AT519953B1 - Modular laser scanning system - Google Patents

Abstract

Modular laser scanning system (1) comprising a housing (2) with a laser receiver beam transceiver (9) (6), a first scan head (3) with a first beam deflector (18, 23) and a second scan head (4) with a second scan Beam deflection device (37, 41), wherein the first and the second scan head (3, 4) by means of a coupling device (24; 25, 26) are modularly interchangeable with each other on the housing (2) anchored.

Description

Description [0001] The present invention relates to a modular laser scanning system for scanning an environment.

Laser scanner for environmental detection are needed in a variety of scenarios, be it terrestrial for scanning buildings, streets, mines, etc., airborne for surveying landscapes of aircraft, or at sea for surveying the seabed, coastlines or the like , A laser measuring beam is scanned across the area to be measured by a beam deflecting device, and distance measuring points and a sampling point cloud (a "3D model") of the surroundings in one are determined by transit time measurements of the laser reflected laser beam received back from the laser scanner Coordinate system created. Different surveying tasks require different laser scanners, which have different types of scanners, for example circular (360 °), fan-shaped, fan-shaped, fan-shaped, etc. Thus, in some applications, such as scanning tunnels, gullies, etc., there is a 360 ° scan fan while in other applications, such as airborne landscape scanning, a down-beam circular sector or cone-shaped sector-shaped scan fan is beneficial to avoid unnecessary laser firing into the air.

The invention has for its object to provide a laser scanning system, which can cover different application scenarios in a simple manner.

This object is achieved according to the invention with a laser scanning system, which is characterized by the combination of a housing with a transceiver for a laser measuring beam and a first window for the passage of the laser measuring beam, a first scan head on one side with the first window alignable second window for the passage of the laser measuring beam and behind a first motor-driven beam deflecting device, by means of which the laser measuring beam to a first aperture on another side of the first scan head passing through the first scan fan can be fanned, and a second scan head, on one side with a the first window alignable third window for the passage of the laser measuring beam and behind a second motor-driven beam deflection device, by means of which the laser measuring beam to a second aperture on another side of the second scan head passing through, from the first Sc can be fan-out different second scanning fan, the first and the second scan head by means of a coupling device are mutually exchangeable modularly anchored to the housing, so that in the anchoring position, the first window is aligned with the second or third window.

The invention thus provides a modular system for a laser scanner, in which a base housing can be combined with the entire optoelectronics for sending and receiving the laser measuring beam with different scan heads for the generation of different scan compartments. By simply exchanging one scan head for another, a different scan fan can be selected, for example a cone-shaped scan fan instead of a circular disk or sector-shaped scan fan.

It is particularly favorable when the first beam deflecting device comprises a motor-driven rotatable or oscillatable deflecting mirror and the second beam deflecting device contains a motor-driven rotatable or oscillatable optically refracting element. As a result, completely different types of scan compartments can be generated with one and the same laser scanning system.

For example, the first beam deflection device is preferably a rotatable deflection mirror and the first aperture is a 360 ° round window in order to generate a circular disk-shaped scanning fan with the first scan head, which is particularly suitable for terrestrial scanning tasks. Advantageously, in this embodiment, the drive motor of the deflecting

Mirror on the side facing away from the second window of the first scan head to allow unimpeded coupling of the laser measuring beam from the second window to the deflection mirror.

Such a scan head can preferably be exchanged for a second scan head, wherein the second beam deflection device is a rotatable wedge disc made of transparent material. As a result of the optical refraction effect of the wedge disk during the passage of the laser measuring beam, the latter, as it rotates, fans out the laser measuring beam to form a cone-shaped scanning fan, which is particularly useful in airborne or sea-based laser scanning.

In this variant of scanning head, the drive motor of the wedge disk is preferably a ring motor with an external stator and an internal annular rotor which surrounds the wedge disk. This combines pivot bearing and drive the wedge disk in a very compact, space-saving manner. Alternatively, the wedge disk can be supported by at least three rollers distributed over its circumference, of which at least one roller is motor-driven, which enables a particularly low-friction bearing for high rotational speeds.

In a further embodiment, in the second scan head between the third window and the wedge disk, a 90 ° -Umlenkspiegel be arranged to account for different installation situations can. However, it is particularly advantageous if this deflection is designed as a separate detachable module of the laser scanning system, i. the laser scanning system comprises an angle module which contains a deflecting mirror, preferably a 90 ° deflecting mirror, for the laser measuring beam and can be coupled by means of complementary coupling elements into the coupling device between the housing and the first or second laser head. Of course, angle modules can be created with other deflection angles, for example, 15 °, 30 °, 45 °, 60 ° or 75 °, depending on the application.

The coupling device for connecting the housing, scanning heads and angle modules is preferably a quick coupling, for example with clamping locks, and particularly preferably a bayonet coupling, which is arranged in an annular manner around said aligned one another windows.

According to a further preferred feature of the invention, the housing, the scan heads and the optional angle module each have electrical contacts over which in the anchoring position of the drive motor of the respective scan head is powered by a supply circuit of the housing ago. This allows a quick change of scan heads, without having to make separate cable connections. For the same reasons, it is particularly advantageous if in the case that each beam deflection device is equipped with an angle encoder for its deflection angle, this angle encoder is connected in the anchoring position via further electrical contacts of the housing and the respective scan head to an evaluation circuit of the housing.

The angular range in which the beam deflector of the respective scan head operates is of its type - e.g. with one or more deflecting mirrors or with a visually refracting wedge disk - as well as any deflection mirrors present therein. In order to enable automatic adaptation of the evaluation circuit in the housing to different scan heads and / or angle modules, preferably the scan heads - and optionally the angle module, if present - each have a data carrier with a unique identifier of the scan head, and the housing is provided with a reading device for equipped the disk. The data carrier can be an optical data carrier, for example a barcode which is read by an optical reading device, or a memory chip which is read out via further electrical contacts, or preferably a radio-readable data carrier, for example a RFID tag (Radio Frequency Identification Tag), in which case the reading device works wirelessly.

The invention will be explained in more detail with reference to examples shown in the accompanying drawings. In the figures: Figures 1 to 5 show the laser scanning system of the invention respectively in the anchoring position of different components of the system in perspective views (Figures 1 and 2) and schematic sectional views (Figures 3 to 5). Fig. 6 shows the coupling device of the laser scanning system of Figures 1 to 5 in a schematic end view of a part of the two-piece coupling device. and FIG. 7 shows an alternative mounting of the wedge disk of the second scan head of FIG

Fig. 2, 4 and 5 in a schematic plan view.

In the embodiment of FIGS. 1 to 5, a laser scanning system 1 with four system components 2 - 5 is shown, which can be combined modularly different from each other to each create a laser scanning system 1 with different properties for a different application.

All possible combinations of the laser scanning system 1 in common is a base module in the form of e.g. approximately parallelepiped or cylindrical housing 2, which contains the electronic and electro-optical components for the transmission, return and processing of a laser measuring beam 6. By measuring transit times at the laser scanning system 1 emitted, reflected at a point P of an environment to be measured 7 and returned again in the laser scanning system 1 laser measuring beam 6 can be measured in a conventional manner, the distance of the laser scanning system 1 to the point P; and from a plurality of such measured points P can then - knowing the position and spatial position of the laser scanning system 1 and in knowledge of the current emission and reception direction of the laser measuring beam 6 - in a coordinate system 8, a 3D model of the environment 7 in the form of a "point cloud Of sample points P as known in the art.

For this purpose, the housing 2 includes a transceiver 9 for the laser measuring beam 6. The transceiver 9 is disposed behind a window 10 which lies on one side of the housing 2. The transceiver 9 comprises, on the one hand, a laser diode 11 and a deflecting mirror 12 for emitting the laser measuring beam 6 and on the other hand a converging lens 13 and an optical receiver 14, e.g. Due to the mostly diffuse reflection of the laser measuring beam 6 at the environment 7 this is usually expanded expanded and focused by the converging lens 13 on the receiver 14. With 15 an attached to the transceiver 9 evaluation circuit is referred to, which may be arranged in the housing 2, which is not mandatory. 16 denotes a supply circuit arranged inside or outside of the housing 2 for supplying power to the components of the laser scanning system 1.

The housing 2 is modular with different scan heads 3, 4 for beam deflection or fanning (for "scanning") of the laser measuring beam 6 via the environment 7 can be coupled. Two different embodiments of scan heads 3, 4 are shown in Figs. 1 and 3 on the one hand and Figs. 2, 4 and 5 on the other. In each case, an optional angle module 5, which performs an angular deflection of the laser measuring beam 6, can be interposed between a scan head 3, 4 and the housing 2. For example, FIGS. 2 and 4 show a 90 ° angle module between housing 2 and scan head 4.

The first type of scan head 3 will be explained in more detail with reference to FIG. The scan head 3 contains mainly a rotating about an axis 17, inclined at 45 ° to the axis 17 deflecting mirror 18. The deflecting mirror 18 is disposed on the one hand behind a window 19 of the scan head 3, which is aligned with the window 10 of the housing 2 to from there receive the laser measuring beam 6 and return the ambient reflected laser measuring beam 6 there again, and on the other hand surrounded by a 360 ° all-round window 20, which is also referred to here as "aperture" 20 of the scan head 3. The window or the aperture 20 is, for example, a glass tube of any cross-section housing parts 21, 22 of the scan head 3 between two Ge, one housing part 21 containing the window 19 and the other housing part 22 a drive motor 23 for the rotary drive of the deflecting mirror 18 ,

Upon rotation of the deflecting mirror 18, the laser measuring beam 6 is fanned both in its Sendeais and its receiving direction to the aperture 20 passing through, normal to the axis 17, approximately circular disc-shaped scan compartments 6 '. When the laser scanning system 1 in the configuration of Figs. along the axis 17 of a vehicle, such as land vehicle or aircraft, is moved, can be created with such a circular disk-shaped scan compartments 6 ', a 3D model of the environment 7.

The scan head 3 of FIGS. 1 and 3 is modularly interchangeable anchored to the housing 2, by means of a coupling device 24, which in the anchoring position shown in Figs. 1 and 3, the window 19 of the scan head 3 with the window 10 of Align housing 2. It is understood that the windows 10, 19 are both open, i.e., open. simple openings, as well as may be closed, i. sealed with a transparent to the wavelength of the laser measuring beam 6 material to seal the interior of the housing 2 and scan head 3 against ingress of dust and dirt.

The coupling device 24 can be of any type known in the art, for example in the form of snap closures or latching hooks, by means of which the scan head 3 can be anchored to the housing 2. The coupling device 24 is preferably a bayonet coupling with a first bayonet ring 25 arranged on the housing 2 around the window 10 and a second complementary bayonet ring 26 arranged on the scan head 3 around the window 19. FIG. 6 shows an end view of a simple embodiment of FIG such bayonet rings 25 - the other bayonet ring 26 is complementary thereto - with one or more bayonet grooves 27, into which a complementary bayonet head 28 in the axial direction and can be locked by mutually rotating the bayonet rings 25, 26 therein, as known in the art.

Of course, all the bayonet grooves 27 may be arranged on the one bayonet ring 25 and all bayonet heads 28 on the other bayonet ring 26. All other types of bayonet couplings are possible, such as circumferential projections on a flange, which engage in corresponding bayonet grooves on the inside of a counter-flange, etc.

The coupling device 24 may be the same equipped with electrical contacts 29, 30, which are closed when closing the coupling device 24 - here: in the mutual investment and bayonet lock the bayonet rings 25, 26 - to electrical connections between the housing 2 and the Scan head 3 produce. For example, the drive motor 23 of the scan head 3 can be supplied with power from the feed circuit 16 of the housing 2 via the electrical contacts 29. Furthermore, via the electrical contacts 30, a connection between an angle encoder 31, the respective current deflection angle of the deflection mirror 18, e.g. the rotational position of the deflecting mirror 18 about the axis 17, encoded, and the evaluation circuit 15 are produced. From the respective deflection angle measured value in conjunction with corresponding measured values of the position and spatial position of the laser scanning system 1 in the coordinate system 8 and the corresponding distance measurement values of the points P, the evaluation circuit 15 or a downstream circuit can locate the points P correctly in the coordinate system 8 and from this the 3D Create model of environment 7.

2, 4 and 5 show another embodiment of a scan head in the form of the scan head 4, which - modular exchanged against the scan head 3 - is anchored to the housing 2, once with the interposition of the angle module 5 (Fig and 4) and once directly (Fig. 5). The scan head 4 has the same coupling part of the coupling device 24 as the scan head 3, for example a bayonet ring 26, while the housing 2 carries the other bayonet ring 25. In the case of the interposition of the angle module 5 in the coupling device 24 and the angle module 5 has corresponding complementary hitch be parts for the coupling means 24, e.g. on one side a bayonet ring 25 for coupling with the bayonet ring 26 of the scan head 4 and on the other side a bayonet ring 26 for coupling with the bayonet ring 25 of the housing second

The optional angle module 5 essentially comprises a deflection mirror 32, the laser measuring beam 6 between an alignable with window 10 of the housing 2 window 33 of the angle module 5 and one with a window 34 of the scan head 4 alignable window 35 on another side of the Angle module 5 um (here :) 90 ° deflects. However, the deflection may also be by an angle other than 90 °, e.g. by 15 °, 30 °, 45 °, 60 °, 75 °, etc., and several angle modules 5 could be connected in series to accommodate different installation situations.

The scan head 4 contains a different type of beam deflecting device than the scan head 3, on the basis of an optically refractive element, here a mounted in a sleeve 36 wedge disk 37 made of a transparent to the wavelength of the laser measuring beam 6 material, the passage of the Knife blade 6 optically refracts them to the air at the interfaces 37 ', 37 "of the wedge disk 37. The two boundary surfaces, ie disk sides 37', 37" of the wedge disk 37 are non-parallel, and by rotating the wedge disk 37 about its axis 38, the laser measuring beam 6 passing through it is fanned out in both the transmitting and the receiving direction to form a cone-shaped scanning fan 6 ", which passes through an aperture 39 of the scanning head 4. The aperture 39 can again be open or closed, such as the aperture 20. During the scan fan 6 'of the scan head 3 of FIGS. 1 and 3 when hitting a planar environment 7, a straight scan line of dots n P, the scanning fan 6 "of the scanning head 4 of Figs. 2, 4 and 5, when hitting a planar environment 7, provides a conic-shaped, e.g. circular scanning line 40 of points P. When the laser scanning system 1 in the configuration of Figs. 2, 5 and 5 is driven, for example, by a vehicle, e.g. an aircraft, is moved normal to the axis 38, from a family of successive sampling 40 again a 3D model of the flown environment 7 can be created.

The wedge disk 37 is driven in the embodiment of FIGS. 4 and 5 by a ring motor 41 in the scan head 4 for rotation about the axis 38. The wedge disk 37 is either directly in the ring motor 41 or e.g. mounted on the sleeve 36 in bearings 42 of the scan head 4.

The ring motor 41 comprises an outer, mounted in the scan head 4 annular stator 43 and an inner annular rotor 44, which surrounds the wedge disk 37 and its sleeve 36 and holds.

Fig. 7 shows an alternative way of supporting the wedge disk 37 for particularly low friction and high rotational speed. The wedge disk 37 is mounted here by at least three rollers 45 distributed over its circumference, of which at least one is motor-driven.

It is understood that the laser scanning system 1 can be extended by more scanheads 3, 4 and / or angle modules 5, for example scan heads with other types of beam deflection devices. Thus, instead of the rotating mirror 18 of the scan head 4, a mirror 18 oscillating around an angular range can also be used, so that the aperture 20 also needs to be opened only over a limited angular sector. Also, instead of a single deflecting mirror 18, entire deflecting mirror systems may be used, for example rotating mirror wheels with mirror facets, mirror prisms, etc. Also, a combination of multiple mirrors rotating or oscillating about different axes is possible to provide a scan head which scans the laser measuring beam 6 over a solid angle range scanning leads, ie not merely a flat, but a solid angle scan 6 'generated. Instead of a wedge disk 37, e.g. a plurality of separately rotatable, from the laser beam 6 interspersed wedge discs whose rotations when hitting a flat environment produce a scan line in the form of a Lissajous figure, or all other types of optically refractive elements are provided which are rotated or oscillated, for example, electrically controllable Lenses with electrically variable shape or electrically variable refractive index, eg electro-optical fluid lenses.

In order to automatically adjust the evaluation circuit 15 automatically to the respectively used scan head 3, 4 or an optionally used angle module 5, each scan head 3, 4 and also the optional angle module 5 can be equipped with a data carrier 46 having a unique identifier of Scan head 3, 4 or angle module 5 carries. In the data carrier 46, only one identifier can be stored which allows the evaluation circuit 15 to search for beam deflection properties of the respective scan head 3, 4 or angle module 5 stored in a database, or the data carrier 46 can itself provide the corresponding data of the scan head 3, 4 or angle module 5 included.

The data carrier 46 may be, for example, an optical data carrier, e.g. an inscription field or bar code 47, which faces the closing of the coupling device 24 of an optical reading device of the housing 2 and is optically detected by this, which is connected to the evaluation circuit 15. Alternatively and preferably, the data carrier 46 is radio-readable, e.g. an RFID tag (Radio Frequency Identification Tag), and can then be placed anywhere within the scan head 3, 4 or angle module 5. A corresponding reading device 48 in the housing 2 is then, for example, an RFID reader and can ausle-sen via radio the identifier or data of the currently anchored scan head 3, 4 and optionally one or more zwischengekuppelter angle modules 5 to set the evaluation circuit 15 thereon.

The invention is not limited to the illustrated embodiments, but includes all variants, modifications and combinations thereof that fall within the scope of the appended claims.

Claims (14)

claims A laser scanning system, characterized by the combination of a housing (2) with a transceiver (9) for a laser measuring beam (6) and a first window (10) for the passage of the laser measuring beam (6), a first scanning head (3) on one side with the first window (10) alignable second window (19) for the passage of the laser measuring beam (6) and behind a first motor-driven beam deflection means (18, 23), by means of which the laser measuring beam (6) to a a the first aperture (20) on a different side of the first scan head (3) passing through the first scan fan (6j is fanned, and a second scan head (4) on one side with the first window (10) alignable third window (34 ) for the passage of the laser measuring beam (6) and behind a second motorized beam deflection means (37, 41), by means of which the laser measuring beam (6) to a second aperture (39) on another side of the second S cankopfes (4), fanned from the first scan fan (6j different second scan compartments (6 "), wherein the first and the second scan head (3, 4) by means of a coupling device (24) modular against each other exchangeable on the housing (2) are anchored, so that in the anchoring position the first window (10) is aligned with the second or third window (19, 34). 2. Laser scanning system according to claim 1, characterized in that the first beam deflecting device (18, 23) rotates a motor-driven or swingable deflecting mirror (18) and the second beam deflecting device (37, 41) a motor-driven rotatable or vibratable optically refractive element (37 ) contains. 3. Laser scanning system according to claim 1 or 2, characterized in that the first beam deflecting device (18, 23) is a rotatable deflecting mirror (18) and the first aperture (20) is a 360 ° round window. 4. Laser scanning system according to claim 3, characterized in that the drive motor (23) of the deflection mirror (18) on the second window (19) facing away from the first scan head (3). 5. Laser scanning system according to one of claims 1 to 4, characterized in that the second beam deflection device (37, 41) is a rotatable wedge disk (37) made of transparent material. 6. Laser scanning system according to claim 5, characterized in that the drive motor (41) of the wedge disk (37) is a ring motor with an outer stator (43) and an inner annular rotor (44) which surrounds the wedge disk (37). 7. Laser scanning system according to claim 5, characterized in that the wedge disk (37) of at least three rollers (45) distributed over its circumference is mounted, of which at least one roller (45) is motor-driven. 8. Laser scanning system according to one of claims 5 to 7, that between the third window (34) and the wedge disk (37), a 90 ° -Umlenkspiegel is arranged. 9. laser scanning system according to one of claims 1 to 8, characterized in that it further comprises an angle module (5), which includes a deflection mirror (32), preferably a 90 ° -Umlenkspiegel, for the laser measuring beam (6) and by means of complementary coupling elements ( 25, 26) in the coupling device (24) between the housing (2) and the first or second laser head (3, 4) can be coupled. 10. Laser scanning system according to one of claims 1 to 9, characterized in that the coupling device (24) is a bayonet coupling (25, 26). 11. Laser scanning system according to one of claims 1 to 10, characterized in that the housing (2), the scan heads (3, 4) and the optional angle module (5) each have electrical contacts (29), via which in the anchoring position of the drive motor (23, 41) of the respective scan head (3, 4) can be supplied with power from a feed circuit (16) of the housing (2). 12. Laser scanning system according to one of claims 1 to 11, characterized in that each beam deflection device (18, 23, 37, 41) is equipped with an angle encoder (31) for its deflection angle, which angle encoder (31) in the anchoring position via further electrical contacts (30) of the housing (2) and the respective scan head (3, 4) to an evaluation circuit (15) of the housing (2) can be connected. 13. Laser scanning system according to one of claims 1 to 12, characterized in that the scan heads (3, 4) each have a data carrier (46) with a unique identifier of the scan head (3, 4), wherein the housing (2) with a reading device (48) is equipped for the data carrier (46). 14. Laser scanning system according to claim 13, characterized in that the data carrier (46) is an RFID tag (47).