EP2936054A1

EP2936054A1 - Method and device for determining the two-dimensional positional coordinates of a target object

Info

Publication number: EP2936054A1
Application number: EP13817674.8A
Authority: EP
Inventors: Torsten Gogolla; Andreas Winter
Original assignee: Hilti AG
Current assignee: Hilti AG
Priority date: 2012-12-20
Filing date: 2013-12-18
Publication date: 2015-10-28
Also published as: DE102012223929A1; WO2014095949A1; US20150346342A1; JP2016504585A; CN104870937A; US20180210085A1

Abstract

Disclosed is a method for determining the positional coordinates (X_M, Y_M) of a target object (11) in a measurement plane (12) in two dimensions, involving the following steps: a target device (13) with a reflector element (31) is positioned on the target object (11); a laser beam is transmitted towards the target device by a transmission element of a laser device (14) in an expansion direction (27) substantially parallel to the measurement plane (12); at least one part of the laser beam is partially reflected on the reflector element (31); an image of the target device (31) with the at least partially reflected laser beam as light reflex is captured by a camera device (15), a viewing direction (34) of the camera device (15) being inclined towards the measurement plane (12) at an elevation angle (φ); a centroid of the light reflex is determined in the image of the target device (13); from a focal length of the camera device (15), the elevation angle and a first and second image coordinate of the focal point of the light reflex in the coordinate system of the camera device, a first and second distance are calculated, and the positional coordinates of the target object (11) are calculated from the first and second distance.

Description

Method and device for determining the

two-dimensional spatial coordinates of a target object

Technical area

The present invention relates to a method for determining the two-dimensional spatial coordinates of a target object according to the preamble of claim 1 and to an apparatus for determining the two-dimensional spatial coordinates of a target object according to the preamble of claim 6.

State of the art

From EP 0 481 278 A1 a method and an apparatus for determining the two-dimensional location coordinates of a target object are known. The device comprises a laser distance measuring device, a camera device, a reference device and a control device. The laser distance measuring device has a transmitting element, which emits a laser beam, and a receiving element, which receives a laser beam, which is at least partially reflected at the target object, as a receiving beam. The reference means comprises first and second axes which are perpendicular to each other and span an internal coordinate system; a third axis of the coordinate system is perpendicular to the first and second axes through the intersection of the axes. The apparatus further comprises an angle measuring device for determining an azimuth angle. The target object is precisely sighted via the camera device and the target axis of the laser distance measuring device and the sighting axis of the camera device are aligned with the target object. The laser distance measurement is carried out by the laser distance measuring device and the azimuth angle is determined by the ultrasonic measuring device. The two-dimensional location coordinates are calculated from the distance value and the azimuth angle.

The known device for determining the location coordinates of a target object has the disadvantage that at least one angle measuring device is required, which increases the complexity and costs of the device for determining the location coordinates. In addition, the laser beam must be precisely aligned with the target object for laser distance measurement and angle measurement. Presentation of the invention

The object of the present invention is to develop a method for determining the two-dimensional spatial coordinates of a target object that is suitable for indoor use and that determines the location coordinates with little effort for the operator. In addition, a device suitable for the method according to the invention for determining the two-dimensional spatial coordinates of a target object is to be developed.

This object is achieved in the aforementioned method for determining the two-dimensional spatial coordinates of a target object according to the invention by the features of independent claim 1 and in the aforementioned device for determining two-dimensional spatial coordinates of a target object by the features of independent claim 6. Advantageous developments are specified in the dependent claims.

According to the invention, the method for determining the location coordinates of a target object in a measurement plane in two dimensions comprises the steps:

^■ a target device with a reflector element is positioned on the target object,

^■ a laser beam is emitted by a transmitting element of a laser device along a propagation direction substantially parallel to the measuring plane to the target device,

^At least part of the laser beam is partially reflected at the reflector element,

^■ an image of the target device with the at least partially reflected laser beam as a light reflex, is recorded by a camera device in which a view direction of the camera device is inclined at an elevation angle to the measuring plane,

^{■ In} the image of the target device, a center of gravity of the light reflection is determined,

^■ From a focal length of the camera device, the elevation angle and a first and second image coordinate of the center of gravity of the light reflection in the coordinate system of the camera device, a first and second distance are calculated, and

^■ The location coordinates of the target object are calculated from the first and second distances. Determining the location coordinates of a target object with the aid of a light reflection in an image of a camera device has the advantage that only one laser device is required in addition to the camera device. The fact that no Wnkelmesseinrichtung is required, a cost-effective device can be realized. The operator can determine the location coordinates of the target object with little effort. Preferably, a sequence of images of the target device is taken with the camera device. The laser beam which is directed onto the target device can be designed as a widened laser beam with an aperture angle greater than 80 °, as a moving laser beam or as a moving laser beam with an aperture angle smaller than 10 °. In the case of an expanded, non-moving laser beam, the laser beam is at least partially reflected at the reflector element of the target device and generates a light reflection in the image of the camera device. If the camera device takes a sequence of images of the target device, the light reflection is visible as long as the laser beam is emitted. In a moving laser beam, the camera device takes both images of the target device with light reflection and images without light reflection.

In a first variant of the method, the image with the strongest light reflection is determined as the image of the target device with the light reflection from the sequence of images taken with the camera device. The first variant is particularly suitable for moving laser beams, in which, as a result of the images taken with the camera device, images with a light reflex as well as images without a light reflex are present. The image with the strongest light reflection can be determined using known image processing techniques.

In a second variant of the method, the image of the target device with the light reflex is determined by averaging over a plurality of images from the sequence of images taken with the camera device. The second variant is particularly suitable for non-moving laser beams, in which the light reflection in the images is visible as long as the laser beam is emitted. The averaging over several images with a light reflex can be done using known image processing techniques.

In a preferred embodiment of the method, the recording of the images of the target device with the camera device and the emission of the laser beam from the laser device are simultaneously controlled by a control device.

In particular for carrying out the method according to the invention, the device according to the invention for determining the two-dimensional spatial coordinates of a target object in a measuring plane comprises:

^■ a target device with a reflector element which determines the location coordinates of the target object,

^■ a laser device with a transmitting element which emits a propagating along a propagation direction substantially parallel to the measuring plane laser beam, and a control element, ^■ a camera device with a receiving device and a control element, wherein a viewing direction of the camera device is inclined at an elevation angle to the measurement plane,

^■ a reference device having a first axis and a second axis, wherein the first and second axes are arranged perpendicular to each other and intersect at an intersection, and

^■ a control device with a control element for controlling the laser device and the camera device and an evaluation element for calculating the location coordinates of the target object. The device according to the invention for determining the two-dimensional spatial coordinates of a target object makes it possible to determine the spatial coordinates of a target object without an angle measuring device. Because no angle measuring device is required, a cost-effective device can be realized. The operator can determine the location coordinates of the target object with little effort. The reflector element is formed in a preferred embodiment as a rotationally symmetrical body or as a section of a rotationally symmetrical body. For two-dimensional measurements circular cylinder or circular cylinder sections are suitable as a reflector element. A rotationally symmetrical body has the advantage that the distance from the surface to the center is identical from all directions. The location coordinates of the target object lie on the cylinder axis of the circular cylinder. The radius of the circular cylinder is stored in the control device or is entered by the operator in the control device. For calculating the location coordinates, the radius of the destination device is taken into account in the calculation.

In a first variant, the laser device has a beam-shaping optical system which expands the laser beam in a direction parallel to the measuring plane with an opening angle greater than 80 °. In this case, the beam-shaping optical system collimates or focuses the laser beam particularly preferably in a direction perpendicular to the measurement plane. This beam-shaping optical system has the advantage that the available power of the laser beam is optimally utilized. In the determination of two-dimensional spatial coordinates in the measurement plane, no widening of the laser beam is required in the direction perpendicular to the measurement plane. The limited power of the laser beam is distributed by the beam shaping optics in the measurement plane. The widening of the laser beam by a beam-shaping optical system offers the possibility of using a stationary laser device.

The term "beam shaping optics" encompasses all beam-forming optical elements that expand, collimate or focus a laser beam. The Beam shaping optics can consist of an optical element in which one or more optical functions are integrated, or of a plurality of successively arranged optical elements. Cylindrical lenses, cone mirrors and similar optical elements are suitable as beam shaping optics for expanding a laser beam. In a second variant, the laser device has a motor unit, wherein the motor unit moves the laser beam about an axis of rotation perpendicular to the measurement plane. The rotation of the laser beam is useful if the power density of the laser beam after the expansion is too low to obtain a visible light reflection for the evaluation in the image of the camera device. The rotation of the laser beam about the axis of rotation perpendicular to the measuring plane can be carried out as a rotating, scanning or tracking movement. In the case of the rotating movement, the laser beam is continuously rotated about the axis of rotation, periodically reciprocated during the scanning movement about the axis of rotation, and during the tracking movement the laser beam follows the target device. The motor unit of the second variant can be combined with beam shaping optics that collimate or focus the laser beam.

In a third variant, the laser device has beam shaping optics and a motor unit, wherein the beam shaping optics expands the laser beam in a direction parallel to the measurement plane with an opening angle of up to 10 ° and the motor unit moves the laser beam about a rotation axis perpendicular to the measurement plane. The expansion of the laser beam and the rotation about a rotation axis can be combined. The laser beam is expanded by a beam shaping optics up to 10 ° and the expanded laser beam is moved by a motor unit about a rotation axis. The combination of beam expansion and rotation allows the detection of a receive beam with a sufficiently high power density for the evaluation of the light reflection. The rotation of the laser beam can be performed as a rotating, scanning or tracking movement.

In a first preferred embodiment, the target device of the device according to the invention is attached to a hand-held tool device. During processing with the hand-held tool device, the current location coordinates of the tool device can be determined with the device according to the invention. embodiments

Embodiments of the invention are described below with reference to the drawing. This is not necessarily to scale the embodiments, but the drawing, where appropriate for explanation, executed in a schematic and / or slightly distorted form. With regard to additions from the drawing directly recognizable teachings are referred to the relevant prior art. It should be noted that various modifications and changes may be made in the form and detail of an embodiment without departing from the general idea of the invention. The disclosed in the description, the drawings and the claims features of the invention may be essential both individually and in any combination for the development of the invention. In addition, all combinations of at least two of the features disclosed in the description, the drawings and / or the claims fall within the scope of the invention. The general idea of the invention is not limited to the exact form or detail of the preferred embodiment shown and described below or limited to an article that would be limited in comparison with the subject matter claimed in the claims. For given design ranges, values lying within the specified limits should also be disclosed as limit values and be arbitrarily usable and claimable. For simplicity, the same reference numerals are used below for identical or similar parts or parts with identical or similar function.

Show it:

FIG. 1 shows a device according to the invention for determining the two-dimensional

Location coordinates of a target object in a measurement plane with a target device, a laser device, a camera device, a reference device and a control device;

FIG. 2 shows the device of FIG. 1 with the laser device, the camera device and the control device in the form of a block diagram; and

FIG. FIG. 3 shows an image of the aiming device taken with the camera device with a reflected laser beam as the light reflex, which is evaluated for determining the location coordinates of the target object.

FIG. 1 shows a first device 10 according to the invention for determining the location coordinates X _M , Y _{M of} a target object 1 1 in a measurement area 12. The measurement area 12 is designed as a measurement plane and the location coordinates X _M , Y _{M of} the target object 11 are two-dimensional.

The device 10 comprises a target device 13, a laser device 14, a camera device 15, a reference device 16, a control device 17 and a handpiece 18. The laser device 14, the camera device 15, the reference device 16 and the control device 17 are integrated in a measuring device 19, that in the in FIG. 1 illustrated embodiment is mounted on a device stand 20. The handpiece 18 has a control ment 21, a display device 22 with a display 23 and an operating device 24. As an alternative to the arrangement in the measuring device 19, the control device 17 may be arranged in the handpiece 18. The measuring device 19 and the handle 18 are connected to each other via a wireless communication link 25. Alternatively to FIG. 1 shown separation of target device 13 and handle 16, the target device may be integrated into the handle.

The reference device 16 comprises a first and second axis 26, 27, which are arranged perpendicular to each other and intersect at an intersection point 28. The first and second axes 26, 27 span an internal coordinate system of the measuring device 19. A third axis 29 extends perpendicular to the first and second axes 26, 27 through the intersection 28 of the two axes 26, 27. A plane spanned by the first axis 26 and the second axis 27 extends parallel to the measurement plane 12 and the propagation direction of the laser device 14 extends parallel to the second axis 27. If the location coordinates of the target object 11 are to be determined in an external coordinate system that deviates from the internal coordinate system 26, 27 of the measuring device 19, the coordinate systems are superimposed or the displacement and / or rotation between the external coordinate system and the internal coordinate system of the measuring device 19 is determined and entered manually on the measuring device 19 or automatically transmitted to the control device 17. The position of the target object 1 1 in the measurement plane 12 is marked by means of the target device 13. The aiming device 13 has a reflector element 31 for reflecting a laser beam of the laser device 14. The reflector element 31 is in the in FIG. The spatial coordinates of the target object 11 are on the cylinder axis 32 of the reflector element 31. It is important for the device 10 according to the invention that the spatial coordinates of the target object 11, which are arranged in the center, the same for each point on the surface Have distance. The radius R of the circular cylinder 31 is stored in the controller 17 or is input to the controller 17 by the operator. The reflector element 31 can be attached to a staff 33 and is positioned by the operator on the target object 1 1. In order to align the cylinder axis 32 of the reflector element 31 perpendicular to the measuring plane 12, a leveling device, for example in the form of a dragonfly or another inclination sensor, may be integrated into the measuring rod 33. As an alternative to the yardstick 33, the target device 13 may be attached to a wall or a ceiling, placed on a floor, or fastened to, for example, a vehicle or a tool device.

The laser device 14 emits a laser beam, which is directed to the target device 13. The propagation direction of the laser beam of the laser device 14 is parallel to the second axis 27 and parallel to the measuring plane 12. In order to determine the location coordinates X _M , YM of the target object 11 via a laser beam reflected at the target device 13, a viewing direction 34 of the camera device 15 must be inclined at an elevation angle φ to the measurement plane 12. The coordinate system of the camera device 15 is rotated by the elevation angle φ relative to the internal coordinate system 26, 27 of the measuring device 19 and shifted by a distance. The camera device 15 may be designed to be rotatable about an axis of rotation or about a pivot point. Due to the rotatability of the camera device 15, the viewing direction 34 of the camera device 15 can be aligned with the center of the measuring range. The coordinate origin of the coordinate system of the camera device 15 can additionally be shifted relative to the coordinate origin of the internal coordinate system 26, 27 of the measuring device 19. The rotation of the coordinate system of the camera device 15 with respect to the elevation angle relative to the internal coordinate system is necessary for the determination of the location coordinates, the displacement and a rotation with respect to an azimuth angle, however, not. If a displacement and a rotation with respect to the azimuth angle are present, these quantities must be known and, in addition to the determination of the location coordinates, taken into account in the internal coordinate system of the measuring device 19.

In addition to the determination of location coordinates of an existing target object, the device 10 can also be used to find location coordinates. For this purpose, the user guides a reflector element equipped with a measuring tip or the like, which can also be integrated in the handpiece, over a measuring surface and searches for predetermined location coordinates. The location coordinates can be entered manually in the handset or they can be transmitted via a communication link from another device to the device.

FIG. 2 shows the essential components of the measuring device 19 and their interaction in the determination of the location coordinates of the target object 11 in the form of a block diagram. The laser device 14 includes a laser element configured as a transmitting element 41, a beam shaping optics 42 and a control element 43. The laser diode 41 emits a laser beam 44 which is on the target device 13th is directed. The beam shaping optics 42 may be formed as a single optical element or as a system of multiple optical elements. In order to be able to determine the location coordinates of moving target objects, it is necessary for the device 10 according to the invention that the laser beam 44 has a recorded larger angle range. This can be achieved by widening the laser beam 44 in the measurement plane 12 or by rotating the laser beam 44 about an axis of rotation perpendicular to the measurement plane 12. FIG. FIG. 2 shows a laser distance measuring device 14, in which the laser beam 44 is widened by means of a suitable beam-shaping optical system 42. For example, cylindrical lenses and cone optics are suitable as beam shaping optics 42 for widening.

The camera device 15 is designed for example as a CCD camera and comprises a receiving device 45 and a control element 46 for controlling the camera device 15 and for evaluating the recorded images. The control device 17 controls the inventive method for determining the location coordinates of the target object 11 by means of the laser device 14 and the camera device 15. The control device 17 comprises a control element 47 for controlling the laser device 14 and the camera device 15 and an evaluation element 48 for calculating the location coordinates X _M , YM of the target object 11. The operator starts the determination of the location coordinates via a start command on the handpiece 18. The start command is converted by the control element 48 of the control device 17 into a first control command to the laser device 14 and a second control command to the camera device 15. On the basis of the first control command, the transmitting element 41 of the laser device 14 emits the laser beam 44, which strikes the reflector element 31 and is partially reflected at the reflector element 31. Due to the second control command, the camera device 15 records a sequence of images of the target device 13. The laser beam 46 partially reflected at the reflector element 31 is visible in at least one image of the target device 13 as a light reflection. The control element 46 of the camera device 15 uses known image processing techniques to determine, for example, the image of the target device 13 that has the strongest light reflection. As an alternative to the image with the strongest light reflex, several images in which a light reflex is visible can be used.

FIG. 3 shows an image 61 of the target device 13 with a light reflection 62, which is evaluated for the determination of the location coordinates X _M , Y _{M of} the target object 1 1. The image 61 consists of an array of pixels arranged in rows and columns, the number of pixels being determined by the resolution of the camera device 15.

In the image 61 of the target device 13, a center of gravity 63 of the light reflection 62 is determined by means of known image processing techniques by the control element 46 of the camera device 15. The center of gravity 63 of the light reflection 62 has, in the coordinate system of the camera device 15, a first image coordinate X _s and a second image coordinate Y _s . From the image coordinates X _s , Ys of the center of gravity 63 of the light reflection 62 in the coordinate system The camera device 15 is calculated with a focal length f of the camera device 15 and the rotation and a possible shift of the coordinate system of the camera device 15 to the internal coordinate system 26, 27 of the measuring device 19, a first distance c and a second distance d ₂ . The location coordinates X _M , Y _{M of} the target object 1 1 are then calculated from the first and second distances d ₂ d ₂ .

Claims

Method for determining the location coordinates (XM, Y _m ) of a target object (11) in a measurement plane (12) in two dimensions (X, Y), comprising the steps:

^■ a target device (13) with a reflector member (31) is positioned at the target object (1: 1),

^■ a laser beam (44) from a transmitting element (41) a laser device (14) along a propagation direction (27) substantially parallel to the measuring plane (12) sent to the target device (13),

^At least a part of the laser beam (44) is partially reflected at the reflector element (31),

^■ An image (61) of the aiming device (13) with the at least partially reflected laser beam (44) as light reflection (62) is recorded by a camera device (15), wherein a viewing direction (34) of the camera device (15) at an elevation angle (φ) is inclined to the measurement plane (12),

^■ in the image (61) of the target device (13), a center of gravity (63) of the light reflection (62) is determined,

^■ from a focal length (f) of the camera device (15), the elevation angle (φ) and a first and second image coordinate (X _S , Ys) of the light reflection (62) a first and second distance (d ^ d ₂ ) are calculated,

^■ the spatial coordinates (X _M , YM) of the target object (11) are calculated from the first and second distances (di, d ₂ ).

A method according to claim 1, characterized in that a sequence of images of the target device (13) with the camera device (15) is received.

Method according to Claim 2, characterized in that the image with the strongest light reflection is determined as the image (61) of the target device (13) with the light reflex (62) from the sequence of images taken with the camera device (15).

A method according to claim 2, characterized in that the image (61) of the target device (13) with the light reflection (62) by averaging over a plurality of images from the sequence of images taken with the camera device (15) is determined.

Method according to one of claims 2 to 4, characterized in that the recording of the images of the target device (13) with the camera device (15) and the emission of the laser beam (44) from the laser device (14) simultaneously controlled by a control device (17) become.

6. Apparatus (10) for determining the location coordinates (X _M , Y _M ) of a target object (1 1, 51) in a measurement plane (12) in two dimensions (X, Y) for carrying out a method according to one of claims 1 to 5, comprising:

^■ a target device (13) having a reflector element (31) which determines the location coordinates (XM, YM) of the target object (1 1),

^■ a laser device (14) having a transmission element (41) which has a along a propagation direction (27) substantially parallel to the measuring plane propagating (12) laser beam (44) emits,

^■ a camera device (15) with a receiving device (45) and a control element (46), wherein a viewing direction (34) of the camera device (15) under a

Elevation angle (φ) is inclined to the measurement plane (12),

^■ a reference device (16) having a first axis (26) and a second axis (27), wherein the first and second axes (26, 27) are perpendicular to each other and intersect at an intersection (28), and

■ a control device (17) with a control element (47) for controlling the laser device (14) and the camera device (15) and an evaluation element (48) for calculating the location coordinates (X _M , YM) of the target object (11).

7. Apparatus according to claim 6, characterized in that the reflector element is designed as a rotationally symmetrical body (31) or as a section of a rotationally symmetrical body.

8. Device according to one of claims 6 to 7, characterized in that the laser device (14) comprises a beam shaping optics (42), the laser beam (44) in a direction substantially parallel to the measuring plane (12) with an opening angle greater than 80 ° expands. 9. Apparatus according to claim 8, characterized in that the beam-shaping optical system (42) collimates or focuses the laser beam (44) in a direction substantially perpendicular to the measuring plane (12).

10. Device according to one of claims 6 to 7, characterized in that the laser device (14) comprises a motor unit, wherein the motor unit moves the laser beam (44) about a plane perpendicular to the measuring plane (12) axis of rotation.

1 1. Device according to one of claims 6 to 7, characterized in that the laser device (14) comprises a beam shaping optics and a motor unit, wherein the beam shaping optics, the laser beam (44) in a direction substantially parallel to Measuring plane (12) widens with an opening angle of up to 10 ° and the motor unit moves the laser beam (44) by a plane perpendicular to the measuring plane (12) axis of rotation.

12. Device according to one of claims 6 to 1 1, characterized in that the target device is attached to a hand-held tool device.