DE1242381B - Arrangement for converting the angular position of an encoder axis into a digital code formed from angular function values sin and / or cos - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

GOId

German class: 42 d - 2/50

Number: 1242 381

File number: S 67675IX b / 42 d

Filing date: March 22, 1960

Open date: June 15, 1967

The invention relates to an arrangement for converting the angular position of an encoder axis into angular information of the form sin α and cos a to be transmitted to a receiver.

The exact transfer of the axis position of an encoder axis to a receiver axis that z. B. at the radar image transmission is required to provide the primary and secondary images with respect to their cardinal points To be able to record consistently requires that the encoder axis be in every angular position an angle information clearly identifying the angular position can be formed, which for the Transmission to the receiving point and the exact setting of the receiving axis is suitable.

It is already known from measurement technology to encrypt measured instantaneous values Encryption discs to be used, which consist of a rotatable disc with concentric contact tracks exist for the coding process. Such an arrangement is used in a bridge circuit voltage encoding performed using a linear ring potentiometer, by encoding the angular position of the encoder disk, which is a function of tension.

In many cases, however, it is desirable, instead of linear information from the present one Forming the angular position of an encoder axis to a reference direction directly encoded information from to get the angular function values of the angular position of an axis. It is also already known under Use of a coding disk divided into several concentric circular rings, their circular rings one scanning element is assigned to each, a digital code from the angle function values of the axis position to build. The manufacture and scanning of such coding disks, the complicated geometric Having patterns presents difficulties which adversely affect accuracy affect the angle information.

The invention is based on the object of such arrangements for obtaining coded To improve angle information of angle function values while avoiding increased effort in such a way as to that particularly high demands on accuracy and low susceptibility to failure are met can be.

According to the invention this is achieved in that each circular ring of the coding disk in one with his Diameter increasing number of strips parallel to the diameter line of the same width with alternating, is divided into two distinguishable criteria consisting of labeling.

Arrangement for converting the angular position of a
Encoder axis into one of angle function values
sin and / or cos formed digital code

Applicant:

Siemens Aktiengesellschaft,
Berlin and Munich,
Munich 2, Wittelsbacherplatz 2

Named as inventor:

Dr.-Ing. Karl Ludwig Lenz, Munich-Solln

The design of the coding disk according to the invention, which directly supplies digitally coded angle function values from the angular position of an axis, represents represents a significant simplification for the manufacturing process compared to known coding disks. The accuracy with which angle information can be obtained depends on the number of concen ^ Irish circles, but at the same time the number of strips parallel to the diameter line with increasing diameter of the circular rings must increase. Lying on both sides of the diameter line and, based on the diameter line, corresponding strips of the circular rings must be have a different identification.

According to an advantageous further development of the inventive concept, the coding disk can be made from there are two halves of the same mirror image, but with the exception of a circular ring or a circular area, its halves are provided with such a distinguishable mark that they used to form a sign criterion ^ the can.

For the subjects of claims 2 to 6, only in connection with claim 1 Patent protection sought after.

The invention is explained in more detail using two exemplary embodiments in five figures.

In FIG. 1 are the angular functions sin α and cos «defined as segments in the unit circle shown. These lines are converted directly into a code in the present coding disk. First and foremost, a binary code is intended. However, other code forms can also be used realize.

709 590/159

In FIG. 2 is an encoder disk 1 with a number of interrogating elements 11, e.g. B. photocells, shown.

The coding can be carried out directly on the antenna by arranging the coding disk, which carries the code pattern and is photoelectrically scanned, on the antenna axis. The coding disk 1 is z. B. divided into five concentric circular rings 3 to 7, which enclose a circular area 8. Each circular ring is divided into an even number of parallel, equally wide strips which are alternately marked differently, as shown in FIG. 2 is shown for the circular rings 6 and 7 by white and hatched areas. The circular area 8 is divided into a hatched and a white half by the diameter line 2 of the coding disk. The individual strips of the circular rings are parallel to the diameter line 2, with such a marking that the corresponding strips of each circular ring located on the two halves of the coding disk have a different marking; z. B. the two mirror-inverted corresponding strips 9 and 10 of the circular ring 7 are marked differently. In the case of photoelectric scanning of the coding disk by photocells 11, one of which is assigned to the circular rings and the circular area 8, the different marking can consist in keeping the white stripes opaque and the hatched stripes transparent. However, the marking of the coding disk is also conceivable so that the scanning can take place electrically-static, magnetically-static, electromagnetic, galvanic or mechanical. In practice, the circular rings are expediently only made so wide that the resolution is ensured by the scanning elements, for. B. when using photocells 1 mm.

The division into translucent and opaque strips is an example of the implementation the angle function values into a binary code on which the formation of an angle information but is not limited. The number of strips into which each of the circular rings is divided increases Annulus to annulus by a factor of 2, and it is advisable to use the largest annulus on most common to subdivide. In the case of one shown in FIG. 2 indicated arrangement of the photocells 11 and sufficient fine division of the coding disc into circular rings, the code shows when going through all of them Angular values α shown in FIG. 3 function shown 1 + cos α. By simply subtracting 1 this gives the respective value of cos α. The one obtained from the angular position of the axis position Angle information can be given as a pulse code, e.g. B. in the radar image transmission during the video gap (Sawtooth return time). A high angular resolution radar image includes pro Video memory e.g. B. at least 500 pixels. The transmission channel required for this can therefore be used during the 10% video gap (sawtooth return time) Transfer 50 pixels, which is sufficient for the transfer of the angular impulses.

If the individual circular rings of the coding disk are queried one after the other during the video gap in order to to transmit the angle information directly, then there is a risk that the antenna in the interrogation time has continued to run for a small amount and because of the possible change in the labeling of a circular ring still to be queried, the angle information may be significantly falsified under certain circumstances will. It is therefore proposed to take all the information from the encoder disk at a time to take over in a memory to then with a corresponding number of code pulses to transmit one after the other. The angle information belonging to a video memory is no longer provided transferred, but an already outdated one. However, this error can be kept small enough will.

By moving the sensing elements (photocells) by an angle of 90 °, the corresponding sin values are obtained instead of the cos values. Since both the sin and cos values are to be obtained, the same coding disk can be used twice by using two query groups offset by 90 °. If the two query groups form an angle <C90 °, then values for sin <x and sin (α + β) or cos α and cos (<x + ß) can be obtained.

By forming the code pattern of the coding disk, as shown in FIG. 4, the function values of the absolute value of cos α can be obtained directly when passing through all angle values <x. The disk pattern is essentially designed so that it consists of mirror-image halves. Only the circular area enclosed by the circular rings is divided by the reflection axis into fields with different identifications (+ and -), by means of which from the absolute value of the function cos α, which is shown in FIG. 5 is shown, the function cos α can be derived itself. The division of the coding disk into circular rings and strips corresponds to that in FIG. 2 coding disk shown.

With the in F i g. 2 and 4 drawn coding disks with the division into parallel strips it is important that the interrogating elements (photocells) are at the correct distance from the axis of rotation sit so that they sit exactly below the center line of the respective ring, for the coding alone works exactly right. So that the adjustment of the query elements in the radial direction is not critical, it may be useful to use the dividing lines that separate the light and dark fields of a ring, to rotate so far that they run radially.

Claims (7)

Patent claims: 1. Arrangement for converting the angular position of an encoder axis into one of the angular function values sin and / or cos of the angular position of the encoder axis formed digital code, using one in several concentric circular rings subdivided coding disk, the circular rings of which are each assigned a scanning element, thereby characterized in that each circular ring (3 to 7) of the coding disk (1) in one with his The number of strips of the same width parallel to the diameter line (2) increases in diameter with alternating labeling consisting of two distinguishable criteria is. 2. Arrangement according to claim 1, characterized in that on both sides of the diameter line (2) Stripes lying horizontally and corresponding to one another in relation to the diameter line the circular rings (3 to 7) have a different identification. 3. Arrangement according to claim 1 or 2, characterized in that the coding disk (Fig. 4) consists of two halves that are mirror-inverted, but with the exception of a circular ring or a circular area, its halves with such a distinguishable marking are provided that they are used to form a sign criterion that changes along the diameter line can be used. 4. Arrangement according to one of the preceding claims, characterized in that the number the stripe with binary coding increases by a factor of 2 from annulus to annulus. 5. Arrangement according to one of the preceding claims, characterized in that the for Obtaining a binary coding required two criteria optically by scanning the in light and dark stripes subdivided circular rings by means of a photocell or with a correspondingly different type Formation of the coding disk by electrostatic, magnetic-static, electromagnetic, galvanic or mechanical scanning can be obtained. 6. Arrangement according to one of the preceding claims, characterized in that for extraction of sin and / or cos values with a coding disk two offset against each other or a group (s) of scanning elements offset with respect to a reference direction is arranged (are). Considered publications:
»Electronics«, 7th year, no. 7, July 1958, p. 201 to 207; »Transactions of the IRE, Issue J, 6, 1956, Pp. 161 to 167;
Sweet kind, “Notes on Analog-Digital Conversion Techniques ", Chapman & Hall Ltd., London 1958, P. 6 bis Considered older patents:
German Patent No. 1137 569. 1 sheet of drawings 709 590/159 6.67 © Bundesdruckerei Berlin