CN107449375A - A kind of increment type Circular gratings chi grating Angular Displacement Detecting System and method - Google Patents
A kind of increment type Circular gratings chi grating Angular Displacement Detecting System and method Download PDFInfo
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- CN107449375A CN107449375A CN201710773144.4A CN201710773144A CN107449375A CN 107449375 A CN107449375 A CN 107449375A CN 201710773144 A CN201710773144 A CN 201710773144A CN 107449375 A CN107449375 A CN 107449375A
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- 238000006073 displacement reaction Methods 0.000 title claims abstract description 56
- 238000000034 method Methods 0.000 title claims abstract description 16
- 238000001514 detection method Methods 0.000 claims abstract description 24
- 238000007493 shaping process Methods 0.000 claims abstract description 11
- 238000006243 chemical reaction Methods 0.000 claims abstract description 7
- 238000003708 edge detection Methods 0.000 claims description 7
- 238000004364 calculation method Methods 0.000 claims description 6
- 230000001678 irradiating effect Effects 0.000 claims description 3
- 230000000630 rising effect Effects 0.000 claims description 3
- 238000005259 measurement Methods 0.000 abstract description 10
- 238000005286 illumination Methods 0.000 abstract description 9
- 238000003491 array Methods 0.000 abstract 4
- 238000010586 diagram Methods 0.000 description 8
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/26—Measuring arrangements characterised by the use of optical techniques for measuring angles or tapers; for testing the alignment of axes
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Abstract
The present invention relates to a kind of increment type Circular gratings chi grating Angular Displacement Detecting System and method, system includes source of parallel light, increment type Circular gratings chi, photosensor arrays, signal processing unit, angular displacement display unit and high speed voltage comparator；Wherein, the direction of illumination of the vertical parallel light source of increment type Circular gratings chi；Photosensor arrays are positioned in the increment type Circular gratings chi grating pitch, and are uniformly distributed in step type；High speed voltage comparator is connected between photosensor arrays and signal processing unit, and shaping is carried out to photosensor arrays output signal and the square-wave signal drawn to shaping carries out level conversion；The signal processing unit is connected with angular displacement display unit, and the value of angular displacement being calculated is included on angular displacement display unit.The present invention has the advantages that composition is simple, testing cost is low, measurement accuracy is high, detection speed is fast, practical.
Description
Technical Field
The invention relates to the technical field of precision measurement, in particular to an incremental circular grating ruler grating angular displacement detection system and method.
Background
In precision measurement, a circular grating ruler is used as an important tool, and linear displacement and angular displacement are mainly measured by utilizing the optical principle of a grating.
The key technology and difficulty of the circular grating ruler are that the quality of the grating directly affects the precision and reliability of the detection result in the manufacturing of the grating. The existing circular grating ruler mainly comprises a glass circular grating ruler and a metal circular grating ruler, and the forms of the existing circular grating ruler comprise an incremental circular grating ruler and an absolute circular grating ruler.
The incremental circular grating ruler needs a reference signal (relative zero point), and a reference point return-to-zero operation needs to be executed during power-on. When the power is lost, the grating ruler must return to zero again, so that the equipment cannot recover the operation. In addition, when the speed is too fast, the pulse signal is lost to affect the accuracy. The absolute circular grating ruler is characterized in that a code channel with absolute position codes is engraved on a scale grating, each position corresponds to a fixed code channel, a measurement indication value is only related to the initial position and the final position of measurement and is not related to the middle measurement process, the current position can be recovered after power failure, and the anti-interference performance is good. However, the absolute grating ruler has complex coding, high manufacturing cost and slow reading speed, and needs to be scribed on the scale grating, and the measurement precision of the absolute grating ruler has a great relationship with the precision of the scale grating, so that the absolute grating ruler has high requirements on the scribing of the scale grating in high-precision measurement, thereby increasing the processing cost.
How to measure the angular displacement of the grating with high precision and high speed under the condition of low detection cost becomes a problem to be solved urgently.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides the incremental circular grating ruler grating angular displacement detection system which is simple in structure, low in detection cost, high in measurement precision, high in detection speed and strong in practicability.
In order to achieve the purpose, the technical scheme provided by the invention is as follows:
an incremental circular grating ruler grating angular displacement detection system comprises a parallel light source, an incremental circular grating ruler, a photoelectric sensor array, a signal processing unit, an angular displacement display unit and a high-speed voltage comparator; the incremental circular grating ruler is vertical to the irradiation direction of the parallel light source; the photoelectric sensor array is arranged in the grating pitch of the incremental circular grating ruler and is uniformly distributed in a step shape; the high-speed voltage comparator is connected between the photoelectric sensor array and the signal processing unit, and is used for shaping the output signal of the photoelectric sensor array and carrying out level conversion on a square wave signal obtained by shaping; the signal processing unit is connected with the angular displacement display unit and displays the calculated angular displacement value on the angular displacement display unit.
Further, the number n of photosensors is (H-D)/(D + L) + 1; the offset angle x is (w-q)/(n-1); wherein q is an angle corresponding to the nth photoelectric sensor, and w is an angle between the two grid lines; h is the length of the grid line; d is the width of the photoelectric sensor in the length direction of the grid line; x is the dislocation angle of two adjacent photoelectric sensors in the rotation direction of the circular grating ruler; l is an adjacent gap.
In order to achieve the above object, the present invention further provides an incremental circular grating scale grating angular displacement detection method for the above system: the method comprises the following steps:
s1, irradiating the light emitted from the parallel light source onto the incremental circular grating ruler;
s2, the photoelectric sensor array receives light, and outputs a high level signal and a low level signal according to whether the grating grid lines shield the light;
s3, shaping and level conversion are carried out on the output level signal by the high-speed voltage comparator;
s4, the signal processing unit receives the shaped and level-converted signal, and carries out signal edge detection, grating motion direction judgment and counting on the signal to obtain an angular displacement value;
and S5, the angular displacement display unit displays the angular displacement value processed by the signal processing unit.
Further, in step S4, the movement direction is determined by the combinational logic according to the characteristics of the signals A, B, C output by the three adjacent photosensors respectively; in the case of clockwise movement, the direction of movement isIn the case of counterclockwise motion, the direction of motion is
Further, the signal processing unit performs pulse edge detection and counting by using an edge detection method, and the required detection edge is a rising edge of the pulse.
Further, the grating angular displacement value calculation process is as follows:
when the grating moves clockwise, the angular displacementThe calculation formula is as follows:wherein,the angular displacement value of the previous time is shown, omega is the angular displacement corresponding to one grid pitch, N is the number of sensors arranged in one grid pitch, and M is the number of counted pulses; when the grating is moved in a counter-clockwise direction,
compared with the prior art, the principle of the scheme is as follows:
the parallel light source irradiates the incremental circular grating ruler, because the photoelectric sensor has high sensitivity to the illumination intensity, the photoelectric sensor which is not shielded by the grating ruler grid line receives all illumination and outputs a high level signal, the shielded photoelectric sensor receives partial illumination or does not receive illumination, the illumination intensity is low, and a low level signal is output. When the photoelectric sensor detects the change of the illumination intensity, the output waveform is not an ideal square wave signal, and the output signal needs to be shaped. The scheme adopts the high-speed voltage comparator to reshape the output signal of the photoelectric sensor, output a square wave signal, convert the signal into high and low levels and output the signals to the signal processing unit, detect the edge of a pulse signal, judge the movement direction of a grating and count the movement direction of the grating, and finally obtain the angular displacement value of the grating.
Compared with the prior art, the method has the following advantages:
1. signals of the displacement detection method are directly output by the photoelectric sensor, and the detection speed is high;
2. the system is simplified, and the detection cost is low;
3. the practicability is strong: the requirement on the photoelectric sensor is low, and the displacement value can be obtained only by detecting and counting the shaped pulse edges.
Drawings
FIG. 1 is a schematic structural diagram of an incremental circular grating scale grating angular displacement detection system according to the present invention;
FIG. 2 is an enlarged view of a portion 101 of FIG. 1;
FIG. 3 is a diagram illustrating a distribution of photo-sensors within a grating pitch according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of an initial position of the grating scale moving clockwise according to the embodiment of the present invention;
fig. 5, 6, 7, 8, 9, 10 and 11 are schematic diagrams illustrating seven positions and corresponding output signals experienced by the incremental circular grating scale during clockwise movement according to the embodiment of the present invention;
FIG. 12 is a schematic diagram illustrating characteristics of an output signal according to a clockwise motion determination in an embodiment of the invention;
fig. 13, 14, 15, 16, 17, 18, and 19 are schematic diagrams of seven positions and corresponding output signals experienced by the incremental circular grating ruler after sudden reversing movement in the clockwise movement process in the embodiment of the present invention;
FIG. 20 is a schematic diagram illustrating characteristics of an output signal according to which a direction of a grating scale is suddenly reversed when the grating scale moves clockwise according to an embodiment of the present invention;
FIG. 21 is a block diagram of a combinational logic circuit for determining direction according to an embodiment of the present invention.
Detailed Description
The invention will be further illustrated with reference to specific examples:
referring to fig. 1-3, the incremental circular grating scale angular displacement detection system according to this embodiment includes a parallel light source 1, an incremental circular grating scale 2, a photosensor array 3, a signal processing unit 4, an angular displacement display unit 5, and a high-speed voltage comparator 6; the incremental circular grating ruler 2 is vertical to the irradiation direction of the parallel light source 1; the photoelectric sensor array 3 is arranged in the grating pitch of the incremental circular grating ruler 2 and is uniformly distributed in a step shape; the number n of the photoelectric sensors is (the length of the grid line H-the width D of the photoelectric sensors in the length direction of the grid line)/(the width D of the photoelectric sensors in the length direction of the grid line + the adjacent gaps L between the photoelectric sensors); the offset angle x is (the angle w between the two grid lines-the angle q corresponding to the nth photosensor)/(the number of photosensors n-1); the high-speed voltage comparator 6 is connected between the photoelectric sensor array 3 and the signal processing unit 4, and is used for shaping the output signal of the photoelectric sensor array 3 and carrying out level conversion on the square wave signal obtained by shaping; the signal processing unit 4 is connected with an angular displacement display unit 5.
The system works as follows:
s1, irradiating the light emitted from the parallel light source 1 onto the incremental circular grating ruler 2;
s2, the photoelectric sensor array 3 receives illumination and outputs a high level signal and a low level signal according to whether the grating grid lines shield the illumination;
s3, shaping and level conversion are carried out on the output level signal by the high-speed voltage comparator 6;
s4, the signal processing unit 4 receives the shaped and level-converted signal, and carries out signal edge detection, grating motion direction judgment and counting on the signal to obtain an angular displacement value; the method comprises the following specific steps:
s41, assuming that the incremental circular grating scale 2 moves clockwise relative to the photoelectric sensor, and at an initial time 0, the distribution of the photoelectric sensor in the grating pitch and the corresponding output signal are as shown in fig. 4;
s42, at the time 1 of movement, the photo sensor is shielded by the grating lines, the non-shielded photo sensor outputs a high level, and the shielded photo sensor outputs a low level, in this embodiment, for convenience of detection, the signal is inverted, that is, the shielded sensor outputs a high level, otherwise, the signal outputs a low level (hereinafter, the descriptions are based on this), as shown in fig. 5;
s43, continuing to move forward to the time points 2, 3, 4, 5, 6, 7, the corresponding signals are shown in fig. 6, fig. 7, fig. 8, fig. 9, fig. 10, fig. 11 respectively;
s44, judging the direction by using combinational logic according to the characteristics of the output signals of three adjacent photoelectric sensors, wherein the combinational logic circuit is as shown in the figure21 is shown in the figure; it is assumed that the output signals of the photosensors 1, 2, and 3 correspond to A, B, C; in the case of clockwise movement, the direction of movement isAs shown in fig. 12; on the contrary, if the grating ruler moves anticlockwise relative to the sensor, the signal output starts from the number n of the photoelectric sensor, and the moving direction is
S45, assuming that the direction changes suddenly during the movement, the direction is determined by using the combinational logic, and the movement is performed counterclockwise to the time points 8, 9, 10, 11, 12, 13, and 14, where the corresponding signals are shown in fig. 13, 14, 15, 16, 17, 18, and 19, respectively;
s46, the signal processing unit 4 detects and counts the pulse edge by using an edge detection method, and the edge to be detected is the rising edge of the pulse; the calculation process of the grating angular displacement value is as follows:
when the grating moves clockwise, the angular displacementThe calculation formula is as follows:wherein,the angular displacement value of the previous time is shown, omega is the angular displacement corresponding to one grid pitch, N is the number of sensors arranged in one grid pitch, and M is the number of counted pulses; when the grating is moved in a counter-clockwise direction,
and S5, the angular displacement display unit 5 displays the displacement value processed by the signal processing unit 4.
The embodiment has the advantages of simple structure, low detection cost, high measurement precision, high detection speed, strong practicability and the like.
The above-mentioned embodiments are merely preferred embodiments of the present invention, and the scope of the present invention is not limited thereto, so that variations based on the shape and principle of the present invention should be covered within the scope of the present invention.
Claims (6)
1. The utility model provides an incremental formula circular grating chi grating angular displacement detecting system which characterized in that: the device comprises a parallel light source (1), an incremental circular grating ruler (2), a photoelectric sensor array (3), a signal processing unit (4), an angular displacement display unit (5) and a high-speed voltage comparator (6); the incremental circular grating ruler (2) is vertical to the irradiation direction of the parallel light source (1); the photoelectric sensor array (3) is arranged in the grating pitch of the incremental circular grating ruler (2) and is uniformly distributed in a step shape; the high-speed voltage comparator (6) is connected between the photoelectric sensor array (3) and the signal processing unit (4) and is used for shaping the output signal of the photoelectric sensor array (3) and performing level conversion on the square wave signal obtained by shaping; the signal processing unit (4) is connected with the angular displacement display unit (5), and the calculated angular displacement value is displayed on the angular displacement display unit (5).
2. The incremental circular grating scale grating angular displacement detection system of claim 1, wherein: the number n of the photoelectric sensors is (H-D)/(D + L) + 1; the offset angle x is (w-q)/(n-1); wherein q is an angle corresponding to the nth photoelectric sensor, and w is an angle between the two grid lines; h is the length of the grid line; d is the width of the photoelectric sensor in the length direction of the grid line; x is the dislocation angle of two adjacent photoelectric sensors in the rotation direction of the circular grating ruler; l is an adjacent gap.
3. An incremental circular grating scale grating angular displacement detection method for the system of claim 1, wherein: the method comprises the following steps:
s1, irradiating the light emitted from the parallel light source onto the incremental circular grating ruler;
s2, the photoelectric sensor array receives light, and outputs a high level signal and a low level signal according to whether the grating grid lines shield the light;
s3, shaping and level conversion are carried out on the output level signal by the high-speed voltage comparator;
s4, the signal processing unit receives the shaped and level-converted signal, and carries out signal edge detection, grating motion direction judgment and counting on the signal to obtain an angular displacement value;
and S5, the angular displacement display unit displays the angular displacement value processed by the signal processing unit.
4. The incremental circular grating scale grating angular displacement detection method of claim 3, wherein: the signal processing unit detects and counts pulse edges by using an edge detection method, and the edge to be detected is a rising edge of the pulse.
5. The incremental circular grating scale grating angular displacement detection method of claim 3, wherein: in the step S4, the movement direction is determined by using combinational logic according to characteristics of signals A, B, C respectively output by three adjacent photosensors; in the case of clockwise movement, the direction of movement isIn the case of counterclockwise motion, the direction of motion is
6. The incremental circular grating scale grating angular displacement detection method of claim 3, wherein: the calculation process of the grating angular displacement value is as follows:
when the grating moves clockwise, the angular displacementThe calculation formula is as follows:wherein,the angular displacement value of the previous time is shown, omega is the angular displacement corresponding to one grid pitch, N is the number of sensors arranged in one grid pitch, and M is the number of counted pulses; when the grating is moved in a counter-clockwise direction,
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Cited By (2)
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| CN111060002A (en) * | 2018-10-17 | 2020-04-24 | 韩国标准科学研究院 | Absolute position measuring method and absolute position measuring device |
| CN112254665A (en) * | 2020-09-09 | 2021-01-22 | 杭州电子科技大学 | High-precision digital circular division sensor, system and detection method |
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| CN112254665A (en) * | 2020-09-09 | 2021-01-22 | 杭州电子科技大学 | High-precision digital circular division sensor, system and detection method |
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