WO1987002450A1

WO1987002450A1 - Process and apparatus for transferring optically an angle between devices located at different points

Info

Publication number: WO1987002450A1
Application number: PCT/CH1986/000147
Authority: WO
Inventors: Bernhard F. GÄCHTER
Original assignee: Wild Heerbrugg Ag
Priority date: 1985-10-21
Filing date: 1986-10-20
Publication date: 1987-04-23
Also published as: JPS63501592A; CH670907A5; FR2588952A1; DE3600859A1; IL80358A0; EP0243385A1

Abstract

To transfer an angle between two devices located at different points using an optical instrument, a corresponding code pattern is transmitted in one direction from a device located at a first point to wards the other device located at the second point, the angular information of the first device being contained in the code. The image of the code pattern received is collected by the receiving device and transmitted to a signal-processing installation. The latter recognises shifts in the code pattern image by comparing with a reference code which is preset or stored. The angular value to be transferred is deduced by calculating the value of such shifts. The first device may be equipped with a reflector which reflects a coded signal towards the second device and during this operation includes the angular information in the signal. The code used can be a one or two-dimension space code or a time-staggered code; the angular information desired is obtained from the shift along the axis of the code and/or its intensity distribution on the receiver side.

Description

Method and device for optical angle transmission between devices at different locations

The invention relates to a method for transmitting angles between two devices at different locations, and a device for performing this method. The method and the device are used, for example, for the contactless transmission of an azimuth angle, as is e.g. in the field of geodesy, navigation, for coordinate transfer to machine tools and in similar applications.

Previously known methods and devices for contactless angle transmission are based on the principle of auto-reflection or auto-collimation, or on the principle of collimation. In the case of auto reflection, an observation telescope and a prism arranged at the second location are roughly aligned with one another by rotating or sliding until the telescope is located within a parallel strip which runs at right angles to the edge of the prism roof. The width of the parallel strip mentioned corresponds to the length of the roof edge of the prism. To transmit an azimuth related to the geographic north direction, the prism roof edge must be horizontal and it must have a fixed reference to the device reference of a device connected to the prism. A beam directed from the telescope to the prism is reflected in it so that it emerges again in the plane that is spanned by this beam itself and the prism edge, that is to say that the beam is deflected azimuthally and always returns vertically at the same angle as it enters the prism.

To transfer the azimuth from the prism to the telescope location, the telescope is rotated azimuthally until the image of the telescope or an observation theodolite, which is visible in the prism, is exactly symmetrical to the vertical line of one in the telescope or in the theodolite arranged cross hairs. If this is the case, the target axis is exactly perpendicular to the roof edge of the prism. However, this method, which is relatively simple for an operator, has the disadvantage that the measurement or transmission distance depends on the minimum target range of the telescope set to twice the target distance. For normal telescopes, this minimum target range does not extend to a distance of less than approx. 1 m. For such short distances, v / ie they have to be mastered, for example, when setting up or measuring workpieces on machine tools, this measurement method is therefore poorly or not suitable. Furthermore, because of the principle of auto reflection, the method is relatively imprecise, since the auto reflection condition is not particularly sharply defined for physical reasons. Although this method serves its purpose for rough measurements, it is not well suited for precision measurements.

In the principle of autocolliation, a telescope is focused on infinitely, with a crosshair being imaged on the collimator and a plane mirror in front of it, which is adjusted perpendicular to the optical axis. To transmit an azimuth angle, it is sufficient if the image of the crosshair is only coincident with the crosshair itself in one axis, for example only in the vertical line. Autocollimation is suitable for relative short target ranges. For the user, however, the condition is more difficult to set than the auto reflection. The principle of autocollination therefore places higher demands on the operator.

Finally, during the collision, two telescopes are collimated to one another, whereupon the reference to an external reference, e.g. to transfer angles related to the north direction from one device to the other.

All of the methods and devices described here require mechanical mutual alignment and possible displacement of the instruments or devices involved. There is therefore a considerable risk of malfunction in the event of contamination of at least one of the devices involved. Furthermore, the devices and thus the measuring method itself are susceptible to mechanical shocks, which is why such measuring methods are not very suitable for fast and reliable precision measurements in rough use, particularly when there is a risk of contamination. Furthermore, the accuracy of the setting can only be insufficiently maintained over a long period of time. Finally, the measurement process itself is time consuming. Automation would be very complex.

It is an object of the present invention to provide a method and a device with which a rapid and reliable angle transmission of the type described is possible without the risk of malfunctions or failures or incorrect transmissions. ''

This object is achieved according to the invention by the features defined in claims 1 and 7. The advantage of the inventive measures lies essentially in the high stability of the measuring accuracy, without the need for recalibration, and in the very fast and automatically executable measuring process itself. The measurement can be carried out in fractions of a second. Furthermore, it is no longer necessary to move any parts of the device or instrument mechanically, so that there is no fear of contamination or wear and tear.

The invention is explained in more detail below with the aid of preferred exemplary embodiments with the aid of the drawings.

Show it:

1 shows the schematic beam path of two devices to be aligned to the same azimuth,

_**

2 two telescopes, of which the optical axis of one is in the field of view of the other, for transmitting a direction defining an azimuth,

Fig. 3 shows a second embodiment with a

Reflection prism and a multiple collimator arrangement,

4 shows an arrangement according to the principles of FIG. 3, for the simultaneous transmission of two angles,

5 shows the beam path of a preferred exemplary embodiment, to explain the measuring process,

6A-C the code patterns drawn in the beam path of the measuring device and their images for different measurement configurations, and 7 shows an evaluation device for processing the signals supplied by the detector cells according to FIG. 5.

As the following detailed description using individual preferred devices shows, the principle of the angular transmission from a first device to a second one is based on the measurement of a deposit which occurs when a geometric code pattern is transmitted between a first and a second device. The storage registered in one of the two devices is e.g. detected by a group of detector cells and subjected to analytical signal processing. As a result of such signal processing, the direction information transmitted from the first to the second device, e.g. an angle information related to a common reference. As can be seen from the following detailed description, not only a single angle, for example an azimuth angle, can be transmitted according to the same principles, but with a slight adjustment of the device used, a second angle, e.g. in addition to the azimuth mentioned also an associated elevation angle.

The principle of the angle transmission used between two devices is first explained with reference to FIG. 1. A telescope 1 is aligned with the north direction N under an azimuth 'phi 1'. The same angle is to be transferred to a second device 2, which, however, is still under the azimuth 'phi 2' with respect to the north direction N. The second device can be connected to a directional device, for example a sharply focused directional antenna, such as is used for satellite radio. In addition to this mentioned straightening device, any other elements, for example adjustable parts of a machine tool, could also be used with the second device can be coupled or connected. According to FIG. 1, the misdirection of the second device is noticeable in an angular deviation 'delta' between the two optical axes of the devices.

For the transmission of angles which are related to a common reference, for example azimuth angles, it is sufficient to transfer the direction information of the first device to the second, that is, to use the angle 'delta ¹ as a measurement criterion for the angle transmission. To detect this angular deviation 'delta', two telescopes 1 and 2 are initially roughly aligned with one another, as shown in FIG. 2. To facilitate alignment, the telescope 1 is provided with an opening angle '2 alpha', while a second telescope belonging to the second device has a second opening angle '2 beta'.

Then, according to the invention, a linear code pattern 3, for example a bar code, is illuminated by a lamp 4 from the first telescope 1 and transmitted into the image plane of the second telescope 2. If the telescopes are not in alignment, ie if their optical axes are offset from one another by an angle 'delta', the image of the code pattern is shown laterally shifted by a certain amount in the second telescope. This shift is detected by a group of detector cells 3A, 33, 3C ... and processed in a signal processing device. The signal processing results in the degree of deviation of the code pattern image in the image plane of the second telescope from a predetermined reference value at which the devices are aligned with one another. The detector signal obtained thus indicates agreement or the extent of the deviation from a direction to be transmitted or from an angle to be transmitted. 3 shows a further exemplary embodiment of a device for angular transmission with a transmitting optic 10, a rotatable roof prism 11 and one or more receiving collimators 12A, 12B, 12C, each of the collimators having a group of detector cells 13, 14, 15 is seen. A linear code 16, for example a bar code, is transmitted from the transmitting optics 10 to the roof prism 11 with the aid of a light source 17 and is reflected by the latter into the receiving collimator device 12. Depending on the rotational position, that is to say the angular orientation of the roof prism 11, the image of the code pattern transmitted by the transmitting optics 10 appears in the receiving collimator 12 as a different image, namely with a lateral shift which corresponds to the change in the rotational position of the roof prism with respect to a reference position.

The signals detected by the collimator device 12 and the detector groups 13, 14, 15 are fed to a signal processing device, which will be discussed later. This signal processing device automatically detects the storage of the received bar code image from a reference position and detects it as an angular storage of the prism 11, or outputs it as a correction signal for tracking a device connected to the prism 11.

In a modification of this embodiment, according to FIG. 4, a device whose angular position is to be transmitted or detected is provided with a mirror 20. The mirror 20 is illuminated by an optical transmitter 21 which transmits the code of a two-dimensional code carrier. The image of the code pattern reflected by the mirror 20 is received by at least one collimator device 22. The collimator device 22 is a two-dimensionally arranged ordered group of detector cells 23. These individually scannable detector cells are used to detect a two-dimensional shift of the code pattern image from a reference position. With this two-dimensional displacement, changes in position of the mirror 20 are detected both in azimuthal and in a second angular dimension. The combined detection of the azimuth and the elevation of an object connected to the mirror 20 or its targeted tracking is therefore possible on the basis of measured deviations.

FIG. 5 shows a preferred exemplary embodiment based on the beam path in detail. The optics 40 of the transmission telescope define the transmission axis A, in the extension of which there is a code carrier 41 in the image plane which is provided with a bar code 42.

The bar code consists, for example, of a sequence of vertically running bars arranged next to one another, the bar width and the lateral spacing of the bars serving as direction-specific coding parameters. The combination of the bars of the code, which are arranged on a scale, contain information about the exact position along the "scale". Each area selected arbitrarily from the "scale" allows the precise determination of the area position on the "scale" if the code is known. In the example described, the code is applied to a transparent code carrier 41. The code carrier 41 is illuminated by a lamp 43 located behind it. The higher the demands on the measuring accuracy of the device, the finer the subdivision is to select the code on the code carriers 41, and the shorter the ^'Wellen¬ length of the illumination verv / emitted light source 43. For v / Eiteren improve the measurement accuracy contributes the quality of the transmission optics used and their large aperture. On the receiver side there is the receiving optics 45, the axis B of which is angularly offset from the transmitting axis A by the angle 'delta'. The code 42 of the code carrier 41 emitted by the transmitting optics 40 is imaged in a detector device 46, which is arranged in the image plane of the receiver optics 45. Corresponding to the angular offset 'delta', the code on the detector device 46 is also angularly offset, which is detected by the individual detector cells belonging to the detector group. The signals supplied by the detector cells are passed on to a signal processing device 50.

The position or the deviations of the code pattern on the transmitter side and of the code pattern image on the receiver side are shown for the various practical cases in FIGS. 6A to 6C. 6A, the transmitting and receiving sides are in perfect alignment. The code pattern image captured by the evaluation device is symmetrical about the center line Y and this state can be recognized by the coincidence of the zero line of the code image with the center line Y used as a reference.

In FIG. 6B, the axis of the transmitting optics is angularly offset from the axis of the receiving optics by the amount 'delta'. This state is indicated by the fact that the light intensity distribution of the code pattern in the image plane of the receiving optics is distributed symmetrically around the center line Y, but that the code itself appears offset to the side. The lateral offset of the code is given by the angular offset 'delta' multiplied by the focal length of the receiving optics. Finally, in FIG. 6C, the axis of the transmitting optics runs parallel to that of the receiving optics, but is laterally offset by a certain amount. This state is recognized in the receiver by the fact that the “intensity distribution of the code pattern is laterally offset, but the code itself is not offset.

For ^* automated signal evaluation, the signal processing device 50 contains an amplifier 51, a sample and hold circuit 52 and a downstream analog / digital converter 56, the output of which is led to a computer 53. A position sensor 57 is connected to the computer, with which a starting or reference position is set. The computer compares the values obtained from the analog / digital converter with the values stored in a reference memory 54 and displays the result on a display device 55. The display on the display device 55 can take place directly in angle values, that is to say indicate the angle 'delta' in degrees or degrees. However, the display can also be in coded or any other form. Furthermore, the coded signal can serve as a tracking signal for one of the two telescope devices in order to set them to a predetermined angular position.

Further details of the signal processing device 50 will not be dealt with here, since they are the subject of another proposal by the same applicant. (CH Pat. Request No. 6994/83).

If, in addition to a first angle, for example an azimuth angle, a further angle, for example an associated elevation angle, is to be transmitted or measured, instead of a one-dimensional code pattern, as described above, a two-dimensional code pattern ver / ends. This is evaluated by the receiving device according to the same principles as described for the one-dimensional code.

One- or two-dimensional spatial patterns were mentioned as code patterns. Instead, time-coded patterns can also be used, for which the transmitting and receiving devices are to be equipped with appropriate means for processing the signals staggered over time. In the context of the present invention, all such codes are understood by the term “direction-specific code pattern”.

Claims

PATENT CLAIM Ξ

1. method for transmitting an angle between zv / ei devices at different locations using optical instruments,

characterized in that a direction-specific code pattern is sent from a device at the first location to the second device at the second location, the code being embossed with the angle information of the first device,

that the image of the received code pattern is scanned in the receiving device and passed on to a signal evaluation device for evaluation,

that in the signal evaluation device, by comparison with predetermined or stored code reference values, shifts in the code pattern image from these reference values are recognized

and that the angular value to be transmitted is derived from the extent of such displacements by arithmetic operations.

2. The method according to claim 1, characterized in that the first device reflects a code signal received by a third device into the second device and thereby impresses its angular information on the code signal.

3. The method according to claim 1, characterized in that a one-dimensional spatial code is used as the code pattern, from whose displacement along the code axis and / or its intensity distribution on the receiver side, the desired angle information is obtained.

4. The method according to claim 1, characterized in that for the simultaneous transmission of two angle information, a two-dimensional code pattern is used / ended, one angle information being assigned to each dimension.

5. The method according to claim 1, characterized in that the scanning of the received code pattern is carried out via a sensor arrangement adapted to the dimension of the code pattern used, in parallel processing.

6. The method according to claim 1, characterized in that the scanning of the received code pattern is carried out in a serially operated scanning scanner.

7. Device for performing the method according to claim 1, characterized in that the first device (2) is provided with a reflector (11; 20), v / elcher is connected to those parts of the device whose angular position to the zv / eite device (1) is to be transmitted.

8. The device according to claim 7, characterized in that a third device for transmitting a code pattern is provided on the reflector of the first device (2) and that the second device is at least approximately in the reflection angle of the beam path for transmitting the code pattern.

9. The device according to claim 8, characterized in that the second and the third device are combined to form a structural unit.

10. The device according to claim 7, characterized in that a detector array is arranged in the image plane of the second device, the outputs of which are connected to a signal processing device (50) for deriving the transmitted angle values.