EP3981918A1 - Road finisher and method for levelling the screed of a finisher - Google Patents

Abstract

The invention relates to a road finisher (1), comprising a screed (4) for producing a paving layer (2) on a substrate (3), on which the road finisher (1) moves in the paving direction (R) along a paving path, the screed (4) is height-adjustable and has a towing arm (5) which is attached to the road finisher (1) at a front towing point (6) formed thereon by means of a leveling cylinder (7), at least one measuring device (10) for carrying out a distance measurement, a storage device (16), a control device (17) and a regulator device (18) functionally connected thereto for adjusting a setting of the leveling cylinder (7), wherein the control device (17) is designed to depend on at least one of the base (3) and/or to a reference (11) carried out distance measurement of the measuring device (10), which is located in the installation direction (R) in front of a front edge (9) of the screed (4). measuring point (14), to calculate a correction value (K), to store this at least temporarily in the storage device (17) and, with continued paving operation, taking into account the stored correction value (K), a leveling target value (y<sub>1-target</ sub>) for the measuring point (14) by means of which the leveling cylinder (7) of the screed (4) is controlled when the front edge (9) of the screed (4) reaches the measuring point (14). The invention also relates to a method for leveling a screed (4) of a road finisher (1).

Description

The present invention relates to a road finisher according to the preamble of claim 1. The invention also relates to a method according to independent method claim 16.

In DE 196 47 150 A1 , DE 296 19 831 U1 and DE 100 25 474 B4 leveling systems for a screed of a road finisher are disclosed. These leveling systems have a towing point control loop that functions taking into account a difference between a towing arm inclination detected using an inclination sensor and a setpoint inclination value for the towing arm. The target inclination value is calculated on the basis of height monitoring carried out in the area of a trailing edge of the screed. During height monitoring, distance measurements are taken from a reference in the area of the trailing edge of the screed and compared with a target distance in order to determine the slope target value. With this device, unevenness in the subsoil that is present in front of the screed can only be taken into account imprecisely or not at all during the leveling process.

In the practice described above, the use of inclination sensors in particular has proven to be problematic, since these can react sensitively to unevenness in the subsoil and to vibrations during paving operation, which can have a negative effect on leveling control based on this. In addition, due to the fact that the tow point control takes place at the same time as the height monitoring, a high level of control and regulation effort is required for the tow point control loop described above.

DE 100 25 462 A1 discloses a road finisher with a layer thickness measuring device for determining a layer thickness of the paving layer produced in a region of a rear edge of the screed. To determine the installed layer thickness at the rear edge of the screed, a height signal from a sensor that is stationary on a screed-traction arm combination and detects a distance to the ground, as well as an inclination signal from a gradient sensor arranged on the screed-traction arm combination are used.

the DE 11 2009 001 767 T5 discloses a paver having a screed leveling controller. The controller has a first sensor located at the front of the road finisher is arranged in front of the material bunker in order to record a height to the ground. The controller also includes a second sensor that detects the height of the front tow point on the screed beam in relation to the ground.

The object of the invention is to equip a road finisher with a leveling system that reliably enables improved leveling of the paving screed of the road finisher using simple, practicable technical means and is above all suitable for producing a more precise evenness of the built-in paving layer. Furthermore, it is the object of the invention to provide a leveling method for a paving screed of a road finisher, by means of which an even paving layer can be produced more easily.

This object is achieved by a road finisher according to claim 1. This object is also achieved using a method according to claim 16.

Advantageous developments of the invention are given by the respective dependent claims.

The road finisher according to the invention comprises a paving screed for producing a paving layer on a subsoil, on which the road paver moves along a paving route in the paving direction. The screed is mounted in a height-adjustable manner and has a pulling arm which is fastened to the road finisher at a front pulling point formed thereon by means of a leveling cylinder. In addition, the road finisher according to the invention comprises a measuring device for carrying out a distance measurement, a memory device, a control device and a regulator device functionally connected thereto for adapting a setting of the leveling cylinder.

According to the invention, the control unit is designed to calculate a correction value as a function of at least one distance measurement of the measuring device to the ground and/or to a reference, which can be carried out at a measuring point in the paving direction in front of the front edge of the screed. The correction value preferably maps an unevenness detected at the measuring point as a difference between a planum and the actual subsoil with unevenness. Furthermore, the control unit is designed to store the correction value at least temporarily in the memory device and, with continued paving operation, taking into account the stored correction value, to calculate a target leveling value for the measuring point, which is used to actuate the leveling cylinder of the screed when the front edge of the screed reaches the measuring point . The controller device thus reacts to an unevenness in the subsoil detected at the measuring point at a later point in time during the paving journey, namely when the front edge of the towed screed reaches the measuring point at which the unevenness in the subsoil was directly recorded using the correction value. The determination of the correction value for detecting unevenness in the subsoil, which precedes the actual control process, is based on a simple height measurement technique that can be used excellently on the road finisher. Furthermore, the invention offers the advantage that inclination sensors can be dispensed with, as a result of which the leveling system according to the invention is designed to be more robust overall for use on construction sites. In addition, the measuring device arranged in front of the screed in the invention is less influenced by the vibrating operation of the screed, so that the distances measured by means of the measuring device can be taken into account more precisely when leveling the screed. Furthermore, the invention offers a cost-effective solution that can be easily attached to and retrofitted to the road finisher overall. Due to the fact that in the invention the control device only responds to the detected unevenness of the measuring point when the front edge of the screed reaches the measuring point, reaction times of the leveling cylinder can be better compensated, whereby a paving layer with a high degree of evenness can be produced.

The measuring device is preferably attached to the pulling arm of the screed. Movements of the towing arm, in particular raising and lowering of the towing arm, can thus be taken into account in the distance measurements. Above all, the measuring device from the towing arm on the side of the road finisher, i.e. directly next to the chassis, can precisely detect unevenness in the subsoil in front of the working area of the screed and/or measure a distance from a reference provided along the subsoil on the side of the screed, which can be used, for example, as a tensioned guide wire is available next to the road finisher. As an alternative to the guide wire, a taut cable, a curb and/or a paving layer that has already been laid could be used as a reference.

According to one variant, the measuring device can be attached to a towing vehicle of the road finisher, the measured values of which can optionally be offset against measured values from another measuring device arranged on the towing arm or on the screed in order to regulate a specific screed height.

A particularly advantageous variant provides that the measuring device is arranged in the area of the front towing point of the towing arm. This means that directly at the point of the leveling cylinder, ie a distance measurement to the ground and/or to the reference can be carried out without any notable influence of the inclination of the towing arm, on the basis of which a precise leveling of the screed is possible.

The measuring device is preferably rotatably attached to the towing arm, in particular to the front towing point of the towing arm or at least in the immediate vicinity of it. The result of this is that it maintains an equilibrium position, or at least automatically moves back into this position, independently of a change in inclination of the tension arm controlled during the leveling process. In other words, this means that the measuring device does not follow the changes in inclination of the towing arm. In this way, the height measurements of the measuring device are not influenced by changes in the inclination of the tension arm, but only detect changes in the distance from the ground and/or from the reference.

A variant provides that a linear guide is formed on the pulling arm for the measuring device, along which the measuring device can be positioned in an adjustable manner in the installation direction. This allows the distance between the measuring device and the front edge of the screed to be adjusted. The measuring device can be rotatably mounted on the linear guide in order to ignore changes in the inclination of the pulling arm.

According to one embodiment of the invention, the measuring device has at least one first sensor for measuring a distance from the reference and at least one second sensor for measuring a distance from the background. These two height measurements can be taken into account when calculating the correction value in order to record unevenness in the ground. A variant provides that the measuring device has a sensor which is designed to detect both a distance from the background and a distance from the reference. A radar sensor, for example, can be used for this.

The first and second sensors are preferably at the same distance from the front edge of the screed in the installation direction. This means that the two sensors can carry out height measurements in the installation direction at the same measuring point, on the basis of which any unevenness at the measuring point can be precisely recorded as a deviation from the subgrade. In this variant, two distance measurements are carried out at the same point in front of the screed, one to the subsoil and the other to the reference, in order to determine the correction value for this measuring point based on this.

The first and/or the second sensor are preferably in the form of an optical or acoustic sensor, for example a laser or ultrasonic sensor. The height measurements can be carried out using a transit time measurement, a phase position measurement and/or a laser triangulation.

It is conceivable that the determined correction value can be visualized as a measure for an unevenness detected in the subsoil compared to an average subsoil course (planum) on the road finisher, for example by means of a display of the screed control station. The correction factor can show small and comparatively large bumps in different colors on the display.

It is advantageous if the control device is designed to add the correction value for the measuring point based on the distance from the subsurface measured at the measuring point using the second sensor, minus the distance from the reference measured using the first sensor, and further minus a preset altitude of the reference to the subgrade determine. A correction value calculated using this equation for the measuring point by means of the control device precisely maps the unevenness that deviates there from the planum, i.e. an elevation or depression in the subsoil.

The control device is preferably configured to derive the leveling target value for the measuring point, i.e. to form the target value for a distance of the sensor from the reference, in an intermediate step to form a difference between a preset basic leveling target value and the stored correction value. The basic leveling setpoint offers a reference value for the control and regulation function, on the basis of which the screed should be towed, assuming a level, averaged subsurface, i.e. a fictitious subsurface without unevenness. The correction value is used to adapt the basic leveling target value in the practical case that the measuring device detects an unevenness in the subsoil, whereby a more precise leveling target value adapted to the unevenness can be calculated for the measuring point. The detected unevenness can thus be optimally compensated.

An advantageous development provides that the control device is configured to calculate the leveling target value from the difference between the preset basic leveling target value and the stored correction value minus a distance from the reference currently measured by the measuring device. This leveling target value is then available to the control device as an input variable, on the basis of which the leveling cylinder can be controlled for leveling the screed.

According to one embodiment, the measuring device has a plurality of sensors for measuring a distance from the background and/or from the reference, with the control device for this purpose is designed to form a respective mean value as a basis for determining the correction value based on a number of distance measurements from the background and/or from the reference that are carried out simultaneously. Because several distance measurements to the subsoil and/or to the reference are averaged to determine the correction value, a filter function comes about so that smoother transitions are possible when leveling the screed, because the controller device responds to unevenness during paving operation in a more or less dampened manner.

A development of the invention provides that the control device is configured to multiply the calculated correction value by a compensation factor dependent on the geometry of the screed. It is conceivable that in the compensation factor, in addition to or instead of the geometry of the screed, e.g. the weight of the screed and/or at least one operating parameter set and/or recorded during operation of the screed, e.g. a tamper speed and/or a heating output of the screed, is taken into account. It is also conceivable that, using the compensation factor, a density of the subsoil on which the road finisher moves during paving is taken into account. In this way, when leveling the screed, it would be possible to take into account a resilience of the subsoil, as a result of which any unevenness can already be compensated for by operating the screed. One embodiment provides that the correction factor takes into account a paving temperature of the paving layer that has been produced, which is currently measured behind the paving screed.

The road finisher preferably has at least one distance measuring device for detecting a distance covered by the front edge of the screed, it being possible to trigger the calculation of the leveling target value on the control device if the distance covered by the screed recorded by means of the distance measuring device corresponds to a distance between the measuring device and the front edge of the screed . This makes it possible for the controller to level the screed at the right time and at the right place, i.e. at the measuring point, based on the correction value calculated there, so that any unevenness measured at the measuring point can be reliably compensated for.

It is particularly advantageous if the control device is designed to continuously calculate correction values during a paving run of the road finisher along the paving route, to store these for the respective measuring points and to use the respective stored correction values to determine adjusted target leveling values. With that ensures that the controller device responds reliably to all unevenness in the subsoil along the paving route, so that an even paving layer can be produced along the entire paving route.

The control device is preferably designed to use a GPS data-based underground data model to determine the correction value. One variant provides that the GPS data-based subsurface data model can be made available to the control device by means of a web-based application, in particular using a cloud-based application, in order to supply the road finisher, in particular the control device designed on it, with updated geo-subsurface data along the paving route.

According to one embodiment of the invention, the control device is designed to calculate the correction value taking into account a piston position of the leveling cylinder that is currently set at the measuring point. The piston position can be represented, for example, by means of an extension path of the piston that can be detected, in particular using the measuring device. This would make it possible to determine unevenness in the subsoil even if the measuring device only measures the distance to the reference, for example to a tensioned guide wire, with no distance measurement to the subsoil otherwise taking place. The detection of the piston position of the leveling cylinder can thus replace the distance measurement to the ground. This can be advantageous for certain types of subsoil, especially porous subsoils.

It is conceivable that the control device is designed to continue the correction value for the measuring point based on the distance to the reference measured at the measuring point by means of the first sensor plus the height of the reference to the subgrade plus a distance of the measuring device to the height of the towing point plus a distance set based on the piston position To determine the extension path of the leveling cylinder and minus a constructive height between a chassis underside of the road finisher to the traction point of the leveling cylinder when retracted.

The present invention also relates to a method for leveling a screed of a road finisher, with a control device of the road finisher as a function of at least one distance measurement carried out with respect to the subsoil and/or a reference by means of a measuring device provided on the road finisher, with the distance measurement taking place at a front edge in the paving direction the measuring point located at the screed is carried out, a correction value is calculated and stored at least temporarily in a storage device stores and during continued paving operation, taking into account the stored correction value, calculates a leveling target value for the measuring point, based on which at least one leveling cylinder of the screed is controlled when the front edge of the screed reaches the measuring point.

In order to determine the correction value at the measuring point in front of the screed, the measuring device preferably carries out at least two distance measurements, one for the reference and one for the subsoil. This means that any unevenness in the subsoil at the measuring point can be precisely determined as a deviation from the planum and used precisely to level the screed.

The leveling system according to the invention and the leveling method according to the invention can be carried out on both sides of the road finisher. The embodiments presented above in connection with the invention can therefore be used on both sides of the road finisher.

Figur 1

einen Straßenfertiger zur Herstellung einer Einbauschicht auf einem Untergrund,

Figur 2

eine schematische, isolierte Darstellung der Einbaubohle des Straßenfertigers mit einer Messeinrichtung gemäß einer Variante der Erfindung,

Figur 3

eine schematische, isolierte Darstellung der Einbaubohle mit einer daran befestigten Messeinrichtung gemäß einer anderen Variante der Erfindung,

Figur 4

eine schematische Darstellung eines erfindungsgemäßen Regelkreises zum Durchführen der Nivellierung der Einbaubohle aus den Figuren 2 und 3,

Figur 5

eine schematische, isolierte Darstellung der Einbaubohle mit einer daran befestigten Messeinrichtung gemäß einer weiteren Variante der Erfindung, und

Figur 6

eine schematische Darstellung eines Regelkreises zum Nivellieren der Einbaubohle gemäß der Variante aus Figur 5.

Embodiments of the invention are explained in more detail with reference to the following figures. Show it:

figure 1

a road finisher for producing an installation layer on a subsoil,

figure 2

a schematic, isolated representation of the screed of the road finisher with a measuring device according to a variant of the invention,

figure 3

a schematic, isolated representation of the screed with a measuring device attached to it according to another variant of the invention,

figure 4

a schematic representation of a control circuit according to the invention for performing the leveling of the screed from the Figures 2 and 3 ,

figure 5

a schematic, isolated representation of the screed with a measuring device attached to it according to a further variant of the invention, and

figure 6

a schematic representation of a control loop for leveling the screed according to the variant figure 5 .

Identical components are provided with the same reference symbols throughout the figures.

figure 1 shows a road finisher 1 that produces a paving layer 2 on a substrate 3, on which the road finisher 1 moves along a paving direction R during a paving run. The road finisher 1 has a height-adjustable screed 4 for (pre-) compacting the paving layer 2. The screed 4 is attached to a towing arm 5, which is connected to a front traction point 6 with a leveling cylinder 7 on a tractor 22 of the road finisher 1. The pull arm 5 serves as a lever to convert a variation in a leveling cylinder position into a corresponding change in a setting angle of the screed 4 , in particular to compensate for unevenness 8 in the subsoil 3 .

figure 2 shows the screed 4, the pulling arm 5 and the leveling cylinder 7 in an isolated, schematic representation. A measuring device 10 is arranged on the pulling arm 5 between a front edge 9 of the screed and the front pulling point 6. The measuring device 10 is designed to carry out at least one distance measurement from the subsurface 3 and/or from a reference 11 . According to figure 2 the reference 11 is constructed as a guide wire, the reference 11 being at an average height h ₁₁ above the ground 3 . The reference 11 is stretched to the side of the road finisher 1 and, as will be explained in more detail below, serves to level the screed 4.

In figure 2 the measuring device 10 has a first sensor 12 for measuring a distance y ₁ to the reference and a second sensor 13 for measuring a distance y ₂ to the substrate 3 . The first and the second sensor 12, 13 are preferably positioned in the installation direction R at an equal distance x ₉ from the front edge 9 of the screed 4. Thus, at a measuring point 14 according to figure 2 two distance measurements are performed, one to measure distance y ₁ and one to measure distance y ₂ .

Furthermore shows figure 2 that the measuring device 10 can detect an unevenness 8 in the subsurface 3 at the measuring point 14 below the measuring device 10 by means of the two sensors 12, 13. The unevenness 8 represents a difference to a planum P. To compensate for the unevenness 8 from figure 2 a corresponding leveling of the screed 4 takes place when the front edge 9 of the screed 4 arrives above the unevenness 8, ie at the measuring point 14, with continued paving operation in the paving direction R. In other words, the leveling system used on the basis of the invention reacts according to the figure 2 variant shown on the detected by means of the measuring device 10 unevenness 8 at the measuring point 14 when the front edge 9 of the screed 4 in figure 2 distance x ₉ shown.

figure 3 shows a variant for the attachment of the measuring device 10 figure 2 . The arrangement off figure 3 differs from figure 2 in that the measuring device 10 is positioned directly at the front tow point 6 . At this position, so to speak at the front end of the towing arm 5, the distances y ₁ , y ₂ detected by the two sensors 12, 13 can be used particularly advantageously to compensate for unevenness 8 when leveling the screed 4 to produce an even paving layer 2. because at this point the height of the traction point 6 is recorded exactly and is not overlaid by the changes in inclination of the screed 4 .

figure 4 shows a schematic representation of a leveling system 15. The leveling system 15 can be in accordance with Figure 2 and Figure 3 use the measured height values recorded to level the screed 4 in order to compensate for unevenness 8 in the subsoil 3 .

The leveling system 15 has a memory device 16, a control device 17 and a regulator device 18 functionally connected thereto for adjusting a setting of the leveling cylinder 7. According to figure 4 the measured distances y ₁ , y ₂ of the sensors 12 , 13 are fed to the control device 17 . The control device 17 can determine a correction value K based on the measured distances y ₁ , y ₂ and taking into account the established height h ₁₁ of the reference 11 above the subgrade P.

The controller 17 off figure 4 is designed to calculate the correction value K for the measuring point 14 based on the distance y ₂ to the substrate 3 measured at the measuring point 14 using the second sensor 13 minus the distance y ₁ to the reference 11 measured using the first sensor 12 and further minus the preset height h ₁₁ of reference 11 to determine. Furthermore, the control device 17 can be configured to continuously store the correction values K determined during the paving operation along the paving section in the paving direction of travel R in the storage device 16 for the respective measuring points 14, so that the correction values K each reach the front edge 9 of the screed 4 at the corresponding Measuring points 14 can be used along the installation route for leveling the screed 4 .

Furthermore shows figure 4 that the control device 17 can display an instantaneous paving speed v _E of the road finisher 1 by means of a speed sensor 19 . The paving speed v _E transmitted to the control device 17 can be used to determine the distance x ₉ . Coupled to it or as a functionally independent unit, according to figure 4 a displacement measuring device 20 for the leveling system 15 are present in order to Distance x ₉ or a distance covered by the front edge 9 of the screed 4 to be detected when the road finisher 1 moves in the installation direction R during the paving journey.

Furthermore shows figure 4 that the control device 17 is supplied with a preset basic leveling setpoint y _1-basis . Furthermore, a compensation factor c can be stored in the control device 17, which is possibly dependent on a geometry of the screed 4.

The controller 17 off figure 4 is configured to determine, for each stored correction value K, the distance covered, ie the distance covered, that the screed 4, in particular the front edge 9 formed thereon, has covered from the time of storage. As soon as the distance covered corresponds to the distance x ₉ , the control device 17 is used to subtract the correction value K from the basic leveling target value y ₁ -basis. Optionally, the correction value K can be multiplied by the compensation factor c beforehand.

The basic leveling target value y ₁ -basis can be set manually by an operator on a control panel of the road finisher, so that a desired height of the screed 4 for the paving operation can be adjusted accordingly. The height of the screed 4 can be determined manually by the operator or measured by a layer thickness sensor, not shown.

Furthermore shows figure 4 that the desired leveling value y _{1 -Soll} determined by the control device 17 for the measuring point 14 , taking into account the correction value K, is fed to the controller device 18 . Furthermore, the control device 18 is supplied with the measured distance y ₁ . The controller device 18 is designed to calculate a controller variable u, which is supplied to an actuator 21 , based on a difference between the leveling setpoints y _{1 setpoint} calculated on the basis of unevenness 8 and the distance y ₁ currently measured at the measuring point 14 . The actuator 21, e.g. a hydraulic drive component, then defines an extension path s ₇ of the leveling cylinder 7, so that a traction point height h ₆ can be adjusted in order to position the screed 4, in particular its rear edge, at a desired height h _bo .

figure 5 basically shows the arrangement figure 3 , wherein the measuring device 10 according to figure 5 only has the first sensor 12 for measuring the distance y ₁ to the reference 11 . means of arrangement figure 5 the correction value K can be calculated primarily based on the measured distance y ₁ and based on the extension path s ₇ of the leveling cylinder 7 will. For an unevenness 8 detected by the measuring device 10, the correction value K can be calculated from a sum of the distance y ₁ , the height h ₁₁ to the reference 11, a distance h _s of the first sensor 12 to the front traction point 6 and the extension path s ₇ of the leveling cylinder 7 minus a height h _zp , with which a constructive height of a chassis underside F to the front traction point 6 when the leveling cylinder 7 is retracted, can be calculated.

figure 6 shows a schematic representation of a leveling system 15 'for the in figure 5 arrangement shown. The measured distances y ₁ and the recorded extension paths s ₇ of the leveling cylinder 7 are continuously transmitted to the control device 17, on the basis of which the correction value K is calculated and stored in the storage device 16 for each measuring point 14 along the paving route. The correction value K can be calculated using the sum described above minus the height h _zp that is present when the leveling cylinder 7 is retracted. The base leveling setpoint y _1-Soll held by the control device 17 is subtracted from the correction value K to form the leveling setpoint y _1-Soll , which is fed to the controller device 18 as an input variable at the latest when the front edge 9 of the screed 4 reaches the measuring point 14 for the measured distance y ₁ has arrived, the controller device 18 determining the controller variable u for the actuator 21 from a difference between the calculated leveling setpoint y _{1 setpoint} and the measured distance y ₁ , which adjusts the leveling cylinder 7 accordingly in order to level the screed 4 .

Claims (16)

Road finisher (1), comprising a screed (4) for producing an installation layer (2) on a substrate (3), on which the road finisher (1) moves in the installation direction (R) along a paving route, the screed (4) being height-adjustable and has a towing arm (5) which is fastened to the road finisher (1) at a front towing point (6) formed thereon by means of a leveling cylinder (7), at least one measuring device (10) for carrying out at least one distance measurement, a storage device (16) , a control device (17) and a regulator device (18) functionally connected thereto for adjusting a setting of the leveling cylinder (7), characterized in that the control device (17) is designed to, depending on at least one of the base (3) and/or to a reference (11) using the measuring device (10) carried out distance measurement at a in the direction of installation (R) in front of a front edge (9) of the screed ( 4) located measuring point (14), to calculate a correction value (K), to store this at least temporarily in the storage device (17) and, with continued paving operation, taking into account the stored correction value (K), a leveling setpoint (y ₁ setpoint) for to calculate the measuring point (14), on the basis of which the leveling cylinder (7) of the screed (4) is controlled when the front edge (9) of the screed (4) reaches the measuring point (14). Road finisher according to Claim 1, characterized in that the measuring device (10) is attached to the pulling arm (5) of the screed (4). Road finisher according to Claim 1 or 2, characterized in that the measuring device (10) is arranged in the region of the front traction point (6) of the traction arm (5). Road finisher according to one of the preceding claims, characterized in that the measuring device (10) has at least one first sensor (12) for measuring a distance (y ₁ ) to the reference (11) and at least one second sensor (13) for measuring a distance (y ₂ ) to the substrate (3). Road finisher according to Claim 4, characterized in that the first and the second sensor (12, 13) are at the same distance (x ₉ ) from the front edge (9) of the screed (4) in the installation direction (R). Road finisher according to Claim 4 or 5, characterized in that the control device (17) is designed to calculate the correction value (K) for the measuring point (14) using the distance (y ₂ ) to the subsurface (3) minus the distance (y ₁ ) measured by the first sensor (12) to the reference (11) and further subtracting a preset altitude (h ₁₁ ) of the reference (11) to the subsurface (3). Road finisher according to one of the preceding claims 4 to 6, characterized in that the control device (17) is configured to derive the leveling setpoint (y _1-soll ) for the measuring point (14) in an intermediate step, a difference from a preset base leveling setpoint (y _{1 base} ) and the stored correction value (K). Road finisher according to Claim 7, characterized in that the control device (17) is configured to calculate from the difference between the preset basic leveling target value (y _1-basis ) and the stored correction value (K) minus a distance ( y ₁ ) for reference (11) to calculate the leveling target value (y _{1 target} ). Road finisher according to one of the preceding claims, characterized in that the measuring device (10) has a plurality of sensors (12, 13) for measuring a distance (y1, y2) to the subsurface (3) and/or to the reference (11), the control device (17) is designed to calculate a respective mean value as a basis for determining the _{correction value} (K ) to build. Road finisher according to one of the preceding claims, characterized in that the control device (17) is configured to multiply the calculated correction value (K) by a compensation factor (c) dependent on the geometry of the screed (4). Road finisher according to one of the preceding claims, characterized in that the road finisher (1) has at least one path measuring device (20) for detecting a distance covered by the front edge (9) of the screed (4), the calculation of the leveling setpoint (y _1-Soll ) can be triggered by means of the control device (17) when the covered distance detected by means of the path measuring device (20). Distance of the front edge (9) of the screed (4) corresponds to a distance (x ₉ ) between the measuring device (10) and the front edge (9) of the screed (4). Road finisher according to one of the preceding claims, characterized in that the control device (17) is designed to continuously calculate correction values (K) while the road finisher (1) is paving along the paving section, to store them and to use the respective stored correction values (K) for determination of adapted leveling target values (y _{1 target} ). Road finisher according to one of the preceding claims, characterized in that the control device (17) is designed to use a GPS data-based underground data model to determine the correction value (K). Road finisher according to one of the preceding claims, characterized in that the control device (17) is designed to calculate the correction value (K) taking into account a piston position of the leveling cylinder (7) currently set at the measuring point (14). Road finisher according to one of the preceding claims, characterized in that the measuring device (10) is attached to a tractor (22) of the road finisher (1), its measured values being able to be offset against measured values from a further measuring device which is arranged on the towing arm or on the screed are to adjust a certain plank height. Method for leveling a screed (4) of a road finisher (1), wherein a control device (17) of the road finisher (1) as a function of at least one distance measurement carried out by a measuring device (10) with respect to the subsoil (3) and/or a reference (11) , wherein the distance measurement is carried out at a measuring point (14) in front of a front edge (9) of the screed (4) in the paving direction (R), a correction value (K) is calculated, this is stored at least temporarily in a storage device (16) and with continued Paving operation, taking into account the stored correction value (K), calculates a leveling target value (y _1-target ) for the measuring point (14), based on which at least one leveling cylinder (7) of the screed (4) is controlled when the front edge (9) of the screed ( 4) reaches the measuring point (14).

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