CN105823442A - Method for angle measurement through coded disc signal subdivision and photoelectric collimator - Google Patents

Abstract

In order to meet the ever-increasing needs of customers, and aiming at the technical situation of the existing grating code disc, the present invention provides a photoelectric aiming method for angle measurement by subdividing the code disc signal. The invention performs subdivision processing on the grating code disc signal of the photoelectric collimator, and obtains the angle measurement angle value by simulating and fitting the subdivision angle. While eliminating the influence of the DC component, the resolution and accuracy of the instrument are improved.

Description

Method for measuring angle by subdivision of code disc signal and photoelectric collimator

technical field

The present invention relates to the technical field of fixed aiming surveying and mapping, and more specifically relates to a method for measuring angles by subdividing code disc signals and a photoelectric collimator.

Background technique

The photoelectric collimator is an optical, mechanical and electrical device that integrates the functions of leveling, centering, telescope alignment, photoelectric collimation signal output, azimuth measurement, angle display and communication. It is widely used in aerospace, aviation and other fields. use. For example, as the application of photoelectric collimator in the fire control system, in the modern aircraft avionics system, only when the fire control radar and the photoelectric radar work together can the equipment's capabilities be fully utilized and the overall performance of the avionics system be optimal. Usually, a fire control system with fire control radar and photoelectric radar has two working states of main channel and auxiliary channel. The main and auxiliary channels are automatically determined by the system or manually selected by the pilot according to the control logic of the main and auxiliary channels. In the search state, the fire control radar and the photoelectric radar search for targets according to their respective working methods. When manually acquiring targets, only targets of interest are acquired through the main channel. After tracking the target, the main channel provides target indication for the auxiliary channel, and the auxiliary channel follows the main channel to intercept the same target. The photoelectric collimator realizes angle measurement by collecting the analog signal (sine wave signal) converted from the grating Moiré fringe light signal, and then processing it through hardware and software.

In the case of no subdivision, the resolution of the photoelectric collimator is directly proportional to the grid number of the grating code wheel. Due to the restriction of the grating marking process level and the production cost, the grid number of the commonly used code wheel is generally within two Less than 10,000 items. Therefore, in order to improve the resolution and accuracy of measurement and reduce the cost of instruments and equipment, the precision angle measurement system generally needs to adopt a subdivision method.

Contents of the invention

In order to meet the ever-increasing needs of customers, and aiming at the technical situation of the existing grating code disc, the present invention provides a photoelectric aiming method for angle measurement by subdividing the code disc signal, including:

(1) Acquisition of the Moiré fringe analog signal of the grating code disc;

(2) Preprocess the moiré fringe analog signal collected from the grating disc, and establish the relationship between the grating disc score line and the angle;

(3) Correcting the pre-processed moiré fringe analog signal of the grating code disc;

(4) Carry out waveform conversion to the preprocessed grating code disc Moiré fringe analog signal to obtain a large number of measured angles;

(5) Subdividing and correcting the preprocessed moiré fringe analog signal of the grating code disc to obtain the fraction of the measured angle;

(6) Calculate the measured angle θ according to the following formula:

θ＝80"×N+θ _a -θ _b ;

In the formula: N is the number of periods of the sine wave signal, and N is an integer, θ _a is a fraction less than a full period at the end point, and θ _b is a fraction less than a full period at the start point.

Further, the step (1) includes: using a 10-bit AD converter to collect the analog signal.

Further, the step (2) includes:

(21) Obtain two sinusoidal signals Asinθ and Acosθ from the collected grating code disc Moiré fringe analog signal;

(22) If 16,200 reticle lines are set on the entire circumference of the grating disc, the two sinusoidal signals will change by one cycle every time the reticle lines on the grating disc move by one pitch, which means that the angle has moved by 80″.

Further, the step (3) includes:

(31) The DC component UD is corrected and controlled in the following way when the grating code disc is installed structurally:

a) The jump value of the installation end face of the main shaft of the code disc shaft system;

b) Indicates the consistency of the height difference between the grating glass surface and the entire circumference of the installation ring surface

c) Jump value of main grating end after gluing;

d) The gap between the main grating and the indicating grating;

(32) Calculate the mean value of the DC component U _D :

Among them, U _D1 and U _D2 are the DC components of the moiré fringe analog signal of the grating code disc obtained by multi-point measurement;

(33) Amendment to U _S :

U _S = Asin Φ + U _D -D.

Further, the step (4) includes:

(41) Transforming the waveforms of the two sinusoidal signals to form a periodic pulse signal consistent with the two sinusoidal signals;

(42) Count the pulse signals to obtain the largest number of measured angles: 80″×N.

Further, the step (5) includes:

(51) A period 2π of the moiré fringe analog signal is equally divided into S parts, and S is the total number of subdivisions;

(52) convert Asinθ and Acosθ into digital quantities US and UC;

(53) Obtain tgθ or ctgθ according to the digital quantities US and UC:

$\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; g</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; |</span>\frac{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; S</span>}}}{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}}<span\; class="notranslate">\; |</span>$

$\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; g</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; |</span>\frac{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}}{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; S</span>}}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; ;</span>$

(54) judge which interval θ _b is in according to tgθ or ctgθ, and then obtain θ _b ;

(55) Calculate the fraction θ _a less than the full period at the end point, that is

θ _a =X×K

Wherein K=W/S, W is the grating pitch, 0≤Φ≤2π.

Further, the value of S is an integer of 4≤S≤8.

Further, for each subdivision interval, the maximum value of the DC component error can be known as:

Maximum subdivision error

The invention provides a photoelectric collimator for measuring angles by subdividing code disc signals, including:

The moiré fringe analog signal acquisition unit of the grating code disc is used to collect the moiré fringe analog signal of the grating code disc;

A preprocessing unit is used to preprocess the moiré fringe analog signal collected from the grating disk, and establish the relationship between the grating disk score line and the angle;

A correction unit is used to correct the preprocessed moire fringe analog signal of the grating code disc;

The large number calculation unit is used to perform waveform transformation on the preprocessed grating code disc Moiré fringe analog signal to obtain the large number of the measured angle;

The decimal calculation unit is used to subdivide and correct the preprocessed moiré fringe analog signal of the grating code disc to obtain the decimal of the measured angle;

The measured angle calculation unit is used to calculate the measured angle θ according to the following formula:

θ＝80"×N+θ _a -θ _b ;

In the formula: N is the number of periods of the sine wave signal, and N is an integer, θ _a is a fraction less than a full period at the end point, and θ _b is a fraction less than a full period at the start point.

Further, the moiré fringe analog signal acquisition unit of the grating code disc is a 10-bit AD converter.

The beneficial effects of the present invention are:

(1) While analyzing the impact of subdivided DC components, the accuracy and performance of the instrument are improved through digital optimization processing to meet the growing market demand;

(2) By subdividing the signal, high resolution can be obtained, which can reach 0.1″;

(3) High accuracy and precision of angle measurement;

(4) The processing of the subdivision error reduces the difficulty of the process and saves the cost of the instrument.

Description of drawings

Fig. 1 shows a flow chart of the photoelectric aiming method for angle measurement through code disc signal subdivision according to the present invention.

Fig. 2 shows the subdivision interval distribution map;

Figure 3 shows a schematic diagram of angle simulation;

Fig. 4 shows a schematic diagram of the influence of the DC component.

detailed description

The technical solution of the present invention will be described below in conjunction with the accompanying drawings.

As shown in Figure 1, the photoelectric aiming method for angle measurement through code disc signal subdivision includes:

(1) Acquisition of the Moiré fringe analog signal of the grating code disc;

(2) Preprocess the moiré fringe analog signal collected from the grating disc, and establish the relationship between the grating disc score line and the angle;

(3) Correcting the pre-processed moiré fringe analog signal of the grating code disc;

(4) Carry out waveform conversion to the preprocessed grating code disc Moiré fringe analog signal to obtain a large number of measured angles;

(5) Subdividing and correcting the preprocessed moiré fringe analog signal of the grating code disc to obtain the decimal point of the measured angle;

(6) Calculate the measured angle θ according to the following formula:

θ＝80"×N+θ _a -θ _b ;

In the formula: N is the number of periods of the sine wave signal, and N is an integer, θ _a is a fraction less than a full period at the end point, and θ _b is a fraction less than a full period at the start point.

Preferably, the step (1) includes: using a 10-bit AD converter to collect the analog signal.

Preferably, said step (2) includes:

(21) Obtain two sinusoidal signals Asinθ and Acosθ from the collected grating code disc Moiré fringe analog signal;

(22) If 16,200 reticle lines are set on the entire circumference of the grating disc, the two sinusoidal signals will change by one cycle every time the reticle lines on the grating disc move by one pitch, which means that the angle has moved by 80″.

Preferably, said step (3) includes:

(31) The DC component UD is corrected and controlled in the following way when the grating code disc is installed structurally:

a) The jump value of the installation end face of the main shaft of the code disc shaft system;

b) Indicates the consistency of the height difference between the grating glass surface and the entire circumference of the installation ring surface

c) Jump value of main grating end after gluing;

d) The gap between the main grating and the indicating grating;

(32) Calculate the mean value of the DC component U _D :

Among them, U _D1 and U _D2 are the DC components of the moiré fringe analog signal of the grating code disc obtained by multi-point measurement;

(33) Amendment to U _S :

U _S = Asin Φ + U _D -D.

Generally, 4 to 8 sampling points are taken (sampling every 45° or 90° within the entire circumference), and then the sampling calculation results are taken as instrument parameters into the angle calculation to eliminate the influence of the DC component.

Preferably, said step (4) includes:

(41) Transforming the waveforms of the two sinusoidal signals to form a periodic pulse signal consistent with the two sinusoidal signals;

(42) Count the pulse signals to obtain the largest number of measured angles: 80″×N.

Preferably, said step (5) includes:

(51) A period 2π of the moiré fringe analog signal is equally divided into S parts, and S is the total number of subdivisions;

(52) convert Asinθ and Acosθ into digital quantities US and UC;

(53) Obtain tgθ or ctgθ according to digital quantities US and UC, as shown in Figure 2:

$\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; g</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; |</span>\frac{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; S</span>}}}{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}}<span\; class="notranslate">\; |</span>$

$\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; g</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; |</span>\frac{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}}{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; S</span>}}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; ;</span>$

According to the polarity and absolute value of the digital quantities US and UC, Φ is divided into 8 subdivisions from 0° to 360°, as shown in Table 1.

Table 1 interval distribution table

interval Φ _US U _C | U _S |-|U _C | subdivision 0 0°～45° + + - X＝tgΦ 1 45°～90° + + + X＝1+ctgΦ 2 90°～135° + - + X＝2+tgΦ 3 135°～180° + - - X＝3+ctgΦ 4 180°～225° - - - X＝4+tgΦ 5 225°～270° - - + X＝5+ctgΦ 6 270°～315° - + + X＝6+tgΦ 7 315°～360° - + - X＝7+ctgΦ

In each interval, use MATLAB to fit and simulate the tgΦ value and establish a table, as shown in Figure 3, and calculate the Φ angle value according to the calculation results of the digital quantities US and UC.

The collimator uses a 10-bit AD converter to collect the analog signal, and creates a table for every 10″ subdivision interval. The subdivision value of the table is 512, and the angular resolution can reach 0.1″.

(54) judge which interval θ _b is in according to tgθ or ctgθ, and then obtain θ _b ;

(55) Calculate the fraction θ _a less than the full period at the end point, that is

θ _a =X×K

Where K=W/S, W is the grating pitch, 0≤Φ≤2π.

Preferably, the value of S is an integer of 4≤S≤8.

Preferably, as shown in FIG. 4 , the software subdivision requires that the dc component of the grating signal be eliminated before A/D conversion. Let the dc component be U _D , and the subdivision error caused by this component is error δ.

${\mathrm{<span\; class="notranslate">\; tg\&Phi;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; A</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; no</span>}\mathrm{<span\; class="notranslate">\; \&Phi;</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}}{\mathrm{<span\; class="notranslate">\; A</span>}\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; \&Phi;</span>}}$

but

$\mathrm{<span\; class="notranslate">\; \&Delta;</span>}\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; tg\&Phi;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; g</span>}\mathrm{<span\; class="notranslate">\; \&Phi;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}}{\mathrm{<span\; class="notranslate">\; A</span>}\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; \&Phi;</span>}}<span\; class="notranslate">\; .</span>$

For each subdivision interval, the maximum value of the DC component error can be known as:

Maximum subdivision error

The invention provides a photoelectric collimator for measuring angles by subdividing code disc signals, including:

The moiré fringe analog signal acquisition unit of the grating code disc is used to collect the moiré fringe analog signal of the grating code disc;

A preprocessing unit is used to preprocess the moiré fringe analog signal collected from the grating disk, and establish the relationship between the grating disk score line and the angle;

A correction unit is used to correct the preprocessed moire fringe analog signal of the grating code disc;

The large number calculation unit is used to perform waveform transformation on the preprocessed grating code disc Moiré fringe analog signal to obtain the large number of the measured angle;

The decimal calculation unit is used to subdivide and correct the preprocessed moiré fringe analog signal of the grating code disc to obtain the decimal of the measured angle;

The measured angle calculation unit is used to calculate the measured angle θ according to the following formula:

θ＝80"×N+θ _a -θ _b ;

In the formula: N is the number of periods of the sine wave signal, and N is an integer, θ _a is a fraction less than a full period at the end point, and θ _b is a fraction less than a full period at the start point.

Preferably, the moiré fringe analog signal acquisition unit of the grating code wheel is a 10-bit AD converter.

While the invention has been described with reference to specific embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, various adaptations of the teachings of the invention may be made to adapt a particular environment or material without departing from the scope of the invention. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but that it will include all implementations falling within the scope of the appended claims.

Claims (10)

1. A photoelectric aiming method for angle measurement through code disc signal subdivision, comprising: (1) Acquisition of the Moiré fringe analog signal of the grating code disc; (2) Preprocess the moiré fringe analog signal collected from the grating disc, and establish the relationship between the grating disc score line and the angle; (3) Correcting the pre-processed moiré fringe analog signal of the grating code disc; (4) Carry out waveform conversion to the preprocessed grating code disc Moiré fringe analog signal to obtain a large number of measured angles; (5) Subdividing and correcting the preprocessed moiré fringe analog signal of the grating code disc to obtain the decimal point of the measured angle; (6) Calculate the measured angle θ according to the following formula: θ＝80"×N+θ _a -θ _b ; In the formula: N is the number of periods of the sine wave signal, and N is an integer, θ _a is a fraction less than a full period at the end point, and θ _b is a fraction less than a full period at the start point. 2. The method according to claim 1, characterized in that the step (1) comprises: collecting the analog signal by using a 10-bit AD converter. 3. method according to claim 1, is characterized in that, described step (2) comprises: (21) Obtain two sinusoidal signals Asinθ and Acosθ from the collected grating code disc Moiré fringe analog signal; (22) If 16,200 reticle lines are set on the entire circumference of the grating disc, the two sinusoidal signals will change by one cycle every time the reticle lines on the grating disc move by one pitch, which means that the angle has moved by 80″. 4. method according to claim 1, is characterized in that, described step (3) comprises: (31) The DC component U _D is corrected and controlled in the following way when the grating code disc is structurally installed: a) The jump value of the installation end face of the main shaft of the code disc shaft system; b) Indicates the consistency of the height difference between the grating glass surface and the entire circumference of the installation ring surface c) Jump value of main grating end after gluing; d) The gap between the main grating and the indicating grating; (32) Calculate the mean value of the DC component U _D : Among them, U _D1 and U _D2 are the DC components of the moiré fringe analog signal of the grating code disc obtained by multi-point measurement; (33) Amendment to U _S : U _S = Asin Φ + U _D -D. 5. method according to claim 1, is characterized in that, described step (4) comprises: (41) Transforming the waveforms of the two sinusoidal signals to form a periodic pulse signal consistent with the two sinusoidal signals; (42) Count the pulse signals to obtain the largest number of measured angles: 80″×N. 6. method according to claim 1, is characterized in that, described step (5) comprises: (51) A period 2π of the moiré fringe analog signal is equally divided into S parts, and S is the total number of subdivisions; (52) convert Asinθ and Acosθ into digital quantities US and UC; (53) Obtain tgθ or ctgθ according to digital quantities US and UC: $\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; g</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; |</span>\frac{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; S</span>}}}{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}}<span\; class="notranslate">\; |</span>$ $\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; t</span>}\mathrm{<span\; class="notranslate">\; g</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; |</span>\frac{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; C</span>}}}{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; S</span>}}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; ;</span>$ (54) judge which interval θ _b is in according to tgθ or ctgθ, and then obtain θ _b ; (55) Calculate the fraction θ _a less than the full period at the end point, that is θ _a =X×K Where K=W/S, W is the grating pitch, 0≤Φ≤2π. 7. The method according to claim 6, wherein the value of S is an integer of 4≤S≤8. 8. The method according to claim 4, characterized in that, for each subdivision interval, the DC component error maximum value can be known: Maximum subdivision error 9. A photoelectric collimator for angle measurement through code disc signal subdivision, characterized in that it comprises: The moiré fringe analog signal acquisition unit of the grating code disc is used to collect the moiré fringe analog signal of the grating code disc; A preprocessing unit is used to preprocess the collected Moiré fringe analog signal of the grating disk, and establish the relationship between the grating disk score line and the angle; A correction unit is used to correct the preprocessed moiré fringe analog signal of the grating code disc; The large number calculation unit is used to perform waveform transformation on the preprocessed moiré fringe analog signal of the grating code disc to obtain the large number of the measured angle; The decimal calculation unit is used to subdivide and correct the preprocessed moiré fringe analog signal of the grating code disc to obtain the decimal of the measured angle; The measured angle calculation unit is used to calculate the measured angle θ according to the following formula: θ＝80"×N＋θ _a -θ _b ; In the formula: N is the number of periods of the sine wave signal, and N is an integer, θ _a is a fraction less than a full period at the end point, and θ _b is a fraction less than a full period at the start point. 10. The method according to claim 9, characterized in that, the moiré fringe analog signal acquisition unit of the grating code disc is a 10-bit AD converter.