United States Patent [19J
`Gfroerer et al.
`
`[54] METHOD AND APPARATUS FOR
`CONTROLLABLY AVOIDING AN
`OBSTRUCTION TO A COLD PLANER
`
`[75]
`
`Inventors: Gerry T. Gfroerer, New Hope;
`Michael W. Netka, Mound; Mario J.
`Souraty, Plymouth, all of Minn.
`
`[73] Assignee: Caterpillar Paving Products Inc.,
`Minneapolis, Minn.
`
`[21] Appl. No.: 09/241,198
`
`[22] Filed:
`
`Feb. 1, 1999
`
`Related U.S. Application Data
`[60] Provisional application No. 60/073,467, Feb. 2, 1998.
`
`Int. Cl? ............................. E01C 23/16; EOlC 23/07
`[51]
`[52] U.S. Cl. ............................ 404/84.05; 404/93; 404/94
`[58] Field of Search .................................. 404/75, 90, 91,
`404/92, 93, 84.05, 84.2, 84.5, 94; 299/39
`
`[56]
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`111111
`
`1111111111111111111111111111111111111111111111111111111111111
`US006152648A
`[11] Patent Number:
`[45] Date of Patent:
`
`6,152,648
`Nov. 28, 2000
`
`4,943,119
`5,318,378
`5,607,205
`5,893,677
`
`7/1990 Zarniko eta!. ........................... 299/39
`6/1994 Lent .......................................... 404/75
`3/1997 Burdick et a!. ........................ 299/39.6
`4/1999 Haehn eta!. ............................. 404/90
`
`FOREIGN PATENT DOCUMENTS
`
`WO 96/39562
`
`6/1995 WIPO ............................... E02F 9/24
`
`Primary Examiner-Eileen D. Lillis
`Assistant Examiner-Raymond WAddie
`Attorney, Agent, or Firm-Steven G. Kibby; Byron G. Buck
`
`[57]
`
`ABSTRACT
`
`A jump and return to grade function provides a means by
`activation of a switch to rapidly raise a milling machine to
`avoid an obstacle, then return the machine to the previous
`milling position. When the jump function is activated, the
`legs are extended at full speed, causing the machine to rise.
`In the return to grade function, the legs are retracted at
`controlled speeds until the previous milling depth is reached
`or the switch is released.
`
`3,929,377 12/1975 Weaver et a!. ............................ 299/39
`
`20 Claims, 9 Drawing Sheets
`
`10
`I
`
`89
`
`CONTROLLER
`
`99
`
`30
`
`I
`
`97
`
`20
`
`21
`
`JUMP
`
`9818
`
`CONTROL
`CONSOLE
`
`RETURN
`TO
`GRADE
`
`Page 1 of 16
`
`CATERPILLAR EXHIBIT 1110
`
`

`

`U.S. Patent
`
`Nov. 28, 2000
`
`Sheet 1 of 9
`
`6,152,648
`
`F..I.g_l_
`
`30
`I
`
`50
`
`28
`
`10
`I
`
`16
`
`20
`
`70
`
`21
`
`26
`
`CONTROLLER
`
`JUMP
`
`99
`
`98
`
`CONTROL
`CONSOLE
`
`RETURN
`TO
`GRADE
`
`Page 2 of 16
`
`

`

`U.S. Patent
`
`Nov. 28, 2000
`
`Sheet 2 of 9
`
`6,152,648
`
`F..:t.g_2_
`
`1201
`
`1202
`
`READ INITIAL DELAY
`VALUE, MAXIMUM DELAY
`VALUE, CROSS SLOPE
`MAXIMUM VALUE AND
`CROSS SLOPE MINIMUM
`VALUE FROM MEMORY
`
`HAS
`INITIALIZATION
`DELAY
`PASSED
`
`1203
`NO
`
`IS
`CROSS
`SLOPE SENSOR
`SIGNAL WITHIN
`RANGE
`
`1204
`NO
`
`1205
`
`1207
`
`SET OUTPUT SIGNALS
`TO RIGHT, LEFT, AND
`REAR LEGS TO A
`VALUE REPRESENTATIVE
`OF NO LEG MOVEMENT
`
`SET OUTPUT SIGNALS
`TO RIGHT, LEFT, AND
`REAR LEGS TO A
`VALUE REPRESENTATIVE
`OF MAXIMUM RAISING
`SPEEDS
`
`1206
`
`Page 3 of 16
`
`

`

`U.S. Patent
`
`Nov. 28, 2000
`
`Sheet 3 of 9
`
`6,152,648
`
`201
`
`READ THE RETURN TO
`GRADE DISABLE FLAG
`AND MAX. AND MIN. CROSS
`SLOPE VALUES
`
`202
`
`204
`
`SET ALL LEG
`COMMANDS TO ZERO
`
`210
`
`DECREMENT
`COUNTER BY 1
`
`REAR LEGS
`ABOVE AUTO
`STOP
`
`212
`
`SET THE LOWER
`REAR LEGS
`COMMAND TO RAPID
`LOWERING
`
`213
`
`214
`
`SET THE RETURN TO
`CONTINUE AT
`GRADE COUNTER TO
`ZERO AND SET THE 1----~ "RTNTOGRD 1"
`REAR LEG COMMAND
`TO ZERO
`
`Page 4 of 16
`
`

`

`U.S. Patent
`
`Nov. 28, 2000
`
`Sheet 4 of 9
`
`6,152,648
`
`F..I.g_3b_
`
`CONTINUED
`FROM
`"RTNTOGRD 1"
`
`214
`
`218
`
`219
`
`CONTINUED
`AT
`"RTNTOGRD 4"
`
`SET RIGHT AND LEFT
`FRONT LEG
`COMMANDS TO ZERO
`217
`
`224
`
`NO
`~----------~
`
`226
`
`CONTINUED
`AT
`"RTNTOGRD 5"
`
`227
`
`228
`
`231
`
`232
`
`CONTINUED
`AT
`"RTNTOGRD 6"
`
`Page 5 of 16
`
`

`

`U.S. Patent
`
`Nov. 28, 2000
`
`Sheet 5 of 9
`
`6,152,648
`
`CONTINUED
`FROM
`"RTNTOGRD 2"
`
`223
`
`235
`
`236
`
`SET RIGHT LOWER
`>---~ COMMANDTOSLOW
`SPEED AND CALL LEFT
`AUTO SLOPE
`
`238
`
`239
`
`SET RIGHT AND LEFT
`>---~ LOWER COMMANDS
`TO SLOW SPEED
`
`241
`
`SET RIGHT AND LEFT
`~-~ LOWER COMMANDS
`TO SLOW SPEED
`
`243
`
`SET LEFT SIDE LOWER
`TO ZERO AND RIGHT
`SIDE LOWER TO SLOW
`SPEED
`
`244
`
`Page 6 of 16
`
`

`

`U.S. Patent
`
`Nov. 28, 2000
`
`Sheet 6 of 9
`
`6,152,648
`
`__ :..:z:.._'-=' - 3 cf-
`
`CONTINUED
`FROM
`"RTNTOGRD 3"
`
`224
`
`246
`
`SET RIGHT LOWER
`COMMAND TO ZERO
`AND CALL LEFT
`AUTO SLOPE
`
`249
`
`SET RIGHT AND LEFT
`LOWER COMMANDS
`TO ZERO
`
`252
`
`SET LEFT LOWER
`COMMAND TO SLOW
`SPEED AND RIGHT
`LOWER TO ZERO
`
`254
`
`SET RIGHT AND LEFT
`LOWER COMMANDS
`TO ZERO
`
`253
`
`NO
`
`Page 7 of 16
`
`

`

`U.S. Patent
`
`Nov. 28, 2000
`
`Sheet 7 of 9
`
`6,152,648
`
`CONTINUED
`FROM
`"RTNTOGRD 4"
`
`219
`
`304
`
`SET LEFT LOWER
`COMMAND TO SLOW ~----~
`SPEED AND CALL
`RIGHT AUTO SLOPE
`307
`
`SET LEFT LOWER
`COMMAND TO SLOW
`SPEED AND CALL
`RIGHT AUTO SLOPE
`
`310
`
`SET LEFT LOWER
`COMMAND TO ZERO
`SPEED AND CALL
`RIGHT AUTO SLOPE
`
`308
`
`311
`
`314
`
`SET LEFT LOWER
`COMMAND TO FULL
`SPEED AND CALL
`RIGHT AUTO SLOPE
`WITH CROSS
`COUPLING
`
`SET LEFT LOWER
`COMMAND TO SLOW
`SPEED AND CALL
`RIGHT AUTO SLOPE
`
`316
`
`SET LEFT LOWER
`COMMAND TO MEDIUM I---~
`SPEED AND CALL
`RIGHT AUTO SLOPE
`WITH CROSS
`COUPLING
`
`318
`
`Page 8 of 16
`
`

`

`U.S. Patent
`
`Nov. 28, 2000
`
`Sheet 8 of 9
`
`6,152,648
`
`CONTINUED
`FROM
`"RTNTOGRD 5"
`
`226
`
`325
`
`SET RIGHT AND LEFT
`LOWER COMMAND
`TO SLOW SPEED
`
`320
`
`SET RIGHT AND LEFT
`LOWER COMMANDS
`TO SLOW SPEED
`
`323
`
`SET RIGHT AND LEFT
`LOWER COMMANDS
`TO ZERO SPEED
`
`Page 9 of 16
`
`

`

`U.S. Patent
`
`Nov. 28, 2000
`
`Sheet 9 of 9
`
`6,152,648
`
`F..I.g-3g_
`
`CONTINUED
`FROM
`"RTNTOGRD 6"
`
`232
`
`289
`
`SET RIGHT LOWER
`COMMAND TO FULL
`SPEED AND CALL LEFT
`AUTO SLOPE WITH
`CROSS COUPLING
`
`291
`
`294
`
`SET RIGHT LOWER
`COMMAND TO MEDIUM
`SPEED AND CALL LEFT
`AUTO SLOPE WITH CROSS
`COUPLING
`293
`
`SET RIGHT AND LEFT
`>---~ LOWER COMMANDS
`TO SLOW SPEED
`
`297
`
`298
`
`SET RIGHT AND LEFT
`LOWER COMMANDS
`TO FULL SPEED
`
`SET RIGHT AND LEFT
`LOWER COMMANDS
`TO SLOW SPEED
`
`SET RIGHT LOWER
`COMMAND TO SLOW
`'------~ SPEED AND LEFT
`LOWER COMMAND
`TO ZERO SPEED
`
`300
`
`302
`
`Page 10 of 16
`
`

`

`6,152,648
`
`1
`METHOD AND APPARATUS FOR
`CONTROLLABLY AVOIDING AN
`OBSTRUCTION TO A COLD PLANER
`
`This application claims the benefit of prior provisional 5
`patent application Ser. No. 60/073,467 filed Feb. 2, 1998.
`
`2
`tion as was being milled before the obstruction. It is also
`desirable to have a method of controlling the operation of a
`cold planer so that the milling depth before the obstruction
`and after the obstruction is the same.
`The present invention is directed to overcoming one or
`more of the problems as set forth above.
`
`TECHNICAL FIELD
`
`DISCLOSURE OF THE INVENTION
`
`This invention relates generally to an automatic control
`process and apparatus for controlling a roadway planer and 10
`more particularly to an automatic control process and appa(cid:173)
`ratus for controlling a roadway planer in avoiding an
`obstruction during roadway milling operations.
`
`BACKGROUND
`
`Roadway planers, also known as pavement pro filers, road
`milling machines or cold planers, are machines designed for
`scarifying, removing, mixing or reclaiming, material from
`the surface of bituminous or concrete roadways and similar
`surfaces. These machines typically have a plurality of tracks
`or wheels which support and horizontally transport the
`machine along the surface of the road to be planed, and have
`a rotatable planing cylinder that is vertically adjustable with
`respect to the road surface.
`On cold planers that integrate the machine chassis with
`the planing cylinder, as described in U.S. Pat. No. 4,186,968,
`issued Feb. 5, 1980, to Robert M. Barton and currently
`assigned to the assignee of the present invention, or those
`similar to the cold planer described in U.S. Pat. No. 4,929,
`121 issued May 29, 1990 to Kevin C. Lent et al. and
`assigned to the assignee of the present invention, raise or
`lower the entire chassis to control the depth of cut of the
`cutting bits into the ground surface. If the cutting bits strike
`a high density obstruction, such as a manhole cover or
`railroad track during the planing operation, the bits on the
`planing cylinder can be damaged or an event known as a
`"kickback" can occur.
`When a kickback event occurs, the planing cylinder on a
`typical down-cutting machine will attempt to rise up out of
`the cut. In a similar manner, changes in material density can
`cause the chassis on an up-cutting machine to also rise up
`out of the cut. If the cold planer is operating with an
`automatic grade control system, such as the portable string
`line system described in U.S. Pat. No. 4,270,801 issued Jun.
`2, 1981 to George M. Swisher, Jr. et al, the automatic grade
`control, sensing that the machine is above the desired grade,
`will attempt to lower the chassis by retracting the supporting
`strut members, leaving the machine principally supported on
`the rotor. In this position, the machine cannot be steered or 50
`braked because of insufficient contact between the strut
`mounted tracks, or wheels, and the ground. In this condition,
`the operator may not be able to stop, steer, or control
`undesirable movement of the machine.
`It is desirable for the planer operator to raise the planing
`cylinder above the top of such an obstruction, pass the
`planing cylinder over the obstruction and then return the
`planing cylinder to milling the pavement at the depth
`previously used. Generally, this function is manually per(cid:173)
`formed by the planer operator. However, once the planing 60
`cylinder passes over the obstruction and begins milling the
`pavement, often the milling is at a different depth than
`before the obstruction. This can affect the smoothness of the
`new pavement that is applied later.
`Therefore, it is desirable to have an automatic obstruction 65
`avoidance control system that will return the planing cylin(cid:173)
`der to milling the same depth of pavement after the obstruc-
`
`In one aspect of the present invention an obstruction
`avoidance control system for cold planer is disclosed. The
`planer has a vertically adjustable chassis supported at a
`desired elevation above a roadway by a plurality of extend(cid:173)
`able and retractable support members. Further, the planer
`has a rotatable planing cylinder, an operator control console,
`15 at least one sensor, a controller and at least one valve. The
`operator control console provides obstruction avoidance
`command signals to the controller. The at least one sensor is
`mounted to the chassis and provides at elevational signals
`representative of the elevational difference between the
`20 grade of the roadway and the planning cylinder. The con(cid:173)
`troller receives the obstruction avoidance command signals
`and elevational signals, determines vertical adjustments to
`the elevation of the chassis in response to the obstruction
`avoidance command signals and a comparison of the eleva-
`25 tional signals with a set point value, and produces at output
`signals representative of vertical adjustments to the eleva(cid:173)
`tion of the chassis and the speed of adjustment. The valve is
`in fluid communication with at least one of the plurality of
`extendable support members, receives the output signals and
`30 responsively extends or retracts the members.
`In another aspect of the present invention a method for
`controlling a cold planer in response to an obstruction is
`disclosed. The method includes providing obstruction avoid(cid:173)
`ance command signals to the controller, providing at least
`35 one elevational signal representative of the elevational dif(cid:173)
`ference of the grade of the roadway relative to the planning
`cylinder, storing an elevation set point value in a memory,
`determining vertical adjustments to the elevation of the
`chassis in response to the obstruction avoidance command
`40 signals and a comparison of the at least one elevational
`signal with the set point value, producing at output signals
`representative of vertical adjustments to the elevation of the
`chassis, and responsively extending or retracting the extend(cid:173)
`able support members.
`These and other aspects and advantages of the present
`invention will become apparent upon reading the detailed
`description in connection with the drawings and appended
`claims.
`
`45
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`For a better understanding of the invention, reference may
`be made to the accompanying drawings, in which:
`FIG. 1 is a schematic diagram showing elements of a
`55 preferred embodiment of the obstruction avoidance system
`of the present invention;
`FIG. 2 is a flowchart of software logic for the jump feature
`implemented in a preferred embodiment of the present
`invention; and
`FIGS. 3a-g are a flowchart of software logic for the return
`to grade feature implemented in a preferred embodiment of
`the present invention.
`
`BEST MODE FOR CARRYING OUT THE
`INVENTION
`A jump/return to grade control system 10 for a cold planer
`is shown schematically in FIG. 1. The cold planer has a
`
`Page 11 of 16
`
`

`

`6,152,648
`
`3
`vertically adjustable chassis 12 supported at a desired eleva(cid:173)
`tion by a plurality of extendible support members, or legs 14,
`each having a first end 16 connected to the chassis 12 and a
`second end 18 in contact with the roadway 20. The rear legs
`are generally cross-plumbed to rise and lower in tandem.
`Cold planers, also known as roadway profilers or milling
`machines, typically have a rotor, or planning cylinder 21,
`rotatably mounted on the chassis 12 at a position interme(cid:173)
`diate to forward and rearward ends of the chassis 12 and
`disposed transversely with respect to the direction of travel 10
`of the cold planner. The planning cylinder 21 has a left side
`70 and a right side 72 and a plurality of cutting bits mounted
`thereon to engage the ground or roadway 20, which is
`fragmented by the cutting action of the bits.
`The depth of the cutting action is dependent upon the
`elevational position of the planning cylinder 21 with respect 15
`to the ground 20, usually pavement of a roadway. Typically,
`the legs 14 include hydraulically actuated strut assemblies
`22 having at least one pressure chamber 24 that is connected
`to a source of pressurized hydraulic fluid which, as indicated
`in FIG. 1, is provided by a variable displacement pump 28. 20
`Flow of the hydraulic fluid is controlled by movement of a
`valve 48 in fluid communication between the variable dis(cid:173)
`placement pump 28 and the pressure chamber 24. The
`movement of the valve 48 is controlled by at least one
`solenoid 50 responsive to output control signals provided by 25
`an electronic controller 26.
`The jump/return to grade control system 10 typically
`includes an auto stop sensor 91 and a service height sensor
`93, preferably proximity sensors, for sensing the relative
`extension of the hydraulically actuated strut assemblies 22 30
`and providing a signal representative of the relative exten(cid:173)
`sion of the hydraulically actuated strut assemblies 22 to the
`controller 26. Advantageously, the service height sensor
`provides a service height signal representative of the rear
`legs being extended to a length typically allowing service to 35
`the cold planer and not typically used for milling operations,
`and the auto stop sensor provides an auto stop signal
`representative of the rear legs being extended to a length
`typically allowing for milling of the pavement by the
`planing cylinder 21.
`Further, the jump/return to grade control system 10 typi(cid:173)
`cally includes a left grade sensor 95 mounted to the chassis
`12 proximate the left side 70 and a right grade sensor 97
`mounted to the chassis 12 proximate the right side 72, which
`provide elevational signals representative of a grade refer- 45
`ence for control of the elevation of the chassis 12 and
`consequently the planing cylinder relative to the roadway
`20. The sensors are commonly calibrated after adjusting the
`legs 14 to a point where the planing cylinder 21 is just
`touching the roadway, referred to herein as a zero cut. 50
`Thereafter set points can be selected, such as one inch depth
`of cut, at which in an auto grade or auto slope mode
`controller 26 would attempt to maintain the set point dif(cid:173)
`ference between the zero cut and the current sensed value.
`Left grade sensor 95 and right grade sensor 97 could be 55
`mechanical contacting sensors, sonic sensors, laser sensors
`or any other sensor for generating signals representing the
`elevational difference between the grade of the roadway 20
`and the planning cylinder 21, or equivalent grade control
`indicators.
`Advantageously, the jump/return to grade control system
`10 includes a cross slope sensor 87, which provides a cross
`slope signal representative of the elevational difference
`along the axis of the planing cylinder. Preferably, the cross
`slope sensor 87 is centered over the planing cylinder 21 and 65
`is an inclination sensor, advantageously a capacitive fluid
`sensor.
`
`4
`The jump/return to grade control system 10 includes at
`least one operator control console 99, preferably having a
`jump/return to grade switch 98 such as a rocker switch, for
`providing a jump command signal and a return to grade
`5 command signal. However, those skilled in the art recognize
`that any other switch or combination of switches could be
`used without deviating from the scope of the invention as
`defined in the appended claims. Further, the control console
`99 may have switches for manual control (independently
`raising and lowering of each of the legs 14) of the elevation
`of the planing cylinder 21, calibrating the electronics, and
`setting cutting depths and/or slopes as well as a display for
`displaying operating parameters and conditions.
`Referring now to FIGS. 2 and 3, software logic used in
`connection with a preferred embodiment of the jump and
`return to grade functions are illustrated in flow chart form.
`The functions are subroutines called from a main control
`program able to, for example, provide automatic grade
`control using sensors 87, 95, and 97. Those skilled in the art
`can readily write software for implementing the flow charts
`using the instruction set, or other appropriate language,
`associated with particular microprocessor to be used. In a
`preferred embodiment, a Motorola 68HC11 processor com(cid:173)
`prises electronic controller 26.
`Program control for the jump routine begins in a start
`block 1201, proceeding immediately to a block 1202, where
`electronic controller 26 reads the initialization delay count
`value, maximum initialization delay value, maximum cross-
`slope value and minimum cross-slope value from memory.
`Program control then passes to block 1203.
`In block 1203, the electronic controller 26 determines
`whether the initialization delay has passed. Advantageously,
`the initialization delay is about one half of a second. If the
`controller 26 determines the initialization delay has not
`passed, the controller 26 in block 1207 sets the output
`signals to the legs to a value representing zero movement.
`Otherwise program control passes to block 1204.
`Advantageously, this function in block 1207 maintains the
`machine in the present configuration and temporarily dis-
`ables the automatic cutting depth control functions, referred
`to herein as "autohold". In one application, this function is
`useful for cutting or milling over rough or uneven pavement.
`In block 1204, the controller 26 determines whether the
`present cross slope signal value is within range. Preferably,
`the cross slope range is defined by the maximum cross slope
`value and minimum cross slope values. Advantageously, the
`maximum cross slope value is +11.31 degrees and the
`minimum cross slope value is -11.31 degrees.
`If the present cross slope signal value is not within the
`maximum and minimum cross-slope values, then program
`control passes to block 1207, to disable automatically rais(cid:173)
`ing the machine at an unsafe angle. Otherwise program
`control passes to block 1205.
`In block 1205, the controller 26 sets the output signals to
`the left leg, right leg, and rear legs to a value representative
`of a rapid raising value. From block 1205, program control
`passes to block 1206, which returns to the main control
`program.
`The logic of FIG. 2 is performed every control loop to
`help ensure proper control of the planing cylinder. However,
`those skilled in the art would recognize that the aspects of
`the control could be determined at other frequencies depend(cid:173)
`ing on factors like the speed of the machine and the density
`of the pavement.
`Turning to FIG. 3a, the software logic used in connection
`with the return to grade function proceeds from a start block
`
`40
`
`60
`
`Page 12 of 16
`
`

`

`6,152,648
`
`5
`
`5
`201 to block 202. In block 202, electronic controller 26 reads
`the return to grade disable flag, maximum cross slope value,
`and minimum cross slope value from memory 89, proceed(cid:173)
`ing to block 203.
`In block 203, the controller 26 determines whether the
`return-to-grade disable flag is in a false state. Preferably, a
`false state indicates that no predetermined conditions for
`preventing the operator from commanding the machine to
`return to milling the pavement have been met. Such condi(cid:173)
`tions could be related to operational conditions or configu- 10
`rations of the machine. If the return-to-grade disabled flag is
`in a false state, the controller 26 determines whether the
`cross slope signal is outside of the predetermined cross slope
`range. If either the disable flag is not false or the cross slope
`is out of range, program control passes to block 204, where 15
`controller 26 sets all output command signals to the legs to
`zero movement and returns to the main program in block
`205. Otherwise, program control passes to block 209, where
`controller 26 determines whether the return to grade delay
`has passed.
`Once the return to grade switch 98 becomes energized, a
`down counter begins decrementing in block 210 at each
`iteration of the return to grade logic, and stores the count
`value in a controller memory 89. Once the count value
`reaches zero, the controller 26 determines that the return to 25
`grade delay has passed and permits the front legs to begin
`lowering as discussed hereinafter. Advantageously, the
`return to grade delay is two seconds, during which only the
`rear legs are moving.
`Whether or not the counter is decremented, program 30
`control passes to block 211, where controller 26 determines
`whether the rear legs are above the auto stop position. If the
`rear legs are above the auto stop position, program control
`passes to block 212 to generate an output signal for rapidly
`lowering the rear legs and continues to block 214 in FIG. 3b.
`Otherwise, program control passes to block 213, where the
`delay counter is zeroed to permit the front legs to be
`lowered, and controller 26 generates an output signal to stop
`lowering the rear legs before proceeding to block 214 in
`FIG. 3b.
`In block 214 of FIG. 3b, program control is passed to
`block 215, to determine again whether the return to grade
`delay has passed. If not, program control passes to block
`216, where controller 26 maintains zero movement for the
`left and right front legs and proceeds to block 217 to return
`to the main program. Otherwise, program control passes to
`block 218 to begin lowering the front legs.
`In block 218, the controller 26 determines from reading
`memory 89 whether the right grade sensor 97 has been
`selected by the machine operator. If the right grade sensor 97
`has not been selected, program control passes to block 219
`in FIG. 3e. Otherwise, program control passes to block 220,
`where controller 26 determines whether the right grade
`sensor 97 is active, for example if a signal within an
`acceptable range is received from the sensor. If the right
`grade sensor is active, program control passes to 221.
`Otherwise, program control passes to block 225.
`In block 225, the controller determines from memory 89
`whether the left grade sensor 95 has been selected by the 60
`operator. If the left grade sensor 95 has been selected, the
`program control passes to block 226 in FIG. 3f. Otherwise,
`program control passes to block 227.
`In block 227, the controller sets the signal to the right leg
`to a value representing slow lowering speed and activates 65
`the left auto slope function. Preferably, the left auto slope
`function positions the left front leg in response to the
`
`6
`elevation of the right front leg, a cross slope set point stored
`in memory 89 and the cross slope signal. From block 227,
`program control passes to block 228.
`Referring back to block 221, the controller 26 reads the
`right set point from memory 89 and determines whether the
`right grade set point is a positive value. If the right grade set
`point is determined to be positive, then program control
`passes to block 222. Otherwise, program control passes to
`block 229.
`In block 222, the controller 26 determines whether the
`value of the signal from the right grade sensor 97 is above
`a right grade set point read from memory 89. If the value of
`the signal from the right grade sensor 97 is above the set
`point, program control passes to block 223 in FIG. 3c.
`Otherwise, program control passes to block 224 in FIG. 3d.
`Referring back to block 229, the controller 26 determines
`whether the value of the signal from the right grade sensor
`97 is above the set point read from memory 89. If the value
`of the signal from the right grade sensor 97 is determined to
`20 be above the set point, program control passes to block 231.
`Otherwise, program control passes to block 230.
`In 231, the controller 26 determines whether the value of
`the signal from the right grade sensor 97 is above a zero cut
`value read from memory 89. If the value of the signal from
`the right grade sensor 97 is above the zero cut value,
`program control passes to block 232. Otherwise, program
`control passes to block 233.
`Referring now to FIG. 3c, from block 223 control passes
`to block 234, where controller 26 determines whether the
`left slope control is selected by the machine operator by
`reading the left slope control state from memory 89. If left
`slope control is selected, program control passes to block
`235, where the controller 26 sets the output signal to the
`right leg to a value representing a slow lowering speed and
`activates the left auto slope function before returning to the
`main program in block 236. Otherwise, program control
`passes to block 237.
`In block 237, the controller 26 determines whether the left
`grade sensor 95 is active. If the left grade sensor 95 is not
`active, program control passes to block 238, where the
`controller 26 sets the output signals to the right and left legs
`to a value representative of a slow lowering speed before
`returning to the main program in block 239. Otherwise,
`45 program control passes to block 240.
`In block 240, the controller 26 determines whether the
`value of the signal from the left grade sensor 95 is above the
`left grade set point value stored in memory 89. If the value
`of the signal from the left grade sensor 95 is above the left
`50 grade set point value, then program control passes to block
`241, where the controller 26 sets the output signals to the
`right and left legs to a value representative of a slow
`lowering speed before returning to the main program in
`block 242. Otherwise, program control passes to block 243,
`55 where the controller 26 sets the output signal to the left leg
`to a value representative of zero movement and sets the
`output signal to the right leg to a value representative of a
`slow lowering speed, before returning to the main program
`in block 244.
`Referring now to FIG. 3d, program control passes from
`block 224 to block 245, where controller 26 determines
`whether the left slope control is selected by the machine
`operator by reading the left slope control state from memory
`89. If the left slope control is selected, then program control
`passes to block 246, where controller 26 sets the output
`signal to the right leg to a value representative of zero
`movement and activates the left auto slope function before
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`40
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`6,152,648
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`5
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`7
`returning to the main program in block 247. Otherwise,
`program control passes block 248.
`In block 248, controller 26 determines whether the left
`grade sensor 95 is active. If the left grade sensor is not
`active, program control passes to block 249, where the
`controller 26 sets the output signals to the right and left legs
`to a value representative of zero movement before returning
`to the main program in block 250. Otherwise, program
`control passes to block 251.
`In block 251, the controller 26 determines whether the 10
`value of the signal from the left grade sensor is above the left
`grade set point stored in and read from memory 89. If the
`value of the signal from the left grade sensor 95 is deter(cid:173)
`mined to be above the left grade set point, program control
`passes to block 252, where the controller 26 sets the output 15
`signals to the left leg to a value representative of a slow
`lowering speed and sets the output signals to the right leg to
`a value representative of zero movement before returning to
`the main program in block 253. Otherwise, program control
`passes to block 254, where the controller 26 sets the output 20
`signals to the right and left legs to a value representative of
`zero movement, before returning to the main program in
`block 255.
`Referring now to FIG. 3e, program control passes from
`block 219 to block 303, where controller 26 determines if
`the left grade sensor 95 is active. If the left grade sensor 95
`is not active, then program control passes to block 304,
`where controller 26 sets the output signal to the left leg to a
`value representative of a slow lowering speed and activates
`the right auto slope function before returning to the main
`program in block 305. Otherwise, program control passes to
`block 306. Preferably, the right auto slope function positions
`the right front leg in response to the elevation of the left front
`leg, the cross slope set point and the cross slope signal.
`In block 306, controller 26 determines whether the left
`grade set point read from memory 89 is positive. If the left
`grade set point is positive, program control passes to block
`307, where controller 26 sets the output signal to the left leg
`to a value representative of a slow lowering speed and 40
`activates the right auto slope function before returning to the
`main program in block 308. Otherwise, program control
`passes to block 309.
`In block 309, the controller 26 determines whether the
`value of the signal from the left grade sensor 95 is above the
`left grade set point. If the value of the signal from the left
`grade sensor 95 is not above the set point, program control
`passes to block 310, where controller 26 sets the output
`signal to the left leg to a value representative of zero
`movement and activates the right auto slope function before
`returning to the main program in block 311. Otherwise,
`program control passes to block 312.
`In 312, the controller 26 determines whether the value of
`the signal from the left grade sensor 95 is above a zero cut
`value stored in memory 89. If the value of the signal from
`the left grade sensor 95 is not above a zero cut value, then
`program control passes to block 315, where the controller 26
`sets the output signal to the left leg to a value representative
`of a slow lowering speed and activates the right auto slope
`function before returning to the main program in block 316.
`Otherwise, program control passes block 313.
`In block 313, the controller 26 determines whether the
`rear legs are above the auto stop position. If the rear legs are
`above the auto stop position, program control passes to
`block 314 where the controller 26 sets the output signal to
`the left leg to a value representative of a full lowering speed
`and calls the right auto slope function with cross-coupling
`
`8
`before returning to the main program in block 318.
`Otherwise, program control passes to block 317, where the
`controller 26 sets the output signal to the left leg to a value
`representative of a medium lowering speed and activates the
`right auto slope function with cross-coupling before return(cid:173)
`ing to the main program.
`Advantageously, cross-coupling prevents the slope con-
`trolled side from lagging behind the grade controlled side
`during the return to grade operation. Cross-coupling deter(cid:173)
`mines whether the auto slo