Method and system for trimming asphalt heat map data

Abstract

In one aspect, a method of determining a lateral edge of an asphalt mat deposited by a paving machine includes obtaining thermal image data of the asphalt mat at a thermal measurement device associated with the paving machine and determining a lateral edge of the asphalt mat on the paving machine based on a threshold temperature value and the thermal image data. Other aspects include a method of generating a thermal map of an asphalt mat formed by a paving machine and a system for determining a lateral edge of an asphalt mat deposited by a paving machine.

Description

Technical Field

[0001] This disclosure generally relates to a method and system for generating heat mapping data for asphalt pads, and more specifically to a method for trimming heat mapping data for asphalt pads. Background Technology

[0002] Thermal mapping data of the asphalt pad deposited by the paver is used to assess the uniformity of the asphalt pad in terms of compaction and density, and to verify the actual size of the asphalt pad. For example, irregularities in compaction and density may occur if the ambient temperature or paver temperature is low, or if the paving material supply has varying temperatures. Maintaining compaction uniformity ensures a reduction in cracks in the asphalt pad, which can lead to potholes if water seeps into them. Maintaining compaction uniformity also ensures a reduction in streaks in the asphalt pad. Maintaining density uniformity ensures a reduction in soft spots in the asphalt pad (which can also lead to cracks and potholes). Setting levels of compaction and density uniformity for the asphalt pad helps ensure its lifespan.

[0003] In addition, local or government agencies may need to use thermal mapping data of the asphalt pads to ensure compliance with the specifications of the construction contract. For example, a local or government agency may need to transmit thermal mapping data for each batch deposited by the paver (i.e., the rectangular area of ​​asphalt deposited, having a predetermined width and length). The thermal data to be transmitted may need to conform to the specifications of the construction contract issued by the agency. For example, if the transmitted thermal mapping data indicates a density uniformity of less than 85%, the agency may reduce payments under the construction contract.

[0004] Known thermal profiling systems record thermal data within the field of view of a thermal measuring device (such as a thermal camera or hot wire scanner). These systems capture both desired data (i.e., the temperature value of the hot asphalt pad) and unwanted data (i.e., temperature values ​​along the sides of the asphalt pad), covering a range as wide as the thermal measuring device can record. The unwanted thermal data increases the amount of data that must be stored and requires users to post-process the data using third-party applications (such as Veta) to remove unwanted data before the temperature of the hot asphalt pad can be analyzed.

[0005] This post-processing may also require the user to determine the edges of the asphalt map before performing trimming of the heat mapping data. To this end, some paving devices include sensors positioned at the outer edge of the entire slab to measure the width of the asphalt map. However, problems arise when only a portion of the paving device (i.e., one side) is used to deposit asphalt (i.e., forming a narrower asphalt pad), as is the case in dead ends or junctions of paved roads. When sensors are positioned at each end of the entire slab of the paving device, the sensors may not reflect the actual width of this narrower asphalt pad. Therefore, these paving devices require the user to further refine the thermal data by removing data from those areas outside the edges of the narrower asphalt pad.

[0006] Furthermore, when the paving device uses infrared (IR) sensors to acquire infrared (IR) data of the asphalt pad, IR data for individual points on the asphalt pad is acquired as the paver moves. The acquired IR data may not be captured along the true line (i.e., a line perpendicular to the axis along which the paver moves and spans the width of the asphalt pad). Additionally, if the paver's speed increases, the IR sensor may not necessarily increase the frequency of IR data acquisition, thus IR data may be lost. Therefore, the thermal data output by such a paving device may not necessarily include all thermal data of the asphalt pad corresponding to a batch (i.e., a rectangular area) and may be incomplete.

[0007] The method for trimming asphalt pad heat mapping data according to this disclosure can solve one or more of the problems mentioned above and / or other problems in the prior art. However, the scope of this disclosure is defined by the appended claims, and not by its ability to solve any particular problem. Summary of the Invention

[0008] In one aspect, a method for determining the lateral edge of an asphalt pad deposited by a paver may include obtaining thermal image data of the asphalt pad at a thermal measurement device associated with the paver; and determining the lateral edge of the asphalt pad on the paver based on a threshold temperature value and the thermal image data.

[0009] In another aspect, a method for generating a thermal map of an asphalt pad formed by a paver may include: generating thermal image data of the asphalt pad at a thermal measurement device associated with the paver, the thermal image data including a plurality of scan lines of thermal image data spanning the field of view of the thermal measurement device; determining lateral edges of the asphalt pad on the paver based on the plurality of scan lines and a threshold temperature value; and generating a thermal map of the asphalt pad, the thermal map including thermal image data of the plurality of scan lines between the lateral edges of the asphalt pad.

[0010] In another aspect, a system for determining the lateral edge of an asphalt pad deposited by a paver may include: a thermal measuring device configured to acquire a thermal image of the asphalt pad, the thermal image including thermal image data of the asphalt pad; at least one memory storing an instruction set; and at least one processor configured to execute instructions of the instruction set to determine the lateral edge of the asphalt pad on the paver based on a threshold temperature value and the thermal image data. Attached Figure Description

[0011] Figure 1 A schematic diagram of a paving apparatus and asphalt pad according to the present disclosure is shown;

[0012] Figure 2 A schematic diagram of the thermal measurement device and the controller of the paving device according to this disclosure is shown;

[0013] Figure 3 A flowchart of a method for generating and outputting a thermal map of an asphalt pad according to this disclosure is shown;

[0014] Figure 4 Details of a method for obtaining trimming data points and lateral edges of an asphalt pad according to this disclosure are shown;

[0015] Figure 5 The heatmap data set is shown, including data that will be removed using a user-defined temperature threshold;

[0016] Figure 6 A graph of the heatmap data is shown, depicting outliers, median, first quartile, second quartile, and interquartile range;

[0017] Figure 7 A graph showing the temperature and pixel values ​​of the thermal mapping data; and

[0018] Figure 8 The heatmap dataset is shown, including data that will be removed using a user-defined temperature threshold and data that will be removed using a temperature threshold determined by using interquartile range.

[0019] The foregoing general description and the following detailed description are exemplary and illustrative only, and do not limit the claimed features. As used herein, the terms “comprise,” “comprising,” “having,” “including,” or other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article of manufacture, or apparatus that includes a list of elements includes not only those elements, but may also include other elements not expressly listed or inherent to such process, method, article of manufacture, or apparatus. Furthermore, in this disclosure, relative terms, such as “about,” “substantially,” “basically,” and “approximately,” are used to indicate possible variations of ±10% in the stated values. Detailed Implementation

[0020] refer to Figure 1 The thermal mapping system 100 for the paving device 102 includes at least a thermal measurement device 104 and a controller 106. The paving device 102 can be any conventional paving device or machine and may include a hopper 110, a cab 112, at least one auger 114, and a slab 116. The thermal measurement device 104 and the controller 106 can be mounted on the paving device 102. The thermal measurement device 104 can be an optical temperature sensor that captures thermal images using infrared radiation, such as a thermal camera or a hot-wire scanner. The thermal measurement device 104 has a field of view 108 and is shown mounted on the cab 112 of the paving device 102 in such an orientation that the thermal measurement device 104 is configured to capture thermal data of each scan line A of the asphalt pad 118 deposited on the working surface located behind the slab 106 as the paving device 102 advances. That is, as the paving device 102 moves along... Figure 1 As the thermal measuring device 104 advances along the working surface in the direction indicated by arrow B, it faces the opposite direction to arrow B and captures thermal data for each scan line A of the asphalt pad 118, thereby obtaining multiple scan lines A that form a complete thermal map of the asphalt pad 118. However, this disclosure is not limited to this arrangement of the thermal measuring device 104, and the thermal measuring device 104 may be mounted to other parts of the paving device 102 or may be held by the user. The paving device 102 forms an asphalt pad 118 having two opposing lateral edges 120, 122.

[0021] refer to Figure 2 The controller 106 includes at least one memory device 124 and at least one processor 126. The memory device 124 includes suitable logic, circuitry, interfaces, and / or code that can be configured to store a set of instructions executable by the processor 126. In embodiments, the memory device 124 may be configured to store one or more programs, routines, or scripts that can cooperate with the processor 126 to perform... Figure 3 and 4 Method 300 is shown. The memory device 124 also stores thresholds, including user-defined temperature thresholds and calculated temperature thresholds, which can be used by method 300. The memory device 124 can be random access memory (RAM), read-only memory (ROM), hard disk drive (HDD), storage server, and / or secure digital card (SD card).

[0022] Processor 126 reads and executes the instruction set to perform Figure 3 and Figure 4 The method 300 shown is described above. The controller 106 is configured to control the operation of the heat mapping system 100 based on thermal image data output from the thermal measurement device 104 and a program executed by the processor 126. The processor 126 may be, for example, a central processing unit (CPU). However, the memory device 124 and the processor 126 are not limited to the devices listed above.

[0023] The heat mapping system 100, and more specifically, the controller 106, is configured to receive input and provide output in any suitable manner. For example, a user can provide input via an input device 128 (e.g., a user interface on the paving device 102). For example, a user can input a user-defined threshold temperature value T1 via the input device 128. Alternatively, a user can provide input remotely. Furthermore, the controller 106 can provide output via an output device 130, such as a display of the user interface, or provide output to an interface located remotely from the paving device 102.

[0024] Industrial applicability

[0025] The thermal mapping system 100, and more specifically, the method performed by the controller 106 of the thermal mapping system 100, can provide thermal mapping data for the trimming of the asphalt pad 118, while reducing or eliminating the need for manual adjustment or verification during the trimming of the thermal mapping data.

[0026] Figure 3 and Figure 4 A flowchart is shown of a method 300 performed by a controller 106 using thermal image data obtained using a thermal measurement device 104 of a thermal mapping system 100.

[0027] Specifically, Figure 3A method 300 for generating and outputting a thermal image of an asphalt pad 118 is described. For example, in step 302, thermal image data is obtained using a thermal measurement device 104 and provided or transmitted to a controller 106. In step 304, the lateral edges 120, 122 of the asphalt pad 118 are determined, and in step 306, the controller 106 generates and outputs a thermal image of the asphalt pad 118 based on the determined lateral edges of the asphalt pad 118.

[0028] More specifically, in step 302, thermal image data can be acquired by the thermal measurement device 104 and transmitted to the controller 106. (See reference...) Figure 5 The thermal image data can be a thermal image 128 captured by the thermal measurement device 104. The thermal image data may include pixels 130 or data points, each pixel or data point having: a pixel value, i.e., the coordinate value of pixel 130; and a corresponding measured temperature value. The thermal image data may correspond to multiple scan lines A( Figure 1 Each scan line A includes pixels 130 with pixel values ​​and corresponding measured temperature values.

[0029] Figure 3 Step 304 in all aspects Figure 4 The details are provided in more detail below. For example, step 304 may include step 404, wherein pixels 132 in a plurality of pixels 130 of the thermal image 128 are pruned based on the relationship between the corresponding measured temperature value and a user-defined threshold temperature value T1 to determine the lateral edges 120, 122 of the asphalt pad 118. That is, in step 304, the lateral edges 120, 122 of the asphalt pad 118 are determined based on the threshold temperature value T1 and the thermal image data. This step may include pixel analysis, wherein the measured temperature value of each pixel 130 of the obtained thermal image 128 is compared with the user-defined threshold temperature value T1. This step may also include the identification and pruning of pixels 130 whose measured temperature values ​​are less than the user-defined threshold temperature value T1. That is, starting from each edge of the thermal image 128 of scan line A, the measured temperature value of each pixel 130 is compared with the user-defined threshold temperature value T1. If the measured temperature value of pixel 130 is less than the user-defined threshold temperature value T1, then pixel 130 is deleted (i.e., it is pruned) and is referred to as pruned pixel 132. The comparison of measured temperature values ​​can be performed starting from the edge of thermal image 128 until the measured temperature value of pixel 130 is greater than or equal to the user-defined threshold temperature value T1, i.e., pixel is the edge pixel 130e. Figure 5As shown, pixel 130e defines the edges 134 and 136 of the initial trimmed thermal image 138. Pixels outside the edge pixel 130e are trimmed, i.e., they are trimmed pixels 132. The resulting initial trimmed thermal image 138 differs from thermal image 128 in that the trimmed pixels 132 are removed, i.e., pixels with measured temperature values ​​less than a user-defined threshold temperature value T1 are removed, and the initial trimmed thermal image 138 includes only the remaining pixels 140.

[0030] Next, in step 406, the interquartile range (IQR) of the temperature values ​​of pixel 140 in the initial trimmed thermal image 138 is calculated. In this step, the first quartile value Q1 (i.e., the 25th percentile), the second quartile value or median M, and the third quartile value Q3 (i.e., the 75th percentile) of the temperature values ​​of pixel 140 are calculated. More specifically, a list of temperature values ​​of pixel 140 in the initial trimmed thermal image 138 is generated in ascending order from lowest to highest value. If the list contains an odd number of temperature values, the median M is the middle value in the list. If the list contains an even number of temperature values, the median M is the average of the two middle values ​​in the list.

[0031] Temperature values ​​below the median M constitute the lower half of the list. The first quartile, Q1, is the median of the lower half, and the third quartile, Q3, is the median of the upper half. If the lower half contains an odd number of temperature values, then the first quartile, Q1, is the median of the lower half. If the lower half contains an even number of temperature values, then the first quartile, Q1, is the average of the two medians of the lower half.

[0032] Similarly, if the upper half of the list contains an odd number of temperature values, then the temperature values ​​greater than the median M constitute the upper half of the list, and the third quartile value Q3 is the median of the upper half. If the upper half of the list contains an even number of temperature values, then the third quartile value Q3 is the average of the two medians of the upper half. Figure 5 As shown, IQR is equal to the difference between the first quartile value Q1 and the third quartile value Q3. That is, IQR = Q3 - Q1.

[0033] In step 408, another threshold temperature value T2 (i.e., the calculated or second threshold temperature value) is calculated. The calculated threshold temperature value T2 can be determined based on the first quartile value Q1 and IQR. For example, the calculated threshold temperature value T2 can be calculated using the following equation: T2 = Q1 – 1.5 × IQR.

[0034] In step 410, based on the relationship between the corresponding measured temperature value and the calculated threshold temperature value T2, pixels 140 of the initial trimmed thermal image 138 are trimmed as part of the pixel analysis. More specifically, starting from each end of the initial trimmed thermal image 138, the measured temperature value of each pixel 140 is compared with the calculated threshold temperature value T2. If the measured temperature value of pixel 140 is less than the calculated threshold temperature value T2, then pixel 140 is deleted (i.e., it is trimmed pixel 142).

[0035] Figure 7 A graph showing the measured temperature and pixel values ​​of thermal image 142 is displayed. (See figure.) Figure 7 As shown, trimmed pixels 142 are those pixels whose measured temperature values ​​are less than the calculated threshold temperature value T2. Trimmed pixels 142 correspond to pixels 140 at the edges of thermal image 138, that is, pixels 140 with pixel values ​​close to one of the two edges 134, 136 of thermal image 138. The final trimmed thermal image 150 differs from the initial trimmed thermal image 138 in that pixels 142 whose measured temperature values ​​are less than the calculated threshold temperature value T2 are removed, and the final trimmed thermal image 150 includes only the remaining pixels 148. Figure 8 As shown, the edges of the remaining pixels 148 define the edges 144 and 146 of the final trimmed thermal image 150. The edges 144 and 146 of the final trimmed thermal image 150 correspond to the lateral edges 120 and 122 of the asphalt pad 118. Step 304 then ends.

[0036] Next, return to the reference. Figure 3 In step 306, a thermal map of the asphalt pad 118 is generated and / or output. That is, after determining the lateral edges 120, 122 of the asphalt pad 118 using a user-defined threshold temperature value T1 and a threshold temperature value T2 calculated in step 304, a thermal map of the asphalt pad 118 can be generated. Specifically, the generation of the thermal map may include outputting the final trimmed thermal image 150 determined in step 304 to the output device 130. The width and length of the final trimmed thermal image 150 correspond to the width and length of the thermal map of the asphalt pad 118. The final trimmed thermal image 150 constitutes the thermal map of the asphalt pad 118. The output of the thermal map may include, for example, outputting the thermal map to a user's database for transmission to an institution for thermal map analysis, or outputting the thermal map directly to the institution's database for analysis. Then, method 300 ends.

[0037] Although method 300 is described as including steps 302 to 306, and detailed steps 404 to 410 including step 304, method 300 does not necessarily include all of these steps. For example, method 300 may only include: step 302, in which a thermal image 128 is obtained; step 404, as part of step 304, in which the measured temperature values ​​of pixels 130 in thermal image 128 that are less than a user-defined threshold T1 are cropped to obtain a cropped thermal image 138; and step 306, in which a thermal image is generated and / or output. In this embodiment, the thermal image is formed from the initial cropped thermal image 138.

[0038] Additionally, although the pixel analysis in steps 404 and 410 is described as starting from each end of the thermal image 128 or the initially trimmed thermal image 138, the pixel analysis in both steps may correspondingly include a comparison of the measured temperature values ​​of each pixel 130 of each scan line A of the thermal image 128 or the initially trimmed thermal image 138. The pixel analysis in this embodiment stops when all pixels 130 have been compared.

[0039] Embodiments of this disclosure cover methods for determining the lateral edges of an asphalt pad deposited by a paver using thermal images captured by a thermal measurement device and threshold temperature values. Additionally, embodiments of this disclosure cover methods for generating thermal maps of an asphalt pad formed by a paver using thermal image data of the asphalt pad and threshold temperature values. Furthermore, embodiments of this disclosure cover systems for determining the lateral edges of an asphalt pad deposited by a paver using thermal images captured by a temperature measurement device and threshold temperature values, and / or for generating thermal maps of the asphalt pad using thermal image data of the asphalt pad and threshold temperature values.

[0040] By utilizing the thermal mapping system and related methods of this disclosure, thermal mapping data of an asphalt pad deposited by a paving apparatus can be obtained, including lateral edges and / or thermal maps, to verify the actual size of the asphalt pad and / or analyze temperature values ​​in the thermal mapping data, while eliminating unwanted data, i.e., temperature values ​​along the sides of the asphalt pad. The systems and methods of this disclosure facilitate obtaining trimmed thermal image data with less required input and / or user adjustments before, during, or after obtaining the thermal image data. Furthermore, the thermal mapping data obtained according to the systems and methods of this disclosure may require less or no post-processing for subsequent analysis (i.e., the output data can be stored and processed by a third-party application without user modification), which in turn improves the efficiency of storing and transmitting thermal mapping data to the apparatus. Moreover, the systems and methods of this disclosure provide thermal mapping data of the asphalt pad, which includes a complete set of data points along the true line (i.e., a line perpendicular to the axis along which the paver moves), thereby improving the accuracy and precision of the thermal mapping data. Furthermore, the systems and methods disclosed herein provide iterative analysis of measured temperature values, which facilitates the elimination of measured temperature values ​​at locations outside the asphalt pad, i.e., unwanted data, by using user-defined temperature thresholds and temperature thresholds calculated in part based on interquartile range.

[0041] Various modifications and alterations can be made to the disclosed system without departing from the scope of this disclosure, as will be apparent to those skilled in the art. Other embodiments of the capability-enhancing system disclosed herein will be apparent to those skilled in the art in light of the description and practice thereof. The specification and examples are intended to be considered exemplary only, and the true scope of this disclosure is defined by the following claims and their equivalents.

Claims

1. A method of determining lateral edges of an asphalt mat deposited by a paving machine using pixel analysis, the method comprising: obtaining thermal image data of the asphalt mat using a thermal measurement device disposed on the paving machine laying the asphalt mat facing in a direction opposite to a direction of movement of the paving machine, the thermal image data comprising pixels and having corresponding measured temperature values; and determining lateral edges of the asphalt mat on the paving machine using the pixel analysis, the pixel analysis comprising: for each pixel starting from an edge of the thermal image, comparing a corresponding measured temperature value of the pixel to a threshold temperature value, if the corresponding measured temperature value of the pixel is less than the threshold temperature value, pruning the pixel from the thermal image, and repeating the comparing step and the pruning step to determine edge pixels comprising pixels whose corresponding measured temperature values are not less than the threshold temperature value, the edge pixels defining the lateral edges of the asphalt mat to generate a pruned thermal image of the asphalt mat.

2. The method of claim 1, wherein the lateral edges are opposite lateral edges of the asphalt mat.

3. The method of claim 1, wherein the threshold temperature value is a user-defined temperature.

4. The method of claim 1, wherein the determining is further based on thermal image data spanning a width of the asphalt mat.

5. The method of claim 1, wherein the threshold temperature value is a first threshold temperature value, the trimmed thermal image is a first trimmed thermal image, and wherein, the pixel analysis further comprising: as a second comparing step, for each pixel starting from each end of the first pruned thermal image, comparing a corresponding measured temperature value to a second threshold temperature value, the second threshold temperature value being greater than the first threshold temperature value, as a second pruning step, if the corresponding measured temperature value of the pixel is less than the second threshold temperature value, pruning the pixel from the first pruned thermal image, and repeating the second comparing step and the second pruning step to generate a second pruned thermal image of the asphalt mat.

6. The method of claim 5, wherein, the pixel analysis further comprising calculating the second threshold temperature value using an interquartile range of the thermal image data having temperature values greater than or equal to the first threshold temperature value.

7. The method of claim 6, wherein the interquartile range of the thermal image data is equal to a difference between a first quartile value and a third quartile value of the thermal image data.

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