The invention relates to a method and a system for determining the position of a formwork fitted to at least one existing formwork.
In this context, a formwork is a single element, which is usually flat on at least one side, for producing a hollow mould for casting concrete parts. Such an element usually comprises a formwork plate or a formwork panel and can optionally comprise a frame. The formwork panel is regularly made of wood, such as plywood or solid wood for example, and can optionally be coated or sealed. The invention is applicable to any type of formwork, e.g., wall formworks and/or ceiling formworks and/or climbing formworks.
Such formworks are usually reused multiple times, often also on the same construction site. In addition, depending on the requirements of the concrete parts to be cast, formworks of different sizes and thicknesses are used.
In order to make optimal use of the existing formworks, it is important to track which formwork is used when and where. On the basis of this information and/or a specified forming time or a defined construction process, a form removal time for each formwork can be determined individually. Thereby, the information is available concerning which formwork with which dimensions along with where and when it is free for reuse. This allows an overview of the existing formworks and an optimization of the total necessary formworks (i.e., the number) as well as the transport routes of the individual formworks. Furthermore, it is also favourable to track the positions of the formworks during interim storage. From this, conclusions can be drawn for waste management, logistics and/or construction site operations, and it is possible to determine where there is currently space for setting up a formwork.
For the determining the position or locating the formwork, an accuracy is required, which can be achieved, for example, with UWB technology (ultra-wideband). Signals with a bandwidth of at least 500 MHz are used, and a relatively low transmission power can be used in order not to interfere with frequency ranges that are already allocated (e.g., 0.5 mW/−41.3 dBm/MHz). These frequency ranges allow centimetre-accurate indoor localizations and integrated data communication. With this technology, receivers (or “anchors”) for locating signals are positioned at a plurality of reference points around a desired area. The receivers receive locating signals from transmitters (e.g., “tags”, “sensors” or “transmitters”) and forward the received information (e.g., time stamp, signal strength, data content) to a central unit (or “server”). This forwarding can take place in real-time (RT) or near real-time (NRT). In this case, this is referred to as a real-time locating system (RTLS). The position determination is based on the determination of the distances of the transmitter to a plurality of receivers; specifically, the transit time between the transmitter and at least three receivers is determined, and, on the basis of this information provided by the receivers, the position of the transmitter is determined together with the known positions of the receivers by means of trilateration. For example, the transmitters can be battery-operated. They essentially transmit at least one identification (ID) and one timestamp (“timestamp”) to the receiver. An exemplary application of this positioning technology for the dynamic position determination of persons, e.g., on a playing field, is described in WO 2013/167702 A1.
However, for the application of the position determination of formworks on a construction site, the technology explained above has the disadvantage that a line of sight (LoS) between the transmitter and at least three receivers is required. A line of sight can be understood not only as a direct optical line of sight between receiver and transmitter, but also as an interruption-free or low-interruption transmission of electromagnetic signals, data, etc. Due to the essentially plate-shaped geometry of formworks and their opposite/mirrored arrangement during use, the simultaneous use of a plurality of formworks (e.g., more than ten) almost inevitably leads to interruptions of these lines of sight and signal disturbances, in particular, if the receivers are to be located outside the construction site (for example, at the edge or above). In principle, this problem could be solved by arranging three receivers in each room to be built. However, the associated effort (equipment costs and setup effort) makes this solution impractical.
Another purpose is pursued by EP 3 351 699 A1. The system and method shown in it is used to automate a crane control system during the construction of a building made of prefabricated wall elements. The target position of a new wall element is determined based on measurements of the existing building and the new wall element. The actual position of the new wall element is determined and continuously monitored with GNSS receivers on the wall element itself or on a crane gripper or with measuring devices and corresponding reflectors on the new wall element.
The US 2005/0107934 A1 only generally concerns a position determination on a construction site. The positions of different monitored units are determined by GNSS.
It is an object of the invention to eliminate or at least reduce at least individual disadvantages of the prior art.
The invention provides for a method of the type mentioned above, comprising:
sending a locating signal from the fitted formwork (i.e., from a tag or transmitter of this formwork);
receiving the transmitted locating signal with a receiver at at least one reference point;
determining a distance between the fitted formwork and at least one reference point based on the received locating signal;
determining a fitting position of the fitted formwork on at least one existing formwork compatible with the determined distance (wherein the position(s) of at least one existing formwork is/are known); and
saving the determined fitting position as the position of the fitted formwork.
In addition, the invention provides for a system of the aforementioned type, comprising:
a fitted formwork with a transmitter for a locating signal,
at least one reference point with a receiver for a locating signal,
a distance detection unit set up to determine a distance between the fitted formwork and at least one reference point based on a locating signal sent by the transmitter and received by the receiver;
a position database with stored positions of at least one existing formwork; and
an adjustment unit set up to determine a distance compatible with a distance determined by the distance determination unit of the fitted formwork on an existing formwork and to store the determined fitting positions in the position database as the position of the fitted formwork.
When determining the distance between the fitted formwork and the reference point, the distance between the transmitter or tag on the formwork and one or a plurality of receivers or anchors is specifically determined. Naturally, this determination is not based exclusively on the received locating signal, but also takes into account, for example, the position of the receiver and the time of receipt of the locating signal. Depending on the circumstances, one or a plurality or all fitting positions of the fitted formwork on the at least one existing formwork can be determined. Determining a fitting position requires knowledge of the geometry of the two formworks. In the simplest case, a uniform, predetermined geometry of all formworks can be assumed. If exactly one compatible fitting position has been determined, this fitting position is stored as the position of the fitted formwork. Otherwise, a selection can be made based on a sequence of fitting positions, for example, based on an associated inaccuracy or an associated probability.
Determining the fitting position can comprise, for example:
determining all possible fitting positions of the fitted formwork on the at least one existing formwork;
determining the respective associated distance of the determined possible fitting positions to the at least one reference point;
determining those fitting positions as compatible with the determined distance whose associated distance is within a tolerance range around the determined distance. As a tolerance range, in particular, a distance range can be used, the width of which essentially corresponds to the inaccuracy of the positioning, e.g., with a width between 5 cm and 30 cm or of about 10 cm or of about 20 cm.
As an alternative to determining all fitting positions of the fitted formwork on the at least one existing formwork, it is also conceivable that only the fitting positions within the tolerance range of the determined distance are determined. Especially with a very large number of existing formworks, methods can be simplified and accelerated with this method.
In addition, determining the fitting position can comprise: Limiting the possible fitting positions based on a local zone boundary. The local zone boundary forms a boundary condition for possible fitting positions. This means that only those fitting positions are possible in which the formwork is positioned within the locally limited area. The construction site size and position or generally the boundary or dimensions of the construction site can be used as such an area limit, for example. In this example, only such fitting positions would be considered in which the formwork remains on the construction site.
In this context, determining the fitting position may also comprise: Limiting the possible fitting positions on the basis of orientation information regarding the fitted formwork. The orientation information can be obtained, for example, by means of a magnetometer or a compass, each of which can be fixed to the fitted formwork. If orientation information is available, possible fitting positions in which the hypothetical orientation of the formwork differs from the actual situation determined on the basis of the orientation information can in principle (i.e., determined according to one of the above-mentioned methods) be discarded. A limit value or tolerance range can be used, which is based on the inaccuracy of the orientation information, for example a tolerance range of 10° for the horizontal orientation and a tolerance range of 20° for the vertical orientation.
The fitted formwork in the present system can optionally have an orientation sensor, wherein the orientation sensor is connected to the transmitter for the locating signal. As a result, the orientation information can be read from the orientation sensor and transmitted to the receiver via the transmitter. Sufficient information is then available on the receiver to determine both the orientation as well as—possibly depending on the orientation—the position of the fitted formwork.
In a further embodiment, the transmitter or tag of the fitted formwork can also comprise a 3D gyrometer (3D gyroscope), 3D magnetometer and/or a 3D accelerometer (acceleration sensor). Formworks are essentially supplied with certain widths and heights. Examples of such widths include 30 cm, 45 cm, 60 cm, 90 cm and 135 cm. Examples of such heights include 135 cm, 270 cm and 330 cm. On a construction site, it may well occur that two or a plurality of formworks are used to depict a different formwork height or width. For example, 45 cm wide and a 90 cm wide formwork could be combined to form a 135 cm wide formwork. In order to make this system usable for the application according to the invention, not only the two-dimensional orientation (magnetometer), but also the orientation in three-dimensional space can be determined. If a formwork is now rotated to depict the width as height and height as width, the three-dimensional orientation can be detected in order to be able to determine the fitting positions more precisely.
Such a orientation detection in three-dimensional space also offers the positive effect that a formwork lying horizontally or on a stack can also be detected. Horizontal formwork is basically equivalent to stationary, i.e., inactive formworks. As soon as a resting position is detected, it can be calculated and compared with the digital model whether the formwork is still in use or can be removed. If a flat horizontal formwork is detected, it can be set to inactive in the digital system. The position of the inactive formwork is also determined by the geometry data of the formwork. Since the exact position determination is not primarily important for horizontal formworks and horizontally lying formworks are visually easily detectable, an approximate position determination is sufficient, in particular, since flat horizontal formworks often comprise no visual contact due to their low position (Line of Sight; LoS) to the receivers, so that, from the point in time when there is contact with no receiver, a high probability can be associated with the formwork that it is in a resting position. In the case of delivered containers (e.g., formworks stacked on top of each other), the topmost formwork can be detected in a resting position. The horizontal formworks below can only be detected with difficulty or not at all, as the line of sight is interrupted by the horizontal formwork. The first formwork must therefore first be lifted off before the horizontal formwork can be detected. An indication of which formworks are also located below on the transmitter or tag of the top formwork lying horizontally. In addition, it would also be conceivable to attach a tag or transmitter to the pallet or container itself, on which information about the formworks is stored. This data can be processed upon delivery and from the time of visual contact to at least one receiver. When stacking the formworks, the formworks that are moved into a resting position can be detected in time. Thus, a probable stacking sequence can be detected and stored in the digital system.
In accordance with an exemplary embodiment of the disclosed method, a locating signal together with a geometry of the fitted formwork and/or with a orientation information from the fitted formwork can be transmitted to a receiver. A definition of the geometry of the formwork can be contained in the locating signal or a reference to one of a plurality of possible specified geometry definitions or an identification of the formwork, from which the geometry can be concluded and which, for example, is linked to a geometry definition.
Accordingly, in the disclosed system, the adjustment unit can be connected to a geometry database with stored formwork geometries of the fitted formwork and at least one existing formwork. The use of such a geometry database is useful if a plurality of different geometries are used.
If no orientation information is available or in order to avoid the transmission of errors in the position determination, the transmitter can be centred on the fitted formwork in the system disclosed here. This means that the transmitter for the locating signal is essentially arranged in the middle of a rear side (i.e., side facing away from the concrete or other building material when pouring) of the formwork and centred at least horizontally on the plane of this lateral surface.
Apart from that, the invention also generally relates to a method for determining the position of a fitted formwork, comprising:
determining the number of reference points with a direct line of sight (i.e., an interference-free or low-interference signal connection, see above) to the fitted formwork;
if the determined number of reference points is less than three or less than two, performing the method according to one of the variants described above.
The conditional application of the method described above allows a differentiation and combination with other, possibly more accurate positioning methods. If such are available, a computationally potentially comparatively more complex and/or inaccurate determination according to the methods presented here can be dispensed with.
If the determined number of reference points is at least three, the position of the fitted formwork can be determined based on the distances to the at least three reference points and associated with a probability of one. As soon as at least three reference points have a line of sight in the sense of an interference-free or low-interference signal connection to the fitted formwork, the position of this formwork can be geometrically determined unambiguously, regardless of the position of other formworks. A position determined in this way can be associated with probability of one to express that no assumptions about the identity, geometry and/or position of the formwork were required to determine the position.
In this context, a reduced probability of less than one can be associated with the position of the fitted formwork determined by one of the methods described above (i.e., on the basis of possible fitting positions), wherein the probability associated with the at least one existing formwork to which the fitted formwork is fitted is taken into account. This allows the uncertainty of the position determined on the basis of a plurality of assumptions to be expressed in a quantitative parameter. Basically, the probability decreases with the number of assumptions made. For example, the probability associated with the existing formwork can be taken into account as a multiplication factor for the new probability. The resulting probability of the position of the fitted formwork can be taken into account when assessing compatibility. For example, if a lower probability limit is exceeded, a warning can be output or a positioning at the relevant position can be discarded (i.e., not stored).
The reduced probability can optionally be determined depending on a deviation of the determined distance from the distance corresponding to the stored fitting position. As a result, the parameter of probability can reflect how great the influence of the assumptions made (fitting position) was compared to the measurement (distance). A larger deviation of the distances thus corresponds to a lower probability. According to a further embodiment variant, the method can be carried out on the basis of a stored installation sequence of a plurality of formworks and the respectively determined positions and/or distances, wherein, in the case of a plurality of possible fitting positions for a fitted formwork, the probability of the possible fitting positions is evaluated on the basis of other chronologically subsequently erected formworks and that of the possible fitting positions is determined as the position of the fitted formwork to which the greatest probability is associated. In this way, after erecting a plurality of formworks, the collected position information of all distance measurements can be combined and can be corrected on this basis the positions of all formworks.
Optionally, determining the fitting position can comprise:
determining a connection geometry for at least two positioning options;
determining the fitting position as part of the position determination of a subsequent formwork, wherein the position of the subsequent formwork is determined at a fitting position compatible with the connection geometry.
In this context, for example, certain forms or special forms can be represented in a simplified way in the digital system. For example, a corner element can have the geometry data of a square in a simplified way. The connection surfaces are decisive for the simplified geometry since the connection surfaces should always be at the edges of the simplified geometry. After other formworks have been placed, the probability of the precise position and orientation of the formwork can be determined more precisely. For example, an arc element could be represented as a square. The position of this simplified square could now be determined. However, there would still be uncertainty as to whether the formwork element was erected correctly. It would be possible, for example, that the arc element was placed mirrored or twisted in the simplified geometry field (square). To prevent this uncertainty, the exact alignment could be displayed using a 3D magnetometer. Other shapes are also possible for such simplified geometries or connection geometries. Examples include rhomboids, parallelograms, deltoids, etc. In addition, a connection geometry can also be three-dimensional. Examples of this are cuboids, wherein the lateral surfaces of such a cuboid of a connection geometry can be congruent with the connection surfaces of a fitted (position-determining) formwork. Basically, a connection geometry is to be seen as a placeholder (block) for a not yet 100% defined position and orientation of a formwork. Furthermore, it would also be conceivable to create a tolerance field via a formwork geometry. This could be represented by a formwork geometry minimum, which has the minimum tolerance geometries, and a formwork geometry maximum, which has the maximum tolerance geometries. A tolerance field would thus form between these two tolerance geometries. The tolerance field represents an uncertainty of the exact position of the spatial boundary surfaces (and thus also of the connection surfaces) at each point of the formwork. Geometrically, the tolerance field corresponds to a shell with a defined thickness (distance between minimum tolerance geometry and maximum tolerance geometry; does not have to be the same everywhere) at which the actual boundary surface is expected. The thickness is inversely proportional to the accuracy with which the position and geometry of the boundary surface is known.
There may also be a plurality of transmitters, tags and/or sensors attached to a formwork. This can be particularly preferred to improve the locating accuracy, since at least two feedbacks can be detected per formwork to be located. Furthermore, the acquisition of at least two transmitters can also provide information about the position of the formwork and serve as a comparison for the recorded position information by the position sensors.
In the case of square formworks, the transmitters, tags and/or sensors are preferably mounted diagonally compared to the areas of the formwork near the corner. This has the advantage that regardless of the rotation of the formwork, a transmitter, tag and/or sensor is always located in an upper part of the formwork.
In addition, it should be mentioned that the connection surfaces, fitting positions, or fitting surfaces of formworks can represent any circumferential surfaces. For example, in those formwork systems that are designed in such a way that formworks can be concreted standing, but also turned. An example is a standing formwork that has been rotated by 90 degrees. The invention is explained below on the basis of particularly preferred exemplary embodiments, to which it should not be limited, and will be further explained with reference to the drawings. In detail, the drawings show:
System 1 shown is used on a rectangular construction site 10. A plurality of (in this example a total of eight) formworks 2 with partially different dimensions are used. The formworks 2 are each equipped with a transmitter 11 for a locating signal. The positions of the transmitters 11 on the formworks 2 are shown here only roughly schematically. In fact, the transmitters 11 are arranged centred in the middle of the rear side of the respective formwork 2 (cf.
The locating signals sent by the transmitters 11 can be received by the two receivers 4, 5 at the reference points 3. The positions of reference points 3 are known to System 1 and were initialized, for example, during construction using DGNSS or comparable methods. The distance determination unit 6 is connected to both receivers 4, (e.g., via a network connection, such as a mobile data network) and set up to determine a distance between the formworks 2 and the reference points 3 connected to it via a line of sight. The distance is determined on the basis of a locating signal transmitted by the transmitter 11 and received by the receiver 4, 5. For the unambiguous position determination of formworks in two-dimensional space, at least the distances to three reference points are required to perform triangulation without further boundary conditions.
In the example shown in
However, in the example shown, only three formworks 21, 22, 23 have a direct line of sight to both receivers 4, 5.
Therefore, when erecting formworks 2, the position of this formwork 25 will not be able to be determined from two determined distances if formwork 25 is erected after formwork 21. Rather, only the distance 26 to the reference point 3 with the second receiver 5 is known. Accordingly, only the radius 17 of this reference point 3 is shown in
This is where the disclosed invention starts, which is based on the knowledge that the positions of the existing formworks 20, 21, 27 already erected before the fitted formwork 25 allow conclusions to be drawn about the probable position of the newly fitted formwork 25. In order to draw these conclusions, the position database 7 continuously stores the positions of the erected formworks 2 during the installation of the formwork 2, so that at the point in time shown in
The boundary condition of fitting position 28 compatible with the determined distance is illustrated in more detail in
Without the orientation information, fitting positions can also be considered and compared with other orientations of the newly installed formwork, for example a vertical position of the newly erected formwork in the ground layout shown (i.e., parallel to the longer side of construction site 10). However, this would require a significantly smaller distance between the transmitter 11 and the reference point 3 so that it could also be excluded even without the orientation information due to the incompatibility with the determined distance (corresponds to radius 19).
A local zone boundary can cause fitting positions to be discarded. For example, for formwork 32 set up after formwork 25 (cf.
When setting up formwork 33 (cf.
Number | Date | Country | Kind |
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19160866.0 | Mar 2019 | EP | regional |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2020/055782 | 3/5/2020 | WO | 00 |