WO2008043231A1

WO2008043231A1 - A degraded pseudo-random rotating sensor

Info

Publication number: WO2008043231A1
Application number: PCT/CN2007/001864
Authority: WO
Inventors: Su Li
Original assignee: Su Li
Priority date: 2006-10-10
Filing date: 2007-06-13
Publication date: 2008-04-17
Also published as: CN1932451A; CN100425952C

Abstract

A degraded pseudo-random rotating sensor includes a code disk (2) which comprises a time code track (8) and a pseudo code track (9). The pseudo code track (9) is encoded by using a degraded binary pseudo-random sequence on an entire circle, that is: (1), a close loop is composed of a binary code sequence of m bits on an entire circle, representing that the entire circle is divided into m equal shares in which m is a positive integer; (2), a sequential binary code of n bits is selected as an angular position code, n≥ 4; (3),m<2n; (4), the angular position code which is composed of a sequential binary code of n bits selected arbitrarily is unique, and m of different angular position codes correspond one by one to the angular position of m equal shares which are equally divided on the entire circle.

Description

Degenerate pseudo-random rotation sensor

Technical field

The invention relates to a digital angle measuring photoelectric rotation sensor, also called a photoelectric shaft angle encoder. In particular, it relates to a photoelectric rotation sensor that applies a degenerate pseudo-random coding technique to perform angular position singularity processing on a code wheel circumference to provide position, direction, and velocity signals.

Background technique

Photoelectric rotation sensor (also known as photoelectric shaft angle encoder) is a digital angle measuring device that integrates light, machine and electricity. Due to its simple structure, high resolution and high precision, it has been widely used in precision angular position measurement, numerical control and digital display systems, and has become an ideal angle sensor.

A typical photoelectric shaft encoder consists of a shafting, a grating, a light source, and a photoreceiving element. When the main grating rotates with the main shaft, it overlaps with the indicating grating to form a moire fringe, and after photoelectric conversion, the photoelectric displacement signal corresponding to the rotation angle is output, and after electronic processing, and connected with the computer and the display device, the angular position can be realized. Real-time control and measurement.

Photoelectric shaft encoders are divided into two types: incremental and absolute. The encoder of the incremental encoder only needs two code channels, one is a circular grating, the scribe line spacing is uniform, corresponding to each resolution interval, an incremental pulse can be output; the other zero-bit raster can output the circumference number and The circle count start point mark signal is characterized by simple structure and small number of code channels, so it can be miniaturized, and the data structure can be arbitrary, but the disadvantage is that there is accumulated error, and all information is lost when a power failure occurs. Absolute encoders generally use a binary code disc. The code disc is encoded by multi-code channels. The code channels are arranged according to a certain regularity. There is a unique binary number corresponding to each resolution interval, so different numbers can be output at different positions. The code is characterized by a fixed zero position, a single value of the angular position, no cumulative error, and strong anti-interference ability, but the disadvantage is that there are many sensitive components, the code wheel is complicated, and the manufacturing cost is large.

In recent years, with the improvement of the accuracy of the metering grating and the development of the subdivision technology, the photoelectric shaft angle encoder has become a universally recognized precision angle measuring device. European and American countries also research and produce photoelectric shaft encoders as a basic device for automatic control. According to the applicant's knowledge, there have been some studies on the angle coding of encoder encoders in foreign countries, and the schemes for performing various angle coding on one code channel, such as those disclosed in EP 088624, EP094828, US 4,906,992, US 4,631,519, US 3,531,798. Program. However, due to the many shortcomings of these programs, their practical value has been reduced. To sum up, there are the following points: 1. Any scheme that performs angle coding on a single code channel has no pseudo-random scheme, which is more concise, because a lot of peripheral circuits are added to cooperate, and the number of components increases exponentially with the number of bits. And thus lose the promotion value. 2. There are also pseudo-random schemes for angular coding of code channels. However, in order to avoid the difficulty of compiling high-order pseudo-random codes, low-order pseudo-random codes are used in combination with other subdivision techniques to improve the angular resolution. This method generates electricity in addition to mixing In addition to road complexity, since the total number of symbols can only be 2 ⁿ , it also limits further promotion (that is, the number of divisions in the circle can only be a multiple of 2, otherwise it is not possible). 3. The literature also uses degraded ideas to adjust the data structure, but all use hard truncation, and the data inevitably produces heavy codes. In order to overcome the misjudgment caused by the re-code, a number of peripheral discriminating circuits have been added to identify this. This discriminating circuit can be quite complicated with the difference in position and degradation data. As the number of bits increases, the number of re-codes increases, and the reliability of the circuit decreases, eventually becoming an undesirable solution.

Summary of the invention

SUMMARY OF THE INVENTION The object of the present invention is to provide a novel optoelectronic rotation sensor capable of simultaneously obtaining position, direction and velocity signals by degrading pseudo-random coding of the code wheel circumference to absorb the advantages of the incremental and absolute photoelectric shaft encoders.

In order to achieve the above object, the technical solution adopted by the present invention is: A degenerate pseudo-random rotation sensor including a code disc, the innovation of which is: two code channels are provided on the code disc, wherein one is a periodic grating on a complete circumference The represented clock track, the other is a pseudo code track represented by a raster on a complete circumference; the pseudo code track is encoded on a complete circumference using a binary degenerate pseudo-random sequence, ie:

(1) On a complete circumference, a closed circle of m-bit binary code sequences is used to indicate that the complete circumference is divided into m equal parts, m being a positive integer;

(2) On the closed ring, take a continuous n-bit binary code as the angular position code, n >

4;

(3), the m and n meet the following inequalities:

m < 2 ⁿ ;

(4), on the closed ring composed of the m-bit binary code sequence, the angular position code formed by arbitrarily taking the consecutive n-bit binary code is unique, such that the total number of different angular position codes is m. The m different angular position codes exist in an angular relationship with the equal division of m equal parts on the complete circumference.

The relevant content in the above technical solutions is explained as follows:

1. In the above solution, the m and n satisfy the following inequalities better:

2 ^nl < m < 2

2, the concept of a complete binary pseudo-random sequence

Pseudo-random code (pseudo-random code) is also called pseudo-noise. It has the characteristics of random noise. Its main feature is that the autocorrelation coefficient has the largest origin and drops rapidly from the origin. Due to artificial production, there is a hidden law. Here we put in the binary! On top, a pseudo-random sequence with closed loop characteristics is called a complete pseudo-random code. The complete pseudo-random code sequence has a ]\!=2" element code, which is composed of a data string consisting of "1" or "0" connections. Here n is called The number of code bits. A complete pseudo-random sequence with an n-bit code, starting with any one of the digits on its closed circle, the code consisting of consecutive n-bit adjacent numbers is unique. Thus the complete pseudo-random code has M different codes.

3. The concept of degenerate binary pseudo-random sequences

If a pseudo-random sequence is a symbol of m < M-2 ⁿ , it is called an incomplete pseudo-random sequence. The process of changing from a complete pseudo-random sequence to an incomplete pseudo-random sequence is called degradation. If a number of sub-segments in the sequence are appropriately rounded off on the basis of a complete binary pseudo-random sequence, and the singularity of the code and the closure of the overall sequence are maintained during such rounding, the new sequence obtained by such processing It is called a degenerate pseudo-random code.

Because it is artificially active and purposefully controlled to degenerate, the code composed of the retained sequence satisfies the needs of actual work, so it has practical value in engineering technology. For example, if there are 512 codes in the 9-bit complete pseudo-random sequence, it can be degraded to 360 or 400 in the circumferential angle measurement, which makes it easier to establish contact with the degree, minute, second or dense system in the angle measurement. Can be degraded to 500, etc., in conjunction with other integer carry systems. Although in principle, a complete pseudo-random sequence can degenerate to any integer less than M, in general, the amount of degradation control is relatively large within 2 ¹¹ ^-1 , that is, the number of codes after degradation is

between. It should also be added here that for a specific completely pseudo-random sequence, it is not always able to degenerate to the required number. Therefore, finding a sequence suitable for the amount of degradation is another key to the compilation of degenerate pseudo-random codes.

4, with examples to illustrate the concept of complete binary pseudo-random code and degradation

In order to clarify the problem of complete binary pseudo-random code and degradation, a 4-bit data string is taken as an example. See Figure 1 for a Hamiltonian ring of 4-bit full binary pseudo-random codes with M = 16 data strings consisting of " or "0", as shown in Figure 1. The number of consecutive adjacent 4-bit codes is also 16 One can represent 16 states, as shown in Figure 2, and each code is unique. Now I want to reduce these 16 states to 13 states, that is, the amount of degradation is 3, using the complete binary pseudo-random in Figure 1. The sequence (data string) is not available. However, the data string in Fig. 1 is transformed to obtain a Hamiltonian ring composed of another 4-bit full binary pseudo-random code as shown in Fig. 3, and this group of 4 The 16 states of the complete binary pseudo-random (all shown in Figure 4) are degradable to 13 states, and the Hamiltonian ring of the 4-bit degenerate binary pseudo-random code shown in Figure 5 is from Figure 3. Degraded, its degradation amount is 3. The code indicated by the dotted line in Fig. 4 is removed, and the remaining solid line part is the 13 state display diagram of Fig. 5.

5, on the binary pseudo-random code degradation processing method

To completely solve the problem of pseudo-random sequence arrangement, it comes down to the pursuit of the Hamilton circle in Graph Theory. Because the Hamilton problem is a world-class problem that has not yet been overcome, There are still theoretical difficulties in seeking pseudo-random sequences. The contemporary computational science shows that the amount of computation that uses computer search and discriminating is explosively increasing with the increase of the number of bits n. It is known that the vast amount of astronomical digital is searched by computer, and the time is long. Can not accept. The following is a description of some data: the total number of permutations in the 5 digits is close to 4.3 billion, and the total number in the 6 digits is 1.8 trillion, while the total number in the 8th, 16th, and 32th positions is 1.2 x. 10 ⁷⁷ , 2.0 x l0 ¹⁹⁷²⁸ , 1.8 X 10 ^{5GS (M45} . As the number of bits n becomes larger, the number of complete pseudo-random sequences increases, but decreases compared with the total number of rows. A 4-bit complete The probability of seeking a sequence is one of 4096, and the probability of seeking for 5 digits drops to one of 1.67 million, and the probability of seeking more than 6 digits becomes smaller. It can be seen that high-order pseudo-random codes and high-order degradation are compiled. The work of pseudo-random codes is very difficult. However, we have explored the method of seeking degenerate pseudo-random codes. Through the in-depth study of such graphs on Hamiltonian, we can still use the method of combinatorial analysis. Practical meaning degenerate pseudo-random code.

We are currently making progress in the following three areas:

(1), a complete binary pseudo-random sequence can be sought.

(2) Degradation is performed while maintaining the singularity of the code and the closed loop of the overall sequence. Among them, when a complete binary pseudo-random sequence conforming to the Hamiltonian circle is found, if it cannot degenerate according to the required amount of degradation, its related complete binary pseudo-random sequence must not be degraded according to the amount of degradation. The so-called complete binary pseudo-random sequence refers to an inverse code sequence, an inverse code sequence, and an inverse code sequence.

(3) Deliberately controlling the amount of degradation and compiling the degenerate binary pseudo-random sequence expected. Regarding the specific compilation methods and techniques, there is a lot of knowledge about the mathematical foundation of the graph theory and the pseudo-random code, which will not be further discussed here.

6. The principle of the present invention is: Through the study of Graph Theory, it is found that there are M=2 ⁿ different codes in the n-bit pseudorandom bmary sequence. That is, a complete binary pseudo-random sequence, starting from any one of the digits on its closed circle, the code consisting of consecutive n-bit adjacent numbers is unique. Thus the complete binary pseudo-random sequence code must have M different codes (the code constitutes the Hamiltonian ring in the graph theory). If an analysis method such as transform combination is used, several sub-segments in the sequence can be rounded off for purposeful degradation processing, and finally a binary pseudo-random sequence suitable for degradation can be found and constitute a low-level Hamiltonian ( Hamilton) ring (that is, the degenerate pseudo-random sequence can still maintain the singularity of the code and the overall closed loop), this structure can be applied to the photoelectric axis encoder as a pseudo-code channel on the code wheel, and used The raster mode is represented to form a pseudo code track.

The present invention utilizes some research results of mathematical topological graph theory to degenerate the pseudo-random of the circumference Coding, thereby proposing a scheme for degenerating pseudo-random photoelectric rotating sensors. Due to the binary coding of this variable weight, the maximum savings and the use of space and time domain resources, this solution is applied to the photoelectric shaft angle encoder to simultaneously provide the output of the digital rotation parameters of position, velocity and direction, structurally As with incrementals, it's very compact and maintains data reliability like absolute.

The following is a comparison between the incremental, absolute and anti-counterfeit photoelectric shaft encoders.

It can be seen that the degenerate pseudo-random scheme almost retains the respective advantages of the former two types of encoders and abandons their respective shortcomings, which is an ideal solution.

DRAWINGS

Figure 1 is a closed circle of a 4-bit complete binary pseudo-random sequence.

Figure 2 is a representation of 16 different code representations of Figure 1 in successive 4 bits, the code representing the Hamiltonian ring in the graph.

Figure 3 is a closed ring of another 4-bit full binary pseudo-random sequence.

Figure 4 is a diagram showing the 16 different codes shown in Figure 3 by four consecutive digits. A Hamilton ring.

Figure 5 is a closed circle consisting of a degenerate binary pseudo-random sequence of Figure 3.

Figure 6 is a schematic view showing the structure of a optomechanical machine according to an embodiment of the present invention.

Figure 7 is a plan view of a code wheel in accordance with an embodiment of the present invention.

Figure 8 is a circuit schematic diagram of a first embodiment of the present invention.

In the above drawings: 1. Printed board with photodetector; 2. Code wheel; 3. Indicating grating; 4. Concentrating mirror; 5. Light source; 6. Bearing; 7. Spindle; 8. Clock code channel; Pseudo code channel; 10, photodetector; 11, shaping circuit; 12, arguing circuit; 13, shift register; 14, decoder; 15, output interface circuit.

detailed description

The present invention is further described below in conjunction with the accompanying drawings and embodiments:

Embodiment 1 A degenerate pseudo-random rotation sensor is composed of a optomechanical structure and a circuit. As shown in FIG. 6, the optomechanical structure of the present embodiment is composed of a printed board with a photodetector, a code wheel 2, an indicating grating 3, a condensing mirror 4, a light source 5, a bearing 6, and a main shaft 7. The connection relationship is as follows: The spindle 7 is located on the axis of rotation of the code wheel 2 and is fixedly coupled to the code wheel 2, which is rotatably supported by a bearing 6. The light source 5, the condensing mirror 4, and the indicating grating 3 form a projection optical path on the front side of the code wheel 2 with respect to the code track. The printed board with photodetector 1 is located on the reverse side of the code wheel 2, and its photodetector faces the projection light path. When the shaft 7 drives the code wheel 2 to rotate, under the action of the light source 5 and the condensing mirror 4, a rotationally variable optical signal is generated between the code wheel 2 and the indicating grating 3, and is converted into an electrical signal by the photodetector 10.

As shown in Fig. 7, the code wheel 2 is provided with two code tracks, one of which is a clock track 8 which is represented by a period grating on a full circumference, and the other is a pseudo code track 9 which is represented by a raster on a full circumference. The clock code 8 is located on the outer ring and functions to generate direction signals and speed signals. The pseudo code track 9 is a code track with a pseudo code raster pattern, and its function is to generate a position signal, which is defined here: "1" indicates light transmission, and "0" indicates opacity. The pseudo code channel 9 is encoded on a complete circumference using a six-bit binary degenerate pseudo-random sequence, specifically from a six-bit full binary pseudo-random code (sixty-four states) to a degenerate pseudo-random code having sixty states. which is:

(1), on a complete circumference, a closed circle of m-bit binary code sequences is used to indicate that the complete circumference is divided into m equal parts, m=60;

(2) on the closed ring, taking a continuous n-bit binary code as an angular position code, n=6;

(3), the m and n meet the following inequalities:

60 < 2 ⁶ =64;

(4), on the closed ring composed of the m=60 bit binary code sequence, the angular position code formed by arbitrarily taking consecutive n-6 bit binary codes is unique, such a set of different angular position codes The total number is m=60, and the m=60 different angular position codes have a one-to-one correspondence with the angular positions of m=60 equal parts on the complete circumference.

Six-bit complete binary pseudo-random code sequence M=2 ⁶ =64

0111 0101 1100 0110 1101 0011 1111 0111 1001 1001 0110 0001 0101 0001 0010 0000

The amount of degradation is 4, m=60

The underlined 4-bit code in the above six-bit complete binary pseudo-random code sequence is discarded, and the six-bit degenerate binary pseudo-random code sequence with a depreciation amount of 4 is obtained as follows:

0111 0101 1100 0110 1101 0011 1110 1111 0011 0010 1100 0010 1010 0010 0000

Press "1" for light transmission and "0" for opacity to obtain pseudo code track 9 in Figure 7.

As shown in FIG. 8, the circuit on the printed board 1 with the photodetector of the present embodiment is composed of a photodetector 10, a shaping circuit 11, a discriminating circuit 12, a shift register 13, a decoder 14, and an output interface circuit 15. composition. The photoelectric input signal is input in three ways, as shown in a, b, and c in FIG. 8, a and b are converted into clocks by the moire fringes formed between the clock track 8 (circular grating) of the code wheel 2 and the indicating grating 3. The signal, a, b, has a phase difference of 90°. c is a pseudo code signal directly converted from the pseudo code track 9 of the code wheel 2. a, b through the shaping circuit 11 into the defense circuit 12 output signal b ', "1" means the axis clockwise operation, "0" means the axis counterclockwise operation, thus obtaining the direction signal. Also as a shift direction signal of the shift register 13. a shaping circuit 11 outputs a signal a 'which is used as a speed signal to obtain a speed signal, and at the same time serves as a clock signal for the shift register 13. The c after the shaping circuit 11 is input to the shift register 13 as a pseudo code signal, and the parallel output pseudo code signal is decoded by the decoder 14 to output the position signal c '. The power amplification and level matching of a ', b ', c' through the output interface circuit 15 becomes the rotational digital parameter of the anti-aliasing photoelectric rotation sensor.

Embodiment 2: A degenerate pseudo-random rotation sensor consists of a optomechanical structure and a circuit. The difference from the first embodiment is mainly that the coding of the pseudo code channel uses a seven-bit binary degenerate pseudo-random sequence. Specifically:

Seven-bit complete binary pseudo-random sequence M=2 ⁷ =128

Oiii im om 1100 mi 0101 1110 oou 1011 0111 0100 mo 0101 1100

0011 0110 0110 1010 1101 0001 1001 0011 0001 0110 0000 1010 1001 0100 0010 0100 0100 0000

The amount of degradation is 28, 111=100

The underlined 28-bit code in the above seven-bit complete binary pseudo-random code sequence is discarded, and the seven-bit degenerate binary pseudo-random code sequence with a degraded amount of 28 is obtained as follows: Oooo oooT oioo oooi oooT oioi oioo

OTOO OOTO 0100 TOIO 0100 0000 HOT 0000 TTOO 1000 ΐΐοο δϊοδ nor οϊοδ

Τϊοδ TOo OOXO ΪΪΟΪ OOTO ΪΤΟΟ ΐδϊο Τϊοο οιτο ΤΪΟΪ ΟΠΟ ΪΤΟΟ οδοϊ τϊοϊ

τ ΠΟΟ OT OT τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ τ

9sz= _s z=mu 3⁄4Ι r arrow

: f .

°( φ ®^ ) ^m^mH "o,, "^IF^ «T _H

000000 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 OTOT om ooii oni om oooo ιττι οτοο ππ οοτο ττττ οπο ΤΙΤΪ

^3⁄4 9 ^^〖 soil ^ ^W^3⁄4I^H' iF ¹ ^ Υ Ding Simp

0000 Ϊ m m m OO OO OO OO m m m m m OO m m m m m OO OO OO OO OO OO OO OO m OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO OO ITO ΪΟΙΟ ΙΤΪΟ ΟΠΟ TITO ΙΪΤΟ ΟΟΟΪ ΪΟΟΙ ΧΙΪΟ ΧΙΪΟ 0101 ΪΙΙΟ ΪΤΟΪ ΤΧΪΟ

9SZ= ₈ Z=M Η i ^ - f ? ? h/ ^ Λ Ύ^- ^ ^

OOOO OOIO ΪΟΟΤ OIOT OOOO OITO TOOO ΪΧΟΟ XOOI 1000 ion ΟΤΟΪ 0Π0 OTTO IIOO OOXT 10X0 Olll OOTO ΪΙΙΟ TIOT TTOO Om ΙΟΪΟ ΪΠΪ

8

1^98100/ .00ZN3/X3d TfiCl70/800Z ΟΛ\ The underlined 76-bit code in the above-mentioned eight-bit complete binary pseudo-random code sequence is discarded, and the eight-bit degenerate binary pseudo-random code sequence with a degraded amount of 76 is obtained as follows:

1111 0110 1111 0100 1111 0010 1111 0000 1110 1110 1100 1110 1010 1110 1000 1111 1111 0111 1110 0111 1101 0111 1100 0111 0011 0111 0010 0111 0000 0110 1101 0110 1100 0000 1001 0100 1001 0000 1000 1010 1000 1000 0010 1000 0000

Press "1" for light transmission and "0" for opacity to obtain the corresponding pseudo code track (not shown). Others are the same as in the first embodiment, and the description thereof will not be repeated here.

Embodiment 5: A degenerate pseudo-random rotation sensor is composed of a optomechanical structure and a circuit. The difference from the first embodiment is mainly that the coding of the pseudo code channel uses an eight-bit binary degenerate pseudo-random sequence. Specifically:

Eight-bit complete binary pseudo-random sequence M=2 ⁸ =256

0111 1011 0111 1010 0111 1100 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0010 0101 0010 0100 0010

0010 1010 1000 1000 0010 1000 0000

The amount of degradation is 16, iii=240

The underlined 16-bit code in the above-mentioned eight-bit complete binary pseudo-random code sequence is discarded, and the eight-bit degenerate binary pseudo-random code sequence with a degraded amount of 16 is obtained as follows:

0111 1011 0111 1010 0111 1001 0111 1000 0111 0111 0110 0111 0101 0111 0100 0111 1111 0011 1110 1011 1110 0011 1001 1011 1001 0011 1000 1011 1000

0011 0110 1011 0110 0011 0101 0011 0100 1011 0100 0011 0011 0010 1011 0010 0011 0001 0011 0000 1011 0000 0010 0101 0010 0100 0010 0010 1010 1000 1000 0000

Press "for light transmission, "0" for opacity, and obtain a corresponding pseudo code track (not shown). Others are the same as in the first embodiment, and the description will not be repeated here.

The above embodiments are only for explaining the technical idea and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the essence of the present invention - a circular coding scheme with an unlimited number of codes and implementation thereof, and The physical protection structure (such as grating, induced electric field, magnetic recording, current, etc.) cannot be used for the purpose of making the protection range of the present invention, and the angle measurement or surveying instrument composed of the circumferential coding scheme cannot be used as a reason, and the present invention is limited. The scope of protection of the invention. Equivalent changes or modifications made in accordance with the spirit of the invention are intended to be included within the scope of the invention.

Claims

Profit request

A degenerate pseudo-random rotation sensor comprising a code wheel, wherein: the code wheel is provided with two code channels, wherein one is a clock code channel represented by a periodic grating on a complete circumference, and the other is complete a pseudo code track represented by a raster on the circumference; the pseudo code track is encoded on a complete circumference using a binary degenerate pseudo-random sequence, namely:

(2) On the closed ring, take a continuous n-bit binary code as the angular position code, n>

4;

(3), m and n meet the following inequalities:

m<2 ⁿ ;

2. A degenerate pseudo-random rotation sensor according to claim 1 wherein: said m > 2 ⁿ '