STORING THE COURSE OF A PAVING EDGE TO CONTROL A LATERAL EXTENSION POSITION OF A PAVING SCREED OF A ROAD PAVER

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims foreign priority benefits under 35 U.S.C. § 119(a)-(d) to European patent application number 24218612.0, filed Dec. 10, 2024, which is incorporated by reference in its entirety.

TECHNICAL FIELD

The disclosure relates to a road paver and operation of a road paver. In particular, the disclosure relates to a road paver with a laterally extendable paving screed and to adjusting a lateral extension position of the paving screed.

BACKGROUND

From practice, road pavers are known in which a paving width is variable during an ongoing paving operation. For example, the road paver may comprise a paving screed with a rigid base screed to which an extension screed section is attached on each of both lateral sides. In order to change the paving width to one side, the extendable screed section provided on the respective side can be moved laterally in relation to the base screed. The extension positions of the extendable screed section can be adjusted, for example, by an operator via an external control station provided on the paving screed.

EP 3 524 731 B1 describes a road paver with an edge follower. If a roadway is to be constructed in several adjacent lanes, the edge follower can align the paving screed with the edge of an already completed lane so that there is no gap or overlap between the already completed lane and the lane currently being paved. The edge follower comprises at least one sensor which detects the edge ahead of the paving screed with respect to the direction of travel. By knowing the mounting position of the edge follower at the road paver and the driving speed of the road paver, a control device determines when the detected position of the edge will be reached by the following paving screed. Alignment of the paving screed with the detected edge is delayed after detecting the current edge position depending on the driving speed, with the delay being lower for a higher driving speed than for a relatively lower driving speed. In addition to taking the driving speed into account for the alignment of the paving screed, other operating parameters can also be used, such as a steering setting.

SUMMARY

It is an object of the disclosure to indicate an improved way of adjusting a side extension position of the paving screed of a road paver when paving a strip of pavement along a paving edge.

This object is achieved by a method for operating a road paver according to the disclosure, a road paver according to disclosure, and use of a data register according to the disclosure.

According to an aspect of the disclosure, a method for operating a road paver with a laterally extendable paving screed is provided. A paving run along a paving path is performed with the road paver. The paving path extends along a paving edge. During the paving run, an edge sensor attached to the road paver detects the paving edge at a position located ahead of a rear edge of the paving screed with respect to the paving direction. During the paving run, data is stored based on the detection of the paving edge. The data can be used during the paving run to reconstruct a course of the paving edge in a current paver-fixed coordinate system. On the basis of the stored data, a lateral extension position of the paving screed is adjusted during the paving run to a desired lateral distance between the rear edge of the paving screed and the paving edge.

The paving edge can be a physical edge that extends along the paving path. For example, the paving edge can be formed by at least one structural element that represents a course of a pavement strip to be installed. The at least one structural element can comprise, for example, a curb or a water drain. The paving edge can be a milled edge created by at least partially milling off an old road surface. The paving edge can be a lateral end edge of a paving strip installed in a previous work step, whereby another paving strip is installed adjacent to the paving edge during the paving run with the road paver.

A lateral outer edge of a pavement strip installed during the paving run can be determined by a course of the lateral position of the rear edge of the paving screed during the paving run. Thus, by adjusting the lateral distance between the rear edge of the paving screed and the paving edge, a desired lateral distance between the installed pavement strip and the paving edge can be achieved.

The desired lateral distance between the rear edge of the paving screed and the paving edge can be at least essentially 0, so that the strip laid during the paving run is laid right up to the paving edge. In particular, the strip laid during the paving run can at least partially fill up the paving edge. However, the desired lateral distance between the rear edge of the paving screed and the paving edge can also be greater than 0, so that the paving strip is laid at a lateral distance from the paving edge. The desired lateral distance between the rear edge of the paving screed and the paving edge can vary along the paving path according to planning data.

Since the paving edge is detected ahead of the rear edge of the paving screed with respect to the paving direction, the method can, in particular, also be used when it is difficult or impossible to detect the paving edge in the area of the rear edge of the paving screed, for example, when the paving strip is installed close to the paving edge and the paving strip, thus, at least partially covers the paving edge in the area of the rear edge of the paving screed or partially or completely fills a height difference present at the paving edge.

The course of the paving edge is detected ahead of the rear edge of the paving screed with respect to the paving direction and is stored so that, when the rear edge of the paving screed reaches the respective position along the paving direction, the lateral extension position can be adjusted on the basis of the previously stored data. With the method according to the disclosure, the rear edge of the paving screed can be aligned relative to the paving edge with a high degree of accuracy, even if the road paver has changed its travel speed or direction of travel between the time at which a point on the paving edge was measured and the time at which the rear edge of the paving screed is aligned relative to the point of the paving edge. With the method according to the disclosure, the rear edge of the paving screed can be aligned relative to the paving edge, in particular with high accuracy, even if the width of the pavement strip to be paved, as defined by the paving edge, changes along the paving direction.

Since the course of the paving edge can be reconstructed from the stored data during the paving run in the current paver-fixed coordinate system, adjusting the lateral extension position of the paving screed is facilitated. In particular, complicated calculations in a global coordinate system can be reduced or avoided.

The data can be stored by a controller. Adjusting the lateral extension position on the basis of the stored data can be done by the controller. The controller can be a controller of the road paver. The controller can be provided on the road paver or at the road paver. Alternatively, the controller can be provided externally to the road paver and be connected to the road paver via a data connection.

Storing the data may comprise storing the data in a data storage. The data storage may be a data storage of the road paver. The data storage may be provided on or at the road paver. Alternatively, the data storage may be provided outside the road paver and be connected to the road paver, in particular to the controller of the road paver, via a data connection. For example, the data storage may be provided as cloud storage.

Detecting the paving edge may include measuring a distance between the edge sensor and the paving edge. Detecting the paving edge may correspond to measuring a distance between the edge sensor and the paving edge. The distance between the edge sensor and the paving edge may be a distance along a direction fixed in relation to the road paver. The distance between the edge sensor and the paving edge may be a distance along a lateral direction perpendicular to the paving direction.

The paving edge can be detected repeatedly during the paving run, in particular periodically. The paving edge can be detected during the paving run at a frequency of more than 0.05 Hz, or more than 0.1 Hz, or more than 0.5 Hz, or more than 1 Hz, for example. The paving edge can be detected during the paving run at a frequency of less than 50 Hz, or less than 20 Hz, or less than 10 Hz, or less than 1 Hz, for example. The paving edge can be detected during the paving run at a frequency between 0.05 Hz and 100 Hz, or between 0.1 Hz and 50 Hz, or between 0.5 Hz and 50 Hz, for example.

The data can be stored repeatedly during the paving run, in particular periodically. The data can be stored at the same frequency as the paving edge is detected.

Storing the data can include storing positions of points of the paving edge detected by the edge sensor.

The positions of points of the paving edge detected by the edge sensor can be stored in the form of two-dimensional position vector, respectively. Storing in the form of a two-dimensional position vector makes it easier to reconstruct the course of the paving edge in a current paver-fixed coordinate system, especially when compared to storing a simple distance value. The two-dimensional position vector can define a point in a plane spanned by the direction of travel of the road paver and a lateral direction perpendicular to the direction of travel of the road paver. It is not necessary to determine a height level of the paving edge or to store a height coordinate of the paving edge. The two-dimensional position vector can be stored, for example, in Cartesian coordinates or in polar coordinates.

Storing the data may include storing positions of points of the paving edge detected by the edge sensor as coordinates in a paver-fixed coordinate system. Storing the positions of points of the paving edge in a paver-fixed coordinate system can facilitate reconstruction of the paving edge during the paving run in a current paver-fixed coordinate system. The paver-fixed coordinate system in which the positions of the points of the paving edge are stored can be a paver-fixed coordinate system that is the current paver-fixed coordinate system at the time of detection of the respective position. In particular, storing the data may include initially storing positions of points of the paving edge detected by the edge sensor as coordinates in a paver-fixed coordinate system that is the current paver-fixed coordinate system at the time of detection of the respective position.

Storing the data may include updating the stored coordinates during the paving run by converting the stored coordinates into a paver-fixed coordinate system that is the current paver-fixed coordinate system after the paver has moved on. The conversion of the stored coordinates into a paver-fixed coordinate system that is the current paver-fixed coordinate system may be repeated during the paving run, in particular periodically. In particular, whenever a newly detected position of a point of the paving edge is stored, the coordinates of previously detected points of the paving edge that have already been stored can be converted into the currently updated paver-fixed coordinate system. All stored coordinates of detected points of the paving edge can always be converted into the current paver-fixed coordinate system.

During the paving run, information about changes in orientation and location of the road paver can be determined and used to update the stored coordinates. The information about changes in orientation and location of the road paver can include information about translational movements of the road paver and information about rotational movements of the road paver. A change in the orientation and location of the road paver between the last detection of a position of the paving edge and the current detection of a position of the paving edge can be determined. On the basis of this information, all stored coordinates of points of the paving edge can be converted from the fixed coordinate system of the road paver that was current at the time of the last detection of a point of the paving edge to the now current fixed coordinate system of the road paver.

The information about changes in orientation and location of the road paver can be determined from rotational speeds of a left chain drive and of a right chain drive of the road paver, or from position data from at least one GNSS (Global Navigation Satellite System) receiver provided at the road paver. The at least one GNSS receiver provided at the road paver may comprise at least two GNSS receivers provided at the road paver. The GNSS receivers may be provided at known mounting points on the road paver. If at least two GNSS receivers are provided, both the determination of a translational movement and the determination of a rotational movement of the road paver may be facilitated.

During the paving run, at least the last 3, or at least the last 5, or at least the last 10, or at least the last 15 positions of points of the paving edge detected by the edge sensor can be stored in a retrievable manner. It is also conceivable that during the paving run, considerably more detected positions of points of the paving edge are stored in a retrievable manner, for example at least the last 50, or at least the last 100, or at least the last 150, or at least the last 200 positions of points of the paving edge detected by the edge sensor. Also, all positions of points of the paving edge detected during the course of the paving run so far can be stored in a retrievable manner.

Adjusting the lateral extension position may include selecting one of the stored positions of points of the paving edge and using it to determine a target value for a lateral extension position of the paving screed. For example, the stored position that was stored first among those stored positions of points of the paving edge that are located at the level of the rear edge of the paving screed with respect to the current paving direction or further to the rear can be selected. Alternatively, for example, the stored position that is closest to the current position of the rear edge of the paving screed with respect to the current paving direction can be selected.

The target value for the lateral extension position of the paving screed can be determined based on the position of the selected point of the paving edge and the desired lateral distance between the rear edge of the paving screed and the paving edge.

Adjusting the lateral extension position may involve adjusting the lateral extension position of the paving screed to the determined target value. The lateral extension position may be an extension position relative to the road paver. The lateral extension position may, for example, be defined by the distance by which the paving screed is extended laterally from a maximally retracted position.

According to a further aspect of the disclosure, a road paver is provided. The road paver comprises a laterally extendable paving screed, an edge sensor, a controller, and a data storage. The edge sensor is configured to detect, during a paving run, a paving edge at a position located ahead of a rear edge of the paving screed with respect to the paving direction. The controller is configured to store data in the data storage during the paving run based on the detection of the paving edge, from which a course of the paving edge can be reconstructed in a current paver-fixed coordinate system during the paving run. The controller is configured to adjust a lateral extension position of the paving screed on the basis of the stored data during the paving run to a desired lateral distance between the rear edge of the paving screed and the paving edge.

The road paver may comprise a towing vehicle. The towing vehicle may be configured to pull the paving screed behind it in the direction of paving. The paving screed may be attached to the towing vehicle in an articulated manner by means of drawbars.

The paving screed may comprise a base screed. The base screed may have a fixed width in a lateral direction perpendicular to the paving direction. The paving screed may comprise at least one extension part which can be extended laterally relative to the base screed in order to increase the paving width. The at least one extension part may comprise a left extension part, or a right extension part, or a left extension part and a right extension part. A drive may be assigned to the at least one extension part. The controller may be configured to control the drive to extend or retract the associated extension part laterally, in particular to move the associated extension part to a target value for a lateral extension position of the paving screed. An extension part may be provided on both sides of the base screed, i.e., a left extension part and a right extension part. Alternatively, an extension section may be provided on only one side, i.e., only a right extension section or a left extension section. If extension parts are provided on both sides of the base screed, each extension parts may be assigned a drive of its own so that each extension part can be controlled separately.

The road paver may comprise a material hopper for receiving paving material. The material hopper may be provided at the front of the road paver with respect to the paving direction. The road paver may comprise a conveyor device configured to convey paving material from the material hopper against the direction of paving travel and to feed it to the paving screed for compaction.

The edge sensor may be configured to detect a distance along a lateral direction perpendicular to the paving direction between a position of the edge sensor at the road paver and the paving edge.

The edge sensor can be designed, for example, as a lidar (light detection and ranging) sensor, a radar (radio detection and ranging) sensor, or an ultrasonic sensor.

The data storage may comprise a data register. The controller may be configured to store positions of the paving edge detected sequentially by the edge sensor during the paving run in the form of coordinates in the data register. The data register can optionally have a fixed number of memory locations for the coordinates, so that when coordinates of a newly detected point of the paving edge are added, the coordinates of a point of the paving edge that was detected the longest time ago are dropped from the register or deleted.

The data storage can be designed as a hard disk, flash memory, or SSD (solid state drive), for example.

The controller can be configured to initially store the positions of points of the paving edge detected by the edge sensor in the data storage as coordinates in a paver-fixed coordinate system that is the current paver-fixed coordinate system at the time of detection of the respective position. The positions of points of the paving edge detected by the edge sensor can be stored in particular in the form of a two-dimensional location vector each.

The controller can be configured to periodically update the stored coordinates during the paving run by converting them into a paver-fixed coordinate system that is the current paver-fixed coordinate system after the paver has moved on. During the paving run, the controller can determine information about changes in orientation and location of the road paver and use this information to update the stored coordinates. The controller can be configured to determine the information about changes in position and location of the road paver from the rotational speeds of a left chain drive and of a right chain drive of the road paver, or from position data from at least one GNSS (Global Navigation Satellite System) receiver provided at the road paver.

The controller can determine the orientation change and the position change of the road paver between the last detection of a position of the paving edge and the current detection of a position of the paving edge. On the basis of this information, the controller can convert all stored coordinates of points of the paving edge from the stationary coordinate system of the road paver that was current at the time of the last detection of a point of the paving edge to the now current stationary coordinate system of the road paver.

According to a further aspect of the disclosure, a use of a data register is provided. The data register stores positions of points of a paving edge, which were sequentially detected ahead of a rear edge of the paving screed of the road paver during a paving run of a road paver. The data register is used to adjust a lateral extension position of the paving screed to a desired lateral distance between the rear edge of the paving screed and the paving edge.

Features, explanations, and advantages described in relation to one of the aspects or embodiments described herein are transferable to or combinable with the other aspects or embodiments. The described road paver may be suitable, designed, and/or configured to perform the described method or to perform the described use. The described method or the described use may be performed or carried out on the basis of the described road paver. The method may include the use. The use may include the method.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments are explained in more detail below with reference to the figures.

FIG. 1 shows a schematic side view of a road paver according to an embodiment;

FIG. 2 shows a schematic top view of the road paver according to the embodiment during a paving run; and

FIG. 3 shows a schematic representation of a data register of the data storage according to an embodiment.

DETAILED DESCRIPTION

FIG. 1 shows a road paver 1 according to an embodiment. The road paver 1 comprises a towing vehicle 3 and a paving screed 7 for compacting paving material towed behind the towing vehicle 3 with respect to a paving direction 5. At the front with respect to the paving direction 5, the road paver 1 comprises a material hopper 9 for receiving paving material. Paving material from the material hopper 9 is fed to the paving screed 7 during a paving run and compacted by the paving screed 7. The road paver 1 comprises a main operating station 11, which provides a place for an operator and has operating devices 13 for controlling various functions of the road paver 1.

FIG. 2 shows a top view of the road paver 1 during a paving run while laying a pavement strip 15. The paving screed 7 comprises a main screed 17 and, on both lateral sides of the main screed 17, an extension part 19, i.e., a left extension part 19 as seen along the paving direction 5 and a right extension part 19 as seen along the paving direction 5. The extension parts 19 can be extended or retracted relative to the main screed 17 along a lateral direction 25 perpendicular to the paving direction 5 by means of a drive 23 assigned to the respective extension part 19 in order to change the paving width on the respective side. The drives 23 can each comprise a motor 27 and a position sensor 31. The motor 27 can be designed as a hydraulic motor or an electric motor, for example. The position sensor 31 can determine the current extension position of the respective extension part 19 of the paving screed 7.

A controller 35 of the road paver 1 can transmit a respective target value for a lateral extension position of the associated extension part 19 to each of the drives 23. Based on the current extension position of the extension part 19 determined by the sensor 31, the drive 23 can adjust the extension position of the respective extension part 19 to the target value by means of the motor 27.

In the illustrated embodiment, the paving strip 15 is installed between installation edges 37 opposing each other along the lateral direction 25. During the paving run, the lateral extension positions of the paving screed 7 are continuously adjusted on both sides in order to adjust a desired lateral distance between the rear edge 41 of the paving screed 7 and the respective paving edge 37. The desired lateral distance can be the same on both sides or different on the left side than on the right side. In the illustrated embodiment, the desired lateral distance 43 on the left side with respect to the paving direction 5 is at least substantially 0, so that the paving strip 15 is laid up to the left paving edge 37. In the illustrated embodiment, the desired lateral distance 43 on the right side is greater than 0, for example a value greater than 2 cm, or a value greater than 5 cm, or a value greater than 10 cm, so that the covering strip 15 does not extend all the way to the paving edge 43 on the right side.

A respective edge sensor 47 is provided on each of the two lateral sides in front of the rear edge 41 of the paving screed 7. The edge sensor 47 can, for example, be attached to a side plate 51 of the extension part 19 located on the respective side. The edge sensor 47 detects a distance between the edge sensor 47 and the associated paving edge 37 along the lateral direction 25.

During the paving run, the paving edges 37 are periodically detected by the respective edge sensor 47 by measuring the distance between the edge sensor 47 along the lateral direction 25 and the respective paving edge 37. The positions of points of the paving edges 37 detected in this way are stored in a data register 57 of a data storage 58 of the road paver 1 and are used to control a lateral extension position of the respective extension part 19. For the sake of clarity, only the procedure relating to one of the two extension parts 19 is described below. The same procedure can be followed for the other extension part 19. Alternatively, the other extension part can be controlled in a different way, for example manually by an operator. Also, only one extension part 19 may be provided.

Preferably, the detected positions of points of the paving edge 37 are each stored in the form of a two-dimensional position vector in a paver-fixed coordinate system. In the illustrated embodiment, the paver-fixed coordinate system is selected such that its origin is located at a theoretical pivot point 59 of the tractor 3, and such that the paver-fixed coordinate system is defined by an x-axis pointing along the paving direction 5 and a y-axis pointing to the left along the lateral direction 25, whereby the two axes x and y are perpendicular to each other. However, the paver-fixed coordinate system can also be defined differently.

In the illustrated embodiment, the following position vector results for a position of a point of the right paving edge 37 detected by the right edge sensor 47 at a time index t: (xt, yt)=(−a, −(b_t+m_t)). Here, a is the distance between the theoretical pivot point 59 of the tractor 3 and the mounting position of the right edge sensor 47 parallel to the paving direction 5, thus a known fixed value. b_t is the current distance between the mounting position of the right edge sensor 47 and the theoretical pivot point 59 of the tractor 3 parallel to the lateral direction 25 and is known from the distance sensor 31 and the known mounting position of the edge sensor 47 on the side plate 51. m the distance that is currently measured by the right edge sensor 47 between the right edge sensor 47 and the right paving edge 37 along the lateral direction25.

FIG. 3 shows a schematic representation of the data register 57. The first column 56 shows the time index t to which the stored coordinates shown in the respective row are assigned. For example, the time index 1 may represent the last measurement taken, and the subsequent time indexes may represent measurement values further back in time. Column 61 contains the x-coordinate of the point of the right paving edge 37 detected at the respective time index in the paver-fixed coordinate system. Column 63 contains the y-coordinate of the point of the right paving edge 37 detected at the respective time index in the paver-fixed coordinate system.

When coordinates of a point of the paving edge 37 are detected at a current time index and are stored in the data register 57, they are stored in the currently valid paver-fixed coordinate system. In addition, the coordinates already present in the data register 57 are converted to the current paver-fixed coordinate system so that all information in the data register 57 is always available in the current paver-fixed coordinate system.

In order to convert the coordinates stored in the data register 57 into the current paver-fixed coordinate system, information about changes in the orientation and location of the road paver 1 is determined during the paving run and used to update the stored coordinates. In particular, an average travel speed v of the road paver 1 since the last time index and an average rotation rate of the road paver 1 since the last time index are determined and used to update the stored coordinates.

In the illustrated embodiment, the controller 35 determines the information about orientation and location changes of the road paver 1, in particular the average travel speed v of the road paver 1 since the last time index and the average rotation rate of the road paver 1 since the last time index, based on outputs from two GNSS receivers 60 attached to (different) known positions of the road paver 1. Alternatively, the controller 35 can determine the information about changes in the orientation and location of the road paver 1, in particular the average travel speed v of the road paver 1 since the last time index and the average rotation rate of the road paver 1 since the last time index, from the rotational speeds of a left chain drive and a right chain drive of the road paver 1. To increase accuracy, information determined based on the GNSS receivers 60 and information determined based on the rotational speeds of the chain drives can also be merged, for example, using a Kalman filter.

At the time of a current detection of a position of the paving edge 37, the coordinate pairs stored in the data register 57 are represented in the paver-fixed coordinate system that was current at the time of the last preceding detection of a position of the paving edge 37, but is now outdated. The following formulas are used to convert the stored coordinates from the outdated paver-fixed coordinate system to the current paver-fixed coordinate system:

x_t,new=x_t,old*cos( *Δt)+y_t,old*sin( *Δt)−v*Δt

y_t,new=y_t,old*cos( *Δt)−x_t,old*sin( *Δt)

• • (x_t,old, y_t,old): Coordinate pair in outdated paver-fixed coordinate system
  • (x_t,new, y_t,new): Coordinate pair in outdated paver-fixed coordinate system
  • Δt: Time interval between the preceding, last detection of a position of the paving edge 37 and the current detection of a position of the paving edge 37
  • : Average rotation rate of the road paver 1 about the theoretical pivot point 59 between the preceding, last detection of a position of the paving edge 37 and the current detection of a position of the paving edge 37
  • v: Average travel speed of the road paver 1 between the preceding, last detection of a position of the paving edge 37 and the current detection of a position of the paving edge 37

Due to being periodically converted, the stored coordinate pairs are always available in the current paver-fixed coordinate system during the paving run and can therefore be used directly to adjust the extension position of the extension part 19.

During the paving run, the controller 35 periodically adjusts the extension positions of the extension section 19 of the paving screed 7 based on the data stored in the data register 57 and thus based on the course of the paving edge 37. The controller 35 selects a coordinate set (x_t, y_t,) from the data register 57 which indicates a situation at the rear edge 41 of the paving screed 7 at the current time. For example, the controller 35 can select the coordinate set that has the smallest time index from those stored coordinate sets that satisfy the condition x_t≤−c in the current coordinate system, where c is the fixed distance of the rear edge 41 of the screed from the theoretical pivot point 59 of the tractor 3 parallel to the paving direction 5.

The selected coordinate set is then used to control the extension position of the extension part 19 so that the side plate 51 of the extension part 19 is adjusted to the desired lateral distance 43 between the rear edge 41 of the paving screed 7 and the paving edge 37 by suitably actuating the drive 23.

As one skilled in the art would understand, the controller 35, as well an any other controller, sensor(s), device, or the like described herein may individually, collectively, or in any combination comprise appropriate circuitry, such as one or more appropriately programmed processors (e.g., one or more microprocessors including central processing units (CPU)) and associated memory (e.g., data storage 58) which may include stored operating system software and/or application software executable by the processor(s) for controlling operation thereof and/or for performing the particular algorithms represented by the various functions and/or operations described herein, including interaction and/or cooperation between any such controller, sensor(s), device, or the like. One or more of such processors, as well as other circuitry and/or hardware, may be included in a single component (e.g., an ASIC (Application-Specific Integrated Circuit)), or several processors and various circuitry and/or hardware may be distributed among several separate components, whether individually packaged or assembled into a SoC (System-on-a-Chip).