WO2011048051A1

WO2011048051A1 - Method and device for determining the motion or deformation of large objects

Info

Publication number: WO2011048051A1
Application number: PCT/EP2010/065634
Authority: WO
Inventors: Matthias Fuhrland; Lukas Eng; Torsten Kößer; Christoph Zeh; Danny Stadler
Original assignee: Technische Universität Dresden
Priority date: 2009-10-23
Filing date: 2010-10-18
Publication date: 2011-04-28
Also published as: DE102009045941B3

Abstract

The invention relates to a method and arrangement for determining the motion or deformation of large objects, using measurement locations comprising CCD detector units having CCD rows, wherein the CCD detector units of the measurement locations are displaced into the beam path of a laser by means of stepper motors. Information about the position of the CCD row at the moment of impinging in the laser beam, and information about which CCD cells of the CCD row are illuminated by the laser beam, are transmitted to an analysis unit. The changed location of the object is calculated by means of the analysis unit from the current and previous measurement values and correction values, which are provided by a reference unit.

Description

METHOD AND DEVICE FOR BES IMMUNG IMMIGRATION BZW. THE FORMING OF LARGE OBJECTS

The invention relates to a method of locating large, slow-moving objects using measurement sites comprising CCD detector units with CCD rows, the invention of which is incorporated herein by reference CCD detector units of the measuring points are successively moved in the beam path of a laser. The changed position of the object is calculated by an evaluation unit from the current and earlier measured values as well as correction values that were supplied by a reference unit.

An essential task of industrial metrology is the monitoring of movements or deformations of objects. Typical measurement objects are structures (industrial halls, power plants, dams and towers), traffic facilities, bridge structures, machinery and other industrial facilities (e.g., turbine and conveyor equipment, cycle lines, pipelines, crane runways) and associated natural objects. A continuous event is considered, whereby the processes of deformations of a measuring object and of changes of this object relative to its environment are detected. The objectives of these measurements in industry, facility and risk management are:

the proof of the function and stability of an object and the

Ensuring trouble-free operation,

Timely detection of changes to avoid endangering the object or the environment

Preservation of evidence to clarify causes and damage to the object as well

Forecasts of behavior in the near future and under certain conditions

Load cases.

Since the processes to be monitored are generally smooth and require a minimum of changes in the structure of the structure or structure until a catastrophic change occurs, measurement methods must be used which reliably detect and record these minor changes.

Such measuring methods are usually based on observing deviations from a straight line. The measuring systems used are usually referred to as Aligniersysteme. In the case of the aligning systems, the different measuring variants are based on the fact that the linearity of the arrangement is checked by means of one or more measuring points or the deposition of measuring points to a reference line (escape line) is measured by measurement over a length of up to 300 m. The reference line is so far created in a mechanical or optical way. In the case of a vertical arrangement of the measuring points or measuring points, the method is called plumbing. The measuring range to be recorded is between 5 and 30 cm. Often results from the forces acting on the object and the properties of the environment, in particular the substrate, that a movement of the object in a certain direction is expected. The measuring points and measuring arrangements are then designed so that they can preferably detect movements in the expected direction.

In the mechanical systems, the reference line is realized by a tensioned wire and the changes are read on brackets that are firmly connected to the structure. In the optical systems, the displacement of target characters against the straight target line (reference) of an alignment telescope is measured. Other optical methods use lasers to project measuring marks or to identify measuring point movements due to changed run lengths.

Disadvantages are besides the lack of straightness deviations due to sag and twist. Another problem with wire alignment is that any air movement or contact (e.g., external influences) causes the wire to vibrate, thus degrading the measurement accuracy until the vibration fades. In addition, the use of the free space is impaired because of the limited accessibility between the individual measuring points by the tensioned wire.

The problem of optical systems lies in the fact that due to strong environmental influences (fibrillation, dust and steam) a significantly lower accuracy is achieved and due to the conceptual conditions no permanent observations are possible.

DE 20 2006 003 194 U1 describes a device for monitoring buildings, in which a light beam is directed through a diaphragm on a receiver. As soon as the panel interrupts the light beam due to the movement of the building, an alarm can be triggered. However, this method is only suitable as an alarm system because it provides no statements about quantitative changes over time.

In DE 20 2006 001 480 U 1, a system is presented in which at certain measuring points of a building to be monitored Lichtumlenkpunkte are attached, which are continuously irradiated with light. The changes are recorded and documented via an evaluation system of the light propagation time. The triggering of alarms when exceeding permissible limits is also provided. US 2008/0030710 A1 describes a method for monitoring a bridge carrier by means of a laser-assisted rangefinder. A reflective measuring point throws the laser light back to the meter and thus allows the remeasured distance determination. Changes in this distance are recorded and evaluated in a wireless or wired station connected to the rangefinder.

The two aforementioned solutions have in common that each measuring point to be monitored is also assigned a laser system.

Due to the ever-increasing complexity and size of the structures to be monitored as well as the increased safety standards in industry and the environment, the demands for highly accurate, permanently operating, personnel-, ze- and cost-saving monitoring systems are becoming ever greater. The goal is to monitor risky objects for their deformations, shifts or changes in real time.

The object is to present a method and a device that realize changes to structures and other objects in need of monitoring by the continuous monitoring of one or more measurement points by means of a laser-based system.

This problem is solved according to the invention by the method disclosed in claim 1. An arrangement which is suitable for solving the problem is presented in claim 6. Advantageous embodiments are shown in the dependent claims.

The inventive method solves the problem by at least one CCD line, which is always in a defined position to the object to be observed, periodically or aperiodically in a reference line serving as laser beam is introduced and both the position of the CCD line at the moment of entry into the laser beam as well as information which CCD cells of the CCD line are illuminated by the laser are transmitted to an evaluation unit. The evaluation unit uses this data as well as reference data for the course of the laser beam to calculate the position of the building. The obtained and calculated information can be stored in the device or forwarded.

A laser unit generates a laser beam or a laser plane, which represents the reference line or plane. The measuring units attached to the measuring or monitoring object are with ochempfindlichen CCD line sensors and directional and color filters fitted. Via a continuous rotation (stepping motor) of the CCD line sensors they cut the laser beam within a short time, whereby only a few CCD cells of the CCD line sensors are illuminated. After each impingement of the laser beam, the CCD cells are read out by the evaluation unit, in order subsequently to calculate the position of the laser beam relative to the respective measuring point to submillimeter accuracy using a calculation algorithm. The calculated position is provided with a time stamp and then either stored in a data memory ("post-processing") or forwarded to the real-time evaluation software for analysis.

The previously divergence of the laser beam affecting the accuracy and functionality of the position detection and the resulting increase in the beam diameter is achieved by the use of a special laser diode with a max. Beam expansion of 0.5 mrad and the use of a specially designed focusing device reduced and controlled. In addition, instabilities of the beam direction occurring by the reference detector are detected. From this, the evaluation unit determines correction parameters and uses these to correct the calculation results and / or the settings of the laser unit.

The system enables automated permanent observations at several measurement points due to the periodic repetition of the described method. By a slight angular offset of the CCD detector units at the different measuring points, it is possible to carry out measurements at different distances almost simultaneously. With this measurement principle, neither the laser power is affected nor is it necessary to deflect or deflect the beam and thus the accuracy, functionality and reliability can be guaranteed even for long ranges. The system can determine movements of the object to be observed in a plane orthogonal to the beam path of the laser.

In a preferred embodiment, the system has a control unit that moves the CCD detector units into defined rest positions. The control unit then selects, for. B. according to a predetermined program, a measuring point and controls the stepping motor so that the CCD line of the CCD detector unit enters the beam path of the laser. Subsequently, the measurement is analogous to the operation with continuously operating stepper motors. After the measurement, the control unit causes the movement of the CCD detector unit back to the rest position and thus moves the CCD line out of the beam path of the laser beam. This procedure is repeated with the other measuring points. The method may be aperiodic, due to a program control, manually be triggered or repeated event-controlled. The control unit may be integrated into the evaluation unit or designed as a separate unit.

A preferred embodiment of the method provides for arranging on the side of the moving object opposite to the laser a reflector which reflects the laser beam so that it strikes the reference unit, which in this case is arranged on the same side of the object as the laser. The laser beam is guided so that it passes on the way to the reflector (as original beam) the measuring points on one side at a distance in which the measuring points can detect him with the CCD line. On the way from the reflector to the CCD reference detector (reflected beam), it passes the measuring points again, even at a distance that allows a measurement. In this preferred arrangement, the measuring points have two CCD lines, one on the side facing the original beam (the front side) and one on the side facing away from this (the rear side). The current measuring point now rotates the CCD line on the front of the CCD detector unit first in the one beam path, for example, that of the laser to the reflector, and measures. Subsequently, the CCD line of the backside is moved in the other beam path, e.g. from the reflector to the CCD reference unit, and now measured again with the second CCD line. Based on the two angular positions of the CCD detector unit, the exposed CCD cells, the information of the reference unit and the known positions of laser, reflector and CCD reference unit not only the movement in a plane orthogonal to the beam path of the laser but also the movement along calculate the connecting line of laser and reflector.

The automated laser tagging system provides customers with a faster, more reliable, more accurate, and in the long term cost-effective way to monitor structural deformations, to inspect roof structures, and to monitor industrial machinery and equipment. The almost simultaneous, automated permanent observations at several measuring points and the real-time analysis of the recorded data make a significant gain in security possible by setting up an early warning system. Furthermore, a much larger measuring range is covered than is possible with existing technologies. The installation and calibration of the system as well as the execution of the monitoring measurement can be done by only one person. The high flexibility of the system allows the adaptation to special customer or object requirements without much effort.

The susceptibility of known solutions and methods (mechanical and optical) to external influences (air movement, contact, fibrillation, dust, vapor and Refractio n), you will be able to minimize the amount of time needed for the system's regular calibration, laser beam stabilizing measures, and automatic corrections from reference detectors and data loggers. Twisting and slack are not important when using a laser as a reference, as well as a brief interruption of the laser beam does not affect the measurement. Only the record recorded at the time of interruption is marked and not taken into account in the evaluation

An apparatus for carrying out automatic laser signaling has at least one laser, a reference detector, an evaluation unit and at least one measuring point. The measuring point has a CCD detector unit which is rotatably arranged and is rotated by a stepping motor. The measuring point or measuring points are attached to the object whose movement is to be observed. The laser is placed outside the anticipated moving zone of the object and emits a laser beam that is approximately parallel to the surface of the object (s) to be observed and impinges on the CCD reference director, which is also located outside the anticipated motion zone of the object , The laser beam passes on the axes of the stepper motors at a distance from this, which allows the CCD lines of the CCD detector units can enter the beam path. The CCD detector units are preferably platinum-shaped, ie they have a flat, card or web-like shape. Each CCD detector unit has a CCD line on a front side facing the laser. Each CCD detector unit is in turn mounted with one of its edges on the axis of a stepping motor so that the CCD line of the detector unit is aligned orthogonal to the axis of the stepping motor, which thus in turn approximately parallel to the surface of the object to be monitored and the connecting line of laser and Reference unit runs. When the stepper motor is operating, the detector unit describes a circular motion. Depending on the position of the CCD detector unit, it interrupts the laser beam or not. In the course of the further rotation of the CCD detector unit into the course of the laser beam, a point is reached at which the laser beam strikes the CCD line of the CCD detector unit. The information about the angle of the CCD detector unit, which results from the step sequences of the stepping motor, as well as about which CCD cells of the CCD line reaches the laser beam are transmitted to the evaluation unit. The evaluation unit calculates two-dimensional coordinates of the position of the measuring point from the transmitted information. Due to the known position of the measuring point and the time series resulting from repeated measurements, information about the movement of the object to be observed orthogonal to the laser beam can be obtained. This results in the movement of the object under consideration that is, the reference unit supplied values. Any deviations of the laser alignment or other environmental influences can be considered in the evaluation. In the evaluation unit, the data can also be collected for later evaluation.

If several measuring points are operated continuously, the rotations of the CCD detector units are coordinated in such a way that each measuring point is regularly illuminated and the CCD detector units are not mutually shadowed. The measurements are made periodically.

In a preferred embodiment, the measuring points are not operated continuously and thus the measurements are made aperiodically. The control unit controls the stepper motors of the inactive measuring points such that the CCD detector units are located in a defined rest position outside the beam path of the laser beam. Only the stepping motor of the active measuring point is controlled by the control unit and moves the CCD detector unit into the beam path of the laser beam. After the measurement, the control unit controls the CCD detector units back to the rest position and repeats the process with the next to be queried measuring point. This procedure allows a much larger number of measuring points to be used than if the stepper motors are in constant motion and there is a risk, at several measuring points, that measuring points closer to the laser will shade remote measuring points with their CCD detector units.

In a further preferred embodiment, the laser and the CCD reference detector are arranged on a common side of the object to be observed, and the laser beam is directed into the CCD reference unit via a reflector located on the other side of the object. The beam path of the laser leads past the measuring point so that the CCD detector unit can measure in the path of the laser beam from the laser to the reflector and from the reflector to the reference unit. For this purpose, the CCD detector unit on the front and the back has a CCD line. From the measured data, the evaluation unit can determine not only the movement orthogonal to the laser beam, as in the arrangement without a reflector, but also along the line connecting the laser and reflector. The individual measuring points let their CCD detector units rotate continuously or are controlled by a control unit that controls each measuring point according to a predetermined program and the CCD detector unit from the rest position in the beam path from the laser to the reflector and then in the beam path from the reflector to the CCD -Refference unit rotates and the CCD detector unit finally back into the Resting position moves. It is irrelevant whether measured first in the beam path from the laser to the reflector or first in the beam path from the reflector to the CCD reference unit. It is only essential that the measurements in both beam paths are made in a timely manner, preferably in immediate succession. Subsequently, the data is transmitted from the measuring point to the evaluation unit, which can now determine both the movement in a plane orthogonal to the line connecting the laser and the reflector, including the previously measured values, as well as the movement along this connecting line. The evaluation also includes data from the CCD reference detector and the known positions of the laser, reflector and reference detector. This process can also be carried out with the remaining measuring points. The control unit can be designed as a stand-alone device or as part of the evaluation unit.

The invention will be explained below with reference to FIGS 1-4.

Show it:

Fig. 1: measuring arrangement by way of example with four measuring points. The expected direction of movement of the object (1) runs in the y-z plane. The stepper motors (2) of the four measuring points are constantly in operation here. Due to the different angular positions of the CCD detector units, there is no danger of shading further from the laser remote measuring points by closer to the laser.

Fig. 2: Basic structure of a measuring point with the stepper motor of the measuring point (2), the CCD detector unit (8) and the CDD line (1 1). The CCD detector unit is mounted on the axis (10) of the stepping motor (2). The attachment of the measuring point (2) takes place on the surface of the object (1). The expected direction of movement of the object (1) is approximately orthogonal to the axis (10) of the stepping motor of the measuring point (2) and the laser beam (6) in the y-z plane. The laser beam (6) is generated by the laser (5) and strikes the CCD line (1 1) with the CCD cells (12). If the CCD detector unit 8 is not in the beam path of the laser beam (6), the beam hits the reference unit (3).

Fig. 3: movement of the CCD detector unit (8). The CCD detector unit moves from the position A in steps (B-F) on, wherein in the position B of the laser beam on the CCD line (1 1) meets and here the measurement is made. The actual step size is much smaller than shown in this schematic diagram.

Fig. 4: Inventive arrangement using a reflector (9). The CCD Detector unit (8) receives in the position G, the laser beam (6) on the way from the laser to the reflector in its CCD line (1 1). In position H, the reflected laser beam is detected on the way from the reflector (9) to the CCD reference unit (3) by a second CCD line (1 1) on the back of the CCD detector unit. In this embodiment, from the positions of the CCD detector unit (8) upon impact of the laser beam (6) on the CCD lines (1 1) in addition to the movement in the yz plane information for movement in the x direction can be detected.

LIST OF REFERENCE NUMBERS

1 object to be observed

2 stepper motor of the measuring point

3 reference detector

4 evaluation unit

5 lasers

6 laser beam

7 Connection to the evaluation unit for transmitting information

8 CCD detector unit

9 reflector

10 axis of the stepper motor

1 1 CCD line

12 CCD cells

Claims

claims

1 . Method for determining the position of one or more slowly moving objects (1), wherein for each object to be observed (1) at least one CCD line (1 1) exists, which is constantly in a defined position to the respective object (1) and in a reference laser beam (6) and information about the position of the CCD line (1 1) at the moment of entering the laser beam (6) and information about which CCD cells of the CCD line (1 1) are exposed by the laser beam (6), are transmitted to an evaluation unit (4).

2. The method according to claim 1, characterized in that information about the position of the laser beam (6) from a reference unit (3) to the evaluation unit (4) are transmitted.

3. The method according to claims 1 and 2, characterized in that the evaluation unit (4) provides the transmitted information with time stamps and stores.

4. The method according to claim 1, characterized in that the method is repeated periodically or aperiodically and the CCD line (1 1) between the repetitions of the beam path of the laser beam (6) is removed.

5. The method according to claim 1, characterized in that the evaluation unit (4) acquires information of a plurality of measurements, the time stamps and the information of the reference unit (3), the movement of the object to be observed (1).

6. Arrangement for determining the movement of one or more slowly moving objects (1), at least consisting of a laser (5), a reference detector (3), at least one measuring point (2) which is mounted on at least one slowly moving object (1) is arranged and an evaluation unit (4), wherein

The laser (5) provides a laser beam (6) which runs along the slowly moving object (1) or the slowly moving objects and impinges on a reference detector (3) beyond this object (1) or these objects,

• the reference detector (3) provides information about the impact point of the Transmitted laser beam (6) in the reference detector (3) to the evaluation unit (4),

• Each object (1) whose movement is to be determined, has at least one measuring point (2), the at least one stepper motor with an axis

(10), wherein the axis (10) of the stepping motor is aligned approximately parallel to the direction of the laser beam,

• A CCD detector unit (8) at one of its edges on the axis (1 0) is fixed, wherein the CCD detector unit at least one CCD line

(1 1) oriented orthogonal to the axis of the stepping motor,

The stepping motor can rotate the CCD detector unit 8 into the beam path of the laser 6 and the laser 6 strikes the CCD line 11;

• the evaluation unit (4) obtains information from the measuring point (2) or the measuring points over which the position of the CC D detector unit (8) the CCD line (1 1) of the laser beam is located (6) was hit and which cells of the CCD line (1 1) were hit by the laser beam (6)

7. Anord tion according to claim 6, characterized in that the CCD reference unit (3) is located together with the laser (5) on one side of the object and the arrangement further comprises a reflector (9) on the opposite side of the object (1 ) which reflects the laser beam (6) again along the slowly moving object (1) and the CCD detector unit (8) has two CCD lines and measures both in the unreflected and in the reflected part of the beam (6).

8. Arrangement according to claim 6 or 7, characterized in that the evaluation unit (4) stores the transmitted information.

9. Arrangement according to claim 6 or 7, characterized in that the evaluation unit (4) further processes the transmitted information and from the information of the measuring point (2) or the measuring points and the reference unit (3), the movement of the object (1) or of the objects.

10. Arrangement according to claim 6 or 7, characterized in that the evaluation unit (4) compares the transmitted or determined information with reference values and upon reaching or exceeding reference values, a predefined action is triggered.

1 1. Arrangement according to claim 6 or 7, characterized in that the transmission of the information to the evaluation unit (4) takes place without wires or by wire.

12. Arrangement according to claim 6 or 7, characterized in that the stepper motors of the measuring points (2) are continuously in operation and the CCD detector units (8) are permanently in rotating motion, the CCD detector units (8) with an angular offset from each other on the respective axes (10) of the stepper motors are arranged so that in the beam path of the laser (6) located CCD detector units (8) shade any other, also located in the beam path CCD detector units (8).

13. Arrangement according to claim 6 or 7, characterized in that the CCD detector units (8) of the measuring points (2) are located in a defined rest position outside of the radiation source of the laser beam (6) Control unit controls the stepper motor of a measuring point (2) so that the CCD line (1 1) of the CCD detector unit (8) in the beam path of the laser (6) is moved.

14. Arrangement according to claim 6 or 7, characterized in that the CCD detector units (8) of a part of the measuring points (2) are in a defined rest position outside the beam path of the laser beam (6) and a control unit, the stepper motors of several measuring points (2 ) so that the CCD lines (1 1) of the CCD detector units (8) are moved into the beam path of the laser (6) so that they do not shadow each other.

15. Arrangement according to claim 13, characterized in that the control unit is integrated in the evaluation unit (4).

16. Arrangement according to claim 13, characterized in that the control unit is spatially separated from the evaluation unit (4).