CN107449375A - A kind of increment type Circular gratings chi grating Angular Displacement Detecting System and method - Google Patents

Abstract

The invention relates to a system and method for detecting angular displacement of an incremental circular grating ruler. The system includes 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 perpendicular to the irradiation direction of the light source; the photoelectric sensor array is placed in the grating pitch of the incremental circular grating ruler, and is uniformly distributed in a stepped manner; the high-speed voltage comparator is connected to the photoelectric sensor array and signal processing Between the units, the output signal of the photoelectric sensor array is reshaped and the square wave signal obtained by the reshaping is converted; the signal processing unit is connected with the angular displacement display unit, and the calculated angular displacement value is displayed on the angular displacement display on the unit. The invention has the advantages of simple structure, low detection cost, high measurement precision, fast detection speed, strong practicability and the like.

Description

A system and method for detecting angular displacement of an incremental circular grating ruler

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 technique

In precision measurement, the circular grating scale is an important tool, using the optical principle of the grating, mainly for the measurement of linear displacement and angular displacement.

The key technology and difficulty of the circular grating ruler is mainly in the manufacture of the grating, the quality of the grating will directly affect the accuracy and reliability of the detection results. The existing circular grating scales mainly include glass circular grating scales and metal circular grating scales, and their forms include incremental circular grating scales and absolute circular grating scales.

Among them, the incremental circular grating ruler needs a reference signal (relative to the zero point), and the reference point must be returned to zero when the power is turned on. When power is lost, the scale must be reset to zero so that the device cannot resume operation. In addition, when the speed is too fast, the pulse signal will be lost and the accuracy will be affected. The absolute circular grating scale is to engrave a code track with an absolute position code on the scale grating, and each position corresponds to a fixed code track. The measured value is only related to the starting and ending positions of the measurement, and the middle The measurement process is irrelevant, and the current position can be restored after power failure, with good anti-interference performance. However, the encoding of the absolute grating scale is complicated, the manufacturing cost is high, and the reading speed is slow. It needs to be engraved on the scale grating. The wire requirements are very high, which increases 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 has become an urgent problem to be solved.

Contents of the invention

The object of the present invention is to overcome the deficiencies of the prior art, and provide an incremental circular grating ruler grating angular displacement detection system with simple structure, low detection cost, high measurement accuracy, fast detection speed and strong practicability.

In order to achieve the above object, the technical scheme provided by the present invention is:

An incremental circular grating ruler grating angular displacement detection system, which includes 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; wherein, the incremental circular grating The grating ruler is vertical and parallel to the irradiation direction of the light source; the photoelectric sensor array is placed in the grating pitch of the incremental circular grating ruler, and is uniformly distributed in a stepped manner; the high-speed voltage comparator is connected between the photoelectric sensor array and the signal processing unit, Reshaping the output signal of the photoelectric sensor array and performing level conversion on the 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 of photoelectric sensors n=(H-D)/(D+L)+1; misalignment angle x=(w-q)/(n-1); wherein, q is the angle corresponding to the nth photoelectric sensor, w is the angle between two grating lines; H is the length of the grating line; D is the width of the photoelectric sensor in the direction of the length of the grating line; x is the misalignment angle of two adjacent photoelectric sensors in the rotation direction of the circular scale; L is the adjacent gap .

In order to achieve the above object, the present invention additionally provides a method for detecting angular displacement of the incremental circular grating ruler for the above system: comprising the following steps:

S1. The light emitted from the parallel light source shines on the incremental circular grating scale;

S2. The photoelectric sensor array receives light, and outputs a high-level signal and a low-level signal according to whether it is blocked by the grating line;

S3. The high-speed voltage comparator performs shaping and level conversion on the output level signal;

S4. The signal processing unit receives the shaped and level-converted signal, detects the signal edge, judges the moving direction of the grating and counts it, and obtains the angular displacement value;

S5. The angular displacement display unit displays the angular displacement value processed by the signal processing unit.

Further, in step S4, the direction of motion is judged by combination logic according to the characteristics of the signals A, B, and C respectively output by three adjacent photoelectric sensors; in the case of clockwise motion, the direction of motion is In the case of counterclockwise movement, the direction of movement is

Further, the signal processing unit uses an edge detection method to detect and count pulse edges, and the required detection edge is the rising edge of the pulse.

Further, the calculation process of the angular displacement value of the grating is as follows:

When the grating moves clockwise, the angular displacement The calculation formula is: in, is the previous angular displacement value, ω is the angular displacement corresponding to a grating pitch, N is the number of sensors placed within a grating pitch, M is the number of counted pulses; when the grating moves counterclockwise,

Compared with the existing technology, the principle of this scheme is as follows:

The parallel light source shines on the incremental circular grating scale. Since the photoelectric sensor is highly sensitive to light intensity, the photoelectric sensor not blocked by the grating line receives all the light and outputs a high-level signal, and the blocked photoelectric sensor receives part of the light. Or do not receive light, the light intensity is low, and output a low-level signal. Since the output waveform of the photoelectric sensor is not an ideal square wave signal when detecting changes in light intensity, it is necessary to reshape the output signal. This program uses a high-speed voltage comparator to shape the output signal of the photoelectric sensor, output a square wave signal, and convert the signal from high to low level and output it to the signal processing unit, detect the edge of the pulse signal and judge the moving direction of the grating and count, and finally get the grating Angular displacement value.

Compared with the prior art, it has the following advantages:

1. The signal of the displacement detection method is directly output by the photoelectric sensor, and the detection speed is fast;

2. The system is simplified and the detection cost is low;

3. Strong practicability: low requirements for photoelectric sensors, only need to detect and count the shaped pulse edges to get the displacement value.

Description of drawings

Fig. 1 is the structural representation of a kind of incremental circular grating ruler grating angular displacement detection system among the present invention;

Fig. 2 is a partial enlarged view of part 101 in Fig. 1;

Fig. 3 is the distribution diagram of the photoelectric sensor in the grating pitch in the embodiment of the present invention;

Fig. 4 is a schematic diagram of the initial position of the clockwise movement of the grating ruler in the embodiment of the present invention;

Fig. 5, Fig. 6, Fig. 7, Fig. 8, Fig. 9, Fig. 10 and Fig. 11 are the seven positions experienced by the clockwise movement of the incremental circular grating ruler in the embodiment of the present invention and the corresponding output signals schematic diagram;

12 is a schematic diagram of the characteristics of the output signal based on which the clockwise motion direction is judged in the embodiment of the present invention;

Fig. 13, Fig. 14, Fig. 15, Fig. 16, Fig. 17, Fig. 18, and Fig. 19 are the seven positions experienced by the incremental circular grating ruler in the clockwise movement process after the sudden reversing movement in the embodiment of the present invention and A schematic diagram of the corresponding output signal;

Fig. 20 is a schematic diagram of the characteristics of the output signal on which the judgment of the direction of motion is suddenly reversed when the grating scale is moving clockwise in the embodiment of the present invention;

Fig. 21 is a circuit diagram of combinational logic for judging direction in the embodiment of the present invention.

detailed description

The present invention will be further described below in conjunction with specific embodiment:

Referring to the accompanying drawings 1-3, the angular displacement detection system of an incremental circular grating ruler described in this embodiment includes a parallel light source 1, an incremental circular grating ruler 2, a photoelectric sensor array 3, and a signal processing unit 4. The angular displacement display unit 5 and the high-speed voltage comparator 6; wherein, the incremental circular grating ruler 2 is perpendicular to the irradiation direction of the light source 1; the photoelectric sensor array 3 is placed in the grating pitch of the incremental circular grating ruler 2, And it is uniformly distributed in a stepwise shape; the number of photoelectric sensors n=(grid line length H-the width D of the photoelectric sensor in the length direction of the grid line)/(the width D of the photoelectric sensor in the length direction of the grid line D+the adjacent gap L between the photoelectric sensors) Misalignment angle x=(angle w between two grating lines-angle q corresponding to the nth photoelectric sensor)/(photoelectric sensor number n-1); High-speed voltage comparator 6 is connected to photoelectric sensor array 3 and Between the signal processing unit 4 , the output signal of the photoelectric sensor array 3 is reshaped and the square wave signal obtained by the reshaping is transformed; the signal processing unit 4 is connected with the angular displacement display unit 5 .

The working process of the system is as follows:

S1. The light emitted from the parallel light source 1 is irradiated onto the incremental circular grating scale 2;

S2. The photoelectric sensor array 3 receives light, and outputs a high-level signal and a low-level signal according to whether it is blocked by the grating line;

S3. The high-speed voltage comparator 6 performs shaping and level conversion on the output level signal;

S4. The signal processing unit 4 receives the shaped and level-converted signal, detects the signal edge, judges the moving direction of the grating and counts it, and obtains the angular displacement value; the specific steps are:

S41. Assuming that the incremental circular grating ruler 2 moves clockwise relative to the photoelectric sensor, at the initial time 0, the distribution of the photoelectric sensor within the grating pitch and the corresponding output signal are shown in Figure 4;

S42. At moment 1 of the movement, the photoelectric sensor is blocked by the grating line, the unblocked photoelectric sensor outputs a high level, and the blocked photoelectric sensor outputs a low level. In this embodiment, for the convenience of detection, the signal is reversed, That is, the blocked sensor outputs a high level, otherwise it outputs a low level (the following descriptions shall prevail), as shown in Figure 5;

S43. Continue to move forward to time 2, 3, 4, 5, 6, 7, and the corresponding signals are shown in Fig. 6, Fig. 7, Fig. 8, Fig. 9, Fig. 10 and Fig. 11 respectively;

S44, utilize combinational logic to carry out direction judgment according to the characteristics of adjacent three photoelectric sensor output signals, the combined logic circuit is as shown in Figure 21; Assume that the output signals of photoelectric sensors 1, 2, 3 correspond to A, B, C respectively; In the case of clockwise motion, the direction of motion is As shown in Figure 12; on the contrary, if the grating ruler moves counterclockwise relative to the sensor, the signal output starts from the number n of the photoelectric sensor, and the moving direction is

S45. Assuming a sudden change of direction during the movement, the combination logic is also used to judge the direction, and the counterclockwise movement reaches the time 8, 9, 10, 11, 12, 13, and 14. The corresponding signals are shown in Figures 13, 14, 15, and 16, 17, 18, 19;

S46, the signal processing unit 4 utilizes the edge detection method to detect and count the pulse edge, and the required detection edge 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 displacement The calculation formula is: in, is the previous angular displacement value, ω is the angular displacement corresponding to a grating pitch, N is the number of sensors placed within a grating pitch, M is the number of counted pulses; when the grating moves counterclockwise,

S5. The angular displacement display unit 5 displays the displacement value processed by the signal processing unit 4 .

This embodiment has the advantages of simple structure, low detection cost, high measurement accuracy, fast detection speed and strong practicability.

The implementation examples described above are only preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. Therefore, all changes made according to the shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims (6)

1. An incremental circular grating ruler grating angular displacement detection system, characterized in that: comprising a parallel light source (1), an incremental circular grating ruler (2), a photoelectric sensor array (3), and a signal processing unit (4) , an angular displacement display unit (5) and a high-speed voltage comparator (6); wherein, the incremental circular grating scale (2) is perpendicular to the irradiation direction of the light source (1); the photoelectric sensor array (3) is placed on the incremental The circular grating scale (2) is within the grating pitch, and is evenly distributed in a stepped shape; the high-speed voltage comparator (6) is connected between the photoelectric sensor array (3) and the signal processing unit (4), and the photoelectric sensor array (3) The output signal is reshaped and the square wave signal obtained by reshaping is carried out level conversion; 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) on. 2. A kind of incremental circular grating scale grating angular displacement detection system according to claim 1, is characterized in that: the number n=(H-D)/(D+L)+1 of described photoelectric sensor; Misalignment angle x =(w-q)/(n-1); where, q is the angle corresponding to the nth photoelectric sensor, w is the angle between two grating lines; H is the length of the grid line; D is the length of the photoelectric sensor at the grid line The width in the direction; x is the misalignment angle of two adjacent photoelectric sensors in the rotation direction of the circular scale; L is the adjacent gap. 3. A method for detecting the angular displacement of the incremental circular grating ruler grating for the system according to claim 1, characterized in that: comprising the following steps: S1. The light emitted from the parallel light source shines on the incremental circular grating scale; S2. The photoelectric sensor array receives light, and outputs a high-level signal and a low-level signal according to whether it is blocked by the grating line; S3. The high-speed voltage comparator performs shaping and level conversion on the output level signal; S4. The signal processing unit receives the shaped and level-converted signal, detects the signal edge, judges the moving direction of the grating and counts it, and obtains the angular displacement value; S5. The angular displacement display unit displays the angular displacement value processed by the signal processing unit. 4. A kind of incremental circular grating ruler grating angular displacement detection method according to claim 3, is characterized in that: described signal processing unit utilizes edge detection method to carry out pulse edge detection and counting, and the required detection edge is pulse rising edge. 5. A kind of incremental circular grating ruler grating angular displacement detection method according to claim 3, is characterized in that: in described step S4, direction of motion utilizes combinational logic to output respectively according to adjacent three photoelectric sensors A, The characteristics of B and C are judged; in the case of clockwise movement, the direction of movement is In the case of counterclockwise movement, the direction of movement is 6. A kind of incremental circular grating ruler grating angular displacement detection method according to claim 3, is characterized in that: described grating angular displacement value calculation process is as follows: When the grating moves clockwise, the angular displacement The calculation formula is: in, is the previous angular displacement value, ω is the angular displacement corresponding to a grating pitch, N is the number of sensors placed within a grating pitch, M is the number of counted pulses; when the grating moves counterclockwise,