Edge detection system, screed and road paver

Abstract

The utility model relates to an edge detection system which is used for a road paver and comprises a sensor unit which comprises a transmitting module for transmitting laser pulse sequences in multiple directions to enable the laser pulse sequences to be reflected at multiple positions of a surface to be scanned, a monitoring module for detecting the reflection of the laser pulse sequences, and a processing module for processing the laser pulse sequences, a signal generation module that generates a polar coordinate signal representing polar coordinates based on the detected reflections, where the polar coordinates include a distance and a correlation angle; a conversion unit configured to convert the polar coordinate signal into a Cartesian coordinate signal representing Cartesian coordinates; and a first determination unit configured to determine a position of an edge in the surface to be scanned relative to the Cartesian coordinate system based on the Cartesian coordinate signal. The utility model further relates to an ironing plate for the road paver and the road paver comprising the edge detection system.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of edge monitoring systems for detecting edge as the reference of laying road pavement, a kind of screed including the edge monitoring system and a kind of road paver including the edge monitoring system or screed. BACKGROUND

[0002] Road pavement (e.g. asphalt layer) is usually laid using a road paver. To provide the desired course of the road pavement, in particular of its side edges, references are used along which the road paver, in particular its screed, can be guided. These references include lines or edges. Examples of edges used as references are curb edges, edges of previously laid pavement layers or milling edges resulting from the removal of pavement layers to be replaced. Guiding the road paver or the screed or an extended portion thereof to travel in a reference direction is still usually achieved by manual control by an operator. Further automation is desirable. One challenging goal is to detect the course of the reference. WO 2020 088782 A1 discloses a sensor system for a construction machine, in particular a road paver, comprising a laser scanner. This is to enable tracking by maneuvering the road paver or an extended or retracted extendable screed portion. SUMMARY

[0003] It is an object of the utility model to provide an improved system for edge detection.

[0004] The utility model discloses an edge detection system for road paver. The edge detection system includes sensor unit. The sensor unit includes emission module, it is configured to emit laser pulse sequence to multiple directions, so that laser pulse sequence is reflected at multiple positions of the surface to be scanned. Sensor unit further includes: detection module, it is configured to detect the reflection of laser pulse sequence, and, signal generation module, it is configured to generate polar coordinate signal representing polar coordinates based on the detected reflection, wherein, polar coordinates include distance value and related angle value. The edge detection system further includes: conversion unit, it is configured to convert polar coordinate signal into cartesian coordinate signal representing cartesian coordinates, and, first determination unit, it is configured to determine the position of edge in the surface to be scanned relative to cartesian coordinate system based on cartesian coordinate signal. Conversion into cartesian coordinate signal can realize some processing techniques, which do not need radiation intensity compared with the method of prior art.

[0005] The surface to be scanned can be, for example, a foundation or a part of a foundation on which a road paver is driving or paving a road surface. In addition to the sensor unit, the edge detection system can comprise further components, for example one or more units for controlling movement, data processing and / or communication. The components of the edge detection system can be interconnected in order to, for example, transmit signals and / or exchange data. For example, the connections between the components of the edge detection system can comprise one or more Ethernet connections and / or one or more CAN bus connections. The edge detection system can comprise a plurality of sensor units. Each sensor unit can have an address, for example an IP address. The address can be statically programmed into each sensor unit or assigned to each sensor unit, for example by the sensor identification unit. For example, the sensor identification unit can be configured to assign an address to one, several or all sensor units based on a connector by which the respective sensor unit is connected to the sensor identification unit.

[0006] The above-mentioned units can be configured to perform various functions of the edge detection system. For example, the above-mentioned units can be implemented as separate electronic circuits or as part of a central control unit of the screed or a central control unit of the road paver. The sequence of laser pulses can be understood as a laser signal comprising a finite number of cycles, in particular one or more cycles.

[0007] In the following, the expression "function" will be used in the general mathematical sense. For example, it can be understood as a relation between two sets, wherein each element of the first set is assigned to a corresponding element of the second set. The relation can be given, for example, by a mathematical formula or a plurality of, for example discrete, ordered pairs, for example coordinate pairs. The ordered pairs can each comprise an argument, for example a first coordinate or x-coordinate, and a value of the function, for example a second coordinate or y-coordinate or a slope. The edge detection system can comprise an interpolation unit configured to determine an interpolation function based on the Cartesian coordinate signals. The interpolation function can be regarded as a representation of a profile of the surface to be scanned. Characteristic positions of the profile can be determined mathematically by curve fitting.

[0008] The edge detection system can comprise a smoothing unit configured to determine a smoothed function based on the interpolation function and / or based on the Cartesian coordinate signals. Smoothing can avoid errors in the evaluation, for example due to noise in the measured function that is not smoothed. The smoothed function can comprise a plurality of ordered pairs. For example, the ordered pairs can each comprise a first coordinate or x-coordinate as an argument and a second coordinate or y-coordinate as a value of the function.

[0009] The edge detection system can comprise a differentiation unit configured to differentiate the smoothed function and to determine a derivative function. The derivative function can comprise a plurality of ordered pairs. For example, the ordered pairs can each comprise a first coordinate or x-coordinate as an argument and a slope, e.g. a slope of the smoothed function at the respective argument or respective x-coordinate, as a value of the function. Since the derivative function can represent a run of slopes of the smoothed function, it is possible to determine where a change in direction of a profile of the surface to be scanned lies by evaluating the derivative function.

[0010] The edge detection system can comprise a second determination unit configured to determine a smallest minimum and / or a largest maximum of the derivative function. For example, the derivative function can be differentiated once more and then the zero points of the resulting second derivative function can be determined. The second determination unit can also be configured to ignore positions of the derivative function at which the value of the derivative function is smaller than a threshold value when determining the smallest minimum and / or the largest maximum of the derivative function. This way it is possible to avoid that randomly distributed values are continuously outputted in the absence of a distinct extremum.

[0011] The edge detection system can comprise a third determination unit configured to determine an edge distance value based on the argument of the derivative function at the smallest minimum and / or at the largest maximum, which edge distance value can represent an edge distance between an edge in the surface to be scanned and the sensor unit.

[0012] The emission module of the sensor unit can also be implemented as a 2-D lidar sensor. The emission module can be configured to emit a sequence of laser pulses in the infrared spectrum. For example, the sensor unit can be configured to emit infrared laser pulses. The detection module of the sensor unit can also be implemented as a photodiode. The photodiode can be configured to detect reflections of the sequence of laser pulses, e.g. reflections in the infrared spectrum and / or reflections of the infrared laser pulses. The sensor unit or the edge detection system can be configured to determine the distance value based on a time-of-flight measurement.

[0013] All of the plurality of directions can lie in the same plane. The sensor unit may, for example, comprise a rotating mirror. The mirror can be configured to deflect the sequence of laser pulses in the infrared spectrum and / or the infrared laser pulses into the plurality of directions. The sensor unit or the edge detection system can also be configured to determine the angle value based on an orientation of the mirror. The rotation frequency of the mirror can be between 1 Hz and 100 Hz, in particular between 1 Hz and 50 Hz, particularly preferably between 1 Hz and 30 Hz. The rotation frequency of the mirror may, for example, be 15 Hz. The sensor unit and / or the edge detection system can be configured to evaluate the measurement values in a range of -35° to 35°.

[0014] The edge detection system can further comprise a second sensor unit and the sensor identification unit can be configured to distinguish between the sensor unit and the second sensor unit based on an IP address. Alternatively or additionally, the edge detection system can be configured to distinguish between the sensor unit and the second sensor unit based on the installation position of the sensor unit and the second sensor unit, e.g. the side of the screed and / or the lateral shield on which it is installed. Alternatively or additionally, the edge detection system can be configured to distinguish between the sensor unit and the second sensor unit based on a connector by which the respective sensor unit is connected to other components of the edge detection system, e.g. the sensor identification unit.

[0015] The utility model further relates to a screed of a road paver comprising an edge detection system of the above type. The screed can comprise at least one extension, preferably two extensions. The edge distance can be defined parallel to the extension direction of the extension. The movement of the extension or extensions can be controlled based on the output of the edge detection system.

[0016] The sensor unit can be provided on one, several or all extensions of the screed. In particular, a lateral shield can be installed on one, several or all extensions of the screed. The one or more sensor units can be provided at one of the lateral shields, respectively. The one or more sensor units can be provided at the extension or the lateral shield, respectively, such that the plane is at an angle to the surface to be scanned, the angle being greater than 0° and less than 180°, in particular 90°.

[0017] The screed can have a path measurement device and / or a width control device. The path measurement device can be configured to determine the extension path of each extension. The width control device can be configured to set a predetermined target by moving one or several or all extensions.

[0018] The utility model further relates to a road paver comprising an edge detection system of the above type or a screed of the above type. The plane can form an angle of greater than 0° and / or less than 180°, preferably of greater than 75° and / or less than 105°, to the direction of travel of the road paver. In particular, the plane can be oriented orthogonally to the direction of travel of the road paver. Brief description of the drawings

[0019] Figure 1 A schematic side view of a road paver with an edge detection system is shown.

[0020] Figure 2 A schematic top view of a road paver is shown. Figure 1

[0021] Figure 3 A schematic top view of a road paver is shown.​Figure 1 and Figure 2 schematic detail view of a rear part of a road paver.

[0022] Figure 4 schematic diagram showing an interpolated function generated based on exemplary distance measurements.

[0023] Figure 5 schematic diagram showing a smoothed function generated based on Figure 4

[0024] Figure 6 schematic diagram showing a derivative function generated based on Figure 5

[0025] Figure 7 schematic diagram showing connections between various components of a road finisher. Figures 1 to 3 DETAILED DESCRIPTION

[0026] In Figure 1 , a road paver 1 is shown in a schematic side view. The road paver 1 can comprise a tractor 2. The road paver 1 can further comprise a screed 3. The tractor 2 can be configured to tow the screed 3. To this end, the road paver 1 can comprise a tow arm 4. The road paver 1 can be configured to lay a road surface 5 to a ground base 6. The road paver 1 can be moved in a driving direction 7.

[0027] The screed 3 can further comprise side shields 8. The side shields 8 can be configured to limit a paving width 9 of the screed 3 (see Figure 2 ). In particular, the side shields 8 can be configured to limit the paving width 9 in a direction transverse to the driving direction 7. The road paver 1 can further comprise an edge detection system 10. The edge detection system 10 can comprise a sensor unit 11. The sensor unit 11 can be arranged at one of the side shields 8.

[0028] In Figure 2 , the road paver 1 is shown in a schematic top view as seen from above. It can now be seen that the screed 3 can comprise a base screed 12. Furthermore, as shown in the present embodiment, the screed 3 can comprise two extension parts 13. The extension parts 13 can be movable relative to the base screed 12, in particular in an extension direction 15. The extension direction 15 can be oriented transverse to the driving direction 7, in particular orthogonally. By moving the extension parts 13, the paving width 9 of the screed 3 can be adjusted. In Figure 2 ​​​It can further be seen that the edge detection system 10 can comprise a second sensor unit 14. As shown in the present embodiment, the sensor unit 11 and the second sensor unit 14 can be arranged at opposite extending portions of the screed 3, in particular at opposite side shields 8 of the screed 3.

[0029] In Figure 3 In detail, components of the screed 3 and components of the edge detection system 10 are shown in a perspective view from the rear. It can be seen that the sensor unit 11 can be configured to emit a sequence of laser pulses 16. An emission unit (not shown in the figure) of the sensor unit 11 can be configured to emit the sequence of laser pulses 16 in a plurality of directions 17. As shown in the embodiment, the emission unit of the sensor unit 11 can be configured to emit the sequence of laser pulses 16 such that the sequence of laser pulses 16 is reflected at a plurality of positions 18 on a surface 19 to be scanned. As shown in the embodiment, a portion of the foundation 6 can be regarded as the surface 19 to be scanned.

[0030] The reflections of the sequence of laser pulses 16 can be detected by a detection module (not shown in the figure) of the sensor unit 11. For example, the reflections of the sequence of laser pulses 16 can be detected by a photodiode (not shown) of the sensor unit 11. The sensor unit 11 and / or the edge detection system 10 can further be configured to determine distances of the respective positions 18 to the sensor unit 11 based on the transmission times of the sequence of laser pulses 16 and their reflections. The sensor unit 11 and / or the edge detection system 10 can comprise a signal generation module (not shown in the figure) configured to generate polar coordinate signals based on the distances and the directions 17 of the respective sequence of laser pulses. Each polar coordinate signal can represent a position of the respective position 18 with respect to a polar coordinate system having an origin, which can for example be located inside the sensor unit 11.

[0031] The edge detection system 10 and / or the sensor unit 11 can further comprise a conversion unit (not shown in the figure) configured to generate Cartesian coordinate signals based on the polar coordinate signals. The Cartesian coordinate signals can represent Cartesian coordinates of the respective positions 18 with respect to a Cartesian coordinate system 20. The origin of the Cartesian coordinate system 20 can be located inside the sensor unit 11, in particular at a point where the sequence of laser pulses 16 is reflected in the respective direction 17.

[0032] The edge detection system 10 and / or the sensor unit 11 can comprise an interpolation unit configured to determine an interpolation function 21 (see Figure 4 ) based on the Cartesian coordinate signals. Figure 4 A schematic diagram showing such an interpolation function 21 is shown as an example. The edge detection system 10 and / or the sensor unit 11 can further comprise a smoothing unit configured to determine a smoothed function 22 based on the interpolation function 21. Figure 5A schematic diagram of such a smoothed function 22 is shown as an example. Furthermore, the edge detection system 10 and / or the sensor unit 11 can comprise a differentiation unit configured to determine a derivative function 23 based on the smoothed function 22, in particular by differentiating the smoothed function 22. Figure 6 A schematic diagram of such a derivative function 23 is shown as an example.

[0033] Furthermore, the edge detection system 10 and / or the sensor unit 11 can comprise a second determination unit configured to determine a smallest minimum 24 and / or a largest maximum 25 of the derivative function 23. The edge distance value 26 can be determined based on the smallest minimum 24 of the derivative function 23 and / or based on the largest maximum 25 of the derivative function 23. In particular, the edge detection system 10 and / or the sensor unit 11 can comprise a third determination unit configured to determine the edge distance value 26 based on the smallest minimum 24 of the derivative function 23 and / or based on the largest maximum 25 of the derivative function 23. In the present embodiment, the smallest minimum 24 of the derivative function 23 is taken as a basis for determining the edge distance value 26, as will be explained in further detail below. In particular, the argument of the derivative function 23 at the smallest minimum 24 of the derivative function 23 can be determined as the edge distance value 26. The edge distance value 26 can be regarded as representing the edge distance 27 (see Fig. 2) between the edge 28 (see Fig. 2) in the surface 19 to be scanned and the sensor unit 11. Figure 3 ) with the sensor unit 11. Figure 3

[0034] In Figure 7 , a connection between the edge detection system 10 and the components of the screed 3 is shown schematically. It can be seen that the edge detection system 10 can comprise a sensor identification unit 32. The sensor unit 11 can be connected to a first connector of the sensor identification unit 32. The second sensor unit 14 can be connected to a second connector 34 of the sensor identification unit 32. The connection between the sensor units 11, 14 and the sensor identification unit 32 can for example be embodied as an Ethernet. For example, the sensor unit 11 can have a static IP address, based on which the sensor identification unit 32 can identify the installation side of the sensor unit 11. Similarly, the second sensor unit 14 can have a static IP address, which can be different from the IP address of the sensor unit 11, and based on which the sensor identification unit 32 can determine the installation side of the second sensor unit 14. Alternatively or additionally, the first connector 33 and the second connector 34 can each be assigned to one installation side. In this way, the sensor identification unit 32 can be configured to determine on which installation side each sensor unit 11, 14 is arranged based on the connector to which the respective sensor unit 11, 14 is connected.

[0035] ​The following will be based on Figures 1 to 7 The operation of the edge detection system 10 in cooperation with the road paver 1 will be further explained in a general and exemplary manner. The following explanations mainly refer to the sensor unit 11. However, it should be clear that these explanations also apply to the second sensor unit 14.

[0036] The sensor unit 11 can be arranged at the extension 13, in particular at the side shield 8. As Figure 1 As shown in the present embodiment in

[0037] It can be seen that, according to the present embodiment, the x-coordinate of the Cartesian coordinate system 20 or the argument of a function determined with respect to this coordinate system 20 can be oriented parallel with respect to the extension direction 15 of the extension 13, respectively. In the direction of increasing paving width 9 (left in Figure 3 Figure 3 In the direction of decreasing paving width 9 (right in Figure 3 In order to be able to use the same sensor unit for the sensor unit 11 and the second sensor unit 14, the x-coordinate of a coordinate system (not shown) whose origin is located within the second sensor unit 14 can be oriented such that the x-coordinate becomes more positive in the direction of decreasing paving width 9.

[0038] As explained above with reference to Figure 7 The edge detection system 10 can be configured to automatically identify on which side of the screed 3 the sensor unit 11 and the second sensor unit 14 are arranged. For facilitating the edge detection, the operator can set the type of edge to be detected, for example, whether an edge sloping upwards or downwards to the outside should be detected. For example, during setting of the respective sensor units 11, 14, the edge detection system can provide a suggestion to the operator based on initial measurement data. The operator can accept or change this suggestion. Depending on the operator's setting, either the smallest minimum value 24 of the derivative function 23 or the largest maximum value 25 of the derivative function 23 can be sought in the course of determining the edge distance value 26.

[0039] ​When the side shield 8 is positioned in the desired position relative to the edge 28 and the sensor unit 11 detects the edge, the operator can save the edge distance value 26 determined in this case as a target value. If the edge distance value 26 deviates from the target value, for example due to a steering movement of the road paver or due to the course of the edge, a deviation, for example a difference between the target value and the edge distance value 26, can occur. The respective extension 13 can be controlled in such a way that the deviation is compensated.

[0040] When the edge definition is less clear, the determination of the edge distance value 26 can result in alternating edge distance values 26, as described above. By inertia of the adjusting behavior of the screed 3, in particular of the extension member 13, it is possible to reduce the unnecessary consequences of such influences. If the consequences of the above-mentioned influences are to be further reduced, the course of the edge distance value 26 can be damped and smoothed by a suitable filter, for example a low-pass filter.

[0041] In addition, it can happen that objects in the surface 19 to be scanned occur which lead to the detection of unsuitable edge distance values 26, for example because the objects cause a higher slope in the smoothed function 22. In order to reduce the consequences of such objects, a plausibility check of the edge distance value can be carried out before the extension 13 is set into consideration. For example, a plausibility window can be defined around the target value by the unit for data processing. If the edge distance value 26 is within the plausibility window, the calculated difference between the target value and the edge distance value 26 can be taken into account when setting the extension 13. If the edge distance value 26 is outside the plausibility window, it can be assumed that the difference between the target value and the edge distance value 26 is 0, so that the edge distance value 26 that is judged to be implausible can be ignored when setting the extension 13.

Claims

1. An edge detection system (10) for a road paver (1), characterized in that, The edge detection system (10) includes: Sensor unit (11), the sensor unit (11) comprising: The transmitting module is configured to emit a sequence of laser pulses (16) in multiple directions (17), such that the sequence of laser pulses (16) is reflected at multiple locations (18) on the surface to be scanned (19). A detection module, configured to detect the reflection of the laser pulse sequence (16), and A signal generation module is configured to generate a polar coordinate signal representing polar coordinates based on the detected reflections, wherein the polar coordinates include distance and a related angle; A conversion unit configured to convert the polar coordinate signal into a Cartesian coordinate signal representing Cartesian coordinates; and, The first determining unit is configured to determine the position of the edge (28) in the surface to be scanned (19) relative to the Cartesian coordinate system (20) based on the Cartesian coordinate signal.

2. The edge detection system according to claim 1, characterized in that, The edge detection system (10) further includes a smoothing unit configured to determine a smoothed function (22) based on the Cartesian coordinate signal.

3. The edge detection system according to claim 2, characterized in that, The edge detection system (10) also includes a differentiating unit configured to differentiate the smoothed function (22) and determine the derivative function (23).

4. The edge detection system according to claim 3, characterized in that, The edge detection system (10) further includes a second determining unit configured to determine the minimum minimum value (24) and / or the maximum maximum value (25) of the derivative function (23).

5. The edge detection system according to claim 4, characterized in that, The edge detection system (10) further includes a third determining unit configured to determine an edge distance value (26) based on the derivative function (23) at the minimum minimum value (24) and / or the maximum maximum value (25), the edge distance value (26) representing the edge distance (27) between the edge (28) in the surface (19) to be scanned and the sensor unit (11).

6. The edge detection system according to any one of claims 1 to 5, characterized in that, The edge detection system (10) further includes a second sensor unit (14) and a sensor identification unit, the sensor identification unit being configured to distinguish the sensor unit (11) and the second sensor unit (14) based on the IP addresses of the sensor unit (11) and the second sensor unit (14).

7. An ironing board (3), characterized in that, It is used in a road paver (1), wherein the screed (3) includes an edge detection system (10) according to any one of claims 1 to 6.

8. The ironing board according to claim 7, characterized in that, It also includes at least one extension (13), wherein the movement of the extension (13) can be controlled based on the output of the edge detection system (10).

9. The ironing board according to claim 8, characterized in that, The output of the edge detection system (10) is an output representing the edge distance value (26).

10. The ironing board according to claim 8, characterized in that, The edge detection system (10) also includes a width control device configured to control the movement of the extension (13) based on a target value, which is an edge distance value (26) determined when the side shield (8) is positioned relative to the edge (28) at a desired location and the sensor unit (11) detects the edge.

11. The ironing board according to claim 10, characterized in that, The edge detection system (10) further includes a data processing unit configured to define a confidence window around the target value, wherein if the determined edge distance value (26) is within the confidence window, the determined edge distance value (26) is considered when moving the extension portion, and / or if the determined edge distance value (26) is outside the confidence window, the determined edge distance value (26) is ignored when moving the extension portion (13).

12. A road paver (1), characterized in that, Includes the edge detection system (10) according to any one of claims 1 to 6 or the ironing plate (3) according to any one of claims 7 to 11.

13. The road paver according to claim 12, characterized in that, The plane (29) of the road paver (1) and the direction of travel (7) form an angle (30), the angle (30) being greater than 0° and / or less than 180°.

14. The road paver according to claim 13, characterized in that, The angle (30) is greater than 75° and / or less than 105°.

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