PTO shaft  56  which is connected to a drive shaft  54  of the baler  12 . 
     The baler  12  includes a baler frame  114  supported on wheels  116 . The frame  114  supports a baler system  113  which includes a baling chamber  112  surrounded by aprons  118  guided around rollers  120 . An arm  135  supporting a roller  122  can be moved upwardly and downwardly by means of a hydraulic cylinder  124 . The hydraulic cylinder  124  is connected to the arm  135  via a lever  136  that is pivotally about a horizontal axis  137 . The hydraulic cylinder  124  thus determines the tension of the aprons  118 . Below the front edge of the baler  12 , a crop receiving pickup  126  with tines moving or rotating around a transverse axis is followed in a crop flow direction by a conveyor belt  128 . The conveyor belt  128  could also be replaced by a rotor (not shown), or a rotor could be inserted in the crop flow direction between the crop receiving means and the conveyor belt  128 . Instead of the pickup, any other suitable crop receiving means could be used, like mowing and conveying units. The crop receiving means  126  collects crop lying in a swath  130  of grass, hay or straw on the field and feeds it into the baling chamber  112 . The aprons  118  define a baling chamber  112  of a variable size. The aprons  118  are set into motion in their longitudinal direction during a baling process, since one or more of the rollers  120  is rotatively driven. The crop introduced into the baling chamber  112  is thus also rotating during baling, while the size of the baling chamber  112  increases over time since the bale causes arm  135  to move downwardly against the force of the cylinder  124 . 
     A rear door  132  is pivotally mounted to an upper rear location of the frame  114  at an axis  134  extending transversely to the forward direction of the tractor  10  and the baler  12 . A door actuator  138  in the form of a hydraulic cylinder is mounted with one end to the frame  114  and with a second end to the rear door  132 . The rear door  132  supports the rollers  120  surrounding the rear part of the baling chamber  112 . Actuator  138  is connected to the rear door  132  such that it can pivot the rear door  132  upwardly (in  FIG. 1  counter-clockwise) around axis  134  to be able to eject a bale from the baling chamber  112 . 
     A rear door sensor  140  is mounted at the lower rear end of the baler frame  114  close to the lower front edge of the rear door  132 . Sensor  140  senses whether the rear door  132  is closed or not by means of a switch (ot shown) actuated by the rear door  132 . 
     Three bale size sensors  144  connected to the baler processor  110  are distributed over the width of the baling chamber  112 . They sense the distance to the surface of the bale and/or of aprons  118  abutting the bale surface and provide thus information about the bale diameter at their respective location along the width of the bale. A first one of the bale size sensors  144  is assigned to a position close to the left edge of the baling chamber  112 . A second one of the bale size sensors  144  is assigned to a position close to center of the baling chamber  112 . A third one of the bale size sensors  144  is assigned to a position close to the right edge of the baling chamber  112 . 
     A wrapping material dispenser  146  is located close to the baling chamber  112 . It is connected to the baler controller  110  and dispenses, once instructed so by the baler controller  110 , a wrapping material like twine, ribbon, net or wrapping sheet to the baling chamber  112 . The rotating bale catches or pulls the wrapping material such that it is then wrapped around the bale. A wrapping material movement sensor  148  is interacting with the wrapping material dispenser  146  and senses whether the bale is pulling the wrapping. The crop receiving means  126  can be lifted by a hydraulic cylinder  152 . 
     Sensors  156  and  158  provide information about the position of the cylinders  152 ,  124 , respectively to the baler controller  110 . Another sensor  157  senses the position of the door actuator  138  or of the gate or door  132 . 
     Referring now to  FIG. 2 , the tractor baler control system  160  includes an electronic microprocessor-based baler control unit  162  which is mounted on the baler  12  and which is connected to bale size sensors  144 , to gate closed sensor  140  and to wrap sensor  148 . Control unit  162  is connected via a convention data bus  161 , such as a CAN bus, to a tractor electronic control system  164 . 
     The tractor electronic control system  164  preferably includes one or more conventional microprocessor-based electronic control units (not shown) which control various tractor systems and components, such as, but not limited to, the brakes  166 , the clutch  168 , the engine  170  and the transmission  172 . The engine  170  drives the transmission  172  which drives the wheels  22 . 
     The transmission  172  is preferably a known infinitely variable transmission or IVT. The transmission  172  could be a known power shift transmission (not shown), or any other type of commercially available transmission suitable for use in a tractor. For example, the transmission  172  can, for example, be a purely hydraulic transmission with a hydraulic pump driven the clutch  168  and a hydraulic motor or hydrostatic transmission (not shown) moving the wheels  22 , wherein the transmission ratio of the gear can be changed by adjusting the swash plates (not shown) of the pump (not shown) and/or of the motor (not shown). Alternatively, the transmission could be a multistage mechanical gearbox with a torque converter (not shown) connected in series, such as used in passenger cars, or a mechanical gearbox (not shown) with a sufficient number of transmission stages and an automatically switched clutch (not shown) or planet gears (not shown) and friction clutches (not shown). Alternatively, the transmission  172  could be have step-less adjustable gearing, such as V-belts (not shown) that rotate around pulleys (not shown) with adjustable diameters, or with a mechanical and a hydraulic (or electrical) drive path, wherein a planetary transmission (not shown) comprises an element driven mechanically with a fixed or stepwise variable speed and one driven hydraulically or electrically with variable speed, and the third element (not shown) is used for output. A combination of several of the mentioned transmissions would also be conceivable. 
     An interface/display unit  174  is connected to the control system  164  through the CAN bus  161 . The control system  164  receives transmission command signals from a known direction reverser control  176  which has a control lever or command device  178  movable in a “H” shaped gate or slot  180  to neutral N, center park CP, park P, forward F and reverse R positions. The control system  164  also receives signals from a clutch pedal sensor  182  coupled to clutch pedal  183 , a brake pedal sensor  184  coupled to brake pedal  185 , a wheel speed sensor  186 , an operator presence sensor  188  coupled to seat  189 , and a selective control valve (SCV) unit  190 . The SCV unit  190  can be manipulated by the operator to control functions on the baler, such as the rear door or gate  132 . 
     Referring now to the flow chart of  FIG. 3 , the controller system  164  executes an algorithm  200 . The conversion of the above flow chart into a standard language for implementing the algorithm described by the flow chart in a digital computer or microprocessor, will be evident to one with ordinary skill in the art. 
     The algorithm begins at step  202  when the tractor control system is in an automatic mode. 
     Step  204  directs control to step  206  if the baler controller  162  has requested stopping of the tractor or has issued a halt signal, else step  204  repeats. 
     Step  206  generates a reduce speed command that causes the control system  164  to slow down the tractor and directs control to step  208 . 
     Step  208  directs control to step  248  if an automation exit condition exists, else to step  210 . An automation exit condition can exist for a variety of reasons, such as when the operator generates an override command, the operator is out of the seat, there is a system fault, there is a loss of communication in the system, etc. 
     Step  210  directs control to step  212  if the tractor has stopped, else back to step  206 . 
     Step  212  directs control to step  214  if the clutch or brakes have been used to stop the tractor  10  and the reverser lever  178  is in its forward position, else to step  222 . 
     Step  214  generates a hold zero speed command and directs control to step  216 . 
     Step  216  directs control to step  248  if an automation exit condition exists, else to step  218 . 
     Step  218  directs control to step  220  if the reverser lever  178  is in its forward position, else to step  222 . 
     Step  220  directs control to step  214  if the clutch and/or the brakes are still pressed, else to step  238 . 
     Step  222  establishes an “automatic stop state” and generates a hold zero speed command and directs control to step  224 . 
     Step  224  directs control to step  248  if an automation exit condition exists, else to step  226 . 
     Step  226  directs control to step  238  if the operator commands tractor motion and operator presence is detected by sensor  188 , else to step  228 . 
     Step  228  directs control to step  230  if the clutch and/or the brakes are still pressed, else to step  222 . 
     Step  230  generates a hold zero speed command and directs control to step  232 . 
     Step  232  directs control to step  248  if an automation exit condition exists, else to step  234 . 
     Step  234  directs control to step  236  if the clutch and/or the brakes are still pressed, else to step  222 . 
     Step  236  directs control to step  214  if the operator commands tractor motion and operator presence is detected by sensor  188 , else to step  238 . 
     Step  238  establishes an armed state, and sets the tractor speed based on the speed requested by the baler  12  and an operator adjusted speed limit (set how?) and directs control to step  240 . Typically, the operator sets the speed limit with the traditional operator controls. The speed limit is the speed that the tractor would be going if it were in manual control. 
     Step  240  directs control to step  248  if an automation exit condition exists, else to step  242 . 
     Step  242  directs control to step  250  if the tractor wheel speed is greater than a threshold (such as 0.5 kph, for example) and the speed requested by the baler is greater than zero, else to step  244 . 
     Step  244  directs control to step  222  if more than a certain time period (such as 1 second) has expired since step  238  was executed and the speed requested by the baler  12  is less than a threshold (such as 0.5 kph, for example), else to step  246 . 
     Step  246  directs control to step  222  if the tractor wheel speed is less than a threshold (such as 0.5 kph, for example) and the tractor has been unable to reach the threshold speed within a certain time period (such as 0.5 seconds), else to step  238 . 
     Step  248  ends automatic control of the tractor  10  so that the operator can manually control the tractor speed with the reverser lever  178 . 
     Step  250  ends this subroutine and the tractor  10  is allowed to move under automatic control. 
     As a result, the algorithm  200  operates to perform the following method. The baler controller  162  generates a tractor halt signal in response to certain conditions of the baler system  113 , such as when the gate  132  is open, and the tractor control system  164  prevents tractor motion in response to the halt signal. When the baler controller  162  is generating the halt signal, the tractor control system  164  enables motion of the tractor  10  if the operator issues a command for the tractor to move by manipulating the command device  178 , and within a certain time period, before or after, of the command being issued, the baler controller  162  generates a tractor motion enabling signal in response a status of the baler system  113 . 
     With this method the tractor  10  remains stationary while the implement  12  is requesting zero (0) speed. Once the implement  12  requests non-zero speed, the operator must move the reverser lever  178  from center park to forward to re-initiate forward motion. If the operator does this before the implement  12  requests a non-zero speed, motion will not be initiated and the reverser lever  178  must be cycled again after the implement  12  requests a non-zero speed. If the operator feels it is necessary to begin moving before the implement  12  is ready, the reverser lever  178  can be moved to a position other than forward or center park (e.g. reverse, neutral, or corner park) and the tractor  10  will respond to this and subsequent commands (exits automation). This differs from the use of the SCV lever  190  because moving the reverser lever  178  between forward and center park is part of the “normal” behavior to re-initiate forward motion. In addition, if the brake  166  and/or clutch  168  were activated during stopping, releasing them will result in the same behavior as moving the reverser lever  178  from center park to forward. When the capability is provided by the transmission  172 , it will go to powered zero while stopped. When this capability is not available, the transmission  172  will go to neutral during stop and to park if the clutch  168  is released prematurely. 
     While the present invention has been described in conjunction with a specific embodiment, it is understood that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. For example, the invention would be applicable to a tractor-implement combination where the implement is an implement other than a baler. The invention would also be applicable to a tractor in combination with any type of auxiliary control unit, such as a GPS unit or a guidance system, which can be connected to the tractor control system and which can cause the tractor control system to stop the tractor under certain conditions. Accordingly, this invention is intended to embrace all such alternatives, modifications and variations which fall within the spirit and scope of the appended claims.