Abstract:
An improved equipment guidance system and assembly is described comprising a top plate in releasable engagement with a drawbar of a towing vehicle, a supplemental or ancillary drawbar pivotable about a forward location and movable to an offset position left or right of center by a pair of pistons, and a bottom plate for attachment to the ancillary drawbar and the top plate. The pistons are controlled by a control box that dictates in concert the extension and retraction of the left and right pistons. A signal from the control box is generated from a plurality of sources. One example of a signal source is a tilt sensor that measures inclination relative to gravity. Another example of a signal source is an automatic “whiskers” crop row sensing wand system. Yet another example of a signal source can be generated manually from an operator of the towing vehicle.

Description:
RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 60/221,647, filed Jul. 28, 2000. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a guidance system for pull-type equipment, and more specifically, to a guidance system capable of adjusting the angle of a vehicle drawbar in connection with an implement as it is pulled across a surface. Furthermore, the guidance system allows an equipment operator an ability to alter the towing path of the implement while on-the-fly to account for gravitational forces acting laterally on the implement as it is towed across a surface having a non-horizontal grade or as may be necessary to avoid obstacles and the like. 
     2. Background of the Prior Art 
     Typical pull-type equipment is arranged in a manner such that a towing vehicle provides locomotion to a trailing implement provided to perform various functions. Agricultural pull-type equipment is designed to perform various functions on a field in which crops are planted, grown, and harvested, while other pull-type equipment is designed to perform other functions, such as grading a surface of snow or earth. In the case of agricultural pull-type equipment, it is highly desirable to work the soil or apply chemicals by maneuvering the equipment between rows of crops without disrupting the crops themselves. Row crops grown in fields with a generally flat grade pose little challenge to an operator once the equipment has been properly aligned such that the equipment provides its desired function without disturbing the crops. However, maintaining proper alignment of equipment as it travels through rows of crops becomes increasingly difficult in a field with a non-horizontal grade, such as a hillside, due to the forces of gravity acting on the equipment in a manner such that the trailing elements of the implement in-tow move laterally relative to the forward motion of the implement. 
     In the case of other pull-type equipment, it is highly desirable to manipulate the path of the implement in addition to that provided through steering the towing vehicle. Not withstanding instances where correction for gravity is the primary consideration, in other circumstances, it is desirable for an equipment operator to manipulate the path of the implement in-tow independent from the towing vehicle. Examples illustrating such circumstances include maneuvering the implement through a gate or opening, maneuvering over or under a viaduct or bridge, and manipulating the relative position of equipment during vehicle-implement connection, disconnection, and storage. 
     Attachment of an implement to a towing vehicle is commonly accomplished by providing an elongated neck portion of an implement for marriage to a drawbar located at the rear of a towing vehicle. The elongated neck allows the towing vehicle to change directions without interfering or coming into contact with the implement in-tow at a point other than the pivot point at which the vehicle drawbar is connected to the implement. 
     It is known in the art to provide adjustable drawbars capable of vertical height alteration. It is also known to provide drawbars extended to the rear of a vehicle capable of altering the fixed angular position of the drawbar. 
     Nevertheless there remains a longstanding need for improvements in adjustable drawbar assemblies. Such improvements result in guidance systems for pull-type equipment which will allow an equipment operator an ability to adjust the offset of the drawbar at an angle while underway. Typically, adjustments are necessary to correct the tendency of a towed implement to slide laterally down a grade when the equipment is moving in a forward direction. Further improvements would provide automatic corrective feedback mechanisms whereby a control module would sense a change in grade and relay a command to the drawbar assembly to correct the tendency of the towed implement to slide laterally down a grade when the equipment is moving in a forward direction. Improvements further still would allow an equipment operator an ability to manually maneuver the towed implement to avoid impact with an object in or near the path of the towed implement or to generally improve operator ability to manipulate the position of the towed implement. Further improvements would provide automatic corrective feedback mechanisms whereby a control module would sense the alignment of crop rows and relay a command to the drawbar assembly to maintain implement alignment with the crop rows. Improvements further still would provide a variety of drawbar signaling and feedback options, including, but not limited to, mechanically-derived input signaling, pendulum-derived input signally, mechanically-derived feedback signaling, ultrasonic-, ultraviolet-, and laser-derived feedback signaling. 
     SUMMARY OF THE INVENTION 
     An improved equipment guidance system and assembly is described comprising a drawbar in communication with a drawbar signaling means and in further communication with a drawbar feedback means such that the drawbar is adjustable left or right of center depending on towing vehicle-implement operating conditions and a comparison of the drawbar signal and the feedback signal. According to one aspect of the present invention, the improved guidance system and assembly is an integrated component of the drawbar a towing vehicle. According to another aspect of the present invention, the improved guidance system and assembly comprises a top plate in releasable engagement with a drawbar of a towing vehicle, a supplemental or ancillary drawbar pivotable about a forward location and movable to an offset position left or right of center by a pair of pistons, and a bottom plate for attachment to the ancillary drawbar and the top plate. The pistons are controlled by a control box that dictates in concert the extension and retraction of the left and right pistons. A signal from the control box is generated from a plurality of sources. 
     One example of a signal source is a tilt sensor that measures inclination relative to gravity. The response of the tilt sensor depends on the magnitude of gravity parallel to the sensor element. The output of the tilt sensor is automatically and constantly conveyed to the control box where a command is sent to electro-hydraulic valves that control the extension and retraction of the left and right pistons to correct for the measured tilt. Another example of a signal source is an automatic crop sensing wand system wherein flexible wires or “whiskers” are used to physically sense the row of crops to provide steering signal that is used to direct the towing vehicle between the rows. Whiskers monitor tractor alignment with row crops through a plurality of sensors the output of which is automatically and constantly conveyed to the control box where a command is sent to electro-hydraulic valves that control the extension and retraction of the left and right pistons to correct for the measured disparity measured by the whiskers. Other examples of signal sources include mechanically-derived input signaling and pendulum-derived input signaling. Yet another example of a signal source can be generated manually from an operator of the towing vehicle. The operator can direct the drawbar left or right by activating a handheld or mounted switch that signals the control box command to send a signal to the electro-hydraulic valves that extend and retract the left and right pistons to manipulate the position of the drawbar accordingly. 
     According to another aspect of the invention, drawbar feedback means comprises a smart cylinder in electronic feedback communication with the control box. Yet another aspect of the invention comprises a mechanically-derived signal as a feedback means, such as a lever or touch-sensitive wire. Other aspects of the drawbar feedback means comprise photoelectric, ultrasonic-, ultraviolet-, and laser-derived feedback signaling. 
     According to yet another aspect of the invention, there is provided an equipment guidance system on a towing vehicle for towing an implement comprising: 
     a drawbar pivotable about a forward location and movable to an offset position left or right of center; 
     a means for said ancillary drawbar adjustment; 
     a signaling means for directing ancillary drawbar adjustment; 
     said ancillary drawbar pivotable to an offset position between a substantially center position and a plurality of positions left of center; and 
     said ancillary drawbar pivotable to an offset position between a substantially center position and a plurality of positions right of center. 
     According to another aspect of the invention, there is provided for attachment to a drawbar of a towing vehicle an equipment guidance system for towing an implement comprising: 
     a top plate for releasable engagement of vehicle drawbar; 
     an ancillary drawbar pivotable about a forward location and movable to an offset position left or right of center; 
     a means for said ancillary drawbar adjustment; 
     a signaling means for directing ancillary drawbar adjustment; 
     a bottom plate for supporting said ancillary drawbar and said top plate; 
     said ancillary drawbar pivotable to an offset position between a substantially center position and a plurality of positions left of center; and 
     said ancillary drawbar pivotable to an offset position between a substantially center position and a plurality of positions right of center. 
     Preferably, said means for the ancillary drawbar adjustment comprises a pair of hydraulic cylinders in receptive engagement with the ancillary bar, wherein a first end of each cylinder is attached to said top plate at a position proximal to a forward portion of the assembly on either side of the ancillary bar, and wherein a second end of each cylinder is further attached to said ancillary bar at a position distal to a forward portion of the assembly on either side of the ancillary bar. 
     According to a another aspect of the invention, there is provided for attachment to a drawbar of a towing vehicle an equipment guidance system for towing an implement comprising: 
     a top plate for releasable engagement of vehicle drawbar; 
     an ancillary drawbar pivotable about a forward location and movable to an offset position left or right of center; 
     a means for said ancillary drawbar adjustment; 
     a signaling means for directing ancillary drawbar adjustment; 
     a bottom plate for supporting said ancillary drawbar and said top plate; 
     said ancillary drawbar pivotable to an offset position between a substantially center position and a plurality of positions left of center; and 
     said ancillary drawbar pivotable to an offset position between a substantially center position and a plurality of positions right of center. 
     said means for the ancillary drawbar adjustment comprises a pair of hydraulic cylinders in receptive engagement with the ancillary bar, wherein a first end of each cylinder is attached to the top plate at a position proximal to a forward portion of the assembly on either side of the ancillary bar, and wherein a second end of the cylinder is further attached to the ancillary bar at a position distal to a forward portion of the assembly on either side of the ancillary bar; and 
     a means for automatically adjusting said offset position according to a signal source in communication with a drawbar feedback signal. 
     Preferably, said means for automatically adjusting the offset position according to the grade of the ground on which the implement is being towed comprises a measuring means for measuring the grade level of said ground, wherein said measuring means is in communication with a control means for controlling said hydraulic cylinders acting in concert to adjust the offset of the ancillary drawbar rightward or leftward to adjust the on-the-fly orientation of the implement in-tow. 
    
    
     These and other aspects of the present invention will become apparent to those skilled in the art upon reference to the following specification and drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top plan view of an adjustable drawbar offset assembly in accordance with the teachings of the present invention. 
     FIG. 2 is a bottom plan view of the assembly of FIG.  1 . 
     FIG. 3 is a side elevational view as seen generally from line  3 — 3  in FIG. 1, and with a tractor drawbar shown in phantom. 
     FIG. 4 is a rear elevational view as seen generally from line  4 — 4  in FIG.  1 . 
     FIG. 5 is a front elevational view as seen generally from line  5 — 5  in FIG.  1 . 
     FIG. 6 is a perspective view of the assembly of FIG.  1 . 
     FIG. 7 is a top plan view of a control panel on an electronic control box that directs adjustment of the invention of FIG.  1 . 
     FIG. 8 is a wiring diagram of the electronic control box and cylinder feedback circuit of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As shown in the drawings, and referring in particular to FIG. 3, numeral  10  designates the adjustable drawbar assembly of the present invention. The assembly  10  generally comprises a top plate  12 , a bottom plate  14 , and an ancillary drawbar  16 . Top plate  12  is adapted for releasable engagement with a tractor drawbar  18  (shown in phantom). Forward mounting posts  20  and rearward mounting posts  22  are provided for attaching assembly  10  to tractor drawbar  18  by releasably engaging top plate  12 . In a preferred embodiment, posts  20  and  22  include threaded bolts  24  in threaded engagement with nut members  26 . In an alternate preferred embodiment, the assembly  10  further comprises friction plates (not shown) releasably attached to the top and bottom segments of bar  16  that contact plates  12  and  14 . In a preferred embodiment, the friction plates are constructed with an ultra-high molecular weight polyethylene compound. 
     Referring still to FIG. 3, forward mounting posts  20  further include forward spacer plate  28  and rearward mounting posts  22  further include rearward spacer plate  30 . Spacer plates  28  and  30  are provided to support tractor drawbar  18  in receptive engagement with assembly  10 . Forward plate bolts  32  and rearward plate bolts  34  are in threaded engagement with nuts  36 . Bolts  32  and  34  are provided for attaching top plate  12  and bottom plate  14 . Bolts  32  are further provided to fixedly engage a proximal end of actuators or hydraulic cylinders  38 . A distal end of hydraulic cylinder  38  is pivotally attached to ancillary drawbar  16  at cylinder mounting plate  40 . By extending and shortening the length of the cylinders  38 , an operator can adjust the degree of desired offset of ancillary drawbar  16  to the left or right of a central axis substantially defined by tractor drawbar  18  about central pivot post  42 . 
     Continuing to reference FIG. 3, hydraulic connectors  44  attach cylinders  38  to hydraulic fluid conduit  46  to provide hydraulic fluid to effectuate the movement of cylinders  38 . A lateral adjustment element  48  is supported by bracket  50 . Lateral adjustment element  48  is provided to manually adjust ancillary drawbar  16 . In a preferred embodiment, integral transducer  58  provides a drawbar position feedback (“DPF”) mechanism to an electric control box  60  (FIG. 7) to determine the relative position of cylinders  38 . However, only one of the cylinders  38  is fitted with transducer  58  (Bobalee Hydraulics, Laurens, IA). In alternate embodiments, relative cylinder positions are determined by a plurality of proximity sensors, such as ultrasonic, ultraviolet, or laser proximity sensors (not shown) providing DPF signaling to control box  60 . In a further alternate embodiment, relative cylinder position or drawbar position feedback is determined mechanically by a lever or other mechanical element (not shown) in physical communication with the cylinders  38  or drawbar  16 . 
     Referring now to FIG. 1, lateral adjustment element  48  further includes a tension adjustment element  52 . A plurality of holes  54  is provided to receive pins (not shown) that are inserted in holes  54  to define a maximum or limit offset position for the ancillary drawbar  16 . Implement receiving member  56  is provided to releasably engage an implement in-tow (not shown). 
     FIG. 7 shows generally a control panel for the electronic control box (“ECB”)  60  responsible for processing signals from a variety of sources and generating output to the cylinders  38 . The ECB is typically located in a cabin of the towing vehicle within reach and plain view of the operator. Configured to operate in a plurality of modes, the ECB is designed to process an array of input signaling to adjust the position of drawbar  16 . Drawbar graphic  62  is a pictorial representation of the drawbar  16  relative to top plate  12 . Pictorial drawbar  64  is shown in the centered position, whereas pictorial drawbar  66   a  shows (in phantom) a leftwardmost drawbar position and pictorial drawbar  66   b  shows (in phantom) a rightwardmost drawbar position. One of a plurality of LED lights on drawbar position display  68  is illuminated to represent the approximate position of drawbar  16  relative to top plate  12  as depicted in a range of positions from a leftwardmost position  66   a  to a rightwardmost position  66   b  as displayed on graphic  62 . 
     Referring still to FIG. 7, two-position toggle switch  74  turns the guidance system on and off. When the system is powered and “on,” indicator bulb  72  is illuminated. Three-position toggle switch  70  determines the source of input signal supplying the ECB  60 . When switch  70  is positioned in the “Auto Steer” mode  80   b , the ECB receives a signal from a row-crop sensing device commonly known as “whiskers.” When switch  70  is positioned in “Auto Level” mode  80   a , the ECB receives a signal from a ground level sensor mounted to the vehicle (not shown). Input signals for auto leveling and auto steering are generated from an automatic implement position-relative (“AIPR”) signal generator. In a preferred embodiment, a single axis tilt sensor is used (Crossbow Technology, Inc., San Jose, Calif.) to determine the grade or level of the ground and the tilt sensor is mounted inside the ECB  60 . The Crossbow tilt sensor uses a micro-machined acceleration-sensing element with a DC response to measure inclination relative to gravity. Tilt sensor response depends on the magnitude of gravity parallel to the sensor element. The output of the tilt sensor is an offset voltage plus the voltage response proportional to the amount of gravity measured by the sensor. In a preferred embodiment, the voltage response of the tilt sensor is proportional to the sine of the tilt angle. Accurately measuring tilt angle is accomplished by solving the following equation: Sin −1  ((V out −Zero Angle Voltage)/Sensitivity). For angles less than 20°, the sine function is approximated by a linear relationship between the V out  and the tilt angle in radians. Thus, the equation for angle in degrees is as follows: 180/((V out  −Zero Angle Voltage)/Sensitivity). When the angle is less than 20°, the error from linear approximation is less than 1%. Alternate embodiments of the invention utilize tilt sensors or ground level sensors having fluid, electrolytic, and pendulum-based processing (not shown). Further alternate embodiments utilize ultrasonic-, photoelectric-, and laser-derived positional and proximity signaling (not shown) to generate command signals and/or a feedback signals. One example of an ultrasonic proximity sensor or switch utilizes sonar-reflected sound (Siemens Energy &amp; Automation, Germany). 
     Positioning switch  70  in “Manual” mode  80   c  configures the system to act upon signals received from a hand-held or cabin-mounted control device (not shown). In a preferred embodiment, a hand-held toggle switch spring biased to the center is used. By toggling the switch in a leftward direction while in “Manual” mode, the drawbar  16  moves left. Upon release of the switch, the switch returns to the center position and the drawbar  16  follows-suit. By toggling the switch in a rightward direction while in “Manual” mode, the drawbar  16  moves right. Upon release of the switch, the switch returns to the center position and the drawbar  16  follows-suit. The position of the drawbar is observed directly or monitored by observing the illumination of one of a plurality of LED lights on drawbar position display  68  representing the approximate position of drawbar  16  relative to top plate  12  as depicted in a range of positions from a leftwardmost position  66   a  to a rightwardmost position  66   b  as displayed on graphic  62 . 
     Continuing with reference to FIG. 7, calibration egg  76  is used to calibrate the guidance system when operating in Auto Level mode. In a preferred embodiment, egg  76  includes a locking member  82 , a bullet level  78 , and a floating ball  84 . By rotating locking member  82  counter-clockwise, the floating ball is free to rotate. Calibrating the guidance system in Auto Level mode requires parking the vehicle on a level surface. The equipment operator calibrates the tilt sensor by manipulating the floating ball until an arrow is aligned with the direction of travel, and the bullet level bubble indicates “level.” Tightening locking member  82  in a clockwise rotation locks ball  84  in place and calibration is complete. Adjusting gain  86  to a plurality of positions between 11° and 22° enables an operator to approximate the grade on which the equipment is operating. Depending on the approximated slope and adjustment of gain  86 , the ECB  60  will accelerate or decelerate the speed at which the drawbar  16  moves leftward or rightward of center. A restrictor plate in the closed hydraulic system of the present invention limits hydraulic fluid flow to 2 gal/min, resulting in drawbar movement to and from the center position to the leftwardmost or rightwardmost position at a maximum travel rate of around 2 to 3 seconds. 
     With reference to FIG. 8, electronic control box (“ECB”)  88 , in a preferred embodiment, comprises a dual coil comparator (High Country Tek, Nevada City, Calif.), which drives simple “on/off” valves to close the loop on two inputs. ECB  88  is powered from the battery  90  at power supply  94  and is grounded to ground  172  at power corn  104 . Manual mode switch  138  overrides the automatic level and steering circuits when manual mode circuit  140  is closed. Likewise, when switch  138  is in the automatic position, automatic mode circuit  142  is closed. Generally, the ECB  88  drives coil A  122  when the control input [derived from coil A (+)  96  and coil A (−)  100 ] is greater than the cylinder feedback input [derived from cylinder feedback com  106 , cylinder feedback voltage  108 , and cylinder feedback reference voltage  110 ], and drives coil B  124  when the control input [derived from coil B (+)  98  and coil B (−)  102 ] is less than the cylinder feedback input [derived from cylinder feedback corn voltage  106 , cylinder feedback voltage  108 , and cylinder feedback reference voltage  110 ]. Auto steer switch  126  closes either auto level circuit  126   a  (position  80   a  in FIG. 7) or auto steer circuit  126   b  (position  80   b  in FIG.  7 ). When switch  126  is positioned for auto steer (position  80   b  in FIG.  7 ), it receives signal input from the whiskers at auto steer inputs  128 ,  130 . When switch  126  is positioned for auto level (position  80   a  in FIG.  7 ), it receives signal input from X-axis voltage  172  of tilt sensor  160 . Tilt sensor  160  is powered from the battery  90  at power supply  168  and is grounded at ground  170 . X-axis voltage  172  from tilt sensor  160  reaches gain potentiometer (10 K ohm)  148  as 22° setting input  152  and compares it to 11° setting  150  to generate a “loop” signal to decelerate drawbar  16  movement when the 11° setting  150  is activated by gain  86  (FIG. 7) on ECB control panel  60  (FIG.  7 ). 
     Referring still to FIG. 8, in the automatic modes, cylinder feedback potentiometer  156  (5 K ohm POT, 1 K ohm/inch) relays cylinder feedback voltage  108  to feedback reference voltage  110  and cylinder feedback corn voltage  106 . Cylinder feedback voltage  108  further signals voltage input  166  of the LED display  158  and illuminates LED light bar  68  (FIG. 7) to show the equipment operator a graphic representation of the position of drawbar  16  on ECB control panel  60  (FIG.  7 ). LED display  158  is powered from the battery  90  at power supply  162  and is grounded at signal corn  164 . Command reference voltage  116  is applied across resistor D  144  (15 K ohm, ¼ watt, 5%) whereas command corn voltage  112  flows through resistor C  144  (15 K ohm, ¼ watt, 5%). When manual mode circuit is closed, manual override potentiometer (10 K ohm)  134  relays a signal from command voltage  114  through resistors A and B,  132 ,  136  (1.5 K ohm, ¼ watt, 5%) returning to the ECB  88  at feedback reference voltage  110  and feedback com voltage  106 . When automatic mode circuit is closed, signals from command voltage  114  flow through switch  138  through resistors C and D,  144 ,  146  (15 K ohm, ¼ watt, 5%) returning to the ECB  88  at command corn voltage  112  and command reference voltage  116 . Error indicators  118   120  can be configured to detect out of range inputs or an open or shorted valve coil. 
     The ECB  88  further comprises a serial communications port (not shown) for customizing the individual parameters with a PC using configuration software. In a preferred embodiment, smart cylinder solenoid valves (Command Control Corp., Elgin, Ill.) are three-way, two position, spool type, direct acting, solenoid operated, directional control valves (not shown), and load holding valves (Command Control Corp., Elgin, Ill.) are direct acting, screw in cartridge style, poppet type, adjustable, pilot assisted, hydraulic counterbalance valves. In an alternate preferred embodiment, both cylinders are standard hydraulic cylinders and drawbar position feedback (“DPF”) is attained through an alternate means (switches or sensors utilizing ultrasonic-, photoelectric-, and laser-derived positional and proximity signaling to generate a feedback signal) (not shown). 
     The foregoing description and drawings comprise illustrative embodiments of the present inventions. The foregoing embodiments described herein may vary based on the ability, experience, and preference of those skilled in the art. The foregoing description and drawings merely explain and illustrate the invention, and the invention is not limited thereto. Those skilled in the art who have the disclosure before them will be able to make modifications and variations therein without departing from the scope of the invention.