CN116734908A - Encoder chip offset response test system - Google Patents

Encoder chip offset response test system Download PDF

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Publication number
CN116734908A
CN116734908A CN202310696943.1A CN202310696943A CN116734908A CN 116734908 A CN116734908 A CN 116734908A CN 202310696943 A CN202310696943 A CN 202310696943A CN 116734908 A CN116734908 A CN 116734908A
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Prior art keywords
displacement
test
encoder chip
light source
detecting
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Inventor
王晓曦
张义荣
高朕
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Chuanzhou Semiconductor Technology Shanghai Co ltd
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Chuanzhou Semiconductor Technology Shanghai Co ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D18/00—Testing or calibrating apparatus or arrangements provided for in groups G01D1/00 - G01D15/00

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  • General Physics & Mathematics (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

The invention provides a encoder chip offset response test system, which comprises: the test machine comprises a fixed tool and a deviation generating device, and a test motor, a test light source and a code disc are arranged on the fixed tool; the code disc is connected with a rotating shaft of the test motor; a light hole is formed in the code disc; the deviation generating device is provided with an encoder chip and comprises a horizontal displacement table, a pitching displacement table and a rotating displacement table; the light of the test light source irradiates the encoder chip when passing through the light hole; the test circuit comprises a power supply and an oscilloscope; the oscilloscope is connected with the encoder chip to display response waveforms; the deviation detecting device is used for detecting the deviation value of the encoder chip and comprises a double-path interferometer for detecting horizontal displacement, an optical flow sensor for detecting rotary displacement and a distortion detecting camera for detecting pitching displacement. According to the encoder chip deviation response test system provided by the invention, the accuracy of the test result is improved by using the deviation detection equipment.

Description

Encoder chip offset response test system
Technical Field
The invention relates to the technical field of photoelectric testing, in particular to an encoder chip offset response testing system.
Background
The encoder chip is a chip for forming sine and cosine or square wave electric signals by the light source and the rotating code wheel, so the encoder chip can be tested by the two elements. The encoder chip position needs to be precisely aligned with the light source and the code wheel to output signals with excellent quality, so that when the encoder chip offset position is not matched, namely the position is not matched, the output signal quality is poor. Therefore, it is necessary to test the influence of encoder chip offset on the encoder chip output signal.
The invention patent with the application number of CN202211394312.6 and the name of an optical fiber low-stress clamping and aligning device for ultrahigh polarization extinction ratio generation in the prior art discloses an optical fiber low-stress clamping and aligning device for ultrahigh polarization extinction ratio generation, which comprises an optical fiber sample module, an adjustable magnetic clamping module, a binocular vision system module, a coaxial adjusting and aligning module and an angle rotating and measuring module, wherein: the optical fiber sample module comprises a first optical fiber sample and a second optical fiber sample; the optical fiber adjustable magnetic clamping module comprises a first adjustable magnetic clamp and a second adjustable magnetic clamp; the coaxial adjustment and alignment module comprises a first coaxial adjustment and alignment module and a second coaxial adjustment and alignment module; the binocular vision system module, the second coaxial adjusting and aligning module and the angle rotating and measuring module are fixed on the marble table. The device can realize extremely low stress clamping and precise coaxial alignment of the optical fiber, has the advantages of low clamping stress, high alignment precision, wide application range and the like, and can be used in the field of calibration of polarization extinction ratio test instruments. However, in the technical solution disclosed in this patent, the accuracy of the test result does not meet the requirements of the encoder chip.
Therefore, it is necessary to provide an encoder chip offset response test system to effectively solve the above-mentioned problems.
Disclosure of Invention
The invention provides a system for testing the deviation response of an encoder chip, which takes horizontal displacement, pitching displacement and rotating displacement of the encoder chip after the deviation is generated as deviation values, tests the influence of the horizontal displacement on the output signal of the encoder chip, acquires the horizontal displacement through a double-path interferometer, acquires the rotating displacement through an optical flow sensor, acquires the pitching displacement through a distortion detection camera, and improves the accuracy of test results.
The embodiment of the invention provides a system for testing the deviation response of an encoder chip, which comprises the following components:
the testing machine comprises a fixed tool and a deviation generating device;
the fixed tool is provided with a test motor, a test light source and a code disc; the code disc is connected with a rotating shaft of the test motor; a light hole is formed in the code disc, and the light rays of the test light source are allowed to pass through when the code disc rotates to the state that the light hole is opposite to the test light source;
the deviation generating device is provided with an encoder chip and comprises a horizontal displacement table, a pitching displacement table and a rotating displacement table which are used for respectively adjusting the horizontal displacement, the pitching displacement and the rotating displacement of the encoder chip; the light of the test light source irradiates the encoder chip when passing through the light hole;
the test circuit comprises a power supply and an oscilloscope, wherein the power supply supplies power to the test motor, the test light source and the encoder chip; the oscilloscope is connected with the encoder chip to display response waveforms;
the offset detection equipment is used for detecting the offset value of the encoder chip and comprises a double-path interferometer for detecting horizontal displacement, an optical flow sensor for detecting rotary displacement and a distortion detection camera for detecting pitching displacement.
Preferably, the horizontal displacement table is rectangular, and the side surface of the horizontal displacement table is plated with a reflective film; the double-path interferometer is provided with two paths of displacement detection interference light paths which are respectively used for detecting X-direction displacement and Y-direction displacement;
the displacement detection interference light path comprises a laser, a dichroic mirror and a photodiode, wherein a light beam emitted by the laser is divided into two paths of first light beams and second light beams which are vertically oscillated after passing through the dichroic mirror, the first light beams are vertically irradiated to the reflective film and then reflected to the dichroic mirror and then reflected to the photodiode, the second light beams are directly irradiated to the photodiode, the photodiode receives signals formed by the coherence of the first light beams and the second light beams, and displacement in the corresponding direction is calculated through the signals received by the photodiode.
Preferably, the X-direction displacement and the Y-direction displacement are calculated by the following formulas, respectively:
wherein N is X-direction displacement, M is Y-direction displacement,for detecting the initial phase of the photodiode displaced in the X-direction +.>To detect the displacement end phase lambda of the photodiode displaced in the X direction X An emission wavelength of the laser for detecting X-direction displacement;
for detecting the initial phase of the photodiode displaced in the Y direction +.>To detect the displacement end phase lambda of the photodiode displaced in the Y direction Y To detect the emission wavelength of the Y-direction displacement laser;
the horizontal displacement is calculated specifically by the following formula:
wherein R is horizontal displacement.
Preferably, the optical flow sensor comprises a detection light source and an image sensor, wherein the light of the detection light source irradiates the side surface of the rotary displacement table, and the image sensor captures the light reflected by the side surface of the rotary displacement table and records a two-dimensional image matrix; the rotary displacement table is cylindrical, and the side surface of the rotary displacement table is a rough surface, so that different two-dimensional image matrixes are formed on the image sensor when the rotary displacement table is at different angles; the rotational displacement is calculated by comparing the two-dimensional image matrix.
Preferably, the rotational displacement is calculated by the following formula:
wherein Theta is rotational displacement, k is the number of displacement pixels of the same element as the two-dimensional image matrix at the beginning of displacement and the two-dimensional image matrix at the end of displacement, s is the size of a pixel unit, and radii is the distance between the image sensor and the rotation axis of the rotational displacement table;
the number of shift pixels is specifically calculated by the following formula:
A＝IO(x，y)∩IE(x，y)
IO-A＝P 1 (c 1 ，d 1 )∪O(a，b)∪P(e 1 ，f 1 )
IE-A＝P 2 (c 2 ，d 2 )∪O(a，b)∪P(e 2 ，f 2 )
k＝MAX(e 2 -e 1 ，c 2 -c 1 )
wherein IO (x, y) is a two-dimensional image matrix at the beginning of displacement; IE (x, y) is a two-dimensional image matrix at the end of displacement; a, b are dimension parameters of matrix A, c 1 ，d 1 ，e 1 ，f 1 ，c 2 ，d 2 ，e 2 ，f 2 And the dimension parameters are all the dimension parameters solved by the matrix.
Preferably, the pitching displacement platform is rectangular, a standard grid is arranged at the bottom of the pitching displacement platform, and the intersection points of the standard grid form test points which are arranged at equal intervals in the transverse direction and the longitudinal direction, and the test points are used for reading coordinate data when the distortion detection camera shoots; and the distortion detection camera is arranged opposite to the bottom of the pitching displacement platform, and pitching displacement is calculated through the image of the standard grid shot by the distortion detection camera.
Preferably, the pitch displacement is calculated by the following formula:
Alpha＝cos- 1 (ava(ΔA n ))
wherein Alpha is pitch displacement, x n1 To the abscissa, x, of the test points at the end of the first row of grid in the image at the beginning of the displacement 1 The abscissa of the test point at the beginning of the first row of grids in the camera image at the beginning of displacement; x is x e1 For the abscissa, x, of the test points at the end of the first row of grid in the camera image at the end of the displacement 01 The abscissa of the test point at the beginning of the first row of grids in the camera image when the displacement is finished; for each row of test points, a delta A is calculated n N is the number of rows.
Preferably, the horizontal displacement platform, the rotary displacement platform and the pitching displacement platform of the deflection generating device are sequentially arranged from bottom to top, the encoder chip is arranged on a test PCB, and the test PCB is fixed on the pitching displacement platform.
Preferably, the fixed tooling comprises a measuring platform, a Z-axis travel table and a testing platform, wherein the bottom end of the Z-axis travel table is fixed on the measuring platform, the testing platform is movably arranged on the Z-axis travel table, and the height of the testing platform is adjustable; the test motor is arranged on the test platform, and the test light source is fixed on the test platform; the deviation generating device, the double-path interferometer, the optical flow sensor and the distortion detection camera are all arranged on the measuring platform.
Preferably, the test circuit further comprises an ammeter, the ammeter is connected with the test light source and used for measuring the current value of the test light source, and the test light source is an LED light source.
Compared with the prior art, the technical scheme of the embodiment of the invention has the following beneficial effects:
according to the encoder chip offset response test system provided by the embodiment of the invention, an offset generating device is arranged to realize the adjustment of horizontal displacement, pitching displacement and rotation displacement of the encoder chip; taking the horizontal displacement, pitching displacement and rotating displacement of the encoder chip after the deviation is generated as deviation values, testing the influence of the horizontal displacement, pitching displacement and rotating displacement on the output signal of the encoder chip, and having stronger testing correlation and more accurate result;
further, horizontal displacement is measured by a double-path interferometer, rotational displacement is measured by an optical flow sensor, pitching displacement is measured by a distortion detection camera, accuracy of a measurement result is improved, and accuracy of a test result is further improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the prior art, a brief description of the drawings is provided below, wherein it is apparent that the drawings in the following description are some, but not all, embodiments of the present invention. Other figures may be derived from these figures without inventive effort for a person of ordinary skill in the art.
FIG. 1 is a schematic diagram of a test machine of an encoder chip bias response test system according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a test circuit of an encoder chip bias response test system according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a dual-path interferometer measurement horizontal displacement of an encoder chip bias response test system according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of an encoder chip offset response test system for measuring rotational displacement using an optical flow sensor according to one embodiment of the present invention;
fig. 5 is a schematic diagram of measuring pitch displacement by a distortion detection camera of an encoder chip misalignment response testing system according to an embodiment of the present invention.
In the figure:
1. a test machine; 11. fixing the tool; 111. a measurement platform; 112. a Z-axis travel table; 113. a test platform; 12. a deviation generating device; 121. a horizontal displacement table; 1211. a reflective film; 122. a rotary displacement table; 123. a pitch displacement stage; 1231. a standard grid;
2. a test circuit; 21. testing a motor; 22. testing a light source; 23. a code wheel; 24. an encoder chip; 25. a power supply; 26. an oscilloscope; 27. an ammeter; 28. testing the PCB;
3. a deviation detecting device; 31. a two-way interferometer; 311. a laser; 312. a dichroic mirror; 313. a photodiode; 32. an optical flow sensor; 321. detecting a light source; 322. an image sensor; 33. a distortion detection camera.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The technical scheme of the invention is described in detail below by specific examples. The following embodiments may be combined with each other, and some embodiments may not be repeated for the same or similar concepts or processes.
Based on the problems existing in the prior art, the embodiment of the invention provides an encoder chip offset response test system, which takes horizontal displacement, pitching displacement and rotation displacement of an encoder chip after offset generation as offset values, tests the influence of the encoder chip on an output signal of the encoder chip, obtains the horizontal displacement through a double-path interferometer, obtains the rotation displacement through an optical flow sensor, obtains the pitching displacement through a distortion detection camera, and improves the accuracy of test results.
FIG. 1 is a schematic diagram of a test machine of an encoder chip bias response test system according to an embodiment of the present invention; FIG. 2 is a schematic diagram of a test circuit of an encoder chip bias response test system according to an embodiment of the present invention; FIG. 3 is a schematic diagram of a dual-path interferometer measurement horizontal displacement of an encoder chip bias response test system according to an embodiment of the present invention; FIG. 4 is a schematic diagram of an encoder chip offset response test system for measuring rotational displacement using an optical flow sensor according to one embodiment of the present invention; fig. 5 is a schematic diagram of measuring pitch displacement by a distortion detection camera of an encoder chip misalignment response testing system according to an embodiment of the present invention.
Referring now to fig. 1-5, an embodiment of the present invention provides an encoder chip offset response test system, including:
the test machine 1, the test machine 1 comprises a fixed tool 11 and a deviation generating device 12,
the fixed tooling 11 is provided with a test motor 21, a test light source 22 and a code wheel 23; the code wheel 23 is connected with the rotating shaft of the test motor 21; the code disc 23 is provided with a light hole, and when the code disc 23 rotates to the state that the light hole is opposite to the test light source 22, the light rays of the test light source 22 are allowed to pass through;
the encoder chip 24 is arranged on the offset generating device 12, and the offset generating device 12 comprises a horizontal displacement table 121, a pitching displacement table 123 and a rotating displacement table 122 for respectively adjusting the horizontal displacement, the pitching displacement and the rotating displacement of the encoder chip 24; the light of the test light source 22 is irradiated to the encoder chip 24 while passing through the light-transmitting hole;
in one embodiment, the horizontal displacement stage 121, the rotational displacement stage 122 and the pitch displacement stage 123 of the offset generating device 12 are sequentially arranged from bottom to top, the encoder chip 24 is disposed on the test PCB 28, and the test PCB 28 is fixed on the pitch displacement stage 123.
The test circuit 2, the test circuit 2 includes the test motor 21, test light source 22, encoder chip 24, power supply 25 and oscilloscope 26, the power supply 25 supplies power to the test motor 21, test light source 22 and encoder chip 24; the oscilloscope 26 is connected with the encoder chip 24 to display response waveforms;
in an embodiment, the test circuit 2 further includes an ammeter 27, the ammeter 27 is connected to the test light source 22 for measuring a current value of the test light source 22, the current value corresponds to a brightness of the test light source 22, and the test light source 22 is an LED light source.
The misalignment detecting apparatus 3 for detecting the misalignment value of the encoder chip 24 includes a two-way interferometer 31 that detects horizontal displacement, an optical flow sensor 32 that detects rotational displacement, and a distortion detecting camera 33 that detects pitch displacement.
In an embodiment, the fixed tooling 11 comprises a measuring platform 111, a Z-axis travel table 112 and a testing platform 113, wherein the bottom end of the Z-axis travel table 112 is fixed on the measuring platform 111, the testing platform 113 is movably arranged on the Z-axis travel table 112, and the height of the testing platform 113 is adjustable; the test motor 21 is mounted on the test platform 113, and the test light source 22 is fixed on the test platform 113; the misalignment generating apparatus 12, the two-way interferometer 31, the optical flow sensor 32, and the distortion detecting camera 33 are all provided to the measurement platform 111.
In practical implementation, the horizontal displacement table 121 is rectangular, and the side surface of the horizontal displacement table 121 is plated with a reflective film 1211; the dual interferometer 31 has two displacement detection interference light paths for detecting X-direction displacement and Y-direction displacement, respectively;
taking a displacement detection interference optical path for detecting displacement in the X direction as an example, the displacement detection interference optical path includes a laser 311, a dichroic mirror 312 and a photodiode (Pd) 313, a light beam emitted from the laser 311 is divided into two paths of a first light beam and a second light beam which are oscillated vertically after passing through the dichroic mirror 312, the first light beam is reflected to the dichroic mirror 312 after being irradiated perpendicularly to a reflective film 1211, and then is reflected to the photodiode 313, the second light beam is directly irradiated to the photodiode 313, the photodiode 313 receives a signal formed by coherent formation of the first light beam and the second light beam, and the displacement in the X direction is calculated by the signal received by the photodiode 313.
The displacement detection interference light path for detecting the displacement in the Y direction is similar to the displacement detection interference light path for detecting the displacement in the X direction, and will not be described here again.
Specifically, the X-direction displacement and the Y-direction displacement are calculated by the following formulas, respectively:
wherein N is X-direction displacement, M is Y-direction displacement,for detecting the initial phase of the photodiode 313 displaced in the X-direction +.>To detect the displacement end phase, lambda, of the photodiode 313 displaced in the X direction X The emission wavelength of the laser 311 for detecting X-direction displacement;
to detect the initial phase of the Y-direction displaced photodiode 313,/and>to detect the displacement end phase of the photodiode 313 displaced in the Y direction, lambda Y To detect the emission wavelength of the Y-direction displacement laser 311;
the horizontal displacement is calculated specifically by the following formula:
wherein R is horizontal displacement.
In a specific implementation, the optical flow sensor 32 includes a detection light source 321 and an image sensor 322, the detection light source 321 is an LED light source, the light of the detection light source 321 irradiates the side surface of the rotary displacement table 122, and the image sensor 322 captures the light reflected by the side surface of the rotary displacement table 122 and records a two-dimensional image matrix; the rotary displacement stage 122 is cylindrical, and the side surface of the rotary displacement stage 122 is a rough surface, so that different two-dimensional image matrixes are formed on the image sensor 322 when the rotary displacement stage 122 is at different angles; the rotational displacement is calculated by comparing the two-dimensional image matrices.
Specifically, the rotational displacement is calculated by the following formula:
where Theta is the rotational displacement, k is the number of displacement pixels of the same element as the two-dimensional image matrix at the beginning of the displacement and the two-dimensional image matrix at the end of the displacement, s is the size of the pixel cell, and radii is the distance between the image sensor 322 and the rotational axis of the rotational displacement stage 122;
the number of shift pixels is specifically calculated by the following formula:
A＝IO(x，y)∩IE(x，y)
IO-A＝P 1 (c 1 ，d 1 )∪O(a，b)∪P(e 1 ，f 1 )
IE-A＝P 2 (c 2 ，d 2 )∪O(a，b)∪P(e 2 ，f 2 )
k＝MAX(e 2 -e 1 ，c 2 -c 1 )
wherein IO (x, y) is a two-dimensional image matrix at the beginning of displacement; IE (x, y) is a two-dimensional image matrix at the end of displacement; a, b are dimension parameters of matrix A, c 1 ，d 1 ，e 1 ，f 1 ，c 2 ，d 2 ，e 2 ，f 2 Dimension all solved for matrixA degree parameter.
In a specific implementation, the pitching displacement platform 123 is rectangular, a standard grid 1231 is arranged at the bottom of the pitching displacement platform 123, and the intersection points of the standard grid 1231 form test points which are arranged at equal intervals in the transverse direction and the longitudinal direction, and the test points are used for reading coordinate data when the distortion detection camera 33 shoots; the distortion detection camera 33 is disposed opposite to the bottom of the pitch displacement stage 123, and pitch displacement is calculated from the image of the standard grid 1231 captured by the distortion detection camera 33.
Specifically, the pitch displacement is calculated by the following formula:
Alpha＝cos -1 (ava(ΔA n ))
wherein Alpha is pitch displacement, x n1 To the abscissa, x, of the test points at the end of the first row of grid in the image at the beginning of the displacement 1 The abscissa of the test point at the beginning of the first row of grids in the camera image at the beginning of displacement; x is x e1 For the abscissa, x, of the test points at the end of the first row of grid in the camera image at the end of the displacement 01 The abscissa of the test point at the beginning of the first row of grids in the camera image when the displacement is finished; for each row of test points, a delta A is calculated n N is the number of rows.
The following exemplifies the encoder chip offset response test system provided by the invention in actual test:
assuming that the encoder chip 24 is displaced only in the X direction, the phase before displacementAfter displacementWavelength lambda of the laser 311 used X By calculating the displacement of the encoder chip 24 in the X direction to n= 9370.03nm, =355 nm.
It is assumed that the encoder chip 24 is only rotatingDisplacement is generated in the direction, the radius distance radii=30 mm of the image sensor 322 relative to the rotation axis, the size s=1 of the pixel unit of the image sensor 322 u m, the two-dimensional image matrix IO captured by the image sensor 322 at the beginning of displacement is [0,1,0,; 0,1, 0;0,1, 0;0,1, 0;0,1,0,0,0]The two-dimensional image matrix IE captured by the image sensor 322 at the beginning of displacement is [0,0,0,0,1;0,0,0,0,1;0,0,0,0,1;0,0,0,0,1;0,0,0,0,1]The method comprises the steps of carrying out a first treatment on the surface of the The number of shift pixels k=3 can be found according to an algorithm, and the rotational shift theta=0.0057°.
Assuming that the encoder chip 24 is displaced only in the pitch direction, the standard grid of the pitch displacement stage 123 has 4 test points falling respectively at (1, 1), (-1, 1), (1, -1), (-1, -1); after the displacement, 4 test points fall at (1.5,1.2) (-0.2, 0.5) (-0.2, -0.5), (1.5, -1.2); then
ΔA1＝(1.5-(-0.2))/(1-(-1))＝0.85；
ΔA2＝(1.5-(-0.2))/(1-(-1))＝0.85；
Alpha＝31.78°。
As can be seen from the test data which are exemplified in the actual test, the encoder chip deviation response test system provided by the invention improves the accuracy of the test result by using the deviation detection equipment.
In summary, in the encoder chip offset response test system provided by the embodiment of the invention, the offset generating device 12 is provided to realize the adjustment of the horizontal displacement, the pitch displacement and the rotation displacement of the encoder chip 24; taking the horizontal displacement, the pitching displacement and the rotating displacement of the encoder chip 24 after the deviation is generated as deviation values, testing the influence of the horizontal displacement, the pitching displacement and the rotating displacement on the output signal of the encoder chip 24, and having stronger testing correlation and more accurate result;
further, the horizontal displacement is measured by the dual-path interferometer 31, the rotational displacement is measured by the optical flow sensor 32, the pitch displacement is measured by the distortion detection camera 33, the accuracy of the measurement result is improved, and the accuracy of the test result is further improved.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.

Claims (10)

1. An encoder chip offset response test system, comprising:
the testing machine comprises a fixed tool and a deviation generating device;
the fixed tool is provided with a test motor, a test light source and a code disc; the code disc is connected with a rotating shaft of the test motor; a light hole is formed in the code disc, and the light rays of the test light source are allowed to pass through when the code disc rotates to the state that the light hole is opposite to the test light source;
the deviation generating device is provided with an encoder chip and comprises a horizontal displacement table, a pitching displacement table and a rotating displacement table which are used for respectively adjusting the horizontal displacement, the pitching displacement and the rotating displacement of the encoder chip; the light of the test light source irradiates the encoder chip when passing through the light hole;
the test circuit comprises a power supply and an oscilloscope, wherein the power supply supplies power to the test motor, the test light source and the encoder chip; the oscilloscope is connected with the encoder chip to display response waveforms;
the offset detection equipment is used for detecting the offset value of the encoder chip and comprises a double-path interferometer for detecting horizontal displacement, an optical flow sensor for detecting rotary displacement and a distortion detection camera for detecting pitching displacement.
2. The encoder chip offset response test system of claim 1, wherein the horizontal displacement table is rectangular, and a side surface of the horizontal displacement table is plated with a reflective film; the double-path interferometer is provided with two paths of displacement detection interference light paths which are respectively used for detecting X-direction displacement and Y-direction displacement;
the displacement detection interference light path comprises a laser, a dichroic mirror and a photodiode, wherein a light beam emitted by the laser is divided into two paths of first light beams and second light beams which are vertically oscillated after passing through the dichroic mirror, the first light beams are vertically irradiated to the reflective film and then reflected to the dichroic mirror and then reflected to the photodiode, the second light beams are directly irradiated to the photodiode, the photodiode receives signals formed by the coherence of the first light beams and the second light beams, and displacement in the corresponding direction is calculated through the signals received by the photodiode.
3. The encoder chip offset response test system of claim 2, wherein the X-direction displacement and the Y-direction displacement are each calculated by the following formula:
wherein N is X-direction displacement, M is Y-direction displacement,for detecting the initial phase of the photodiode displaced in the X-direction +.>To detect the displacement end phase lambda of the photodiode displaced in the X direction X An emission wavelength of the laser for detecting X-direction displacement;
for detecting the initial phase of the photodiode displaced in the Y direction +.>To detect the displacement end phase lambda of the photodiode displaced in the Y direction Y To detect the emission wavelength of the Y-direction displacement laser;
the horizontal displacement is calculated specifically by the following formula:
wherein R is horizontal displacement.
4. The encoder chip misalignment response testing system of claim 1 wherein the optical flow sensor comprises a detection light source that irradiates the side of the rotary displacement stage with light and an image sensor that captures light reflected back from the side of the rotary displacement stage and records a two-dimensional image matrix; the rotary displacement table is cylindrical, and the side surface of the rotary displacement table is a rough surface, so that different two-dimensional image matrixes are formed on the image sensor when the rotary displacement table is at different angles; the rotational displacement is calculated by comparing the two-dimensional image matrix.
5. The encoder chip offset response test system of claim 4, wherein the rotational displacement is calculated by the following formula:
wherein Theta is rotational displacement, k is the number of displacement pixels of the same element as the two-dimensional image matrix at the beginning of displacement and the two-dimensional image matrix at the end of displacement, s is the size of a pixel unit, and radii is the distance between the image sensor and the rotation axis of the rotational displacement table;
the number of shift pixels is specifically calculated by the following formula:
A＝IO(x，y)∩IE(x，y)
IO-A＝P 1 (c 1 ，d 1 )∪O(a，b)∪P(e 1 ，f 1 )
IE-A＝P 2 (c 2 ，d 2 )∪O(a，b)∪P(e 2 ，f 2 )
k＝MAX(e 2 -e，c 2 -c 1 )
wherein IO (x, y) is a two-dimensional image matrix at the beginning of displacement; IE (x, y) is a two-dimensional image matrix at the end of displacement; a, b are dimension parameters of matrix A, c 1 ,d 1 ,e 1 ,f 1 ,c 2 ,d 2 ,e 2 ,f 2 And the dimension parameters are all the dimension parameters solved by the matrix.
6. The encoder chip offset response test system according to claim 1, wherein the pitching displacement platform is rectangular, a standard grid is arranged at the bottom of the pitching displacement platform, and intersecting points of the standard grid form test points which are arranged at equal intervals in the transverse direction and the longitudinal direction, and the test points are used for reading coordinate data when the distortion detection camera shoots; and the distortion detection camera is arranged opposite to the bottom of the pitching displacement platform, and pitching displacement is calculated through the image of the standard grid shot by the distortion detection camera.
7. The encoder chip offset response test system of claim 6, wherein the pitch displacement is calculated by the following formula:
Alpha＝cos -1 (ava(ΔA n ))
wherein Alpha is pitch displacement, x n1 To the abscissa, x, of the test points at the end of the first row of grid in the image at the beginning of the displacement 1 The abscissa of the test point at the beginning of the first row of grids in the camera image at the beginning of displacement; x is x e1 For the abscissa, x, of the test points at the end of the first row of grid in the camera image at the end of the displacement 01 The abscissa of the test point at the beginning of the first row of grids in the camera image when the displacement is finished; for each row of test points, a delta A is calculated n N is the number of rows.
8. The encoder chip offset response test system of claim 1, wherein the horizontal displacement stage, the rotational displacement stage, and the pitch displacement stage of the offset generating device are sequentially disposed from bottom to top, the encoder chip is disposed on a test PCB, and the test PCB is fixed on the pitch displacement stage.
9. The encoder chip offset response test system of claim 1, wherein the fixed tooling comprises a measurement platform, a Z-axis travel table and a test platform, wherein the bottom end of the Z-axis travel table is fixed on the measurement platform, the test platform is movably arranged on the Z-axis travel table, and the height of the test platform is adjustable; the test motor is arranged on the test platform, and the test light source is fixed on the test platform; the deviation generating device, the double-path interferometer, the optical flow sensor and the distortion detection camera are all arranged on the measuring platform.
10. The encoder chip offset response test system of claim 1, wherein the test circuit further comprises an ammeter connected to the test light source for measuring the current value of the test light source, the test light source being an LED light source.
CN202310696943.1A 2023-06-13 2023-06-13 Encoder chip offset response test system Pending CN116734908A (en)

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