Measuring apparatus 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] This invention relates to a broader conceptual claim and therefore deals with measurement. [Background technology]

[0002] Measuring devices capable of measuring the position and / or orientation of an object and / or individual coordinates relative to a base station are applied in many fields, such as industrial surveying and construction surveying, construction machinery control, and the detection of real objects for the creation of virtual reality. For this purpose, many measuring or surveying devices are known.

[0003] Therefore, many different technologies have been developed, such as tachymeters, laser trackers, rotating lasers, and real-time kinematic GNSS receivers. Some of these enable simultaneous use at many measurement locations with multiple relatively inexpensive devices, for example, multiple remote stations to one base station, but they have a series of problems. These problems include excessively low measurement accuracy, reception via multiple paths, shadowing in street canyons, and the availability of correction services and satellite systems.

[0004] Therefore, in many applications, a proven approach involves a central base station that emits a rotating or fan-shaped beam. A suitable beam receiver allows for the estimation of the receiver's position relative to the base station. In principle, a passive retroreflector, for example, could send the beam back from the receiver to the base, where it could be determined where the beam was reflected from. However, so-called active receivers are easier to use and are now widely used in surveying. In an active receiver, a photosensitive element can generate and evaluate an electrical signal in response to the reception of light. Here, the sign at which the beam is detected by the beam receiver relates, 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 configured. For example, the beam receiver may be equipped with an elongated or point-shaped photosensitive element, and the base station can emit light as a fan-shaped beam or as a single beam, at a constant intensity or with temporal modulation. It should be noted that the beam may be visible or invisible, and in some cases, beams in the high-frequency range may be used. For the sake of simplification, unless it becomes clear otherwise, this specification generally refers to position determination being performed “optically” or at least “quasi-optically,” even when invisible or high-frequency radiation is used in some cases.

[0005] In the described system, which includes a central base station, a range of approaches already exist to reduce costs and improve accuracy and availability. This is illustrated exemplified by the conventional base station known from the prior art, shown in Figures 1a–1d.

[0006] Figure 1a shows a base station with three fan-shaped beams radiating from a rotating base, disclosed in the applicant's US7394527 and US5767960, which allows an active remote station, i.e., an illuminated active target, synchronized wirelessly or wired, to calculate the spacing, height, and horizontal angle of the active target in cylindrical coordinates with respect to the base station from a time-sequence of incidences of the three fan-shaped beams onto the active target.

[0007] Figure 1b shows the base station of EP1434029 with three planar beams radiating from the center of rotation, which allows for the calculation of the base station's horizontal and vertical angles in polar coordinates using a suitable active target.

[0008] Figure 1c shows a prior art apparatus according to US4441809, whose characteristics substantially correspond to those of Figure 1a, but which requires at least two active targets to determine multiple elevation angles.

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

[0010] The conventional approaches shown in Figure 1 share the common characteristic of being based on a rotating laser optical system that emits at least two to three fan-shaped beams, enabling the determination of up to two directional angles with respect to an active target. For this purpose, time measurements of the incidence time of each fan-shaped beam are used. These approaches also make it possible, at least in principle, to create almost any number of virtual (laser) planes across the measurement space centered on the base station, using the measured vertical and horizontal angles. In other words, measurements become possible at many heights.

[0011] However, these known devices and the required receivers are often structurally undesirably complex, especially when high precision is required. That is, the precision of such optical devices is determined, in particular, by the precision with which light is emitted through the base. Herein, the precision of the mechanical construction is involved, but is not limited to, which leads to the high cost of high-precision base stations. Regarding the range, it should be noted that in many cases the beam should be clearly visible. This allows the receiver to be placed relatively easily 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 constrained to ensure eye safety. This, too, reduces the range.

[0012] Furthermore, the illustrated approach is based, among other things, on the fact that two or more fan beams must be guided through different (cylindrical) optical systems, but these optical systems inherently have differing and non-compensating imaging errors. Therefore, since the required flatness or parallelism of the fan beams is extremely critical, determining high accuracy of the vertical angle is impossible without laborious, costly, and time-consuming factory calibration in multiple degrees of freedom. Moreover, synchronization between the active receiver and the base station is often simply loose or completely absent, and if high angular accuracy is desired, this also imposes high demands on the parallelism of the rotating laser head. Typically, to obtain angular accuracy of a few arcseconds for the vertical and horizontal angles, a parallelism value of approximately 0.001% to 0.0001% is required. Due to these demands, the base station must rely on expensive and fragile bottom friction bearings and a large flywheel mass, which reduces robustness and raises questions about its practical suitability in many applications. In particular, the base stations are becoming larger and heavier, which causes both the system price and the overall user cost over its lifespan to skyrocket.

[0013] Therefore, it would be desirable to enable improvements here. In particular, the prior art approaches shown in Figures 1b and 1d remain very popular with users in the fields of construction machinery control and industrial surveying.

[0014] Therefore, automated tracking distance measuring instruments have already been developed for specific applications, in which individual remote stations are tracked by a base station. These individual remote stations may be passive retroreflectors or active receivers, or active transmitters if 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 tachymeters for land surveying, remain very popular, but they are not only expensive but also have the drawback of only being able to track individual targets per base.

[0015] In certain applications, such as the advantageous overall, and preferably even autonomous, road paving tandem—that is, the control of a series of road finishers and multiple roller construction machines—this would result in almost exorbitant costs, because each object to be tracked or measured, or each measurement point on it, would need to be provided with its own base station.

[0016] In the field of construction machinery control, it is often necessary not only to measure position or location, but also to precisely control height. This is required, for example, in road construction, where, for instance, the installation height of the road surface or the thickness of the road surface layer needs to be controlled. Many systems used for this consist of a rotating laser and a so-called machine receiver, i.e., a linear receiver suitable for the rotating laser on road construction machinery. While this enables precise height control, it is tied to a single laser plane, which can be a major drawback in uneven terrain.

[0017] Therefore, conventionally, guidance wires or reference lines were often used in uneven terrain, but their installation was equally labor-intensive. Even the approach of using base stations with integrated receivers to replace actual reference lines with virtual guidance lines typically still requires considerable equipment effort.

[0018] Therefore, for example, European Patent Application Publication No. 2998699 proposes a method for guiding the installation height and controlling the layer thickness of road construction machinery. The disclosures of this document are incorporated by reference. This method, known from the prior art, is briefly shown with reference to Figure 13.

[0019] In this known method, a station is used that is a rotating laser transceiver, which can simultaneously be used as a base station and as a receiver of radiation from another station. These are used in this known method to replace the otherwise commonly used guide wires for controlling the installation height of the road finisher with a chain-like arrangement of multiple rotating laser transceivers 66a-66g (TRX) leveling each other. This is done by defining a virtual guide wire segment by segment along the road 67, referring to a laser plane 72 generated by the base station. The rotating laser transceivers act as interpolation points for this guide wire. Interpolation, and possibly smoothing, is performed between these interpolation points to widen their spacing, which should reduce the effort required for calibration for a given section.

[0020] Such systems should be cheaper than the cost of surveyors calibrating sections several kilometers long using conventional guide wires, so it seems the cost of the system would be quickly amortized. However, even in the case of interpolation, these systems are structurally particularly complex, as they require many rotating laser transceivers to level each other.

[0021] Furthermore, this known system has another drawback. For example, the constraints in the height measurement range are significantly reduced by the described chain-like arrangement, but are not completely eliminated. This is shown in FIG. 12, where a typical configuration of a hot asphalt installation with two machines is shown.

[0022] Receiving the laser surface on uneven terrain takes an extremely long time, and thus it is clear that, in principle, road construction machines require particularly costly laser receiver lines. In this regard, reference is hereby made, in particular, to the specification of the applicant's US Patent Application Publication No. 2018 / 0259332, which is also fully incorporated herein by reference. However, the length of these devices can lead to measurement inaccuracies when the machine vibrates, for example, in the case of use on the screed of a road finisher or in the suspension of the rolling elements 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 surface, and the radiation is emitted only to a single surface. Therefore, a separate transceiver must be provided for each interpolation point of the virtual guidance line of the prior art. This transceiver simultaneously includes both a base station and an active target. Therefore, these devices are restricted to specific purposes of use and are hardly suitable for universal applications.

[0024] It would be advantageous to provide an inexpensive measurement system, especially with high accuracy at the same time.

[0025] It would also be advantageous to be able to provide a virtual guiding wire (a "string line") at a low cost. Furthermore, it would be advantageous to be able to use a base station that can be used for a wider range of purposes. Furthermore, it would be advantageous if the constraints imposed in the height measurement range were less than those known in the prior art.

[0026] In particular, in order to further reduce system costs, it would also be advantageous to have a measuring device and method that can enable interpolation points of a virtual string line without the need for a particularly expensive base station.

[0027] It would also be desirable to present an improved measurement arrangement and / or method for optical or quasi-optical position determination.

[0028] It would be desirable to obtain at least partially at least one of the advantages outlined above.

Summary of the Invention

Problems to be Solved by the Invention

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

Means for Solving the Problems

[0030] The above problems are solved by the independent claims.

[0031] Some advantageous embodiments are described in the dependent claims. Other advantageous embodiments and other solutions having inventive step are described in the specification.

[0032] In other words, in the initial basic consideration of the present invention, a base station for measurement is presented, from which a measurement beam is radiated onto a plane, and the base station is configured for the wobbling motion of the planar beam as follows: that is, the orientation of the normal of the planar beam is changed in a known manner, and this orientation of the normal occurs repeatedly.

[0033] Therefore, the initial fundamental understanding is that the vertical angle can be determined by the controlled, deliberately set, wobbling motion of a planar beam in a known manner, or, using further information, the height can be determined particularly easily. For example, if a base station emits a beam that is detected by a receiver, the height of the receiver relative to the height of the base station can be easily determined.

[0034] To understand this, let's assume that the planar beam is fixed and standing upright, that is, that the orientation of the planar beam does not change. In such a case, receivers currently located within the planar beam, i.e., receivers currently being irradiated by a beam extended into the surface, will continue to remain within the planar beam.

[0035] In contrast, if the planar beam wobbles, this causes the beam to gradually change its height at the receiver's location in proportion to the wobbling motion. More precisely, the beam moves up and down between its highest and lowest heights at a given location away from the base station, i.e., in proportion to the wobbling motion. For simplicity, assuming a periodic wobbling motion, and further assuming that the beam receiver is fixed in place at a given location away from the base station at a height between the highest and lowest heights reached by the planar beam, then the planar beam sweeps the receiver twice during one wobbling cycle. That is, once when the planar beam descends from top to bottom and reaches the receiver's height, and again when the planar beam ascends from bottom to top and reaches the receiver's height. If the receiver's height is very close to the highest height, only a short time will pass between the first sweep observed during the ascent and the second sweep when the planar beam descends again. The same applies when the receiver's height is very close to its minimum height, and the descending planar beam has just swept over the receiver's height for the first time. Even then, the time it takes for the planar beam, which initially descends to its minimum height, to rise back up to the receiver is only short. In contrast, if the receiver's height is approximately midway between the minimum and maximum heights that the planar beam can reach at a given distance, and the wobble velocity is the same, it will take a correspondingly longer time for the receiver to be swept over again. Therefore, if the wobble behavior and the distance from the base station are known, the receiver's height can be estimated from the sweep time interval.

[0036] It should be noted that when a receiver is repeatedly swept at a given height under periodic wobbling motion, two different intervals can occur between two sweeps. The first interval corresponds to the time between a sweep when the planar beam is moving from top to bottom and a sweep when it is moving from bottom to top, and the second interval corresponds to the time between a sweep when it is moving from bottom to top and a sweep when it is moving from top to bottom. Together, the two intervals correspond to the wobbling period. However, the same combination of intervals can be observed near both the maximum and minimum values ​​of the height. This can sometimes lead to ambiguity if it is not clear whether the planar beam is tilting upward or downward precisely due to the wobbling motion, but this can be resolved in various ways.

[0037] Furthermore, it will be clear that the maximum height that a planar beam can reach under a given inclination, as caused by wobbling, is related to the distance from the base station. Here, the time interval is related to how close the receiver's height is to the minimum or maximum height that the beam can reach at this distance under a given inclination, as caused by wobbling.

[0038] Therefore, if the distance from the receiver to the base station is unknown, 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 the ambiguity of the height determination. There are various possibilities for this.

[0039] In some cases, to obtain clarity regarding height, the measurement space can be restricted to, for example, half the space through which the coordinate center of the base station passes its dividing plane, and as a result, measurements can be performed only at heights above the horizontal or only at heights below the horizontal. At the receiver, it can also be determined, for example, by the use of two photosensitive elements, whether a wobbling motion at that location results in an upward or downward movement of the planar beam. It should be noted here that the clarity obtained, once achieved, is maintained as long as the movement of the active remote station relative to the base is tracked. This is sufficient to guarantee clarity over the long term. This tracking is particularly advantageous when it must be considered that ambiguity cannot always be resolved even with a large number of photosensitive elements, for example, due to the temporary shadowing of one or more photosensitive elements of the active remote station.

[0040] Advantageously, the photosensitive elements are positioned at a known interval, overlapping and separated so that, in principle, both photosensitive elements are swept. In such cases, it is first possible to determine from a series of sweeps whether the upper photosensitive element was swept first, followed by the lower photosensitive element, or vice versa. That is, from the course of the reception event, it is possible to determine whether the planar beam is currently rising or falling due to wobbling at the receiver's location. Furthermore, the distance between the receiver and the base station can also be determined here. It should be noted that the effort required for the equipment to move two sufficiently large photosensitive elements in the optical receiver and the time required to evaluate the signal of these receivers are very short. Moreover, such receivers can be configured to withstand vibrations, so that even strong vibrations such as those generated by road construction machinery do not interfere with uncontrollable vibrations.

[0041] In principle, the base station emits radiation, and the remote station is configured as a receiver that receives the radiation emitted from the base station. The receiver is an active remote station, and typically contains photoelectronic elements such as photodiodes, which generate an electrical signal in response to the incidence of radiation. This electrical signal is then processed in principle at the active remote station, i.e., it is signal-tuned, so that a digital signal is determined in response to the analog received signal, and in response to this digital signal, other variables such as the angle or coordinates relative to the base station are calculated.

[0042] The term "light beam" emitted by a base station here does not simply refer to visible light radiation. Arrays of individually or collectively driveable elements sharing the same downstream optics, such as conventional laser diodes, solid-state lasers, LEDs, and collimator optics that emit visible or invisible light, particularly in the infrared, as well as Gunn diodes and other HF radiators in the quasi-optical wavelength range, are referred here as suitable sources of such radiation included in the term "light beam."

[0043] The emitted radiation passes through a plane, and this plane wobbles in proportion to the present invention. In some cases, due to inaccuracies or wear of the rotating bearings, a kind of wobbling motion may be observed in known base stations with rotating beams, but this should be suggested that this is not wobbling motion, and in particular, that is, not known wobbling motion, for which there are parameters that allow the current orientation of the normal to be obtained. Unlike wobbling motion, in wobbling motion, the orientation of the normal of the planar beam does not change in a known controlled manner, much less change so that the orientation of the normal is repeatedly performed as known.

[0044] It should also be noted that the wobbling motion of the present invention, in principle, brings about a considerable change in the inclination of the planar beam. For a planar beam that is horizontal on average, it is clear that the wobbling motion brings about an inclination of at least ±2.5°, preferably ±5°, more preferably at least ±10°, and particularly preferably at least ±15° with respect to a perfect circle of 360° with respect to the horizontal line.

[0045] It should be emphasized that, in optical or quasi-optical wavelength spectra, the sole planar beam emitted by the base station, accompanied by radiation in the form of a planar profile beam, planar beam, or fan beam, is already sufficient to determine the two directional angles relative to the base station, namely the vertical angle λ (lambda) and the horizontal angle ψ (psi) during the sweep of the active remote station. In this regard, it should also be noted that, in the case of a fixed or nearly fixed remote station, the normal can repeatedly assume the same orientation, so the values ​​can be averaged, thereby improving accuracy.

[0046] There are various ways in which the orientation of the planar beam normal can be changed in a known and controlled manner. For example, a complete rotation or a motion that moves back and forth between two endpoints (scanning or oscillating) may be set. The scanning motion has the advantage of sweeping a particular region more frequently. In contrast, a complete rotation is, in principle, structurally easier to achieve.

[0047] In principle, the beam path passes through the same optical components of the base station under two beam passes of rotational or scanning motion, and therefore, most of the errors that would otherwise be particularly relevant cancel each other out, and it is also possible that linearity errors, especially those related to vertical angle measurement, can cancel each other out. Thus, it becomes possible to detect the vertical angle with accuracy down to the sub-arcsecond range, with only a rapid one-dimensional calibration of the vertical angle offset.

[0048] While it is not essential to use an active receiver as an active remote station, it should be emphasized that in some cases an active remote station can be made active by itself transmitting a beam. In this case, the base receives radiation only from a wobbling surface, for example, by connecting a suitable receiving optical system in front of a photosensitive element. That is, wherever otherwise referred herein as an optoelectronic beam transmitting element, in the case of such reversal between the transmitter and receiver, an optoelectronic beam receiving element such as a photodiode, APD, SiPM, detector array, or CCD may be provided instead, and vice versa. In this case, the beam direction is reversed, which would otherwise be the normal direction. The planar beam represents the directional characteristics of the received optical beam, not the directional characteristics of the transmitted measured radiation. This is obviously possible not only in the base station but also in the remote station, which is configured in principle as a receiver. This will not be further discussed in all subsequent sections, but it has the advantage of allowing radiation to be directed precisely or roughly towards the base, which reduces the risk to people at a given beam intensity as needed.

[0049] Furthermore, in the base station, both the optoelectronic beam transmitting element and the optoelectronic beam receiving element can be simultaneously positioned at the focal point 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, thereby enabling directional measurements on a highly reflective passive target. This passive target is, for example, a corner / cube reflector (cat's eye) used in total stations. In addition, pulse time measurements become possible to determine a complete set of 3D coordinates. Even in such cases, the planar beam will wobble. This is considered novel in itself, as it allows multiple base stations to calibrate each other, for example, and enables 3D measurements comparable to those of a robotic tachymeter. An advantage over previously known base station transceivers is that, compared to two rotation axes in conventional tachymeters, here the significantly simpler optomechanics requires only one precise rotation axis. As will be further explained below, the usefulness of such a device for segment chains forming guide lines is explicitly disclosed as being particularly advantageous and inexpensive, and is also considered novel in itself.

[0050] It should be noted that equipping a base station for radiation reception, such that it receives radiation only from specific directions, and equipping an active remote station for beam emission, is itself considered patentable. This is especially true when the operation is performed on a wobbly surface, in which case the base station has wobbly receiving characteristics.

[0051] In other words, as is clear from the above description, a measuring device for optical or quasi-optical position determination can be provided, which has at least one active target spatially fixedly associated with an object whose position or orientation is to be determined, and at least one base station, wherein the active target exists in the region of the base station that is detectable by the measurement, and the base station generates a wobbling planar beam.

[0052] It should also be explained that the terms "plane" or "planar beam" refer to a wide variety of beam arrangements. Therefore, in this invention, for example, a planar beam profile may be used, which is, for example, a flat plane that is advantageously substantially, i.e., undistorted except for imaging and abutment errors. However, in this invention, a conical surface having a circular, elliptical, or slightly wavy basic profile may be used in the conical mirror described below or in the axicon total reflection conical depression described below, and a fan beam or multiple fan beam is also referred to, which is, for example, a coplanar multiple fan beam caused by shadowing. Furthermore, a planar beam of the above type that is distorted by imaging and abutment errors is also referred to. Despite such a broad interpretation of this term, an ideal flat plane is assumed, particularly when mathematical formulas are presented, in order to facilitate the understanding of the presented formulas. However, it should be noted that planar beam profiles, fan beams, or beams circulating in a plane (assuming liberation from wobble that is not further superimposed) are particularly advantageous in this regard, and this is also true in detail when the advantageous variants are distorted by imaging errors and / or abutment errors.

[0053] The wobbling motion is advantageously realized and defined by the fact that the endpoint of the normal to the planar beam circulates around an axis that is not parallel to this normal, and more specifically, is always known, advantageously, circulating at a constant or substantially constant inclination angle with respect to the non-parallel axis. Here, the phase of the circulation of the planar beam normal around the non-parallel axis is also always known, and the planar beam is incident on the active remote station, i.e., the active target, at least twice for each periodic circulation of the normal, and more specifically, at the normal phase angles of ψ1 and ψ2 (note that these phase angles will hereafter also be referred to as rotation angles or angular positions). As is known from gyroscopes, the normal follows a kind of precession.

[0054] On the one hand, non-parallel axes are generally vertical, and on average, this causes the planar beam to wobble around the horizontal plane. The vertically oriented axis may be the axis of rotation of an optical element, i.e., a rotating beam deflection component for radiation emitted by the base, in cases where the wobbling motion is realized as a periodic wobbling motion by rotating the optical element.

[0055] However, it should be noted that it is not always necessary to orient non-parallel axes precisely vertically. In particular, it is possible to compensate for the non-perfect vertical orientation of non-parallel axes, which eliminates the need for particularly time-consuming setup and helps avoid errors if the installed base itself gradually tilts during measurement due to reasons such as the ground being too soft. In other words, in this respect, it should be emphasized that while non-parallel axes are usually substantially vertical, 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 in time during which the active remote station is swept when the planar beam normal circulates around a non-parallel axis are available for calculating at least one direction angle with respect to the polar coordinate system of the base station. It would be advantageous if the active remote station, i.e., the active target, were 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 understood that the planar beam normal can easily perform repeated orientation by periodically passing through its own orientation. Therefore, in an advantageous embodiment, it is proposed to configure the base station to generate a wobbling motion of the planar beam so that the planar beam normal periodically repeats its own orientation. Particularly advantageous periodic motion can generally be achieved by a rotation such as the precession of the planar beam normal around a vertical axis.

[0058] Here, in order to easily realize a wobbling planar beam motion, the base station only needs to include a rotating beam deflection component. Examples of this include a rotating transmissive angle-refracting prism, a rotating mirror positioned at an inclination with respect to a vertical axis or rotation axis, and an axicon or conical optical system that can be formed as a conically polished lens that images a point source onto a line along the optical lens axis or converts a laser beam into a ring, and are referred to as such as other rotatable devices of multiple optical components that can rotate and deflect a collimated beam at an angle a about its propagation direction. It is clearly advantageous for the base station to include a rotating beam deflection component because it can be easily implemented using such elements.

[0059] Furthermore, since it is structurally particularly well realized, it is advantageous that the base station is configured to be used with an active receiver, and that the wobble motion is generated as follows: namely, the normal of the planar beam is not parallel to this normal, but circulates at a known angle of rotation around a rotation axis that is fixed at a predetermined, at least substantially constant, angle of inclination with respect to this normal, and that the planar beam is incident on the active receiver at least twice for each rotation of the normal, thereby generating a wobble motion.

[0060] As mentioned above, many beam profiles are possible. It is advantageous to use beam expansion components to obtain these from conventional beam sources such as laser diodes, solid-state lasers, or LEDs. Therefore, it is advantageous for the base station to have beam expansion components or beam expansion means, such as components that expand the beam into a planar beam. In some cases, it has been noted that the beam can be expanded to form one or more fan shapes. Furthermore, it has been noted that the spatial distribution of emission can be influenced by shadowing, selective absorption, etc.

[0061] Beam extension components for generating a planar beam can, for example, have the form or function of a conical mirror. This may be configured with any conical angle, preferably 90°. Similarly, the use of axicons, for example, a plano-concave axicon with internal reflection and lateral extraction via the sheath surface, is disclosed, and it is also mentioned that cylindrical optical systems can be used, as well as any other combination of suitable optical components.

[0062] Furthermore, the base station may include an optoelectronic beam transmitting element, with an optical element positioned after this optoelectronic beam transmitting element, and / or the optoelectronic beam transmitting element may be integrated with the optical element, thereby allowing the emitted radiation to be collimated to a specific aperture angle, or, advantageously, to a diffusion as parallel as possible. Possible for this include laser diodes, solid-state lasers, LEDs, and arrays of individually driveable elements sharing the same collimator optics, and alongside these, in the case of quasi-optical wavelength ranges, Gunn diodes or other HF radiators are also possible.

[0063] Similarly, both the optoelectronic beam transmitting element and the optoelectronic beam receiving element may be set to be simultaneously focused into a collimation optical system, for example, by a polarizing beam splitter equipped with a λ / 4 plate. Thus, the base station can perform direction measurements on a highly reflective passive target such as a corner cube reflector (cat's eye) used in total stations, and alongside this, it can perform pulse propagation time measurements to determine the entire 3D coordinate system. Thus, the base station can, for example, calibrate itself or perform 3D measurements comparable to a robotic tachymeter. However, the advantage here is that, compared to two rotation axes in a tachymeter, the significantly simpler optomechanics requires only one precise rotation axis.

[0064] Even more advantageously, the collimated beam is deflected by a rotating beam deflection component and expanded by a planar beam expansion component to form a wobbling planar 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 the radiation, further comprising a rotating beam deflection component, which is configured to deflect the light emitted from the optoelectronic optical radiation transmitting element to form a wobbling planar beam. This clearly makes it possible to configure the base station particularly easily.

[0066] An example of a planar beam normal circulating around a vertical axis was presented above. It was explained that this axis does not necessarily need to be perfectly vertical. It has already been pointed out that it is possible to compensate for orientations that are not perfectly vertical. Therefore, advantageously, the base station of the present invention is provided with a tilt compensator. The tilt compensator can mechanically force horizontal orientation, for example, by correcting an incorrect orientation using an actuator, and in some cases by repeatedly correcting a changing incorrect orientation using an actuator. However, it should be noted that advantageously, it is sufficient that the tilt angle of the structurally defined axis of the base station, for example, the rotation axis of a rotating optical component, is detected with sufficient accuracy, and the corresponding information is used for evaluation. Therefore, the basic tilt of a wobble-free planar beam, i.e., the orientation of the center of the planar beam, can be compensated in two different ways: on the one hand by mechanical orientation, and on the other hand by detection and calculation compensation using measurement techniques. It should be mentioned that detection and calculation compensation using measurement techniques are in principle inexpensive and therefore advantageous both structurally and operationally.

[0067] More advantageously, the base station has means for modulating the optical radiation emitted from the optoelectronic elements with a data signal, which is preferably modulated by an angle-coded 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 the temperature of the base station, the battery status of the base station, etc., and by the orientation of a tilt sensor or tilt compensator. That is, information regarding the current actual tilt of the planar beam, and thus its central orientation, may preferably be superimposed on the radiation emitted by the base station for modulation. Similarly, the current phase in the planar beam normal circulation cycle may be transmitted to an active remote station by an angle-coded data signal. The particular advantage of transmitting the current phase in the planar beam normal circulation cycle, i.e., the current rotation angle of a rotating optical system, i.e., a rotating rectangular prism, which causes wobble of the planar beam by its own rotation, is, in addition to structural simplification by eliminating additional elements for wired or wireless transmission, etc., it is, above all, liberation from latency. In the case of multiplex reception, averaging is possible, and it should be noted that a particularly suitable method for coding rotational angle information is disclosed later. Therefore, the measuring apparatus is advantageously configured to include means for modulating the optoelectronic beam transmitting element with a data signal on which angle coding is performed.

[0068] Therefore, angular synchronization between the base station and the active remote station can be achieved directly by modulation of the radiation of the planar beam with angle-encoded data signals from the base station and selectively other auxiliary information, rather than through interference-prone individual wireless or infrared data transmissions (which are time-offset and simply loosened) as in the past. This device alone can reduce the requirement for rotational parallelism by typically more than two orders of magnitude, and eliminate the costly bearings and flywheel mass that would otherwise be required. Transmitting the rotation angle by loading appropriate information onto the emitted beam for modulation is also advantageous here and is considered novel in itself, i.e., regardless of the wobbling motion of the planar beam. Here, the base station emits a rotating beam or a rotating planar beam or fan, and the current rotation angle at beam reception must be known, in particular to determine the coordinates of the measuring beam receiver. Here, the data signal that is modulated onto the emitted radiation can encode, for example, the current angular position of the rotation axis of the beam deflection component, where the angular position is obtained by an angular encoder coupled to the rotation of the beam deflection component.

[0069] In this regard, it should be clearly noted that certain aspects of the inventions claimed or disclosed herein, particularly optical data transmission via a laser beam with rotational angle data and / or transmission of auxiliary information such as, for example, a unique identifier (ID or serial number), are generally advantageously applicable to the laser transceiver of European Patent Application Publication No. 2998699, and similarly to any rotating laser. These rotating lasers are thereby capable of determining a horizontal angle. This is done without external synchronization, for example, by wireless or separate IR data transmission, or to enable the unique assignment of the received laser beam to the laser transmitter.

[0070] From the above description, it becomes clear how it may be advantageous to transmit additional auxiliary data regarding radiation or planar beams, in addition to angular data, at least intermittently. This could include, for example, the orientation, i.e., attitude, of a tilt sensor or tilt compensator used to retrospectively compensate for the tilt of a base station at and through an active remote station, as well as the transmission of battery status, temperature, etc., which would allow for early identification of potentially critical base station operating conditions when measurements are prolonged. In this case, there is no need for human control at the base station.

[0071] It should be noted that the size of the photosensitive element in an active remote station is typically large enough that a certain amount of time is required for the sweeping of the photosensitive element and, consequently, for the reception of radiation by the base station. This is already true for photosensitive elements with extremely small areas, so as long as the active remote station is configured to calculate and determine the phase position of the planar beam normal obtained during the sweep period, i.e., the angular position of its own rotation around the rotation axis, taking into account the temporal centroid of the beam reception, it becomes possible to determine the direction angle with particular accuracy without any special structural effort in the active remote station.

[0072] In other words, the phase position of a planar beam normal is typically encoded in discrete angular steps. When radiation encoded in these discrete angular steps is received over a long period of time, it is possible to interpolate between multiple discrete angular steps.

[0073] In other words, advantageously, during beam reception, i.e., during the sweep of the active remote station, the discrete angular steps transmitted from the base station and received at the active remote station are interpolated. Alternatively and / or additionally, the beam reception sign can also be evaluated, for example, by optimizing a model of a typical beam reception process using the LMS method or a reasonably trained neural network (KI, AI).

[0074] When the distance between the base station and the photosensitive element is large, beam reception events contain significantly more noise and / or last for only a very short time, so in many cases only one angular step can be decoded at the receiving end. However, even in that case, by considering the wobble velocity and the envelope curve of the received signal, the phase position of the temporal centroid can be estimated with subsampling accuracy, i.e., much more accurately than the encoded angular step. In the corresponding calculations, it is not necessary for the wobble velocity to be known with particular precision, and it is clear that its temporal variation under the above conditions does not significantly affect the measurement accuracy.

[0075] As is clear from the above description, protection is first requested for the base station. However, protection is also requested for the measuring device which includes at least one corresponding base station as described above and at least one active remote station to which it belongs. It should be noted that in some cases, the active remote station may be located on another base station as described, without requiring particularly high structural effort. However, in other cases, and / or additionally, the active remote station may be realized by an active receiver. Here, an active receiver is assumed to exist in which there are active electronic elements, active electronic circuits, or data evaluation units, etc. It should be noted that the measuring system of the present invention with a base station can call upon a plurality of active remote stations, and accordingly, a plurality of active remote stations may belong to the measuring system. In particular, for example, to define a virtual guide line, at least an active remote station provided on a mobile unit and an active remote station provided as a fixed station may be provided.

[0076] As already explained, the ambiguity in height determination can be easily resolved by properly configuring the active remote station. In particular, this can be achieved by using multiple photosensitive elements spaced vertically, in which case, if the spacing between the photosensitive elements used is known, the spacing between the active remote station, such as an active optical receiver acting as an active target, and the base station can be determined at the same time.

[0077] Therefore, an advantageous embodiment of the measuring beam receiver is configured such that the measuring beam receiver has at least two spaced-apart photosensitive elements positioned at different heights during operation, and the measuring beam receiver resolves the ambiguity of height determination from the sweep time sine of the photosensitive elements, and advantageously also determines the distance from the base station. Similarly, it should be noted that in a remote station emitting radiation, at least two beam sources may be provided spaced appropriately apart from each other.

[0078] In particular, in relation to advantageous embodiments, it will become clear that an active remote station, such as an active measuring beam receiver, is specifically modified for use with the base station of the present invention.

[0079] Accordingly, protection is also claimed for the measuring beam receiver. The measuring beam receiver is configured to receive a light beam from the base station, as disclosed herein or as described above, and in particular may be configured to calculate at least one angle relative to the polar coordinate system of the base station in response to the detection of repeated wobbling of a planar beam. This calculation is advantageously performed by determining the time of detection and / or at the time of detection, at least two angular positions of the planar beam normal rotating due to the wobbling of the planar beam. It should be noted that, in principle, it is possible to determine the complete position and possibly orientation of the active remote station relative to the base station using the base station and the active remote station to which the present invention belongs, and that any coordinates can also be clearly determined. In this case, for illustrative purposes, it is not necessary to refer to particularly familiar cylindrical or spherical coordinates with the base station as the origin.

[0080] As is evident from the above description, the measuring beam receiver of the present invention is advantageously configured to determine an angular position by decoding radiation modulated with an angle-coded data signal and optionally with auxiliary data, and / or to calculate at least one vertical angle with respect to the polar coordinate system of the base station.

[0081] Furthermore, the measuring beam receiver is configured to calculate at least one horizontal angle with respect to the base station's polar coordinate system. That is, typically, a signal conditioning unit and / or a digital data processing stage are provided.

[0082] To determine the direction angle with high precision, an active remote station, i.e., an active target, may be configured to determine the angular position of the rotation of the normal of the planar beam around the rotation axis, at the time of incidence, from the radiation of the planar beam modulated with an angle-encoded data signal or possibly auxiliary data, along with the calculation of the temporal centroid of the beam reception for interpolation between transmitted discrete angular steps.

[0083] A particularly advantageous and typical application of the measurement system, light-emitting base and / or the measurement beam receiver of the present invention is to guide moving objects, especially vehicles, such as autonomous vehicles.

[0084] Accordingly, protection is also claimed for a method of guiding a moving object, in particular a vehicle, where a base station emitting radiation and at least one measuring beam receiver fixedly associated with the moving object for that radiation are used. Here, at least one other measuring beam receiver is installed in a fixed position, and a virtual connection line is determined between the base station and the other, installed measuring beam receiver, and then guidance data for guiding the moving object is determined by radiation detection by the measuring beam receiver fixedly associated with the moving object and by referring to the virtual connection line. Advantageously, this is done by determining a plane on which the connection line is located between the base station and the installed measuring beam receiver, which additionally has a defined lateral inclination. Further advantageously, a target guidance line is determined on this plane, and further advantageously, guidance data is determined so that the moving object can be guided along this plane. The lateral inclination can be defined, for example, by an inclination value set by the user, or by the connection line of the base station to other, installed measuring beam receivers.

[0085] In particular, a method is proposed for determining the height and attitude of a vehicle using a measuring device for optical or quasi-optical position determination. This measuring device has at least one active target and at least one base station fixedly associated with the vehicle. Here, the active target is positioned within the detection range of the base station, and at least one other fixed active target is provided, and a segment of a virtual guidance wire and a virtual laser plane having a predetermined lateral inclination are provided across the connection line between the base station and the fixed active target, where the vehicle is guided at its working height using the directional angle of the base station obtained by the active target, similar to conventional guidance wires.

[0086] In this method, advantageously, a chain of segments of virtual connection lines can be configured such that base stations emitting radiation, preferably optical radiation, and fixed, active remote stations, i.e., preferably measuring beam receivers, alternate along this chain, and this chain of segments forms a virtual guidance wire. Here, each base station can be assigned two virtual laser planes, which are calculated from the station's azimuth angle by the respective adjacent fixed, active remote stations or targets.

[0087] Here, the active remote station does not need to simultaneously function as a base station; it may simply be an active remote station that receives the beam. This advantageous configuration significantly reduces the structural effort required to obtain a virtual connection line of a given length, given that the base station ranges are the same, i.e., the radiation capabilities are the same. It should be disclosed as an advantageous variation that, depending on the circumstances, communication between various interpolation points may occur in such a system to notify other stations of its own potentially critical operating state and / or to query the operating state of other stations.

[0088] In favorable use of the described method for guiding a moving object, it should be noted, particularly favorably, that the guiding data that can be determined for various segments is smoothed and / or interpolated at least at the transition points between segments. Advantageously, additional information is referenced, particularly favorably, the intersection of the planned course of the taxiway with the direction angle and / or the odometer value. Here, advantageously, control parameters for the automatic movement of the moving object are determined as guiding data.

[0089] It should be noted that the above-described method for guiding moving objects can also be implemented using, for example, the conventional base station shown in Figure 1. This in itself is considered novel, and similarly, the use with a wobbling planar beam is also considered novel.

[0090] Furthermore, the base station of the present invention or a base station known from the prior art used in the method described above may be configured as a measuring beam transceiver, similar to European Patent Application Publication No. 2998699. This is also considered novel.

[0091] The present invention will be described hereafter merely illustratively, based on the drawings. [Brief explanation of the drawing]

[0092] [Figure 1] This figure shows four different exemplary measuring devices of the prior art, as described in the introduction. [Figure 2] This diagram shows an overview of a favorable measuring device. [Figure 3] This diagram illustrates an advantageous measuring device equipped with an active target, showing the receiving signal of the active target at two different heights. [Figure 4] This figure shows a measuring device with an active remote station having two receivers that are vertically overlapping and spaced at a known interval b, in order to eliminate ambiguity and determine the 3D coordinates relative to the base station. [Figure 5] This diagram shows a measuring device equipped with an active target to which a GNSS antenna is assigned in order to remove ambiguity, where the 3D coordinates of the GNSS antenna can be improved by the active target. [Figure 6] This figure shows a measuring device comprising two base stations with a base spacing b, which remove ambiguity and determine the 3D coordinates of an active target. [Figure 7]This diagram shows six alternative arrangements of optical components at the base station. [Figure 8] This is a cross-sectional view of the optomechanics of a particularly advantageous configuration of the base station. [Figure 9] This is a block diagram of a control circuit with a particularly advantageous configuration for the base station. [Figure 10] This is a block diagram of a particularly advantageous configuration for an active target. [Figure 11] This is an example and description of possible configurations of angle-encoded data signals after reception at an active target in a base station. [Figure 12] This diagram shows the attachment of a laser sensor to construction machinery in a method of guiding construction machinery during road construction (conventional technology, already explained). [Figure 13] This is a top view of the road path using the conventional method, as explained in the introduction. [Figure 14] This figure shows the mounting of an active target in the proposed method for determining the height and attitude of a vehicle. [Figure 15] This figure shows the interpolation in the transition portion between the virtual laser plane and the interpolation point when carrying out the method of the present invention using a virtual guide line or a virtual string line. [Figure 16] This is a top view of the road path and road finisher when implementing the method described in Figure 15, which uses virtual string lines. [Modes for carrying out the invention]

[0093] Figure 2 shows a measuring apparatus, generally referred to as reference number 1, having a base station 2 that emits measurement radiation as a plane. Here, the base station 2 is configured for the wobbling motion of the planar beam 4, which changes the orientation of the normal 6 of the planar beam 4 in a known manner, and a series of orientations of the planar beam normal 6 are performed in a known manner. See phase angle ψ (psi). Furthermore, the measuring apparatus 1 has an active remote station 3, i.e., an active target 3, that receives the measurement beam emitted from the base station 2.

[0094] In the illustrated embodiment, the base station 2 is positioned on a sufficiently stable tripod stand 36 and emits visible light as the radiation to be measured. In the illustrated embodiment, the base station 2 is positioned such that its axis 8 is oriented vertically. Furthermore, as will be explained with reference to Figure 7, in the base station 2, the optical element that deflects the beam rotates around this axis 8. Due to the wobbling motion in the embodiment of Figure 2, the normal 6 to the planar beam 4 is tilted by an angle α (alpha) with respect to the axis 8, and the endpoint of the normal unit vector 6 intersecting the axis 8 circulates around the axis 8 in a circle. The phase angle ψ (psi) indicates the phase of this circular circulation in which this normal vector exists.

[0095] The active target 3 may be fixed to the object to be measured (not shown), for example, in a removable or non-removable manner, or may be held by the object, or may be fixed or movable for positional measurements on the object. It is understood that the swaying planar beam sweeps the active remote station 3, positioned at an appropriate height, twice in each swaying cycle. The active target 3 has a photosensitive element to generate a single characteristic signal each time it receives the measurement radiation generated by the sweep. From the sign of this characteristic signal, symbolized by the curve at the receiver 42 in Figure 2, the orientation of the normal at each time the measurement radiation is received can be inferred, as will be further described below.

[0096] To generate a wobbling planar beam, an optoelectronic beam transmitting element 12 is located within the base station 2 (see Figures 7a to 7f), where optical elements are positioned after the optoelectronic beam transmitting element 12 to shape and invert the beam of the optoelectronic beam transmitting element 12. Numerous optical devices exist that can realize the desired wobbling motion of the planar beam 4. Some of these numerous optical devices are described with reference to Figures 7a to 7f.

[0097] Figure 7a shows a particularly advantageous variant of the optical component arrangement of the base station 2. Here, the optoelectronic beam transmitting element 12 is a laser diode 12 that emits a divergent beam beam. 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 form. This collimated beam is then incident on a rotating beam deflection component 7, which in the illustrated embodiment of Figure 7a is a rotating rectangular prism. The rectangular prism here rotates about a rotation axis 8, which is also parallel to the propagation of the collimated beam beam 11.

[0098] In the embodiment shown in Figure 2, the axis of rotation 8 is vertical, and the wobbling planar beam 4 has a normal vector 6 that is inclined with respect to the vertical axis of rotation 8 by a deflection angle α. To drive the rotation of the rectangular prism, an electric motor 18, simply schematicly shown in Figure 7a, is provided to generate rotational motion.

[0099] Therefore, the collimated beam beam, which is periodically deflected in different directions but always inclined with respect to the vertical line 8 as the rectangular prism rotates, is incident on a 90° conical mirror 5 in the embodiment of Figure 2. This conical mirror 5 converts the deflected and collimated beam beam beam into a planar beam 4, which is further inclined. Here, the inclination of the planar beam 4 is such that the normal 6 to the planar beam 4 is tilted at an angle α with respect to the vertical rotation axis 8, and is located behind the conical mirror 5. As can be seen from Figure 2, the normal 6 periodically circulates around the vertical line 8 in proportion to the rotation of the rectangular prism, and as a result, the planar beam normal 6 repeatedly takes the same orientation while the rectangular prism rotates, and here the current orientation of the planar beam normal 6 is always known as long as it is known how the rectangular prism is currently oriented by the rotation of the rectangular prism caused by the rotary motor 18 around the vertical rotation axis 8. Later, a favorable method is presented for determining how the current orientation of the rectangular prism can be determined by the rotation of the rectangular prism caused by the rotary motor 18 and transmitted to the active target 3.

[0100] The conical mirror 5 expands the deflected and collimated beam bundle to form a planar beam, thus realizing a beam expansion component.

[0101] Note that in the illustrated embodiment, the planar beam has a finite thickness, and this thickness further varies in different directions. This can be seen in Figures 7a and 7b. This effect of the varying thickness is best understood when it is assumed that the tip of the conical mirror 5 is located directly above the vertical axis 8, and further, that the axis of symmetry of the conical mirror passing through the tip of the conical mirror 5 is also located directly above the vertical axis 8. Furthermore, it is assumed that the collimator collimates the radiation from the optoelectronic beam transmitting element 12 into a precisely circular and homogeneous bundle of individual parallel beams. (These assumptions of precise orientation are made solely to better explain the effects of different thicknesses, and the realization of these assumptions is not necessarily required in actual implementation. It should be clearly noted that the present invention or this particular embodiment should never be limited to this assumed precision. Therefore, the precise placement of the conical mirror tip on the vertical axis, the precise coaxial orientation of the conical mirror symmetry axis passing through the tip of the conical mirror 5 with respect to the vertical axis, and, as described above, the precise collimation without divergence and the precisely circular beam bundle are not actually required. The reader should be noted that the respective inaccuracies and deviations are, in some cases, easily tolerable, or can be corrected if higher precision is desired. Nevertheless, it should be mentioned that high structural precision can be achieved in the direction of these simplified assumptions, made for better explanation, without significant effort.)

[0102] Under this simplified assumption of conical mirror orientation, we can particularly understand why the beam thickness varies in different directions. This is done by observing the beam located at the center or outer edge of the collimated beam bundle in each of the two directions: that is, the beam in the direction with the greatest upward planar beam inclination away from the conical mirror 5, or the corresponding beam in the opposite direction with the greatest downward planar beam inclination.

[0103] The central beam of the collimated beam bundle is incident on the conical mirror 5 very close to the tip of the cone. These define the lower limit of the planar beam, both in the direction in which the planar beam rises and in the opposite direction in which the planar beam descends. However, since the collimated beam bundle is inclined with respect to the vertical line 8 and, consequently, the axis of the conical mirror, the outer beams of the beam bundle are directed toward the vertical axis 8 on one side and away from the vertical axis 8 on the opposite side. Accordingly, the outer beams of the collimated beam bundle are incident on the conical mirror 5 at different heights. This can be clearly seen in Figure 7a. Due to this incidence at different heights, after deflection by the conical mirror 5, the thickness of the planar beam differs in different directions. Figure 7b shows that the thickness of the planar beam changes in a direction corresponding to the change in beam inclination. Here, the same arrangement as in Figure 7a is shown in Figure 7b, but in Figure 7b, the orientation of the beam path is additionally indicated by a dashed line relative to the orientation of the square prism which has been rotated 180° further.

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

[0105] However, this effect is precisely calculable and compensable by calculation. Furthermore, the tip of the conical mirror can almost touch the surface of the rectangular prism without beam shadowing of the planar beam, provided that the inclination angle of the planar beam precisely corresponds to the prism angle. This is the case when the material of the rectangular prism has a refractive index of 2.0. In other words, the corresponding imaging error resulting from the changing thickness is not actually critical.

[0106] Figure 7c illustrates that the offset problem of varying the thickness of the planar beam, as described above, is substantially compensable optically and how it is compensated. The optical elements used in this embodiment for beam deflection include, in addition to the similarly used rectangular prism 7, a planar parallel plate positioned between the collimator 10 and the rectangular prism 7 in the beam path and inclined with respect to the axis of the collimated beam. The inclined planar parallel plate is coupled to the rectangular prism 7 so as not to rotate relative to it, and as a result, the inclined planar parallel plate rotates with the rotation of the rectangular prism 7 in Figure 7c. In this embodiment, the beam deflection component also includes an inclined parallel plate in addition to the rectangular prism.

[0107] Figure 7d shows a further embodiment, which differs from the embodiment in Figure 7a in the following respect: In Figure 7d, the parallel, collimated beam is converted into an annular beam, i.e., it has an intensity across the cross-section that is low at the center but higher in intensity away from the center in an annular region. This annular beam profile is obtained by adding two axicons to the collimator. The annular beam profile has advantages with respect to the divergence of the planar beam in the vertical. Therefore, 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 at the base station 2 can be improved using such an annular beam profile.

[0108] In the embodiment shown in Figure 7e, the conical mirror 5 in Figure 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 toward the optical transmitter 12 and a conical recess on the end face opposite the optical transmitter 12. The surface of this plano-concave axicon is optically polished. The beam beam incident on 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 exits from the casing surface. The use of such a plano-concave axicon has advantages in the mechanical configuration of the base station 2 because, unlike a conical mirror, the axicon can be easily held so that a glass tube, glass housing, or completely opaque frame structure does not obstruct or weaken any portion of the beam as it passes through.

[0109] Because of its cylindrical shape, the illustrated axicon can be held coaxially with respect to the axis of rotation, for example, in a suitable tube, with minimal effort, especially below the beam emission region, along with the rotating beam deflection optical element. However, it should be noted that the tip of the conical recess of the axicon cannot be positioned near the emission surface of the beam-deflecting rectangular prism, as in the case of the tip of the conical mirror 5 in Figure 7a. For this reason, when a plano-concave axicon is used instead of the conical mirror 5, two interacting rectangular prisms that deflect the beam with different strengths are used instead of the individual rotating rectangular prisms in Figure 7a, as the deflection by the rotating rectangular prism, which produces different planar beam thicknesses, has a stronger effect. Together, these rectangular prisms ensure that the deflected beam enters the conical surface of the plano-concave axicon at or near the center.

[0110] An embodiment that does not provide particularly high measurement accuracy but enables a particularly small structural size and extremely low cost is shown in Figure 7f. In this embodiment, the beam deflection means is the same as the means for extending the beam into a planar beam. In other words, here the beam deflection component 7 is the same as the planar beam extension component 5. A conical mirror 5 is used here, and its axis of symmetry is tilted by an angle α / 2 with respect to the rotation axis 8 (which is vertical in Figure 2). This is an exceptionally easy solution, but it comes with problems in deflection stability. This is because the dynamic error of the mechanical support of the rotation axis in the usual configuration and the usual tilt angle of the normal of the wobbling surface have an influence that is more than 10 times stronger than in the arrangement in Figure 7a. That is, this variation in Figure 7f is advantageous only when extremely high measurement accuracy is not important, but rather an extremely small structural size and extremely low cost are important, such as in the miniaturization and integration of base stations into smartphones, etc.

[0111] The illustrated optical components enable an advantageous optomechanical construction of base station 2. This is illustrated in Figure 8 as an example, with respect to the mechanical structure of an embodiment that substantially corresponds to the configuration in Figure 7a.

[0112] Figure 8 shows a cross-section of this particularly advantageous variant of the optomechanics of base station 2.

[0113] The optoelectronic beam transmitting element 12 here is a laser diode that emits a divergent beam. The divergent beam is converted into a parallel (infinity) focused beam by a collimator lens 10. As can be seen, the laser diode 12 and the collimator lens 10 are fixedly mounted to each other. They are located inside a hollow shaft 8 that is rotatable around them, and the hollow shaft 8 is fixedly coupled to a rectangular prism 7. More precisely, the rectangular prism is fitted inside the hollow shaft.

[0114] The hollow shaft is rotatably supported by a bearing unit 9 that is pre-tensioned to eliminate play, and is driven by a rotational drive unit implemented 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 magnetic rotor 20 that is coupled to the hollow shaft so as not to rotate relative to it. An encoder disk 21 is simultaneously attached to this rotor, which is scanned by two encoder reading heads 22. The rotation angle of the magnetic rotor can be determined in real time from the signals obtained when scanning the encoder disk 21 using the encoder reading heads 22, and at the same time, the centering error of the encoder disk and bearing runout are compensated for.

[0115] The beam beam, deflected and collimated by the rectangular prism, is incident on the conical mirror 5. As described above, this expands the beam beam into an inclined planar beam, and when the rectangular prism rotates, it causes the desired known wobble of the planar beam. As a result, the encoder reading head 22 can determine the rotation angle of the magnetic rotor in real time from the signal obtained by scanning the encoder disk 21, and at the same time, the rotational orientation of the rectangular prism and, consequently, the phase angle of the planar beam normal 6 in its motion cycle can be determined.

[0116] The base station has a transparent cover 38 on the beam emission side to protect the optical components, which is formed as a glass housing or, advantageously, as a glass tube with closed ends, through which the wobbly planar beam is emitted into the measurement space to be surveyed.

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

[0118] Figure 9 shows a block diagram of the control unit. The control unit has a current supply unit 24 and an interface for calibration and debugging. The control unit further has appropriate encoder electronics and motor electronics 25, through which the control unit is connected to the motor 18 and encoder reading head 22, thereby enabling the central computing unit 33 to determine the motor speed.

[0119] The control unit also advantageously manages not only the user interface 27, but also wireless reading devices 26 for position tags or transponders 37, which may consist of, for example, RFID or NFC technology. These may be located on the stand 36 or attached to the connection point between the stand and the base station (e.g., tripod, tribrush or leveling plate) and correspond to a pre-determined absolute position. The absolute position can be measured, for example, by a stationary GNSS before the survey. Such reference to the absolute position of the base station stand, calibrated by, for example, a stationary GNSS or a tachymeter, makes it possible to realize extensive virtual guidance lines with only a small number of base stations that move in accordance with the progress of the work, when virtual guidance lines are desired. This results in significant cost reductions compared to conventional technology, while also improving user handling.

[0120] It should be noted that the approach of calibrating the base station's installation point to a static absolute position, particularly using a stationary GNSS or tachymeter, and storing this data in a transponder at the base station's stand or installation point, is considered advantageous compared to the prior art and is considered safe in itself. This allows, for example, the construction of a virtual guidance line with base stations that move from one statically calibrated position to the next as construction progresses. The submission of a separate application for this purpose is explicitly reserved. It should be emphasized that such a method is applicable with conventional base stations that do not emit a wobbling planar beam in a defined and controlled manner. Similarly, this method is applicable, in particular, to tachymeters and dual-inclined lasers known from the prior art.

[0121] If the control unit 23 is configured to detect absolute positions, for example, the absolute positions of previously measured position tags, the control unit 23 is advantageously configured to modulate the beams receivable by the active target as follows: that is, they are modulated so that the absolute positions of each base station 2 are transmitted regularly, for example, every few seconds. In this regard, the absolute positions are auxiliary information that is loaded onto the radiation emitted from the base stations for modulation. It should be noted that in some cases, the base stations 2 may be equipped with their own GNSS receivers, which may eliminate the need for prior measurement of the target placement positions relative to the base stations 2.

[0122] The base station 2 further includes a tilt compensator 28 that outputs a tilt instruction signal to the control unit 23, which can also be used for repeated modulation of the emitted radiation.

[0123] In the illustrated advantageous embodiment, the control unit 23 has an interpolation circuit 31, which outputs data words encoding the angular position at positions precisely calibrated to match the encoder. By storing the corresponding correction data in the calibration memory 32, the encoder disk with low linearity can be accurately calibrated, thereby generating highly accurate angular data even with low linearity. The correction data required for this can be easily determined and stored for each encoder disk during manufacturing. It should be noted that the calibration memory may be configured as a non-volatile memory in particular.

[0124] The interpolation circuit 31 converts angle data associated with integer indices, advantageously under fixed angle steps, as well as other auxiliary information, into a data format suitable for radiation modulation, taking into account redundancy and checksums as needed.

[0125] In a variation advantageous for transmitting angle information at a fixed angular position, the angle information is transmitted at fixed time intervals. Thus, the angle given at a fixed point in time may be determined at the base station by interpolation of the angle encoder data and then transmitted as angle information at the next fixed point in time. This has the advantage that the start of a data word can be detected very well at an active remote station, even without a emphasized start pulse. This is also advantageous because it allows for better utilization of available laser power and thus extends the range of the base station.

[0126] Examples of data formats suitable for optical data transmission include the MPPM format or a modified MPPM signal with eight symbols at 128 positions, i.e., optical pulses. This allows for the coding of 40 bits of information per data word. Using a PPM data transmission protocol, i.e., a data protocol other than the MPPM protocol, to modulate the measurement radiation emitted by a base station is considered novel in itself, and this also applies to base stations, rotating lasers, etc., that would otherwise be constructed according to prior art.

[0127] Before describing the data protocol used in more detail, we will briefly mention the structure of the active remote station 3. This makes sense because the data protocol used is advantageously configured to achieve particularly high accuracy with an inexpensive and robust receiver.

[0128] Figure 10 shows a block diagram of an active remote station belonging to the base station 2 described above, namely the active target 3. The active target 3 has a receiving collimator 40, which focuses light onto a light guide 41, and inputs it to the light guide 41, in particular for use with construction machinery. The light guide 41 guides the radiation incident from the base station 2 to a photosensitive optoelectronic element such as a photodiode. The light guide 41 may be a plastic optical fiber (POF), which is several meters long and allows for spatial separation between the radiation incident area on the active target 3 and the optoelectronic and electronic components used for detecting and evaluating radiation reception signs.

[0129] During the sweep of the planar beam across the receiving collimator 40, the light radiation is focused onto the light guide 41 and input to the light guide 41. A receiver 42, which can be implemented as a separate component and reliably mounted inside a machine, for example in construction machinery applications, is thus connected to the outside world only through the light guide 41, which may be several meters long.

[0130] In such a device, the original measurement point is located on a receiving collimator 40, which may be mounted on the outside of the construction machine. This offers significant advantages, particularly in terms of the device's overall sensitivity to vibration and watertightness. The photosensitive optoelectronic element may be fitted with an optical filter to suppress optical interference radiation, typically a bandpass filter 43 having a wavelength transmission range of only a few nanometers wide centered on the emission wavelength of the base station 2. This filter can be placed, for example, in front of the incident lens of the receiving collimator 40, inside the receiving collimator 40, between the receiving collimator 40 and the light guide, or between the light guide and the photosensitive electronic element. However, it is advantageous to place the optical filter as close as possible to the optoelectronic element, because in such cases, a filter with a simply small structural size can typically be used, which offers advantages in terms of price and weight.

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

[0132] The photosensitive optoelectronic receiving element outputs an electrical signal that is supplied to the signal conditioning circuit 48. In this example, a transimpedance amplifier (TIA) with an analog optimization filter is used. The analog output signal obtained after signal conditioning is similarly converted into data for a digital data stream 50 by a high-speed ADC 49. This data stream is supplied to a digital preprocessing and compression circuit 51. This circuit further processes the received data stream digitally. This is done by removing noise and interference signals such as useless signals or interference events due to scattered light from the data stream, thereby supplying the subsequent computing unit with only the data from the data stream that is actually needed for further processing. In other words, such digital data stream processing compresses the data stream.

[0133] Advantageously, such data compression can be performed by particularly inexpensive data processing units, mainly because the same data processing steps can be repeated. Specially constructed units such as FPGAs are well-suited for these steps. The use of data compression is advantageous overall because they allow computing units with low power consumption and relatively low computing power to be used for further processing of the compressed data stream. In this regard, it should be noted that by using an FPGA-based data compressor, the power consumption that would otherwise be required can be reduced to about 1 / 10, which is particularly advantageous when the active target 3 is to be configured as a fully integrated, battery-powered handheld receiver, advantageously without the aforementioned light guide. However, it should be noted that the compressor 51 can be omitted, especially when power consumption plays only a subordinate role and a computing unit with sufficiently high computing power is available.

[0134] It should be noted that it is advantageous for the receiver, i.e., the active target 3, to also be equipped with a communication interface 54, particularly for wireless connectivity via WLAN. This allows it to communicate with other active targets 3 as needed and transfer calculated position information.

[0135] Using the above-described measuring device 1, which has a base station 2 that generates a planar beam that wobbles in a known manner and an active remote station 3, it is possible to determine at what angle with respect to the horizontal line the assumed connection line rises between one active remote station and the other, the two wobble centers of the planar beam located within the base station. This inclination angle will hereafter be referred to as the vertical direction angle. In Figure 2, this is represented by the Greek letter λ (lambda).

[0136] In Figure 2, the position of the active remote station 3 relative to the base station 2 is given in spherical coordinates, and its center point is the center of the planar beam wobble motion. Therefore, in addition to the vertical direction angle, a horizontal direction angle and the distance to the base station 2 are required. It is understood that the direction must be defined at 0° for both the vertical and horizontal direction angles. For the vertical direction angle, a precise horizontal direction with zero inclination is particularly preferable. In contrast, for the horizontal direction angle, the direction itself can be arbitrarily defined. In practice, a direction such as north would be particularly preferable, but here it can be considered sufficient if the horizontal direction angle is related to a direction defined as 0°, to which the phase angle in the motion cycle of the planar beam normal is associated. In this regard, it has already been mentioned that the phase angle in the motion cycle of the planar beam normal corresponds to the rotation angle of the rotary motor driving the square prism, and this rotation angle can be determined by an angle encoder. Without limiting generality, the horizontal direction 0° can be defined using its 0 direction.

[0137] Based on the wobble motion generated as intended by the use of the optical system described above at base station 2, the planar beam normal 6 circulates in a circle as shown in Figure 2. Here, each active remote station 3 is swept twice per circular circulation, i.e., twice per wobble cycle (in any case, as long as the radiation incident surface of the active remote station 3 is between the highest and lowest heights that the planar beam can take). The sweep occurs at a specific phase angle. Given that the two phase angles ψ1 and ψ2 from which the active remote station is swept are known, the horizontal direction angle is initially easily calculated from their average value, i.e., corresponding to (ψ1+ψ2) / 2.

[0138] To determine the vertical direction angle λ (lambda), that is, the assumed upward or downward angle of the connection line between one active remote station and the other, the wobble center of the planar beam located within base station 2, it is also necessary to use the angle at which the normal 6 to the planar beam 4 is inclined with respect to the vertical axis 8. This angle is shown as angle α (alpha) in Figure 2.

[0139] In a given phase angle ψ1 and ψ2, where the active remote station 3 is swept by the wobbling planar beam 4, these variables determine the vertical direction angle λ (lambda),

number

[0140] Figure 3 symbolically illustrates how the change in height of an active target at a given distance from base station 2 affects the interval between sweep events. The change in height is accompanied by a change in the time interval between sweep events, because the planar beam 4 requires different lengths of time, depending on the target height, to wobble further after the first sweep to the orientation in which the second sweep is observed. The duration of different lengths of time clearly corresponds to the rotation of the planar beam normal 6 by different distances simultaneously performing its own motion cycle. However, it is also clear from Figure 3 that the midpoint between the two sweeps is not related to the target height. It should be emphasized that this property corresponds perfectly to and is expressed in the equation described above.

[0141] However, in a simple setup like the one in Figure 2, initially only the repeated sweep sine of the active remote station 3 by the planar beam 4 is detected. Note that it is not clear here whether the observed sine is occurring at a height above the horizontal or below the horizontal (this is affected by the ambiguity of the sign in the above equation).

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

[0143] In Figure 4, the ambiguity is resolved by arranging the two active remote stations 3a and 3b in an overlapping configuration, thereby allowing the height of each active remote station to be uniquely determined 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, and it is also possible to have separate remote stations with two overlapping optical receivers or optical collimators. Thus, a particularly suitable active remote station 3 has more than one individual optical receiver. Particularly advantageous for this setup is that if the vertical spacing b of the overlapping optical receivers is known, the distance 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 distance r of the active remote station 3 to the base station 2.

[0144] Therefore, the 3D position of the active target 3 in the polar coordinate system of the base station can be determined by a receiver device as shown in Figure 4. If an additional receiver is provided, accuracy can be improved by interpolation, and / or if an additional receiver is appropriately placed on the active remote station 3, the orientation of the active remote station 3 in space can also be detected.

[0145] Furthermore, advantageously, the connecting line between the two receivers 3b is allowed to extend at an angle rather than precisely perpendicular to the vertical, without compromising measurement accuracy. Thus, in an advantageous embodiment of the active remote station 3 described with reference to Figure 4, the active remote station 3 is equipped with an inclinometer, and the inclinometer's measurement can be used to compensate for the current inclination.

[0146] As an option and / or additional possibility, Figure 5 shows that ambiguity can be resolved by linking the active target 3 with the 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 improved by referring to the calibrated absolute position of the base station 2 and the position determined relatively here by the active remote station 3. The accuracy of the GNSS position can be significantly improved, especially with respect to height measurement. This device is particularly advantageous when a highly accurate absolute position is absolutely required.

[0147] Figure 6 shows a further apparatus capable of automatically resolving ambiguity. Here, two base stations 2a and 2b are installed at a known base spacing b and are calibrated relative to each other with respect to their horizontal axes. For an active target 3 located in the measurement space of both base stations, i.e., capable of receiving radiation from both stations for measurement purposes, the 3D position of the active target 3 can be determined by 3D triangulation.

[0148] The following implementation is particularly advantageous, namely, that passive targets 34a and 34b are mounted on each of the two base stations 2 used, advantageously aligned with the rotation axis of the other station, in which case the base stations themselves are also configured for radiation reception as described above, and are configured to measure the lateral distance between the two base stations by determining the pulse propagation time from the first base station to the reflected passive target of the second base station and back, in addition to the horizontal and vertical angles.

[0149] This configuration has the advantage that the station can be automatically calibrated during installation, and the acquired information about each adjacent station can be transmitted to the active remote station 3 via radiation modulation, along with the supplementary information. In this case, there is no need to initiate a calibration process, nor is there a need to query the results of the calibration process via a wireless interface. Here, the installation process is as simple as that of a total station.

[0150] As far as height determination is concerned, it would essentially suffice in all variations to determine the sweep time and then assume the parallel rotation speed of the square prism. However, as soon as variations in parallelism occur, this not only limits accuracy but also makes it impossible to completely determine all coordinates of the active remote station 3. Therefore, the above explanation assumes that the actual rotation angle of the square prism rotation or the phase angle in the motion cycle of the planar beam normal itself is known.

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

[0152] Referring to Figure 11, the following details of a data protocol particularly suitable for modulating an optoelectronic beam transmitting element, in this case, a laser diode 12.

[0153] It should first be remembered that the wobbling planar beam 4, although it may change in different directions as shown above, always has a regularly finite thickness. Therefore, when the receiver is swept, a finite amount of time elapses from the time the first beam enters the receiver until the last beam leaves the receiver. On the one hand, this beam reception time is sufficient to receive encoded information. On the other hand, the wobbling planar beam continues to move during this time; that is, the phase angle of the planar beam normal 6 changes during the sweep.

[0154] On the one hand, this can be used for receiving a series of time-encoded data, and on the other hand, it can be taken into consideration to improve the accuracy of the measurements.

[0155] Advantageously, for this purpose, information concerning the current rotational angle orientation of the rotating rectangular prism, and consequently the current phases in the motion cycle of the planar beam normal, is transmitted from the base station 2 to the active remote stations 3 or each active remote station 3. A suitable protocol for data that can be loaded onto the radiation emitted from the base for modulation is described with reference to Figure 11.

[0156] Furthermore, Figures 11a to 11c show the temporal evolution of the radiation power of the radiation emitted from the base station, characterized by the information loaded for modulation.

[0157] Next, in the illustrated advantageous implementation, a 40-bit wide data word 15 is used, each consisting of a start symbol for synchronization and eight subsequent data symbols, which are easily identifiable by the receiver. Each symbol is typically realized by a needle-like pulse.

[0158] The desired information is encoded by the temporal positions of eight needle-like pulses that follow each start symbol, corresponding to the data symbol, before a new start symbol is generated. In the illustrated embodiment, each of the eight needle-like pulses lies on one of 128 codeable temporal positions. As shown in Figure 11c, this results in a temporal change in the modulation pattern corresponding to the data to be transmitted. The start symbol is particularly easy to identify because it is different from the data symbol. There are various techniques for doing this. In Figure 11a, the start symbol uses a pulse that is stronger than the pulse of the data symbol. Such coding is called bilevel coding. In Figure 11b, instead, a double pulse is used, which is constructed from two needle-like pulses that are very close in time to each other. The time interval between the very close pulse peaks of the double pulse is so short that it does not appear in the rest of the data word. That is, the time interval of the double peak is shorter than the shortest interval of the 128 codeable temporal positions.

[0159] It should be noted that the start symbol is not used solely to identify a new data word. Rather, synchronization can also be estimated from the temporal sequence of start symbol pulses, that is, the active remote station 3 can determine how long base station 2 needs to transmit a complete data word, and from this, it is possible to estimate how long the time intervals between the 128 protocol-encoded time positions will last. This synchronization can be performed, for example, under automatic correlation to the time intervals between start symbol pulses, provided that the active remote station 3 has sufficient computing power.

[0160] Furthermore, to better utilize the radiative capability of the beam transmitting element and, consequently, to extend the resulting range, it may be advantageous for the start symbol not to be bilevel encoded, i.e., not transmitted with an amplitude distinguishable from the data pulse, and furthermore, for double pulse transmission not to occur at the start of a data word. In fact, a specific start pulse could even be omitted entirely. In such cases, for example, brute-force decoding using checksums, or soft decoding or autocorrelation using fixed time intervals between data words can be used for synchronization.

[0161] Figure 11c shows a sequence of multiple different angle-encoded data words 15, each of which represents the rotational angle position ψ detected at the time of the start pulse. n-1 ~ψ n+2 Encode it.

[0162] The data protocol enables sufficiently rapid and interference-free data transmission through modulation of the transmitted radiation. In actual embodiments, for example, it was possible to transmit the data word 15 described above within 2.5 μs. This makes it possible to transmit current rotation angle information or auxiliary information sufficiently frequently.

[0163] It should be noted that the described transmission method effectively eliminates latency issues in transmission between the base station and the active remote station. While there may be a time delay between the detection of a specific rotational angle position by the angle decoder at base station 2 and the imprinting of corresponding information onto the transmitted radiation for modulation, this latency occurs within the base station and, with good approximation, is remarkably constant over time, i.e., ignoring the effects of temperature (although these effects can be reduced by temperature control). In this respect, this transmission differs from current angle information communication via other communication paths such as WiFi, where latency can fluctuate significantly. Therefore, the described data transmission is particularly advantageous, and this also applies to conventional base stations with stable planar beams.

[0164] In the implementation described above, so-called pulse position modulation (PPM) is applied. In addition to such PPM modulation, it should be disclosed that other modulation methods, such as those known from the prior art, are applicable. In particular, the usefulness of Manchester coding and PSK, QPSK, and QAM modulation methods is explicitly disclosed without limitation.

[0165] Here, the measurement accuracy is improved by transmitting angle encoder data using the modulation described. As mentioned above, in the active remote station 3, it takes a certain amount of time for the receiver to be completely swept by the wobbling planar beam. This is because the planar beam has a finite thickness, and the receiver has a finite extent. During this duration, the orientation of the wobbling planar beam also changes. Therefore, it is proposed to improve the measurement accuracy by determining the temporal centroid of the sweep interval and interpolating the angle information obtained during the sweep interval by the modulated received radiation relative to this temporal centroid.

[0166] Note that the power received by the receiver of the active remote station 3 changes during the sweep. This is easily explained by the fact that the planar beam is incident on the entire surface of the receiver only for a portion of the sweep interval, while the planar beam is not incident on a portion of the receiver at the beginning and end of the sweep. This action results in an envelope curve 47 that changes the received power, as shown as an example in Figure 11d.

[0167] To interpolate angular information, that is, to accurately determine the phase angle in the motion cycle of the planar beam normal, it is first necessary to determine the temporal centroid of this envelope curve. Next, the associated angles are determined by interpolation with respect to this temporal centroid.

[0168] However, the envelope curve itself is not readily available. However, since it is sufficient to consider only the height of the pulse peak deformed by this curve, the envelope curve is not absolutely necessary. That is, in this respect, the analog shape 46 of the data stream deformed by the envelope curve is taken up again. A reasonable and low receive power threshold is defined, and if it is above or below such a threshold, the start time t start and stop time t end This can be done particularly easily once these are determined. See Figure 11d.

[0169] Therefore, a reasonable boundary t start and t end If you wish to determine the temporal centroid between [time interval], you can use the following equation as a discrete approximation.

number

[0170] The value of the temporal centroid obtained in this way is slightly related to the data content of the data word, since the data content of the data word is encoded via the time position of the needle-shaped pulse, but nevertheless still enables the determination of the temporal centroid to be carried out very well.

[0171] In FIG. 11d, the temporal centroid is t c as shown. This temporal centroid is located between the time points t n and t n+1 at which the start pulse indicating the start of transmission of the data word is received, and these are determined immediately before or after the time t c and encode two rotational angles or phase angles ψ n or ψ n+1 to be transmitted.

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

Equation

[0173] Next, using this rotational angle, the direction angle can be calculated according to the above formula.

[0174] This method can be used to interpolate between the angle steps encoded by the transmitted data word much better than 1 / 10 of the angle step interval. Typically, in this way, an accuracy better than 2 seconds of arc can be obtained. For example, in an actual embodiment of base station 2 where a wobbling planar beam spreads with an opening angle α (alpha) of ±5°, a vertical angular resolution of 0.17 seconds of arc was obtained.

[0175] The high accuracy and the simple and thus inexpensive mechanical structure enable the use of the disclosed measurement system, particularly in applications such as road construction, and / or for the definition of virtual guidance lines.

[0176] Figure 14 shows, in contrast, that the active target 3 is mounted on the kinematic centers of the rolling elements 69 of the road roller and the screed 70 of the road finisher. The screed is used to level the hot asphalt pavement 68 to a predetermined height. This predetermined height should be set by a virtual guide line.

[0177] The measurement system disclosed above makes it possible to determine the so-called slump when a road roller repeatedly runs over still-hot pavement, based on the high accuracy obtained; that is, it makes it possible to indicate how strongly the road pavement is compacted by running over it. This also makes it possible to directly display the degree of compaction of the road pavement to the machine operator. A corresponding output means is provided in an active remote station. Advantageously, at least two active targets or active remote stations having two receiving points, which enable the determination of absolute height, as illustrated, are attached to the screed.

[0178] Figure 15 shows how a virtual string line 64, with two base stations 2a and 2b and a stationary target Rx, can be provided spanning between them. Here, two virtual planes 65a and 65b are determined for base station 2a, and two virtual planes 65c and 65d are determined for base station 2b. Here, virtual planes 65b and 65c include the respective connection lines of base station 2a or 2b to the stationary target Rx, which are positioned between them. In order that virtual planes 65b and 65c are fully defined, a desired orientation can be further defined perpendicular to the connection lines. That is, a desired lateral inclination of the virtual planes connecting the multiple base stations and the target between them is defined. Here, based on these virtual planes, an interpolated plane or a virtual guide line can be defined. Thus, the stationary active target 3, i.e., the stationary active remote station 3, can provide interpolation points for the interpolated plane or guide line. This is significantly easier to construct and therefore less expensive than a base station, even when using a base station according to the present invention with a wobbly planar beam.

[0179] Figure 16 shows a top view of a road construction 67 equipped with a road finisher 61 and an active target 3 attached to its screed, illustrating that a virtual guidance line 64 constructed according to the present invention, using an active remote station Rx as an interpolation point, can be used for height determination and attitude determination, and how it can be used. It should be noted that when additional information such as intersections of direction angles is mixed with the planned course of vehicle travel, or when odometer values ​​are calculated by subtracting this information, the determination of a freely selectable absolute position can be omitted, at least for height control. Nevertheless, the control parameters necessary for interpolating and smoothing the guidance variables at segment transitions can be determined with sufficient accuracy.

[0180] While the measuring device of the present invention is applicable to the guidance of vehicles and machinery, and the methods of application thereof have been clearly described above, it should be emphasized that this measuring device also offers advantages to many other applications.

[0181] For example, this measuring device can be used as a replacement for dual-slope lasers operating on construction sites. A particular advantage here is that it allows for setting the inclination of the virtual laser plane on the active target and arbitrary setting of the inclination axis on the active target.

[0182] Furthermore, it is conceivable that different users would be working on different tendencies here. Also, for example, it could be applied to leveling conical surfaces of conical deposits of material, which would otherwise require expensive specialized lasers.

[0183] It should be noted that, as with multi-cross lasers, it is possible to project multiple virtual planes standing perpendicular to each other without mechanically rotating the base station, and to orient them with an active target. These characteristics are extremely advantageous for industrial surveying when orienting the machine and shaft.

[0184] This measuring device can be used, more advantageously, for controlling the internal attitude of segments in tunnel boring machines, as a central component of innovative waterway construction lasers, and for deformation measurement in monitoring applications.

[0185] Accordingly, in particular, a measuring device for position determination is described, which comprises at least one object whose position or orientation is to be determined, at least one active target spatially fixedly associated with this object, and at least one base station in which the active target is located within its detection range, wherein the base station generates a wobbling planar beam, the normal of the planar beam rotates about a rotation axis at a rotation angle that is always known, and the wobbling motion is defined by the planar beam being incident on the active target at least twice for each rotation of the normal. This rotation axis is perpendicular to the normal of the planar beam at a predetermined, substantially constant inclination angle, and is not parallel to the normal of the planar beam.

[0186] A corresponding measurement setup is also disclosed, in which at least two angular positions of the rotation of the normal of the planar beam around the rotation axis 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] Furthermore, a corresponding measuring device is disclosed in which an active target is configured to calculate at least one vertical angle with respect to the polar coordinate system of the base station.

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

[0189] Furthermore, a corresponding measuring device is disclosed in which the base station includes a rotating beam deflection component.

[0190] Furthermore, a corresponding measuring device is disclosed in which the base station includes a planar beam expansion component.

[0191] Furthermore, a corresponding measuring device is disclosed in which the base station includes an optoelectronic beam transmitting element, the radiation from the optoelectronic beam transmitting element is collimated, deflected by a rotating beam deflection component, and expanded by a planar beam expansion component to form a wobbling planar beam.

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

[0193] Furthermore, a corresponding measuring device is disclosed that transmits additional auxiliary data in addition to angle data.

[0194] Furthermore, a corresponding measuring device is disclosed in which the transmitted auxiliary data includes the attitude of the tilt compensator in the base station.

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

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

[0197] A method for determining the height and attitude of a vehicle by an optical or quasi-optical positioning device is also described, which includes at least one active target fixedly associated with the vehicle, and at least one base station in which the active target is located within its detection range, and at least one other fixed active target, wherein a connecting line between the base station and the fixed active target spans a segment of a virtual guide wire and a virtual plane having a predetermined lateral inclination, on which the vehicle is guided at its working height using the directional angle of the base station obtained by the active target, similar to a conventional guide wire.

[0198] Advantageously, to determine the height and attitude of the vehicle, in such a method, multiple alternating segments consisting of base stations and mounted active targets form a chain of segments of virtual guidance wire.

[0199] Furthermore, it should be noted that, to determine the control parameters necessary for interpolating and smoothing the inductive variables at segment transitions, additional information such as intersections of directional angles may be mixed with the planned course of the vehicle's travel, or the odometer may be subtracted from the calculation.

[0200] It should be noted that in many places, a base station that generates a wobbling planar beam has been mentioned, where the wobbling motion is defined by the normal of the planar beam rotating at a known rotation angle about a rotation axis, and the planar beam being incident on an active target at least twice for each rotation of the normal. This rotation axis is perpendicular to the normal of the planar beam at a predetermined, substantially constant inclination angle, not parallel to the normal of the planar beam. Such wobbling motion generated by the rotation of the normal to the planar beam is particularly advantageous because, as is evident from the above description, it is easily generated and detected. However, it should be noted that other motions are possible in some cases. This is achieved, for example, by superimposing more complex motions on optical elements used for beam tilting, such as a conical mirror or a plano-concave axicon, rather than simply rotating about an axis parallel to the axis of the incident beam. For example, as mentioned above, the rotation of the normal can be combined with an additional tilt caused by an actuator. In that respect, the precession of a gyroscope, which similarly does not need to be perfectly regular, should be recalled.

[0201] However, it should be emphasized that certain information can also be transmitted in other ways, for example, wirelessly or via wired connections. However, when angular information is transmitted, it is advantageous that the latency is precisely known.

Claims

1. An angle synchronization method, A base station that emits radiation and an active receiver having a finite extent and equipped with a photosensitive element for receiving the radiation emitted from the base station are synchronized with each other. The base station emits the radiation as a rotating beam, as a wobbling planar beam or a rotating planar beam, or as a rotating planar beam or fan. The angular position of the rotation is determined by an angular encoder that encodes the relevant angular position of the beam deflection component in discrete angular steps. A data signal encoding the angular position of the beam deflection component is superimposed on the emitted radiation for modulation. Each beam reception event in which the photosensitive element receives the emitted radiation during the rotation continues over the sweep interval. moreover a) By interpolating the discrete angular steps encoded by modulating the radiation received during the sweep interval, and / or b) By referring to the temporal centroid of beam reception during a single sweep interval, The current angular position is determined with subsampling accuracy via the active receiver during the sweep interval. Angle synchronization method.

2. The modulated beam is modulated such that the beam has pulse peaks. In the receiver, the envelope shape is determined based on the height of the pulse peak. after that The temporal centroid of the aforementioned envelope shape is determined. The angle synchronization method according to claim 1.

3. A receiving power threshold is defined, and the system starts at a time t when the receiving power threshold is exceeded or fallen below it. ｓｔａｒｔ Or stop time t ｅｎｄ Interpreted as, The temporal centroid between the start time and the stop time is determined. The angle synchronization method according to claim 2.

4. The aforementioned temporal centroid [Math 1] It was decided as follows: t ｓｔａｒｔ Or t ｅｎｄ This indicates the start time or stop time. p(t) represents the elapsed time of the envelope curve p(t). The angle synchronization method according to claim 3.

5. In determining the temporal centroid, the data content relationship of the envelope curve is ignored in order to interpolate the subsampling accuracy. The angle synchronization method according to claim 4.

6. The interpolated angle ψc is obtained from the rotation angle ψn or ψn+1 encoded in time tn, tn+1, at the temporal centroid tc. [Math 2] Determined according to The angle synchronization method according to claim 1.

7. The receiver is swept over a certain period of time when the beam is received. The temporal centroid of the beam reception is determined, The aforementioned temporal centroid [Math 3] By determining this, interpolation is performed with respect to the aforementioned temporal centroid, t ｓｔａｒｔ Or t ｅｎｄ This indicates the start time or stop time. p(t) represents the elapsed time of the envelope curve p(t), The interpolated angle ψc is obtained from the rotation angle ψn or ψn+1 encoded in time tn, tn+1, at the temporal centroid tc. [Math 4] Determined according to The angle synchronization method according to claim 1.

8. The modulated beam is modulated such that the beam has pulse peaks. In the receiver, the envelope shape is determined based on the height of the pulse peak. The angle synchronization method according to claim 7.

9. In determining the temporal centroid, the data content relationship of the envelope curve is ignored in order to interpolate the subsampling accuracy. The angle synchronization method according to claim 8.

10. The distance between the base station and the photosensitive element is large. The beam reception event contains a significant amount of noise. and / or short, when the receiving end can only decode one angular step, The subsampling accuracy interpolation is performed by taking into account the envelope curve and the rate of change in angular position of the received signal. The angle synchronization method according to claim 1.

11. A receiver for implementing the angle synchronization method described in claim 1, The receiver is formed as an active receiver equipped with a photosensitive element, To demodulate a data signal that encodes the current angular position of the beam deflection component of the base station in discrete angular steps, which is loaded onto the received radiation for modulation, The system is configured to interpolate the receiver's coordinates with subsampling accuracy by interpolating between the coded discrete angular steps. Receiver.

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