JP2003503684A - Measuring device for measuring the position and orientation of the first part to be worked, inspected or moved - Google Patents

Abstract

(57) Abstract: A device for measuring the position and orientation of a first component (1) to be worked, inspected or moved, wherein the first component (1) is held by the device or Separate from the end effector (2); at least two imaging devices (3a, 3b), each attachable to the end effector (2), each of the first part (1). At least two imaging devices (3a, 3b) configurable to image a first surface (4); a plurality of first light sources (5), active light sources or illuminable reflections A point, or both, which can be positioned on the first part (1), so that when positioned on the first surface (4) of the first part (1), the first part When light is projected or reflected from each of the light sources (5), the light A distribution is generated at each of the at least two imaging devices (3a, 3b), wherein each of the at least two imaging devices (3a, 3b) is indicative of a distribution of light received by each imaging device (6a, 3b). A plurality of first light sources (5) operable to output 6b); a processor (7) for receiving and processing an output signal indicative of a distribution of light from each of said imaging devices (3a, 3b). And calibrating the output signals (6a, 6b) operatively associated with the processor (7) and indicating the distribution of light processed by the processor (7), and the position and orientation of the first component (1). A calibration means (12) for determining

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring device for measuring the position and orientation of a first part to be worked, inspected or moved.

BACKGROUND OF THE INVENTION To work, inspect, or move a single component individually or between multiple objects and other components, one must know its position and orientation.
Choosing the right measurement system to generate this information depends on environment, accuracy, proximity, time,
Depending on many factors, including space and space constraints, traditional measurement systems should be broadly divided between those that require contact with the part being measured and those that do not. You can

Various contact measurement devices have been developed that have a touch probe device at one end that registers contact with a feature or object on a part, with numerous pin joints angled along its length. Have pin-jointed angled connections. The degree of measurement is determined from the number of connections, and is generally 6.
Each joint is precision machined to a certain tolerance and each joint is combined to give the individual overall system accuracy. The obvious limitation in such systems is the need for a touch probe to contact the part being measured,
This limits the range of applications.

Laser trackers are non-contacting polar devices that use interferometers and are commonly used to measure elevation, azimuth, and range of a single retroreflective target. Typical systems require the positioning of corner cubes (tooling balls) to redirect the laser beam arriving at various locations on the part. The most important limitation of this type of system is that the system only measures 3D position and does not provide information about the orientation of the part.

Conventional methods of photogrammetry, such as film photogrammetry, use a retroreflective target on the surface of the object of interest, an expensive precision geometrically stable camera, and silver film applied photoimaging. Moreover, it requires the assistance of a skilled operator. Such a method is very accurate and can reach one part of the one million object space, but at the time disadvantage of chemically processing the photographic material, manual or semi-automatic measurement. The time required and the expertise required to reach full measurement potential make conventional photogrammetry methods unsuitable for most manufacturing operations. However, gradual position measurements, e.g. structures such as steel bridges under load or moving in dams or reservoir embankments, require very accurate data over long periods of time, This method is well suited.

With the advent of geometrically stable charge-coupled device (CCD) cameras, considerable progress has been made in the development of real-time digital photogrammetry systems, with the large number of objects in a specific application of the assembly process in a manufacturing environment. The degree of freedom can be measured. In essence, the image of the illuminated high-contrast target is positioned on the part to be worked, tested, or inspected, captured by a CCD camera, and processed to give a measure of the position of that part. Most of the configurations currently used to perform these measurements place the CCD camera at a distance from the part to be measured and work with the CCD camera to achieve sufficiently accurate measurements. It requires high light quality in the imaging device, eg lens. In this type of measurement, the measuring device is typically set up in the'workcell 'area and the part to be worked, tested or inspected comes into the workcell to make the measurement. The costs involved in assembling the parts, the measurement system, and the hardware required to perform the measurements, such as the imaging system described in detail above, make such a system very expensive.

Photogrammetry systems place imaging devices (which may be CCD cameras) on the robot body and robotize these components rather than when the imaging devices are mounted away from the components being worked on. Developed to get closer to. Nevertheless, the photogrammetric system still constrains them to the cell in which the robot is mounted, since the parts to be worked on are generally substantial objects.

[0008] Therefore, the use of inexpensive and standard imaging devices, and the need, are needed because of the need for an overall improved measurement system in which the part to be measured can be moved to the location where it is located. If so, it made it possible to adapt to various control devices such as robots and mechanical tools.

SUMMARY OF THE INVENTION According to a first aspect of the present invention, an apparatus for measuring the position and orientation of a first part to be worked, inspected or moved, the first part being the device. Held by or separate from the device: end effector; at least two imaging devices, each connectable to the end effector, each imaging the first side of the first part At least two imaging devices configurable to include: a plurality of first light sources, the light sources being active and / or the illuminatable reflection points, or both, and may be located on the first component. , And thus the distribution of light when the light is projected or reflected from each of the first light sources when positioned on the first surface of the first component, the distribution of light is at least two imaging devices. It is generated in each of at least two of the first plurality which can be operated to output a signal of each of the imaging device showing a distribution of light received by each imaging device of the light source;
A processor for receiving and processing a light distribution output signal from each of the imaging devices; and operatively associated with the processor to calibrate the light distribution output signal processed by the processor; And a calibration means for determining the position and orientation of the components of the.

The end effector preferably comprises means for mounting the second component thereon.

Conveniently, each of the at least two imaging devices is a metrology (acting in art) sensor that operates to produce a digitizable image.

[0012] At least two second light sources, each associated with each imaging device, the plurality of first light sources being a plurality of reflective targets, each positionable on the first component. Is effective.

[0013]   Preferably, each of the plurality of reflective targets is made of retroreflective material.

Conveniently, the plurality of reflective targets comprises at least six reflective targets, each non-planar and non-linearly spaced from one another.

A communication link between the imaging device and the processor for transmitting an output signal indicative of light distribution at each of the operating positions, the communication link including a coaxial cable and a frame grabber port. Is effective.

The calibration means: a reference or reference sensor coordinate frame which is a coordinate frame of at least two imaging devices; a combination of output signals from the at least two imaging devices, the first light source in the sensor coordinate frame Preferably, the first light position of the first light position is coupled to the first coordinate position; and the first light position is positioned on the first part within the sensor coordinate frame.

[0017]   Conveniently, the means for mounting the second part is a drill mount.

[0018]   Advantageously, the second part is a drill.

It is preferred to include two said imaging devices substantially equidistant about the central axis of the drill mount.

Conveniently, the means for mounting the second component is a jig having a plurality of suction devices removably attachable thereto and operatively associated with the means for pneumatic action.

Advantageously, there are four said imaging devices which are substantially equally spaced about the central axis of the jig.

According to yet another aspect of the present invention, a first object for work, inspection, or movement.
A method of determining the position and orientation of a component of the first component; the first component being held by or remote from the device: active light source or illuminable on at least two imaging devices Multiple first points including multiple reflection points or both
A distribution of light projected or reflected from the light source of the light source; sending a signal from each of the at least two imaging devices to the processor to process the signal; and from the processed signal. A method is provided that includes calibrating the light distribution using a calibrating means to determine the position and orientation of the first part.

A calibration of the light distribution is: at least identifying each active light source including a plurality of first light sources and / or irradiable reflection points from the output signals from the at least two imaging devices, and at least Defining a first position in a sensor coordinate frame that is a coordinate frame of two imaging devices; combining each of the first positions to generate a plurality of first positions in the sensor coordinate frame; And a plurality of first positions
Preferably to determine the position and orientation of the first part within the sensor coordinate frame by converting to a position related to the part.

Reference will now be made, by way of example, to the accompanying drawings to provide a better understanding of the present invention and to show how it may be practiced.

BEST MODE FOR CARRYING OUT THE INVENTION As shown in FIGS. 1 to 3, an apparatus for measuring the position and orientation of a first part to be worked, inspected, or moved according to the present invention has a non-contact, accurate It is intended to be used in situations where a measurement is required and the work of the device overlaps the work of an additional component used to control the position and orientation of the first part, such as a robot. The device is thus suitable for use with various robots and mechanical tools.

FIG. 1 of the accompanying drawings shows an apparatus for measuring the position and orientation of a first part to be worked, inspected or moved according to a first embodiment of the present invention.
Components 1 are either held by the device or separate from the device: an end effector 2; each attachable to the end effector 2 and each mounted on the first face 4 of the first part 1. At least two imaging devices 3 configurable to image
a, 3b; and a plurality of first light sources 5. The first light source 5 comprises an active light source and / or an illuminatable reflection point and can be positioned on said first part 1, whereby a first surface 4 of the first part 1 is provided. When positioned above, a distribution of light is produced in at least two imaging devices 3a, 3b as the light is projected or reflected from each of the first light sources 5. Imaging device 3a, 3
Each of the b's is operable to output a signal 6a, 6b indicative of the distribution of the light, and a processor 7 is provided to receive and process the output signals 6a, 6b, the processor 7 having the calibration shown in FIG. It operates in connection with means 12. The calibration means 12 calibrates the output signals 6a, 6b processed by the processor 7 to determine the position and orientation of the first part 1.

As further shown in FIG. 1, the end effector 2 comprises means 2a for mounting the second part 8 thereon, the means 2a for mounting the second part being a drill mount 13. The second part 8 is a drill.

The apparatus comprises at least two light sources 9a, 9b, each light source 9a, 9b being associated with a respective imaging device 3a, 3b. The plurality of first light sources 5 in the embodiment of FIG. 1 are a plurality of reflective targets, each of which can be located on the first part 1, each of which is made from a retroreflective material and the second light source of The light projected by each of 9a, 9b is reflected back from it in the exact direction of the incident ray. To derive a solution that does not degrade the position and orientation of the first part 1, at least 6
It is possible to place on the first part 1 two such targets, each of which is not a planar body and each of which is non-linearly spaced from each other.
Instead, the target position is known in relation to the first position, a minimum of three is required.

Each of the at least two imaging devices 3 a, 3 b is a metrology sensor operable to produce a digitizable image, such that the light projected or reflected from each of the first light sources 5 is on a dark background. Is preferably re-generated as an image of white pixels, which define the two-dimensional spatial position of the first light source 5 in each of the imaging devices 3a, 3b. These images are communicated as output signals 6a, 6b to the processor 7 through the communication link 11, preferably coaxial cables or twisted wire pairs, through the frame grabber ports 11a, 11b. The output signals 6a and 6b are the International Radio Consultative Committee (CCIR).
Video data is included in a format such as e).

As shown in the block diagram of FIG. 3, the calibration means 12 typically includes a reference or reference sensor coordinate frame 12a, which is determined by standard three-dimensional triangulation techniques.
To operate on this data, the reference sensor coordinate frame 12a defines a single reference coordinate frame corresponding to at least two imaging devices 3a, 3b. The calibrating means 12 further comprises combining means for combining the output signals 6a, 6b in the form of bitmap images corresponding to at least two imaging devices 3a, 3b.
12b, the first light position 12c of the first light source 5 in the sensor coordinate frame 12a
, And a transformation means 12d for locating a first light position 12c on the first part 1 in the sensor coordinate frame 12a.

FIG. 2 of the accompanying drawings is generally similar to the apparatus of FIGS. 1 and 3 and is a second implementation of the invention for measuring the position and orientation of a first part to be worked, inspected or moved. 1 shows a device according to the embodiment, like parts being designated by like reference numerals and without further detailed description. As shown in FIG. 2, the end effector 2 shows means 2a for mounting the second component 8 thereon, and the means 2a for mounting the second component is
A jig 14 having a plurality of suction devices 15 removably attachable thereto,
The second part 8 is the first part 1. Alternatively, the means 2a may be provided by magnetic or mechanical gripping means. In this embodiment, as shown in FIG.
There are four imaging devices 3a, 3b, 3c, 3d, which are the central axis 14 of the jig 14.
Substantially equidistant with respect to a.

The device of the invention, as mentioned above, is operable to carry out the method of the invention to measure the position and orientation of the first part 1 to be worked, inspected or moved, This method is equally applicable to both embodiments. For the sake of clarity, reference has been made with reference to the first embodiment shown in FIG. 1, for at least two imaging devices 3a, 3b emanating from a plurality of first light sources and projected or reflected. Imaging the light distribution of the light, and sending signals 6a, 6b indicative of the light distribution from each of the imaging devices 3a, 3b to the processor 7. These signals 6a, 6b are analog signals digitized by a frame grabber in the processor 7 and stored in memory as bitmaps 16a, 16b for further processing.

Another process is the first process from the bitmaps 16a, 16b corresponding to the output signals 6a, 6b.
It involves identifying each of the light sources 5 and defining their position within the sensor coordinate frame 12a substantially shown in FIG. This therefore requires the determination of the sensor coordinate frame 12a, which sensor coordinate frame 12a should preferably define a single coordinate frame for reference, to which the measured values taken by any of the imaging devices 3a, 3b Can be related. This is typically done offline and there are several ways known to those skilled in the art to achieve this. One such method is
Taking measurements from a number of imaging positions for active light sources located at pre-specified positions in a known coordinate frame, and imaging devices 3a, 3
It involves mathematically optimizing the measurements to derive a transformation that describes the relationship between each of b. Once the coordinate frame 12a has been derived, it is used, as described in the present invention, to transform subsequent measurements of an active light source placed in an unknown position relative to the imaging device 3a, 3b. To do.

After performing this alternative process, the distribution of light stored in the bitmaps 16a, 16b is calibrated to determine the position and orientation of the first component. Bitmap 16a, 16
b is stored in memory and comprises a two-dimensional array of pixel light intensity values corresponding to the sampling of the output signals 6a, 6b, each analyzed by the processor 7 in a two-dimensional space and a plurality of sensor coordinate systems 12a. Bright dot (bright spot) 17a
, 17b are positioned. These bright dots 17a and 17b are the image forming device 3a.
3b is assumed to correspond to the first light source 5 recorded.

The calibration is performed by the processor 7 and uses the characteristics of the focal length of each imaging device 3a, 3b to perform a calculation that projects a ray from each of the plurality of bright dots 17a, 17b into a three-dimensional space. . In this manner, each of the plurality of dots 17a, 17b has a corresponding line 18a, 18b projecting from it, and the intersection of each of these lines defines a plurality of first locations 12c within the sensor coordinate frame 12a.

Once the first position 12c has been derived, the first position 12c requires a conversion to a position 12d in the first part 1 to determine the position and orientation of the first part in the sensor coordinate frame 12a. Establish. This is done according to one of several techniques known to the person skilled in the art, for example at least three of the first light sources 5 at the data positions specified in the corresponding CAD model of the first part 1. Can be achieved by positioning The position 12d of the remaining light source 5 is easily calibrated to the first part.

[Brief description of drawings]

FIG. 1 is a first object to be operated, inspected, or moved according to a first embodiment of the present invention.
Schematic perspective view of an apparatus for measuring the position and orientation of parts of FIG.

FIG. 2 shows a first object to be operated, inspected, or moved according to a second embodiment of the present invention.
Schematic perspective view of an apparatus for measuring the position and orientation of parts of FIG.

[Figure 3]   The schematic block diagram of the 1st and 2nd apparatus which shows a calibration means.

─────────────────────────────────────────────────── ─── Continued front page    (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, I T, LU, MC, NL, PT, SE), OA (BF, BJ , CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, K E, LS, MW, MZ, SD, SL, SZ, TZ, UG , ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AG, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, C H, CN, CR, CU, CZ, DE, DK, DM, DZ , EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, JP, KE, K G, KP, KR, KZ, LC, LK, LR, LS, LT , LU, LV, MA, MD, MG, MK, MN, MW, MX, MZ, NO, NZ, PL, PT, RO, RU, S D, SE, SG, SI, SK, SL, TJ, TM, TR , TT, TZ, UA, UG, US, UZ, VN, YU, ZA, ZW F term (reference) 2F065 AA04 AA37 FF41 GG15 JJ03                       JJ26 LL16 QQ00 QQ03                 3C007 AS12 KS03 KS04 KT03 KT05                       KT11 LT06 [Continued summary] A processor that receives and processes the output signal that indicates the distribution of light from the Operatively related to the processor (7); and the processor (7) And the distribution of light processed by the processor (7) The output signal (6a, 6b) indicating A calibration means (12) for determining the position and orientation of (1) Device containing.

Claims (15)

[Claims] 1. A device for measuring the position and orientation of a first part to be worked, inspected, or moved, the first part being held by the device or separated from the device: an end. Effector; at least two imaging devices, each of which is connectable to an end effector and each configurable to image on a first side of a first part
One imaging device; a plurality of first light sources, comprising an active light source and / or an illuminatable reflection point, or both, which can be positioned on said first part, whereby
When light is projected or reflected from each of the first light sources when positioned on the first surface of the first component, a distribution of light is generated in each of the at least two imaging devices, at least A plurality of first light sources, each of the two imaging devices operable to output a signal indicative of the distribution of light received by each imaging device; a distribution of light from each of the imaging devices A processor for receiving and processing the indicated output signal; and calibration means operatively associated with the processor for calibrating the output signal indicative of the distribution of the light processed by the processor and for determining the position and orientation of the first component. A device that includes. 2. The device of claim 1, wherein the end effector includes means for mounting the second component thereon. 3. The apparatus of claim 1 or 2, wherein each of the at least two imaging devices is a metrology sensor operable to produce a digitizable image. 4. At least two second light sources, each associated with each imaging device, a plurality of first light sources being a plurality of reflective targets, each positionable on a first part. The device according to claim 3, wherein 5. The apparatus of claim 4, wherein each of the plurality of reflective targets is made of retroreflective material. 6. The apparatus of claim 5, wherein the plurality of reflective targets includes at least six reflective targets, each non-planar and non-linearly spaced from one another. 7. A communication link between the imaging device and the processor for transmitting an output signal indicative of light distribution at each of the operating positions, the communication link including a coaxial cable and a frame grabber port. 7. The device of claim 6 including. 8. The calibration means comprises: a reference sensor coordinate frame which is a coordinate frame of at least two image forming devices; combining output signals from at least two image forming devices to the first light source within the sensor coordinate frame. 8. The apparatus of claim 7 including coupling means for defining a first light position of the first light position; and transformation means for positioning the position of the first light on the first component within the sensor coordinate frame. 9. The apparatus of claim 8 wherein the means for mounting the second component is a drill mount. 10. The apparatus of claim 9, wherein the second component is a drill. 11. The apparatus of claim 10 including two said imaging devices substantially equidistant about a drill mount central axis. 12. The apparatus of claim 8 wherein the means for mounting the second component is a jig having a plurality of suction devices removably attachable thereto and operatively associated with the pneumatic means. 13. The apparatus of claim 12 having four said imaging devices substantially equidistant with respect to the center axis of the jig. 14. A method for measuring the position and orientation of a first part to be worked, inspected, or moved, said first part being held by or remote from the device: at least Imaging the distribution of light projected or reflected from a plurality of first light sources, including active light sources and / or illuminatable reflection points, on both imaging devices; at least two imaging devices Sending a signal from each of the devices to the processor indicating the distribution of light and processing the signal; and calibrating the distribution of light from the processed signal using calibration means to determine the position of the first component and A method comprising determining orientation. 15. A calibration of the light distribution comprises: distinguishing from each output signal from at least two imaging devices, each active light source including a plurality of first light sources and / or illuminatable reflection points. Determining a first position in a sensor coordinate frame that is a coordinate frame of at least two imaging devices; combining each of the first positions to generate a plurality of first positions in the sensor coordinate frame 15. The method of claim 14, including the steps of: converting a plurality of first positions into positions associated with the first part to define a position and orientation of the first part within the sensor coordinate frame.