WO2003087875A1

WO2003087875A1 - Device for generating a three-dimensional ambient image

Info

Publication number: WO2003087875A1
Application number: PCT/DE2003/001147
Authority: WO
Inventors: Reinhard Becker; Heinrich HÖFLER; Andreas Sutorius; Harald WÖLFELSCHNEIDER
Original assignee: Iqsun Gmbh
Priority date: 2002-04-12
Filing date: 2003-04-08
Publication date: 2003-10-23
Also published as: DE10216405A1

Abstract

Disclosed is a device for generating a three-dimensional ambient image, comprising a radiation source (1, 4, 22, 23), a beam-deflecting unit (6) that is provided with a rotating mirror (7), a receiving optical system (17), a detector unit (18), and a reference unit (20), which are mounted on a mechanically stable support (19) along axes that coincide or are perpendicular to each other, whereby adjustments are relatively easy to make and a reference path is formed for correcting distance-related data, said reference path not being modifiable in the framework of accuracy of measurement. For functional purposes, the inventive device is provided with a cover (11) and a beam trap (24) absorbing disturbing reflective radiation components.

Description

Device for generating a three-dimensional environment image

The invention relates to a device for generating a three-dimensional environmental image according to the preamble of patent claim 1.

Such a generic device is known from DE 198 12 431 A1. In the known device, the surroundings are scanned using a tripod by swiveling a scanning beam in the horizontal direction by 360 degrees and in a direction essentially perpendicular thereto by 180 degrees. A disadvantage of this device, however, is a relatively large inaccuracy both in determining the distance and in the adjustment.

The invention has for its object to provide a generic device, which is characterized by a relatively simple adjustment and a very high accuracy in determining the distance.

This object is achieved in a generic device with the characterizing features of claim 1.

Characterized in that the direction of propagation of the scanning beam, the optical axis of the receiving optics and the axis of rotation of the mirror wave are aligned collinearly to one another, that the elements determining the propagation time of the scanning beam and reflected radiation within the device are connected to one another via the carrier and also by the provision of a the reference unit connected to the carrier is on the one hand the adjustment very simplified and unchangeable within the scope of the measuring accuracy of the device Reference way created a correction option for, for example, relatively inaccurate distance data due to temperature drifts.

It is particularly expedient to provide a cover which surrounds the rotating mirror and which is transparent to the scanning beam and the reflected electromagnetic radiation at least in the region of the beam path, and a beam case which is designed and arranged such that reflections caused by the cover when it passes through the cover can be absorbed are. This prevents radiation components belonging to such reflections from affecting the detector unit and impairing the accuracy of the distance measurement.

Further expedient refinements of the device according to the invention are the subject of the dependent claims.

Further expedient refinements and advantages of the invention are the subject of the following description of

Embodiments with reference to the accompanying figures.

Show it:

1 is a schematic representation of the structure of an embodiment of a device according to the invention,

2 shows a schematic representation of the structure of a further exemplary embodiment of a device according to the invention,

Fig. 3 in a detailed schematic representation of the structure of a cover and a beam trap in one another embodiment of a device according to the invention,

4 shows a detailed schematic illustration of the structure of a cover and a beam trap in a further exemplary embodiment of a device according to the invention,

5 shows a detailed schematic representation of the exemplary structure of a reference unit in one

Embodiment of a device according to the invention,

6 shows a view of an embodiment of a surface of the reference unit according to FIG. 5,

7 shows a view of a further embodiment of a surface of the reference unit according to FIGS. 5 and

8 is a block diagram showing the execution of a central unit according to an apparatus according to the invention.

Fig. 1 shows a schematic view of the structure of an embodiment of a device according to the invention. The exemplary embodiment according to FIG. 1 has a laser unit 1 as the radiation source, which has a laser 2 and collimation optics 3. The laser unit 1 is connected to a laser control unit 4, with which a scanning beam 5 which can be emitted by the laser 2 can be intensity-modulated, preferably in pulse-like or high-frequency sine-like manner.

Furthermore, the device according to FIG. 1 is equipped with a beam deflection unit 6, which has a rotating mirror 7 aligned at an angle of 45 degrees to the scanning beam 5. The rotating mirror 7 is attached to a mirror shaft 8 brings, which can be rotated 360 degrees via a motorized mirror drive 9. Thus, the scanning beam 5 can be deflected by the rotating mirror 7 by 90 degrees and pivoted by 360 degrees in a scanning plane perpendicular to the drawing plane of FIG. 1. To detect the position of the mirror shaft 8, an encoder 10 is connected to the mirror drive 9.

In the exemplary embodiment according to FIG. 1, there is a cover 11 which surrounds the rotating mirror 7 and is permeable to the scanning beam 5 and which has an inner cone surface 12 and an outer cone surface 13. The surfaces of the cone surfaces 12, 13 aligned to avoid interference with different angles of attack against the scanning beam 5 are inclined in the direction of the laser unit 1, so that reflections caused on the cone surfaces 12, 13 when the scanning beam 5 passes are reflected in the direction of the beam deflection unit 6 , The dimensions of the cover 11 and the beam deflection unit 6 are set up in such a way that the reflections past the rotating mirror 7 fall into a cylindrical beam trap 14 which is connected to the mirror shaft 8 and has an opening in the direction of the impact area of the scanning beam 5 on the cone surfaces 12, 13 and are absorbed in the beam trap 14.

In the illustration according to FIG. 1, the scanning beam 5 emerging from the cover 11 acts on a surface 15 of an object in a scanning area. Radiation 16 which is reflected back from the surface 15 in the direction of the rotating mirror 7 can be deflected by the rotating mirror 7 onto a receiving optics 17 with which the reflected radiation 16 of a detector unit 18 can be fed.

1, the laser unit 1 is arranged on the optical axis of the receiving optics 17 and on the side pointing in the direction of the rotating mirror 7. brought so that the scanning beam 5 spreads on the optical axis of the receiving optics 17. Furthermore, the mirror shaft 8 is arranged such that its axis of rotation coincides with the optical axis of the receiving optics 17 and the direction of incidence of the scanning beam 5 on the rotating mirror 7.

The ^"mirror drive 9 of the beam deflection unit 6 and the detector unit 18 are mounted on a mechanically stable substrate 19th Further, on the support 19, a reference unit 20 that will be acted upon at a corresponding position of the rotary mirror 7 of the scanning beam. 5

The exemplary embodiment according to FIG. 1 is further equipped with a central unit 21, which is explained in more detail below, to which the laser control unit 4, the encoder 10, the detector unit 18 and the reference unit 20 are connected.

FIG. 2 shows a schematic illustration of a further exemplary embodiment of a device according to the invention, in which corresponding elements in FIG. 1 and FIG. 2 are provided with the same reference symbols and are not explained in more detail below. In the exemplary embodiment according to FIG. 2, the laser unit 1 of the radiation source is coupled to an optical fiber 22. A coupling-out optical system 23, which is arranged on the end of the optical fiber 22 facing away from the laser unit 1, is attached centrally to the receiving optical system 17, so that the scanning beam 5 coincides with the optical axis of the receiving optical system 17.

In the exemplary embodiment according to FIG. 2, the cover 11 formed with two cone surfaces 12, 13 inclined towards one another is opened in the direction of the receiving optics 17 or the detector unit 18, so that reflections reflected by the cone surfaces 12, 13 are deflected in this direction. The dimensions of the cover 11 are at 2 set up such that the reflections fall into an annular beam trap 24 arranged around the optical axis of the receiving optics 17 and are absorbed therein between two ring disks and an outer ring.

2 is designed with a carrier drive 25 which is mechanically connected to the carrier 19 via a carrier shaft 26. The axis of rotation of the carrier shaft 26 is oriented at right angles to the axis of rotation of the mirror shaft 8 and runs through the area of incidence of the scanning beam 5 on the rotating mirror 7. The reference unit 20 is also on the axis of rotation of the carrier shaft 26. The carrier drive 25 is also connected to the central unit 21 - closed.

The carrier 19 of the device according to the invention according to FIG. 2 can thus be pivoted about the axis of rotation of the carrier shaft 26, it being noted that for a complete recording of a spatial image of the surroundings when the rotating mirror 7 is rotated through 360 degrees, a pivoting through 180 degrees is sufficient.

3 shows a detailed schematic illustration of the structure of a cover 11 formed with conical surfaces 12, 13 inclined towards one another and a cylindrical beam trap 14 in a further exemplary embodiment of a device according to the invention. In the exemplary embodiment according to FIG. 3, the cylindrical beam trap 14 is attached to the rotating mirror 7 in such a way that it encloses the scanning beam 5 entering via a lateral recess between the rotating mirror 7 and the cover 11 and reaches relatively close to the inner conical surface 12. Reflections reflected in the cylindrical beam trap 14 are thus absorbed by the conical surfaces 12, 13 inclined against the scanning beam 5. 4 shows a detailed schematic illustration of the structure of a cover 11 and an annular beam trap 24 in a further exemplary embodiment of a device according to the invention. In the exemplary embodiment according to FIG. 4, the cover 11 is composed of a cylindrical first cylinder segment 27 facing the receiving optics 17 (not shown in FIG. 4), a cylindrical cylinder facing the mirror drive 9 and a second cylinder segment 28 which is larger than the diameter of the first cylinder segment 27 and a cone segment 29 arranged between the first cylinder segment 27 and the second cylinder segment 28. The transparent cover 11 is arranged such that the scanning beam 5 passes through the cone segment 29. The annular beam trap 24, which is constructed from two ring disks, is arranged in the exemplary embodiment according to FIG. 4 such that the scanning beam 5 runs within the annular beam trap 24 in a section adjoining the cover 11. As a result, reflections generated on the surface of the cone segment 29, which is inclined against the scanning beam 5, are absorbed on the annular disks.

5 shows a detailed schematic illustration in a side view of the exemplary structure of a reference unit 20 in an exemplary embodiment of a device according to the invention. The reference unit 20 according to FIG. 5 has a beam offset module 30, a reflecting first surface 31 and a second surface 32 with an at least partially scattering surface structure which lies opposite the first surface 31. The first surface 31 is arranged in the corresponding and shown in FIG. 5 position of the rotating mirror 7 in the direction of the deflected scanning beam 5 and inclined thereto and directs the scanning beam 5 onto the second surface 32. The radiation 16 reflected by the second surface 32 falls again on the rotary mirror 7 and acts on the receiving optics 17 (not shown in FIG. 5). Thus, the laser unit 1 according to the exemplary embodiment is exactly known due to the measuring accuracy of the device according to the invention and is fastened 1 or the decoupling optics 23, not shown in FIG. 5, of the optical fiber 22 according to the exemplary embodiment according to FIG. 2, the beam deflection unit 6 and that of the receiving optics 17 and detector unit 18 not shown in FIG A distance calibration of the scanning beam 5 can be carried out, in particular to compensate for temperature-related drifts in the characteristics of the laser unit 1 and the detector unit 18.

Furthermore, the reference unit 20 is equipped with at least one, but preferably with a plurality of differential photodiodes 33, which are arranged in recesses made in the rear of the second surface 32 in the beam displacement module 30 and also through the second surface 32.

6 shows a front view of an embodiment of the second surface 32 of a reference unit 20 according to FIG. 5 formed with a differential photodiode 33. In the embodiment according to FIG. 6, the second surface 32 is oriented transversely to the direction of incidence of the scanning beam 5 Scanning direction is formed with a number of absorption segments 34 to 38, each with a different degree of blackening, preferably increasing or decreasing in one direction. The differential photodiode 33 is arranged in the region of the middle absorption segment 36.

FIG. 7 shows a front view of a further embodiment of the second surface 32 with three differential photodiodes 33 5. In the embodiment according to FIG. 7, the second surface 32 is formed in a scanning direction oriented transversely to the direction of incidence of the scanning beam 5 with a degree of blackening which increases or decreases continuously in one direction. Two differential photodiodes 33 are arranged in edge areas and the third differential photodiode 33 in the center area of the second surface 32.

Due to the thus changing intensity of the reflected radiation 16 when the scanning beam 5 passes through the second surface 32 according to FIG. 6 or FIG. 7, an intensity calibration can be carried out.

Each of the differential photodiodes 33 is formed with two adjoining detection segments, each of which has essentially the same area and the same sensitivity, and which are connected in a complementary manner to one another in terms of voltage. When a scanning beam 5 passes through the second surface 32, this results in a high spatial resolution due to the zero crossing of the voltage kuπ / e of each differential photodiode 33, and when several differential photodiodes 33 are provided, there is also a high speed resolution for the movement of the scanning beam 5.

8 shows in a block diagram the execution of a central unit 21 according to a device according to the invention. The central unit 21 has a distance measuring device 39 which has a transmission module 40 and a reception module 41. The transmitter module 40 is equipped with a modulator 42 and with a laser driver 43 which is connected to the modulator 42 and which applies control signals for intensity modulation to the laser control unit 4. The reception module 41 comprises one connected to the detector unit 18 Detector signal pickup 44, a detector signal amplifier 45 arranged downstream of the detector signal pickup 44, a distance determining element 46 connected to the modulator 42 and the detector signal amplifier 45, and an intensity calibration element 47 connected to the detector signal amplifier 45 Scanning beam 5 and the reflected radiation 16, a distance signal can be generated. Under certain circumstances, the intensity calibration element 47 can be used to correct nonlinear dynamic characteristic curves leading to incorrect distance measurements.

Furthermore, the central unit 21 has a drive module 48 which has a motor control 49 for the mirror drive 9 and for the carrier drive 25. The drive module 48 is further equipped with an angle sensor 50, a reference sensor 51 which detects the reference path and scanning speed determined by the reference unit 20 and an incline sensor 52 which determines the inclination of the support 19.

The central unit 21 also has a control module 53 with a speed sensor 54 connected to the laser driver 43 to reduce the intensity of the scanning beam 5 when the speed falls below a predetermined speed, and a drive control element 55.

A processing device 56 of the central unit 21 has a data acquisition module 57 and a computing module 58.

The data acquisition module 57 has a data buffer 59 which is connected to the distance determination element 46 and the intensity calibration element 57 and works according to the FIFO (first-in, first-out) principle, and has a Encoder 50 connected angle data generator 60 and via a position encoder 61 connected to the inclination sensor 52.

Finally, the computing module 58 is equipped with a reference value generator 62 which is connected to the reference path encoder 51, the data buffer 59 and the angle data generator 60 and with which, taking into account the reference path and the angle data recorded in the process, correction data can be generated, which is also provided by the data buffer 59 connected image data memories 63 can be supplied for correcting the distance data and angle data.

Coordinate data can be determined from the angle data and the distance data in spherical coordinates in a bidsynthesis element 64 arranged downstream of the image data memory 63 and connected to the angle data generator 60. The coordinate data from the image synthesis element 64 can be fed to a coordinate transformer 65, by means of which the coordinate data can preferably be converted into a Cartesian coordinate system and can be displayed in a downstream display element 66 together with the distance data forming the image data, or can be stored in a surrounding image memory (not shown in FIG. 8).

Sets of operating parameters characteristic of different operating modes can be stored in a parameter memory 67 of the computing module 58 connected to the drive control element 55, and the drive control element 55 can be fed in.

Claims

1. Device for generating a three-dimensional environmental image with an electromagnetic radiation source, with which an intensity-modulated scanning beam can be generated, with a beam deflection unit that can be acted upon by the scanning beam, with a receiving optic with which electromagnetic radiation reflected from a surface can be directed onto a detector unit, and with a central unit with which it is possible to generate from the runtime of the scanning beam and the reflected radiation significant angle data for the direction of the scanning beam and for distances between the device and the surface

Distance data three-dimensional image data for spatial representation of the surroundings of the device can be generated, characterized in that the beam deflection unit (6) has a rotating mirror (7) which is attached to a rotatable mirror shaft (8) of a mirror drive

(9) that the axis of rotation of the rotating mirror (7), the direction of propagation of the scanning beam (5) and the optical axis of the receiving optics (17) are aligned coaxially, that at least one optical system (3, 23 ) the radiation source (1), the

Beam deflection unit (6), the receiving optics (17) and the detector unit (18) connecting carrier (19) is present, and that a reference unit (20) is provided on the carrier (19) and can be acted upon by the scanning beam (5) , with which a reference signal which can be fed into the central unit (21) and is significant for an unchangeable reference path within the scope of the measuring accuracy can be generated when the scanning beam (5) is applied.

2. Device according to claim 1, characterized in that there is a carrier drive (25) connected to the carrier (19) via a carrier shaft (26), with which the carrier (19) is rotatable, the axis of rotation of the carrier shaft (26) is aligned at right angles to the axis of rotation of the mirror shaft (8) and runs through the area of incidence of the scanning beam (5) on the rotating mirror (7).

3. Device according to claim 1 or claim 2, characterized in that a cover (11) surrounding the rotating mirror (7) is provided with a surface (12, 13, 29) inclined in the area of incidence of the scanning beam (5) against the scanning beam (5) is.

4. The device according to claim 3, characterized in that a beam trap (14, 24) is present, with which radiation reflected from the cover (11) can be absorbed.

5. Device according to one of claims 1 to 4, characterized in that the radiation source comprises a laser unit (1) arranged on the optical axis of the receiving optics (17) with a laser (2) and a collimation optics (3).

6. Device according to one of claims 1 to 4, characterized in that the radiation source comprises an optical fiber (22) which is coupled at one end to a laser unit (1) and at the other end together with a coupling optics (23) the receiving optics (17) is connected.

7. Device according to one of claims 1 to 6, characterized in that the reference unit (20) has at least one differential photodiode (33).

8. Device according to one of claims 1 to 7, characterized in that the reference unit (20) has an inclined first surface (31) facing the scanning beam (5) and a second surface (32) opposite the first surface (31), wherein the second surface (32) is oriented so that radiation (16) can be reflected back onto the rotating mirror (7).

9. The device according to claim 8, characterized in that the first surface (31) is reflective and the second surface (32) is formed with an at least partially scattering surface structure.

10. The device according to claim 8 or claim 9, characterized in that a surface (31, 32) in a scanning direction oriented transversely to the direction of incidence of the scanning beam (5) has a changing absorption.

11. The device according to one of claims 1 to 10, characterized in that the central unit (21) an angle data generator (60) for generating angle data significant for the alignment of the scanning beam (5) and a distance determining element (46) for generating the runtime of the scanning beam (5) and reflected radiation (16) has significant distance data and a reference path transmitter (51) connected to the reference unit (20), with which a distance correction signal and an angle correction signal for correcting the distance data or the angle data can be generated.

2. Device according to one of claims 2 to 11, that the central processing unit (21) has an image synthesis element (64) with which, in the case of a partial rotation of the carrier (19) corresponding to half of the spatial area to be detected, distance data and angle data from the two partial areas to one complete environment image can be put together.