CN1307226A

CN1307226A - Absolute encoding measuremnt method using circular grating

Info

Publication number: CN1307226A
Application number: CN 00112651
Authority: CN
Inventors: 叶盛祥; 魏爱敏; 王集交
Original assignee: Institute of Optics and Electronics of CAS
Current assignee: Institute of Optics and Electronics of CAS
Priority date: 2000-01-25
Filing date: 2000-01-25
Publication date: 2001-08-08
Anticipated expiration: 2020-01-25
Also published as: CN1157589C

Abstract

The measurement method uses the primary signal from circular grating as detecting element to obtain a series of output signals with successively doubled frequency via successive frequency dividing or successive detecting frequency dividing and frequency doubling. The output signals are used successively as codes for the bits of absolute periodic binary code to represent the measured angle. The said method has low cost and high reliability and is used in optoelectronic goniometric system.

Description

Circle grating specific coding measurement Law

The present invention is a kind of round grating specific coding measurement Law, belongs to the coding method that a kind of photo-electric angle that adopts round grating to make detecting element measures.

In the existing photo-electric angle metering, adopt circle grating increment counting measurement Law and coding measurement Law of absolute cycle of code-wheel usually.Circle grating increment counting method is to adopt the circle grating as angle detection device, and each primary signal of output is carried out stored count when the circle grating is rotated, and represents angle value with accumulative total.The advantage of this method is that method is simple, and the employed detecting element-low cost of manufacture of circle grating, technological process is short, size is little.But the defective of this method is that the result data reliability that obtains is relatively poor, and during because of stored count, being interfered is easy to generate many meters or counting loss, and counts or mistake that counting loss causes is saved in metering always and finishes more, so there is error in result data.And in detecting metering process, in case outage midway, then continuous data is lost immediately.

The absolute cycle compiling method of coding disk is to adopt coding disk to make angle detection device, utilizes that the multi-turn code channel carries out absolute cycle coding metering on the coding disk.This absolute cycle compiling method is to be carved with the multi-turn code channel on code-wheel, encloses the unitary code of the output signal of code channel as one group of binary periodic sign indicating number by each.In general, the number of turns of code channel is the figure place of binary periodic sign indicating number code on the code-wheel.The angle value that is measured is organized coded representation by this, and an angle value only has one group of unique code, and this group code of telegram in reply is constant after the outage.This coding method reliability height, but defective is that the manufacture process of angle detection device-code-wheel of being adopted is long, represent of binary periodic sign indicating number of angle value because of one on code-wheel circle code channel, therefore resolution and accuracy requirement are high more, the code channel number of code-wheel is many more, and the cost of making code-wheel is high more, and engineering process is long more, the photo-electric conversion element, amplifier and the corresponding electron device quantity that need are many more, so apparatus structure complexity is measured in its angle measurement, size is big.Sometimes, be subjected to the restriction of factors such as structure, possibly can't realize.

The objective of the invention is to overcome the deficiencies in the prior art, propose that a kind of method is simple, reliable, pick-up unit designs simplification, size be little, the round grating specific coding measurement Law of detecting element low cost of manufacture.

In order to achieve the above object, specific coding method of the present invention comprises the steps:

Select the original output signal of circle grating;

By this original signal being carried out signal level frequency division one by one, obtain the output signal that a series of frequencies reduce successively at double, until the output signal that obtains having only in 360 ° one-period;

Detection one by one is folded to subtract frequency division by this original signal is carried out, and can obtain the output signal that a series of frequencies reduce successively at double equally, until the output signal that obtains having only in 360 ° one-period;

By this original signal being carried out the stack of detection one by one frequency multiplication, obtain the output signal that a series of frequencies are multiplied successively;

With the lowest order code of the highest frequency output signal after this primary signal frequency multiplication as one group of absolute cycle code of binary system;

With the inferior low level code of the inferior high-frequency output signal after this primary signal frequency multiplication as the absolute cycle code of this group binary system;

The like, with a series of frequencies of obtaining behind this primary signal frequency multiplication and the frequency division successively at double the output signal of increase and decrease successively as every code of the absolute cycle code of this group binary system;

In behind the frequency division 360 °, only has the output signal of one-period as the inferior high-order code of the absolute cycle code of this group binary system;

Another output signal that will be orthogonal to the output signal of only having one-period in behind the primary signal frequency division 360 ° (generally cry sealing yard) is as the highest order of the absolute cycle code of this group binary system;

The angle value that represents detected metering with the absolute cycle codes of this group binary system.

The present invention is than prior art, following advantage is arranged: will justify the original stored count metering method of grating and change into the specific coding measurement Law, such angle value has only one group of unique code, overcome the easy many meters that produce of the original stored count metering of round grating method, leaked the error that meter causes, improved reliability.And the specific coding method of this invention does not need to use complicated code-wheel, and only need the short round grating of process for making to make detecting element, corresponding a large amount of electrooptical devices, amplifier and the electronic devices and components of having removed, therefore the manufacturing cost of angle measuring system is reduced greatly, structure is more simplified, and size is dwindled.Because specific coding method of the present invention is simple, reliable, so can be widely used in the various photo-electric angle measuring systems that round grating is made detecting element, it is very high or for once measure the important events of just finishing the test and measuring task to be particularly useful for reliability requirement.

Below in conjunction with drawings and Examples specific coding method of the present invention is further described.

Fig. 1 after for two quadratures (90 ° of phase differential) output Shaping of circle grating original output signal square-wave signal and this original signal carried out signal level a series of signal behind the frequency division one by one.

Fig. 2 is two the output square-wave signals of 90 ° of the phase differential of the original output signal in a certain position of circle grating and the level diagram of fractional frequency signal one by one thereof.

Fig. 3 is the original output signal of the circle grating folded schematic diagram that subtracts frequency division of detection one by one.

Fig. 4 has carried out the level diagram that each time output signal after subtracting is folded in three detections for the original output signal of circle grating.

Fig. 5 is the original output signal of the circle grating schematic diagram of detection stack frequency multiplication one by one.

Fig. 6 carries out the level diagram of each time output signal after three detections superpose for the original output signal of circle grating.

L among Fig. 1 ₀And L9 ₀It is the square wave (totally 8 cycles) after the original output signal shaping of round grating of two quadratures.With trigger to signal L ₉₀The forward position trigger and to obtain fractional frequency signal M one time ₀, to signal L ₉₀The back obtains another fractional frequency signal M along triggering ₉₀, signal M ₉₀With signal M ₀90 ° of phase differential.With another trigger to a signal M ₉₀Front and back along triggering respectively, obtain two secondary fractional frequency signal N respectively ₀And N ₉₀, signal N ₀And N ₉₀90 ° of phase differential.Frequency division can obtain signal P once more ₀And P ₉₀, as shown in Figure 1.And the like, in frequency division to 360 °, have only the signal of one-period.If the number of lines of circle grating is 8 (such as 8 cycles among Fig. 1), namely 23, then frequency division is three times, if the lines of circle grating are 2 ⁿ, then frequency division is n time, can obtain only having in 360 ° the signal of one-period.Get each time signal L ₀, M ₀, N ₀Z ₀And Z ₉₀As every code of one group of binary periodic sign indicating number, the tested angle value of this group coded representation.

Fig. 2 is the original signal L of circle grating ₀(as shown in Figure 1) and each time fractional frequency signal M ₀, N ₀, P ₀(as shown in Figure 1) level diagram.With each time signal L ₀, M ₀, N ₀, P ₀, P ₉₀As binary periodic sign indicating number every code of position from low to high, then can obtain the sign indicating number P of absolute cycle of scale-of-two of the tested angle value that the specific coding method represents ₉₀, P ₀, N ₀, M ₀, L ₀This level diagram and 5 coding disk code channel figure launch in full accord.For different angle values, the code of this group binary periodic code is different; For an angle value, the code value of this group binary periodic code is unique.As shown in Figure 2, for angle when the I district, the code of its binary periodic sign indicating number is 00001; For when the II district, the code of angle value is 00011; And the like.

D shown in Figure 3 ₀C ₁D ₁C ₂D ₂C ₃D ₃C ₄D ₄C ₅D ₅C ₆D ₆C ₇D ₇C ₈D ₈(below be abbreviated as D ₀C ₁C ₈D ₈) be the circle original output signal of grating (triangular wave, totally 8 cycles), get the high level C of this signal ₁C ₂C ₃C ₄C ₅C ₆C ₇C ₈Be a seisline, with C ₁D ₁C ₂, C ₃D ₃C ₄, C ₅D ₅C ₆, C ₇D ₇C ₈Fold and reduce to the high level position, form one time fractional frequency signal D ₀B ₁D ₂B ₂D ₄B ₃D ₆B ₄D ₈, the frequency ratio primary signal D of this signal ₀C ₁C ₈D ₈Low two times (i.e. 4 cycles).Get again the high level B of a signal ₁B ₂B ₃B ₄For the secondary seisline, with B ₁D ₂B ₂, B ₃D ₆B ₄The folded high level position of reducing to of part forms secondary fractional frequency signal D ₀A ₁D ₄A ₂D ₈, the frequency ratio of this signal is once believed D ₀B ₁D ₂B ₂D ₄B ₃D ₆B ₄Low two times, this primary signal D ₀C ₁C ₈D ₈Frequency low four times (i.e. 2 cycles).And the like, can obtain the fractional frequency signal output that a series of frequencies reduce successively at double, until the output signal that obtains having only in 360 ° one-period.

Fig. 4 is to the original output signal D of circle grating ₀C ₁C ₈D ₈(as shown in Figure 3) carried out the folded level diagram that subtracts rear each time frequency division output signal of three detections.Wherein, justify the original output signal D of grating ₀C ₁C ₈D ₈High level figure be H ₁H ₂, H ₃H ₄, H ₅H ₆, H ₇H ₈, H ₉H ₁₀, H ₁₁H ₁₂, H ₁₃H ₁₄, H ₁₅H ₁₆The high level figure that primary signal is carried out an output signal behind the frequency division is C ₁C ₂, C ₃C ₄, C ₅C ₆, C ₇C ₈The high level figure that primary signal is carried out the output signal behind the secondary frequency division is B ₁B ₂, B ₃B ₄The high level figure that primary signal is carried out three output signals behind the frequency division is A ₁A ₂In general, can obtain on the grating organizing the high level figure H of original output signal from circle with another of 90 ° of original signal phase differential ₁＇ H ₂＇, H ₃＇ H ₄＇, H ₅＇ H ₆＇, H ₇＇ H ₈＇, H ₉＇ H ₁₀', H ₁₁＇ H ₁₂＇, H ₁₃＇ H ₁₄＇, H ₁₅＇ H ₁₆＇ carries out the folded high level figure (pilot process is omitted) that can get the output signal behind a series of frequency divisions that subtracts of detection one by one equally to this signal, obtains having only in 360 ° the high level figure A of one-period equally at last ₁＇ A ₂＇, level A ₁＇ A ₂＇ and level A ₁A ₂90 ° of phase differential are with A ₁＇ A ₂＇ is as the sealing sign indicating number.The code-disc stretch-out view of level diagram shown in Figure 4 and 8 code-wheels is in full accord.If the line number of circle grating is 2 ⁿ, then carry out the folded signal that only has one-period in can frequency division to 360 ° that subtracts of n detection.Get output signal behind round grating primary signal and the frequency division as the code of one group of binary periodic code, the coded representation tested angle value of the absolute cycle code of this group binary system.

Shown in Figure 5, S ₀SS ₁₀Be the one-period signal in the circle original output signal of grating (triangular wave), get the intermediate value S of this signal amplitude ₁S ₂Be a seisline, with high level S ₁SS ₂Partial stack obtains first overtone signal S to the low level position ₀S ₁S ₆S ₂S ₁₀, the frequency ratio original signal S of this signal ₀SS ₁₀Senior Two is (i.e. two cycles) doubly.Get again signal S one time ₀S ₁S ₆S ₂S ₁₀The median E of amplitude ₁E ₂E ₃E ₄Be the secondary seisline, with high level E ₁S ₁E ₂And E ₃S ₂E ₄Partial stack has obtained secondary frequency multiplication signal S to the low level position ₀E ₁S ₄E ₂S ₆E ₃S ₈E ₄S ₁₀, the frequency ratio primary signal S of this signal ₀SS ₁₀High four times (i.e. 4 cycles) are than a signal S ₀S ₁S ₆S ₂S ₁₀The frequency Senior Two doubly.The like, primary signal is carried out one by one detection stack frequency multiplication, obtain the signal that a series of frequencies are multiplied successively, such as S among Fig. 5 ₀F ₁S ₃F ₂S ₄F ₃S ₅F ₄S ₆F ₅S ₇F ₆S ₈F ₇S ₉F ₈S ₁₀And S ₀G ₁H ₁G ₂S ₃G ₃H ₂G ₄S ₄G ₅H ₃G ₆S ₅G ₇H ₄G ₈S ₆G ₉H ₅G ₁₀S ₇G ₁₁H ₆G ₁₂S ₈G ₁₃H ₇G ₁₄S ₉G ₁₅H ₈G ₁₆S ₁₀In like manner, other cycle of the original output signal of circle grating can be carried out the stack of detection one by one frequency multiplication equally, obtains the frequency-doubled signal of the original output signal of whole round grating.

Fig. 6 is the original output signal S to the circle grating ₀SS ₁₀Carried out the level diagram of each time signal of obtaining after three detections stacks frequency multiplication.Wherein, the level diagram to the output signal after the original output signal first overtone is E ₁E ₂, E ₃E ₄Be F to the output signal level figure behind the original output signal secondary frequency multiplication ₁F ₂, F ₃F ₄, F ₅F ₆, F ₇F ₈Be G to the output signal level figure after three frequencys multiplication of original output signal ₁G ₂, G ₃G ₄, G ₅G ₆, G ₇G ₈, G ₉G ₁₀, G ₁₁G ₁₂, G ₁₃G ₁₄, G ₁₅G ₁₆These three output signal frequency are multiplied successively.In these level diagrams each is successively as lowest order in the binary periodic sign indicating number, inferior low level ... code.

Claims

1. a round grating specific coding measurement Law is characterized in that comprising the steps:

Select the original output signal of circle grating;

Detection one by one is folded to subtract frequency division by this original signal is carried out, and also can obtain the output signal that a series of frequencies reduce successively at double, until the output signal that obtains having only in 360 ° one-period;

In 360 °, only has the output signal of one-period as the inferior high-order code of the absolute cycle code of this group binary system;

Will with 360 ° in only have the phase of output signal of one-period to differ from another output signal of 90 °, namely the signal (obtaining by frequency division) of sealing code is as the highest order code of the absolute cycle code of this group binary system;

Angle value with the detected metering of the absolute cycle representation of this group binary system.