Measuring setup and method for optical or quasi-optical position determination

Abstract

Measuring arrangement (1) for optical or quasi-optical determination of the position or orientation of at least one object, comprising at least one base station (2) and at least one active target (3) spatially fixed to the object within the detection range of the base station (2), characterized in that the base station (2) is designed such that it generates a wobbling beam plane (4), during the wobbling motion of which the normal of the beam plane rotates with a rotation angle known at all times about a rotation axis (18) inclined to the normal by a predefined, largely constant angle of inclination, wherein the active target (3) is hit by the beam plane at least twice per rotation of the normal.

Description

[0001] The present invention relates to what is claimed in the generic term and accordingly deals with a measuring arrangement and method for optical or quasi-optical position determination, consisting of at least one object whose position or orientation is to be determined, as well as at least one active target spatially fixed to this object and at least one base station in whose detection range the active target falls.

[0002] Such measurement arrangements are already known from the state of the art and have been used in a wide variety of fields, such as virtual reality, industrial surveying, construction surveying, and construction machinery control. For example, US 2015 / 0 037 045 A1 discloses a base station that emits a beam plane and is used in conjunction with a suitable receiver, where the beam plane can be tilted.

[0003] Historically, automatically tracking distance measuring devices (laser trackers for industrial surveying or robotic total stations for land surveying) were developed for such applications. These already expensive systems, although still very popular, still have the disadvantage that only one base station can track a single target, usually passively, e.g., a retroreflector, but sometimes actively.

[0004] This approach is still very complex and expensive, for example, when controlling construction machinery, preferably entire, possibly even autonomous road paving columns (road pavers and several rollers), because at least one base station must be maintained for each object to be tracked or measured or for each measuring point on it.

[0005] In the field of construction machinery control, systems were quickly added that enabled highly precise height control using rotating lasers and matching line-shaped machine receivers. However, such systems are tied to a single laser plane, which can be disadvantageous on uneven terrain. In this context, EP 2 998 699 A1 proposes a method for controlling the paving height and layer thickness control of road construction machines. The disclosure content of this document is incorporated by reference. This method, known from the prior art, is described in Fig. 13. In general, the chain-like arrangement of several angle-measuring, mutually leveling rotating laser transceivers 66a .. 66g (TRX) is intended to replace a guide wire or string line, as is typically used to control the paving height of road pavers, with a virtual version (virtual guide wire, virtual string line) 64, defined by segmented laser planes 72 along the road 67, in order to avoid the high effort involved in laying such conventional guide wires. The advantage is that the virtual guide wire, by smoothing or interpolating the segments, allows for significantly greater distances between the support points (here, base stations, rotating laser transceivers), which significantly reduces the calibration effort for the section to be paved.Against this background, it should be pointed out that the costs for a surveyor to measure a few kilometers of conventional guide wire can already exceed the system price of such an improved system, meaning that this system pays for itself in significantly less than one year.

[0006] The chain-like arrangement significantly reduces, but does not completely eliminate, the usual limitations in the height measurement range. This is due to the fact that... Fig. Figure 12 shows a typical configuration of a hot asphalt paving 68 with two machines.

[0007] To receive the laser planes, for example, very long and therefore expensive laser receiver lines 71, such as those shown in US 2018 / 0 259 332 A1 by the applicant, must be mounted on the paving screed 70 of a road paver. Due to their weight, these lines pose problems with measurement accuracy when exposed to vibrations. The same applies to mounting them on the suspension of the rolling element of a road roller.

[0008] A compromise must therefore be made between flexibility, cost, and operational availability. A further disadvantage is the fact that each transceiver (66) can only emit one laser plane, which requires a transceiver for each support point of the virtual stringline, which simultaneously contains both a base station and an active target. Such devices must be specifically developed for this purpose and are hardly suitable for universal applications.

[0009] It would therefore be desirable to have a measuring arrangement and a method which have the above-mentioned advantages of EP 2 998 699 A1, but which, by emitting more than one virtual laser plane, allows a base station or a stationary, active target to be provided for only every second support point of the virtual string line in order to further reduce the system costs considerably and to finally solve problems with the height measurement range.

[0010] This is solved by the measuring arrangement and method claimed in the generic term.

[0011] It should also be expressly pointed out that partial aspects of the invention disclosed here, such as the optical data transmission via the laser beam, for example with rotation angle data or the transmission of auxiliary information, can also be advantageously applied to the transceivers from EP 2 998 699 A1, as well as to any rotary laser, which is thus enabled to determine horizontal angles without implementing external synchronization, e.g. by radio or separate IR data transmission.

[0012] Another alternative approach to state-of-the-art tachymeters, laser trackers or rotating lasers is the use of real-time kinematic GNSS receivers, which allows for any number of relatively inexpensive active targets, but brings problems with measurement accuracy and with multi-path reception and shadowing, e.g. in urban canyons, as well as availability problems with correction services and satellite systems.

[0013] To solve the aforementioned diverse cost, accuracy, and availability problems, several approaches using rotating beam fans have been developed in the past to overcome such limitations. The base stations of the state-of-the-art measurement arrangements are in Fig. 1a to Fig. 1d shown.

[0014] At Fig. 1a is the base station disclosed in US 7 394 527 B2 of the applicant and in US 5 767 960 A, with three fan beams emitted from a rotating base distance, which allow an active target synchronised by radio or cable connection to calculate the distance, the height and a horizontal angle of the active target in the polar cylindrical coordinate system of the base station from the temporal sequence of the three hits of the fan beams on the active target.

[0015] Fig. Figure 1b shows the base station particularly preferred in EP 1 434 029 A2 with three beam planes emitted from the center of rotation, enabling the active target to calculate a horizontal angle and a vertical angle in the polar coordinate system of the base station.

[0016] Fig. 1c Shows an alternative arrangement from the prior art according to US 4 441 809 A. The properties correspond largely to those of Fig. 1a, with the difference that at least two active targets are required to determine more than one elevation angle.

[0017] Fig. Figure 1d again shows a base station from US 5 110 202 A with two rotating beam fans, with which the active target can calculate a horizontal angle and a vertical angle in the polar coordinate system of the base station.

[0018] All these in Fig. 1, the approaches described as state-of-the-art have in common that they are based on rotating laser optics that emit at least two to three beam fans to determine up to two directional angles relative to an active target to be tracked. For this purpose, time measurements of the impact times of the individual beam fans are used.

[0019] Another common advantage is that all these approaches Fig. 1 allow, at least in principle, to span virtually any number of virtual laser planes located within the base station through its projected measuring space and with the help of the vertical and horizontal angles measured therein, which can be individually calculated on the active target.

[0020] Another common feature and their most serious disadvantage is that such approaches are based on the fact that the two or more beam fans must be guided through different (cylindrical) optics, which in turn have different aberrations that do not cancel each other out, which means that the high-precision determination of vertical angles is not possible without complex, costly and time-consuming factory calibration in several dimensions due to the very critical necessary flatness or synchronism of the beam fans.

[0021] Another characteristic is the loose, or sometimes lacking, synchronization between the active target and the base station for measuring horizontal angles, which places considerable demands on the synchronization of the rotating laser heads. Typically, 0.001% to 0.0001% synchronization values ​​are required to achieve angular accuracies of a few arc seconds for vertical and horizontal angles. These requirements necessitate the use of expensive and fragile low-friction bearings and large flywheel masses, which quickly renders practicality questionable and, due to the upscaling of the entire base station, causes the system price to skyrocket.

[0022] Since at least the approaches from Fig. 1b and Fig. 1d continue to enjoy great popularity among users in the field of construction machinery control and industrial surveying, it is obvious to create an alternative based on a new measuring principle which does not have the above-mentioned disadvantages and has properties which promise wide application in other areas and also allows an inventive alternative or improvement of the method according to EP 2 998 699 A1.

[0023] In particular, it would be desirable if a single tumbling beam plane (area-shaped profiled beam, beam area or beam fan) emitted by the base station from the optical and quasi-optical wavelength spectrum is sufficient to determine two directional angles (a vertical angle λ and a horizontal angle φ) when sweeping over the active target.

[0024] This makes it easy to ensure that the beam path passes through the same optical components of the base station during at least two beam passes of a rotation or scanning movement and that a large part of the linearity errors with regard to the measurement of vertical angles cancel each other out. Thus, a fast one-dimensional calibration of vertical angle offsets is sufficient to measure vertical angles with accuracies down to the sub-arc second range.

[0025] It would also be desirable if the angular synchronization between the base station and the active target were not carried out as before - delayed and loose - via separate, interference-prone radio or infrared data transmission, but directly, by modulating the radiation of the beam plane with an angle-coded data signal and optionally further auxiliary information from the base station. This measure can reduce the requirements for the synchronization of the rotation by more than two orders of magnitude, and eliminate the need for costly bearings and flywheels.

[0026] It would also be desirable if the wobbling beam plane covered a large measurement space, making it possible to calculate any virtual laser planes passing through the emission center of the wobbling motion on the side of the active target without additional measures.

[0027] The object of the present invention is to provide a measuring arrangement and a method for optical or quasi-optical position determination that fulfills at least some of the aforementioned requirements in whole or in part.

[0028] The solution to this problem is claimed in an independent form. Preferred embodiments are found in the dependent claims.

[0029] Thus, among other things, a measuring arrangement for optical or quasi-optical position determination is proposed, which consists of at least one object whose position or orientation is to be determined, at least one active target spatially fixed to this object and at least one base station in whose detection range the active target falls, wherein the base station generates a wobbling beam plane.

[0030] In the context of this document, the term "beam plane" always refers to an entire class of planar beam profiles according to the invention, such as, for example, a largely undistorted flat surface, except for imaging and alignment errors, as well as conical surfaces with a round, elliptical, or slightly wavy base profile, as well as beam fans or coplanar multiple beam fans caused by shadowing, as well as beam surfaces of these aforementioned types distorted by imaging and alignment errors. For better understanding, however, an ideal, flat plane is assumed, especially for the given formulas.

[0031] The wobbling motion is preferably defined by the fact that the normal or axis of symmetry of the beam plane rotates around a rotation axis that is not parallel to this normal and is oriented at a known and / or largely constant angle of inclination α relative to it, and that the active target is struck by the beam plane at least twice per rotation of the normal at rotation angles ψ1 and ψ2. The rotation axis is usually largely perpendicular in space, but its orientation is not necessarily limited.

[0032] This measuring arrangement can further be characterized in that the at least two angular positions of the rotation of the normal of the beam plane around the axis of rotation at the times of the at least two hits per revolution or pivot are used to calculate at least one directional angle with respect to the polar coordinate system of the base station.

[0033] It can further be provided that the active target is designed to calculate at least one vertical direction angle λ with respect to the polar coordinate system of the base station.

[0034] It should also be possible for the active target to be designed to calculate at least one horizontal direction angle φ with respect to the polar coordinate system of the base station.

[0035] To achieve the wobbling beam plane motion, the base station can be designed to include a rotating beam deflection component. This could be, for example, a rotating transmissive refractive angle prism, a rotating mirror suspended at an angle to the normal / axis of symmetry, axicon or cone optics, or any other rotatable arrangement of multiple optical components capable of deflecting a collimated beam around its direction of propagation by an angle α.

[0036] It may also be provided that the base station contains a beam plane expansion component.

[0037] For example, this can take on the function of a conical mirror to generate the beam plane. This can be designed with any cone angle, but preferably 90°. Plano-concave axicons with internal reflection and lateral coupling via the lateral surface, or cylindrical optics, as well as any other combination of suitable optical components, are also conceivable.

[0038] Furthermore, it can be provided that the base station contains an optoelectronic beam transmitting element, the radiation of which is or is collimated to a specific aperture angle, e.g. to propagate as parallel as possible (i.e. to infinity).

[0039] Possible applications include laser diodes, solid-state lasers, LEDs, and arrays of these with individually controllable elements that share the same collimator optics, as well as Gunn diodes or other RF emitters for the quasi-optical wavelength range.

[0040] It is also conceivable, as is usually possible in the optical field, to replace the optoelectronic beam transmitting element with an optoelectronic beam receiving element (photodiode, APD, SiPM, detector array, CCD, etc.) while reversing the radiation direction. This means that the beam plane is not the directional characteristic of a transmitted (light beam), but rather the directional characteristic of a light beam receiver. If the role of the receiving element in the active target is then swapped to a transmitting element, this results in another novel measuring arrangement according to the invention for position determination on the base station side.

[0041] It can also be provided that both an optoelectronic beam transmitting element and an optoelectronic beam receiving element are brought into the focus of the collimation optics, e.g. using a polarizing beam splitter with an A / 4 plate. This enables the base station to perform directional measurements on highly reflective passive targets, such as the corner cube reflectors (cat's eyes) used in total stations, as well as pulse transit time measurements to determine entire 3D coordinates. This allows base stations to, for example, calibrate themselves to one another or perform 3D measurements similar to robotic total stations. The advantage here, however, lies in the significantly simpler optomechanics, which only requires a single precise axis of rotation compared to the two axes of rotation in a total station.

[0042] It is further preferred that the collimated beam is deflected by a rotating beam deflection component and expanded to the tumbling beam plane by the beam plane expansion component.

[0043] The measuring arrangement can be extended by providing a means for modulating the optoelectronic beam transmitting element with an angle-coded data signal.

[0044] The data signal can, for example, contain the current angular position of the rotation axis of the beam deflection component, which is obtained, for example, by an angle encoder.

[0045] It is also desirable that provisions be made for the transmission of additional auxiliary data across the beam plane, at least intermittently, in addition to the angle data, such as the position of a tilt sensor or tilt compensator for subsequent compensation of the tilting of the base station when the target is active, as well as battery level, temperature, or the like.

[0046] In order to ultimately determine direction angles with high accuracy, the active target can be equipped to determine the angular position of the rotation of the normal of the beam plane around the axis of rotation from the radiation of the beam plane modulated with the angle-coded data signal and auxiliary data at the time of impact and a temporal center-of-gravity calculation of the beam reception for interpolation between the transmitted discrete angular steps.

[0047] Alternatively, beam reception can also be achieved by optimizing a model for the course of a typical beam reception, e.g. using an LMS method or an appropriately trained neural network (AI).

[0048] Protection is also claimed for a process according to the independent process claim.

[0049] This enables a method for determining the height and position of a vehicle with a measuring arrangement for optical or quasi-optical position determination, which consists of at least one active target permanently related to the vehicle and at least one base station, in whose detection range the active target falls, wherein at least one further, stationary, active target is provided and the connecting line between the base station and the stationary active target spans a segment of a virtual guide wire, as well as a virtual laser plane with a predefined transverse inclination, on which the vehicle is guided at its working height, comparable to a conventional guide wire, with the aid of the directional angles of the base station obtained by the active targets.

[0050] The method for determining the altitude and position of a vehicle can preferably be extended by several alternating segments consisting of base stations and stationary active targets forming a chain of segments of a virtual guide wire.

[0051] Each base station is assigned two virtual laser planes, which are mathematically determined from the direction angles of the station by the adjacent stationary active targets.

[0052] In the method according to the invention, additional information such as intersection points of the directional angles with the planned course of the vehicle's journey (e.g. parallel with a constant distance to the virtual string line) can preferably be blended or odometers can be calculated in order to determine necessary control parameters for interpolation and smoothing of the reference variable at the transition points of the segments.

[0053] The invention is described below by way of example only with reference to the drawing, which is illustrated by: Fig. 1 Four different exemplary measurement setups from the state of the art (already explained). Fig. 2 Overview of a preferred measurement setup Fig. 3 Preferred measurement arrangement with active target at two different heights. Fig. 4 Measurement arrangement with two active targets with known base distance b, to eliminate ambiguity and determine 3D coordinates with a base station. Fig. 5 Measurement setup with an active target and a GNSS antenna to eliminate ambiguity and improve the 3D coordinates of the GNSS antenna. Fig. 6 Measurement arrangement with two base stations to eliminate the ambiguity with base distance b Determination of 3D coordinates of an active target. Fig. 7 Six different arrangements of optical components in the base station. Fig. 8 Cross-sectional view of the optomechanics of a particularly preferred design of the base station. Fig. 9 Block diagram of the control circuit of the particularly preferred embodiment of the base station. Fig. 10 Block diagram of a particularly preferred embodiment of the active target. Fig. 11 examples and explanations of the possible design of the angle-coded data signals in the base station and after reception in the active target. Fig. 12 Attachment of laser sensors to construction machinery in a method for guiding construction machinery in road construction (state of the art, already explained). Fig. 13 Top view of a road using the same method from the state of the art (already explained). Fig. 14 Mounting of the active targets in the proposed method for determining the altitude and attitude of a vehicle. Fig. 15 Virtual laser planes and interpolation at the transition between the support points of the virtual string line according to the invention. Fig. 16 Top view of a road layout using the same method with virtual stringline and road paver.

[0054] The Fig. The preferred measuring arrangement 1 shown in Figure 2 consists of an object to be measured (not shown), to which the active target 3 is attached, held, or otherwise brought into a fixed spatial relationship. The active target consists of a receiving collimator 40, which bundles the incoming light rays from the base station 2, which is attached to a tripod with a tripod 36, into a light guide 41 as soon as the wobbling beam plane 4 of the base station passes over it. The optical signals are transmitted through the light guide to the receiver 42 for angle determination. The wobbling movement is defined by the fact that the normal of the beam plane rotates about an axis of rotation 18 that is not parallel to this normal and has a predefined, largely constant angle of inclination α to it, with a rotation angle ψ that is known at all times, and that the active target is hit by the beam plane at least twice per rotation of the normal.A distinction must be made between an event in which the beam plane sweeps over the active target from bottom to top (rotation angle ψ1) and the second event in which the beam plane sweeps over the active target from top back to bottom (rotation angle ψ2). The axis of rotation is preferably vertical.

[0055] The horizontal direction angle (not shown) is then calculated as: φ=ψ1+ψ22

[0056] The vertical direction angle is calculated as: λ=atan(tan(α)⋅cos(ψ2−ψ12))

[0057] It should be noted that if it is not known whether the hit events pass the active target from bottom to top or in the opposite direction, an ambiguity arises for two temporally consecutive angles ψ1 and ψ2, where it is not possible to distinguish whether the direction of the active target is 180° opposite to the calculated direction. This ambiguity can be resolved by restricting the measurements to a half-space from the outset, or by adding temporal information from a second active target (see Fig. 4) or additional position information from a GNSS antenna (see Fig. 5) or resolves the ambiguity by adding another base station and performing 3D triangulation.

[0058] In Fig. Figure 3 now symbolically shows how the received rotation angles change when the height of the active target is changed. Only the distance between the two rotation angles ψ1 and ψ2 changes, not their mean value, which is already expressed by formulas (i) and (ii). The same applies to the temporal relationships, provided the rotation speed of the normal remains constant.

[0059] In Fig. Figure 4 shows how the ambiguity can be resolved by taking into account the sequence of rotation angles using two active targets 3a and 3b arranged one above the other at a known vertical base distance b. Furthermore, using the base distance b, it is possible to calculate the height coordinate z and the distance to the base station r. This provides the 3D position of the active target in the polar coordinate system of the base station. If, for example, the active targets are attached to a measuring rod at a constant distance b*, the tilt can be compensated at any time using the measured values ​​of an inclinometer in the measuring rod and converted to b.

[0060] In Fig. Figure 5 shows how the ambiguity can be resolved by connecting the active targets 3 to a GNSS antenna and, at the same time, by intersecting the two directional angles with the GNSS position, the accuracy of the latter can be improved, especially in the altitude measurement.

[0061] Fig. Figure 6 shows another arrangement in which the ambiguity is automatically resolved. Here, two base stations 2a and 2b are set up at a known base distance b and aligned with each other with respect to their horizontal axes.

[0062] An active target 3, located in the measurement space of both base stations, can then be determined in its 3D position by 3D triangulation.

[0063] Particularly preferred is the variant already mentioned, in which the base stations can measure both the horizontal angle and vertical angle of passive targets 34a and 34b, mounted in alignment with the rotational axis of the other station, as well as the transverse distances via pulse transit time, insofar as the base stations are equipped with corresponding extensions as already described.

[0064] The advantage is that the stations can calibrate themselves automatically during setup, and the information obtained about the neighboring stations can be transmitted as auxiliary information via the modulated beam plane to the active target, without the target having to initiate the calibration process or query it via the radio interface. The setup process is as simple as with a total station.

[0065] In Fig. Figure 7a shows the arrangement of the optical components of a particularly preferred variant of the base station. The optoelectronic beam transmitting element 12, e.g., a laser diode, emits a divergent beam bundle, which is converted into a largely parallel, collimated beam by a collimator component 10, e.g., a biconvex lens of the best shape. This beam then strikes the rotating beam deflection component 7, in this case, a rotating angle prism, where it is deflected by the deflection angle α. The axis of rotation 8 is preferably parallel to the propagation of the collimated beam 11. The axis of rotation, and thus the angle prism, is driven by a motor 18 that generates the rotational movement.

[0066] The now deflected, collimated beam then falls onto the beam plane expansion component 5, implemented here as a 90° conical mirror, which converts the deflected, collimated beam into the wobbling beam plane 4. It can be seen here that, due to the lateral offset on the conical mirror resulting from the deflection, the thickness of the beam plane varies, and there is also a slight vertical offset and slight differences in optical power within the beam plane. However, this slight imaging error when generating the beam plane can be precisely calculated and compensated for mathematically. In addition, the tip of the conical mirror can almost touch the surface of the angle prism without any beam shadowing of the beam plane if the inclination angle of the beam plane exactly corresponds to the prism angle, which is the case with a refractive index of 2.0 for the material of the angle prism.

[0067] Fig. 7b shows the same arrangement as Fig. 7a, except that here the position of the beam paths is shown for a position of the angle prism rotated by 180°.

[0068] Fig. Figure 7c shows how the above-described misalignment problems can be largely optically compensated by adding a tilted parallel plate to the rotating beam deflection component 7. The beam deflection component 7 thus consists of an angle prism and a tilted parallel plate.

[0069] Fig. Figure 7d shows a further refinement of Fig. 7a, where the parallel collimated beam is formed as a collimated ring beam by adding two axicons in the collimator. This has advantages with regard to the divergence of the beam plane on the vertical, allowing for longer ranges and higher measurement accuracies.

[0070] Fig. 7e replaces the conical mirror with a 90° plano-concave axicon, which forms the beam plane through internal reflection at its conical surface and couples it out at its lateral surface, which is also optically polished. The advantage of this arrangement is that there is no need for a transparent mechanical coupling via a glass tube, a glass enclosure, or shading, opaque bracket structures to hold the cone in position. The axicon thus essentially has its own built-in glass tube. Since the cone apex cannot touch the surface of the angled prism, the beam deflection component 7 is formed by two opposing angled prisms with different deflection rates, which ensure that the deflected beam strikes the conical surface of the axicon as centrally as possible.

[0071] Fig. 7f represents a special case. Here, the beam deflection component 7 is identical to the beam plane expansion component 5. This is a cone rotating around the rotation axis, whose symmetry axis is tilted by α / 2 to the rotation axis. At first glance, this represents an extremely simple solution, but is fraught with problems in the stability of the deflection, because wobble errors of the mechanical bearing of the rotation axis are reflected in the measured vertical angle by a factor of 2x. When using an angle prism with, for example, 5° deflection in Fig. 7a, such errors have an effect of approximately tan(5°) = 0.087x, a value that is 23 times better. This variant from Fig. 7f is therefore only preferable if the highest measurement accuracy is not important, but the smallest size and lowest costs are important, such as in the miniaturized integration of the base station into a smartphone or the like.

[0072] Fig. Figure 8 shows a sectional view of the optomechanics of a particularly preferred variant of the base station; this largely follows the configuration of Fig. 7a. The base station works as follows: The laser diode 12 emits a divergent beam, which is converted by the collimator lens 10 into a parallel beam (focused at infinity). This beam strikes an angle prism 7, which is rigidly connected to the hollow shaft 8. The hollow shaft is rotatably mounted by a backlash-free preloaded bearing unit 9. This is driven and rotated by the brushless motor 18. The motor consists of the stator 19 and the magnetic rotor 20, which is connected to the hollow shaft. An encoder disk 21 is mounted on this disk. This, in turn, is scanned by two encoder read heads 22. The signals from these encoder read heads are used to determine the angle of rotation ψ in real time. The beam deflected by the rotating angle prism falls on the conical mirror 5, which forms the tumbling beam plane that exits through the glass tube or glasshouse 38 into the measuring chamber.

[0073] The control unit 23 detects the electrical rotation angle signals of the encoder and generates therefrom a data signal 14 (angle-coded with the aid of angle calibration data), which is forwarded to the driver circuit 13 of the laser diode 12 for modulating the radiation power.

[0074] A block diagram of the control unit is shown in Fig. 9. This consists of a power supply 24 and interfaces for calibration and debugging. The control unit is connected to the motor 18 and the encoder reading heads 22 via encoder and motor electronics 25. The central processing unit 33 regulates the motor speed, manages the user interface 27, as well as a wireless reader 26 for position tags 37, which can be implemented using RFID or NFC technology, for example, and can be attached to the tripods on the stand 36 (see Fig. 15) These position tags store the position of the tripod previously measured, e.g. with static GNSS, thus an entire virtual stringline can be operated with a few base stations that move along with the construction progress, which significantly reduces costs and improves handling by the users.

[0075] This novel sub-approach of the method proposed here can also be advantageously applied to other base stations, as well as total stations, as well as dual-slope lasers, etc. from the prior art.

[0076] The control unit 23 can then insert the read position of the tripod 36 into the angle-coded data signal 14 and thus regularly communicate the position of the tilt compensator 28 to each active target operated in the measuring range, e.g. every few seconds, for further calculation.

[0077] In the control unit 23, an interpolation circuit 31 ensures that the data words encoding angular positions are output at the correctly calibrated encoder positions. The necessary correction data is stored in a calibration memory 32. This allows even encoder disks with poor linearity to be used with high precision. The encoding circuit 31 converts the angular data (even-numbered indices to fixed angular steps), as well as the other auxiliary information, redundancies, and checksums, into an MPPM format suitable for optical data transmission, e.g., a modified MPPM signal with eight symbols (i.e., optical pulses) at 128 positions. This allows the encoding of 40 bits of information per data word.

[0078] In Fig. Figure 10 shows the block diagram of the corresponding active target 3. As the beam plane passes over the receiving collimator 40, the light radiation is focused onto an optical fiber 41 and coupled into it. The receiver 42, which can be implemented as a separate component and, for example, safely mounted inside construction machinery, communicates with the outside world only via the optical fiber 41, e.g., a polymer optical fiber (POF), which can be several meters long. The actual measurement point in this case is the receiving collimator 40 mounted externally on the machine, which offers significant advantages in terms of vibration sensitivity and water resistance. The receiver contains a bandpass filter 43 for suppressing optical interference, typically a few nanometers wide in the wavelength transmission range. The filtered optical received signal 44 then falls onto the receiving element 45.This is typically an avalanche photodiode (APD) or a linearly operated silicon photomultiplier. Its bias voltage is controlled by the computing unit 53. The electrical signal of the receiving element is fed to a signal conditioning circuit 48 (e.g., TIA with analog optimal filter). Its output signal is converted by a high-speed ADC 49 into a data stream 50, which is fed to a digital preprocessing and compression circuit 51, which removes unnecessary signals such as interference and noise from the received data stream and feeds the computing unit only a data stream that is necessary for further processing and can be handled by it. The compressor 51 could also be dispensed with if very high computing power is available in the computing unit. The introduction of a compressor 51 (e.g.,The use of a FPGA (implemented by an FPGA) has proven advantageous for low power consumption. This can be reduced to approximately 1 / 10, allowing active targets in the form of a fully integrated handheld receiver (preferably without a fiber optic cable) with battery power.

[0079] Furthermore, the receiver and thus the active target is equipped with communication interfaces 54, as well as a radio connection, e.g. via WLAN, in order to communicate with other active targets if necessary and to pass on the calculated position information.

[0080] In Fig. 11 further details of the data protocol for modulating the optoelectronic beam transmitting element, here a laser diode, are disclosed.

[0081] Fig. Figure 11a shows the temporal evolution of the angle-coded data signal 14 over time. For a typical, preferred implementation, a 40-bit data word 15 lasts approximately 2.5 µs and consists of a start symbol (start pulse) for synchronization, as well as 8 data symbols (data pulses) at 128 codable positions. The start symbol is in Fig. 11a is encoded as a stronger pulse (bilevel coding) to make it easier to distinguish during decoding. As in Fig. As shown in Figure 11b, the start symbol 16 can also be encoded as a double pulse at a distance that does not occur in the rest of the data word. With sufficient computing power, synchronization can then be achieved using autocorrelation to this time interval.

[0082] In Fig. 11c, the sequence of several different angle-coded data words 15 is shown. The data words contain the exact angular position ψ present at the times of the start pulses, in this case four consecutive angle values ​​ψ n-1 to ψ n+2 .

[0083] When sweeping over the active target at a very large distance, these are received with an envelope 47, which represents the time-varying coupling between the beam plane and the receiving collimator during the sweep.

[0084] For an accurate angle calculation, the angle must be interpolated, which at exactly t c , i.e., at the temporal center of the envelope. The envelope was not available, but the analog data stream 46 deformed by it was.

[0085] If one defines its temporal focus along reasonable boundaries t start are stopIf you want to determine this, you can calculate the discrete approximation using the following formula: tc=∫tstarttendt⋅P(t)dt∫tstarttendP(t)dt

[0086] Although this value depends slightly on the data content of the data words, it allows for a temporal center of gravity determination that is significantly better than 1 / 10 of an angular step of the data words, typically better than 2 arc seconds. With an aperture angle of +-5° of the base station, theoretical vertical angular resolutions of 0.17 arc seconds are possible.

[0087] Using the decoded rotation angle ψ +1 and ψ n , which were transmitted near the temporal center of gravity and are decodable, the angle of rotation that was applied to the temporal center of gravity of the beam plane can be calculated as follows: ψc=ψn+ψn+1−ψntn+1−tn⋅(tc−tn)

[0088] This angle of rotation can then be used to calculate the direction angles according to formulas (i) and (ii).

[0089] It should be emphasized again here that the modulation does not have to be limited to PPM methods; Manchester coding, PSK, QPSK, QAM and many other modulation methods are also conceivable.

[0090] Fig. Figure 14 shows the attachment of the active targets 3 to the rolling element 69 of a road roller and to the kinematic center of the paving screed 70 of a road paver. The hot asphalt pavement 68 is removed by the paving screed at a predetermined height, which is specified by the reference variable "virtual stringline." With the road roller, the slump and thus indirectly also a measure of the compaction of the road surface can be determined by means of the active target during several passes over the still hot pavement and displayed to the machine operator. When attached to the paving screed, two active targets are attached as an example, which allow the absolute height to be determined.

[0091] Fig. Figure 15 shows two base stations 2a and 2b, as well as a stationary target, which span a virtual stringline 64 by interpolation at the virtual laser planes 65a and 65b for base station 2a, and 65c and 65d for base station 2b. The stationary target serves as an additional reference point.

[0092] In Fig.Figure 16 shows a top view of a road construction site 67 with a road paver 61 with an active target 3 mounted on its screed, using the method for height and position determination with the aid of a virtual stringline 64. If additional information such as intersection points of the directional angles are blended with the planned course of the vehicle's travel or odometers are calculated with them, an optional absolute position determination can be dispensed with, at least for height control, and the necessary control parameters for interpolation and smoothing of the reference variable at the transition points of the segments can still be determined with sufficient accuracy.

[0093] The measuring arrangement can be used extremely advantageously in many other applications using the method for guiding vehicles described in this patent specification. For example, the measuring arrangement can be used to replace, among other things, dual-inclination lasers for construction site operations. A particular advantage is that the inclination of the virtual laser plane can be adjusted on the active target, and that the inclination axes can also be set as desired using this. It is even conceivable for different users to work with different inclination planes. It is also possible to level conical surfaces, such as those for poured material cones, which is otherwise only possible with expensive special lasers. It is also possible, similar to multi-cross lasers, to project several virtual planes that are perpendicular to one another and to align these with the active target without having to mechanically rotate the base station.These properties are also very advantageous for industrial measurement when aligning machines and shafts.

[0094] The measuring arrangement can also be used for internal position control of the segments in tunnel boring machines or as a core component for innovative pipe construction lasers, as well as for deformation measurements in monitoring applications.

Claims

[1] Measuring arrangement (1) for the optical or quasi-optical determination of the position or orientation of at least one object, comprising at least one base station (2) and at least one active target (3) spatially fixed to the object in the detection range of the base station (2), characterized by that the base station (2) is designed such that it generates a wobbling beam plane (4), during the wobbling movement of which the normal of the beam plane rotates with a rotation angle known at all times about an axis of rotation (18) inclined relative to the normal by a predefined, largely constant angle of inclination, wherein the active target (3) is hit by the beam plane at least twice per rotation of the normal. [2] Measuring arrangement (1) according to claim 1, characterized byin that it is designed to calculate at least one directional angle related to the polar coordinate system of the base station (2) from the angular positions of the rotation of the normal about the axis of rotation (18) which are assumed at those times at which the active target (3) is hit by the beam plane (4). [3] Measuring arrangement (1) according to claim 1, characterized by that the active target (3) is designed to calculate at least one vertical angle with respect to the polar coordinate system of the base station (2). [4] Measuring arrangement (1) according to one of the preceding claims, characterized by that the active target (3) is designed to calculate at least one horizontal angle with respect to the polar coordinate system of the base station (2). [5] Measuring arrangement (1) according to one of the preceding claims, characterized by that the base station (2) contains a rotating beam deflection component. [6] Measuring arrangement (1) according to one of the preceding claims, characterized by that the base station (2) contains a beam plane expansion component (5). [7] Measuring arrangement (1) according to one of the preceding claims, characterized by that the base station (2) contains an optoelectronic beam transmitting element (12) and is designed to collimate its radiation, to deflect it by the rotating beam deflection component (7) and to expand it to the tumbling beam plane (4) by the beam plane expansion component (5). [8] Measuring arrangement (1) according to the preceding claim, characterized by that a means for modulating the optoelectronic beam transmitting element (12) with an angle-coded data signal is present in the base station (2). [9] Measuring arrangement (1) according to the preceding claim, characterized by that it is designed to transmit additional auxiliary data in addition to the angle data. [10] Measuring arrangement (1) according to the preceding claim, characterized by that it is designed to transmit the position of an inclination compensator (28) in the base station (2) as auxiliary data. [11] Measuring arrangement (1) according to the preceding claim, characterized by that the active target (3) is equipped to determine the angular position of the rotation of the normal of the beam plane (4) about the axis of rotation (18) from the radiation of the beam plane (4) modulated with the angle-coded data signal and the auxiliary data at the time of impact and a temporal center of gravity calculation. [12] Method for guiding a vehicle with a measuring arrangement according to one of the preceding claims, wherein the at least one active target (3) is fixedly related to the vehicle and falls within the detection range of the base station, at least one further active target (3) is used stationary, by the connecting line between the base station (2) and the stationary active target (3) is spanned by a segment of a virtual guide wire and a virtual plane with a predefined transverse inclination is spanned and the vehicle is guided in its working height with reference to the directional angles obtained with the active targets (3) relative to the base station (2). [13] Method according to the preceding claim, characterized by that a virtual guide wire is formed from a chain of segments, with base stations (2) and stationary active targets (3) alternating. [14] Method according to the preceding claim, characterized bythat additional information is used to determine necessary control parameters for interpolation and smoothing of the reference variable at the transition points of the segments, preferably by intersecting points of the directional angles with the planned course of the vehicle's journey or by calculating odometers.

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