Leveling system for construction machine

Abstract

Leveling system for a construction machine, in particular a road construction machine or a road paver (10), with the following features: a layer thickness measuring system (110, 14) configured to measure a current layer thickness and to determine corresponding actual layer thickness values ​​for a plurality of positions, a processor (130) configured to determine, on the basis of a layer thickness profile (120), comprising a plurality of target layer thickness values ​​(Starget1, Starget2, ...) assigned to a plurality of the positions, as well as the actual layer thickness values ​​for the positions, control values ​​per position for height control of a tool of the construction machine.

Description

[0001] Embodiments of the present invention relate to a leveling system for a construction machine, in particular a road construction machine, such as a road paver or a road milling machine. Preferred embodiments relate to a leveling system with a layer thickness measuring system.

[0002] Further embodiments relate to a construction machine (road construction machine, such as a road paver or road milling machine) with a corresponding leveling system. Another embodiment relates to a device for determining a layer thickness profile. Further embodiments relate to the corresponding methods for leveling and for determining a layer thickness profile, and corresponding computer programs.

[0003] Leveling systems are used, for example, in road construction machines such as road pavers or road milling machines. The use of leveling systems, for example, in road pavers, controls the height of the paving tool (the screed) and the inclination in such a way that the paved layer is laid with the appropriate layer thickness and inclination. The leveling system levels out any unevenness in the subsoil. During the paving process, the actual height of the road paver or the paving tool (screed) relative to the subsoil or the layer already applied is scanned in order to be able to control the paving tool accordingly depending on subsoil variations. Consequently, leveling systems use a sensor mount that runs parallel to the direction of travel and extends, for example, over a length of 12 m. Such a sensor mount is available in Fig. 1a shown. Fig. 1a shows a road paver 10 with a sensor mount 12 and, in this case, four sensors 14a-d. Sensor 14b is located behind the screed 10b. The sensor mount shown with the four sensors 14a-d allows for accurate sensing and then correcting for waves in the range of 4 to 8 m. EP0542297 describes a control system for a road paver.

[0004] For correspondingly longer waves, additional height control can be carried out using a total station, as described in Fig. 1b is illustrated. Fig. 1b shows a road paver 10 with a screed 10b. The height adjustment of the screed is controlled at the traction point 10z via the traction point cylinder 10zz, as has already been done, for example, in connection with Fig. 1a In addition, or alternatively, the height of the screed 10b can also be controlled using the components 14la1 and 14la2 as well as 14t. An external reference is introduced by the total station 14t, which emits a laser beam at a predetermined height. This laser beam, emitted e.g. parallel to the ground or a reference, is then received directly by the height sensor 14la1 or indirectly after reflection by the 360° prism 14la2. This allows the actual height of the screed to be determined in relation to a fixed reference height. Due to the fixed reference height, the actual height is not subject to long-wave fluctuations, which can be determined by means of the sensor arrangement from Fig. 1 cannot be detected. Furthermore, using the total station as a virtual reference makes it possible to eliminate the need for other references, such as strings, etc. The disadvantage of using the total station is that it requires complex calibration, and one total station is often not sufficient, especially for longer streets. Therefore, there is a need for an improved approach.

[0005] The object of the present invention is to provide a leveling or, in general, a height control for construction machinery that offers a better compromise between ergonomics, accuracy and control capability for long shafts.

[0006] The object of the present invention is solved by the subject matter of the independent patent claims.

[0007] Embodiments of the present invention provide a leveling system for a construction machine, in particular a road construction machine, a road paver, or a road milling machine. The leveling system comprises a layer thickness measuring system and a processor. The layer thickness measuring system is designed to measure a layer thickness currently being applied or removed and to determine corresponding (predicted) actual layer thickness values ​​for a plurality of positions (e.g., along a direction of travel of the construction machine). In this case, for example, several current layer thickness values ​​are obtained for a plurality of positions (lined up one after the other). In other words, this plurality of layer thickness values ​​can be referred to as an actual layer thickness profile.The processor is designed to determine control values ​​for each (further) position for height control of a tool of the construction machine, e.g., the screed or the milling drum, based on a layer thickness profile (target layer thickness profile) comprising a plurality of target layer thickness values ​​assigned to the plurality of positions, as well as the (predicted) actual layer thickness values ​​for the corresponding positions.

[0008] It should be noted that, depending on the measuring system, the actual layer thickness value can be predicted based on the currently measured layer thickness, since the individual sensors in front of the screed scan the subsoil without a layer applied. The prediction is based on the measured height values ​​for each position. Without control, the predicted actual layer thickness would be generated at the corresponding positions. For example, this is negative during layer removal (road milling machine) and positive during layer application (road paver). A variation can be achieved through appropriate control based on the aforementioned target layer thickness values.

[0009] According to the exemplary embodiments, the control values ​​for each position for regulating the height of the tool are determined such that the tool is controlled in accordance with the target layer thickness profile. Furthermore, according to the exemplary embodiments, the tool is controlled by the control values ​​such that a deviation between the actual layer thickness value profile and the target layer thickness value profile, or between the actual layer thickness value and the target layer thickness value, is corrected for each corresponding position.

[0010] According to exemplary embodiments, the control values ​​for each position are selected such that, in the steady-state state of the tool, the actual layer thickness value for each position essentially corresponds to the target layer thickness value. "Essentially" means, for example, ±20%, ±10%, ±5%, ±3%, or ±1%, meaning that a maximum deviation of ±1%, ±3%, ±5%, ±10%, or ±20% (depending on the variant) is permissible. For this purpose, according to exemplary embodiments, the control values ​​are derived such that the height control of the tool takes place taking into account the control path (offset between the control position and the completed control, e.g., offset between the pivot point or virtual pivot point or the trailing edge of the screed and the pulling point) of the tool along a travel direction of the construction machine. According to exemplary embodiments, a type of correction value is determined for each position based on a deviation between the target layer thickness value and the actual layer thickness value.This correction value is applied, but due to the offset explained above, it is not applied to the current position (of the actual layer thickness value), but rather to a "future" or further position. Therefore, the height of the tool for the "future" position is determined based on the correction value and the target layer thickness value for the corresponding further position. For example, the control values ​​for each (further) position are selected such that the tool is raised and / or lowered in accordance with the target layer thickness profile upon reaching the (further) position, in order to be moved to a position corresponding to the target layer thickness value at each position. Additionally, the control values ​​for each further position can be selected such that a current deviation between an actual layer thickness value and a target layer thickness value is compensated or taken into account.

[0011] Embodiments of the present invention are therefore based on the finding that, instead of or in addition to control based on a fixed height value, control is based on varying target height values ​​in accordance with a layer thickness profile in order to compensate for long-wave unevenness. For this purpose, a target layer thickness profile is scanned based on the unevenness scanned in advance, for example, which, when applied to the unevenness, then forms a flat surface together with the unevenness. For example, a thinner target layer thickness is provided at points on a peak of unevenness than at points on the valley of unevenness. This applies in particular to road pavers or other construction machines that apply a surface. In the case of a road milling machine, or more generally the machine that removes a surface, the target layer thickness profile corresponds to the profile that is to be removed from the surface.Here, more material is removed in an uneven hill than in an uneven valley.

[0012] In both cases, the result is a surface that is flat, especially with regard to long-wave unevenness. Continuous (target / actual) comparison prevents drift. Furthermore, on-site work is reduced, as measures such as total stations, etc., are no longer required.

[0013] This means that, according to exemplary embodiments, the processor explained above is designed to derive the control values ​​from the layer thickness profile in such a way that, on an (uneven or wavy) subsurface profile, a layer to be smoothed by the tool or applied by the tool forms a flat surface along a direction of travel of the construction machine. As just explained, this is advantageously also done in the case of long-wave unevenness. At this point, it should be noted that the layer to be applied (installed) or the layer to be smoothed can have, in addition to the first dimension along the direction of travel, a second dimension transverse to the direction of travel. The control values ​​are derived from the layer thickness profile in such a way that, on the subsurface profile, a layer to be applied (installed) or smoothed by the tool forms a flat surface along a spanned plane.The plane extends along the first and the second dimension. According to embodiments, this is achieved, for example, in that the tool can be controlled in terms of its height on both the first side and the second side of the construction machine (left-right). The tool, such as the screed, extends from the first side to the second side of the construction machine or beyond the first and second sides of the construction machine and creates a flat surface. The inclination is adjusted depending on the height of the two actuators for the tool or depending on the relative height of the two actuators for the tool. The control values ​​for the two actuators are determined depending on the target inclination and the two-dimensional subsoil profile according to further embodiments.This means that, according to embodiments, the layer thickness measuring system, together with the processor, forms a first control loop for a first side (left or right of the tool). The layer thickness measuring system (or another layer thickness measuring system) and the processor form a second control loop for a second (other) side of the tool. According to further embodiments, the two control loops interact to control the tool accordingly for intermediate positions between the first and second sides of the tool, so that for intermediate positions in the steady state, the actual layer thickness essentially corresponds to the target layer thickness.

[0014] According to a simple variant, the layer thickness measuring system can be formed by two height sensors, whereby the first height sensor is arranged, for example, behind the screed and also measures the applied or leveled layer and determines a corresponding height value, while the second height sensor is arranged in front of the screed and determines a height value relative to the subsoil or the not yet leveled layer. If one starts from the simplified case of a comparable application height, the layer thickness can be determined, for example, by calculating the difference. If the application heights are not identical, offsets can be used, which then leads to very precise results, even if the distances along the direction of travel between the sensor and the pivot point are the same. With regard to the pivot point, it should be noted that this can be formed, for example, by the rear edge of the screed.By taking the theorem of radii into account, arrangements with different spacings are of course also possible. According to the exemplary embodiments, the two height sensors are permanently connected to the screed, whereby "permanently" is to be interpreted as a fixed geometric relationship between the screed and the sensors. Due to the suspension, the two sensors move together with the screed, meaning they rotate together and experience the same lifting movement (as the screed).

[0015] According to embodiments, the sensor arrangement comprises at least two or even at least three or even at least four sensors arranged on a support extending along the direction of travel of the construction machine. According to further embodiments, the layer thickness measuring system can be integrated into this sensor arrangement.

[0016] According to embodiments, the layer thickness profile is determined as a function of a subsurface profile. The subsurface profile also has a first dimension along the direction of travel and can also have a second dimension transverse to the direction of travel. According to embodiments, this subsurface profile is scanned in advance, so that a corresponding determination of the layer thickness profile with the target layer thickness values ​​for each position can also be carried out (in advance or in real time). As a result, the layer thickness profile can then have target layer thickness values ​​that vary across the positions and / or along the direction of travel.

[0017] As already mentioned above, each target layer thickness value is assigned to a position for which an actual layer thickness value can also be determined. The corresponding position is determined, for example, using a position sensor or GNSS sensor. According to exemplary embodiments, this can be coupled to the tool / screed or, alternatively, to the construction machine. The position sensor or GNSS sensor is designed to determine the positions for the actual layer thickness values, in particular positions along the direction of travel.

[0018] Further aspects of the control system are explained below. It should be noted that, depending on the exemplary embodiments, a minimum layer thickness can be specified in the layer thickness profile. This minimum layer thickness thus defines the target layer thickness value at a wave crest of the subsurface profile. The control values ​​are derived according to the specified minimum layer thickness for each position.

[0019] The approach explained above thus advantageously enables leveling of a layer thickness, e.g., a layer to be applied or a layer to be removed, which compensates for particularly long-wave unevenness. In the basic variant, this leveling requires non-conventional leveling technology of a conventional leveling system. According to further embodiments, the leveling system explained above can be combined with a conventional leveling system or integrated into a conventional leveling system. In other words, this means that the leveling system explained above can have functionalities of a conventional leveling system. This means that, according to embodiments, the processor of the leveling system explained above has a flatness controller designed to determine the control values ​​using sensor values, so that a flat surface is produced.As already explained in connection with the prior art, the evenness controller can, for example, have a plurality of distance sensors that are arranged along the direction of travel of the construction machine and measure a distance to the subsoil. It is advantageous if the layer thickness measuring system to be used, for example, uses comparable or the same distance sensors. According to exemplary embodiments, the layer thickness measuring system can be based on two distance sensors that are arranged around the pivot point of the screed, i.e. one in front of the screed and one behind the screed, and that, for example, determine the layer thickness using the difference between the two height values. Further implementations with other constellations will be explained below. According to further exemplary embodiments, the processor can have a controlled system that has, for example, a P element and / or an IT element and / or a PT element.Additionally or alternatively, the controlled system can also be controlled using a predictive model. This predictive model is particularly advantageous for the leveling approach based on layer thickness values ​​described above, since there is a temporal, or particularly a spatial, offset of several centimeters or even meters between the control time and the actual change in the applied layer thickness profile. This offset depends on parameters such as the screed bevel angle, the speed of the construction machine, the asphalt temperature, the asphalt thickness, etc. These dependencies can be taken into account using the predictive model.

[0020] Another embodiment relates to a construction machine, a road construction machine, or a road paver with a corresponding leveling system. According to further embodiments, a road milling machine or a construction machine with a milling function and a corresponding leveling system can also be created.

[0021] Further embodiments relate to a device and a calculation unit for determining the layer thickness profile (comprising the plurality of layer thickness values ​​assigned to the plurality of positions). The device comprises an interface and a calculation unit. The interface is designed to receive a subsurface profile (e.g., a scanned subsurface profile) comprising a plurality of height values ​​assigned to a plurality of positions. Furthermore, at least one target height or target depth is received via this interface or a further interface. For example, the target height can be defined by a target height value or multiple target height values ​​assigned to multiple positions. In conventional leveling systems or layer thickness measuring systems, a minimum layer thickness has been specified. This corresponds, for example, to the target height.The calculation unit is designed to determine the layer thickness profile based on a difference between the plurality of height values ​​assigned to a plurality of positions and the at least one target height or target depth or a reference by the at least one target height or target depth. According to further embodiments, the device comprises an output interface for providing or exporting the layer thickness profile to a construction machine. At this point, it should be noted again that, according to further embodiments, the target height can also be defined by a plurality of target height values ​​assigned to a plurality of positions, or the at least one target depth can be defined by a plurality of target depth values ​​assigned to a plurality of positions. This is particularly relevant when different target heights result for the left and right or along the direction of travel in order to set an inclination.According to embodiments, the plurality of target height values ​​or the one target height value define a plane or 3D planes of a layer to be smoothed or produced (installed).

[0022] According to further embodiments, a method for leveling a construction machine is provided. The method comprises the following steps: Measuring a current layer thickness to be applied or removed and determining corresponding (predicted) actual layer thickness values ​​for a plurality of positions, determining control values ​​for each position for height control of a tool of the construction machine on the basis of a layer thickness profile, comprising a plurality of target layer thickness values ​​assigned to a plurality of the positions, as well as the (predicted) actual layer thickness values ​​for the positions.

[0023] A further embodiment relates to a method for determining the layer thickness profile with the following steps: Receiving a subsurface profile comprising a plurality of elevation values ​​assigned to a plurality of the positions; receiving at least one desired elevation or depth; and determining the layer thickness profile based on a difference between the plurality of elevation values ​​assigned to a plurality of the positions and the at least one desired elevation or depth or a reference defined by the at least one desired elevation or depth.

[0024] According to further embodiments, the method can be computer-implemented.

[0025] Exemplary embodiments of the present invention are explained below with reference to the figures. They show: Fig. 1a shows a schematic representation of a construction machine with a measuring system for a leveling system; Fig. 1b shows a schematic representation of a construction machine with a leveling system; Fig. 2a shows a schematic block diagram of a leveling system according to a basic embodiment; Fig. 2b shows a schematic representation of a layer thickness measuring system according to embodiments; Figs. 2c and 2d show schematic representations of a leveling system using a layer thickness measuring system according to extended embodiments; Fig. 2e shows a schematic representation of a layer thickness measuring system according to embodiments; Figs. 3a and 3b show schematic representations of subsurface profiles and layer thickness profiles to explain embodiments; Fig. 4 shows a schematic representation of a subsurface profile in combination with a target layer thickness profile with associated parameters to explain embodiments; Fig.5a and 5b show schematic block diagrams of leveling systems according to expanded embodiments; Fig. 6a and 6b show schematic representations for explaining the control behavior of a screed as a tool of a construction machine; Fig. 7a and 7b show a schematic representation of a leveling system when used for a milling machine according to embodiments; Fig. 8a and 8b show schematic representations together with measured values ​​for explaining the compensation of long waves according to embodiments; and Fig. 9 shows a schematic block diagram for explaining the calibration process in a leveling system according to embodiments.

[0026] Before exemplary embodiments of the present invention are explained below with reference to the accompanying drawings, it should be noted that elements and structures with the same function are provided with the same reference numerals, so that the description of them is applicable to one another or interchangeable.

[0027] Embodiments of the present invention provide a leveling system. The leveling system can advantageously be used in a construction machine, in particular a road paver 10, as shown in Fig. 1a and 1b shown.

[0028] The leveling system 100 is in Fig. 2a shown schematically. The leveling system 100 comprises a layer thickness measuring system 110 and a processor 130. The layer thickness measuring system 110 is sketched here again as an example. It comprises, for example, a carrier 12, which is arranged on the screed 10b of the construction machine and carries two distance measuring devices 14a and 14b, e.g., ultrasonic sensors. The first ultrasonic sensor 14a is arranged in front of the screed as seen in the direction of travel, while the second ultrasonic sensor 14b is arranged behind the screed as seen in the direction of travel. Each of these sensors 14a and 14b determines the distance A or B from the subsoil or from the applied layer. The layer thickness can then be determined by calculating the difference between the two distances A and B. Details on this will be explained below. The determined layer thickness values ​​S1, S2, ... for the positions P1, P2, ... along the direction of travel are transferred to the processor 130.In addition, the processor 130 receives a (target) layer thickness profile 120. The layer thickness profile 120 includes target layer thickness values ​​S soll1 , S soll2 , ... for the respective positions. The layer thickness profile 120 includes, as shown here in block 120 or also in . Fig. 3a shown, differential heights plotted over the individual positions, which together with the substrate 122 form a flat layer. The substrate 122 has, as shown in Fig. 3b As shown, waves occur, here long waves ranging from 15 to 100 m. The wave troughs are marked with 122t, the wave crests with 122b. A greater layer thickness is provided in the area of ​​wave troughs 122t, while a thinner layer thickness is provided in the area of ​​wave crests 122b.

[0029] The processor 130 determines the control values ​​C1, C2, ... assigned to the individual positions such that the tool, here the screed 10b, is controlled to the corresponding height in order to move to the corresponding target values ​​S target1 , S target2 , ... the positions. The control values ​​C1, C2, ... influence the traction point adjustment and thus ultimately raise or lower the screed. The control values ​​can, for example, be concrete distance specifications by which the traction point should be adjusted. Both positive and negative control values ​​would be conceivable in this case, since the traction point can be both raised and lowered. For example, such a control value can be directly proportional to the determined difference between the target layer thicknesses and the actual layer thicknesses.According to the exemplary embodiments, a transmission ratio must be taken into account because, depending on the geometry of the screed suspension, a traction point adjustment results in x-length units (screed adjustment x, for example, between 0.1 and 10 or 0.01 and 100). Depending on the geometry, indirect proportionality can also be provided. According to a further variant, it would also be conceivable for the control values ​​to only indicate that a traction point raising or lowering is necessary. This would then be a binary control or a control with three states (-1 lowering, +1 raising and 0 no change in the traction point). This type of control value can also be combined with the control values ​​explained above, so that, for example, two or three (generally several) possible control values ​​are conceivable for lowering and raising, which indicate the degree of change. As already shown with reference to . Fig. 1b As can be seen, the height of the traction point 10z is adjusted via the traction point cylinder 10zz, but this only has an indirect influence on the height of the screed 10b or in particular the trailing edge of the screed 10bk.

[0030] Starting from the control 130 and taking into account the layer thickness profile 120, a perfect surface is theoretically formed. Since in practice the height of the tool and thus the applied layer thickness depends on further parameters besides the set height on the pull-point cylinder 10zz (current pull-point setting), the actual layer thickness S1, S2 is also taken into account for each position according to the exemplary embodiments. At this point, it should be noted that the values ​​referred to as actual layer thickness values ​​are measured, for example, relative to the substrate before the layer is applied, so that these are predicted actual layer thickness values ​​or generally height values. In this respect, the term actual layer thickness value is to be seen as synonymous with the term actual height value. As can be seen from the arrangement of the measuring system from Fig. 1a in front of the screed (cf. sensor arrangement 14a, 14c and 14d), a scan is carried out relative to the ground in front of the screed, i.e. to the position assignable to a fixed length offset starting from the screed in the direction of travel or starting from the rear edge of the screed in the direction of travel.

[0031] At this point it should be noted that according to embodiments, for example, the target value S soll1 is held at a position P1 and the layer thickness height S1 at position P1 can be compared here, wherein a control signal C 1+offset is then output. The background to this is that at the time at which the height S1 can be determined, the traction point adjustment for a further position which is offset by a control distance has already taken place. In this respect, the derived control signal C 1+offset is to be understood as a type of compensation signal, wherein the corresponding target height S soll3 is then taken into account for the further (offset) position P 1+offset (for example P3) together with the compensation signal C 1+offset.

[0032] This results in the situation where the control signal for the further position depends on the target / actual comparison of the first position P1, whereby the target height for the further position, e.g., S target3 , is also taken into account. It should be noted here that the further position, here P3, is offset from the first position P1 by an offset that can be constant, at least during operation, but is preferably assumed to be constant. This offset depends, as already explained above, on various parameters such as the speed of the construction vehicle, asphalt temperature, asphalt mixture, screed angle, etc.

[0033] The principle is applicable, for example, to road pavers with a specific layer thickness to be applied, but can also be transferred to road milling machines with a specific layer depth to be removed. For road pavers, a target layer thickness / height is determined for each position, while for road milling machines, a target layer depth / depth is determined.

[0034] This offset is once again evident from the positions of the layer thickness regulating tool 10b, the pulling point adjustment 10zz, as shown in the plan view of Fig. 2b are shown.

[0035] Fig. 2b shows a construction machine 10 with a screed 10b and a layer thickness measuring system 14r, which in this embodiment comprises a first sensor 14a and a second sensor 14b. These are attached to the screed 10b by means of a support 12 such that the first sensor 14a measures in front of the screed and the second sensor 14b measures behind the screed. The first sensor 14a measures relative to the subsoil, while the second sensor 14b measures relative to the applied layer.

[0036] In addition, according to exemplary embodiments, a further layer thickness measuring system 14l can also be provided, which is constructed analogously to the layer thickness measuring system 14r. The layer thickness measuring system 14r is located, for example, on the right side of the screed 10b, while the layer thickness measuring system 14l is arranged on the left side of the screed 10l. As already explained above, the layer thickness measuring systems 14l and 14r each measure a height relative to the subsurface. Assuming that both sensors 14a and 14b are arranged at the same mounting height, a layer thickness can be determined based on the difference between the two height values. If the screed tilts, the distances also change indirectly proportionally. With the same lever arm lengths, i.e. the horizontal distance between the sensors 14a and 14b relative to the rotation point, the layer thickness can still be determined based on the difference.In the case of lever arms of different lengths, the law of radii can be taken into account according to exemplary embodiments. Different measurement methods for determining layer thickness using distance sensors are explained, for example, in EP 2921588, EP 3048199, or EP 3228981. In addition, other methods for measuring layer thickness are also considered according to further exemplary embodiments. A particular advantage of the layer thickness measurement explained above, however, is that distance sensors can be used that are also used in conventional leveling systems.

[0037] At this point, it should be noted that the layer thickness is typically determined in the area of ​​the screed. This position is marked with reference numeral 140. According to further embodiments, a position sensor, such as a GNSS sensor, can be provided at position 140 to assign a position to the layer thickness, which improves the comparison of the target layer thickness with the actual layer thickness for each position. Furthermore, a further position sensor 142 can also be provided, for example, in the area of ​​the pulling point. As already explained above, the adjustment takes place at the pulling point for positions that will then be approached at a later time with the screed, taking the offset into account. The use of two position sensors advantageously enables the positions to be assigned to the offset between the current (screed) position and the further position (position of the pulling point adjustment).According to exemplary embodiments, only one sensor can of course be provided, and the offset can be calculated based on driving speed or the like. In addition to the layer thickness measuring system 14, according to exemplary embodiments, another sensor arrangement, here the sensor arrangement 24, can also be provided. The sensor arrangement 24 also has distance sensors that measure the distance to the ground. These sensor arrangements 24 are directly connected to the chassis of the road construction machine 10 and sense unevenness. This sensor arrangement can be provided either on one side of the construction machine or on both sides of the construction machine.

[0038] Based on the arrangement Fig. 2c The leveling system is now explained. The constellation of Fig. 2c shows the construction machine 10 with the screed 10b as well as two layer thickness measuring systems 14l and 14r for the two different sides of the screed 10b. Each side is considered separately, for example, and receives target values ​​S target via a database 150. The database 150 can, for example, be installed on the notebook 152 or be accessible via it. The notebook 152, or generally a part of the leveling system with communication means or an interface, then supplies the target data S target to the two control loops 130l and 130r. These then control the current pulling point left and right (not shown) according to the target values ​​S target for the future screed positions and the received deviations of a current screed position.

[0039] Fig. 2d shows another variant. Here, it is indicated that one of the second control loops 130l or 130r acts as the master, while the other operates as the slave. As can also be seen here, control loop 130l receives the distance values ​​from measuring device 14l, while control loop 130r receives the distance values ​​from measuring device 14r.

[0040] In this exemplary embodiment, the arrangement 14l, i.e., the measuring arrangement 14r, comprises three distance sensors 14a, 14b, and 14c. 14a is located between 14b and 14c and measures, for example, the height in the area in front of the screed or in the area of ​​the traction point 10z, while 14c measures further forward in the direction of travel toward the subsoil. The layer thickness measuring system 14l, 14r can use either the two sensors 14a and 14b with subtraction, or the sensor 14c, 14b, or alternatively, all three sensors. For example, the distance value is measured, averaged using sensors 14a and 14c, and the difference is added to the distance value of the distance sensor 14b.

[0041] The entire sensor arrangement 14 can also be expanded, for example, by using more than three sensors. This is possible, for example, in Fig. 2e shown.

[0042] Fig. 2e shows a construction machine 10 with a corresponding control circuit 130 and a sensor arrangement 14. This comprises four sensors 14a, 14b, 14c, and 14d, which are attached to a common carrier 12. The sensors shown here can be designed as so-called superski sensors, each of which has a plurality of sensor heads.

[0043] Sensors 14a and 14b together form a layer thickness measuring system 14. Sensors 14a, 14b can also be used to determine measured values ​​in the functions of a conventional leveling system (for short shafts). Additional sensors can also be advantageously used, e.g., in front of sensors 14a and 14b as seen in the direction of travel. This means that the sensor arrangement 14 (14l, 14r), in the version with two sensors 14a and 14b each, or in the version with more than two sensors 14a to 14d, can be used for both the conventional leveling system and the described leveling system for long shafts. Of course, a layer thickness can also be determined directly using sensors (14a, 14b).

[0044] According to some embodiments, the system is designed, as described above, to compensate for long-wave unevenness. According to further embodiments, short unevenness can also be compensated for, e.g., based on conventional leveling techniques.

[0045] Fig. 4 shows a layer thickness profile 120' for producing a flat surface 125 of the layer to be applied. The background profile 122, which is scanned, for example, in the preliminary run, contains elevations and depressions. For example, scanning takes place at a distance of 3 m, which can include not only the height relative to a reference but also inclination angles, etc. Based on the deviation from the reference (see Δh set ), a layer thickness profile (see "Thickness left" or "Thickness right") is then derived, separately for the two control loops. A deviation from the reference for two points can also be taken into account (Δh two ).

[0046] Referring to Fig. 5 The control loop 130 is expanded to include a flatness controller. The layer thickness control loop 130 determines the actual layer thickness S1, ... based on the actual height values ​​and compares it with the target layer thickness (see comparator 131). This control can then be carried out as above, taking into account a prediction model 137. Furthermore, according to exemplary embodiments, a flatness controller 142 can be provided. Depending on a height sensor, e.g., height sensor 14a, this controller controls the flatness in the area of ​​the traction point using a P element or a PT element.

[0047] In the screed area, the flatness is controlled using a P or PT element. This flatness control is performed without considering the prediction model 137.

[0048] Referring to Fig. 5b The model will now be explained again in detail. Fig. 5b shows the screed 10b being pulled over the pulling point 10z. The evenness is in turn adjusted using the evenness controller 142. This evenness controller 142 controls the pulling point cylinder, which behaves like an IT1 element. As a feedback loop, the height sensor value in the area of ​​the pulling point is then determined and, after optional filtering (see filter 144), fed back to the evenness controller 142. This is a control loop subordinate to the evenness control loop. The evenness control loop, as mentioned, comprises the P element and the IT1 element. Based on this, the screed, which exhibits PT2 behavior, is then controlled. This results in a height at the trailing edge of the screed, which can be determined using the sensor 14b or, in general, the sensor arrangement 14.After optional filtering using filter 146, the actual altitude value is then compared with a desired altitude value, so that a towing point adjustment can then be performed in a further control loop using the prediction model 137. The sensor arrangement 14 in conjunction with the filter 146 creates a superimposed control loop that corresponds to the control loop 130 as previously explained.

[0049] As explained above, adjusting the tension point does not result in an immediate change in the layer thickness. This is due to a so-called transient process. Fig. 6a This is shown. At a point P1, the traction point is adjusted to achieve different screed heights, as shown by curve 60. The traction point adjustment here also occurs with a certain transient. The screed follows the traction point adjustment slightly behind, which can result in a so-called "overshoot" or "undershoot," meaning that the screed dips in the other direction shortly after point P1, which is shown by curve 62. The height adjustment of screed 10b is completed at the latest at point P2, which is approximately one traction arm length away from point P1.

[0050] Furthermore, this transient response can also be viewed over time. For example, moving the traction point 10z takes half a second, in this case 0.4 s. Based on this, the layer thickness in the area of ​​the screed changes by a time factor of 0.5 s. Even though the system primarily suggests that a rotation around the screed's rear edge 10bk is taking place, it should be noted at this point that the pivot point is shifted slightly towards the traction point, as shown in the lower half of the schematic diagram. The lower half represents the kinematics of the overall system, whereby the position of the pivot point can also vary depending on the current conditions. Even when the conventional leveling control loop is activated, changes occur over the distance (time), e.g., in the range between 1 and 20 minutes.

[0051] The above principle was explained specifically in the context of road pavers (layer thickness to be applied), although the above principle can of course also be applied to other machines, such as road construction machines, that require leveling. For example, a road milling machine can be adjusted in height using this system. Fig. 7a shows the control of a road milling machine with a milling drum 10f and two height sensors 14l and 14r. These measure a certain height depending on their offset relative to the subsoil 11. When the drum 10f removes material from the subsoil 11, the measured height is reduced, as can be seen from Fig. 7b This height provides information about the removed layer and can thus be referred to as a layer thickness system. Since the subsurface profile can also be determined in advance with road milling machines, the same principle explained above can be used to determine the layer thickness to be removed in advance, which can then be kept constant using the measuring system shown, in order to remove long-wave waves in particular.

[0052] In Fig. 8a and 8bLayer thickness values ​​are shown for the individual positions 1-15. For example, the position distances are equidistant. An average desired height, in this case 5.0, is assumed. In one position, in this case position 1, the desired average layer thickness is set as the reference layer thickness and applied essentially parallel to the substrate. The individual layer thickness values ​​are determined such that a minimum layer thickness h min and a maximum layer thickness h max are not exceeded or undercut. Because layer thickness values ​​are also set in such a way that a change in layer thickness is possible without changing the substrate (cf. positions 8 and 9), the cross-slope can be adjusted.

[0053] At this point, it should be noted that a distinction is made between the control units or human-machine interfaces MM2 (manual control unit) and the global control SSI (control computer).

[0054] Fig. 9 shows a calibration process. During a start-up procedure, the height is set to the correct height level and this is defined as the reference level. Furthermore, the target points are entered into the system so that the appropriate layer thickness profile is available to the leveling system for compensating for long-wave screed irregularities and / or the desired slope.

[0055] Another embodiment relates to a method for determining the target layer thickness profile. Here, for example, as explained, the substrate profile is scanned and then determined based on the target layer thickness profile. Minimum and maximum values ​​can be taken into account.

[0056] It should be noted here that the procedure for determining and applying the target layer thickness profile is particularly applicable to subbase layers. Due to the thinness of the binder course and surface course, long-wave unevenness cannot usually be compensated for in these layers.

[0057] Although some aspects have been described in connection with a device, it should be understood that these aspects also represent a description of the corresponding method, so that a block or component of a device can also be understood as a corresponding method step or as a feature of a method step. Analogously, aspects described in connection with or as a method step also represent a description of a corresponding block, detail, or feature of a corresponding device. Some or all of the method steps may be carried out by (or using) a hardware apparatus, such as a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, some or more of the key method steps may be carried out by such an apparatus.

[0058] A signal encoded according to the invention, such as an audio signal or a video signal or a transport stream signal, may be stored on a digital storage medium or may be transmitted on a transmission medium such as a wireless transmission medium or a wired transmission medium, e.g. the Internet

[0059] The encoded audio signal according to the invention may be stored on a digital storage medium, or may be transmitted on a transmission medium, such as a wireless transmission medium or a wired transmission medium, such as the Internet.

[0060] Depending on specific implementation requirements, embodiments of the invention may be implemented in hardware or software. The implementation may be performed using a digital storage medium, such as a floppy disk, a DVD, a Blu-ray Disc, a CD, a ROM, a PROM, an EPROM, an EEPROM, or a FLASH memory, a hard disk, or other magnetic or optical storage device storing electronically readable control signals that can interact or cooperate with a programmable computer system to perform the respective method. Therefore, the digital storage medium may be computer-readable.

[0061] Some embodiments according to the invention thus comprise a data carrier having electronically readable control signals capable of interacting with a programmable computer system such that one of the methods described herein is carried out.

[0062] In general, embodiments of the present invention may be implemented as a computer program product having a program code, wherein the program code is effective to perform one of the methods when the computer program product is run on a computer.

[0063] The program code can, for example, also be stored on a machine-readable medium.

[0064] Other embodiments include the computer program for performing one of the methods described herein, wherein the computer program is stored on a machine-readable carrier.

[0065] In other words, an embodiment of the method according to the invention is thus a computer program which has a program code for carrying out one of the methods described herein when the computer program runs on a computer.

[0066] A further embodiment of the method according to the invention is thus a data carrier (or a digital storage medium or a computer-readable medium) on which the computer program for performing one of the methods described herein is recorded. The data carrier, the digital storage medium, or the computer-readable medium is typically physical and / or non-perishable or non-transient.

[0067] A further embodiment of the method according to the invention is thus a data stream or a sequence of signals that represents the computer program for carrying out one of the methods described herein. The data stream or the sequence of signals can be configured, for example, to be transferred via a data communication connection, for example, via the Internet.

[0068] A further embodiment comprises a processing device, for example a computer or a programmable logic device, which is configured or adapted to carry out one of the methods described herein.

[0069] A further embodiment comprises a computer on which the computer program for performing one of the methods described herein is installed.

[0070] A further embodiment according to the invention comprises a device or system designed to transmit a computer program for performing at least one of the methods described herein to a recipient. The transmission can be electronic or optical, for example. The recipient can be, for example, a computer, a mobile device, a storage device, or a similar device. The device or system can, for example, comprise a file server for transmitting the computer program to the recipient.

[0071] In some embodiments, a programmable logic device (e.g., a field-programmable gate array, an FPGA) may be used to perform some or all of the functionalities of the methods described herein. In some embodiments, a field-programmable gate array may interact with a microprocessor to perform any of the methods described herein. In general, in some embodiments, the methods are performed by any hardware device. This may be general-purpose hardware such as a computer processor (CPU) or method-specific hardware such as an ASIC.

[0072] The devices described herein may be implemented, for example, using a hardware apparatus, or using a computer, or using a combination of a hardware apparatus and a computer.

[0073] The devices described herein, or any components of the devices described herein, may be implemented at least partially in hardware and / or in software (computer program).

[0074] The methods described herein may be implemented, for example, using a hardware apparatus, or using a computer, or using a combination of a hardware apparatus and a computer.

[0075] The methods described herein, or any components of the methods described herein, may be implemented at least partially by hardware and / or by software.

[0076] The above-described embodiments are merely illustrative of the principles of the present invention. It is understood that modifications and variations of the arrangements and details described herein will be apparent to others skilled in the art. Therefore, it is intended that the invention be limited only by the scope of the following claims and not by the specific details presented in the description and explanation of the embodiments herein.

Claims

1. A levelling system for a construction machine, in particular a road construction machine or a road finishing machine (10) or a road milling machine, comprising: a layer thickness measurement system (110, 14) configured to measure a layer thickness currently to be applied or to be removed and respective actual layer thickness values (S1, S2, ..) for a plurality of positions (P1, P2, ..) or respective predicted actual layer thickness values (S1, S2, ..) for a plurality of positions (P1, P2, ..), a processor (130) configured to determine, based on a layer thickness profile (120) including a plurality of set layer thickness values (Sset1, Sset2, ...) allocated to the plurality of the positions, as well as the actual layer thickness values (S1, S2, ..) or predicted actual layer thickness values (S1, S2, ...) for the positions (P1, P2), control values per position (P1, P2, ..) for height regulation of a tool (10b) of the construction machine (10); wherein the layer thickness profile is determined based on a difference between the plurality of height values allocated to a plurality of the positions and the at least one set height or set depth or a reference defined by the at least one set height or set depth.

2. The leveling system according to claim 1, wherein the control values (C1, C2, ..) per position (P1, P2) are selected such that the tool (10b) is raised and / or lowered according to the layer thickness profile (120), in order to be moved per position (P1, P2) at a position according to the set layer thickness values (Sset1, Sset2, ...); and / or wherein the control values per position (P1, P2) are selected such that a determined deviation between an actual layer thickness value or predicted actual layer thickness value (S1, S2, ..) and a set layer thickness value (Sset1, Sset2, ...) is considered.

3. The leveling system according to any of the preceding claims, wherein the processor (130) is configured to determine the control value (C1, C2, ...) for the further position while considering the set layer thickness of the further position (P1+offset); and / or wherein the further position (P1+offset) is offset by an offset with respect to the respective position.

4. The leveling system according to any of the preceding claims, wherein the control values per position are selected such that in the settled state, the actual layer thickness value or the predicted actual layer thickness value (S1, S2, ..) per position essentially (±20%, ±10%, ±5%, ±3%, ±1%) corresponds to the set layer thickness value (Sset1, Sset2, ...) per position; and / or wherein the control values are derived such that the height regulation of the tool is performed by considering the regulation path (offset) of the tool (10b) along a direction of travel of the construction machine.

5. The leveling system according to any of the preceding claims, wherein the processor (130) is configured to derive the control values from the layer thickness profile (120) such that a layer to be smoothed or to be applied by the tool forms an even surface on an underground profile (122) along a direction of travel of the construction machine; and / or wherein a layer to be applied or a layer to be smoothed comprises a first dimension along the direction of travel and a second dimension transversal to the direction of travel and wherein a plane is spanned by the first dimension and the second dimension and wherein the control values are derived from the layer thickness profile (120) such that a layer to be applied (to be placed) or a layer to be smoothed by the tool comprises an even surface on an underground profile (122) along the spanned plane.

6. The leveling system according to any of the preceding claims, comprising a position sensor or GNSS sensor, in particular a position sensor or GNSS sensor coupled to the tool or coupled to the construction machine and wherein the position sensor or GNSS sensor is configured to determine the position for the actual layer thickness values or predicted actual layer thickness values (S1, S2, ..), in particular the position along the direction of travel.

7. The leveling system according to any of the preceding claims, wherein the layer thickness profile (120) comprises varying set layer thickness values (Sset1, Sset2, ...) across the positions and / or along the direction of travel and / or wherein the layer thickness profile (120) is determined in dependence on an underground profile (122).

8. The leveling system according to any of the preceding claims, wherein the processor (130) is configured to determine the control values such that a minimum layer thickness is provided per position.

9. The leveling system according to any of the preceding claims, wherein the processor (130) comprises an evenness regulator configured to determine the control values by using sensor values such that an even surface is generated; and / or wherein the processor (130) comprises a regulating path including a P component, an IT component, a PT component and / or a regulation path with a prediction model.

10. The leveling system according to any of the preceding claims, wherein the layer thickness measurement system (110, 14) forms, together with the processor (130), a first control circuit for a first side (left or right) of the tool; and / or wherein the layer thickness measurement system (110, 14) or a further layer thickness measurement system (110, 14) forms, with the processor (130), a second control circuit for a second side of the tool; or wherein the layer thickness measurement system (110, 14) forms, together with the processor (130), a first control circuit for a first side (left or right) of the tool; and / or wherein the layer thickness measurement system (110, 14) or a further layer thickness measurement system (110, 14) forms, with the processor (130), a second control circuit for a second side of the tool, wherein the first and second control circuits interact in order to control the tool accordingly for the intermediate positions between the first and second side of the tool, such that the actual layer thickness essentially corresponds to the set layer thickness for intermediate positions in the settled state.

11. The leveling system according to any of the preceding claims, wherein the layer thickness measurement system (110, 14) comprises at least one sensor (14a) in front of the screed (10b) and at least one sensor (14b) behind the screed (10b) and wherein the layer to be determined is determined by forming the difference.

12. The leveling system according to any of the preceding claims, wherein the leveling system comprises a sensor arrangement comprising at least two, at least three or at least four sensors arranged at a carrier extending along the direction of travel of the construction machine; or wherein the leveling system comprises a sensor arrangement comprising at least two, at least three or at least four sensors arranged at a carrier extending along the direction of travel of the construction machine and wherein the sensor arrangement includes the layer thickness measurement system (110, 14).

13. A construction machine (10), in particular road construction machine or road finishing machine (10) or road milling machine comprising a leveling system according to any of the preceding claims.

14. An apparatus for determining a layer thickness profile (120) including a plurality of layer thickness values (S1, S2, ...) allocated to a plurality of positions, comprising: an interface for receiving an underground profile (122) including a plurality of height values allocated to a plurality of the positions; an interface for receiving at least one set height or set depth; and a calculating unit for determining the layer thickness profile (120) based on a difference between the plurality of height values allocated to a plurality of the positions and the at least one set height or set depth or a reference defined by the at least one set height or set depth, wherein the layer thickness profile (120) comprises varying set layer thickness values (Sset1, Sset2, ...) across the positions.

15. The apparatus according to claim 14, comprising an output interface for providing / exporting the layer thickness profile (120) to a construction machine, in particular a road construction machine or a road finishing machine (10).

16. The apparatus according to claim 14 or 15, wherein the at least one set height is defined by several set height values allocated to a plurality of the positions; wherein the at least one set depth is defined by several set depth values allocated to a plurality of the positions; or wherein the at least one set height and / or the several set height values define a plane or 3D plane of a layer to be smoothed or to be produced or generated (placed).

17. A method for leveling for a construction machine, in particular a road construction machine or a road finishing machine (10) or a road milling machine, comprising: measuring a current layer thickness to be applied or to be removed and determining respective actual layer thickness values or predicted actual layer thickness values (S1, S2, ..) for a plurality of positions, determining control values per position for height regulation of a tool of the construction machine based on a layer thickness profile (120) including a plurality of set layer thickness values (Sset1, Sset2, ...) allocated to a plurality of the positions as well as the actual layer thickness values or predicted actual layer thickness values (S1, S2, ..) for the positions; wherein the layer thickness profile is determined based on a difference between the plurality of height values allocated to a plurality of the positions and the at least one set height or set depth or a reference defined by the at least one set height or set depth.

18. A method for determining a layer thickness profile (120) comprising a plurality of set layer thickness values (Sset1, Sset2, ...) allocated to a plurality of positions, comprising: receiving an underground profile (122) including a plurality of height values allocated to a plurality of the positions; receiving at least one set height or set depth; and determining the layer thickness profile (120) based on a difference between the plurality of height values allocated to a plurality of the positions and the at least one set height or set depth or a reference defined by the at least one set height or set depth; wherein the layer thickness profile (120) comprises varying set layer thickness values (Sset1, Sset2, ...) across the positions.

19. A computer program for performing the method according to claim 18, when the method runs on a computer.

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