Abstract
A method for monitoring the compaction process of an asphalt layer to be compacted in road construction is provided comprising the steps: detecting the edges limiting the hot asphalt layer transversely to the road pathway by means of a temperature sensor arranged on a road roller compacting the asphalt layer, and dividing the detected asphalt layer into at least two width segments across the road pathway, wherein the position of the road roller on the asphalt layer transversely to the road pathway is determined from the measurement of the temperature sensor and is assigned to one of the width segments, the working operation of the road roller on the width segment is quantified via an operating parameter and stored, and the quantified working operation for each width segment is displayed to the operator for at least one past working interval. A road roller for carrying out the method is also provided.
Claims
1. A method for monitoring a compaction process of an asphalt layer to be compacted in road construction, comprising the steps: a) detecting edges limiting a hot asphalt layer transversely to a road pathway via a temperature sensor arranged on a road roller compacting the asphalt layer; and b) dividing the detected asphalt layer into at least two width segments across the road pathway; wherein c) a position of the road roller on the asphalt layer transversely to the road pathway is determined from a measurement of the temperature sensor and the position of the road roller is assigned to one of the width segments; d) a working operation of the road roller on the width segment is quantified by an operating parameter and stored; and e) the quantified working operation for each width segment is displayed for at least one past working interval.
2. The method according to claim 1, wherein the detecting of the edges limiting the hot asphalt layer transversely to the road pathway occurs periodically and successively via the temperature sensor, or in that the temperature sensor detects both edges simultaneously.
3. The method according to claim 1, wherein at least one of the following parameters is used as the operating parameter: a time period; a number of passages; a number of reversing operations; a traveled distance; a substrate stiffness; and/or a vibration intensity of a roller drum of the road roller.
4. The method according to claim 1, wherein boundaries of the past working interval are defined using the same operating parameter as the one used for the quantification of the working operation and/or another parameter.
5. The method according to claim 1, wherein the parameter or parameters used for the quantification of the working operation is/are stored during the working interval, and wherein data antecedent to the working interval is replaced by newly recorded data during the working operation.
6. The method according to claim 1, wherein the detected asphalt layer is divided into at least the three width segments left side, middle and right side across the road pathway.
7. The method according to claim 1, wherein the width segments across the road pathway are equal in size.
8. The method according to claim 6, wherein the width segments located at the edges of the detected asphalt layer have a smaller width across the road pathway than the width segments located in the middle of the detected asphalt layer.
9. The method according to claim 1, wherein when determining the position of the road roller on the asphalt layer from the measurement of the temperature sensor, a measuring angle of the temperature sensor and/or a traveling direction and/or a steering angle and/or a steering mode, e.g. a crab-steering mode, of the road roller is/are taken into account.
10. A road roller for compacting an asphalt layer in road construction, comprising: a machine frame; a drive engine; a driver's cab; at least one roller drum and/or a wheel; a temperature sensor; and a control unit; wherein the control unit is configured to carry out the method according to claim 1.
11. The road roller according to claim 10, wherein the control unit comprises a rolling memory which stores the quantified working operation for each width segment within the past working interval.
12. The road roller according to claim 10, wherein the temperature sensor comprises a thermal imaging camera.
13. The road roller according to claim 10, wherein the road roller comprises one of a tandem roller, a single-drum roller or a rubber-tired roller.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) The present invention will now be explained in greater detail with the help of the examples shown in the figures, which show schematically:
(2) FIG. 1 is a side view of a tandem roller;
(3) FIG. 2 is a side view of a single-drum roller;
(4) FIG. 3 is an illustration of the detection of the asphalt layer by the temperature sensor in a side view;
(5) FIG. 4 is a basic illustration for the calculation of the perspective of the temperature sensor;
(6) FIG. 5 is a rolling pattern and its registration;
(7) FIG. 6 is a possible display of the statistical evaluation;
(8) FIG. 7 is another possible display of the statistical evaluation; and
(9) FIG. 8 is a flow chart of the method.
(10) Similar components or components with similar functions are designated by identical reference numbers in the figures. Recurring components are not designated separately in each figure.
DETAILED DESCRIPTION OF THE INVENTION
(11) FIGS. 1 and 2 respectively show a road roller 1 with a driver's cab 2 and a machine frame 3. Moreover, the road rollers 1 have a drive engine 4, e.g., a diesel engine. FIG. 1 shows a tandem roller moving with its two roller drums 5 over the ground 7 to be compacted during a working operation. FIG. 2 shows a single-drum roller that has a roller drum 5 and additional wheels 6 with which the single-drum roller moves over the ground 7 to be compacted. During a working operation, the road rollers 1 frequently travel back and forth, so that they compact the ground 7 whether moving forward or backward. The forward movement is referred to as the working direction a, as indicated in the figures, even if the road rollers 1 can also work in the opposite direction, merely in order to illustrate the description.
(12) The road rollers 1 comprise a temperature sensor 8 arranged at the essentially highest point of the road rollers 1. In the embodiment shown, this is the roof of the driver's cab 2. The temperature sensors 8 are, e.g., thermal imaging cameras or infrared cameras. As indicated by the dashed arrow, the temperature sensors 8 are oriented in such a way that they capture the region ahead of the road roller 1 in the working direction a. Other arrangements and orientations of the temperature sensors 8, such as an orientation of the measured region against the working direction a, are also possible. The angle , at which the temperature sensor 8 is oriented in relation to the ground or vis--vis a plumb line, is known. The temperature sensor 8 is connected to a control unit 9, which is located, in particular, in the driver's cab 2. The control unit 9 is part of the on-board computer of the road roller 1 and is used for both the metrological as well as the statistical evaluation of the data collected by the temperature sensor 8. Moreover, the control unit 9 is connected to a display device 10, by means of which the statistical evaluation of the distribution of the quantified working operation between the width segments of the asphalt strip can be displayed to the operator of the road roller 1. Naturally, the control unit 9 can also transmit the evaluated data via a cable or wireless connection to a further terminal, e.g., a smartphone or a tablet computer, said further terminal providing for at least the display of the data to the operator. Computation steps for obtaining this display of the data from the acquired measurement results could theoretically also be performed by the terminal using, for example, a suitable app.
(13) FIGS. 3 and 4 illustrate the detection of the asphalt layer and the determination of the position of the road roller 1 transversely to the road pathway using a thermal imaging camera as the temperature sensor 8. In particular, FIGS. 3 and 4 illustrate the influence of the perspective of the temperature sensor 8 on its measurement, and how the pathway and the position of the asphalt layer 11, and thus the position of the road roller 1 on the asphalt layer 11 transversely to the road pathway, can be inferred from this measurement. FIG. 3 shows a side view similar to the views of FIGS. 1 and 2. As is evident from FIG. 3, the region measured by the temperature sensor 8 has a sensing depth 15 in the working direction a, i.e., parallel to the road pathway. FIG. 4 shows a perspective view of the thermal image 13 captured by the temperature sensor 8. The thermal image 13 captured by the temperature sensor 8 has a sensing width 16 and a sensing depth 15, which limit the thermal image 13 overall. The thermal image 13 is entirely composed of sensor segments 14, each sensor segment 14 being, e.g., one pixel of the resolution of the thermal image camera acting as the temperature sensor 8. In the embodiment shown, the thermal image 13 consists of 164 pixels.
(14) As is also clear from FIG. 4, the thermal image 13 of the temperature sensor 8 is subject to perspective or trapezoidal distortion due to its sensor perspective, which depends on the position of attachment of the temperature sensor 8 on the road roller 1 as well as the measuring angle. This distortion needs to be taken into account in order to calculate the actual pathway of the asphalt layer 11 to be compactedshown in FIG. 4 in a top view as a comparison to the perspective thermal image 13from the measurement data of the temperature sensor 8. FIG. 4, in particular, shows the asphalt layer 11 with a road width 17 and a road section length 18. The asphalt layer 11 is divided into a plurality of width segments 12, in the embodiment shown into thirteen width segments 12 with a width of approximately 1 m. The position of the width segments 12 is defined via their distance either to the left edge 26 or to the right edge 27 of the asphalt layer 11. How the pathway of the asphalt layer 11 is determined from the thermal image 13 of the temperature sensor 8 is evident, in particular, from the superimposition of the asphalt layer 11 and the thermal image 13 in FIG. 4. All sensor segments 14 of the thermal image 13 that display a portion of the asphalt layer 11 and thus measure its temperature show a significantly higher temperature than those sensor segments 14 of the thermal image 13 that display the significantly colder ground adjacent to the asphalt layer 11. The left edge 26 and the right edge 27 of the asphalt layer 11 are determined, in particular, by means of these transitions from the warm or hot asphalt layer 11 to the cold ground. Once the edges 26, 27 have been determined, the width segments 12 can respectively be defined by their distance from the edges 26, 27. It is also evident from FIG. 4 that, once the edges 26, 27 of the asphalt layer 11 are known, the width segments 12 or width segment 12 on which the road roller 1 is currently located can be determined from the thermal image 13 of the temperature sensor 8. The width segments 12 on which the road roller 1 has to be located based on the thermal image 13 shown are designated with 28 in FIG. 4. This way, it is possible to determine statistically in which width segments 12 the road roller 1 has carried out which share of its work.
(15) An objective of the present invention is to provide the operator of the road roller 1 with an aid that gives him a statistical overview of the distribution of his work over the asphalt layer across the road pathway. This orientation aid does not need to be particularly precise, so that simplifications and approximations can be used. For example, generally speaking, slip occurring at the roller drums 5 or the wheels 6 can be neglected statistically. Simplifying matters, it can also be assumed that the paving width of the paver by and large does not change. In spite of these assumptions, the operator of the road roller 1 is still informed of the distribution of the compaction between the individual width segments with sufficient accuracy in accordance with the present invention. The operator's job is thus made significantly easier, as the latter can now concentrate on the actual steering of the road roller 1 instead of having to devote excessive attention to the strict adherence to the rolling pattern. The present invention can also be implemented when several road rollers 1 are in operation. If the road rollers 1 are traveling one after the other, the present invention can simply be implemented individually for each road roller 1 without any changes to the factors described above. If the road rollers 1 are traveling next to each another, the system can simply be used without any changes, the corresponding width segments 12 not processed by the road roller 1 simply being indicated as not processed. Alternatively, the rollers involved in the compaction process exchange the measurement data between each other, so that an overall distribution of the performed compaction work and the contribution of the respective rollers are indicated. It is also possible for the operator to restrict the width of the asphalt layer 11 to be processed via an input means, so that the width of the asphalt layer 11 is included and displayed in the statistical evaluation only up to a certain distance value from either the left edge 26 or the right edge 27.
(16) In FIG. 5, the sequence of a compaction process is shown for further illustration. The asphalt layer 11 to be compacted extends between the uppermost and the lowermost dotted line. The position of the road roller 1 is indicated by the circles marked with Roman numerals, at which the rolling width of the road roller 1 and thus its rolling track are respectively suggested. Starting from position I, the roller moves to position II, from there to position III, etc., until it reaches position XIV. In the process, it reverses at the positions V and X. As indicated by the double arrows between positions I and II, the road roller 1 is driven here with its two roller drums 5 in flush alignment one behind the other, so that the total rolling width of the road roller 1 essentially corresponds to the width of one of the roller drums 5. At position XII, the road roller 1 then switches to the crab-steering mode, so that the rolling width of the road roller 1 widens, as indicated by the dash-dot lines. The crab-steering mode is also illustrated between the positions XIII and XIV by means of the roller drums 5, which are offset outwards and parallel to one another, as suggested by the double arrows.
(17) As suggested by the dotted lines in FIG. 5, the asphalt layer 11 has been divided into five width segments 12 transversely to the longitudinal direction. The position of the road roller 1 transversely to the longitudinal direction of the asphalt layer 11 is now determined via the temperature sensor 8. The working performance of the road roller 1 is then quantified as described above. For example, the distance traveled is determined by means of odometry or the number of vibrations of a roller drum 5 elicited by a vibration exciterso-called compaction strokesare counted. The working performance determined in this fashion is then assigned to the appropriate width segment 12 based on the position of the road roller 1 on one of the width segments 12. In a simple embodiment, this can be done, for example, using the center point of the road roller 1, suggested by the circles at the respective positions shown in FIG. 5. Thus, in the example shown, e.g., waypoints I-III would be assigned to the uppermost width segment 12, waypoints IV and V would be assigned to the second width segment 12 counted from the top, waypoints VI-X to the third width segment 12 from the top, and waypoints XI-XIV to the fourth width segment. No working performance would be recorded for the lowermost width segment 12. In order to increase accuracy, the rolling width of the road roller 1 can be incorporated in the statistical evaluation. For example, by virtue of the known rolling width of the road roller 1 and its position, it can be determined which portion of which roller drum 5 respectively compacts the asphalt layer 11 on which width segment 12. The corresponding portions can then be assigned to the respective width segments 12. With such a system, it is also possible to take the crab-steering mode with an overall larger roller width of the road roller 1 into account. For example, the set roller width of the road roller 1 could be stored at each waypoint. Moreover, the respective positions of each roller drum 5 of the road roller 1 could also be recorded or stored. The accuracy of the method according to the present invention can be increased significantly by taking the actual roller width and its overlap on the individual width segments 12 into account. As explained above, it is also possible to start by determining the position of the road roller and the further parameters such as the current rolling width only, so that the division of the asphalt layer 11 into width segments 12 does not occur until the statistical evaluation of the data is performed.
(18) FIGS. 6 and 7 illustrate different examples of displays 29, which present the registered data and their statistical evaluation to the operator of the road roller 1 in order to assist the latter during a working operation. The displays 29 here are configured, e.g., as bar charts. Each bar 31 represents a width segment 12 of the asphalt layer 11. In FIG. 6, for example, the asphalt layer 11 has been divided into three width segments 12, the central width segment 12 being wider than the width segments 12 located at the edge of the asphalt layer 11. This is suggested by bars 31 with different widths in the display 29 of FIG. 6, the width of the bars 31 being proportional to the width of the width segments 12. The height of the bars 31 represents the quantified working operation that has been registered and evaluated for the respective width segments 12. In the embodiment shown in FIG. 6, the middle width segment 12 has thus been compacted to a greater extent, i.e., this segment has received a higher compaction performance of the road roller 1 than the two width segments 12 located at the edges of the asphalt layer 11. In the embodiment shown with bars 31 with different widths, the working performance on the area of the asphalt layer 11 respectively represented by the width of the bars 31 is converted, so that bars 31 of the same height represent an even compaction. Of course, it is also possible to select the width segments 12 with respectively the same width. In addition to the bars 31, a position indicator 30 is also provided in the display 29 which indicates the current position of the road roller 1 or roller drum 5 transversely to the road pathway. The width of the position indicator 30 can also be used to indicate the current roller width of the road roller 1, so that, e.g., the position indicator 30 widens when the road roller 1 switches to crab steering. In the display 29 according to FIG. 7, the asphalt layer 11 has been divided into five width segments 12 of equal width. As described above, a position indicator 30 indicates the current position of the road roller 1 transversely to the asphalt layer 11. In the example shown in FIG. 7, two road rollers 1 are being operated in order to compact the asphalt layer 11 jointly. Both road rollers 1 carry out the method according to the present invention and are in communication with each other via radio. In particular, the two road rollers 1 exchange their statistical evaluations. This way, it is possible for the statistical evaluation of the working operation of the other road roller 1 to be displayed to the operator of the first road roller 1, as indicated by the dashed bars 31 in FIG. 7. This way, the operator always has a full overview of the progress of the compaction of the entire asphalt layer 11, even if he himself only compacts a portion of the asphalt layer 11. If necessary, each bar 31 can show additional information such as temperatures or the like by means of colors or displayed numbers.
(19) FIG. 8 shows a flow chart of the method 19 according to the present invention. The method 19 starts at step 20 with the detection of the edges 26, 27 delimiting the hot asphalt layer 11 transversely to the road pathway by means of the temperature sensor 8. In step 21, the detected asphalt layer 11 is then divided into at least two width segments 12 across the road pathway. In step 22, the position of the road roller 1 on the asphalt layer 11 transversely to the road pathway is determined from the measurement of the temperature sensor 8 and assigned to one of the width segments 12. In step 23, the working operation of the road roller 1 on the width segment 12 is quantified as described above by means of an operating parameter, which is then stored in step 24, e.g., in a rolling memory system of the control unit 9. In step 25, the quantified working operation for each width segment 12 in a past working interval is displayed to the operator of the road roller 1. As also shown in FIG. 5, these steps 20 to 25 are performed in a continuous sequence one after the other, so that the operator of the road roller 1 is constantly provided with a display of a current statistical evaluation of the past working interval. This way, the operator is able to adapt the operation not only to the work already preformed but rather as soon as he determines that an uneven processing of the asphalt layer 11 may result if he simply continues to work without making any adjustments. In this manner, the overall quality of the base course can be improved, which increases its life span. At the same time, the job of the operator of the road roller 1 is made easier in a simple and cost-effective manner.
(20) While the present invention has been illustrated by description of various embodiments and while those embodiments have been described in considerable detail, it is not the intention of Applicants to restrict or in any way limit the scope of the appended claims to such details. Additional advantages and modifications will readily appear to those skilled in the art. The present invention in its broader aspects is therefore not limited to the specific details and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of Applicant's invention.
