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JP2018536172

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DESCRIPTION JP2018536172
The present invention relates to the sensor and method for detecting the relative position of the
sensor relative to the guide surface 5, this sensor comprising a housing 1 and an electronic
evaluation device 7, which electronic An evaluation device outputs measured values for the
position of the guide surface 5 as a function of the measurement signal of the measuring
ultrasound transducer. The sensor comprises an ultrasound transducer array, to the outer ends
of both ultrasound transducer arrays, additionally one reference ultrasound transducer being
attached to each, and One reflector surface 12 is attached to each of the reflectors 12 in a state
of being spaced with respect to the bottom side 9 and aligned with the reference piezo disc 13,
and these reflector surfaces are respectively A reference having a known length between the two
said reference ultrasound transducers which is inclined relative to the bottom side 9 by 45 °
and directed relative to it, and accordingly A measurement zone R is formed. In the method for
relative position detection, the measured values are compensated for environmental influences
by measurements in the reference interval.
Sensor with monolithic ultrasound array
[0001]
The present invention relates to a sensor for the detection of the relative position of the sensor
relative to a guide surface, said sensor comprising a housing, flat on the bottom side of the
housing consisting of a plurality of measuring ultrasound transducers An ultrasonic transducer
array, which is longitudinally formed, is located, and the sensor outputs an electrical
measurement value for the position of the guide surface depending on the measurement signal of
the measuring ultrasonic transducer. The evaluation system of
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[0002]
For guiding of agricultural or construction and civil engineering machines, in particular guide
wires are used for so-called road finishing machines, which cause the machine to run on a preestablished route.
The guide wire is stretched parallel to the route at a precisely defined height. Through the
sensor, the relative position of the machine relative to the guide wire is detected and transferred
to the control unit of the machine, so that the control unit Remote control to follow the wire.
[0003]
In order to meet the current demands on the accuracy of machine control, in particular height
control in road construction, high resolution sensors have to be used. For this purpose,
advantageously, ultrasound sensors are taken into consideration, which are in a state capable of
generating accurate position information on the guide wire or other guide surface.
[0004]
By ultrasonic sensor or sensor is meant here all sensor units consisting of ultrasonic transducer,
electronics and sensor housing, with ultrasonic transducer electric energy to sound, and A
physical sensor element is meant, which, in turn, converts sound into electrical energy.
[0005]
Ultrasonic transducers for use in air nowadays typically consist of a circular matching layer and a
circular piezo disc, for example made of PZT (lead zirconate titanate) material.
The piezo disc is glued on the matching layer from the rear. The fine wires soldered to the piezo
disc form an electrical connection. The matching layer serves to match the acoustic wave
impedance of the piezo material to the wave impedance of air. The acoustic matching layer may,
for example, be made of hollow glass spheres which are mixed with epoxy resin. The thickness of
the matching layer is a value of λ / 4 of the desired ultrasound frequency. This type of
ultrasonic transducer produces a rotationally symmetric acoustic field. When a relatively wide
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acoustic field is required in one direction, a plurality of such ultrasound transducers are spaced
apart, arranged side by side in a narrow array, and accordingly an ultrasound array Form The
ultrasound beams formed are then superimposed clearly.
[0006]
A sensor "SONIC SKI plus" is known from Moba Mobile Automation AG, in which four separate
annular ultrasonic transducers are spaced apart. , Are arranged in a row and are incorporated in
the housing. These four ultrasonic transducers are mounted embedded in the recess in the
bottom of the housing. An additional reference measurement zone for compensating for the
temperature dependence of the ultrasound velocity and possibly other environmental influences
on the ultrasound velocity is in the first arm projecting perpendicularly from this housing , And
an opposite second arm having a reflector surface. In the housing, the central evaluation
electronics are located, which control the four ultrasonic transducers and the ultrasonic
transducers in the reference measurement zone according to the echo transit time measurement,
and ,evaluate. Because the four evaluation electronics are not located on a common matching
layer, they do not form any monolithic ultrasound array.
[0007]
This sensor is only provided for height measurement.
[0008]
This sensor is quite large in size and cumbersome with the arms projecting at right angles on the
left and right sides of the sensor and is frequently maintained in the daily operation of the road
construction work.
In the sensor housing, the individually recessed and integrated ultrasound transducers quickly
contaminate and in that case corrupt the measurement results. Cleaning of these depressions is
relatively time consuming. The time-consuming housing, which has the integration of the
individual ultrasound transducers and both projecting arms of the housing, makes this sensor
expensive in the production costs of this sensor.
[0009]
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In Patent Document 1, a control sensor is described, in which position information is calculated
using four ultrasonic sensors. These ultrasonic sensors are individually arranged at the bottom of
the housing and embedded in the synthetic material block. No mention is made as to the
configuration of the required acoustic matching layer. Only one simple temperature sensor is
provided for temperature compensation of the measurement.
[0010]
In US Pat. No. 5,956,067, a method is described for detecting the lateral position of a
construction and civil engineering machine having one sensor consisting of two ultrasound
transducers. Reference measurements are made based on the echoes reflected at the two edges
via the same transducer.
[0011]
DE 38 16 198 C1 DE-A 42 06 990 A1 DE-A 42 06 990 A1
[0012]
The object of the present invention is to disclose the sensor for detecting the relative position of
the sensor relative to the guide surface, which sensor outputs the measurement results in
horizontal and vertical directions with high accuracy. It is possible, at the same time, easy to
maintain and constructed at a low cost.
[0013]
This problem is solved by the sensor with the features of claim 1 and the features of claims 14
and 15 of the method.
Advantageous configurations of the invention are presented in the dependent claims.
[0014]
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Sound velocity depends on temperature and temperature.
With a reference measurement zone having a known length, the influence of temperature can be
compensated via a simple ratio calculation. Yet another advantage of the reference measurement
zone is that other environmental factors for the sound velocity and, correspondingly, the
accuracy of the echo transit time measurement are compensated as well.
[0015]
The sensor for the detection of the relative position of the sensor relative to the guide surface
comprises a housing, on the bottom side of which is formed a flat, elongated, consisting of a
plurality of measuring ultrasound transducers An ultrasonic transducer array is located, and the
sensor comprises an electronic evaluation device that outputs measured values for the position of
the guide surface depending on the measurement signal of the measuring ultrasonic transducer.
There is.
[0016]
In the sensor according to the invention, the reference measurement zones are additionally
provided at the outer ends of both of said ultrasound transducer arrays, one reference ultrasound
transducer in each case, One reflector surface is attached to each of the reflector surfaces in a
state of being separated from the bottom side and in a state of being aligned with the reference
ultrasonic transducer; It is realized by being inclined relative to the bottom side by the ° and
pointing in the opposite direction.
Along with this, a reference measurement zone with a known length is formed between both of
the reference ultrasound transducers.
[0017]
The 45 ° inclined reflector surface is formed as a stationary bracket above the bottom side and
is preferably directly a component of the housing. This eliminates the additional assembly of
mechanical arms or brackets.
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[0018]
In this application, the term guiding surface is used, with respect to which the relative position of
the sensor is defined. It is possible that this guide surface is the upper surface of the guide wire.
However, equally well, a guide bar or the like may be used, in which the upper edge forms a
reference value for position adjustment. However, it is likewise possible that the sensor directly
measures the distance to the ground (Boden) located below the sensor.
[0019]
According to the invention, both reference ultrasound transducers and measuring ultrasound
transducers are not discontinuous, but rather consist of an acoustically only matching layer
formed longitudinally, the back of this matching layer On the side, a plurality of measuring
piezodiscs spaced apart from one another and, additionally at the outer ends of both of the
arrangements, one reference piezodisc is attached to each. The back side of this matching layer
with the piezo disc is surrounded by the foam material. The smooth side opposite to the
matching layer on the front side is flush with the bottom side of the sensor and is the side of the
ultrasound transducer array that emits the sound waves. The ultrasound transducer array is
correspondingly formed as a monolithic unit,
[0020]
The reference measurement zone can be configured with non-continuous reference ultrasound
transducers, in which the reference piezo disk is provided with a separate matching layer to
which it belongs. In a variant of the advantageous embodiment, the reference ultrasound
transducer and the measurement ultrasound transducer are integrated together in one unit in a
monolithic ultrasound transducer array.
[0021]
Through the measuring ultrasound transducer, sound pulses are transmitted and echo signals are
received. The evaluation unit outputs measured values for the position of the guide surface in
dependence on the measurement signal.
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[0022]
In this sensor, a monolithic ultrasound transducer array is integrated at the bottom of the sensor,
flush with the consistently smooth acoustic matching layer of the ultrasound transducer array.
This flush arrangement of the matching layer on the side emitting the sound waves with the
bottom of the sensor housing provides a large, smooth flat surface that can be easily cleaned.
[0023]
The matching layer of the ultrasound transducer array, which has a thickness of λ / 4 of the
desired ultrasound frequency, is longitudinally formed. On the back side of this matching layer, at
least two, in the variant of the embodiment, five, circular measuring piezodisks are arranged
spaced apart, in a row, above the matching layer. Fixing of these measuring piezo disks is
performed, for example, by soldering, bonding or clamping.
[0024]
Experiments have shown that with rectangular piezo disks, a nearly asymmetric ultrasound beam
can be generated which results in wider in one direction. If rectangular piezo disks are arranged
on the back side of the matching layer, spaced apart side by side with the broad side of the
ultrasound beam, the number of piezo disks needed is a circular measuring piezo disk This can
be reduced relative to the required configuration. This is because these rectangular measuring
piezodiscs are then arranged approximately further apart.
[0025]
Between the piezo disks, on the rear side of the matching layer, grooves are inserted, which serve
for the acoustic-mechanical separation between the individual piezo disks. For good
electromagnetic shielding, the back side of the matching layer is additionally metallized, and a
piezo disk is then arranged on this metallisation. This arrangement is embedded in a flexible
material consisting of polyurethane foam or silicone foam for mechanical separation from the
sensor housing.
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[0026]
In a further embodiment, the matching layer of the ultrasound transducer array additionally
comprises on the back side an edge extending around the periphery, so that the flat matching
layer extends around the edge Together with the part, here form a storage tank. The storage tank
is metallized from the inside for electromagnetic shielding. A piezo disc is disposed on the bottom
of the metal-coated storage tank and is in electrical contact with the thin wire.
[0027]
A method for calculating an environmental factor on the bottom side of the sensor comprises: a
reference measurement zone; a reference ultrasound transducer of one of the reference
ultrasound transducers, a short acoustic wave having a first acoustic frequency A pulse is
transmitted, this sound wave pulse is diverted via both reflector faces and reaches the other
reference piezo disc via the reference measurement zone and is received there Do. An evaluation
device measures a first time between transmission and reception of sound pulses. Subsequently,
the same measurement is repeated in the opposite direction, and the evaluation device then
measures a second time. From the first and second measured times, an arithmetic mean value is
formed, and this reference elapsed time value Zr is the basis for the current value of the
environmental factor at the bottom of the sensor (Mass) It is used as With this double
measurement in the opposite direction, the wind effect on the reference measurement is
eliminated.
[0028]
The method for detecting the relative position of the sensor with respect to the guide surface is
performed as follows:
[0029]
First, the reference measurement described above is performed.
Subsequently, the sensor transmits, via the measuring ultrasonic transducer, in succession, an
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acoustic pulse having the second acoustic frequency, with the transmitting pulse always having
only one measuring ultrasonic transducer Only given to. Subsequently, sensors receive echo
signals at all measuring piezodiscs.
[0030]
The elapsed time values so calculated are compensated via reference values and simple ratio
calculations. That is, the distance to the wire L (mm): L = Lr x Z / Zr / 2 where Z = elapsed time
value (μs), Zr = reference elapsed time value (μs), Lr = reference length (mm)
[0031]
The reference measurement zone is operable with the same ultrasound frequency as the
measurement piezodisc. In an advantageous configuration, higher ultrasound frequencies are
selected for the reference measurement interval.
[0032]
Optionally, the distance values so calculated with the measurements carried out on each can be
handed over to a control device connected to the sensor or, however, first of all via trigonometric
calculations The exact position of the wire under the sensor is calculated, and only the X and Y
positions of the wire relative to the sensor are delivered to the controller.
[0033]
The output of the measured values takes place via electrical connections in the sensor.
If only the spacing between the sensor and the wire is to be output, this is done via a
standardized analog signal such as 0-10 V, or 4-20 mA.
[0034]
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In construction and civil engineering machines, CAN buses are extremely popular. Within one
protocol, via the CAN bus, the measured values from the individual piezo disks or, however, the X
and Y positions of the wire relative to this sensor, calculated beforehand in the sensor, It can be
transmitted.
[0035]
An indicator is advantageously associated with the housing of the sensor, which indicates
whether the guiding surface is present in a predetermined horizontal and / or vertical position
area of the sensor. . These indicators give the operator of the machine the possibility of manually
controlling the machine on the route of the machine.
[0036]
The calculated position information of the guide surface in the measurement area of the sensor is
advantageously also displayed on the indicator in the housing. Thus, likewise, the machine
operator can manually control this position information on the correct route in such a way that
the operator monitors this indicator. These indicators may be configured respectively as
numerical indication or as +/- indication for both position information.
[0037]
Embodiments of the present invention will be further described based on the figures.
[0038]
FIG. 5 is a cross-sectional view of a sensor having a measurement area.
It is a perspective view of the sensor from the lower side. It is a bottom view of a sensor. FIG. 5 is
a side view of a sensor having a connection socket. FIG. 1 is a plan view and a perspective view of
a monolithic ultrasonic transducer array. FIG. 1 is a perspective view of a monolithic ultrasound
transducer array having peripherally extending edges.
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[0039]
In FIG. 1, a cross-sectional view of the sensor is illustrated, with an ultrasound beam M forming
this sensor and a guide wire (Fuehrungsdraht) 5. The housing 1 is connected to the machine at a
predetermined position via a fixing pin 6. In the bottom side 9 of this housing 1 monolithically
composed of an alignment layer 3, a storage tank 4, a measuring piezodisc 2 and a reference
piezodisc 13. An ultrasonic transducer array is embedded flush. The measuring piezoplate 2
forms an ultrasound beam M, which detects the guide wire 5. The echoes reflected therefrom are
again received by the measuring piezodisc 2 and evaluated in the evaluation unit 7. The values
measured in the evaluation unit are transferred via the connection socket 8 to the machine. Two
reference piezo disks 13 positioned at both ends of the matching layer 3 form a reference
measurement zone R, which is used for the calculation of the influence of the temperature of the
air.
[0040]
A bottom view of the sensor is illustrated in FIGS. 2 and 3. In the bottom side 9 of the housing,
the monolithic ultrasound transducer array is coplanarly embedded with the matching layer 3 of
the ultrasound transducer array. Above the ends of the matching layer 3 one reflector bracket 11
is respectively positioned and the reflector surface 12 of these reflector brackets rotated by 45
° forms a reference measuring zone on the matching layer 3 doing.
[0041]
A fixing pin 6 is attached to the housing 1 of the sensor, which holds the sensor in place. On the
side of the housing 1 indicators 10 are provided which display optical information regarding the
position of the guide wire within the measurement area of the sensor.
[0042]
FIG. 4 shows a side view of a sensor with a fixing pin 6 attached to the housing 1 and a
connection socket 8 for the output of measured values. Above the bottom side 9 a reflector
bracket 11 can be recognized.
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[0043]
FIG. 5 shows, in a plan view and a perspective view, the matching layer 3, four rectangular
measuring piezo disks 2 for measuring the distance to the guide wire, and the first and the first
of the matching layers on the left and right of these measuring piezo disks Fig. 2 shows a
monolithic ultrasound transducer array with two circular reference piezo disks 13 each for
operation of a reference measurement zone at the two ends. The groove 15 is used to separate
the measurement piezo disk 2 and the reference piezo disk 13.
[0044]
FIG. 6 shows an ultrasound transducer array as described in FIG. 5, however additionally having
peripherally extending edges, so that the storage tank 4 is formed.
[0045]
DESCRIPTION OF SYMBOLS 1 housing 2 measurement piezo disc 3 matching layer 4 storage
tank 5 guide surface 5, guide wire 6 fixing pin 7 evaluation device 8 connection socket 9 bottom
side 10 indicator 11 reflector bracket 12 reflector surface 13 reference piezo disc 15 groove
portion M ultrasonic beam R Reference measurement interval
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