United States Patent [19J
`Hohmann, Jr.
`
`I 1111111111111111 11111 111111111111111 IIIII IIIII IIIII IIIII lll111111111111111
`US005556226A
`[Ill Patent Number:
`[45] Date of Patent:
`
`5,556,226
`Sep. 17, 1996
`
`[54] AUTOMATED, LASER ALIGNED LEVELING
`APPARATUS
`
`[75]
`
`Inventor: Howard E. Hohmann, Jr., Saxonburg,
`Pa.
`
`[73] Assignee: Garceveur Corporation, Louisville,
`Ky.
`
`[21] Appl. No.: 391,200
`
`[22] Filed:
`
`Feb. 21, 1995
`
`Int. Cl.6
`..................................................... E0lC 23/07
`[51]
`[52] U.S. Cl . ......................... 404/84.1; 404/84.5; 404/101
`[58] Field of Search ............................ 404/72, 75, 84.05,
`404/84.5, 84.1, 84.2, 101, 103, 110, 114,
`118
`
`[56]
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`4,655,633
`4,930,935
`5,078,215
`
`4/1987 Somero et al ............................ 404/75
`6/1990 Quenzi et al ............................. 404/75
`1/1992 Nau .......................................... 172/4.5
`
`5,107,932
`4/1992 Zachman et al. ........................ 172/4.5
`7/1992 Nomura et al. ...................... 404/84.05
`5,129,803
`Primary Examiner-David J. Bagnell
`Assistant Examiner-Pamela A. O'Connor
`Attorney, Agent, or Firm-John E. Vanderburgh
`[57]
`ABSTRACT
`
`The laser alignment system of apparatus for leveling flow(cid:173)
`able material, in which two radiant energy beam detectors
`mounted on opposite ends of an elongated leveling member
`are responsive to a projected radiant energy beam establish(cid:173)
`ing a leveling plane, is modified for operation when one of
`the detectors is blocked from receiving the projected radiant
`energy bean by an obstruction such as a support column,
`equipment or personnel. Whereas each detector signal is
`normally used to generate a separate adjustment signal for
`an adjustment device such as an hydraulic cylinder to raise
`or lower the associated end of the elongated leveling mem(cid:173)
`ber, when one detector is blocked from receiving the radiant
`energy beam the detector elevation signal generated by the
`other, unblocked, detector is used to generate the adjustment
`signals for both ends of the elongated leveling member.
`
`10 Claims, 3 Drawing Sheets
`
`68
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`59
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`57
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`
`Page 1 of 9
`
`CATERPILLAR EXHIBIT 1045
`CATERPILLAR v. WIRTGEN
`IPR2018-01091
`
`

`

`U.S. Patent
`
`Sep. 17, 1996
`
`Sheet 1 of 3
`
`5,556,226
`FIG.1
`PRIOR ART
`
`53
`
`59
`
`~11
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`65
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`
`49
`
`81
`
`101
`
`21
`89
`
`Page 2 of 9
`
`

`

`U.S. Patent
`
`Sep. 17, 1996
`
`Sheet 2 of 3
`
`5,556,226
`
`r------------------------------7
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`
`49
`
`Page 3 of 9
`
`

`

`U.S. Patent
`
`Sep. 17, 1996
`
`Sheet 3 of 3
`
`START
`
`111
`
`5,556,226
`FIG.4
`
`113
`
`CHECK LEFT
`SIDE UP AND
`DOWN SIGNALS
`
`N
`
`115
`
`123
`
`ARE
`SIGNALS
`PRESENT
`y
`RESET TIMER
`TURN RIGHT
`OFF
`
`125
`
`CHECK RIGHT
`SIDE UP AND
`DOWN SIGNALS
`
`127
`
`135
`
`N
`
`ARE
`SIGNALS
`PRESENT
`y
`RESET TIMER
`TURN TRANSFER
`OFF
`
`117
`INCREMENT
`LEFT SIDE
`WATCHDOG
`TIMER
`
`121
`
`119
`IS TIMER N
`TIMED OUT
`y
`TRANSFER RIGHT
`SIDE CONTROL TO
`LEFT SOLENOIDS
`
`129
`INCREMENT
`RIGHT SIDE
`WATCHDOG
`TIMER
`
`133
`
`131
`IS TIMER N
`TIMED OUT
`y
`TRANSFER LEFT
`SIDE CONTROL TO
`RIGHT SOLENOIDS
`
`137
`
`139
`
`141
`
`RETURN TO START
`
`SILENCE BUZZER
`AND TURN OFF
`LIGHT
`
`143
`
`Page 4 of 9
`
`

`

`5,556,226
`
`1
`AUTOMATED, LASER ALIGNED LEVELING
`APPARATUS
`
`BACKGROUND OF THE INVENTION
`
`5
`
`1. Field of the Invention
`This invention relates to apparatus for leveling flowable
`materials such as concrete, asphalt, dirt and gravel in which
`an elongated leveling member is maintained in alignment
`with a desired leveling plane by a laser alignment system. In
`particular, it relates to an improvement in such a system
`having a pair of laser beam detectors on opposite ends of the
`elongated leveling member so that the system can maintain
`leveling accuracy when one of the detectors is temporarily
`blocked from receiving the laser bean such as by a support
`column, a truck, personnel or other obstruction.
`2. Background Information
`The invention has particular application to concrete
`screeds, but has application to other apparatus for leveling 20
`flowable materials such as, for instance, graders.
`The concrete screed is a device used when pouring and
`leveling (i.e., screeding) large concrete floors, such as used
`in large warehouse buildings, department stores and other
`large area construction projects as well as large outdoor
`concrete areas. Examples of concrete screeds are provided in
`U.S. Pat. Nos. 4,655,633 and 4,930,935. These machines
`consist of a self propelled, rotating turret supporting a large
`telescoping or extendable boom, which can typically extend
`20 feet from the turret. At the end of the boom is a self
`adjusting screed head, typically about 13 feet wide, which
`can automatically maintain a level position regardless of the
`machine's position. During the pouring of a large concrete
`floor, trucks deliver the concrete and discharge it on the
`ground. The screed head is positioned at the head of the
`freshly discharged concrete at exactly the desired horizontal
`height. The screed head is then smoothly pulled toward the
`turret by the boom, thereby evenly leveling and consolidat(cid:173)
`ing the concrete at exactly the desired horizontal height. The
`screed head is then repositioned to an adjacent location
`where fresh concrete has been placed by a truck. Again, the
`screed head is retracted toward the turret creating another
`section of smooth, (screeded) concrete.
`One of the important features of these prior art concrete
`screeds is that they produce an extremely flat, level concrete
`floor in a short time-period. Each of the individually
`screeded sections matches the height of the adjacent sections
`with precision. In order to accomplish this, an automatic
`laser alignment system is provided. A laser projector is first
`installed outside the perimeter of the area to be poured. The
`laser projector generates a beam which is swept in a hori(cid:173)
`zontal plane to provide an extremely fiat leveling plane,
`normally several feet above the ground. Sensors responsive
`to the laser beam are located on posts at both ends of the
`moveable screed head. These sensors monitor the beam
`location relative to the end posts and therefore can transmit
`electrical signals indicating how much the leveling plane is
`above or below the desired location on the end posts.
`Vertical actuators, such as hydraulic cylinders, are provided
`for both ends of the screed head. These vertical actuators
`allow each end of the screed head to be vertically moved so
`that the respective ends are kept within a very small toler(cid:173)
`ance of a desired vertical position as the screed head pulls
`the concrete toward the turret. A controller provides auto(cid:173)
`matic control of the screed end positions, and therefore,
`screed height and levelness, during the pulling of the con(cid:173)
`crete. For example, if the controller detects that the laser
`
`45
`
`2
`beam is moving down on a screed end sensor it provides
`signals to the actuator (such as to solenoid valves for the
`hydraulic cylinder) for that end to move the screed end down
`until the beam is centered again on the sensor. As the screed
`is moved from position to position, the screed head always
`reestablishes and maintains the correct vertical location of
`both ends by means of the laser alignment system.
`The commercial embodiment of the concrete screed
`described in the above patents is known as the LASER
`(trademark Somero Enterprises, Inc.). The
`10 SCREED
`LASER SCREED incorporates a feature which provides
`frequent control corrections for the screed end height. The
`self-propelled frame has stabilizer legs by which it can be
`tilted so that the boom retracts along an upward 2% grade
`15 (i.e., the boom is angled upwards from its free end to the
`turret). As the boom end is pulled toward the turret, it is
`gradually rising in elevation. However, the laser sensors on
`the screed head ends are rapidly and continually sensing the
`height of the screed end posts. When the screed end post
`height increases by the very small margins permitted by the
`machine (i.e., Vs" increase), the laser sensors send a signal
`to the central processing unit to adjust the screed end post
`height back down to the desired elevation. In this manner,
`each side of the screed head is independently and automati-
`25 cally controlled to stay within a very narrow elevation
`tolerance band. This provides for a practically seamless
`control of concrete height between adjacent sections that are
`pulled, plus providing a very flat, level surface within the
`pulled section. The operator merely has to command the
`30 screed boom to be retracted and the concrete is automati(cid:173)
`cally screeded to the correct height, blending with a height
`of adjacent concrete sections.
`While the laser screed works very well, there is one
`problem which has remained unsolved during the eight (8)
`35 years since the introduction of the LASER SCREED. The
`laser sensors can only function if they have an unobstructed
`view of an alignment source. If the laser beam is broken by
`an object, such as a building vertical support column, then
`the sensor will not provide a signal to the controller, and the
`40 affected screed end will not automatically adjust its height.
`Unfortunately, most building sites have a dozen or even
`several dozen, vertical support columns which are in place
`when the concrete floor is poured. As the screed is moved
`around the floor, pulling the numerous section of concrete,
`the vertical support columns frequently block the laser beam
`from hitting the sensors during part of each pull. This
`interference is called "column block" and it disrupts the
`automatic operation of the laser screed. Without a control
`signal, the controller unit does not know how to adjust the
`50 screed end. Therefore, an instrument light is provided to
`inform the operator that there is column block on the
`affected sensor. The operator must immediately assume
`manual height control of the affected screed end when the
`column block light is illuminated. The boom continues to
`55 pull toward the turret at its set speed. Because of the 2%
`upward grade established for the boom, the height of the
`screed end must somehow be adjusted to prevent the screed
`end from also rising at the 2% grade and therefore ruining
`the floor flatness. The operator must manually control the
`60 screed end height and estimate the correct height corrections
`as the boom is retracted until the sensor moves into a
`position where it is unblocked. At this point, the automatic
`system becomes active again. Unless the manual corrections
`were made reasonably accurately, the screed end is abruptly
`65 moved to its correct height. This corrective movement can
`cause an unwanted wave or disruption in the floor surface.
`It should be noted that while the boom is retracting, the
`
`Page 5 of 9
`
`

`

`5,556,226
`
`3
`operator is often rotating the turret fight or left in response
`to obstacles (such as the vertical columns) and is checking
`around the machine to make sure that none of the numerous
`personnel or their equipment are getting too close to the
`machine. It is therefore very undesirable to also require the 5
`operator to continually monitor whether column block
`exists. In spite of these unwanted characteristics, there has
`been no solution to the problem of "column block" up to this
`point. It has also been found that in some jobs, "column
`block" is more frequently caused by the trucks delivering the
`concrete and other equipment rather than the vertical col(cid:173)
`umns. Thus, this provides even more incentive to find a
`solution to the problem.
`There is a need, therefore, for an improved laser aligned
`apparatus for leveling flowable materials, and in particular
`for concrete screeds.
`There is a specific need for such improved apparatus
`which can maintain floor levelness when one of the sensors
`becomes blinded by an obstruction.
`There is an additional need for such improved apparatus 20
`which responds automatically to blinding of one of the laser
`detectors.
`
`10
`
`15
`
`4
`when read in conjunction with the accompanying drawings
`in which:
`FIG. 1 is a partially schematic side elevation view of
`leveling apparatus of prior art design.
`FIG. 2 is a schematic laser leveling control system for the
`apparatus of FIG. 1.
`FIG. 3 is a schematic diagram illustrating in more detail
`a portion of the control system of FIG. 2.
`FIG. 4 is a logic flow chart for the control system of FIG.
`
`2.
`
`FIG. 5 is a schematic diagram of an alternate control
`system in accordance with the invention.
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENT
`
`SUMMARY OF THE INVENTION
`
`These needs and others are satisfied by the invention
`which is directed to apparatus for leveling flowable material
`having a control device which, when one radiant energy
`beam sensor is blocked by an obstruction from receiving the
`projected beam of radiant energy and therefore does not
`generate a signal indicating an elevation deviation, sends the
`detector signal from the unblocked sensor to the adjustment
`mechanisms at both ends of the elongated leveling member
`until the blocked sensor clears the obstruction and again
`begins to generate elevation deviation signals.
`In one embodiment of the invention, switching control
`means is inserted between the controller which generates the
`adjustment signals, such as for solenoid valves for hydraulic
`actuators adjusting the elevation of the ends of the elongated
`leveling member, and the solenoid valves. In this embodi(cid:173)
`ment, the switching control means, which includes a pro(cid:173)
`cessor such as a programmable logic controller (PLC), has 40
`a timer which repetitively times an interval longer than the
`duration between adjustment signals when the elongated
`leveling device is moved along a boom included at a
`predetermined angle to
`the projected leveling plane.
`Absence of an adjustment signal during this interval is an 45
`indication that the associated detector is blinded, and ini(cid:173)
`tiates application of the adjustment signal from
`the
`unblinded side to the solenoid valves on both sides. When an
`adjustment signal is again received from the detector that
`was blinded, indicating that it has cleared the obstruction, 50
`the respective adjustment signals are sent to the associated
`adjustment mechanisms (i.e., solenoid valves).
`In another embodiment of the invention, the intelligent
`switch is placed between the sensors and the controllers
`which generate the adjustment signals. As the sensors con(cid:173)
`tinuously send signals to the controllers which indicate the
`position of the sensor relative to the projected leveling plane,
`the switching means can immediately detect that a sensor
`has been blocked from receiving the radiant energy beam,
`such as by an obstruction. Thus, the switching means 60
`immediately applies the signal from the unblocked sensor to
`both inputs to the controller means for generating both
`adjustment signals.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`A full understanding of the invention can be gained from
`the following description of the preferred embodiments
`
`The invention will be described as applied to a laser
`aligned concrete screed; however, it will be realized by those
`skilled in the art that the invention is application to other
`apparatus for leveling flowable materials such as for
`instance graders.
`The concrete screed 1 is of the type disclosed in U.S. Pat.
`No. 4,655,633, and in particular that described in U.S. Pat.
`25 No. 4,920,935, both of which are hereby incorporated by
`reference. The concrete screed 1 includes a self-propelled
`frame 3 mounted on steerable wheels 5. Mounted on the
`frame 3 is a rotatable turret 7 which supports a cantilevered,
`telescoping boom 9. Mounted on the free end of the boom
`30 9 is a screed assembly 11, the details of which can be
`understood by reference to U.S. Pat. No. 4,930,935. The
`frame 9, has front and rear stabilizer legs 10a and 10b which
`can be separately adjusted to position the boom 9 at an
`anglearelative to the horizontal using a level gauge (not
`35 shown). Preferably, the anglea is set to establish about a 2%
`upward grade for the boom.
`The screed assembly 11 includes a horizontal support
`member 13 secured at its center to the end of the boom 9. An
`elongated leveling member in the form of screed 15 having
`a longitudinal axis 16 is suspended at one end 17 from the
`horizontal support 13 by a screed elevation tube 19 and at
`the other end 21 by the elevation tube 23. The elevation
`tubes 19 and 23 respectively form part of elevation adjust(cid:173)
`ment mechanisms 25 and 27.
`The elevation adjustment mechanism 25 includes a guide
`tube 29 secured to the one end 17 of the horizontal support
`13 and in which the elevation tube 19 is vertically slidable.
`A double acting hydraulic cylinder 31 is mounted at its lower
`end to the guide tube or horizontal support 13 and has its
`actuator rod 33 connected to the upper end of the elevation
`tube 19 so that operation of the hydraulic actuator 31 raises
`and lowers the elevation tube 19, and therefore, adjusts the
`elevation of the end 17 of the screed 15 relative to the
`55 horizontal support 13. Similarly, the elevation adjustment
`mechanism 27 includes the guide tube 35 in which the
`elevation tube 23 is vertically positioned by the hydraulic
`actuator 37 having its actuator rod 39 connected to the upper
`end of the elevation tube 23.
`The hydraulic actuators 31 and 37 are operated by sole-
`noid valves 41 and 43, respectively, which control the flow
`of hydraulic fluid provided by a pump 45 through hydraulic
`lines 47. The solenoid valves 41 and 43 are controlled by
`adjustment signals provided by a laser alignment system 49.
`65 The alignment system 49 includes a pair of spaced apart
`laser beam detectors 51 and 53 supported by masts or posts
`55 and 57 mounted on top of the elevation tubes 19 and 23
`
`Page 6 of 9
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`

`

`5,556,226
`
`10
`
`5
`at the first and second ends 17 and 21, respectively, of the
`screed assembly 11. These laser beam detectors 51 and 53
`may be, for instance, of the type sold under Model No. R2S
`or R2N by Spectra-Physics Laserplane, Inc. Construction
`and Agricultural Division of Dayton, Ohio. These receivers 5
`are 360° OMNI-directional receivers which detect the posi(cid:173)
`tion of a projected leveling plane 59 generated by a laser
`beam from a laser beacon projector 61. The projector can be
`of the type sold under model numbers ELl,1044-L or 945
`also by Spectra-Physics Construction and Agricultural Divi-
`sion of Dayton, Ohio. The laser projector 61 is positioned off
`to the side of the area where concrete is to be screeded. The
`laser beam detectors 51 and 53 generate a pair of signals
`which provide an indication of the elevation of the respec(cid:173)
`tive detectors relative to the projected leveling plane 59. The
`two signals generated by the laser detector 51 are transmit- 15
`ted over leads 63 and 65 to a controller unit 67. This
`controller may be of the type sold under Model No. CB20T0
`also by Spectra-Physics. The detector 51 generates a steady
`high level logic signal on the lead 63 if the detector 51 is low
`relative to the projected leveling plane 59. Under these 20
`conditions a pulse signal is routed on the lead 65. If the
`detector 51 is high relative to the projected leveling plane 59
`a steady high logic level signal is generated on the lead 65
`and the pulse signal is present on the lead 63. When the
`elevation of the detector 51 is in alignment with the eleva- 25
`tion of the projected leveling plane 59, a steady high level
`logic signal is generated on both leads 63 and 65. If the
`detector 51 does not detect the reference laser beam, as when
`the beam is blocked by an obstruction such as the support
`column 68, the pulse signal is generated on both leads 63 and 30
`65.
`The controller unit 67 generates first adjustment signals
`on the leads 69 and 71 in response to the signals received on
`the leads 63 and 65. In the systems of U.S. Pat. Nos.
`4,655,633 and 4,930,935, these adjustment signals were
`applied directly to tile solenoid valve 41 to raise or lower the
`first end 17 of the laser screed to bring the detector 51 into
`alignment with the projected leveling plane 59. The laser
`detector 53 generates similar signals on leads 73 and 75
`which are utilized by the controller unit 77 to generate
`second adjustment signals on the leads 79 and 81 for
`operation of the solenoid valve 43.
`The controller units 67 and 77 are each provided with
`three indicator lights: a center green light 83 indicating that
`the respective detector 51 or 53 is vertically aligned with the 45
`projected leveling plane 59; an upper orange light 85 indi(cid:173)
`cating that the detector is above the projected leveling plane
`59; and a second lower orange light 87 indicating that the
`detector is below the projected leveling plane. Under normal
`circumstances, the system automatically maintains both 50
`ends of the screed 15 at proper elevation relative to the
`projected leveling plane 59, and the lights provide the
`operator with an indication that the automatic system is
`accomplishing this task. However, when one of the detectors
`becomes blocked from receiving the projected laser beams 55
`such as by the column 68, a track or other equipment, or
`even a worker, the automatic system can no longer adjust the
`elevation of the end of the screed assembly 11 having the
`blocked detector. According to the present state of the art,
`the operator must take over and operate a hand control 89 to 60
`provide inputs to the blocked side. As discussed above, this
`is not completely satisfactory, as the operator does not have
`precise information on the elevation of the affected end of
`the screed. This can cause unevenness in the floor, especially
`at the point where the detector becomes unblocked and 65
`makes what may be a gross correction to bring the associated
`end of the screed back into proper alignment.
`
`6
`As was discussed above, the boom 9 on which the screed
`assembly 11 is carried, is supposed at an angle a which
`produces about a 2% upward grade relative to the horizontal,
`and therefore, to the project leveling plane 59. Thus, as the
`screed assembly 11 is pulled toward the frame 3, the screed
`15 rises. This requires periodic adjustment downward of the
`elevation tubes 19 and 23 to maintain a level floor. Thus, first
`and second adjustment signals are regularly generated by the
`controller units 67 and 77. In accordance with the embodi(cid:173)
`ment of the invention illustrated in FIG. 2, a switching
`control 91 is interposed in the lines 69, 71, and 79, 81
`between the controller units 67 and 77 and the solenoid
`valves 41 and 43. The switching control 91 monitors the
`adjustment signals generated by the controller units 67 and
`77. With the screed assembly 11 being translated by the
`boom 9 at a constant rate, the adjustment signals should be
`generated at specified intervals as the screed assembly is
`raised by the angled boom 9. If the switching unit 91 does
`not detect the adjustment signals from a controller unit 67 or
`77 for this specified interva 1, it determines that the associ(cid:173)
`ated detector 51 or 53 is blocked. Under these conditions, the
`switching control 91 switches the adjustment signals from
`the controller unit associated with the unblocked detector to
`the solenoid valve associated with the block detector so that
`both of the solenoid valves then receive the adjustment
`signal generated from the unblocked detector.
`When the switching control 91 again detects adjustment
`signals from the controller unit associated with the formally
`blocked detector, indicating that that detector is now seeing
`the laser bean, the respective adjustment signals are again
`directed to the associated solenoid valves. Thus, in the
`example shown in FIG. 2, where the detector 51 becomes
`blocked by the column 68 so that adjustment signals are no
`longer generated on the leads 69 and 71 by the controller
`35 unit 67, the switching control 91 applies the adjusnnent
`signals generated on the leads 79 and 81 by the other
`controller unit 77 to the solenoid valve 41 over the leads 93
`and 95, as well as, sending those signals over to leads 97 and
`99 to the associated solenoid valve 43. If the switching
`40 controller 91 detects that both of the detectors are blocked it
`sounds an audible alarm 101 and blinks a light 103 to
`indicate this condition to the operator. Obviously, manual
`control must be applied until at least one detector becomes
`unblocked.
`FIG. 3 is a schematic diagram of the switching control 91.
`The switching control 91 includes 2 two-pole, double throw,
`relay switches 105 and 107. Operation of the relays is
`controlled by a processor in the form of a programmable
`logic controller (PLC) 109. The PLC 109 monitors the
`signals on the leads 69, 71, 79 and 81, and when it detects
`the absence of adjustment signals on one of the pairs of these
`leads, it energizes the coil of the appropriate relay 105 or 107
`to transfer the signals on the other pair of lines to the affected
`lines. The switches 105 and 107 are shown in their normal,
`unenergized states which prevails when both of the laser
`detectors are receiving the laser beam. Under these condi(cid:173)
`tions, the signals on leads 69 and 71 are applied to the leads
`93 and 95 for operation of the solenoid valve 41, while the
`leads 79 and 81 are connected to the leads 97 and 99 for
`providing adjustment signals to the solenoid 43. When, for
`instance, the detector 51 becomes blocked so that the
`adjustment signals are not being generated on the leads 69
`and 71, the PLC 109 activates a driver which energizes the
`coil R1 of the relay 105, so that the adjustment signals on the
`leads 79 and 81 are applied to the leads 93 and 95, as well
`as to the leads 97 and 99. The coil R2 of the relay 107 is
`energized when the detector 53 is blocked so that the
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`adjustment signals on a leads 69 and 71 are applied to the
`leads 97 and 99 for energizing the solenoid valve 43.
`FIG. 4 is a flow chart 111 of the logic implemented by the
`PLC 109 for the embodiment of the invention illustrated in
`FIGS. 2 and 3. The PLC 109 first checks the left side (e.g. 5
`controller 67) for an indication of an up or down signal as
`indicated at 113. If no signals are present at 115, a left side
`timer is incremented at 117. If the timer is tinned out,
`indicating the absence of adjustment signals from the left
`side for longer than would be expected, thus indicating that 10
`the left side detector is blocked as determined at 119, the
`relay such as relay 105 is operated at 121 to provide the right
`side adjustment signals to the left solenoid. If a left side
`signal is present at 115, the left side timer is reset at 123.
`The routine 111 then checks for right side up and down 15
`adjustment signals at 125. If no such signals are present, as
`determined at 127, a right side timer is incremented at 129.
`If this timer has timed out, indicating that the fight side
`detector (e.g. 53) is blocked, as determined at 131, left side
`control is provided to the right solenoid at 133. Again, if the 20
`right side signals are present when checked at 127 the right
`side timer is reset at 135.
`Next, if the left transfer is on at 137, meaning that the
`relay 105 is energized, and the right side transfer is on,
`meaning that the relay 107 is also energized at the same time 25
`as indicated at 139, the buzzer 101 and the light 103 are
`energized at 141 to alert the operator to the fact that
`adjustment signals for neither side are being generated. This
`could indicate that both detectors are blocked, that the
`projector is not generating the projected leveling plane, or 30
`perhaps that the boom has stopped moving. If either of the
`relays 105 or 107 is not energized the horn is silenced and
`the light is turned off at 143. The logic 111 is implemented
`by a timer interrupt repetitively at a rate such as five times
`per second.
`FIG. 5 illustrates a second embodiment of the invention
`wherein the switching control 91 is interposed between the
`detectors 51 and 53 and the controller units 67 and 77. Thus,
`the switching control 91 receives the continuous signals
`generated by the detectors. As it will be recalled, the detector
`51, for instance, generates a steady high level logic signal on
`one or both of the leads 63 and 65 when it is seeing the laser
`beam. If the detector does not see the laser beam, a pulse
`signal is generated on both of the leads 63 and 65. Thus, the
`switching control 91 can immediately detect when the
`detector has been blocked. In this case, the switch control 91
`applies the continuous detector signals from the unblocked
`detector to both of the controller units 67 and 77 over the
`leads 145, 147 and 149, 151. Thus, the controller unit 67 or
`77 associated with the blinded detector would generate
`adjustment signals utilizing the detector signals from the
`unblinded detector.
`For the embodiment of the invention shown in FIG. 5, the
`PLC 109 can use the same logic as shown in the flow chart 55
`of FIG. 4. In this instance, however, the timers could be set
`for a shorter interval the time interval in this ansient as soon
`as the PLC 109 detected a blocked detector.
`The present invention provides a marked improvement in
`the operation of laser aligned apparatus for leveling flowable 60
`materials. By automatically providing adjustment signals to
`the solenoids associated with a blinded detector, a much
`smoother floor is produced. As the end of the elongated
`leveling member will be properly g an adjustment signal
`generated for the other end of the elongated leveling mem- 65
`ber is a very reasonable assumption of the signal that would
`have been available if the detector had not become blocked.
`
`40
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`35
`
`45
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`50
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`8
`Thus, the adjustment that is needed when the blinded
`detector again picks up the project laser beam is very minor
`and does not appreciably affect the levelness of the floor.
`While specific embodiments of the invention have been
`described in detail, it will be appreciated by those skilled in
`the art that various modifications and alternatives to those
`details could be developed in light of the overall teachings
`of the disclosure. Accordingly, the particular arrangements
`disclosed are meant to be illustrative only and not limiting
`as to the scope of invention which is to be given the full
`breadth of the claims appended and any and all equivalents
`thereof.
`What is claimed is:
`1. Apparatus for leveling a flowable material relative to a
`projected leveling plane established by a radiant energy
`beam in a location having obstructions which block said
`radiant energy beam from portions of said projected leveling
`plane, said apparatus comprising:
`elongated leveling means having a longitudinal axis, a
`first end and a second end:
`support means for supporting and moving said elon(cid:173)
`gated leveling means generally transversely to said
`longitudinal axis, to level said flowable material, said
`support means including first elevation adjustment
`means for adjusting elevation of said first end of said
`elongated leveling means in response to a first
`adjustment signal, and a second elevation adjustment
`means for adjusting elevation of said second end of
`said elongated leveling means in response to a sec(cid:173)
`ond adjustment signal; and
`radiant energy beam alignment means comprising:
`first and second spaced apar