Method for correcting eccentric position of encoder

Abstract

The application discloses a method for calculating and correcting eccentric position of an encoder. The method comprises the following steps: obtaining the difference between the angle position of a circular grating in at least one rotation period of a rotating member and the angle position of the rotating member under standard conditions; obtaining the difference between the maximum difference and the minimum difference in the difference, and the difference between the angle corresponding to the first maximum difference and the angle corresponding to the zero position of the circular grating after the zero position of the circular grating appears; obtaining the relative distance between the center of the circular grating and the rotation center of the rotating member according to the difference between the maximum difference and the minimum difference and the radius of the circular grating; obtaining the relative position between the center of the circular grating and the center of the rotating member according to the difference between the angle corresponding to the first maximum difference and the angle corresponding to the zero position signal; and adjusting the relative position of the center of the circular grating relative to the rotation center of the rotating member according to the relative distance and the relative position.

Description

Technical Field

[0001] This invention relates to the field of angle measurement technology, and more specifically, to a method for calculating and correcting the eccentric position of an encoder. Background Technology

[0002] An optical encoder is a sensing device used to measure the rotational displacement of an object. An optical encoder mainly consists of a circular grating and an observation probe. The circular grating is fixedly connected to the object being measured and rotates with it. The observation probe is located outside the circular grating. The outer surface of the circular grating has graduations. The observation probe reads the graduations on the circular grating. Therefore, the concentricity of the circular grating and the rotation center of the object directly affects the measurement accuracy of the optical encoder. Obtaining and adjusting the eccentric position of the circular grating is crucial for the installation of the optical encoder.

[0003] Existing methods for correcting the eccentricity of optical encoders typically employ external measuring elements, such as micrometers, microscopes, or laser interferometers. The eccentricity of the circular grating is determined using these external measuring elements, and the position of the central grating is adjusted accordingly. This method relies on external measuring elements, resulting in a complex correction process.

[0004] The size of the grating encoder is very small, usually less than 1 mm, making it difficult for external measuring elements to accurately measure the eccentricity distance of the grating encoder.

[0005] Furthermore, the accuracy of the eccentricity calculation and correction method is insufficient due to limitations in the measurement accuracy of external measuring elements. Therefore, a new technical solution is needed to address the aforementioned technical problems. Summary of the Invention

[0006] One objective of this disclosure is to provide a new technical solution for calculating and correcting the eccentric position of an encoder.

[0007] In one embodiment of this disclosure, a method for calculating and correcting the eccentric position of an encoder is provided. The method includes:

[0008] The difference between the angular position of the circular grating and the angular position of the rotating component under standard conditions is obtained during at least one rotation cycle of the rotating component;

[0009] Obtain the difference between the maximum and minimum differences among the differences, and the difference between the angle corresponding to the first maximum difference and the angle corresponding to the zero position after the zero position of the circular grating appears;

[0010] The relative distance between the center of the circular grating and the rotation center of the rotating component is obtained based on the sum of the absolute values ​​and the radius of the circular grating.

[0011] The relative orientation of the center of the circular grating and the rotation center of the rotating component is obtained based on the difference between the angle corresponding to the first maximum difference and the angle corresponding to the zero position signal.

[0012] The relative position of the center of the circular grating with respect to the rotation center of the rotating component is adjusted according to the relative distance and the relative orientation.

[0013] Optionally, among the differences obtained from the maximum and minimum differences, and the differences between the angle corresponding to the first maximum difference and the angle corresponding to the zero-position signal after the occurrence of the zero-position signal of the circular grating,

[0014] By generating a curve showing the difference between the angular position of the circular grating and the angular position of the rotating component under standard conditions within at least one rotation cycle of the rotating component, relative to the position of the circular grating, the difference between the maximum and minimum differences, and the difference between the angle corresponding to the first maximum difference and the angle corresponding to the zero-position signal are obtained; or

[0015] By generating a curve of the difference between the angular position of the circular grating and the angular position of the rotating component under standard conditions within at least one rotation cycle of the rotating component, relative to the standard position, the difference between the maximum difference and the minimum difference, as well as the difference between the angle corresponding to the first maximum difference and the angle corresponding to the zero position signal, are obtained.

[0016] Optionally, the angular position of the rotating component under standard conditions is calibrated using a high-precision encoder, the measurement accuracy of which is greater than that of the circular grating, or

[0017] The angular position of the rotating component under standard conditions is the angular position of the rotating component rotating at a constant speed.

[0018] Optionally, the rotating component rotates at a constant speed or at a variable speed.

[0019] Optionally, the rotating component rotates for at least two cycles.

[0020] Optionally, the encoder further includes an observation probe configured to acquire the angle of the circular grating, wherein, in the initial state, the zero position of the circular grating is opposite to the observation probe.

[0021] Alternatively, the relative distance can be obtained using the following formula:

[0022] r = 2π * A * R / 1296000

[0023] Where r: relative distance; A: the difference between the maximum and minimum differences; R: the radius of the circular grating.

[0024] Alternatively, the relative orientation can be obtained using the following formula:

[0025] θ = 90 + B

[0026] Wherein, θ: relative orientation; B: the difference between the angle corresponding to the first maximum difference after the zero-position signal of the circular grating appears and the angle corresponding to the zero-position signal.

[0027] Optionally, in adjusting the relative position of the center of the circular grating with respect to the center of the rotating member based on the relative distance and the relative orientation,

[0028] The displacements that the circular grating should be adjusted in the X and Y axes are obtained by triangulation.

[0029] Optionally, it further includes: determining whether the coincidence degree between the center of the circular grating and the rotation center of the rotating member reaches a set value; if not, performing the step of obtaining the difference between the maximum and minimum difference values ​​among the differences.

[0030] In one embodiment of this disclosure, the position correction method does not require measurement by external measuring elements. The relative position of the center of the circular grating with respect to the rotation center of the rotating component is calculated using rotation information read from the encoder itself, thus providing a basis for position correction of the circular grating center. This makes position correction of the circular grating easy and highly accurate. Attached Figure Description

[0031] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the invention and, together with their description, serve to explain the principles of the invention.

[0032] Figure 1 This is a flowchart of a position correction method according to an embodiment of the present disclosure.

[0033] Figure 2 This is an assembly diagram of a grating encoder according to an embodiment of the present disclosure.

[0034] Figure 3 This is an assembly diagram of a grating encoder from another angle according to an embodiment of the present disclosure.

[0035] Figure 4 This is a schematic diagram of the position correction method according to an embodiment of the present disclosure.

[0036] Figure 5 This is a curve showing the error of the position correction method according to an embodiment of the present disclosure as a function of the position of the circular grating.

[0037] Figure 6 This is a comparison of the error curves before and after position correction according to the embodiments of this disclosure, as a function of the circular grating position.

[0038] Figure 7 This is a schematic diagram of another encoder according to an embodiment of the present disclosure.

[0039] Figure 8 This is a comparison of the position correction error curves before and after the position correction according to another embodiment of the present disclosure, as a function of the circular grating position.

[0040] Explanation of reference numerals in the attached figures:

[0041] 101. Observation probe; 102. Circular grating; 1021. Zero-position graduation line; 1022. Grating line; 200. Rotating component. Detailed Implementation

[0042] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0043] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0044] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0045] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0046] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0047] According to one embodiment of this disclosure, an encoder position correction method is provided. For example... Figures 1-8 As shown, the encoder is used to measure the rotational motion of the rotating part 200. The encoder can be, but is not limited to, an optical encoder, a magnetic encoder, a capacitive encoder, a ball encoder, an inductive synchronizer, or a time encoder.

[0048] like Figure 1 As shown, the position correction method includes:

[0049] S11. Obtain the difference between the angular position of the circular grating 102 and the angular position of the rotating component 200 under standard conditions within at least one rotation cycle of the rotating component 200.

[0050] S12. Obtain the difference between the maximum and minimum differences among the differences, and the difference between the angle corresponding to the first maximum difference and the angle corresponding to the zero position after the zero position of the circular grating 102 appears.

[0051] S13. Based on the difference between the maximum and minimum differences and the radius of the circular grating 102, the relative distance between the center of the circular grating 102 and the rotation center of the rotating member 200 is obtained.

[0052] S14. Based on the difference between the angle corresponding to the first maximum difference and the angle corresponding to the zero position signal, the relative orientation between the center of the circular grating 102 and the rotation center of the rotating member 200 is obtained.

[0053] S15. Adjust the relative position of the center of the circular grating 102 with respect to the rotation center of the rotating member 200 according to the relative distance and the relative orientation.

[0054] Take a grating encoder as an example. The grating encoder includes an observation probe 101 and a circular grating 102. The observation probe 101 is disposed outside the circular grating 102. For example, as... Figure 2 As shown, a plurality of scribe lines 1022 are evenly arranged on the outer wall of the circular grating 102. The number of scribe lines around the grating 102 is 360, 3600, or 36000. The observation probe 101 is located on the side of the circular grating 102. Alternatively, it could be as follows: Figure 7 , Figure 8 As shown, scribe lines 1022 are provided on the upper or lower surface of the circular grating 102. The observation probe is located above or below the circular grating 102.

[0055] Of course, the number of graduations 1022 is not limited here, and those skilled in the art can set it according to actual needs. One of the graduations is the zero-position graduation 1021. For example, in the initial state, the observation probe is opposite to the zero-position graduation 1021. Starting from the zero-position graduation 1021 and moving in a set direction, such as counterclockwise, each graduation or a set number of graduations indicates the angle of the graduation from the zero-position graduation 1021, or the sequential number starting from the zero-position graduation 1021.

[0056] In use, the circular grating 102 is mounted on the rotating component 200. The rotation center of the circular grating 102 coincides with the rotation center of the rotating component 200. The higher the degree of coincidence, the higher the measurement accuracy of the grating encoder. When the rotating component 200 rotates, it drives the circular grating 102 to rotate synchronously. At different times, the observation probe 101 reads the numbers on the scale. This number reflects the position of the circular grating 102 passing through the observation probe 101 at the set time. Based on the above measurement results, parameters such as the rotation angle and angular velocity of the rotating component 200 can be calculated.

[0057] After being installed on the rotating component 200, the position of the circular grating 102 needs to be corrected so that the center position of the circular grating 102 is as close as possible to the rotation center position of the rotating component 200.

[0058] The angular position of the circular grating 102 is the angle through which the circular grating 102 rotates at different times. For example, a curve showing the change of the angle of the circular grating 102 over time can be generated to visually display the angular position of the circular grating 102.

[0059] The angular position of the rotating component 200 under standard conditions is the actual angle rotated by the rotating component 200 at different times. For example, the angular position of the rotating component 200 under standard conditions is calibrated by a high-precision encoder, the measurement accuracy of which is greater than that of the circular grating 102. Due to its high measurement accuracy, the angle calibrated by the high-precision encoder at different times can be used as the angular position under standard conditions.

[0060] Alternatively, the angular position of the rotating component 200 under standard conditions can be the angular position of the rotating component 200 rotating at a constant speed. The curve for the angular position of uniform rotation is: θ = w * t. Where, θ: angle; w: angular velocity of uniform rotation; t: time. This curve can be used instead of the curve calibrated by the high-precision encoder.

[0061] The difference between the angular position of the circular grating 102 and the angular position of the rotating component 200 under standard conditions is actually the error of the circular grating 102. Within one rotation cycle of the circular grating 102, this error may be positive, negative, or zero. The maximum difference is positive or zero. The minimum difference is negative or zero.

[0062] To facilitate obtaining the maximum and minimum differences, a curve can be plotted showing how the error changes with different positions of the grating encoder. For example... Figure 5 and Figure 6 As shown, the ordinate at the peak of the curve represents the maximum difference, and the ordinate at the trough of the curve represents the minimum difference. The difference between the maximum and minimum differences is the difference between the peak and trough on the ordinate within the same period.

[0063] After the zero position of the circular grating 102 appears, the angle corresponding to the first maximum difference is the angle at which the error reaches its maximum value. What needs to be obtained is the difference between this angle and the angle corresponding to the zero position.

[0064] The order of steps S14 and S15 is not limited. The two steps can be performed simultaneously or separately, as long as the relative distance and relative orientation between the center of the circular grating 102 and the rotation center of the rotating member 200 can be obtained. The relative distance is the distance between the center of the circular grating 102 and the rotation center of the rotating member 200. The relative orientation is the angle between the center of the circular grating 102 and the rotation center of the rotating member 200.

[0065] Given the calculated relative distance and relative orientation, the relative position of the center of the circular grating 102 with respect to the rotation center of the rotating member 200 is adjusted so that the center of the circular grating 102 coincides with the center of the rotating member 200 as much as possible.

[0066] In this embodiment, the eccentric position calculation and correction method does not require measurement by external measuring elements. The relative position of the center of the circular grating 102 with respect to the rotation center of the rotating member 200 is calculated using the rotation information read from the grating encoder itself, thus providing a basis for position correction of the center of the circular grating 102, making position correction of the circular grating 102 easier.

[0067] Furthermore, since the error is periodically changing, the relative position can be calculated using the periodically changing values. Compared to measuring multiple data points using external measuring instruments, this method yields a more accurate relative position.

[0068] Furthermore, by using multiple periodic changes, the coincidence between the circular grating 102 and the rotation center of the rotating member 200 can be increased.

[0069] In one example, the difference between the maximum and minimum differences obtained from the acquisition of the differences, and the difference between the angle corresponding to the first maximum difference and the angle corresponding to the zero-position signal after the occurrence of the zero-position signal of the circular grating 102, are among the following:

[0070] It can be, such as Figure 5 or Figure 6 As shown, by generating a curve of the difference between the angular position of the circular grating 102 and the angular position of the rotating component 200 under standard conditions within at least one rotation cycle of the rotating component 200 relative to the position of the circular grating 102, the difference between the maximum difference and the minimum difference, as well as the difference between the angle corresponding to the first maximum difference and the angle corresponding to the zero position signal, are obtained.

[0071] Alternatively, by generating a curve of the difference between the angular position of the circular grating 102 and the angular position of the rotating component 200 under standard conditions within at least one rotation cycle of the rotating component 200 relative to the standard position, the difference between the maximum difference and the minimum difference, as well as the difference between the angle corresponding to the first maximum difference and the angle corresponding to the zero position signal, can be obtained.

[0072] It should be noted that, under normal circumstances, the angular position of the circular grating 102 at the same moment is very close to the standard position, and the error caused by the difference between the two positions can be ignored during calculation.

[0073] Therefore, regardless of which curve is used, the relative orientation and relative distance between the center of the circular grating 102 and the rotation center of the rotating member 200 can be obtained.

[0074] In one example, the rotating component 200 rotates at a constant speed. Compared to variable speed motion, the angular position measurement of the rotating component 200 and the circular grating 102 is more accurate during constant speed rotation, resulting in smaller errors in relative orientation and relative distance.

[0075] Of course, the rotating component 200 can also be a variable speed motion. As long as the relative orientation and relative distance can be obtained, it is acceptable.

[0076] In one example, the rotating component 200 rotates for at least two cycles. At least two cycles effectively reduce calculation errors caused by measurement errors. The operator can select a period of stable curve change to obtain the error values ​​of peaks and troughs, as well as the difference between the angle corresponding to the first maximum difference and the angle corresponding to the zero point after the circular grating 102 reaches zero.

[0077] In one example, as previously described, the encoder further includes an observation probe 101 configured to acquire the angle of the circular grating 102. Initially, the zero point of the circular grating 102 is opposite to the observation probe 101. In this way, the position of the zero point of the circular grating 102 on the curve is more easily obtained, thus simplifying subsequent calculations.

[0078] This disclosure also provides methods for calculating relative distance and relative orientation. (See reference...) Figure 3 The details are as follows:

[0079] Where O is the center of the circular grating 102, i.e., the center of the circle;

[0080] O' is the rotation center of rotating component 200;

[0081] R is the radius of the circular grating 102;

[0082] A is the difference between the maximum and minimum differences among the differences, that is, the difference between the peak and the trough.

[0083] R' is the distance from the point on the grating read by the optical probe at any given moment to the center of rotation.

[0084] During the rotation of the circular grating 102, r and R are fixed values, while R', ∠POO', and ∠OO'P all change with the rotation.

[0085] Let θ=∠POO', α=∠OO'P, β=∠OPO'

[0086] Using the law of cosines, we can derive:

[0087]

[0088] When the circular grating 102 is completely aligned with the rotation center, within a very small rotation angle dα, the distance the grating scale sweeps across the front of the probe is:

[0089] dS=R·dα;

[0090] When there is eccentricity, the distance the grating scale sweeps from in front of the probe is:

[0091] dS'=R'·dα.

[0092] It should be noted that the influence of the angle between OP and 0'P and the normal monitored by the optical probe is ignored here. This is because, when the installation error is very small, this influence is a second-order small quantity, and it is ignored to facilitate subsequent derivations. When smaller sources of error need to be considered, their influence must be taken into account, and numerical analytical methods should be used for analysis.

[0093] Therefore, within the rotation angle dα, the displacement error caused by eccentricity is:

[0094] d ε =dS'-dS=(R'-R)·dα

[0095] Therefore, starting from the initial position α0, the cumulative measurement error of the grating encoder until it rotates to α is:

[0096]

[0097] Substituting equation (1) into equation (2), we get:

[0098]

[0099] Since r << R, we can ignore second-order minor quantities. 2 -2R·r·cosθ is approximately equal to -2R·r·cosθ. It is approximately R. Therefore, simplifying (3) yields:

[0100]

[0101] Furthermore, using the law of sine, It can be seen that when r << R and R', β is approximately 0.

[0102] Therefore, θ = 180° - α, substituting it into (4) yields...

[0103]

[0104] It should be noted that ε above represents the error in the measured displacement, which needs to be further converted to the error in the measured rotation angle. The displacement of one revolution of the circular grating is 2πR, corresponding to an angle of 360°, which is 1,296,000 arcseconds.

[0105] Therefore, the arcsecond error corresponding to ε is:

[0106]

[0107] It should be noted that Figure 3 The curve in the figure represents the change of ε with respect to the increment Δα of α.

[0108] α=Δα+α0, therefore, by substituting the variables in (5), we can obtain:

[0109]

[0110] Therefore, the encoder error ε (arcseconds) is expressed as a function of the independent variable Δα ( Figure 3 The curve contains the following information:

[0111]

[0112] The first peak occurs at position B, satisfying B + α0 = 90°, thus α0 = 90 - B.

[0113] θ0≈180°-α0=90°+B

[0114] If a more accurate error curve is needed, the second-order small quantity that was ignored in the above derivation can be substituted in and obtained by numerical analysis. This will not be elaborated on here.

[0115] In addition, it can also be done through Figure 5 The mean of the curve is obtained by using formula (6), where the mean equals... Obtain the azimuth information.

[0116] In one example, the relative distance is obtained using the following formula:

[0117] r = 2π * A * R / 1296000

[0118] Where r: relative distance; A: the difference between the maximum and minimum differences; R: the radius of the circular grating 102.

[0119] In one example, the relative orientation is obtained using the following formula:

[0120] θ = 90 + B

[0121] Wherein, θ: relative orientation; B: the difference between the angle corresponding to the first maximum difference after the zero-position signal of the circular grating 102 appears and the angle corresponding to the zero-position signal.

[0122] Therefore, the relative distance can be obtained optionally using the following formula:

[0123] r = A * R / 412410 (mm)

[0124] Where r: relative distance; A: the difference between the maximum and minimum differences; R: the radius of the circular grating.

[0125] Alternatively, the relative orientation can be obtained using the following formula:

[0126] θ = 90 + B (degrees)

[0127] Wherein, θ: relative orientation; B: the difference between the angle corresponding to the first maximum difference after the zero-position signal of the circular grating appears and the angle corresponding to the zero-position signal.

[0128] In one example, during the adjustment of the relative position of the center of the circular grating 102 with respect to the center of the rotating member 200 based on the relative distance and the relative orientation,

[0129] In this example, the displacements that the circular grating 102 should be adjusted in the X and Y axes are obtained through trigonometric transformation. In this way, the circular grating 102 can be moved more precisely.

[0130] In one example, the corrective method also includes:

[0131] S16. Determine whether the coincidence between the center of the circular grating and the rotation center of the rotating component reaches a set value:

[0132] If the condition is not met, the step of obtaining the difference between the maximum and minimum differences is performed. For example, under this condition, the rotating member continues to rotate for the next cycle. The difference between the angular position of the circular grating 102 and the angular position of the rotating member 200 under standard conditions within at least one rotation cycle of the rotating member 200 is obtained again. And the following steps are performed until the overlap reaches a set value.

[0133] If the condition is yes, then the adjustment method ends.

[0134] Repeated corrections can achieve a higher degree of overlap, bringing the center of the circular grating closer to the rotation center of the rotating component.

[0135] <Example>

[0136] like Figure 2 , Figure 4 , Figure 6 As shown, the radius of the circular grating 102 is 60 mm. This circular grating 102 is mounted on the rotary table spindle assembly. The rotary table spindle assembly rotates at a constant speed of 5 rpm.

[0137] The method for calculating and correcting the eccentric position of the grating encoder includes:

[0138] S21. Obtain the difference between the angular position of the circular grating 102 and the angular position of the rotating component 200 under standard conditions within at least one rotation cycle of the rotating component 200.

[0139] In this step, the angle of the circular grating 102 is obtained as a function of time. The angular position curve under standard conditions is: θ = w * t. Where, θ: angle; w: uniform rotational angular velocity; t: time. The difference between this curve and the angular position under standard conditions is calculated. The curve showing the change in error with the angular position of the grating encoder is shown below. Figure 5 or Figure 6 As shown in the C-curve.

[0140] S22. Obtain the difference between the maximum and minimum differences among the differences, and the difference between the angle corresponding to the first maximum difference and the angle corresponding to the zero position after the zero position of the circular grating 102 appears.

[0141] In this step, such as Figure 5 As shown, the difference between the maximum and minimum differences is the difference in the ordinate of the peak and trough within the same period. In this example, the difference A is 137.5 arcseconds.

[0142] After the zero position of the circular grating 102 appears, the difference between the angle corresponding to the first maximum difference and the angle corresponding to the zero position is... Figure 5 The angle corresponding to the first peak after the middle zero position and Figure 5 The difference in angles corresponding to the zero position. In this example, the difference B is 52.4 degrees.

[0143] S23. Based on the difference between the maximum and minimum differences and the radius of the circular grating 102, the relative distance between the center of the circular grating 102 and the center of the rotating member 200 is obtained.

[0144] In this step, the difference A is substituted into the formula r = A * R / 412410 (mm).

[0145] The value of r is 0.02 mm.

[0146] S24. Based on the difference between the angle corresponding to the first maximum difference and the angle corresponding to the zero position signal, the relative orientation between the center of the circular grating 102 and the center of the rotating member 200 is obtained.

[0147] In this step, the difference B is substituted into the formula θ = 90 + B (degrees).

[0148] The value of θ is 142.4 degrees.

[0149] S25. Adjust the relative position of the center of the circular grating 102 with respect to the center of the rotating member 200 according to the relative distance and the relative orientation.

[0150] In this step, triangulation is used to determine the required displacements of the circular grating 102 in the X-axis and Y-axis directions, which are 0.0122 mm and 0.0159 mm, respectively. The position of the circular grating 102 is then adjusted based on these displacements.

[0151] After adjustment, the angular position of the circular grating 102 is remeasured within at least one rotation cycle of the rotating component 200, and the difference between this angular position and the angular position under standard conditions is calculated. A curve is generated showing the change of this difference with the angular position of the grating encoder. The resulting curve is shown below. Figure 6 As shown in the D curve.

[0152] Depend on Figure 6 As shown by the D curve, the measurement error of the grating encoder is significantly reduced after position correction compared to before correction. This indicates that the position correction method significantly improves the coincidence between the center of the grating encoder and the rotation center of the rotating component 200.

[0153] S26. Determine whether the coincidence degree between the center of the circular grating and the rotation center of the rotating component reaches a set value.

[0154] In this example, the overlap was determined to meet the requirements.

[0155] The above embodiments mainly describe the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. For the sake of brevity, they will not be elaborated here.

[0156] While specific embodiments of the invention have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of the invention. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.

Claims

1. A method for calculating and correcting the eccentric position of an encoder, characterized in that, include: The difference between the angular position of the circular grating and the angular position of the rotating component under standard conditions is obtained during at least one rotation cycle of the rotating component; Obtain the difference between the maximum and minimum differences among the differences, and the difference between the angle corresponding to the first maximum difference and the angle corresponding to the zero position after the zero position of the circular grating appears; The relative distance between the center of the circular grating and the rotation center of the rotating component is obtained based on the difference between the maximum and minimum differences and the radius of the circular grating. The relative orientation of the center of the circular grating and the center of the rotating component is obtained based on the difference between the angle corresponding to the first maximum difference and the angle corresponding to the zero position signal. The relative position of the center of the circular grating with respect to the rotation center of the rotating component is adjusted according to the relative distance and the relative orientation.

2. The eccentricity position calculation and correction method according to claim 1, characterized in that, Among the differences obtained, the difference between the maximum and minimum differences, and the difference between the angle corresponding to the first maximum difference and the angle corresponding to the zero-position signal after the occurrence of the zero-position signal of the circular grating, By generating a curve of the difference between the angular position of the circular grating and the angular position of the rotating component under standard conditions within at least one rotation cycle of the rotating component, relative to the position of the circular grating, the difference between the maximum difference and the minimum difference, as well as the difference between the angle corresponding to the first maximum difference and the angle corresponding to the zero position signal, are obtained. or By generating a curve of the difference between the angular position of the circular grating and the angular position of the rotating component under standard conditions within at least one rotation cycle of the rotating component, relative to the standard position, the difference between the maximum difference and the minimum difference, as well as the difference between the angle corresponding to the first maximum difference and the angle corresponding to the zero position signal, are obtained.

3. The eccentricity position calculation and correction method according to claim 1, characterized in that, The angular position of the rotating component under standard conditions is calibrated using a high-precision encoder. The measurement accuracy of the high-precision encoder is greater than that of the circular grating, or The angular position of the rotating component under standard conditions is the angular position of the rotating component rotating at a constant speed.

4. The eccentricity position calculation and correction method according to claim 1, characterized in that, The rotating component rotates at a constant speed or moves at a variable speed.

5. The eccentricity position calculation and correction method according to claim 1, characterized in that, The rotating component rotates for at least two cycles.

6. The eccentricity position calculation and correction method according to claim 1, characterized in that, The encoder also includes an observation probe configured to acquire the angle of the circular grating, wherein, in the initial state, the zero position of the circular grating is opposite to the observation probe.

7. The eccentricity position calculation and correction method according to any one of claims 1-6, characterized in that, The relative distance is obtained using the following formula: r=2π*A*R / 1296000 Where r: relative distance; A: the difference between the maximum and minimum differences; R: the radius of the circular grating.

8. The eccentricity position calculation and correction method according to any one of claims 1-6, characterized in that, The relative orientation is obtained using the following formula: θ = 90 + B Wherein, θ: relative orientation; B: the difference between the angle corresponding to the first maximum difference after the zero-position signal of the circular grating appears and the angle corresponding to the zero-position signal.

9. The eccentricity position calculation and correction method according to any one of claims 1-6, characterized in that, In adjusting the relative position of the center of the circular grating with respect to the rotation center of the rotating member based on the relative distance and the relative orientation, The displacements that the circular grating should be adjusted in the X and Y axes are obtained by triangulation.

10. The eccentricity position calculation and correction method according to claim 1, characterized in that, Also includes: Determine whether the coincidence degree between the center of the circular grating and the rotation center of the rotating component reaches a set value; If not, perform the step of obtaining the difference between the maximum and minimum differences among the differences.

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