CN1069120A

CN1069120A - " palindrome " code system photoelectric coded disk and method for designing thereof

Info

Publication number: CN1069120A
Application number: CN 91108127
Authority: CN
Inventors: 顾震雷
Original assignee: Nanjing Astronomical Instruments Research Center of CAS
Current assignee: Nanjing Astronomical Instruments Co Ltd
Priority date: 1991-07-29
Filing date: 1991-07-29
Publication date: 1993-02-17

Abstract

The invention provides and a kind ofly be used for doing the angle absolute measurement and at the palindrome encoding method of robot control system(RCS) as the photoelectric coded disk of angle speed feedback element.With the code-disc that this method is made, how high no matter reading accuracy requires, code channel number is together, and key is to determine code bit number n by known reading accuracy, code-disc is divided into subregions such as n, designs the base region sign indicating number by the permutation and combination principle again, determines whole code-disc again.The plain logarithm of black and white is required by reading and code bit number is determined, compares with tradition " Gray " system code-disc, and code channel number only is together, so for making high precision, the miniaturization code-disc has been created condition.If this kind sign indicating number is launched, also can constitute linear encoder.

Description

" palindrome " code system photoelectric coded disk and method for designing thereof

The invention belongs to field of photoelectric technology, relate to photoelectric encoder, particularly the coding method of absolute type reading disk light beam encoder code-disc.

At present, utilize the circle grating to make the absolute type reading disk light beam encoder of measurement of angle both at home and abroad, " Gray " sign indicating number of British Gray's invention is all adopted in the code channel design of its grating encoder, continues to use so far four, 50 years.This kind sign indicating number is along with improving constantly that reading accuracy requires, and the code channel number on the code-disc also must increase thereupon, thereby the increase of code-disc diameter, and has brought making difficulty and the inevitable error of scribing the multiple tracks sign indicating number on code-disc to increase.

The objective of the invention is to design a kind of new code channel structure, only design one yard, just can express any reading accuracy, thereby it is simple that code-disc is made, and realizes high precision and miniaturization easily.Coding method-title " palindrome " sign indicating number code system that this kind is novel.

Key of the present invention is: only be provided with together on disk by some annular code channels that alternate black and white single element is constituted, the reading accuracy that provides according to the user requires (resolution), code channel is divided into the n equal portions, or claim the n bit code, can determine the plain logarithm M of the black and white that should get by readout resolutions e and code bit number n.On the circumferencial direction of disk, on the corresponding equal portions line position of n equal portions, n is set to photoemission-receiving trap, CD rotates a week, n to electrooptical device with regard to exportable corresponding to 2 ⁿThe difference of grade is formed signal, by decoding, just can read as 360 °/2 ⁿThe positional precision of grade.After figure place n determined, accordingly angle of elevation value was differentiated equivalent and has also just been determined, but the sign indicating number of this figure place also can be designed to differentiate the lower code structure of equivalent.For example, it is 0.1 ° that readout resolutions requires, and then can extrapolate at least to have 12 bit codes, when code-disc rotates a week, 12 photoelectric reading devices should be read 3600 worthwhile amounts in different angles, also are fine but 12 bit codes are designed to the lower code structure of readout resolutions.For guaranteeing that the worthwhile amount reading in angle on whole circumference has nothing in common with each other, simultaneously, when the worthwhile amount in two adjacent angles changes, the variation of one units sign indicating number reading only can only be arranged, so that the reading error minimum, when the design Huiwen code, can earlier code-disc along the circumferential direction be divided into and subregions such as the corresponding n of n bit code, whenever be divided into the 360/n degree, in subregions such as n, can design the Huiwen code reading of base region earlier, determine that then the Huiwen code of whole code-disc constitutes by the permutation and combination principle.Suppose that now it is 0.8 ° that readout resolutions requires, then disk rotates should 360/0.8=450 signal output a week, can extrapolate code bit number and be at least 9(2 ⁸=256,2 ⁹=512).

Nine palindrome code-discs that provide below in conjunction with accompanying drawing further specify the design procedure of Huiwen code.

Fig. 1 is nine Huiwen code disks.

Among the figure, an annular code channel by 25 pairs of alternate black and white single elements (printing opacity and light tight) formation, (black and white single element logarithm M can be calculated by known readout resolutions e and the code bit number n that is determined by e: M=360/2ne), code channel is divided into nine waits subregion, whenever be divided into 40 °.Nine pairs of equally spaced circumferencial directions that are distributed in of photoemission-receiving trap, one group of 9 figure place that exportable 9 different numbers constitute read sign indicating number.Design base region Huiwen code reading in nine districts earlier, method is as follows:

1, the reading that is located at the base is a ₁a ₂a ₃a ₄a ₅a ₆a ₇a ₈a ₉, when clockwise 360 °/9=40 °, arriving second district, reading is a ₂a ₃a ₄a ₅a ₆a ₇a ₈a ₉a ₁, then arriving the 3rd district in the time of clockwise again 40 °, reading becomes a ₃a ₄a ₅a ₆a ₇a ₈a ₉a ₁a ₂, go down so successively, as seen the sign indicating number of this group number can be formed 9 kinds and read sign indicating number turning over when week, and these the 9 kinds values of reading sign indicating number should have nothing in common with each other, and differ the value of 40 ° of angles on corresponding separately the circumference.Therefore, when having determined behind the coding of base the Huiwen code reading in other each district on the whole circumference, we have also just determined.

2, for guaranteeing that after turning over a week 9 numbers have nothing in common with each other, adopt the method for permutation and combination, calculate the sum that may list base Huiwen code reading in, be calculated as follows:

C ¹ ₉=9; N ¹ ₉=9/9=1。C ² ₉=36; N ² ₉=36/9=4。

C ³ ₉=84; N ⁴ ₉=84/9=9。C ⁴ ₉=126; N ⁴ ₉=126/9=14。

C ⁵ ₉=126; N ⁵ ₉=126/9=14。C ⁶ ₉=84; N ⁶ ₉=84/9=9。

C ⁷ ₉=36; N ⁷ ₉=36/9=4。C ⁸ ₉=9; N ⁸ ₉=9/9=1。

N=N ¹ ₉+N ² ₉+N ³ ₉+N ⁴ ₉+N ⁵ ₉+N ⁶ ₉+N ⁷ ₉+N ⁸ ₉=56

The explanation of above result of calculation, the base region by can 56 kinds of yardages of the highest design guarantee returning circle after, the 56 * 9=504 that an obtains yardage has nothing in common with each other.The reading of each yardage is shown as e=360 °/504.

3, list the basic comprising of each bar code, so that combination.

N ¹ ₉=1 N ² ₉=4 N ³ ₉=9 N ⁴ ₉=14

1 1111 111111111 11111111111111

0 1000 111111000 11111111111110

0 0100 100000111 11111000000001

0 0010 010000000 10000111100000

0 0001 001000100 01000100011101

0 0000 000100010 00100010010010

0 0000 000010001 00010001001001

0 0000 000001000 00001000100110

0 0000 000000000 00000000000000

N ⁵ ₉=14 N ⁶ ₉=9 N ⁷ ₉=4 N ⁸ ₉=1

11111111111111 111111111 1111 1

11111111110000 111111111 1111 1

11110000001110 111111000 1111 1

10001110001101 111000111 1110 1

01001001100011 100110110 1101 1

00100101011000 010101101 1011 1

00010010110111 001011011 0111 1

00000000000000 000000000 0000 0

4, obtain after the above basic code, just can begin to design the data readings in the Huiwen code base region, from N ⁸ ₉=1 beginning, both sides are respectively to N ⁷ ₉... N ¹ ₉Data combination is carried out in peek.Be noted that and face the variation that transformation of data must guarantee to have only a numerical digit mutually, operating error minimum like this, second, institute fetches data, can be according to actual needs or convenient reading.For example, in this paper example, the highest desirable 56 groups of numbers, but we only get 50 groups of numbers, like this, the expressed reading of each number is: e=360 °/50 * 9=0.8 °.

Three, design data good after, the first data and last digit also will match, its principle is: first of end position and the first second, second and the first the 3rd of position, end ... the 9th and the first first of position, end in these 9 groups of data, has only a pair of difference.This just meets the principle that matches.

5, designed data in the base region, combine as table:

00111111111111111111111111111111111111111111111110

00000001111111111111111111111111111111111111111111

11111100000000111000001111111111111111111111111100

01100000111111100000000000110000011111111111100000

00001111100000000011111100011111000000111111110000

00000000000110000000111110000001111110001111000111

00000111110000001110000111111100000111100110000000

00000000000011111111100000000111110011111100000000

00000000000000000000000000000000000000000000000000

First line number is engraved on first district, and second row is engraved on second district ... the 9th row is engraved on the 9th district, has so just finished the design of nine Huiwen codes, is made into chequered with black and white code channel.

" palindrome " code system optical disc that utilizes the present invention to provide, compare with " Gray " code system optical disc, disk diameter can significantly reduce, for example to can be made into diameter be ￠ 29mm or littler to the optical disc of 9 bit codes, in some occasion, as robot movable joint etc. locating just can to use in a large number, in addition owing to be one yard and therefore can segment to it.The black and white single element logarithm that " palindrome " sign indicating number constitutes code channel reduces greatly, and making the code channel simplicity of design also is the obvious advantage of palindrome code system, and the decoding scheme of Huiwen code is simple, and is inexpensive.In addition, this kind sign indicating number can also be launched to constitute linear encoder, have wide practical use.

Claims

1, a kind ofly is used for doing the angle absolute measurement and in " palindrome " the code system photoelectric coded disk and the method for designing thereof of robot control system(RCS) as angle speed feedback element, constitute by being engraved on the code channel of forming black and white unit alternate on the code-disc, it is characterized in that: code channel number is together, require to determine code bit number n according to reading accuracy, determine the plain logarithm of black and white again, concrete steps are:

A, along the circumferential direction code channel is divided into and subregions such as the corresponding n of code bit number, n is corresponding with the n mean line to photoemission-receiving trap;

B, in subregions such as n, design the Huiwen code reading of base region earlier by the permutation and combination principle;

C, calculate to determine that according to base Huiwen code reading the Huiwen code of whole code-disc constitutes;

D, scribe the annular code channel by base Huiwen code reading.