Photoelectric encoder rotation angle dynamic precision detection method

Abstract

The invention discloses a method for detecting the rotating angle dynamic precision of a photoelectric encoder, and belongs to the technical field of angle measurement of photoelectric encoders. The method comprises the following steps of: coaxially installing a polyhedral prism, a tested photoelectric encoder and a direct current motor by using couplings, and rotating at a constant speed; the light emitting diode emits light to the multi-face prism, the light is received by the phototriode after being reflected by the multi-face prism, the phototriode outputs a trigger signal according to the photoelectric conversion principle, and the photoelectric encoder outputs the current angle after receiving the trigger signal. The difference between each output angle and the last output angle is compared with the rotation angle between the two received light rays of the polyhedral prism, and the dynamic precision of the photoelectric encoder can be obtained through calculation. The problem that the dynamic precision of the photoelectric encoder cannot be detected is solved, and the detection method of the photoelectric encoder is more perfect.

Description

Technical Field

[0001] The present invention belongs to the technical field of angle measurement of photoelectric encoders, and relates to a method for detecting the dynamic accuracy of the rotation angle of a photoelectric encoder. Background Art

[0002] With the progress of science and technology, people have higher and higher requirements for the control of angles and positions in the fields of industry, transportation, aerospace, instrumentation and other fields. From the previous control range of degrees and meters, it has gradually developed to the control of arcseconds and micrometers, and requirements for the real-time nature of control have also been put forward. Under such strong background requirements, the photoelectric encoder, as a key sensing device that converts mechanical displacement into an electrical signal to achieve precise measurement and control, has emerged as the times require. It is basically composed of a light source, a grating code disk, and a photosensitive device. Photoelectric encoders are divided into incremental encoders and absolute encoders, and their working principles are that the light-emitting device emits light through the engraved lines or holes on the code disk, which is received by the photosensitive device to generate an electrical signal. After subsequent processing, the angle or position information is output.

[0003] As a key sensing device for high-precision angle or position measurement, the accuracy detection method of the photoelectric encoder is particularly important. The commonly used accuracy detection of photoelectric encoders usually obtains the output angle by comparing it with a standard calibration device after the photoelectric encoder rotates to a specific angle and stops. The detected accuracy is static accuracy. For example, a multi-faceted prism is coaxially connected to the photoelectric encoder to be tested, and the two are driven to rotate to the position to be detected by a fine-tuning device. Then, the rotation angle of the multi-faceted prism is measured by an autocollimator to calibrate the accuracy of the photoelectric encoder to be tested. The multi-faceted prism has a high-precision angle reference, and the autocollimator can accurately measure angles.

[0004] Dynamic accuracy refers to the error between the angle output when the encoder rotates and the standard angle. The dynamic accuracy can reflect the accuracy index of the photoelectric encoder during movement. According to this method, during detection, the dynamic accuracy can be measured according to the rotation speed of the actual application environment of the photoelectric encoder, and the measured result can reflect the performance index under the actual application conditions. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a method for detecting the dynamic accuracy of the rotation angle of a photoelectric encoder, which improves the detection method of the photoelectric encoder and the performance index of the photoelectric encoder.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for detecting the dynamic accuracy of the rotation angle of a photoelectric encoder includes the following steps;

[0008] Step S1, coaxially install the multi-faceted prism, the photoelectric encoder to be measured, and the DC motor from top to bottom;

[0009] Step S2: The concave center of the test fixture is installed at a preset distance from the central axis of the multi-faceted prism. Taking the center of the upper end face of the multi-faceted prism as the origin, the light-emitting diode and the photosensitive triode are installed on both sides of the test fixture.

[0010] Step S3: Start the DC motor to rotate in a certain direction at a constant speed, driving the measured optical encoder and the multi-faceted prism to rotate coaxially and uniformly.

[0011] Step S4: The multi-faceted prism rotates uniformly around the Z-axis. Whenever the center of the mirror surface rotates to the Y-axis, the light emitted by the light-emitting diode is received by the photosensitive triode.

[0012] Step S5: The photosensitive triode converts the received optical signal into an electrical signal, transmits it to the backend processing circuit to obtain a trigger signal, and sends the trigger signal to the measured optical encoder.

[0013] Step S6: After receiving the trigger signal, the measured optical encoder latches the current track signal, and outputs the current first angle value after signal processing ;

[0014] Step S7: When the multi-faceted prism rotates one face, steps S4 - S6 are executed again, and the second angle value output by the measured optical encoder is recorded , and calculate the current rotation angle dynamic accuracy of the measured optical encoder as ;

[0015] Step S8: Start the DC motor to rotate forward and backward one week respectively. According to steps S4 - S7, record the rotation angle dynamic accuracy obtained each time, and calculate the forward rotation angle dynamic accuracy and the reverse rotation angle dynamic accuracy respectively based on multiple groups of rotation data.

[0016] The beneficial effects of the present invention are as follows:

[0017] (1) By coaxially installing the standard multi-faceted prism and the measured optical encoder, the axial runout error during the rotation of the measured optical encoder can be offset, thereby reducing the influence on the rotation angle accuracy of the measured optical encoder in error analysis;

[0018] (2) Due to the method of using a standard multi-faceted prism for detection, the multi-faceted prism itself is a high-precision angle standard instrument with the characteristics of high precision and multi-functionality, so it can be used as a standard instrument to calibrate and detect the rotation angle accuracy of the optical encoder.

[0019] (3) Using the paired use of a light-emitting diode and a photosensitive triode as the trigger signal of the measured optical encoder, under the single-mirror reflection of the high-precision multi-faceted prism, the assembly position error between the detection components can be reduced, thereby ensuring the accuracy of the rotation angle accuracy of the measured optical encoder. Description of the Drawings

[0020] Figure 1 It is a coaxial installation position diagram of a standard multi-faceted prism and the photoelectric encoder to be measured.

[0021] Figure 2 It is a schematic optical path diagram of the dynamic detection method.

[0022] Figure 3 It is an installation position diagram of a standard multi-faceted prism, a light-emitting diode and a photosensitive triode.

[0023] Figure 4 It is a schematic circuit diagram of the trigger signal to the processing board.

[0024] Figure 5 It is a schematic diagram of the output angle data after the photoelectric encoder receives the trigger signal.

[0025] Reference numerals:

[0026] Multi-faceted prism 1, photoelectric encoder 2, coupling 3, DC motor 4, light-emitting diode 5, photosensitive triode 6, test fixture 7, reflected light 8, threshold voltage generator 9, comparator 10, trigger signal 11, angle data 12, external acquisition system 13. Specific implementation mode

[0027] The present invention will be further described below in conjunction with the drawings and embodiments.

[0028] The present invention provides a method for detecting the dynamic accuracy of the rotation angle of a photoelectric encoder, and the method includes the following steps:

[0029] Step S1, as Figure 1 shown, the lower end of the rotating shaft of the photoelectric encoder 2 to be measured is installed at the rotating shaft end of the DC motor 4 through the coupling 3, and then the multi-faceted prism 1 is fixedly connected to the upper end of the rotating shaft of the photoelectric encoder 2 to be measured through a fixture;

[0030] Step S2, as Figures 1 - 3 shown, the upper end surface of the multi-faceted prism 1 is flush with the upper end surface of the test fixture 7. The test fixture 7 is L-shaped, and the center of the L-shaped concave of the test fixture 7 is installed at a certain distance from the central axis of the multi-faceted prism 1. Taking the center of the upper end surface of a single mirror surface of the multi-faceted prism 1 as the origin, the light-emitting diode 5 and the photosensitive triode 6 are installed on both sides of the test fixture 7 through external structural members, and their positions are symmetrically installed with respect to the Y axis in the XY plane and are at the same height on the Z axis;

[0031] Step S3, start the DC motor 4 to rotate in a certain direction at a constant speed, and the coupling 3 drives the photoelectric encoder 2 to be measured and the multi-faceted prism 1 to rotate coaxially and uniformly;

[0032] Step S4: The multi-faceted prism 1 rotates uniformly around the Z-axis. Whenever the center of a single mirror surface of the multi-faceted prism 1 rotates to the Y-axis, the light emitted by the light-emitting diode 5 is received by the photosensitive triode 6.

[0033] Step S5: The photosensitive triode 6 converts the received optical signal into an electrical signal, transmits it to the backend processing circuit to obtain a trigger signal, and the backend processing circuit transmits the trigger signal to the measured optoelectronic encoder 2.

[0034] Step S6: After receiving the trigger signal, the measured optoelectronic encoder 2 latches the current track signal, and outputs the current first angle value after signal processing ;

[0035] Step S7: Rotate one face of the multi-faceted prism 1, and execute Step S4 - Step S6 again. Record the second angle value output by the measured optoelectronic encoder 2 and the corresponding standard angle value of rotating one face of the multi-faceted prism 1 , substitute into the formula , to obtain the current rotation angle dynamic accuracy of the measured optoelectronic encoder 2 for rotating one face of the multi-faceted prism 1.

[0036] Step S8: Start the DC motor 4 to rotate forward one week. According to Step S4 - Step S7, record the output angle value of the measured optoelectronic encoder 2 each time one face of the multi-faceted prism 1 rotates, and calculate the difference between the subtraction of the latter and the former of these angle values and the standard value of the polyhedron rotation angle . During this one week, record n groups of data. According to the formula obtain the forward rotation angle dynamic accuracy of the measured optoelectronic encoder 2 , then reverse one week. Based on a similar process and principle, calculate the reverse rotation angle dynamic accuracy .

[0037] In Step S1, the multi-faceted prism 1, the measured optoelectronic encoder 2, and the DC motor 4 are coaxially installed, reducing the error of the axial movement of the measured optoelectronic encoder 2 in the measurement method, thereby reducing the influence on the rotation angle accuracy of the measured optoelectronic encoder in error analysis.

[0038] In Step S2, as Figure 3 shown, the light-emitting diode 5 and the photosensitive triode 6 use the line perpendicular to the single mirror surface center Y-direction of the multi-faceted prism 1 as the normal, and the included angle between the emitted light and the received light in the XY plane is 90°.

[0039] In Step S4, the multi-faceted prism 1 is a high-precision angle standard instrument, used as the positioning reference for the angle.

[0040] In step S5, the photosensitive triode 6 is used for photoelectric conversion and outputting an electrical signal. After the electrical signal is compared with the threshold voltage by a comparator and then shaped and output, the backend processing circuit determines that the shaped and output electrical signal is a trigger signal. As Figure 4 shown, after the photosensitive triode 6 receives the reflected light 8 of the polyhedron edge 1, it immediately generates an electrical signal. This signal is compared with the threshold voltage generated by the threshold voltage generator 9 in the comparator 10, and a square wave trigger signal 11 is obtained and transmitted to the optical encoder 2. Among them, when the electrical signal is greater than the threshold voltage, the comparator 10 considers that a valid trigger signal 11 is generated.

[0041] In step S6, after the optical encoder 2 locks the current track signal using the rising or falling edge of the trigger signal, it starts to process.

[0042] In step S8, calculate the difference between the output angles of the optical encoder 2 for two adjacent times and the corresponding difference in the rotation angle of the polyhedron 1 during forward and reverse rotations;

[0043] As Figure 5 shown, after the optical encoder 2 receives the rising or falling edge of the trigger signal 11, it locks the current track signal, processes it and outputs the current angle data 12, which is stored in the external acquisition system 13. The difference between the two acquired angle values is read in the external acquisition system 13 and compared with the rotation angle value of the polyhedron 1 to obtain the dynamic accuracy of the rotation angle of the optical encoder 2.

[0044] The present invention provides a method for detecting the dynamic accuracy of the rotation angle of an optical encoder, improving the detection method of the optical encoder and the performance indicators of the optical encoder.

[0045] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for detecting the dynamic accuracy of the rotation angle of a photoelectric encoder, characterized in that: The steps include: Step S1, coaxially installing the polyhedron (1), the photoelectric encoder to be tested (2) and the DC motor (4) from top to bottom; Step S2, the concave center of the test fixture (7) is installed at a preset distance from the central axis of the polyhedral prism (1), and the light-emitting diode (5) and the phototransistor (6) are installed on both sides of the test fixture (7) with the center of the upper end surface of the polyhedral prism (1) as the origin; Step S3, starting the DC motor (4) to rotate at a constant speed in a certain direction, driving the photoelectric encoder (2) to be tested and the polyhedral prism (1) to rotate coaxially at a constant speed; Step S4, the polyhedron (1) rotates at a constant speed around the Z axis, and whenever the center of the mirror rotates to the Y axis, the light emitted by the light-emitting diode (5) is received by the phototransistor (6); Step S5, the phototransistor (6) converts the received optical signal into an electrical signal, transmits the electrical signal to the back-end processing circuit to obtain a trigger signal, and transmits the trigger signal to the photoelectric encoder (2) under test; Step S6: After receiving the trigger signal, the photoelectric encoder (2) under test latches the current code channel signal and outputs the current first angle value after signal processing. ; Step S7, when the polyhedron (1) rotates one face, steps S4 to S6 are executed again to record the second angle value output by the photoelectric encoder (2) under test , calculate the current dynamic accuracy of the measured photoelectric encoder (2) as ; Step S8, starting the DC motor (4) to rotate forward and reverse one circle each, and recording the rotation angle dynamic accuracy obtained each time according to steps S4 to S7, and calculating the forward rotation angle dynamic accuracy and the reverse rotation angle dynamic accuracy based on multiple sets of rotation data.

2. A method for detecting the dynamic accuracy of a photoelectric encoder angle according to claim 1, characterized in that: In the step S1, the lower end of the rotating shaft of the photoelectric encoder (2) to be tested is mounted on the rotating shaft end of the DC motor (4) via a coupling (3), and then the polyhedral prism (1) is fixedly connected to the upper end of the rotating shaft of the photoelectric encoder (2) to be tested via a tool.

3. The method for detecting the dynamic accuracy of the rotation angle of a photoelectric encoder according to claim 1, characterized in that: In step S2, the upper end surface of the polyhedral prism (1) is flush with the upper end surface of the test fixture (7), and the light-emitting diode (5) and the phototransistor (6) are installed symmetrically about the Y axis in the XY plane, and the distance between the two is the same on the Z axis.

4. A method for detecting the dynamic accuracy of the rotation angle of a photoelectric encoder according to claim 3, characterized in that: In the step, the light emitting diode (5) and the photosensitive triode (6) use a line perpendicular to the Y direction of the center of the single mirror surface of the polyhedral prism (1) as a normal, and the angle between the light emitting light and the light receiving light in the XY plane is 90°.

5. The method for detecting the dynamic accuracy of the rotation angle of a photoelectric encoder according to claim 3, characterized in that: The polyhedron (1) is used as a positioning reference for an angle.

6. A method for detecting the dynamic accuracy of a photoelectric encoder angle according to claim 1, characterized in that: In step S5, the phototransistor (6) performs photoelectric conversion to output an electrical signal, the electrical signal is compared with a threshold voltage by a comparator and then shaped and output, and the back-end processing circuit determines that the shaped output electrical signal is a trigger signal.

7. A method for detecting the dynamic accuracy of the rotation angle of a photoelectric encoder according to claim 6, characterized in that: When the electrical signal is greater than the threshold voltage, the comparator considers that a valid trigger signal is generated.

8. The method for detecting the dynamic accuracy of the rotation angle of a photoelectric encoder according to claim 1, characterized in that: In step S7, the standard angle value of the rotation of one face of the polyhedron (1) is denoted as a, and the current rotation angle dynamic accuracy of the photoelectric encoder (2) under test is .

9. A method for detecting the dynamic accuracy of the rotation angle of a photoelectric encoder according to claim 8, characterized in that: In step S8, the motor is started to rotate in the forward direction for one circle, and the angle value of the photoelectric encoder (2) under test is recorded each time a face of the polyhedron (1) is rotated, for a total of n sets of data, according to the formula The forward rotation angle dynamic accuracy of the photoelectric encoder (2) is obtained respectively , then start the motor to rotate in the opposite direction for one circle, and calculate the dynamic accuracy of the reverse rotation angle ,in It is the dynamic accuracy of the turning angle corresponding to each set of data.

10. A method for detecting the dynamic accuracy of a photoelectric encoder angle according to claim 6, characterized in that: The back-end processing circuit uses the rising edge or falling edge of the trigger signal to determine the trigger.

Images