United States Patent [19J
`Sehr et al.
`
`[54] ULTRASONIC CONTROL UNIT FOR A
`TRAVELLING CUTTER
`
`[75]
`
`Inventors: Willibald Sehr, Hadamar /Steinbach;
`Martin Zarniko, Diez, both of Fed.
`Rep. of Germany
`[73] Assignee: Moba Electronic Gesellschaft fur
`Mobil-Automation mbH, Elz, Fed.
`Rep. of Germany
`[21] Appl. No.: 975,697
`[22] Filed:
`Nov. 13, 1992
`[30]
`Foreign Application Priority Data
`Nov. 15, 1991 [DE] Fed. Rep. of Germany ... 9114281[U]
`Int. CI.5 •••••.•••.•••••••••••••••••••••••••.•••••••••••• E02F 3/84
`[51]
`[52) U.S. Cl. .................................... 367 /96; 404/84.05
`[58) Field of Search .................... 367/96, 99; 181/123;
`404/84.05, 84.5; 172/4.5; 364/424.07
`References Cited
`U.S. PA TENT DOCUMENTS
`4,041,623 8/1977 Miller et al. ......................... 172/4.5
`4.473.319 9/1984 Spangler .............................. 172/4.5
`4,573,124 2/1986 Seifer ling ....................... 364/424.07
`4,722,547 2/1988 Kishi et al. .......................... 280/707
`4.924.374 5/1990 Middleton et al. ............ 364/424.07
`4,943,119 7/1990 Zarniko et al. ..................... 181/123
`
`[56)
`
`I 1111111111111111111111111111111111111111111111111111111111111111111111 IIII
`US005309407 A
`[11] Patent Number:
`[45] Date of Patent:
`
`5,309,407
`May 3, 1994
`
`4,961,173 10/1990 Sehr et al. ............................. 367/96
`5,009,546 4/1991 Domenighetti et al. ........... 404/84.5
`5,035,290 7/1991 Harms et al. ......................... 367/96
`
`FOREIGN PATENT DOCUMENTS
`3816198 9/1989 Fed. Rep. of Germany.
`2123952 2/1989 United Kingdom .
`
`Primary Examiner-Daniel T. Pihulic
`Attorney, Agent, or Firm-Ralph H. Dougherty
`
`ABSTRACT
`[57)
`Apparatus for controlling the cutting depth of a road
`grooving machine by vertical adjustment of both the
`front and rear travelling gear on the basis of a cutting
`depth control signal, which is generated by a tracer ski
`by sampling a reference plane, including at least three
`ultrasonic sensors arranged one behind the other in the
`direction of movement of the cutter, and an evaluation
`means for determining the distances between the ultra(cid:173)
`sonic sensors and a reference plane to derive therefrom
`an inclination signal as well as an averaged distance
`signal. The evaluation means controls the height of the
`two travelling gears such that the average distance of
`the cutter drum as well as the position of the machine
`relative to the reference plane are adjusted.
`
`5 Claims, 2 Drawing Sheets
`
`4
`
`----a------,------a---~
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`CATERPILLAR EXHIBIT 1037
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`Page 1 of 6
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`5,309,407
`5,309,407
`
`U.S. Patent
`
`May 3, 1994
`May3, 1994
`
`Sheet 1 of 2
`Sheet 1 of 2
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`U.S. Patent
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`Page 2 of 6
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`

`U.S. Patent
`
`May 3, 1994
`
`Sheet 2 of 2
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`5,309,407
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`Fig.2
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`Page 3 of 6
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`1
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`5,309,407
`
`ULTRASONIC CONTROL UNIT FOR A
`TRAVELLING CUTTER
`
`30
`
`The present invention relates to an ultrasonic control 5
`unit for a travelling cutter. In particular, the present
`invention deals with an improved control system for
`controlling the adjustment of the travelling gear of
`"pavement profilers" or road grooving machines.
`In known road grooving machines, which are also IO
`referred to as pavement profilers, a rotatably supported
`cutter drum is fixed in position relative to the chassis of
`the pavement profiler or road grooving machine as far
`as its axis of rotation is concerned. The pavement pro(cid:173)
`filer is provided with a front travelling gear arid a rear 15
`travelling gear. The front travelling gear is adapted to
`be manually adjusted to a fixed height value. The rear
`travelling gear is equipped with a travelling gear height
`adjustment means, which is controlled in dependence
`upon a cutting depth control signal. The cutting depth 20
`control signal is supplied by a sensor, which is attached
`to the pavement profiler and which detects the height of
`the sensor relative to a reference plane, the reference
`plane being, for example, a marginal strip of the road
`surfacing to be removed by cutting. Typically, such a 25
`sensor is defined by a "tracer ski" guided mechanically
`over the reference plane; in so doing, a potentiometer
`signal representative of the height level of the tracer ski
`can be used as a cutting depth control signal, which is
`supplied to the travelling gear height adjustment means.
`Typically, the sensor is arranged directly adjacent to
`cutter drum. In view of the fact that this is frequently
`impossible due to construction or application-depend(cid:173)
`ent limitations, the sampling, or height detection, is 35
`often carried out a short distance in front of the cutter
`drum, when seen in the direction of motion. When, due
`to the readjustment of the travelling gear height of the
`rear travelling gear, the cutter is brought to an angular
`inclined position relative to the generally horizontal 40
`reference plane, the forward displacement of the sensor
`relative to the point of application of the cutter drum
`will cause a geometry fault, which makes the depth
`control of the cutter drum work inaccurately.
`An additional problem arising in the operation of 45
`known pavement profilers or road grooving machines is
`because the reference plane frequently deviates from an
`ideal flat surface. Typically, waviness will occur in the
`course of the reference plane. This wavy reference
`plane is detected by the tracer ski in a correspondingly 50
`wavy shape so that the cutting operation will, in turn,
`result in a wavy pattern.
`U.S. Pat. No. 4,961,173 discloses an ultrasonic con(cid:173)
`trol unit for a travelling construction machine provided
`with a plurality of ultrasonic sensors, which are ar- 55
`ranged in closely spaced, juxtaposed relationship and by
`means of which a guide rope can be sampled for effect(cid:173)
`ing e.g. lateral guidance or height guidance of a road
`grooving machine.
`It is the principal object of the present invention to 60
`provide an ultrasonic control unit for a travelling cut(cid:173)
`ter, which permits a more accurate adjustment of the
`desired cutting depth.
`A preferred embodiment of the ultrasonic control
`unit according to the present invention will be more 65
`readily understandable with reference to the following
`detailed description and the appended drawings, in
`which:
`
`2
`FIG. 1 is a schematic side view of a road grooving
`machine provided with one embodiment of the ultra(cid:173)
`sonic control unit according to the present invention;
`and
`FIG. 2 is a block diagram of the ultrasonic control
`unit according to the present invention.
`As can be seen in FIG. 1, the road grooving machine
`1, has a cutter drum 2, which is rotatably supported on
`the road grooving machine, as well as front and rear
`travelling gears 3, 4. The front travelling gear 3 as well
`as the rear travelling gear 4 are secured to the road
`grooving machine 1 with the aid of travelling gear
`height adjustment means (not shown). For the purpose
`of automatically adjusting the height of the rear travel(cid:173)
`ling gear, such a travelling gear height adjustment
`means, which is typically constructed as an electro(cid:173)
`hydraulic adjustment means, is known per se. In the
`present invention, such a travelling gear height adjust(cid:173)
`ment means can also be used for the front travelling
`gear 3 so that a detailed description of the structural
`design of the travelling gear height adjustment means is
`not necessary here.
`In accordance with the present invention, the ultra(cid:173)
`sonic control unit comprises at least three ultrasonic
`sensors 10, 11, 12, which are arranged one behind the
`other essentially in the direction of movement of the
`road grooving machine 1 in such a way that a reference
`plane can be sampled by their sound cones. The refer(cid:173)
`ence plane to be sampled is normally a marginal strip of
`a road whose surfacing has to be removed by cutting
`down to a predetermined depth. The ultrasonic sensors
`10, 11, 12 are, in any case, spaced apart to such an extent
`that their sound cones will not overlap one another at
`the location of the reference surface to be sampled.
`In the preferred embodiment of the present invention
`of the type shown in FIG. l, the ultrasonic control unit
`only comprises the three ultrasonic sensors 10, 11, 12
`which are shown in the figure and which are attached
`to the road grooving machine 1 on the same level and at
`identical distances a from one another. The advantages
`of this type of arrangement of the ultrasonic sensors will
`be evident to the person skilled in the art from the de(cid:173)
`scription of signal processing following below.
`The block diagram of the ultrasonic control unit is
`shown in FIG. 2. The ultrasonic sensors 10, 11, 12 as
`well as, optionally, additional ultrasonic sensors 13, 14
`are connected to a computing unit 21 via adequate
`transmitting and receiving circuits 16, 17, 18 as well as,
`optionally, circuits 19, 20, the computing unit 21 defin(cid:173)
`ing together with the transmitting and receiving circuits
`an evaluation means 15. The computing unit 21 pro(cid:173)
`vides at its outputs 22, 23 control signals for the travel(cid:173)
`ling gear height adjustment means for effecting a verti(cid:173)
`cal adjustment of the travelling gears 3, 4.
`An analog-to-digital converter 24 is positioned be(cid:173)
`tween the input 25 for a nominal cutting depth signal
`and the computing unit 21.
`The computing unit causes the ultrasonic sensors 10
`to 12 (and, optionally, 13, 14) to be activated cyclically
`for a sequential transmission of ultrasonic pulses, the
`transit time from the respective transmission of an ultra(cid:173)
`sonic pulse to the reception of the echo reflected by the
`reference plane being measured by the same ultrasonic
`sensor which transmitted the pulse. On the basis of this
`transit time, the computing unit 21 will determine the
`distance sl, s2, s3 between each ultrasonic sensor 10, 11,
`12 and the reference surface. Then the evaluation means
`examines whether each of the distances measured can
`
`Page 4 of 6
`
`

`

`5,309,407
`
`3
`be acknowledged as a valid measurement, or whether it
`must be rejected as faulty measurement.
`A distance will be rejected as faulty measurement if
`the measuring point in question lies more than a prede(cid:173)
`termined distance outside of the plane which is deter- 5
`mined by the measuring points associated with the other
`distances.
`In the preferred embodiment, where three ultrasonic
`sensors 10, 11, 12 are attached to the road grooving
`machine 1 on one level and at identical distances from 10
`one another, the detection of faulty measurements can
`be carried out by simply forming a difference. In this
`case, the computing unit 21 forms the differences dl2,
`dl3, d23 between two distances sl and s2, or sl and s3,
`or s2 and s3 in each case. The distances which are classi- 15
`fied as valid distances are those whose difference is
`smaller than a predetermined limit value representing
`the admissible waviness of the reference plane. If, for
`example, one of the three sensors detects an obstacle,
`e.g., in the form of a stone, lying on the reference plane, 20
`the distance in question (which is assumed to be the
`distance s3 in the present case) will be shorter than the
`other two distances sl, s2 by the height of this obstacle.
`In this instance, the difference d12 will essentially be
`equal to zero and, consequently, it will be smaller than 25
`a predetermined limit value, whereas the differences
`d13 and d23 exceed the limit value. Hence the evalua(cid:173)
`tion means will reject the third distance s3 as faulty
`measurement. Subsequently, the average distance dm
`will be calculated in accordance with the following 30
`relationship average value of the distances classified as
`valid distances:
`
`4
`which is supported for rotation relative to said road
`grooving machine (1), and front and rear travelling
`gears (3, 4), one (4) of said travelling gears being pro-
`vided with a first travelling gear height adjustment
`means controlled in dependence upon a cutting depth
`control signal, characterized in that:
`the other traveling gear (3) is provided with a second
`travelling gear height adjustment means;
`at least three ultrasonic sensors (10, 11, 12) are ar(cid:173)
`ranged on the road grooving machine (1). one be(cid:173)
`hind the other essentially in the direction of motion
`of said road grooving machine (1);
`an evaluation means (15) is provided for detecting the
`distances (sl, s2, s3) between the ultrasonic sensors
`(10, 11, 12) and a reference surface on the basis of
`ultrasonic sensor signals of said ultrasonic sensors
`(10, 11, 12);
`that the evaluation means (15) being adapted to de(cid:173)
`rive from said measured distances (sl, s2, s3), on
`the one hand, an inclination signal representing the
`angle of inclination of the cutter (1) relative to the
`reference surface and, on the other hand, an aver(cid:173)
`aged distance signal (dm); and
`the evaluation means (15) being further adapted to
`derive control signals for the two travelling gear
`height adjustment means from said· averaged dis(cid:173)
`tance signal (dm), from the inclination angle, and
`from a nominal cutting depth which can be ad(cid:173)
`justed.
`2. An ultrasonic control unit according to claim 1,
`characterized in that, for readjusting the cutting depth,
`both travelling gear height adjustment means are acted
`upon by codirectional control signals, which depend on
`35 said averaged distance signal (dm).
`3. An ultrasonic control unit according to claim 1,
`characterized in that, for readjusting the angle of incli(cid:173)
`nation of the road grooving machine O relative to the
`reference surface, both travelling gear height adjust-
`40 ment means are acted upon by contradirectional control
`signals, which are derived from the inclination signal.
`4. An ultrasonic control unit according to claim 1,
`characterized in that the evaluation means (15) will
`reject one of the measured distances (sl, s2, s3) as faulty
`45 measurement. if the measuring point in question lies
`more than a predetermined distance outside of the plane
`which is determined by the measuring points associated
`with the other distances; and
`the evaluation means (15) will calculate the averaged
`distance signal by averaging only on the basis of
`the distances (sl, s2, s3) which have not been re(cid:173)
`jected as faulty measurements.
`5. An ultrasonic control unit according to claim 1,
`characterized in that the ultrasonic sensors (10, 11, 12)
`55 are attached to the road grooving machine (1) on a
`respective known level and at known distances (a) from
`one another;
`the evaluation means (15) determines the differences
`(dl2, dl3, d23) between two distances (sl, s2; sl, s3;
`s2, s3) in each case,
`the evaluation means (15) classifies the distances (sl,
`s2) whose difference (d12) is smaller than a limit
`value as valid distances; and
`the evaluation means (15) calculates the average dis(cid:173)
`tance (dm) as an average value of the distances (sl,
`s2) classified as valid distances.
`* * * * *
`
`dm=(sl +s2) / 2
`
`As soon as the obstacle is no longer within the detection
`range of the third ultrasonic sensor 12, all the differ(cid:173)
`ences d12, d13, d23 will be smaller than the limit value.
`Now, the evaluation means. Will not reject any of the
`distances as faulty measurement. Hence, the average
`value will be calculated in accordance with the follow(cid:173)
`ing formula:
`
`dm=(sl +s2+s3) / 3
`
`On the basis of the given nominal value or rather the
`nominal cutting depth, the average distance dm to the
`reference Plane and the inclination of the cutter (in the
`direction of motion) relative to the reference plane, the
`evaluation unit forms the control signals for the vertical 50
`adjustment of the front as well as of the rear travelling
`gear height adjustment means so that the height and the
`parallelism of the cutter are adjusted.
`The invented ultrasonic control unit for a travelling
`cutter avoids cutting depth faults caused by an undesir(cid:173)
`able angle of inclination of the travelling cutter relative
`to the reference plane, it compensates substantially for
`the waviness of the reference plane, and it facilitates the
`work of the operator of the road grooving machine by
`holding the road grooving machine in a parallel posi- 60
`tion. Obstacles on the reference plane are recognized by
`the invented ultrasonic control unit by detection of the
`respective faulty measurements so that such obstacles
`will not impair the accuracy of cutting depth adjust(cid:173)
`ment.
`What is claimed is:
`1. An ultrasonic control unit for a travelling road
`grooving machine (1) comprising a cutter drum (2),
`
`65
`
`Page 5 of 6
`
`

`

`UNITED STA TES PA TENT AND TRADEMARK OFFICE
`CERTIFICATE OF CORRECTION
`
`PATENT NO.
`
`DATED
`
`INVENTOR(S) :
`
`5,309,407
`May 3, 1994
`Sehr et al.
`
`It is certified that error appears in the above-indentified patent and that said Letters Patent is hereby
`corrected as shown below:
`
`Column 3, line 39, change "the evaluation means. Will not reject"
`to -- the evaluation means Will not reject.
`
`In the Claims:
`
`Claim 3, line 3 (column 4, line 38), change"()" to -- (1)
`
`Signed and Sealed this
`
`Twenty-seventh Day of October, 1998
`
`Attest:
`
`Attesting Officer
`
`Commissioner of Parents and Tradnnar/.:.s
`
`BRUCE LEHMAN
`
`Page 6 of 6
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`