Device and method for measuring the relative spatial position of two objects

Translation of description of equivalent WO 2007124902 A2

p0001Apparatus and method for assessing the relative spatial position of two objects

p0002The invention relates to a method and associated apparatus for the quantitative assessment of spatial positioning and orientation of two machines or machine parts relative to one another, such as shafts, machine tool spindles, workpieces or other physical objects. The invention is also adapted to measure the alignment or the alignment of two mutually aligned cylindrical objects quantitatively or to judge, for example, on pipes or pipelines. Furthermore, the device is suitable to serve as a sensor in a coordinate or a sensing robot. Moreover, the invention is useful to find a measuring device for measuring tasks in construction or civil engineering, especially during tunnel application.

p0003Methods and devices of a similar nature have been successful in assessing the spatial positioning and orientation of two machines or machine parts relative to one another in use for several years and have been characterized that a tremendous amount of work has been saved by its use.

p0004A corresponding generic apparatus is known from DE 10117390, which is referred to further in this regard prior art.

p0005In the cited document shows how the aligned position of two machine parts using a beam-generating light source checked, measured and can be assessed.

p0006The known devices and methods often see precision parts and - components before, sometimes costly optical components, and thus enable precise and reliable measurements.

p0007The object of the invention, the device side to improve the known methods and devices such that the accuracy of such a device can be increased further still, at the same time significantly increasing its measuring range, both in the lateral (distance moderate) and transverse (transverse) dimension , This is the use of a device according to the invention even in such Applications possible where previous measuring systems were the technically feasible encountered in terms of resolution, linearity or size of the measurement range already at the limits.

p0008With a device according to the invention can be checked or measured quantitatively:

p0009- Translational offset between two articles to be measured according to two directions of space, for example, horizontal and vertical

p0010- Angle excessive offset between two articles to be measured, by up to three angular coordinates in space, such as azimuth and elevation and roll angle

p0011The apparatus may therefore very well in a metrological coordinate measuring apparatus, for example DE 200 02 150 are used.

p0012To solve the above problem is provided:

p0013- A, so that the cross section of the emitted light beam having a repeatedly fanned light beam, in particular a double-surface laser light beam emitting means to a crosshair (eng, crosshair), a star or a generalized, irregular shape of a cross or a star

p0014- At least two, preferably at least three or more linear optoelectronic sensor arrays or position sensitive diodes (PSDs) for directly or indirectly determining incidence points of the widened in two or more planes light beam.

p0015An associated measuring method according to the invention provides the use of the measuring device according to the invention in one or more steps.

p0016The use of the inventive measuring method or device according to the invention is according to the invention not only advantageous to measure the displacement of machine parts such as shafts or pipes, but can also be carried out advantageously in metrological devices such Meßrobotern or coordinate measuring machines.

p0017In order to generate a multiply fanned and thus spread in, for example, two or more levels of the light beam, a diffraction grating, for example, is provided in the form of a transparent point grid preferred. Alternatively, a instead Hologram or a microlens array is provided. The diffraction grating, the hologram or microlens array are preferably transmissive (ie proportionally translucent) and are used with advantage in the beam path of a conventional laser. They thus produce the desired beam cross-sectional shape. It can also be used in so in a laser beam, said optical elements but that also their reflective properties become effective and be used.

p0018According to the invention, a conventional two-dimensionally readable optoelectronic sensor is functionally replaced by an array of either three (on side lines of a triangle arranged to each other) linear opto-electronic arrays in CCD or CMOS technology, or an array of, preferably four, if desired, further such linear arrays (even line sensors or line sensors called).

p0019Compared to the previous state of the art has such an arrangement the following significant advantages:

p0020- Enlargement of the measuring range for determining a laser impingement or its equivalent to more than 35 mm, compared to previously typ approx. 10 - 20 mm

p0021- Increasing the optical resolution at 1: 100,000 or more, compared to before about 1: 10,000 (when using averaging method)

p0022Color discrimination, thus further suppressing possibility of extraneous light

p0023- Ie improved highly precise linearity of the sensor

p0024- Ability to record another Drehwinkelkoordinate (ie roll angle)

p0025- Very high light sensitivity

p0026- Very rapid deployment of digitized measurement data possible

p0027- Intensive luminance providable by using laser light sources of up to 5 mW or more at non-coherent or more colored light sources

p0028- Drastic cost reduction With the invention presented the measurement results obtained can be used in a subsequent step and by an associated method to document the position and / or angular position of faulty relatively aligned objects either with great accuracy, or to correct with the highest precision. - The use of the invention as a measuring device in a coordinate or sensing robot is providing great benefits, since the relocation of specimens, workpieces can be so measured relative to a measuring table above with great precision and registered. Similarly, the use of the invention as a measuring device for surveying work in construction or civil engineering, specially in tunnel construction, advantageously possible.

p0029According to the invention, it is useful if in addition to the light or laser light-generating device and the light receiving device, additional auxiliary devices are available, such as in the form of additional inclinometer, especially electronic inclinometers, or visually Inspectable Levels.

p0030The invention is explained below with reference to the drawing. It shows:

p0031FIG. 1 is a perspective schematic lateral view of an inventive device with a crosshair-shaped light or laser beam emitting unit and a light receiving unit which are mounted on the shaft ends

p0032FIG. 2 is a schematic plan view the operation of the light-receiving unit with four line sensors (alternatively PSDs)

p0033Fig. 3 in a schematic plan view the operation of the light-receiving unit with three line sensors or PSDs

p0034Fig. 4 is a schematic of an embodiment of the invention with a plurality of

p0035Line sensors or PSDs whose effective lobby is increased by overlapping arrangement Fig. 5 shows another scheme of an embodiment of the invention with a

p0036Plurality of line sensors or PSDs, which are arranged approximately annularly

p0037Fig. 6 is a schematic plan view of a further embodiment of the

p0038Invention with only two linear opto-electronic sensors and an attached near light or laser transmitter for generating multiple-area light or laser beams

p0039similar to FIG. 7 is another schematic plan view of Fig. 6, each having non-orthogonally oriented line sensors or PSDs

p0040As shown in FIG. 1, schematically, a metrological system according to the invention in two separate housings 30, 130 may be housed. There are retaining or clamping devices 22, 122 is provided so that an application to shaft ends 10, 110 of machinery in a conventional manner and technique is possible.

p0041Within the housing 30 there is a device for generating two-oriented forward laser light planes, which are preferably oriented perpendicular to each other. As already mentioned, the generation of this particular laser light by means of diffractive grating, a hologram or a microlens array can be made.

p0042Thus, the device connected to the housing 130 provides a reception apparatus specifically designed for an incident laser or light beam having substantially crosshair-shaped cross-section. As the receiving elements, the line sensors are used (linear array) or position-sensitive detectors (PSDs) 42, 43, 52 and 53, which are arranged approximately on the sides of a square. In the center of the square of the origin of a coordinate system can be defined. The electronic circuitry and readout of optoelectronic modules, which are delivered as line sensors eg from Sony, is done in a conventional manner, for example by a superordinate computer (not shown). Device 130 is in its electro-optical properties to a conventional rectangular electro-optical sensor, which is to detect the incidence of a simple laser beam superior in several respects. This concerns in particular the size of the measurement range, the sensitivity and linearity. As shown in FIG. 1, instead of registering a point of impingement of a simple laser beam (with the cross section of a circle diameter of about 1 to 5 mm) at the point Z on a position sensitive diode (PSD) or a sheet-like pixel-oriented CMOS or CCD inch type image now the crosshair-shaped laser beam in an innovative manner in conjunction with a plurality, ie at least two, but preferably used three or four line sensors to an authoritative Auftreffzentrum Z to define. It can be seen that the cross section of the yarn cross-shaped light or laser beam is suitably defined by lines of at least 20 mm in length. The effective coordinates of Auftreffzentrums the crosshair-shaped laser beam so calculated by averaging, ie using illuminated by my light beam line sensors 42, 43 delivered abscissa and the mean of the ordinate values ​​delivered by the illuminated by light beam line sensors 52, 53rd In contrast to the previously known art with two-dimensionally readable Positionssensierenden diodes (PSD), the rotational position of the light beam (roll angle) can now be determined relative to the receiving device 130 easily, as represented symbolically in FIG. 2. - The existing in the housing 130 device can be added optionally, in principle, by its own light or laser transmitter that emits light in the vicinity of the center Z. Such a combined device can then, on the basis of prior art, are used in pairs for envisaged Meßvorhaben, to further increase the accuracy and to detect not only of parallel misalignment, but also of angular misalignment between the articles to be measured. Such a device with additional light or laser transmitter can also be used individually if it cooperates with its opposite in the direction of the light beam to be emitted reflector. Such a reflector may be either a plane mirror or consist of a reflecting prism.

p0043In FIG. 2 it is shown how the proportional plane 40 of the light or laser beam on the line sensors 42, 43 is incident, and thence to color, intensity and point of incidence by means can be registered methods known per se not shown (downstream electronic evaluation circuits or computer, see plug-in device 57). It also shows how the proportional plane 50 of the light or laser beam is incident on the line sensors 52, 53 and may be registered in the color, intensity and incidence. The said commercial pixel-oriented line sensors have a resolution of better than 3 * 10000 pixels, at a Pixel lattice constant of about 3 micrometers. course line sensors can be provided at a lower pixel count for high-low operating devices. If necessary, linear PSDs may instead be provided. The center Z of interest is calculated as mentioned supplied from the average values ​​of the detected ie from the line sensors or PSDs abscissa and ordinate of the incident light beam from crosshair-shaped cross-section.

p0044Transmitter and receiver can also be mounted on the shaft ends 10, 110 that the light or laser beam 40, 50 is practically parallel to the axis radiated to shaft end 10th A caring torsional or roll angle of said shaft ends is then calculated from the difference values ​​of the abscissa of the measurements supplied by the line sensors and the corresponding ordinate and the distance of the line sensors from their common center. This torsional or roll angle may be determined in the dimensioning shown relatively accurate (order of about 5 microrad).

p0045According to another embodiment of the invention an indirect picture of the light beam can by means of a focusing screen, on which the light beam coincides with fadenkreuzartigem cross section, and a projecting optical system which projects the image on the ground glass line sensors, are made. In this way it is possible to the desired range to either increase (eg 300 - 500 mm), or if necessary to reduce (eg 5 -. 10 mm).

p0046To reduce costs, it is according to the invention and as shown in Fig. 3 also possible to provide only 3 arranged on a circle line sensors. This then falls on a specially fanned light beam, which is characterized by three individual planes 40, 50 'and 60th These levels thus have an angle of eg 60 ° against each other. Calculating the position of a center Z of this fanned-out light beam is also done at a relatively formed by the line sensors center of symmetry using known methods of geometry and algebra. Once the dispersed light beam illuminates only central elements of the line sensors, can, as long as no additional angle excessive misalignment is present, are closed on a correct alignment between the articles to be measured. As shown in Fig. 4, the measuring range of an arrangement according to Fig. 3 can be increased even without optical means. As shown, in addition to the line sensors 42, 52 'and 53' further, in each case in parallel with these arranged line sensors 422, 423; 521, 522; 531, 532 available. These additional line sensors are so arranged in a radially outer region. The illustrated overlapping arrangement of the line sensors so a further compared to the prior art significantly extended measurement range is provided. There are effective measurement areas of 100 mm x 100 mm and more presentable. If with strong displacement or rotation of the light beam-combination consisting of light beams 40, 50 ', 60 can be expected relative to the line sensors, can as shown more line sensors 421, 523, 533 are provided. In this way, an additionally enlarged measuring range is provided.

p0047As shown in Fig. 5, an, in principle, any large measuring range for detecting the position of a multiply fanned light beam can be represented relatively to a receiving device by a plurality of line sensors (42, 42 ', 52, 52', 43, 53 ', 53, 53 ') are arranged in ring-shaped, and optionally also an overlapping manner on a suitable measurement surface. It is understood that in a harsh environment is a suitable protective housing with respective apertures for the illustrated line sensors useful. As shown in Figure 5. Schematically (ie without the line sensors 42 to 53 nachzuschaltende Electronics), a very large measurement area can be created in one or in a comparable arrangement. With this, the position and / or rotational position can be measured very precisely a parallel displaced and / or about its longitudinal axis rotated light beam having a plurality of proportional light surfaces or planes (40, 50). For this purpose, as in the other described cases, the point of incidence of the light beam on the exposed line sensors electronically determined. Based on such determined measurement data, it is then possible using standard mathematical and geometrical methods to determine the location of the center Z of the light beam relative to the line sensors a coordinate system assigned high to highest precision.

p0048An even more cost-effective embodiment of the invention with only two linear optoelectronic sensors is shown in Fig. 6. However, these works not as accurate as a remotely comparable device of FIG. 1 and 2, since no averaging can be carried out, it is also not directly possible to detect a torsional or torsion between the articles to be measured. - In addition to the line sensors or PSDs 42 ', 52', which are placed in or on a housing 130 'that their longitudinal directions are mutually orthogonal, 31 may be optionally provided a light or laser transmitter. As explained with the previous figures, it is also in this case so that the two line sensors or PSDs are intended to detect the position of impingement of a multiply fanned light or laser beam on these sensors, and as an electronic signal to a superordinate electronics (55 and downstream electronics, not shown) pass it. The linear optoelectronic sensors 42 'and 52', the electronics and, if the light or laser transmitter 31 can be powered by a battery, which are housed in a battery case 56th If necessary, can be a wireless data transmission (not shown) may be provided, which enables data communication with external computers, an electronic, portable telephones, so-called PDA devices. As can be seen, a parallel displacement of the housing 130 'with respect to a light incident on this multiple-area light or laser beam already with the two sensors 42' 'can be recorded and the 52nd In the illustrated case 50 are the flat light or laser beams 40, orthogonal to each other, ie, those associated surface normals are perpendicular. The in FIG. 6 (and also in Fig. 7) shown embodiment is adapted to operate in a paired combination, ie in conjunction with a virtually completely identical, frontally opposed copy of such a device. The holding devices 22 'meet comparable mounting structures according to the prior art and serve the housing 130 to span as a shaft end (see. FIG. 1, reference numerals 10, 110 and 20, 120).

p0049The further development of the invention according to FIG. 7 provides, in contrast to FIGS. 3, 4 or 5 is also only two linear opto-electronic sensors before. In this case, the longitudinal axes of the sensors 52 'and 53', however, arranged for example at an angle of 60 ° to each other, so that a gedrungenere design is made possible. Otherwise, the operation is substantially that of FIG. 6 shown. However, the sensors shown 50 ', 52' particularly are adapted to receive a light or laser beam from at least two individual surfaces 50 ', 60 is assembled. The normals of these individual surfaces have in the example shown an angle of 60 ° to each other, so that the angle alpha shown a value of 120 ° takes. - It can optionally an additional third Light surface (40) are provided, if advised for reasons of production appears, even if this light area comes into operation only at extreme angles of rotation between the articles to be measured.

p0050The embodiment of FIG. 7 with the intended optional private light or laser transmitter 31 is specially designed to work in a paired combination with a second, similarly acting device of this kind. In this case, it is then provided that this same effect devices frontal face. In this way, then, alternately, the light or laser transmitter 31 of a device the opposite line sensors 50 ', 52' light. In this way, similar to devices of the prior art, in a reliable manner both a parallel displacement (translational displacement) and an angular displacement (of angular misalignment) between the objects to be measured according to two associated coordinates are detected quantitatively.

p0051Instead of the FIG. 6 and 7 provided for mounting of a housing 130 ', 130' to eg waves can be provided other installation or clamping devices, which are designed, for example, that the figure axis of the or the light or laser transmitter with at least one symmetry axis of the to be measured objects nearly coincident.