Measuring device and method

Abstract

To provide an inexpensive measuring system with high accuracy at the same time.SOLUTION: A base station 2 is configured for a wobbling motion of a planar beam 4, by the wobbling motion, a posture of a normal 6 of the planar beam 4 is changed in a known way such that orientations of the normal 6 occur repeatedly. The normal 6 of the planar beam 4 can cyclically repeat its posture. A measuring device 1 for the base station 2 of this type and at least one remote station 3 belonging to the base station, is also provided. A method for guiding a mobile object, in particular a vehicle, is provided. Here, the base station 2 and at least one active remote station 3 permanently associated with the mobile object are used. They form a transmitter, a receiver, and the measuring device together.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention is directed to the generic claims and therefore deals with measurements. [Background technology]

[0002] Measuring devices which can measure the position and / or orientation of an object and / or its individual coordinates relative to a base station are applied in many fields, for example in the detection of real objects for the creation of virtual realities, in industrial and construction surveying, construction machine control, etc. For this purpose many devices for measuring or surveying are known.

[0003] Therefore, many different technologies have been developed, such as tachometers, laser trackers, rotating lasers, real-time kinematic GNSS receivers, etc. Some of these allow simultaneous use at many measurement locations by relatively cheap devices, e.g. by multiple remote stations relative to one base station, but have a series of problems, such as excessively low measurement accuracy, multipath reception and shadowing, e.g. in street canyons, as well as the availability of correction services and satellite systems.

[0004] Therefore, in many applications, a proven approach is to install a central base station that emits a rotating or fan-shaped beam. With a suitable beam receiver, the position of the receiver relative to the base station can be deduced. In principle, for example, a passive retroreflector could be used to send a beam back from the receiver to the base, where it could be determined from where this beam was reflected. However, so-called active receivers are easier to use and are now widely used in surveying. In active receivers, a photosensitive element can generate and evaluate an electrical signal in response to the reception of light. Here, the signature with which the beam is detected at the beam receiver is related on the one hand to the manner in which the base station emits the beam and on the other hand to the manner in which the beam receiver is constructed. For example, the beam receiver can be equipped with an elongated or point-shaped photosensitive element and the base station can emit light as a fan-shaped or single beam, with constant intensity or with temporal modulation. It should be mentioned that the beam can be visible or invisible and, in some cases, beams in the high frequency range can be used. For simplicity, unless otherwise clear, reference will generally be made herein to position determination being performed "optically" or at least "quasi-optically", even if invisible or radio frequency radiation is sometimes used.

[0005] In the described systems with a central base station, there are already a number of approaches to reduce costs and increase accuracy as well as availability, which are exemplarily shown in the base station known from the prior art shown in Figures 1a to 1d.

[0006] FIG. 1a shows a base station with three fan beams emanating from a rotating base as disclosed in the applicant's US7394527 and US5767960, which enable a wirelessly or wired synchronized active remote station, i.e. an illuminated active target, to calculate the spacing, height and horizontal angle of the active target in cylindrical coordinates relative to the base station from the time sequence of incidence of the three fan beams on the active target.

[0007] Figure 1b shows the base station of EP1434029 with three areal beams emanating from the centre of rotation, which, by means of suitable active targets, makes it possible to calculate the horizontal and vertical angles in the polar coordinate system of the base station.

[0008] FIG. 1c shows a prior art device according to US Pat. No. 4,441,809, the characteristics of which substantially correspond to those of FIG. 1a, but in which at least two active targets are required to determine multiple elevation angles.

[0009] FIG. 1d similarly shows the base station of US5110202 with two rotating fan beams, which allows the active target to calculate horizontal and vertical angles in the base station's polar coordinate system.

[0010] The prior art approaches shown in Fig. 1 have in common that they are based on rotating laser optics, which emit at least two to three fan beams, making it possible to determine up to two directional angles with respect to an active target. For this purpose, time measurements of the incidence times of the individual fan beams are used. Now, these approaches also make it possible, at least in principle, to provide an almost arbitrary number of virtual (laser) planes across the measurement space centered on the base station, with the measured vertical and horizontal angles, i.e. to measure at many heights.

[0011] However, these known devices and the required receivers are often undesirably complex in construction, especially if high accuracy is to be obtained. That is to say, the accuracy of such optical devices is determined, among other things, by the accuracy with which the light emission through the base is performed. Here, among other things, but not exclusively, the accuracy with which the mechanical construction is performed is involved, which leads to high costs for high-accuracy base stations. With regard to the range, it should be noted that in many cases the beam should be well visible. This allows the receiver to be relatively easily placed in the beam path. Furthermore, it should be noted that in many cases the beam is emitted at a height close to eye level. Therefore, for safety reasons, the beam energy should be limited in order to provide eye safety. This also reduces the range.

[0012] Moreover, the illustrated approach is based, inter alia, on the fact that two or more fan beams must be guided through different (cylindrical) optics, which in principle have different and non-cancelling imaging errors. Thus, in particular the required flatness or parallelism of the fan beams is extremely critical, so that a high-precision determination of the vertical angle is not possible without a laborious, costly and time-consuming factory calibration in several degrees of freedom. Furthermore, the synchronization between the active receiver and the base station is often simply loose or completely missing, which likewise places high demands on the parallelism of the rotating laser head if high angular accuracy is desired. Typically, to obtain angular accuracy of a few arc seconds for the vertical and horizontal angles, parallelism values ​​of about 0.001% to 0.0001% are required. Due to these requirements, the base station must rely on expensive and fragile bottom friction bearings and large flywheel masses, which reduces robustness and calls into question its practical suitability for many applications. In particular, base stations become larger and heavier, causing system prices and overall costs to users over their lifetime to rise sharply.

[0013] It would therefore be desirable to enable improvements here, especially since at least the approach known from the prior art shown in figures 1b and 1d remains very popular with users in the fields of construction machine control and industrial surveying.

[0014] Therefore, automatic tracking distance measuring devices have already been developed for specific applications, in which individual remote stations are tracked by a base station. These individual remote stations can be passive retroreflectors or active receivers, or they can be active transmitters, in which case the base station is explicitly configured to receive radiation from the remote stations. Such systems, often known as laser trackers for industrial surveying or robotic tachometers for land surveying, are still very popular, but they are expensive and have the disadvantage that they only allow tracking of individual targets on a per base basis.

[0015] In certain applications, for example the advantageously global, preferably even autonomous, road paving column, i.e. a series of road finishers and multiple roller construction machine control, this results in almost prohibitive costs, since an own base station must be provided for each object or measuring point thereon to be tracked or surveyed.

[0016] In the field of construction machine control, it is often necessary not only to measure the position or location, but also to control the height precisely. This is required, for example, but not exclusively, in road construction, where, for example, the laying height of the road surface or the thickness of the road surface layer should be controlled. Most of the systems used for this consist of a rotating laser and a so-called machine receiver, i.e. a line-like receiver on the road construction machine, adapted to the rotating laser, which allows for precise height control, but is tied to only one laser plane, which can be a major drawback especially in rough terrain.

[0017] Thus, traditionally, guide wires or reference lines have often been used in rough terrain, but their installation is just as laborious. Approaches that use base stations, especially those with integrated receivers, to replace the otherwise real reference lines with virtual guide lines typically still require a lot of equipment labor.

[0018] Thus, for example, EP 2 998 699 proposes a method for guidance of the laying height and layer thickness control of a road construction machine, the disclosure content of which is incorporated by reference. This method, known from the prior art, is illustrated in a simplified manner with reference to FIG. 13.

[0019] In this known method, a station is used that can be used simultaneously as a base station and as a receiver of radiation of another station, i.e. a rotating laser transceiver. To control the installation height of the road finisher, the otherwise commonly used guide wire is replaced by a number of mutually leveling rotating laser transceivers 66a-66g (TRX) arranged in a chain. This is done in that, for each segment, a virtual guide wire is defined along the road 67 with reference to the laser plane 72 generated by the base station. The rotating laser transceivers act as interpolation points for this guide wire. Interpolation and possibly smoothing between these interpolation points increases their spacing, which should somewhat reduce the calibration effort for a given section.

[0020] Such a system would seem to amortize its price quickly, since it should be less expensive than the cost for a surveyor to calibrate a section several kilometers long using conventional guide wires, but these are in any case particularly laborious to construct, since even in the case of interpolation many rotating laser transceivers leveled against each other are required.

[0021] Moreover, this known system has other drawbacks, such as limitations in the height measurement range, which are significantly reduced by the described chain arrangement but are not completely eliminated. This is illustrated in FIG. 12, where a typical constellation of a hot asphalt installation with two machines is shown.

[0022] It is clear that reception of the laser surface on rough terrain takes a very long time and therefore in principle requires a particularly costly laser receiver line on road construction machines. In this regard, reference is made in passing to, in particular, the applicant's US Patent Application Publication No. 2018 / 0259332, which is also fully incorporated by reference into the present application. However, the length of these devices can lead to measurement inaccuracies when the machine vibrates, for example in the case of use in the screed of a road finisher or in the suspension of the rolling bodies of a road roller, which requires a compromise between flexibility, cost and availability.

[0023] Another drawback of this known prior art is that each transceiver 66 can only emit one laser plane and the radiation is emitted only in one plane, so that for each interpolation point of the virtual guide line of the prior art a unique transceiver must be provided. This transceiver simultaneously includes both the base station and the active target. Therefore, these devices are limited to a specific purpose of use and are hardly suitable for universal application.

[0024] It would be advantageous to be able to provide an inexpensive measurement system, especially with a simultaneous high degree of accuracy.

[0025] It would also be advantageous to be able to provide a virtual guide wire ("string line") inexpensively. It would further be advantageous to be able to use a base station that could be used for a wider range of applications. It would further be advantageous to impose fewer constraints on the height measurement range than known in the prior art.

[0026] It would also be advantageous, inter alia, to further reduce system costs, to measurement devices and methods that could enable interpolation points of a virtual string line without the need for particularly expensive base stations.

[0027] It would also be desirable to provide improved measurement arrangements and / or methods for optical or quasi-optical position determination.

[0028] It would be desirable to obtain, at least in part, at least one of the advantages outlined above. Summary of the Invention [Problem to be solved by the invention]

[0029] The object of the present invention is to provide something new for commercial applications. [Means for solving the problem]

[0030] The above-mentioned problem is solved by the independent claims.

[0031] Some advantageous embodiments are set forth in the dependent claims. Further advantageous embodiments as well as further inventive solutions are set forth in the specification.

[0032] That is, in a first basic consideration of the invention, a base station for measurement is presented, where a measurement beam is emitted onto a surface, where the base station is configured for a wobbling movement of the surface beam in such a way that the position of the normal of the surface beam is changed in a known manner and in such a way that the orientation of this normal occurs repeatedly.

[0033] The first basic realization is therefore that a controlled, deliberately set wobble movement of the surface beam in a known manner makes it possible to determine the vertical angle or, with further information, the height can be determined particularly easily: for example, if a base station emits a beam which is detected by a receiver, the height of the receiver relative to the height of the base station can be easily established.

[0034] To understand this, let us assume that the planar beam stands fixed, i.e., its orientation does not change. In such a case, a receiver currently located within the planar beam, i.e., currently illuminated by the beam extended to the surface, will continue to be located within the planar beam as well.

[0035] In contrast, if the surface beam wobbles, this causes the beam to gradually change its height at the location of the receiver in accordance with the wobble motion. More precisely, the beam moves up and down between a maximum height and a minimum height at a given location away from the base station, i.e. in accordance with the wobble motion. If, for the sake of clarity, we assume a periodic wobble motion and further assume that the beam receiver is fixedly located at a given location away from the base station at a height between the maximum and minimum heights reached by the surface beam, then during one wobble cycle the surface beam sweeps the receiver twice: once when the surface beam descends from above to below and reaches the receiver height, and once when the surface beam ascends from below to above and reaches the receiver height. If the receiver height is very close to the maximum height, after the first sweep is observed on the rise, it takes only a short time for the surface beam descending again to reach the receiver for the second time. The same is true if the receiver height is very close to the minimum height and the descending surface beam has just swept the receiver height for the first time. Nevertheless, the surface beam, which initially descends to its minimum height, only needs a short time to rise to the receiver again. On the other hand, if the receiver height is approximately halfway between the minimum and maximum heights that the surface beam can reach at a given distance, it will take a correspondingly longer time for the receiver to be swept again, given the same wobble speed. Therefore, if the wobble behavior and the distance from the base station are known, the receiver height can be inferred from the time interval between the sweeps.

[0036] It should be pointed out that if the receiver is repeatedly swept at a given height under a periodic wobble motion, two different intervals may occur between the two sweeps. The first interval corresponds to the time between the sweep when the areal beam moves from top to bottom and the sweep when it moves from bottom to top, and the second interval corresponds to the time between the sweep when it moves from bottom to top and the sweep when it moves from top to bottom. The two intervals together correspond to a wobble period. However, the same combination of intervals may be observed both near the height maximum and near the minimum. This may sometimes lead to an ambiguity, when it is not clear whether the areal beam is tilted up or down precisely due to the wobble motion, but this can be resolved in various ways.

[0037] It will be further apparent that the maximum height that the beam can reach for a given wobble-induced tilt of the areal beam is related to the spacing from the base station, where the time spacing is related to how close the receiver height is to the minimum or maximum height that the beam can reach in this spacing for a given wobble-induced tilt of the areal beam.

[0038] Thus, if the distance from the receiver to the base station is not known, then for example the vertical angle may already be obtained as a usable measurement. However, it is possible and advantageous to take additional measures to determine the distance from the receiver to the base station and / or to resolve ambiguities in the height determination. There are various possibilities for this.

[0039] In some cases, to obtain clarity regarding height, the measurement space can be restricted, for example, to a half-space whose coordinate center of the base station passes through its dividing surface, so that, for example, measurements are only performed at heights above the horizon or only at heights below the horizon. It can also be determined at the receiver, for example by using two photosensitive elements, whether a wobbling movement at that location leads exactly to a rise or a fall of the surface beam. It should be pointed out here that the clarity once obtained is maintained as long as it is tracked how the active remote station moves relative to the base. This is sufficient to guarantee clarity in the long term. This tracking is particularly advantageous when it must be taken into account that ambiguities cannot always be resolved even with a large number of photosensitive elements, for example due to temporary shadowing of one or more photosensitive elements of the active remote station.

[0040] Here, the photosensitive elements are advantageously arranged at a known distance from each other, so that in principle both photosensitive elements are swept apart and overlap each other. In such a case, it is first identified from the series of sweeps whether the upper photosensitive element is swept first and then the lower one, or vice versa. That is, from the course of reception events, it can be identified whether the surface beam is currently rising or falling due to a wobble at the receiver's location. Furthermore, the distance between the receiver and the base station can also be determined here. It should be mentioned that the effort in terms of equipment for moving two sufficiently large photosensitive elements in the optical receiver and the time for evaluating the signature of these receivers are very short. Moreover, such receivers can be constructed to withstand vibrations, so that even in the case of strong vibrations, such as those occurring in road construction machines, uncontrollable vibrations do not interfere.

[0041] In principle, the base station emits radiation and the remote station is configured as a receiver for receiving the radiation emitted from the base station, the receiver being an active remote station, typically provided with a photoelectronic element such as a photodiode, which generates an electrical signal in response to the incidence of radiation, which is in principle further processed in the active remote station, i.e. for example signal conditioning, so that in response to the analog received signal a digital signal is determined, and in response to this digital signal other variables, such as for example an angle or a coordinate relative to the base station, are calculated.

[0042] The term "light beam" emitted by the base station here does not simply refer to visible light radiation: conventional laser diodes, solid-state lasers, LEDs emitting in the visible or invisible, especially in the infrared, as well as array arrangements of individually or jointly drivable elements sharing the same downstream optics such as collimator optics, and in the case of the quasi-optical wavelength range, Gunn diodes and other HF emitters are mentioned here as suitable sources of such radiation that are encompassed by the term "light beam".

[0043] The emitted radiation passes through a surface, which wobbles in accordance with the invention. In some cases, due to inaccuracies or wear of the rolling bearings, etc., a kind of wobbling motion can be observed in known base stations with rotating beams, but it should be indicated that this is not a wobbling motion, specifically, a known wobbling motion, in which there are parameters according to which the current orientation of the normal is obtained. Unlike the wobbling motion, in a wobbling motion the orientation of the normal of the surface beam does not change in a known and controlled manner, much less in such a way that the orientation of the normal is known and repeated.

[0044] It should also be pointed out that the wobbling movement of the present invention can in principle result in a considerable change in the inclination of the surface beam: for an averagely horizontal surface beam, it is clear that the wobbling movement results in an inclination of at least ±2.5°, preferably ±5°, more preferably at least ±10°, and particularly preferably at least ±15° with respect to the horizontal, each in relation to a complete circle of 360°.

[0045] It should be emphasized that a single surface beam emitted by a base station with a staggered beam, with radiation emitted as a flat profile beam, a planar beam or a fan beam in the optical or quasi-optical wavelength spectrum, is already sufficient to determine two orientation angles relative to the base station, namely the vertical angle λ (lambda) and the horizontal angle ψ (psi) during the sweep of an active remote station. In this respect, it should also be mentioned that in the case of stationary or nearly stationary remote stations, the normal can repeatedly assume the same position, so that the values ​​can be averaged, thereby increasing the accuracy.

[0046] There are various ways in which the orientation of the surface beam normal can be changed in a known and controlled manner. For example, a complete rotation or a back and forth movement between two end points (in a scanning or oscillating manner) can be set up. A scanning back and forth movement has the advantage that a certain area is swept more frequently. On the other hand, a complete rotation is in principle easier to realize structurally.

[0047] In principle, it is also possible that the beam path passes through the same optical components of the base station under two beam passes of the rotation or scanning movement, so that the otherwise particularly relevant errors largely cancel each other out, in particular the linearity errors with respect to the measurement of the vertical angle. A quick one-dimensional calibration of the vertical angle offset is therefore sufficient to allow the vertical angle to be detected with an accuracy even down to the sub-arc second range.

[0048] It is not essential to use an active receiver as an active remote station, but it should be emphasized that in some cases an active remote station can also be active by itself emitting a beam. In this case, the base receives radiation only from the wobbling surface, for example by connecting a suitable receiving optics in front of the photosensitive element. That is to say, where in this specification optoelectronic beam transmitting elements are otherwise mentioned, in the case of such a reversal between the transmitter and the receiver, optoelectronic beam receiving elements such as photodiodes, APDs, SiPMs, detector arrays, CCDs, etc. can be provided instead, and vice versa. In this case, this causes the otherwise normal beam direction to be reversed. The surface beam represents the directional characteristics of the light beam reception, not the directional characteristics of the emitted measurement radiation. This is obviously possible not only for base stations, but also for remote stations that are in principle configured as receivers. This is not discussed further in all the following places, but has advantages in this respect, since the radiation can be directed precisely or roughly to the base, which reduces the risk to persons at a given beam intensity as required.

[0049] It may furthermore be provided that in the base station both the optoelectronic beam transmitting element and the optoelectronic beam receiving element are simultaneously arranged at the focus of the collimation optics, for example using a polarizing beam splitter with a λ / 4 plate. This allows the base station to transmit and receive optical radiation simultaneously, which allows for directional measurements at highly reflective passive targets, for example corner / cube reflectors (cat's eye) as used in total stations. Furthermore, pulse time measurements are possible to determine a complete set of 3D coordinates. In such cases too, the surface beam is staggered. This is already considered novel in itself, since it allows several base stations to, for example, calibrate themselves to one another and also to perform 3D measurements comparable to robotic tachometers. The advantage over previously known base station transceivers is that here the much simpler optomechanics only require one precise axis of rotation, as opposed to two axes of rotation in conventional tachometers. As will be explained further hereinafter, the utility of such a device for segment chains forming guide lines is expressly disclosed as being particularly advantageous and inexpensive, and is likewise considered to be novel in itself.

[0050] It should be mentioned that equipping a base station for radiation reception and an active remote station for beam emission, in each case so that only radiation from a specific direction is received, is also considered patentable per se, especially when operation is performed on a wobbling surface, where the base station in this case has wobbling reception properties.

[0051] That is, as is clear from the above description, a measuring device can be provided, in particular for optical or quasi-optical position determination, which, for an object whose position or attitude is to be determined, has at least one active target which is spatially fixedly associated with this object and at least one base station, in which the active target is present in the area of ​​the base station which can be detected in the measurement, and in which the base station generates a fluctuating surface beam.

[0052] It should also be explained that the term surface or surface beam refers to a wide variety of beam arrangements. Thus, for example, a planar beam profile may be used in the present invention, which is, for example, a flat plane that is preferably substantially undistorted, i.e. except for imaging and alignment errors. However, conical surfaces with circular, elliptical or slightly wavy basic profiles may be used in the present invention for the conical mirror described below or the total reflection conical depression of the axicon described below, and reference is also made to fan beams or multiple fan beams, which are, for example, coplanar multiple fan beams caused by shadowing. Reference is also made to planar beams of the above type that are distorted by imaging and alignment errors. Despite this broad interpretation of the term, in particular when mathematical formulas are presented, an ideal flat surface is assumed in order to facilitate the understanding of the presented mathematical formulas. However, it should be mentioned in this respect that planar beam profiles, fan-shaped beams or (if freedom from wobble without further superposition is envisaged) beams circulating on the surface are particularly advantageous, this also applies in particular when the advantageous profile is distorted by imaging and / or alignment errors.

[0053] The wobbling movement is advantageously realized and defined by the end of the normal to the surface beam cycling around an axis that is not parallel to this normal, in particular cycling at a constant or substantially constant tilt angle relative to the non-parallel axis that is always known. Here, the phase of the rotation of the surface beam normal about the non-parallel axis is also always known, and the surface beam is incident on the active remote station, i.e. essentially active target, at least twice per periodic rotation of the normal, in particular at a normal phase angle of ψ1 and at a normal phase angle of ψ2 (it should be noted that these phase angles are also referred to hereinafter as rotation angles or angular positions). As is known from gyroscopes, the normal follows a kind of precession.

[0054] On the one hand, in principle, the non-parallel axes generally stand vertically, which, on average, causes the surface beam to wobble about a horizontal plane. The vertical axis can be the axis of rotation of an optical element, i.e. a rotating beam deflection component for the radiation emitted by the base, if the wobbling motion is realized as a periodic wobbling motion by rotating this optical element.

[0055] However, it should be mentioned that it is not necessary to orient the non-parallel axes exactly vertically. In particular, it is possible to compensate for non-precisely vertical orientations of the non-parallel axes, which in particular avoids the need for laborious installation and also helps to avoid errors during the measurement, especially if the installed base itself gradually tilts during the measurement, for example because the ground is too soft. In other words, it should be emphasized in this respect that, although the non-parallel axes usually stand substantially vertically, their orientation is not necessarily limited to such an orientation.

[0056] From the above description, it is understood that in the measuring device of the present invention, at least two phase angles or at least two time points at which the active remote station is swept when the surface beam normal rotates around the non-parallel axes can be used to calculate at least one direction angle with respect to the polar coordinate system of the base station. It may be advantageous for the active remote station, i.e. the active target, to be configured to calculate at least one vertical direction angle λ (lambda) with respect to the polar coordinate system of the base station. Furthermore, it is clear that the active target may be configured to calculate at least one horizontal direction angle ψ (psi) with respect to the polar coordinate system of the base station.

[0057] From the above description, it can be seen that the surface beam normal can easily repeat its own orientation, by periodically passing through its own orientation. In an advantageous embodiment, it is therefore also proposed to configure the base station to generate a wobbling motion of the surface beam, such that the surface beam normal periodically repeats its own orientation. A particularly advantageous periodic motion can be realized by a precession-like rotation of the surface beam normal around a generally vertical axis.

[0058] Here, in order to realize a wobbling surface beam movement particularly easily, the base station only needs to include a rotating beam deflection component. Examples for this are a rotating transmissive refractive angle prism, a rotating mirror arranged at an angle to the vertical axis or to the axis of rotation, an axicon or a conical optic, which can be formed as a conically ground lens that images a point source onto a line along the optical lens axis or converts a laser beam into a ring, as well as any other rotatable arrangement of a plurality of optical components that can rotate and deflect a collimated beam around its propagation direction by an angle a. It is obviously advantageous for the base station to include a rotating beam deflection component, since it can be easily implemented using such elements.

[0059] Furthermore, since this is particularly well realized structurally, it is advantageous if the base station is designed for use with an active receiver and the wobbling movement is generated in such a way that the normal of the surface beam is not parallel to this normal, but always rotates around a rotation axis standing at a predefined, at least substantially constant, inclination angle to this normal, with a known rotation angle, and the surface beam is incident on the active receiver at least twice per rotation of the normal.

[0060] As mentioned above, many beam profiles are possible. To obtain these from conventional beam sources such as laser diodes, solid-state lasers or LEDs, it is advantageous to use beam expansion components. It is therefore advantageous for the base station to have a beam expansion component or beam expansion means, for example a component that expands the beam into a surface beam. It is pointed out that in some cases the beam can be expanded to form one or more fans. It is further pointed out that the spatial distribution of the emitted light can be influenced by shadowing, selective absorption, etc.

[0061] The beam expanding element for generating the surface beam can have the form or function of, for example, a conical mirror, which may be configured with any cone angle, preferably 90°. Similarly, the use of an axicon, for example a plano-concave axicon with internal reflection and lateral extraction via the envelope surface, is disclosed, and it is further mentioned that cylindrical optics can also be used, as well as any other combination of suitable optical components.

[0062] It may also be provided that the base station comprises an optoelectronic beam transmitting element, which is followed by an optical element and / or which is integral with the optical element, so that the emitted radiation can be collimated to a certain aperture angle or, preferably, to a spread that is as parallel as possible. Possible for this are laser diodes, solid-state lasers, LEDs, as well as arrays of individually drivable elements sharing the same collimator optics, as well as Gunn diodes or other HF emitters in the case of the quasi-optical wavelength range.

[0063] Similarly, it may be provided that both the optoelectronic beam transmitting element and the optoelectronic beam receiving element are simultaneously brought into the focus of the collimation optics, for example by a polarizing beam splitter with a λ / 4 plate. The base station can thus perform directional measurements on highly reflective passive targets, such as the corner cube reflectors (cat's eye) used in total stations, and can perform pulse transit time measurements in parallel to determine the entire 3D coordinates. The base station can thus perform 3D measurements that can be calibrated, for example, or comparable to a robotic tachometer. But the advantage here is that the much simpler optomechanics only require one precise axis of rotation, as opposed to two axes of rotation in a tachometer.

[0064] More advantageously, the collimated beam is deflected by a rotating beam deflecting component and expanded by an area beam expanding component to form a wobbling area beam.

[0065] As is evident from the above description, in an advantageous embodiment the base station comprises an optoelectronic optical radiation transmitting element and a collimator for said radiation, where further rotating beam deflection elements are provided, which are configured to expand the light emitted from the optoelectronic optical radiation transmitting element in such a way that they form a wobbly surface beam. It is evident that this allows the base station to be constructed particularly easily.

[0066] The example of a surface beam normal circulating around a vertical axis has been presented above. Here, it has been explained that this axis does not necessarily have to be exactly vertical. It has already been pointed out that it is possible to compensate for an attitude that is not exactly vertical. Therefore, advantageously, a tilt compensator is provided in the base station according to the invention. The tilt compensator can mechanically force a horizontal orientation, for example by correcting an incorrect attitude with an actuator, possibly by repeatedly correcting a changing incorrect attitude with an actuator, but it should be pointed out that advantageously only the tilt angle of a structurally defined axis of the base station, for example the rotation axis of a rotating optical component, needs to be detected sufficiently accurately, and the corresponding information is used for the evaluation. The basic tilt of the wobble-free surface beam, i.e. the central orientation of the surface beam, can therefore be compensated in two different ways, i.e. by mechanical orientation on the one hand and by metrological detection and computational compensation on the other hand. It should be mentioned that metrological detection and computational compensation are in principle inexpensive and therefore advantageous both structurally and operationally.

[0067] Furthermore, the base station preferably has means for modulating the optical radiation emitted by the optoelectronic element with a data signal, preferably by an angle-encoding data signal and / or by a data signal encoding other auxiliary data, preferably by a unique identifier (ID or serial number) of the base station and / or by the temperature of the base station, the battery state of the base station, etc., as well as by the attitude of the tilt sensor or tilt compensator. That is, information about the current actual tilt of the surface beam and thus the central orientation can be advantageously placed on the radiation emitted by the base station for modulation. Similarly, the current phase in the cycle of the surface beam normal rotation can be transmitted to the active remote station by the angle-encoding data signal. The particular advantage of transmitting the current phase in the cycle of the surface beam normal rotation, i.e. for example the current rotation angle of a rotating optical system, i.e. a rotating square prism, which generates the wobble of the surface beam by its own rotation, is, in addition to the structural simplification by omitting additional elements for wired or wireless transmission, etc., above all the freedom from latency. In the case of multiple reception, averaging is possible, and it should be pointed out that hereinafter a particularly suitable method for coding the rotation angle information is disclosed. The measuring device is therefore advantageously configured in such a way that means are provided for modulating the optoelectronic beam transmitting elements with a data signal which performs angle coding.

[0068] Thus, the synchronization of the angles between the base station and the active remote station can be obtained not as before (time-offset, simply loose) via separate radio or infrared data transmissions, which are susceptible to interference, but directly by modulation of the radiation of the surface beam with the angle-coded data signal from the base station and optionally with other auxiliary information. This arrangement alone can already reduce the requirement for parallelism of rotation, typically by more than two orders of magnitude, and can eliminate the costly bearing and flywheel masses that would otherwise be required. The transmission of the rotation angle by placing appropriate information on the emitted beam for modulation is also advantageous here and is considered to be novel in itself, i.e. in particular regardless of the wobbling movement of the surface beam. Here, the base station emits a rotating beam or a rotating surface beam or fan, and the current rotation angle during beam reception must be known, in particular in order to determine the coordinates of the measurement beam receiver. Here, the data signal imposed on the emitted radiation for modulation can, for example, encode the current angular position of the rotation axis of the beam deflection component, where the angular position is likewise obtained by an angular encoder coupled to the rotation of the beam deflection component.

[0069] In this respect, it should be clearly pointed out that some aspects of the invention disclosed herein, as claimed or disclosed herein, in particular the optical data transmission via the laser beam with the rotation angle data and / or the transmission of auxiliary information, such as a unique identifier (ID or serial number), also apply advantageously to the laser transceivers of EP 2 998 699 A in general, and likewise to any rotating laser, which thereby allows the determination of the horizontal angle, without the realization of an external synchronization, for example by radio or a separate IR data transmission, or in order to be able to uniquely assign the received laser beam to a laser transmitter.

[0070] From the above description it also becomes clear how it can be advantageous, at least intermittently, to transmit further auxiliary data on the radiation or surface beam in addition to the angle data, in particular for example the orientation, i.e. the attitude, of the tilt sensor or tilt compensator for the subsequent compensation of the tilt of the base station at and through the active remote station, as well as the battery state, temperature, etc., which allows early identification of potentially critical operating states of the base station in case of long-lasting measurements, without the need for any human control at the base station.

[0071] It should be mentioned that the size of the photosensitive elements in the active remote station is typically so large that the sweep of the photosensitive elements and thus the reception of radiation by the base station takes a certain amount of time. This is already the case for photosensitive elements with a very small area, so that it becomes possible to determine the direction angle particularly accurately without special constructional efforts at the active remote station, as long as the active remote station is designed to calculate and determine the phase position of the surface beam normal obtained during the sweep period, i.e. the angular position of its rotation around the rotation axis, taking into account the time center of gravity of the beam reception.

[0072] That is, the phase position of the surface beam normal is typically coded at discrete angular steps, and if radiation coded at these discrete angular steps is received over an extended period of time, it is possible to interpolate between multiple discrete angular steps.

[0073] That is, preferably, an interpolation is performed between a plurality of discrete angle steps transmitted from the base station and received at the active remote station during beam reception, i.e. during the sweep of the active remote station. Alternatively and / or additionally, the beam reception signature can also be evaluated by optimizing a model of a typical beam reception course, for example by means of the LMS method or a correspondingly trained neural network (KI, AI).

[0074] At large distances between the base station and the photosensitive element, the beam reception events are so noisy and / or last so short that in many cases only one angular step can be decoded at the receiver. However, by taking into account the wobble velocity and the envelope curve of the received signal, it is still possible to continue to deduce the phase position of the temporal centroid with sub-sampling accuracy, i.e. much more accurately than the encoded angular step. It is clear that for the corresponding calculations, the wobble velocity does not have to be particularly precisely known, and its temporal variations under the above conditions do not significantly affect the measurement accuracy.

[0075] As is clear from the above description, protection is claimed primarily for the base station. However, protection is also claimed for the measuring device, which includes at least one corresponding base station as described above, as well as at least one associated active remote station. It should be mentioned that in some cases, the active remote station may be arranged in another base station, as described, without particularly high constructional effort. However, in other cases and / or additionally, the active remote station may be realized by an active receiver. Here, an active receiver is considered when there are active electronic elements or active electronic circuits or data evaluation units, etc. in it. It should be mentioned that the inventive measuring system with a base station can address several active remote stations, and accordingly several active remote stations can belong to the measuring system. In particular, at least an active remote station provided on the mobile unit and an active remote station arranged on the stationary position may be provided, for example to define a virtual guide line.

[0076] As already explained, by appropriately configuring the active remote station, it is also possible to easily resolve ambiguities in the height determination, in particular by using vertically spaced photosensitive elements, in which case the distance between the active remote station, such as an active optical receiver as an active target, and the base station can be determined at the same time, if the distance between the photosensitive elements used therein is known.

[0077] An advantageous embodiment of the measurement beam receiver therefore provides that it has at least two mutually spaced photosensitive elements which are arranged at different heights in operation, and that the measurement beam receiver is configured to resolve the ambiguity of the height determination from the time signature of the sweep of the photosensitive elements, and advantageously also to determine the distance from the base station. It should likewise be mentioned that in the remote station emitting radiation, at least two beam sources can be provided correspondingly spaced from each other.

[0078] In particular, it will become apparent that in connection with the advantageous embodiments, active remote stations, such as active measurement beam receivers, are specially adapted for use with the base stations of the present invention.

[0079] Protection is therefore also claimed for a measurement beam receiver, which may be configured to receive a light beam from a base station as disclosed herein or as described above, and in particular may be configured to calculate at least one angle in relation to a polar coordinate system of the base station in response to a repeated detection of a wobbling surface beam. This calculation is preferably performed by determining the time of detection and / or by determining at least two angular positions of the surface beam normal, which rotate due to the wobbling of the surface beam, at the time of detection. It should be mentioned that in principle, using the base station of the invention and the associated active remote station, it is possible to determine the complete position and possibly the attitude of the active remote station relative to the base station, and any coordinates can also be determined unambiguously. In this regard, it is not necessary to refer to particularly straightforward cylindrical or spherical coordinates with the base station as the origin for the explanation.

[0080] In the measurement beam receiver of the present invention, as is evident from the above description, the measurement beam receiver is advantageously configured to decode radiation modulated with an angle-encoded data signal and possibly auxiliary data to determine an angular position and / or the measurement beam receiver is configured to calculate at least one vertical angle with respect to a polar coordinate system of the base station.

[0081] Further advantageously, the measurement beam receiver is adapted to calculate at least one horizontal angle with respect to a polar coordinate system of the base station, i.e. typically signal conditioning and / or digital data processing stages are provided.

[0082] In order to determine the direction angle with high accuracy, the active remote station, i.e. the active target, can be configured to determine the angular position of the rotation of the normal of the surface beam around the rotation axis from the radiation of the surface beam modulated with an angle-encoded data signal or, if appropriate, auxiliary data at the time of incidence, as well as calculation of the temporal center of gravity of the beam reception for interpolation between the transmitted discrete angle steps.

[0083] A particularly advantageous and typical application of the measurement system, emission based and / or measurement beam receiver of the invention is the guidance of moving objects, in particular vehicles, for example autonomous vehicles.

[0084] Protection is therefore also claimed for a method for guiding a moving object, in particular a vehicle, in which a base station emitting radiation and at least one measurement beam receiver for that radiation are used, which is fixedly associated with the moving object, where at least one other measurement beam receiver is installed stationarily, a virtual connection line between the base station and the other, stationarily installed measurement beam receiver is determined, and then guidance data for guiding the moving object are determined with reference to the radiation detection by the measurement beam receiver fixedly associated with the moving object and the virtual connection line. This is preferably done by determining a plane, in which a connection line lies between the base station and the stationary measurement beam receiver, which additionally has a defined lateral inclination. Furthermore preferably, a target guidance line is determined in this plane, and further preferably guidance data are determined, whereby the moving object can be guided along this plane. The lateral inclination can be defined, for example, by a tilt value set by the user or by a connection line of the base station to the other, stationarily installed measurement beam receiver.

[0085] In particular, a method is proposed for determining the height and attitude of a vehicle by means of a measuring device for optical or quasi-optical position determination, the measuring device having at least one active target fixedly associated with the vehicle and at least one base station, where the active target is arranged in the detection range of the base station, at least one other stationary active target is provided, and across the connection line between the base station and the stationary active target, a segment of a virtual guidance wire as well as a virtual laser surface with a predefined lateral inclination is provided, where the vehicle is guided at its working height using the orientation angle of the base station obtained by the active target, similar to a conventional guidance wire.

[0086] In such a method, it is advantageously possible to configure a chain of segments of a virtual connection line, in which base stations emitting radiation, preferably optical radiation, and stationarily installed active remote stations, i.e. preferably measurement beam receivers, alternate along this chain, and this chain of segments forms a virtual guided wire, where each base station can be assigned two virtual laser planes, which are determined by calculation from the station's direction angle by the respective adjacent stationarily installed active remote stations or targets.

[0087] Here, the active remote station does not have to simultaneously function as a base station, but can be a purely beam receiving active remote station. This advantageous configuration significantly reduces the constructional effort for obtaining a given length of virtual connection line when the base station coverage area, i.e. the radiation capacity, is the same. It should already be disclosed as an advantageous variant that communication between various interpolation points can take place in such a system, possibly in order to inform other stations of their own, possibly critical operating state and / or to inquire about the operating state of other stations.

[0088] It should also be mentioned that in the case of an advantageous use of the described method for guiding a moving object, it is particularly advantageous to smooth the guidance data determinable for the various segments and / or to interpolate at least at the transitions of the segments, preferably with reference to additional information in each case, particularly preferably with reference to the intersection of the planned course of the taxiway with the direction angle and / or the odometer value, whereby control parameters for the automatic movement of the moving object are preferably determined as guidance data.

[0089] It should be pointed out that the above-described method for guiding a moving object can also be realized using a prior art base station, for example as shown in Figure 1. This in itself is considered novel, as is the use with a wobbling area beam.

[0090] Furthermore, the base stations according to the invention or known from the prior art, used in the above-mentioned method, may be configured as measurement beam transceivers in the same way as in EP 2 998 699 A1, which is likewise considered to be novel.

[0091] The invention will now be described, purely by way of example, with reference to the drawings, in which: [Brief description of the drawings]

[0092] [Figure 1] FIG. 1 shows four different exemplary measurement devices of the prior art, as described in the introduction. [Diagram 2] FIG. 1 shows an overview of an advantageous measuring device. [Diagram 3] FIG. 2 shows an advantageous measurement device with an active target, the received signature of which is shown for two different heights. [Figure 4] FIG. 1 shows a measurement setup with an active remote station having two vertically overlapping receivers with known spacing b to remove ambiguity and determine 3D coordinates relative to the base station. [Diagram 5] FIG. 1 shows a measurement device with an active target to which a GNSS antenna is assigned for disambiguation purposes, where the active target allows the 3D coordinates of the GNSS antenna to be refined. [Figure 6] FIG. 2 shows a measurement device with two base stations having a base spacing b for removing ambiguity and determining the 3D coordinates of an active target. [Figure 7]FIG. 1 illustrates six alternative arrangements of optical components at a base station. [Figure 8] FIG. 2 is a cross-sectional view of the optomechanics of a particularly advantageous configuration of the base station. [Figure 9] FIG. 2 is a block diagram of a control circuit of a particularly advantageous configuration of a base station; [Figure 10] FIG. 2 is a block diagram of a particularly advantageous configuration of an active target. [Figure 11] 13 is an example and illustration of a possible configuration of an angle-encoded data signal after reception at an active target at a base station. [Figure 12] FIG. 2 shows the mounting of a laser sensor on a construction machine in a method for guiding the construction machine in road construction (prior art, already described). [Figure 13] FIG. 2 is a top view of the road progression in the prior art method described in the introduction. [Figure 14] FIG. 1 shows the installation of active targets in the proposed method for determining vehicle height and attitude. [Figure 15] FIG. 13 illustrates the interpolation at the transitions between the virtual laser plane and the interpolation points when implementing the method of the present invention using virtual guide lines or virtual string lines. [Figure 16] FIG. 16 is a top view of the road course and road finisher when implementing the method also described in FIG. 15 using a virtual string line. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0093] 2 shows a measuring device, generally designated by the reference number 1, with a base station 2 which emits measuring radiation in a surface. Here, the base station 2 is configured for a wobbling movement of an area beam 4, by which the attitude of the normal 6 of the area beam 4 is changed in a known manner, such that a succession of orientations of the area beam normal 6 is performed in a known manner, see phase angle ψ (psi). Furthermore, the measuring device 1 has an active remote station 3, i.e. an active target 3, which receives the measuring beam emitted from the base station 2.

[0094] In the embodiment shown, the base station 2 is arranged on a sufficiently stable tripod stand 36 and emits visible light as measurement radiation. In the embodiment shown, the base station 2 is installed such that the axis 8 is oriented vertically. As will be further explained with reference to FIG. 7, in the base station 2, the optical elements deflecting the beam rotate about this axis 8. Due to the wobbling movement of the embodiment of FIG. 2, the normal 6 to the surface beam 4 is now tilted by an angle α (alpha) with respect to the axis 8, and the end point of the normal unit vector 6 intersecting the axis 8 rotates on a circle around the axis 8. The phase angle ψ (psi) indicates the phase of this circular rotation in which this normal vector lies.

[0095] The active target 3 may be fixed, for example detachably or non-detachably, to the object to be surveyed (not shown) or may be held on this object or may be fixedly or movably installed for position measurements on this object. It is understood that the wobbling surface beam sweeps the active remote station 3, which is located at a suitable height, twice with each wobble cycle. The active target 3 has a photosensitive element to generate a characteristic signal each time the measurement radiation is received, which is caused by the sweep. From the signature of this characteristic signal, symbolized by the curve at the receiver 42 in FIG. 2, the normal orientation at each time the measurement radiation is received can be deduced, as will be further described hereinafter.

[0096] To generate a wobbling surface beam, an optoelectronic beam-transmitting element 12 is arranged in the base station 2 (see Fig. 7a-7f), where the optoelectronic beam-transmitting element 12 is followed by optical elements for shaping and inverting the beam of the optoelectronic beam-transmitting element 12. There are a number of optical arrangements that can realize the desired wobbling movement of the surface beam 4. Some of these optical arrangements are described with reference to Fig. 7a-7f.

[0097] In Fig. 7a, a particularly advantageous variant of the arrangement of the optical components of the base station 2 is shown. Here, the optoelectronic beam transmitting element 12 is a laser diode 12 which emits a diverging beam bundle. This is converted into a substantially parallel, collimated beam by a collimator 10, which in the illustrated embodiment is configured as a biconvex lens in the best mode. This collimated beam then enters a rotating beam deflection element 7, which in the illustrated embodiment of Fig. 7a is a rotating square prism. The square prism here rotates about a rotation axis 8, which is again parallel to the propagation of the collimated beam bundle 11.

[0098] In the embodiment shown in Fig. 2, the axis of rotation 8 is vertical and the wobbling surface beam 4 has a normal vector 6 which is inclined by a deflection angle α with respect to the vertical axis of rotation 8. To drive the rotation of the square prism, an electric motor 18, shown only diagrammatically in Fig. 7a, is provided which generates the rotary motion.

[0099] Thus, the collimated beam bundle, which is correspondingly deflected periodically during the rotation of the square prism in different directions, but always inclined relative to the vertical line 8, is incident on a 90° conical mirror 5 in the embodiment of FIG. 2. This conical mirror 5 converts the deflected and collimated beam bundle into a surface beam 4, which is further inclined there. The inclination of the surface beam 4 is now located behind the conical mirror 5 in such a way that the normal 6 to the surface beam 4 stands inclined at an angle α to the vertical axis of rotation 8. As can be seen from FIG. 2, the normal 6 periodically cycles around the vertical line 8 corresponding to the rotation of the square prism, so that the surface beam normal 6 repeatedly assumes the same orientation during the rotation of the square prism, where the current orientation of the surface beam normal 6 is always known, as long as it is known how the square prism is currently oriented by the rotation of the square prism caused by the rotary motor 18 around the vertical axis of rotation 8. Further below, an advantageous approach is presented how the current orientation of the square prism can be determined and transmitted to the active target 3 by rotation of the square prism caused by the rotation motor 18.

[0100] The conical mirror 5 expands the deflected and collimated beam bundle to form a surface beam, and thus in this respect a beam expansion component is realised.

[0101] It should be noted that in the illustrated embodiment, the surface beam has a finite thickness, which is furthermore different in different directions. This can be seen in Fig. 7a and Fig. 7b. This effect of the varying thickness can be best understood if it is assumed that the tip of the conical mirror 5 is located exactly on the vertical axis 8, and furthermore that the conical mirror symmetry axis passing through the tip of the conical mirror 5 is located exactly on the vertical axis 8. It is further assumed that the collimator collimates the radiation from the optoelectronic beam transmitting element 12 into an exactly circular and homogenous bundle of parallel individual beams. (It should be clearly pointed out that these assumptions of exact orientation are made only in order to be able to better explain the effect of different thicknesses, the realization of these assumptions is not necessary for practical implementation, and the invention or this particular embodiment should in no way be limited to this assumed accuracy. The reader should therefore be pointed out that neither the exact location of the conical mirror tip on the vertical axis, nor the exact coaxial orientation of the conical mirror symmetry axis passing through the tip of the conical mirror 5 with the vertical axis, nor the exactly divergence-free collimated and exactly circular beam bundle, as described above, are actually necessary, and the respective inaccuracies and deviations can easily be tolerated in some cases, or can be corrected if a higher accuracy is desired. However, it should nevertheless be mentioned that without great effort a high constructional accuracy can be obtained in the direction of this simplifying assumption made for a better explanation.)

[0102] With this simplified assumption of the conical mirror orientation, it is possible to understand particularly well why the beam thickness varies in different directions, by observing the beams located in the center or at the outer edge of the collimated beam bundle for two directions, i.e. the beam in the direction with the maximum upward-facing beam tilt away from the conical mirror 5, or the corresponding beam in the opposite direction with the maximum downward-facing beam tilt.

[0103] The central beam of the collimated beam bundle enters the conical mirror 5 very close to the tip of the cone. These respectively define the lower limit of the surface beam, i.e. in the direction in which the surface beam rises and in the opposite direction in which the surface beam falls. However, since the collimated beam bundle is inclined with respect to the vertical 8 and thus to the axis of the conical mirror, the outer beams of the beam bundle are directed towards the vertical axis 8 on one side, whereas on the opposite side they move away from the vertical axis 8. Correspondingly, the outer beams of the collimated beam bundle enter the conical mirror 5 at different heights. This can be clearly seen in FIG. 7a. Due to this different height of incidence, after deflection by the conical mirror 5, the thickness of the surface beam is different in different directions. FIG. 7b shows that the thickness of the surface beam changes in direction corresponding to the change in the beam inclination. The same arrangement as in FIG. 7a is now shown in FIG. 7b, but in FIG. 7b the orientation of the beam path is additionally shown in dashed lines for the orientation of the square prism which has been further rotated by 180°.

[0104] Note that different thicknesses affect when it is determined that the optical receiver is swept by the wobbling areal beam.

[0105] However, this effect can be calculated exactly and compensated for by calculation. Moreover, the tip of the conical mirror can almost touch the surface of the square prism without beam shadowing of the surface beam if the inclination angle of the surface beam corresponds exactly to the prism angle. This is the case when the material of the square prism has a refractive index of 2.0. That is, the corresponding imaging error resulting in a varying thickness is not critical in practice.

[0106] Fig. 7c shows that the offset problem that changes the thickness of the planar beam can be substantially optically compensated for and how it can be compensated for. The optical element used in this embodiment for beam deflection includes, in addition to the square prism 7 that is also used, a plane-parallel plate that is arranged in the beam path between the collimator 10 and the square prism 7 and is inclined with respect to the axis of the collimated beam. The inclined plane-parallel plate is coupled to the square prism 7 in such a way that it cannot rotate relative to the square prism 7, so that the inclined plane-parallel plate rotates with the rotation of the square prism 7 in Fig. 7c. In this embodiment, the beam deflection component includes, in addition to the square prism, an inclined parallel plate.

[0107] Fig. 7d shows a further embodiment, which differs from the embodiment of Fig. 7a in that in Fig. 7d the parallel, collimated beam is transformed into an annular beam, i.e. with an intensity across the cross section that is low in the center but has an annular region of higher intensity away from the center. This annular beam profile is obtained by adding two axicons to the collimator. The annular beam profile has an advantage with respect to the divergence of the planar beam in the vertical line. Thus, a beam of a given power can be detected even at a greater distance from the base station 2. The reach of the base station 2 and the measurement accuracy obtained therewith can be improved with such an annular beam profile.

[0108] In the embodiment of FIG. 7e, the conical mirror 5 of FIG. 7a is replaced by a 90° plano-concave axicon. The illustrated plano-concave axicon is formed in the embodiment as a vertical cylinder. It has a flat end face facing the optical transmitter 12 and a conical recess at the end face facing away from the optical transmitter 12. The surfaces of this plano-concave axicon are optically polished. The beam bundle entering the flat end face of the plano-concave axicon from the side of the optical transmitter 12 is redirected by total internal reflection in the conical recess and emerges from the outer surface. The use of such a plano-concave axicon has advantages in the mechanical construction of the base station 2, because unlike a conical mirror, the axicon can be easily held, so that glass tubes, glass housings or completely opaque frame structures do not block part of the beam or weaken it during its passage.

[0109] Due to its cylindrical shape, the illustrated axicon can be held with little effort, especially below the beam exit area, together with the rotating beam deflection optical element, coaxially to the axis of rotation, for example in a suitable tube. However, it should be pointed out that the tip of the conical recess of the axicon cannot be located close to the exit surface of the beam-deflecting angular prism, as is the case with the tip of the conical mirror 5 in FIG. 7a. For this reason, advantageously, when a plano-concave axicon is used instead of the conical mirror 5, two interacting angular prisms are used instead of the individual rotating angular prisms in FIG. 7a, which deflect the beam with different strengths, since the above-mentioned deflection by the rotating angular prism, which results in different surface beam thicknesses, has a stronger effect. These angular prisms together ensure a central or nearly central incidence of the deflected beam on the conical surface of the plano-concave axicon.

[0110] An embodiment is shown in FIG. 7f, which does not provide particularly high measurement accuracy, but allows particularly small construction sizes and extremely low costs. In this example, the beam deflection means are identical to the means for expanding the beam into a surface beam. In other words, here the beam deflection component 7 is identical to the surface beam expansion component 5. A conical mirror 5 is used, whose axis of symmetry is tilted by an angle α / 2 with respect to the axis of rotation 8 (vertical in FIG. 2). This is an exceptionally easy solution, but it entails problems in the stability of the deflection, since the dynamic errors of the mechanical support of the axis of rotation in the normal configuration and the normal tilt angle of the normal of the wobbling surface have an influence that is more than ten times stronger than in the case of the arrangement of FIG. 7a. This variant of FIG. 7f is therefore only advantageous when extremely high measurement accuracy is not important, such as, for example, in the case of a miniaturized integration of a base station into a smartphone or the like, but instead extremely small construction sizes and extremely low costs are important.

[0111] The depicted optical components allow an advantageous optomechanical construction of the base station 2. This is illustrated by way of example in Fig. 8 for a mechanical structure of an embodiment substantially corresponding to the configuration of Fig. 7a.

[0112] FIG. 8 now shows a cross-sectional view of the optomechanics of this particularly advantageous variant of the base station 2.

[0113] The optoelectronic beam transmitting element 12 here is a laser diode emitting a diverging beam bundle. The diverging beam bundle is transformed into a parallel (infinite) converging beam by a collimator lens 10. As can be seen, the laser diode 12 and the collimator lens 10 are fixedly attached to each other. They are inside a hollow shaft 8 which is rotatable about them, and which is fixedly connected to an angular prism 7. More precisely, the angular prism is fitted into the hollow shaft.

[0114] The hollow shaft is rotatably supported by a bearing unit 9 pretensioned without play and driven by a rotary drive realized as a brushless motor 18, and thus rotated together with the square prism. For this purpose, the motor 18 has a stator 19 and a magnet rotor 20 which is connected to the hollow shaft in such a way that it cannot rotate relative to it. At the same time, an encoder disk 21 is attached to this rotor, which is scanned by two encoder read heads 22. From the signals obtained during scanning of the encoder disk 21 with the encoder read heads 22, the rotation angle of the magnet rotor can be determined in real time, and at the same time, the centering error of the encoder disk as well as the bearing runout are compensated for.

[0115] The beam bundle deflected and collimated by the square prism enters the conical mirror 5 which, as described above, expands the beam bundle into an inclined surface beam and produces the desired known wobble of the surface beam as the square prism rotates, so that from the signal obtained by scanning the encoder disk 21 by the encoder read head 22 not only the rotation angle of the magnet rotor can be determined in real time, but at the same time the rotational orientation of the square prism and thus the phase angle in the motion cycle of the surface beam normal 6 is known.

[0116] To protect the optical components, the base station has a transparent cover 38 on the beam exit side, which is formed as a glass housing or preferably as a glass tube with closed ends, through which the fluctuating surface beam is emitted into the measuring space to be surveyed.

[0117] In particular, for controlling the beam emission by the laser diode 12 and for controlling the rotation drive by the motor 18, a control unit 23 is provided, which detects the electrical rotation angle signal of the encoder read head 22 and generates therefrom a data signal 14 (angle-encoded with the angle calibration data) which is supplied to a driver circuit 13 of the laser diode 12 for modulation of the radiation power.

[0118] Figure 9 shows a block diagram of this control unit. The control unit comprises a current supply 24 and an interface for calibration and debugging. The control unit further comprises suitable encoder and motor electronics 25, via which it is connected to the motor 18 and the encoder read head 22, so that a central computing unit 33 can determine the motor speed.

[0119] The control unit advantageously further manages not only the user interface 27 but also radio-frequency reading devices 26 for position tags or transponders 37, for example configured with RFID or NFC technology. These can be arranged on the stand 36 or attached to the connection points between the stand and the base station (for example tripod, tripod or leveling plate) and correspond to a previously determined absolute position. The absolute position can for example be measured by stationary GNSS before the survey. Such a reference of the absolute, for example stationary GNSS or tachymeter calibrated position of the stand of the base station makes it possible to realize extensive virtual guide lines, if virtual guide lines are desired, with only a small number of base stations that move in accordance with the construction progress. This leads to significant cost savings compared to the prior art and at the same time to improved handling by the user.

[0120] It should be mentioned that the approach of calibrating the installation points of the base stations to a static absolute position, in particular by means of a stationary GNSS or tachometer, and storing this data in a transponder at the base station stand or installation point, is considered advantageous compared to the prior art and is considered protectable as such. This allows, for example, a virtual guide line to be built with the base stations moving from one static calibrated position to the next static calibrated position depending on the progress of the works. The filing of a separate application for this purpose is expressly reserved. It should be emphasized that such a method is applicable with conventional base stations that do not emit a wobbling surface beam in a defined and understood manner. The method is likewise applicable in particular to tachometers known from the prior art as well as to dual-inclined lasers, etc.

[0121] If the control unit 23 is configured to detect the absolute position, for example the absolute position of a previously measured position tag, the control unit 23 is advantageously configured to modulate the beams receivable by the active targets, i.e. to transmit the absolute position of the respective base station 2 regularly, for example every few seconds. In this respect, the absolute position is auxiliary information that is placed on the radiation emitted by the base station for modulation. It should be mentioned that it is possible, if necessary, to provide the base station 2 with its own GNSS receiver, which may make a prior measurement of the target installation position relative to the base station 2 unnecessary.

[0122] The base station 2 further comprises a tilt compensator 28 which outputs a tilt indication signal to the control unit 23, which signal can likewise be used for the repetition modulation of the emitted radiation.

[0123] In the illustrated and advantageous embodiment, the control unit 23 has an interpolator 31, by means of which the data words encoding the angular position are output in a position that is precisely calibrated for the encoder. By storing corresponding correction data in a calibration memory 32, less linear encoder disks can now be precisely calibrated, so that less linear but still highly accurate angular data are generated. The correction data required for this can be easily determined and stored for each encoder disk during production. It should be pointed out that the calibration memory can in particular be configured as a non-volatile memory.

[0124] The interpolator 31 converts the angle data, which are preferably associated with integer indices in fixed angle steps, and preferably also other auxiliary information, into a data format suitable for modulating radiation, taking into account, if necessary, redundancy and the presence of checksums.

[0125] In an advantageous variant of the transmission of angle information at a fixed angle position, the angle information is transmitted at fixed time intervals. The angle thus given at a fixed time point can be determined in the base station by interpolation of the angle encoder data and then transmitted as angle information at the fixed time point. This has the advantage that the start of the data word can be detected very well at the active remote station, even without an emphasized start pulse. This is likewise advantageous, since the available laser power can be better utilized and thus the reach of the base station can be increased.

[0126] An example of a data format suitable for optical data transmission is the MPPM format or modified MPPM signal with 8 symbols, i.e. light pulses, in 128 positions. This allows the coding of 40 bits of information per data word. The use of a data protocol other than the PPM data transmission protocol, i.e. the MPPM protocol, for imposing for modulation on the measuring radiation emitted by the base station is considered as novel in itself, which also applies to base stations, rotating lasers, etc. that are otherwise constructed according to the prior art.

[0127] Before describing the data protocol used in more detail, reference will be made in detail to the structure of the active remote station 3. This makes sense in that the data protocol used advantageously is designed to achieve particularly high accuracy together with a cheap and robust receiver.

[0128] Fig. 10 shows a block diagram of an active remote station, i.e. active target 3, belonging to the abovementioned base station 2. The active target 3, in particular for use with construction machines, has a receiving collimator 40, by which the light is focused and input into a light guide 41, which guides the radiation incident from the base station 2 to a photosensitive optoelectronic element, such as a photodiode. The light guide 41 may in particular be a plastic optical fiber (POF), which is several meters long and allows a spatial separation between the area of ​​incidence of the radiation on the active target 3 and the optoelectronic and electronic components used for the detection and evaluation of the radiation reception signature.

[0129] On sweeping of the surface beam over the receiving collimator 40, the optical radiation is focused into and input into the light guide 41. The receiver 42, which can be realised as an independent component and, for example in construction machine applications, can be securely mounted inside the machine, is thereby connected with the outside world only via the light guide 41, which can be several metres long.

[0130] In such an arrangement, the original measuring point is the receiving collimator 40, which may be mounted on the outside of the construction machine, which offers considerable advantages, among other things, with regard to the overall sensitivity to vibrations and watertightness of the arrangement. The photosensitive optoelectronic elements may be assigned an optical filter for suppressing optical interference radiation, typically using a bandpass filter 43 with a wavelength transmission range only a few nanometers wide, centered on the emission wavelength of the base station 2. This filter can be arranged, for example, in front of the entrance lens of the receiving collimator 40, in the receiving collimator 40, between the receiving collimator 40 and the light guide, or between the light guide and the photosensitive electronic elements. Advantageously, however, the optical filter is provided as close as possible to the optoelectronic elements, since in such a case it is typically possible to use filters that only have small constructional dimensions, which offers advantages in terms of price and weight.

[0131] Here, advantageously, the optically filtered light is incident as an optically received signal 44 on a photosensitive optoelectronic receiving element 45. Particularly advantageously, for this purpose, a conventional avalanche photodiode (APD) or a linearly operated silicon photomultiplier, the bias of which is controlled by a calculation unit 53, is used.

[0132] The photosensitive optoelectronic receiving element outputs an electrical signal that is fed to a signal conditioning circuit 48, where in this example a transimpedance amplifier (TIA) with an analog optimized filter is used. The analog output signal obtained after signal conditioning is likewise converted by a high-speed ADC 49 into data of a digital data stream 50. This data stream is fed to a digital pre-processing and compression circuit 51, which further processes the received data stream digitally. This is done by removing from the data stream noise and useless signals or interference signals such as interference events due to scattered light, so that the subsequent computing unit is provided with only the data of the data stream that is actually required for further processing. That is to say, such digital data stream processing compresses the data stream.

[0133] Advantageously, such data compression can be carried out by particularly inexpensive data processing units, in particular because the same data processing steps only have to be performed repeatedly. Specially configurable units such as FPGAs are suitable for such steps. The use of data compression is generally advantageous, since they have low power consumption and allow a computing unit with a relatively low computing power to be used for the further processing of the compressed data stream. In this regard, it should be mentioned in particular that by using an FPGA-based data compressor, the otherwise required power consumption can be reduced by a factor of about ten, which is particularly advantageous when the active target 3 is to be constructed as a fully integrated, battery-powered handheld receiver, advantageously without the above-mentioned light guide. However, it should be mentioned that the compressor 51 can also be omitted, in particular when the power consumption plays at most a subordinate role and at the same time a computing unit with a sufficiently high computing power is available.

[0134] It should be mentioned that the receiver, i.e. the active target 3, is advantageously further equipped with a communication interface 54, in particular for a wireless connection via WLAN, by means of which it is possible to communicate with other active targets 3 if necessary and to transfer the calculated position information.

[0135] Using the above-mentioned measuring device 1, which has a base station 2 and an active remote station 3 generating a wobbling surface beam in a known manner, it is possible to determine at what angle to the horizon the supposed connection line rises between the active remote station on the one hand and the two wobble centers of the surface beam, located in the base station on the other hand. This inclination angle is referred to below as the vertical direction angle. In FIG. 2, it is indicated by the Greek letter λ (lambda).

[0136] In FIG. 2, the position of the active remote station 3 relative to the base station 2 is given in spherical coordinates, the center point of which is the center of the planar beam wobble movement, and therefore in addition to the vertical direction angle, the horizontal direction angle and the distance to the base station 2 are necessary. It is understood that for the vertical direction angle and the horizontal direction angle, the direction needs to be defined at 0°. In the case of the vertical direction angle, a precisely horizontal direction with zero tilt is particularly good. In contrast, in the case of the horizontal direction angle, the direction itself may be defined arbitrarily. In practice, a direction such as north would be particularly good, but here it may be considered sufficient if the horizontal direction angle is related to a direction defined as 0°, to which the phase angle in the movement cycle of the planar beam normal is associated. In this regard, it has already been mentioned above that the phase angle in the movement cycle of the planar beam normal corresponds to the rotation angle of the rotary motor driving the angular prism, and that this rotation angle can be determined by an angle encoder. Without limiting generality, the 0 direction can be used to define the horizontal direction 0°.

[0137] Based on the wobble motion generated in a planned manner by the use of the above-mentioned optical system in the base station 2, the surface beam normal 6 rotates in a circle as shown in FIG. 2. Here, each active remote station 3 is swept twice per circular rotation, i.e. per wobble cycle (as long as the radiation incidence surface of the active remote station 3 is in any case between the maximum and minimum heights that the surface beam can assume). The sweeping occurs at a specific phase angle. If the two phase angles ψ1 and ψ2 at which the active remote station is swept are known, the horizontal direction angle can be easily calculated initially from their average value, i.e. corresponds to (ψ1+ψ2) / 2.

[0138] To determine the vertical direction angle λ (lambda), i.e. the rise or fall angle of the envisaged connection line between the active remote station on the one hand and the wobble centre of the surface beam, located in the base station 2 on the other hand, it is further necessary to use the angle at which the normal 6 to the surface beam 4 is inclined with respect to the vertical axis 8. This angle is shown as angle α (alpha) in FIG.

[0139] At given phase angles ψ1 and ψ2 at which the active remote station 3 is swept by the wobbling surface beam 4, these variables define the vertical direction angle λ (lambda) as:

number

[0140] In contrast, in FIG. 3, it is symbolically shown how the interval between the sweep events is affected when an active target changes its height at a given distance from the base station 2. The change in height is accompanied by a change in the time interval between the sweep events, since the area beam 4 requires different lengths of time, depending on the height of the target, after the first sweep before it further wobbles into the orientation in which the second sweep is observed. The different lengths of time duration obviously correspond to different distances of rotation of the area beam normal 6, which is simultaneously executing its own motion cycle. However, it is also clear from FIG. 3 that the central time point between two sweeps is not related to the height of the target. It should be emphasized that this characteristic corresponds completely to and is expressed in the above formula.

[0141] However, in a simple device such as that of FIG. 2, initially only the signature of the repeated sweep of the active remote station 3 by the surface beam 4 is detected, but it should be noted that here it is not clear whether the observed signature occurs at an elevation above the horizon or at an elevation below the horizon (in the above equation this is affected by the sign ambiguity).

[0142] Although it is possible to avoid such ambiguity by restricting the measurement space to half the space, it is also possible to resolve the ambiguity by relatively simple measures without such a significant measurement space restriction. In this regard, the approach described below with reference to Figures 4 to 6 should be pointed out.

[0143] In FIG. 4, it is proposed to resolve the ambiguity by two active remote stations 3a and 3b arranged one on top of the other, so that the height of each active remote station can be determined unambiguously from the four detected sweeps. It should be emphasized that in some cases it is not necessary to use two identical, completely separate active remote stations, but it is also possible to provide individual remote stations with two optical receivers or optical collimators arranged one on top of the other. Thus, a particularly suitable active remote station 3 has more than one individual optical receiver. Particularly advantageously for this device, if the vertical spacing b of the optical receivers arranged one on top of the other is known, then the spacing between the active remote station 3 and the base station 2 can also be determined. Thus, taking the base spacing b again, if the height of the beam wobble center is known, it is possible to calculate the height coordinate z of the active remote station 3 and the spacing r of the active remote station 3 to the base station 2.

[0144] Thus, the 3D position of the active target 3 in the polar coordinate system of the base station can be determined by a receiver arrangement as shown in Fig. 4. It should be pointed out that if additional receivers are provided, the accuracy can be increased by interpolation and / or the orientation of the active remote station 3 in space can also be detected if further additional receivers are appropriately positioned on the active remote station 3.

[0145] Moreover, it is advantageously permitted, without any disturbance of the measurement accuracy, that the connection line between the two receivers 3b, 3b does not run exactly perpendicular to the vertical line, but runs at an incline. Thus, in the advantageous embodiment of the active remote station 3 described with reference to Fig. 4, the active remote station 3 is equipped with an inclinometer, whose measurements can be used to compensate for the current inclination.

[0146] As an alternative and / or additional possibility, Fig. 5 shows that the ambiguity can be resolved by combining the active target 3 with position or attitude information of the GNSS antenna. At the same time, if an absolute position determined by GNSS is required, the accuracy of the GNSS measurement can be increased when referring to the calibrated absolute position of the base station 2 and the position determined here relatively by the active remote station 3. The accuracy of the GNSS position can be significantly improved, especially with regard to the height measurement. This arrangement is particularly advantageous when a high accuracy of the absolute position is absolutely required.

[0147] Fig. 6 shows a further arrangement capable of automatically resolving ambiguities, where two base stations 2a and 2b are installed with a known base distance b and are mutually calibrated with respect to their horizontal axes. In case of an active target 3 which is located in the measurement space of both base stations, i.e. can receive radiation from both stations for measurement purposes, the 3D position of the active target 3 can be determined by 3D triangulation.

[0148] Here, the following implementation is particularly advantageous: at each of the two base stations 2 used, a passive target 34a and 34b is mounted, preferably aligned with the rotation axis of the respective other station, the base stations themselves being, as described above, also configured for receiving radiation, in particular so that in addition to the horizontal and vertical angles, the lateral distance between the two base stations can also be measured by determining the pulse propagation time from the first base station to the reflecting passive target of the second base station and back.

[0149] Such an arrangement has the advantage that the stations can be automatically calibrated during installation and that the acquired information about each adjacent station can be transmitted together with auxiliary information via modulation of radiation to the active remote station 3 without the need to initiate a calibration process or for the results of the calibration process to be queried via the wireless interface, whereby the installation process is as simple as in the case of a total station.

[0150] As far as the height determination is concerned, in all variants it would basically be sufficient to determine the sweep time and then assume the parallel rotation speed of the square prism. However, this not only limits the accuracy as soon as parallel variations occur, but also makes a complete determination of all coordinates of the active remote station 3 impossible. Therefore, in the above description it is assumed that the actual rotation angle of the square prism rotation or the phase angle in the motion cycle of the surface beam normal itself is known.

[0151] Furthermore, it has already been pointed out that the corresponding information can be determined by means of an angle decoder, and the corresponding angle data of the radiation from the base station 2 can be loaded for modulation.

[0152] With reference to FIG. 11, details of a data protocol particularly suited to the modulation of an optoelectronic beam transmitting element, here a laser diode 12, will now be described.

[0153] It should first be recalled for this purpose that the wobbling surface beam 4, as shown above, can vary in different directions, but in each case has a regularly finite thickness. Thus, when the receiver is swept, a finite time passes between the first beam entering the receiver and the last beam leaving it. On the one hand, this time of beam reception is sufficient to receive the encoded information. On the other hand, the wobbling surface beam continues to move during this time, i.e. during the sweep, the phase angle of the surface beam normal 6 changes.

[0154] On the one hand, this can be exploited for the reception of a series of time-coded data and, on the other hand, it can be taken into account in order to increase the accuracy of the measurements.

[0155] Advantageously, for this purpose, in particular information about the current rotational angle orientation of the rotating square prism and thus about each current phase in the motion cycle of the surface beam normal is transmitted from the base station 2 to the or each active remote station 3. A suitable protocol for data that can be imposed for modulation on the radiation emitted from the base is explained with reference to FIG.

[0156] Furthermore, Figs. 11a to 11c show the time course of the radiation power of radiation emitted by a base station, characterized by the information carried by the modulation.

[0157] In the illustrated and advantageous implementation, data words 15 are then used, each having a width of 40 bits, each consisting of a start symbol for synchronization and eight subsequent data symbols, each easily identifiable by the receiver, each symbol being realized by a generally needle-like pulse.

[0158] The desired information is coded by the time position of the eight needle-shaped pulses which correspond to the data symbols and follow each start symbol before a new start symbol is generated. In the illustrated embodiment, each of the eight needle-shaped pulses is on one of the 128 codable time positions. As Fig. 11c shows, this results in a time change of the modulation pattern, corresponding to the data to be transmitted. The start symbols are particularly easily identifiable, since they are different from the data symbols. There are various ways of doing this. In Fig. 11a, a stronger pulse is used for the start symbol than the pulse of the data symbol. Such coding is called bilevel coding. In Fig. 11b, a double pulse is used instead, which is built up from two needle-shaped pulses which are very close to each other in time. The time interval between the pulse peaks of the double pulses which are very close to each other is so short that it does not appear in the rest of the data word. That is to say, the time interval of the double peak is shorter than the shortest time interval of the 128 codable time positions.

[0159] It should be noted that the start symbol is not only used to identify a new data word. Rather, from the time sequence of the start symbol pulses, the synchronization can also be deduced, i.e. the active remote station 3 determines how much time the base station 2 needs to transmit a complete data word, and from this it can deduce how long the time intervals between the 128 protocol-coded time positions last. Here, this synchronization can be carried out, presuming appropriate computing power in the active remote station 3, for example, under autocorrelation to the time intervals between the start symbol pulses.

[0160] Furthermore, in order to better utilize the radiation capacity of the beam transmitting elements and thus to increase the range obtained, it may be advantageous if the start symbol is not bi-level coded, i.e. is not transmitted with a distinguishable amplitude compared to the data pulses, and even if no double pulse is transmitted at the beginning of the data word. Rather, a specific start pulse can be omitted completely. In such cases, for example, brute force decoding using a checksum or soft decoding or autocorrelation using a fixed time interval between the data words can be used for synchronization.

[0161] In FIG. 11c, a sequence of a number of different angle-encoded data words 15 is shown, each of which corresponds to a rotation angle position ψ detected at the time of the start pulse. n-1 ~ψ n+2 Encode the following.

[0162] The data protocol allows a sufficiently fast and interference-free data transmission by modulation of the emitted radiation. In a practical embodiment, for example, it was possible to transmit a data word 15 as described above within 2.5 μs. This allows the current rotation angle information or auxiliary information to be transmitted sufficiently frequently.

[0163] It should be pointed out that the described transmission method makes latency problems in transmission between a base station and an active remote station practically insignificant. Although there may be a time delay between detecting a certain rotation angle position by the angle decoder in the base station 2 and placing the corresponding information on the emitted radiation for modulation, this latency occurs within the base station and, moreover, is to a good approximation quite constant in relation to time, i.e. ignoring, for example, temperature effects (which can, however, be reduced by temperature regulation). In this respect, this transmission differs from current communication of angle information via other communication paths, such as WiFi, since here the latency can vary greatly. The described data transmission is therefore particularly advantageous, which also applies to base stations according to the prior art with a non-wobbling surface beam.

[0164] In the above-mentioned implementation, so-called Pulse Position Modulation (PPM) is applied. It should be disclosed that in addition to such PPM modulation, other modulation methods as known per se from the prior art are applicable. In particular, the usefulness of Manchester coding as well as PSK, QPSK, QAM modulation methods is expressly disclosed, without being limited thereto.

[0165] The measurement accuracy is increased by the transmission of the angular encoder data by the described modulation. As mentioned above, it takes a certain time for the receiver at the active remote station 3 to be completely swept by the wobbling surface beam, since the surface beam has a finite thickness and the receiver has a finite extension. During this duration, the orientation of the wobbling surface beam also changes. It is therefore proposed to increase the measurement accuracy by determining the temporal center of gravity of the sweep interval and by interpolating the angular information obtained during the sweep interval by the modulated received radiation relative to this temporal center of gravity.

[0166] It should be noted here that the power received at the receiver of the active remote station 3 varies during the sweep. This is already easily explained by the fact that the entire face of the receiver is only incident on the surface beam during part of the sweep interval, while parts of the receiver are not incident on the surface beam at the beginning and end of the sweep. This effect results in the existence of an envelope curve 47 which varies the received power, as shown by way of example in FIG. 11 d.

[0167] For the interpolation of the angular information, i.e. for the accurate determination of the phase angle in the motion cycle of the surface beam normal, it is first necessary to determine the time center of gravity of this envelope curve, with respect to which the associated angle is then determined by interpolation.

[0168] However, the envelope curve itself is not readily available. However, it is not absolutely necessary, since it is sufficient to consider the height of the pulse peaks modified by this curve. That is, at this point, the analog shape 46 of the data stream modified by the envelope curve is taken up again. This can be done by defining a reasonable and low received power threshold, above or below which the start time t start and stopping time t end This can be particularly easily achieved by determining, see FIG.

[0169] Therefore, a reasonable bound t start and end If one wishes to determine the temporal center of gravity between

number

[0170] The value of the temporal center of gravity obtained in this way is only slightly related to the data content of the data word, since this is coded via the time position of the needle pulses, but this nevertheless still makes it possible to determine the temporal center of gravity very well.

[0171] In Fig. 11d, the temporal center of gravity is t c This time center of gravity is the time instant t n and n+1 These are located between and at time t c The two rotation angles or phase angles ψ are calculated and transmitted just before or just after n Or ψ n+1 Encode the following.

[0172] Using these symbols, the interpolated angle that best corresponds to the temporal centroid of the sweep of the planar beam across the optical receiver can be determined as follows:

number

[0173] This rotation angle can then be used to calculate the direction angle according to the formula above.

[0174] This technique can be used to interpolate between the angle steps encoded by the transmitted data words to much better than 1 / 10 of the angle step interval. Typically, an accuracy of better than 2 arc seconds can be obtained in this manner. For example, in a practical embodiment of base station 2, in which the wobbling surface beam spans an opening angle α (alpha) of ±5°, a vertical angular resolution of 0.17 arc seconds was obtained.

[0175] The high precision and the simple and therefore inexpensive mechanical construction make it possible to use the disclosed measurement system in particular in applications such as road construction and / or for the definition of virtual guiding lines.

[0176] Figure 14, in contrast, shows that the active target 3 is attached to the kinematic centre of the rolling element 69 of the road roller as well as to the screed 70 of the road finisher. The screed is used to level the hot asphalt pavement 68 to a predefined height, which should be set by an imaginary guide line.

[0177] The measuring system disclosed above now makes it possible, due to the high accuracy obtained, to determine the so-called slump when the road roller repeatedly passes over the still hot pavement, i.e. to show how strongly the road pavement is compacted by passing over it. This in turn makes it possible to directly display the degree of compaction of the road pavement to the machine operator. Corresponding output means are provided for this at the active remote station. Advantageously, as illustrated, at least two active targets or active remote stations with two receiving points are attached to the screed, which make it possible to determine the absolute height.

[0178] FIG. 15 shows how a virtual string line 64 with two base stations 2a and 2b and a stationary target Rx can be provided between them. Here, two virtual planes 65a and 65b are determined for the base station 2a, and two virtual planes 65c and 65d are determined for the base station 2b. Here, the virtual planes 65b and 65c include the respective connection lines of the base stations 2a or 2b to the stationary target Rx, which are arranged between them. In order that the virtual planes 65b and 65c are completely defined, furthermore, a desired direction can be defined perpendicular to the connection lines. That is, a desired lateral inclination of the virtual planes connecting the base stations and the targets between them is defined. Now, based on these virtual planes, an interpolated plane can be defined or a virtual guide line can be defined. Thus, the interpolation points for the interpolated plane or guide line can be provided by the stationarily arranged active target 3, i.e. by the stationarily arranged active remote station 3. This is significantly easier to build and therefore cheaper than the base station, even in the case of the use of a base station according to the invention with a wobbling areal beam.

[0179] 16 shows a top view of a roadwork 67 with a road finisher 61 and active targets 3 attached to its screed, and shows how a virtual guide line 64 constructed according to the invention using active remote stations Rx as interpolation points can be used for height and attitude determination. It should be mentioned that optional absolute position determination can be omitted at least for height control if additional information such as the intersection of direction angles and the planned course of the vehicle travel are mixed or if the odometer values ​​are calculated by subtracting from this information. Nevertheless, the control parameters required for the interpolation and smoothing of the guide variables at the transition points of the segments can be determined sufficiently accurately.

[0180] Although the applicability of the measuring device of the present invention for the guidance of vehicles and machines and its method of application have been clearly described above, it should be emphasized that this measuring device also offers advantages in many other applications.

[0181] For example, the measuring device can be used, inter alia, instead of a dual slope laser operating on a construction site, where it is particularly advantageous to set the tilt of the virtual laser plane at the active target, allowing any setting of the tilt axis at the active target.

[0182] Moreover, it is rather conceivable here that different users work with different orientations, and applications are possible, for example, in the leveling of conical surfaces for conical deposits of material, which would otherwise require expensive special lasers.

[0183] It should be mentioned that, as in the case of the multi-cross laser, it is also possible to project multiple virtual planes standing perpendicular to one another and to orient them by active targets, without the need to mechanically rotate the base station. These properties are also extremely advantageous for industrial surveying, when orienting machines and shafts.

[0184] The measuring device can furthermore advantageously be used for the internal position control of segments in tunnel boring machines or as a central component of innovative channel construction lasers as well as for deformation measurement in monitoring applications.

[0185] Thus, inter alia, a measuring device for position determination is described, which consists of at least one object, the position or orientation of which is to be determined, at least one active target, which is spatially fixedly associated with said object, and at least one base station, within whose detection range the active target is located, characterized in that the base station generates a wobbling area beam, the normal of which rotates around a rotation axis by a constantly known rotation angle, and the wobbling movement is defined by the incidence of the area beam on the active target at least twice per rotation of the normal, the rotation axis standing with respect to the normal of the area beam at a predefined, substantially constant tilt angle, which is not parallel to the normal of the area beam.

[0186] A corresponding measurement arrangement is also disclosed, in which at least two angular positions of rotation of the normal of the surface beam about the axis of rotation at two points of incidence are used to calculate at least one direction angle with respect to the polar coordinate system of the base station.

[0187] Further, a corresponding measurement device is disclosed in which the active target is configured to calculate at least one vertical angle with respect to a polar coordinate system of the base station.

[0188] Further, a corresponding measurement device is disclosed in which the active target is configured to calculate at least one horizontal angle with respect to a polar coordinate system of the base station.

[0189] Further disclosed is a corresponding measurement apparatus in which the base station includes a rotating beam deflection component.

[0190] Further disclosed is a corresponding measurement device, in which the base station includes an areal beam expanding component.

[0191] Further, a corresponding measurement device is disclosed in which the base station includes an optoelectronic beam transmitting element, the radiation of which is collimated, deflected by a rotating beam deflection component, and expanded by a surface beam expanding component to form a wobbling surface beam.

[0192] Furthermore, a corresponding measuring device is disclosed, in which in the base station means are provided for modulating the optoelectronic beam transmitting elements with an angle-encoded data signal.

[0193] Furthermore, a corresponding measuring device is disclosed, in which in addition to the angle data also further auxiliary data are transmitted.

[0194] Further disclosed is a corresponding measurement device, in which the transmitted assistance data includes the attitude of a tilt compensator in the base station.

[0195] Further disclosed is a corresponding measuring device, in which the transmitted assistance data includes a unique identifier (ID or serial number) of the base station.

[0196] Furthermore, a corresponding measuring device is disclosed, which is equipped with an active target for determining the angular position of the rotation of the normal to the surface beam about the rotation axis from the radiation of the surface beam modulated by an angle-encoded data signal and auxiliary data at the time of incidence and from the temporal center of gravity.

[0197] A method is also described for determining the height and attitude of a vehicle by means of a measuring device for optical or quasi-optical position determination, which includes at least one active target fixedly associated with the vehicle and at least one base station within whose detection range the active target is located, and at least one other stationary active target is provided, the connection line between the base station and the stationary active target straddling a segment of a virtual guidance wire and a virtual plane with a predefined lateral inclination, in which the vehicle, at its working height, is guided using the orientation angle of the base station, obtained by the active target, in a manner similar to that of a conventional guidance wire.

[0198] Advantageously, in such a method for determining the height and attitude of a vehicle, a plurality of alternating segments made up of base stations and stationary active targets form a chain of segments of a virtual guide wire.

[0199] It should further be mentioned that, advantageously, in order to determine the control parameters required for the interpolation and smoothing of the guidance variables at the segment transitions, additional information such as the intersection of direction angles is mixed with the planned course of the vehicle travel or the odometer is subtracted and calculated.

[0200] It should be pointed out that in many places so far, base stations for generating a wobbling area beam have been mentioned, in which the normal of the area beam rotates around a rotation axis with a rotation angle that is always known, and the wobbling movement is defined by the incidence of the area beam on an active target at least twice per rotation of the normal. This rotation axis stands with respect to the normal of the area beam at a predefined, substantially constant tilt angle that is not parallel to the normal of the area beam. Such a wobbling movement generated by the rotation of the normal to the area beam is particularly advantageous, since it is easily generated and detected, as is clear from the above description. However, it should be pointed out that in some cases other movements are possible. This is done, for example, by the optical element used for the beam tilt, for example a conical mirror or a plano-concave axicon, not simply rotating around an axis parallel to the axis of the incident beam, but by superimposing a more complex movement. For example, as mentioned above, the rotation of the normal can be combined with an additional tilt caused by an actuator. In that regard, one should recall the precession of a gyroscope, which likewise need not be perfectly regular.

[0201] However, it should be emphasized that certain information can also be transmitted in other ways, for example wirelessly or by wire, but where angle information is transmitted, it is advantageous that the latency is precisely known.

Claims

1. a measuring base station from which measuring radiation is emitted into an area beam, the base station is configured for wobble movement of the area beam; by said wobble motion, the orientation of the normal of said surface beam is changed in a known manner such that the orientation of said normal is repeatable. Base station.

2. the base station is configured to generate the wobble motion of the area beam such that the normal of the area beam periodically repeats its orientation; 2. The base station of claim 1.

3. the base station having a rotatable beam deflection means; A base station according to claim 1 or 2.

4. said base station is adapted to be used with at least one active remote station and generates a wobbling movement such that the normal of said area beam is not parallel to said normal but circulates around a rotation axis standing at a predefined, preferably constant, inclination angle to said normal with a phase angle known as a function of time, in order to sweep said active remote station at least twice per revolution of said normal of said area beam, 4. The base station of claim 3.

5. the base station having a beam expanding means; A base station according to any one of claims 1 to 4.

6. The base station an optoelectronic element for emitting measuring radiation; a collimator for the radiation of the optoelectronic component; It has Additionally, a beam expanding means is provided, the beam expanding means being configured to expand radiation emitted by the optoelectronic element emitting measurement radiation, in particular light emitted as measurement radiation, into a wobbling area beam, A base station according to any one of the preceding claims.

7. The base station includes a tilt sensor or a tilt compensator.

7. The base station of claim 6.

8. the base station comprises means for modulating the measurement radiation emitted by the optoelectronic component with a data signal, said means advantageously encoding information consisting of at least angle information, the tilt of a tilt sensor, a unique identifier of the base station, the temperature of the base station and / or the battery state of the base station. A base station according to any one of the preceding claims.

9. At least one base station according to any one of claims 1 to 8 and at least one associated remote station, preferably at least one associated measurement beam receiver as an active remote station. A measuring device having:

10. 1. A measurement beam receiver comprising: The measurement beam receiver is adapted to receive a beam from a base station according to any one of claims 1 to 8, and advantageously the measurement beam receiver comprises: is adapted to determine, in response to repeated detection of a wobbling area beam, advantageously a time point of said detection and / or at least two angular positions of said area beam normal rotated due to the wobbling of said area beam at the time point of said detection, and to determine at least one angle relative to a polar coordinate system of said base station or data associated with said angle.

13. A measurement beam receiver comprising:

11. the measurement beam receiver is configured to decode radiation modulated with an angle-encoded data signal and possibly auxiliary data to determine the angular position; and / or the measurement beam receiver is configured to calculate at least one vertical angle with respect to a polar coordinate system of the base station; and / or the measurement beam receiver is configured to calculate at least one horizontal angle with respect to a polar coordinate system of the base station; 11. The measurement beam receiver of claim 10.

12. the measurement beam receiver has at least two spaced apart photosensitive elements that are operatively positioned at different heights; the measurement beam receiver is adapted to resolve measurement ambiguities and, advantageously, also to determine the distance from the base station from the time signature of the sweep of the photosensitive element; Measurement beam receiver according to claim 10 or 11.

13. A method for guiding a moving object, in particular a vehicle, comprising: The method comprises using a base station, which jointly forms a transmitter-receiver-measurement device, and at least one active remote station, which is fixedly associated with the moving object, At least one other active remote station is installed at the station; determining virtual connection lines between said base station and said other fixed installed and mobile active remote stations; Next, determining guidance data for guiding the moving object with reference to beam detections and the virtual connection lines associated with the active remote stations that are fixedly associated with the moving object; Advantageously, the guidance data is determined by determining a plane in which the virtual connection lines are located between the base station and the stationary active remote station, the plane additionally having a defined lateral inclination, More preferably, the guidance data is determined by determining a target guidance line in the plane, and particularly preferably, guidance data is determined for guiding the moving object along the plane. A method for guiding a moving object.

14. configuring said chain of segments of a virtual connection line such that base stations and active remote stations installed at fixed locations alternate along the chain, said chain of segments forming a virtual induction wire, A method for guiding a moving object according to claim 13.

15. smoothing the guidance data determinable for the various segments, preferably with reference to additional information, particularly preferably with reference to the intersection of the planned course of the taxiway with the direction angle and / or with reference to the odometer value, and / or carrying out an interpolation at least at the transition points of the segments, Advantageously, as guidance data, control parameters for the automatic movement of said moving object are determined. A method for guiding a moving object according to claim 14.

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