JP7805852B2 - Calibration device, calibration method, and calibration program - Google Patents

Description

The present invention relates to a calibration device, a calibration method, and a calibration program.

Patent Document 1 describes a position detection device comprising: "a waveform correction unit that corrects the waveforms of a first signal detected from a first track provided on a moving body and having a scale with a predetermined period, and a second signal detected from a second track provided on the moving body and having a scale with a period shorter than the predetermined period; and a position calculation unit that calculates the position of the moving body based on the corrected first signal and the corrected second signal" (Claim 1). Furthermore, Patent Document 1 states that "the interpolation angle correction unit 700 corrects the pre-correction interpolation angle calculated by the interpolation angle calculation unit 250 and the interpolation angle calculation unit 260 based on error information of the interpolation angle obtained from the correction table 510. At this time, the interpolation angle correction unit 700 obtains the slit number corresponding to the absolute angle θref sent from the angle calculation unit 310, and corrects the interpolation angle corresponding to the slit number using the difference recorded in the correction table 510. The corrected interpolation angle is sent to the angle calculation unit 620. The angle calculation unit (second position calculation unit) 620 calculates the absolute angle based on the corrected interpolation angle. More specifically, the angle calculation unit 620 calculates the absolute angle based on the corrected interpolation angle and the slit number corresponding to the absolute angle θref sent from the angle calculation unit 310" (paragraph 0041).
[Prior art documents]
[Patent Documents]
[Patent Document 1] International Publication No. 2018/190019

The position detection device described in Patent Document 1 determines the slit number corresponding to the absolute angle θref, and corrects the interpolation angle corresponding to that slit number using the difference recorded in the correction table 510. Therefore, if the error in the absolute angle θref is large, the slit number may be incorrect, and an incorrect difference value may be read from the correction table.

A first aspect of the present invention provides a calibration device. The calibration device includes an acquisition unit that acquires the detected position of a moving body for each real position of the moving body; a calculation unit that calculates, for each detected position of the moving body, the error between a slit position signal that detects the slit position and an ideal slit number corresponding to the real position of the moving body; a determination unit that determines whether two or more real positions having at least some different slit numbers in units of a first slit of a predetermined size correspond to the same detected position; and a generation unit that, in response to two or more real positions corresponding to the same detected position, generates a correction value that corrects the magnitude of the error between the two or more real positions for the slit position signal at the detected position in accordance with the correspondence between the two or more real positions.

The generation unit may generate a correction value for the slit position signal in response to the fact that only one real position corresponds to a certain detected position, to correct for an error in the one real position at that detected position.

In any of the above calibration devices, the generation unit may generate a correction value for each section of the detection position acquired by the acquisition unit.

In any of the above calibration devices, the generation unit may calculate parameters of a correction function that represents a correction value corresponding to the detection position for each section of the detection position acquired by the acquisition unit.

In any of the above calibration devices, the generation unit may calculate the parameters of the correction function for each section of the detection position acquired by the acquisition unit by performing a Fourier series expansion on a set of correction values corresponding to the detection position.

In any of the above calibration devices, the generation unit may generate a correction value that corrects the slit position signal by an average magnitude of the errors at each of the two or more actual positions, in response to two or more actual positions corresponding to the same detection position.

In any of the above calibration devices, the generation unit may determine the correspondence between the actual position and the detected position by providing a margin at the boundary of the first slit. In any of the above calibration devices, the generation unit may generate a correction value using at least one actual position corresponding to the detected position, including a correspondence between the detected position and the actual position obtained by adding or subtracting a predetermined margin to or from the boundary of the first slit from the slit position signal.

Any of the above calibration devices may further include an output unit that outputs the correction value to an encoder that calculates the slit number in units of the first slit by rounding off the value obtained by adding the correction value to the slit position signal.

In any of the above calibration devices, the encoder may calculate the slit number by rounding the slit position signal plus the correction value to an integer.

In any of the above calibration devices, the output unit may write the correction value into a correction table provided by the encoder.

Any of the above calibration devices may further include an inspection unit that inspects whether an error occurs in the slit number calculated using the slit position signal corrected by the correction value generated by the generation unit.

In any of the above calibration devices, the moving body is a rotating body, and the rotating body has a first track including first slits for each first period obtained by dividing one revolution of the rotating body by a predetermined first number, and a second track including second slits for each second period obtained by dividing one revolution of the rotating body by a second number smaller than the first number, and the encoder to be calibrated may calculate the detected position of the moving body based on a first detection value detected from the first track and a second detection value detected from the second track.

The rotating body has a third track including third slits for each third period obtained by dividing one revolution of the rotating body by a third number different from the first number and the second number, and the encoder may further calculate the detected position of the moving body based on a third detection value detected from the third track.

A second aspect of the present invention provides a calibration method. The calibration method includes a calibration device acquiring the detected position of the moving body for each real position of the moving body, the calibration device calculating the error between a slit position signal that detects the slit position and an ideal slit number corresponding to the real position of the moving body for each detected position of the moving body, the calibration device determining whether two or more real positions having at least some different slit numbers in units of a first slit of a predetermined size correspond to the same detected position, and, if two or more real positions correspond to the same detected position, generating a correction value at the detected position that corrects the magnitude of the error between the slit position signal and the two or more real positions in accordance with the correspondence between the two or more real positions.

A third aspect of the present invention provides a calibration program executed by a computer. The calibration program causes the computer to function as an acquisition unit that acquires the detected position of a moving body for each real position of the moving body; a calculation unit that calculates, for each detected position of the moving body, the error between a slit position signal that detects the slit position and an ideal slit number corresponding to the real position of the moving body; a determination unit that determines whether two or more real positions having at least some different slit numbers in units of a predetermined size first slit correspond to the same detected position; and a generation unit that, in response to two or more real positions corresponding to the same detected position, generates a correction value that corrects the magnitude of the error between the two or more real positions for the slit position signal at the detected position in accordance with the correspondence between the two or more real positions.

Note that the above summary of the invention does not list all of the features of the present invention. Subcombinations of these features may also constitute inventions.

1 shows the configuration of a position detection device 10 according to the present embodiment. An example of the relationship between the ideal mechanical angle and the electrical interpolation angle is shown below. An example of the relationship between the ideal mechanical angle and the slit number is shown below. 10 shows an example of a slit position signal error for each ideal mechanical angle. An example of the slit position signal error for each ideal mechanical angle is shown focusing on slit number 20. An example of a slit position signal error for each measured mechanical angle is shown, focusing on the error value that should correspond to slit number 20 after correction. 7 shows the configuration of a calibration device 700 according to this embodiment. 7 shows an operation flow of the calibration device 700 according to this embodiment. 7 shows an example of correction values generated by the calibration device 700. 10 shows an example of a slit position signal error after correction. An example in which gaps occur in the correction values is shown below. An example of a method for interpolating gaps in correction values according to this embodiment will be described below. 13 shows the configuration of a position detection device 1300 according to a modified example of this embodiment. 10 shows an example of ideal values of the first slit position signal S _MSB according to a modified example of this embodiment. 10 shows an example of an ideal value of the second slit position signal S _LSB according to a modified example of the present embodiment. 10 shows an example of ideal values of the slit number according to a modified example of the present embodiment. 22 illustrates an example computer 2200 in which aspects of the present invention may be embodied, in whole or in part.

The present invention will be described below through embodiments of the invention, but the following embodiments do not limit the scope of the invention as claimed. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

Figure 1 shows the configuration of a position detection device 10 according to this embodiment. The position detection device 10 includes a moving body 100 and an encoder 110. The moving body 100 is a measured object whose position is to be detected by the encoder 110. In this embodiment, the moving body 100 is, as an example, a disk-shaped rotating body arranged perpendicular to its rotation axis. Alternatively, the moving body 100 may be a moving body that moves along a straight line relative to the encoder 110.

The moving body 100 has multiple tracks 105a-b (also referred to as "tracks 105"). Each track 105 includes multiple slits provided at predetermined intervals along the direction of movement of the moving body 100. In this embodiment, each track 105 includes multiple slits provided at equal intervals in the circumferential direction of the moving body 100, which is a rotating body, around the rotation axis. Each slit is a structure that can be detected by the encoder 110 using magnetism, light, electricity, or the like. For example, each slit is an opening or protrusion provided at equal intervals in the circumferential direction of the moving body 100, individual teeth of a gear formed on the outer periphery of the moving body 100, or a magnetized body magnetized at equal intervals in the circumferential direction of the moving body 100.

The multiple tracks 105 may be provided on the surface of the movable body 100 at positions with different distances (i.e., radii) from the rotation axis as the center. In this embodiment, track 105a is provided in the circumferential direction near the outer periphery of the movable body 100, and track 105b is provided in the circumferential direction adjacent to track 105a on the inner periphery of track 105a.

Here, the multiple tracks 105 have slits at different periods. In this embodiment, track 105a is an example of a first track and includes first slits at each first period obtained by dividing one circumference of movable body 100 by a predetermined first number N _-M . Track 105b is an example of a second track and includes second slits at each second period obtained by dividing one circumference of movable body 100 by a second number N _-N, which is smaller than the first number. Here, if movable body 100 has two tracks 105, the number of slits per circumference of track 105a (first number N _-M ) and the number of slits per circumference of track 105b (second number N _-N ) may be coprime. The first number N _-M and the second number N _-N may be determined so that the difference between them is 1. For example, the pair of first number N 1 _M and second number N 1 _N may be (8,7), (40,39), or (128,127), etc.

The encoder 110 calculates the detected position of the moving body 100 based on multiple detection values detected from multiple tracks 105 of the moving body 100. The encoder 110 includes multiple detection units 120a-b (also referred to as "detection units 120"), a slit position signal calculation unit 130, a slit number calculation unit 140, a correction table 150, a slit number correction unit 160, and a position calculation unit 170.

Each of the multiple detectors 120 is provided corresponding to a corresponding one of the multiple tracks 105 and outputs a detection value detected from the corresponding track 105. In this embodiment, the detector 120a functions as a first detector and detects and outputs a first detection value from the track 105a, which is an example of a first track. The detector 120b functions as a second detector and detects and outputs a second detection value from the track 105b, which is an example of a second track. Here, the detectors 120a and 120b output (electrical) insertion angles _θM and _θN , respectively, where the distance between adjacent slits in the corresponding tracks 105 is one period (=360 degrees).

The slit position signal calculation unit 130 is connected to multiple detection units 120. The slit position signal calculation unit 130 outputs a slit position signal SS using multiple detection values from the multiple detection units 120. The slit position signal indicates the slit number of the first slit detected by the detection units 120a-b as a value indicating the position of the moving body 100 detected by the encoder 110.

The slit number calculation unit 140 is connected to the slit position signal calculation unit 130. The slit number calculation unit 140 calculates a slit number S _M (i.e., the slit number of the slit where the moving body 100 is located) in units of first slits of a predetermined size, using the slit position signal SS output by the slit position signal calculation unit 130. Here, the detected position of the moving body 100 before the slit number correction unit 160 corrects the slit number is expressed as a pair of the slit number S _M and the interpolation angle θ _M. In this embodiment, the mechanical angle θ _d , which is an example of the detected position, is expressed by the following equation (1).

The correction table 150 is connected to the detection unit 120a and the slit number calculation unit 140. The correction table 150 stores, for each slit number, a set of correction values corresponding to the first detection signal (interpolation angle θ _M ) detected from the first track. The correction table 150 outputs the correction value S _cal associated with the interpolation angle θ _M specified by the first detection signal from the set of correction values associated with the slit number S _M received from the slit number calculation unit 140.

The slit number correction unit 160 is connected to the slit position signal calculation unit 130 and the correction table 150. The slit number correction unit 160 corrects the slit position signal SS received from the slit position signal calculation unit 130 using the correction value S _cal received from the correction table 150. The slit number correction unit 160 then calculates a corrected slit number _S'M based on the corrected slit position signal. Here, the slit number correction unit 160 calculates a slit number in units of the first slit by rounding off the value obtained by adding the correction value to the slit position signal SS from the slit position signal calculation unit 130. When the decimal point of the slit position signal SS is located at a position where the integer part of the slit position signal SS corresponds to the slit number, the slit number correction unit 160 calculates a slit number by rounding off the value obtained by adding the correction value to the slit position signal SS to an integer.

The position calculation unit 170 is connected to the detection unit 120a and the slit number correction unit 160. The position calculation unit 170 calculates the position (corrected position) of the moving body 100 using the slit number _S'M received from the slit number correction unit 160 and the first detection signal received from the detection unit 120a. In this embodiment, the position calculation unit 170 outputs a mechanical angle θ, with one rotation of the moving body 100 being one period, as a value indicating the position of the moving body 100.

Figure 2 shows an example of the relationship between the ideal mechanical angle and the electrical interpolation angle. Here, "ideal mechanical angle" refers to the mechanical angle when error is not taken into account, and corresponds to the actual position (real position) of the moving body 100. Each of the multiple detection units 120 outputs an electrical interpolation angle, with the distance between adjacent slits in the corresponding track 105 being one period. As an example, each detection unit 120 has two sensors that detect the slits in the track 105, and a phase difference of 1/4 period (90 degrees) between the slits is provided between the two sensors. This allows the two sensors to detect sine and cosine voltages corresponding to the electrical interpolation angle from the slit being sensed.

Each detection unit 120 may correct the waveforms of the sine voltage and cosine voltage output from the two sensors. Specifically, each detection unit 120 may correct at least one of the offset, gain, phase, or distortion of the sine voltage and cosine voltage.

Next, each detection unit 120 calculates the arctangent (arctan ⁻¹ ) using the sine voltage and the cosine voltage to calculate the interpolation angle. Each detection unit 120 may correct the interpolation angle using distortion in the amplitude of the sine voltage and the cosine voltage, or the like.

In the example shown in the figure, track 105a has eight slits per revolution of movable body 100, and track 105b has seven slits per revolution of movable body 100. When movable body 100 rotates once (from 0 degrees to 360 degrees), the interpolation angle θ _M output by detection unit 120a repeats eight periods from 0 degrees to 360 degrees, and the interpolation angle θ _N output by detection unit 120b repeats seven periods from 0 degrees to 360 degrees. Therefore, the difference between these interpolation angles θ _M - θ _N changes from 0 degrees to 360 degrees as movable body 100 makes one revolution, as shown in FIG. 2 , and corresponds to the mechanical angle θ _d shown in equation (1).

The slit position signal calculation unit 130 calculates a slit position signal SS indicating a slit number corresponding to the detection position using the interpolation angles θ _M and θ _N. Ideally, the slit position signal SS should match the slit number S _M output by the slit number calculation unit 140. Therefore, by replacing the slit number S _M in equation (1) with the slit position signal SS and substituting the difference in interpolation angles θ _M - θ _N for the mechanical angle θd in equation (1) and rearranging it, the slit position signal SS is expressed by the following equation (2). Note that equation (2) shows the case where N _N = N _M - 1.
As shown in equation (2), the slit position signal calculation unit 130 cancels out the change in the slit position signal _SS that accompanies the change in the interpolation angle θ _M within one slit period of the track 105 a by multiplying the difference in interpolation angles θ _M - _{θ N} by N _M and subtracting the interpolation angle θ M. By dividing this by the angle of one period (360 degrees), the slit position signal calculation unit 130 can calculate the slit position signal SS that ideally takes an integer value from 0 to N _M -1 according to the slit number on the track 105 a when the moving body 100 makes one revolution.

In another embodiment, the slit position signal calculation unit 130 may adjust the slit position signal SS using a pre-correction function that calculates a correction value for correcting the slit position signal SS before outputting it. Such a pre-correction function may be based on, for example, the interpolation angles θ _M and θ _N output by the detection units 120 a and 120 b, or on the amplitudes R _M and R _N of the detection values of the detection units 120 a and 120 b. The pre-correction function may be, for example, a sine wave (sin) of the difference θ _M - θ _N between the interpolation angles output by the detection units 120 a and 120 b, with its magnitude and phase adjusted according to the target correction amount.

Figure 3 shows an example of the relationship between the ideal mechanical angle and the slit number. The graph in this figure shows the value of the slit position signal SS according to the mechanical angle when there is no error. When there is no error, the slit position signal SS output by the slit position signal calculation unit 130 indicates the slit number according to the mechanical angle of the moving body 100, such as 0 when the moving body 100 is located at a mechanical angle corresponding to the first cycle of the track 105a, 1 when the moving body 100 is located at a mechanical angle corresponding to the second cycle of the track 105a, and so on.

The slit number calculation unit 140 may calculate the slit number S _M according to the detected position (mechanical angle) of the moving body 100 by rounding off the slit position signal as shown in the following equation (3). In this case, the slit position signal SS has a margin for error in the range of -0.5 or more and less than +0.5. Therefore, the slit number calculation unit 140 can calculate the correct slit number S _M even if the slit position signal has an error in the range of -0.5 or more and less than +0.5.

4 shows an example of the slit position signal error for each ideal mechanical angle. This figure illustrates an example in which the moving body 100 has tracks 105a and 105b with a first number N _M = 40 and a second number N _N = 39. In this case, one slit period of the track 105a corresponds to a mechanical angle of 9 degrees (360÷40=9).

The slit position signal error in this figure is a value (error) obtained by subtracting the ideal value S ideal of the slit position signal SS at the ideal mechanical angle from the slit position signal SS actually output by the slit position signal calculation unit 130 when the position of the movable body 100 is at that ideal mechanical angle. For example, to calibrate the position detection device 10, such a slit position signal error can be measured by measuring the ideal mechanical angle including _{the ideal} slit number S _ideal with an ideal encoder (e.g., an encoder used as a calibration reference for the encoder 110) while rotating the movable body 100, and acquiring the slit position signal SS output by the slit position signal calculation unit 130. In the example shown in this figure, the slit position signal error exceeds the range of ±0.5 depending on the ideal mechanical angle.

Figure 5 shows an example of a slit position signal error for each ideal mechanical angle, focusing on slit number 20. The slit position signal error in this figure is the same as in Figure 4. Slit number 20 corresponds to a mechanical angle of 180 to 189 degrees. Error 500a (slit position signal error 500a) indicates that the slit number indicated by the slit position signal SS is 2 less than slit number 20, which corresponds to the ideal mechanical angle. In other words, this indicates that the value of the slit position signal SS is within the range corresponding to slit number 18 (for example, greater than or equal to 17.5 and less than 18.5).

Similarly, error 500b indicates that the slit number indicated by the slit position signal SS is within a range corresponding to slit number 19, which is one less than slit number 20 corresponding to the ideal mechanical angle; error 500c indicates that the slit number indicated by the slit position signal SS is the same as slit number 20 corresponding to the ideal mechanical angle; error 500d indicates that the slit number indicated by the slit position signal SS is within a range corresponding to slit number 21, which is one more than slit number 20 corresponding to the ideal mechanical angle; and error 500e indicates that the slit number indicated by the slit position signal SS is within a range corresponding to slit number 22, which is two more than slit number 20 corresponding to the ideal mechanical angle. Thus, when the slit position signal error exceeds the range of ±0.5, the slit number indicated by the slit position signal SS differs from the ideal slit number.

6 shows an example of the slit position signal error for each measured value of the mechanical angle, focusing on the error value that should correspond to slit number 20 after correction. While FIGS. 4 and 5 show the slit position signal error acquired for each actual position of the mobile body 100 during calibration of the position detection device 10, this figure shows what correction value S _cal should be used by the position detection device 10 after calibration for the slit position signal SS indicating the slit number for each detected position of the mobile body 100. Specifically, it shows what correction value S _cal should be used by the slit number correction unit 160 to correct the slit position signal SS when the position detection device 10 is actually used.

The horizontal axis of this diagram represents a value corresponding to the pre-correction mechanical angle (i.e., detected position) obtained by adding the interpolation angle θ _M from the detection unit 120 to the pre-correction slit number S _M from the slit number calculation unit 140. Here, the interpolation angle θ _M from the detection unit 120 is normalized to the range of 0 to 9 degrees by multiplying it by 1/N _M.

The slit number correction unit 160 calculates the corrected slit number S' _M (i.e., the ideal value S ideal of the slit position signal) by adding the correction value S _cal to the slit position signal SS from the slit position signal calculation unit 130 and rounding off the result. Therefore, the slit position signal error is the slit position signal SS - the _{ideal value S ideal ,} whereas the correction value S _cal is the ideal value S _ideal - the slit position signal SS. Therefore, the correction value S _cal is a value obtained by reversing the sign of the slit position signal error.

Error 500a in Figure 5 corresponds to slit number 18 according to the slit position signal SS. Therefore, when converted so that the measured mechanical angle is the horizontal axis, error 500a in Figure 5 is shifted to slit number 18, becoming error 600a, which overlaps with error 610 that originally existed at slit number 18. Similarly, error 500b in Figure 5 is shifted to slit number 19, becoming error 600b, which overlaps with the slit position signal error that originally existed at slit number 19; error 500d in Figure 5 is shifted to slit number 21, becoming error 600d, which overlaps with the slit position signal error that originally existed at slit number 21; and error 500e in Figure 5 is shifted to slit number 22, becoming error 600e, which overlaps with the slit position signal error that originally existed at slit number 22.

In this way, when the slit position signal SS is measured for each real position (ideal mechanical angle) of the movable body 100 and the slit position signal error for each real position is calculated, the slit position signal error is determined to be one point for each real position ( FIG. 5 ). However, if the slit position signal error exceeds the range of ±0.5 and the slit number indicated by the slit position signal SS differs from the slit number corresponding to the real position of the movable body 100, when the slit position signal error is converted into a slit position signal error for each detected position of the movable body 100 (slit number S _M + interpolation angle θ _M /N _M ), two or more actual positions may correspond to the same detected position, and as a result, two or more slit position signal errors may correspond.

Therefore, for a position detection device 10 in which the slit position signal error is large and the measured slit number differs from the ideal slit number, two or more correction values (values with the slit position signal error reversed) will appear for the same detection position. In such cases, the question arises as to what correction value the calibration device of the position detection device 10 should calibrate so that the correction table 150 in the encoder 110 outputs.

Figure 7 shows the configuration of a calibration device 700 according to this embodiment. The calibration device 700 may be a computer such as a PC (personal computer), workstation, server computer, or general-purpose computer, or may be a computer system in which multiple computers are connected. Such computer systems are also considered to be computers in a broad sense. The calibration device 700 may also be implemented using one or more virtual computer environments executable within the computer. Alternatively, the calibration device 700 may be a dedicated computer designed for calibrating the encoder 110, or may be dedicated hardware realized using dedicated circuitry. When the calibration device 700 is implemented by a computer, the calibration device 700 may function as each of the components shown in this figure by executing a calibration program.

The calibration device 700 is connected to the encoder 110 to calibrate the encoder 110, for example, after manufacturing the position detection device 10 and before shipping it, or during inspection or diagnosis of the position detection device 10. During this calibration, if two or more correction values appear for the same detected position of the moving body 100, the calibration device 700 sets an appropriate correction value in the encoder 110. The calibration device 700 includes an acquisition unit 710, a calculation unit 714, a determination unit 716, a generation unit 720, an inspection unit 730, and an output unit 740.

The acquisition unit 710 acquires the detected position of the mobile body 100 for each actual position of the mobile body 100. Here, the acquisition unit 710 acquires, as the actual position of the mobile body 100, S _ideal , which is an ideal value of the slit position signal SS and indicates the slit number of the actual position, and θ _mideal , which indicates the interpolation angle of the actual position, from a reference encoder attached to the mobile body 100 for calibration work and used as a calibration reference. The acquisition unit 710 also acquires, as the detected position of the mobile body 100, a slit position signal SS that detects the slit position of the detection position and is output by the slit position signal calculation unit 130, and an interpolation angle θ _M , which is detected by the detection unit 120a for the detection position, from the encoder 110.

Note that, instead of acquiring the slit position signal SS from the encoder 110, the acquiring unit 710 may acquire the interpolation angles θ _M and θ _N output by the detecting units 120 a-b in the encoder 110 as the detected position of the moving body 100. Furthermore, the acquiring unit 710 may acquire a sinn value indicating a sine voltage and a cos value indicating a cosine voltage detected by each of the detecting units 120 a-b as the detected position of the moving body 100. In this case, the acquiring unit 710 may calculate the slit position signal SS in the same manner as the detecting units 120 a-b and the slit position signal calculating unit 130.

The calculation unit 714 is connected to the acquisition unit 710. The calculation unit 714 uses the slit position signal SS to calculate an error between the slit position signal SS and an ideal slit number S _ideal corresponding to the actual position for each detected position of the moving body 100. The determination unit 716 is connected to the calculation unit 714. The determination unit 716 determines whether two or more actual positions having at least some different slit numbers in units of the first slit correspond to the same detected position. The generation unit 720 is connected to the determination unit 716. The generation unit 720 uses the calculated error to generate a correction value S _cal of the slit position signal SS for each detected position of the moving body 100. Here, in response to the fact that two or more actual positions having at least some different slit numbers in units of the first slit correspond to the same detected position, the generation unit 720 generates a correction value S _cal that corrects the magnitude of the difference between the errors at the two or more actual positions for the slit position signal SS at that detected position.

The inspection unit 730 is connected to the generation unit 720. The inspection unit 730 inspects whether an error occurs in the slit number calculated using the slit position signal corrected by the correction value S _cal generated by the generation unit 720. The inspection unit 730 may determine that no error occurs in the slit number when the difference between the slit position signal corrected by the correction value S _cal generated by the generation unit 720 and the slit number S _ideal corresponding to the actual position is within a predetermined reference range. This reference range may be, for example, a range of ±50% of the width of one slit number, or may be a smaller range. The inspection unit 730 issues an alert when it determines that an error occurs in the slit number. Note that the calibration device 700 does not have the inspection unit 730 and does not need to have a function for inspecting the correction value S _cal .

The output unit 740 outputs the correction value S _cal for each inspection position generated by the generation unit 720. The output unit 740 may output the correction value S _cal for each inspection position to the encoder 110. For example, the output unit 740 may write the correction value S _cal for each inspection position to the correction table 150 included in the encoder 110. Furthermore, for example, the output unit 740 may store the correction value S _cal for each inspection position in a storage device such as a memory or a hard disk drive.

Figure 8 shows the operational flow of the calibration device 700 according to this embodiment. In step 800 (S800), the acquisition unit 710 acquires the detected position of the mobile body 100 for each real position of the mobile body 100. The generation unit 720 converts the data format of the data in which the detected position is associated with each real position of the mobile body 100, and obtains data in which one or more real positions are associated with each detected position of the mobile body 100.

The generation unit 720 repeats the processes from S810 to S860 for each detection position of the moving body 100. In S820, the determination unit 716 determines whether two or more real positions, at least some of which have different slit numbers in units of the first slit, correspond to the same detection position. Furthermore, in S820, the calculation unit 714 may use the slit position signal SS to calculate an error between the ideal slit number S _ideal corresponding to the real position and the slit position signal SS for the target detection position. If only one real position corresponds to the target detection position ("N" in S830), the generation unit 720 generates a correction value S _cal for correcting the error at the one real position for the slit position signal SS at the target detection position in S840. As a result, for a detection position where the slit position signal error is within a range of ±0.5 and where slit position signal errors for other slit numbers at the ideal mechanical angle do not overlap, the generation unit 720 can generate a correction value S _cal (e.g., a correction value with the positive and negative signs of the slit position signal error) that cancels out one slit position signal error. Note that, in generating the correction value S _cal , the generation unit 720 may generate a correction value S _cal that completely cancels the error at one actual position, or may generate a correction value S _cal that reduces the error at one actual position. For example, when the correction value for each detection position of the slit position signal SS is approximated by a correction function as described below, the correction amount for each detection position approximates but does not necessarily match the error amount at one actual position for that detection position.

When two or more real positions having at least some different slit numbers correspond to the target detection position ("Y" in S830), the generation unit 720 generates a correction value S _cal that corrects the magnitude of the difference between the errors at the two or more real positions for the slit position signal SS at that detection position. As a result, when there are two or more errors (e.g., slit position signal errors) for the same detection position, the generation unit 720 can unify these errors and generate an appropriate correction value S _cal .

In S870, when the correction value S _cal for each detection position is generated, the inspection unit 730 inspects whether an error occurs in the slit number calculated using the slit position signal corrected with the correction value S _cal generated by the generation unit 720. Here, the inspection unit 730 inspects, for each detection position, whether the difference between the ideal slit number S _ideal and the slit number at one or more actual positions corresponding to the detection position when the slit position signal SS at that detection position is corrected with the correction value S _cal corresponding to that detection position is within a reference range. The inspection unit 730 outputs an alert when the difference between the slit number at at least one actual position and the slit number indicated by the corrected slit position signal at any detection position is outside the reference range.

In S880, the output unit 740 outputs the correction value S _cal for each inspection position generated by the generation unit 720. Here, if an alert is output in S870, the output unit 740 may interrupt the calibration process without outputting the correction value S _cal .

FIG. 9 shows an example of the correction value S _cal generated by the calibration device 700. In FIG. 9, the horizontal axis represents the measured mechanical angle (detected position), and the vertical axis represents the correction value S _cal (slit correction value) generated by the generation unit 720. FIG. 9 shows the correction value S _cal corresponding to the slit position signal error shown in FIGS. 4 to 6. Note that when the slit number correction unit 160 in the encoder 110 adds the correction value S _cal to the slit position signal SS, the correction value S _cal becomes a value obtained by inverting the sign of the slit position signal error. However, in this figure, for ease of comparison with FIGS. 4 to 6, the correction value S _cal is shown without inverting the sign of the slit position signal error.

Focusing on the interval where the measured mechanical angle (detected position) is from 155.25 degrees to 157.50 degrees, two real positions with different slit numbers correspond to each detected position in this interval. Therefore, at each detected position in this interval, there is an error (slit position signal error) corresponding to each of the two real positions. In this case, the generation unit 720 generates a correction value S _cal that corrects the error between the errors corresponding to each of the two real positions. Here, the "magnitude between two errors" refers to the magnitude between the two errors excluding both ends, meaning that the magnitude is the middle between these two errors, rather than adopting only one of the two errors.

For example, in response to two or more real positions corresponding to the same detection position, the generation unit 720 generates a correction value S _cal that corrects the slit position signal SS by an average magnitude of errors at the two or more real positions. Furthermore, the generation unit 720 may adjust the correction value S _cal that corrects the magnitude between the errors at the two or more real positions so that the errors between the corrected slit position _signal and the slit numbers of the two or more real positions fall within a reference range.

Note that even when the measured mechanical angle (detection position) is in a range outside of 153 degrees to 162 degrees, there are locations where two actual positions with different slit numbers correspond to one detection position. For ease of explanation, Figure 9 omits the illustration of the range outside of 153 degrees to 162 degrees.

Fig. 10 shows an example of the slit position signal error after correction. In Fig. 10, the horizontal axis represents the measured mechanical angle (detected position), and the vertical axis represents the slit position signal error (error) between the slit position signal SS and each of the slit numbers S _ideal for one or more actual positions corresponding to each detected position. Here, the dashed line represents the slit position signal error before correction, and the solid line represents the slit position signal error after correction with a magnitude equal to the average of the errors at each of the two or more actual positions.

As shown by the solid line in this figure, the calibration device 700 generates a correction value S _cal that corrects the magnitude of the difference between errors at two or more actual positions at each detection position, and can output a correction value S _cal that can correct the slit position signal errors shown in Figures 4 to 6 so that the error for the slit number at each actual position is within a range of ±0.5.

The generating unit 720 described above generates the correction value S _cal for each detection position. Alternatively, the generating unit 720 may generate a correction value for each section of the detection positions acquired by the acquiring unit 710. For example, the generating unit 720 may generate a correction value S _cal for each section into which one period of the first slit is divided (for example, for each 15° of the interpolation angle). In this case, the generating unit 720 may calculate the correction value S _cal for the section by, for example, averaging the correction values calculated for each detection position within the section.

Furthermore, the generating unit 720 may calculate parameters of a correction function that expresses the correction value S _cal for each section of the detection position acquired by the acquiring unit 710. For example, the generating unit 720 may approximate the correction value S _cal for the range of interpolation angles 0° to 360° in each slit period of the first slit by a predetermined correction function such as Fourier series expansion. When using Fourier series expansion, the generating unit 720 may calculate correction coefficients (parameters) A _k and δ _k of the correction function that approximates the correction value S _cal at the interpolation angle θ _M by correction value = Σ _k A _k × sin(kθ M + δ _k ).

The generation unit 720 may calculate the correction coefficient by, for example, calculating correction values S _cal corresponding to interpolation angles at predetermined intervals as representative points and performing Fourier series expansion on a set of representative points. The output unit 740 writes the correction coefficients calculated by the generation unit 720 into the correction table 150. When the slit number correction unit 160 receives the slit number S _M from the slit number calculation unit 140 during actual use, it may read out the correction coefficient stored in the correction table 150 in association with the slit number S _M and calculate the correction value S _cal using a correction function that uses the correction coefficient.

Figure 11 shows an example in which a gap occurs in the correction value. As shown in Figures 5 and 6, if the slit position signal error for each actual position is converted into the slit position signal error for each detection position, for example, error 500a where the actual position is slit number 20 will be converted into error 600a where the detection position is slit number 18. As a result, depending on the detection position, it is possible for two or more slit position signal errors to exist, corresponding to two or more actual positions.

Conversely, depending on the detection position, the slit position signal error may be assigned to a different slit number, and as a result, no corresponding actual position may exist. In the example of Figure 11, when there are eight periods of the first slit per revolution of the moving body 100 (N _M = 8), a slit position signal error of 0.5 or more is shifted by +45° in mechanical angle (detection position), and a slit position signal error of less than -0.5 is shifted by -45° in mechanical angle, resulting in no actual position corresponding to the detection position in the area surrounded by the dashed line.

Here, detected positions for which no corresponding real position exists are positions that were not observed even when the real position of the mobile body 100 was changed within the entire movable range during the calibration process, and therefore will not occur in actual use unless an error or the like different from that during the calibration process occurs. However, the position detection device 10 may detect such detected positions due to temporary errors or fluctuations, etc.

FIG. 12 shows an example of a method for interpolating gaps in correction values according to this embodiment. When interpolating gaps in correction values, the determination unit 716 may determine the correspondence between the actual position and the detected position by providing a margin at the boundary of the first slit. Here, the generation unit 720 may generate a correction value at a certain detected position using at least one actual position corresponding to the detected position, including a correspondence between the detected position and the actual position obtained by adding or subtracting a predetermined margin to or from the boundary of the first slit for the slit position signal. In this embodiment, the generation unit 720 adds a slit number S _M determined from the slit position signal SS (i.e., S _M =round(SS)) to a slit number determined by adding or subtracting a predetermined margin ε to or from the slit position signal SS (i.e., S _M =round(SS±ε)), and generates a correction value including these. Here, the margin ε is a value smaller than the margin (0.5) used to determine the slit number.

When the margin ε is subtracted from the slit position signal SS, if the slit position signal error is positive, the slit position signal error will not move to another slit number until the slit position signal error becomes +ε greater than the slit number boundary (e.g., +0.5). In contrast, if the slit position signal error is negative, the point at which the slit position signal error becomes ε greater than the slit number boundary (e.g., -0.5) becomes the boundary at which the slit position signal error moves to another slit number.

Furthermore, when a margin ε is added to the slit position signal SS, if the slit position signal error is positive, the slit position signal error moves to another slit number at the point where the slit position signal error is ε smaller than the slit number boundary (e.g., +0.5). In contrast, if the slit position signal error is negative, the slit position signal error does not move to another slit number until the slit position signal error becomes even smaller by ε than the slit number boundary (e.g., -0.5).

In this way, by adding or subtracting the margin ε to the slit position signal SS and adding a signal that identifies the slit number, it is possible to assign a slit position signal error to a detection position that does not have a corresponding actual position, as shown in the example in Figure 12. The generation unit 720 can then fill in the gaps in the correction values for each detection position by generating correction values that include these slit position signal errors.

Furthermore, even if the detection position detected during actual use of the calibration device 700 varies from the detection position detected during calibration, resulting in fluctuations in the slit position signal, the calibration device 700 can prepare a correction value generated using a slit position signal error that simulates such fluctuations in advance by adding or subtracting a margin ε to the slit position signal. This enables the position detection device 10 to use robust correction values even when the output of the sensors in each detection unit 120 fluctuates due to, for example, changes in environmental temperature during actual use.

FIG. 13 shows the configuration of a position detection device 1300 according to a modified example of this embodiment. Because the position detection device 1300 is a modified example of the position detection device 10, a description thereof will be omitted hereinafter, except for the differences. The position detection device 1300 includes a moving body 1301 and an encoder 1310. The moving body 1301 is a measurement object whose position is detected by the encoder 1310. Similar to the moving body 100, the moving body 1301 has a first track having a first number N = _M of slits per revolution of the moving body 1301, and a second track having a second number N = _N of slits per revolution of the moving body 1301. Furthermore, the moving body 1301 according to this modified example further includes a third track including third slits at a third period obtained by dividing one revolution of the moving body 1301 by a third number N = _S , which is different from the first and second numbers.

Encoder 1310 calculates the detected position of moving body 1301 based on three detection values detected from the three tracks of moving body 1301. Encoder 1310 includes multiple detection units 1320a-c (also referred to as "detection units 1320"), multiple slit position signal calculation units 1330a-b (also referred to as "slit position signal calculation units 1330"), a slit number calculation unit 1340, a correction table 1350, a slit number correction unit 1360, and a position calculation unit 1370.

The detectors 1320a-c are provided corresponding to the first to third tracks, respectively, and output detection values detected from the corresponding tracks. In this embodiment, the detector 1320a functions as a first detector, detecting and outputting a first detection value from the first track. The detector 1320b functions as a second detector, detecting and outputting a second detection value from the second track. The detector 1320c functions as a third detector, detecting and outputting a third detection value from the third track. Here, the detectors 1320a-c output as detection values (electrical) interpolation angles θ _M , θ _N , and θ _S , where the distance between adjacent slits in the corresponding tracks is one period (=360 degrees). Each detector 1320 is similar to the detector 120 in other respects.

Each of the slit position signal calculation units 1330a-b is connected to a plurality of detection units 1320. The slit position signal calculation unit 1330a outputs a first slit position signal S _MSB using a plurality of detection values from the plurality of detection units 1320. In this embodiment, the first slit position signal S _MSB relates to the most significant bits of the slit number of the first track. The slit position signal calculation unit 1330b outputs a second slit position signal S _LSB using a plurality of detection values from the plurality of detection units 1320. In this embodiment, the second slit position signal S _LSB relates to the least significant bits of the slit number of the first track.

For any combination of the first number N _M , the second number N _N , and the third number N _S that can ultimately calculate the slit number S _M of the first track, the first slit position signal S _MSB and the second slit position signal S _LSB can be generalized to the following equations (4) and (5).

Here, _pM , _pN , _pS , _qM , _qN , and _qS are integer values determined so that the slit number S _M of the first track can finally be calculated. For example, if the first number N _M =16, the second number N _N =15, and the third number N _S =12, then ( _pM , _pN , _pS ) = (3, -4, 1) and ( _qM , _qN , _qS ) = (3, 0, -4) may be set. In this way, each slit position signal calculation unit 1330 can calculate each slit position signal by weighting the multiple detection values from the multiple detection units 1320 by predetermined integers and taking the sum.

The slit number calculation unit 1340 is connected to the plurality of slit position signal calculation units 1330. The slit number calculation unit 1340 calculates a slit number S _M (i.e., the slit number of the slit where the moving object 1301 is located) in units of first slits of a predetermined size, using the slit position signals S _MSB and S _LSB output by the plurality of slit position signal calculation units 1330. In this embodiment, the slit number calculation unit 1340 calculates the slit number S _M using the following equation (6):

Here, k is a positive integer value indicating the weight of the MSB. The slit number calculation unit 1340 can calculate the slit number in first slit units by adding a value obtained by rounding off _{the MSB} of the first slit position signal S to the value obtained by multiplying the result by the MSB weight _k . The slit number calculation unit 1340 can calculate the slit number in first slit units by normalizing this slit number to a value from 0 to N _M -1.

Note that k can be uniquely determined according to the values of p and q so that the slit number S _M can be calculated. For example, when (p _M , p _N , p _S ) = (3, -4, 1) and (q _M , q _N , q _S ) = (0, 4, -5), k = 5 may be used. The set of k, p, and q may be determined to satisfy the relationships (p _M , p _N , p _S ) = (3, -4, 1) and (q _M , q _N , q _S ) = (3, 0, -4) - (k - 4) x (p _M , p _N , p _S ). Here, the smaller the absolute value of q (the magnitude of the q vector), the more robust it is against slit identification errors, so from this perspective, k = 4 may be used.

The detected position of the moving body 1301 before the slit number is corrected is expressed as a pair of the slit number S _M and the interpolation angle θ _M. In this modification, the mechanical angle θ _d , which is an example of the detected position, is expressed by the above-described formula (1), similar to the encoder 110.

The correction table 1350 is connected to the detection unit 1320a and the slit number calculation unit 1340. The correction table 1350 stores, for each slit number, a set of a correction value S _Mcal for the first slit position signal S _MSB and a correction value S Lcal for the second slit position signal S _LSB according to the first detection signal (interpolation angle θ _M ) detected from the first track. The correction table 1350 outputs the correction values S _Mcal and S _Lcal corresponding to the first detection signal from the set of correction values associated with the slit number S _M received from the slit _number calculation unit 1340.

The slit number correction unit 1360 is connected to the plurality of slit position signal calculation units 1330 and the correction table 1350. The slit number correction unit 1360 corrects the plurality of slit position signals S _MSB and S _LSB received from the slit position signal calculation unit 1330 using the correction values S _Mcal and S _Lcal received from the correction table 150. Then, the slit number correction unit 160 calculates the corrected slit number S' _M based on the plurality of corrected slit position signals. In this modification, the slit number correction unit 1360 calculates the corrected slit number S' _M using the following equation (7):

Note that equation (7) is obtained by replacing the slit position signals S _MSB and S _LSB in equation (6) with corrected slit position signals S _MSB +S _Mcal and S _LSB +S _Lcal , respectively.

The position calculation unit 1370 is connected to the detection unit 1320a and the slit number correction unit 1360. The position calculation unit 1370 calculates the position (corrected position) of the moving body 1301 in the same manner as the position calculation unit 170 in FIG. 1. In this modified example, the position calculation unit 1370 outputs the mechanical angle θ, with one rotation of the moving body 1301 being one period, as a value indicating the position of the moving body 1301.

14 shows an example of ideal values of the first slit position signal S _MSB according to a modification of this embodiment. This figure plots the first slit position signal S MSB shown in equation (4) for the cases where the first number N _M =16, the second number N _N =15, and the third number N _S =12, and (p _M , p _N , p _S )=(3, −4, 1). The first slit position signal S _MSB can change depending on the values of the coefficients p _M , p _N , and p _S , but in this modification, it changes roughly corresponding to the most significant digit of the slit number _, as shown in FIG.

15 shows an example of ideal values of the second slit position signal S _LSB according to a modification of this embodiment. This figure plots the second slit position signal S LSB shown in equation (5) for the cases where the first number N _M =16, the second number N _N =15, and the third number N _S =12, and (q _M , q _N , q _S )=(3, 0, -4). The second slit position signal S _LSB can vary depending on the values of the coefficients q _M , q _N , and q _S , but in this modification, it varies roughly corresponding to the lower digits of the slit number _, as shown in FIG.

Fig. 16 shows an example of ideal values of slit numbers according to a modification of this embodiment. This figure plots the slit number S _M shown in equation (6) using the first slit position signal S _MSB shown in Fig. 14 and the second slit position signal S _LSB shown in Fig. 15. In this modification, by using the first slit position signal S _MSB shown in Fig. 14 and the second slit position signal S _LSB shown in Fig. 15, the slit number is obtained such that the slit number increases by 1 from 0 to 15 (i.e., N _M -1) every time the ideal mechanical angle of the moving body 1301 changes by 22.5° (i.e., 360°/N _M ) from 0° to 360°.

Next, calibration of the position detection device 1300 shown in Figures 13 to 16 will be described. In this modification, the calibration device 700 may generate a correction value S _Mcal of the first slit position signal S MSB and a correction value S _Lcal of the second slit position signal S _LSB in the same manner as generating the correction value S _cal of the slit position signal _SS as shown in Figures 7 and 8. More specifically, the acquisition unit 710 acquires the detected position of the moving body 1301 for each actual position of the moving body 1301, similar to S800 in Figure 8.

Here, the acquiring unit 710 acquires, from the encoder used as a calibration reference, S _MSB ideal, which indicates an ideal value of the first slit position signal S _MSB and which corresponds to the most significant digit of the slit number of the actual position; S _LSB ideal, which indicates an ideal value of the second slit position signal S _LSB and which corresponds to the least significant digit of the slit number of the actual position; and θ _Mideal , which indicates an interpolation angle of the actual position, as values indicating the actual position of the moving object 1301. The acquiring unit 710 also acquires, from the encoder 1310, the first slit position signal S _MSB , the second slit position signal S _LSB , and the interpolation angle θ _M as the detected position of the moving object 1301. The generating unit 720 converts the data format of the data in which the detected position is associated with each actual position of the moving object 1301, to obtain data in which one or more actual positions are associated with each detected position of the moving object 1301.

As in FIG. 8, the calculation unit 714, the determination unit 716, and the generation unit 720 repeat the processes from S810 to S860 for each of the first slit position signal S _MSB and the second slit position signal S _LSB for each detected position of the moving object 1301.

Regarding the first slit position signal S _MSB , the determination unit 716 determines whether two or more real positions, which have at least a partial difference in the slit number in the most significant digit, which is the unit of the first slit position signal S _MSB , correspond to the same detection position, as in S820 of FIG. 8. If only one real position corresponds to the target detection position ("N" in S830), the generation unit 720 generates a correction value S _Mcal for the first slit position signal S _MSB , which corrects for the error at that one real position (i.e., S _MSB - S _{MSB ideal} ) at that detection position, as in S840. If two or more real positions, which have at least a partial difference in the slit number, correspond to the target detection position ("Y" in S830), the generation unit 720 generates a correction value S _Mcal for correcting the magnitude of the difference between the errors at the two or more real positions at that detection position, as in S850. For the second slit position signal S _LSB as well, the generation section 720 generates a correction value S _Lcal at the target detection position in the same manner as above.

8, the inspection unit 730 inspects whether or not an error occurs in the upper slit number calculated using the slit position signal corrected by the correction value S _Mcal generated by the generation unit 720 for the first slit position signal S _MSB . Also, the inspection unit 730 inspects whether or not an error occurs in the lower slit number calculated using the slit position signal corrected by the correction value S _Lcal generated by the generation unit 720 for the second slit position signal S _LSB .

Similar to S880 in Figure 8, the output unit 740 outputs the correction values for each inspection position and each of the first and second slit position signals generated by the generation unit 720.

The calibration device 700 according to this modified example can generate correction values that appropriately correct the track number in the encoder 1310 that detects the position of a moving body 1301 using a moving body 1301 with three tracks. Similarly, the calibration device 700 can also output correction values for an encoder that detects the position of a moving body with four or more tracks, that correct each of one or more slit position signals calculated by the weighted sum of multiple detection values detected from multiple tracks.

Various embodiments of the present invention may be described with reference to flowcharts and block diagrams, where the blocks may represent (1) stages of a process in which operations are performed or (2) sections of apparatus responsible for performing the operations. Particular stages and sections may be implemented by dedicated circuitry, programmable circuitry supplied with computer-readable instructions stored on a computer-readable medium, and/or a processor supplied with computer-readable instructions stored on a computer-readable medium. Dedicated circuitry may include digital and/or analog hardware circuitry and may include integrated circuits (ICs) and/or discrete circuits. Programmable circuitry may include reconfigurable hardware circuitry including logical AND, logical OR, logical XOR, logical NAND, logical NOR, and other logical operations, flip-flops, registers, memory elements such as field programmable gate arrays (FPGAs), programmable logic arrays (PLAs), etc.

A computer-readable medium may include any tangible device capable of storing instructions that are executed by a suitable device, such that the computer-readable medium having instructions stored thereon comprises an article of manufacture, including instructions that can be executed to create means for performing the operations specified in the flowchart or block diagram. Examples of computer-readable media may include electronic storage media, magnetic storage media, optical storage media, electromagnetic storage media, semiconductor storage media, etc. More specific examples of computer-readable media may include floppy disks, diskettes, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), electrically erasable programmable read-only memory (EEPROM), static random access memory (SRAM), compact disc read-only memory (CD-ROM), digital versatile disc (DVD), Blu-ray disc, memory stick, integrated circuit card, etc.

The computer-readable instructions may include either assembler instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state-setting data, or source or object code written in any combination of one or more programming languages, including object-oriented programming languages such as JAVA (registered trademark), C++, Smalltalk (registered trademark), etc., and conventional procedural programming languages such as the "C" programming language or similar programming languages.

The computer-readable instructions may be provided to a processor or programmable circuitry of a programmable data processing apparatus, such as a general-purpose computer, special-purpose computer, or other computer, either locally or over a wide-area network (WAN) such as a local area network (LAN), the Internet, etc., which executes the computer-readable instructions to create means for performing the operations specified in the flowcharts or block diagrams. Examples of processors include computer processors, processing units, microprocessors, digital signal processors, controllers, microcontrollers, etc.

Figure 17 shows an example of a computer 2200 in which aspects of the present invention may be embodied, in whole or in part. Programs installed on the computer 2200 may cause the computer 2200 to function as or perform operations associated with an apparatus or one or more sections of the apparatus according to embodiments of the present invention, and/or to perform a process or steps of a process according to embodiments of the present invention. Such programs may be executed by the CPU 2212 to cause the computer 2200 to perform specific operations associated with some or all of the blocks in the flowcharts and block diagrams described herein.

The computer 2200 according to this embodiment includes a CPU 2212, RAM 2214, a graphics controller 2216, and a display device 2218, which are interconnected by a host controller 2210. The computer 2200 also includes input/output units such as a communications interface 2222, a hard disk drive 2224, a DVD-ROM drive 2226, and an IC card drive, which are connected to the host controller 2210 via an input/output controller 2220. The computer also includes legacy input/output units such as a ROM 2230 and a keyboard 2242, which are connected to the input/output controller 2220 via an input/output chip 2240.

The CPU 2212 operates according to programs stored in the ROM 2230 and RAM 2214, thereby controlling each unit. The graphics controller 2216 retrieves image data generated by the CPU 2212 into a frame buffer or the like provided in the RAM 2214 or into the graphics controller itself, and causes the image data to be displayed on the display device 2218.

The communications interface 2222 communicates with other electronic devices via a network. The hard disk drive 2224 stores programs and data used by the CPU 2212 in the computer 2200. The DVD-ROM drive 2226 reads programs or data from the DVD-ROM 2201 and provides the programs or data to the hard disk drive 2224 via the RAM 2214. The IC card drive reads programs and data from an IC card and/or writes programs and data to an IC card.

ROM 2230 stores therein boot programs and the like that are executed by computer 2200 upon activation, and/or programs that depend on the hardware of computer 2200. I/O chip 2240 may also connect various I/O units to I/O controller 2220 via parallel ports, serial ports, keyboard ports, mouse ports, etc.

The programs are provided on a computer-readable medium such as a DVD-ROM 2201 or an IC card. The programs are read from the computer-readable medium, installed on the hard disk drive 2224, RAM 2214, or ROM 2230, which are also examples of computer-readable media, and executed by the CPU 2212. The information processing described in these programs is read by the computer 2200, resulting in cooperation between the programs and the various types of hardware resources described above. An apparatus or method may be configured by implementing information manipulation or processing in accordance with the use of the computer 2200.

For example, when communication is performed between computer 2200 and an external device, CPU 2212 may execute a communication program loaded into RAM 2214 and instruct communication interface 2222 to perform communication processing based on the processing described in the communication program. Under the control of CPU 2212, communication interface 2222 reads transmission data stored in a transmission buffer processing area provided in RAM 2214, hard disk drive 2224, DVD-ROM 2201, or a recording medium such as an IC card, and transmits the read transmission data to the network, or writes received data received from the network to a reception buffer processing area, etc., provided on the recording medium.

The CPU 2212 may also cause all or necessary portions of a file or database stored on an external recording medium such as the hard disk drive 2224, DVD-ROM drive 2226 (DVD-ROM 2201), IC card, etc. to be read into the RAM 2214, and perform various types of processing on the data on the RAM 2214. The CPU 2212 then writes the processed data back to the external recording medium.

Various types of information, such as various types of programs, data, tables, and databases, may be stored on the recording medium and may undergo information processing. CPU 2212 may perform various types of processing on data read from RAM 2214, including various types of operations, information processing, conditional judgment, conditional branching, unconditional branching, information search/replacement, etc., as described throughout this disclosure and specified by the program's instruction sequence, and write the results back to RAM 2214. CPU 2212 may also search for information in files, databases, etc. on the recording medium. For example, if multiple entries, each having an attribute value of a first attribute associated with an attribute value of a second attribute, are stored on the recording medium, CPU 2212 may search for an entry that matches a condition specified by the attribute value of the first attribute from among the multiple entries, read the attribute value of the second attribute stored in the entry, and thereby obtain the attribute value of the second attribute associated with the first attribute that satisfies a predetermined condition.

The programs or software modules described above may be stored on computer-readable media on or near computer 2200. Recording media such as a hard disk or RAM provided within a server system connected to a dedicated communications network or the Internet can also be used as computer-readable media, thereby providing the programs to computer 2200 via the network.

The present invention has been described above using embodiments, but the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be clear to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention.

The order of execution of each process, such as operations, procedures, steps, and stages, in the devices, systems, programs, and methods shown in the claims, specifications, and drawings is not specifically stated as "before," "prior to," or the like, and it should be noted that processes can be performed in any order, unless the output of a previous process is used in a subsequent process. Even if the operational flow in the claims, specifications, and drawings is described using "first," "next," etc. for convenience, this does not mean that it is necessary to perform the processes in that order.

10 Position detection device 100 Moving body 105a-b Track 110 Encoder 120a-b Detection unit 130 Slit position signal calculation unit 140 Slit number calculation unit 150 Correction table 160 Slit number correction unit 170 Position calculation unit 500a-e Error 600a-e Error 610 Error 700 Calibration device 710 Acquisition unit 714 Calculation unit 716 Determination unit 720 Generation unit 730 Inspection unit 740 Output unit 1300 Position detection device 1301 Moving body 1310 Encoder 1320a-b Detection unit 1330 Slit position signal calculation unit 1340 Slit number calculation unit 1350 Correction table 1360 Slit number correction unit 1370 Position calculation unit 2200 Computer 2201 DVD-ROM
2210 host controller 2212 CPU
2214 RAM
2216 Graphics controller 2218 Display device 2220 Input/output controller 2222 Communication interface 2224 Hard disk drive 2226 DVD-ROM drive 2230 ROM
2240 Input/Output Chip 2242 Keyboard

Claims (16)

an acquisition unit that acquires a detected position of a moving object for each actual position of the moving object;
a calculation unit that calculates an error between a slit position signal that detects a slit position and an ideal slit number that corresponds to the actual position of the moving body, for a detected position for each actual position of the moving body;
a determination unit that determines whether or not two or more actual positions having at least some different slit numbers, each of which is based on a first slit of a predetermined size, correspond to the same detected position;
a generation unit that generates a correction value at the detection position to correct a magnitude of a difference between errors at the two or more actual positions for the slit position signal in response to the two or more actual positions corresponding to the same detection position. The calibration device described in claim 1, wherein the generation unit generates a correction value for the slit position signal in response to the fact that only one real position corresponds to a certain detection position, thereby correcting an error in the one real position at that detection position. The calibration device described in claim 1, wherein the generation unit generates a correction value for each section of the detection position acquired by the acquisition unit. The calibration device described in claim 1, wherein the generation unit calculates parameters of a correction function that represents a correction value corresponding to the detection position for each section of the detection position acquired by the acquisition unit. The calibration device described in claim 4, wherein the generation unit calculates the parameters of the correction function by performing a Fourier series expansion on a set of correction values corresponding to each detection position acquired by the acquisition unit for each section of the detection position. The calibration device described in claim 1, wherein the generation unit generates a correction value that corrects the slit position signal by an average magnitude of errors at each of the two or more actual positions, in response to the two or more actual positions corresponding to the same detection position. The calibration device described in claim 1, wherein the determination unit determines the correspondence between the actual position and the detected position by providing a margin at the boundary of the first slit. The calibration device described in claim 7, wherein the generation unit generates a correction value using at least one actual position corresponding to the detected position, the actual position being obtained by adding or subtracting a predetermined margin to the boundary of the first slit from the slit position signal. The calibration device of claim 1 further comprises an output unit that outputs a correction value to an encoder that calculates a slit number in units of the first slit by adding a correction value to the slit position signal and rounding off the result. The calibration device described in claim 9, wherein the encoder calculates the slit number by rounding off the value obtained by adding a correction value to the slit position signal to an integer. The calibration device described in claim 9, wherein the output unit writes the correction value into a correction table provided in the encoder. The calibration device of claim 9, further comprising an inspection unit that inspects whether an error occurs in the slit number calculated using the slit position signal corrected by the correction value generated by the generation unit. the moving body is a rotating body,
The rotating body is
a first track including the first slits for each first period obtained by dividing one revolution of the rotating body by a predetermined first number;
a second track including second slits at second intervals obtained by dividing one revolution of the rotating body by a second number smaller than the first number,
13. The calibration device according to claim 1, wherein the encoder to be calibrated calculates the detected position of the moving object based on a first detection value detected from the first track and a second detection value detected from the second track. the rotating body further includes a third track including third slits for each third period obtained by dividing one revolution of the rotating body by a third number different from the first number and the second number,
The calibration device according to claim 13 , wherein the encoder calculates the detected position of the moving object further based on a third detected value detected from the third track. a calibration device acquiring a detected position of the moving object for each actual position of the moving object;
the calibration device calculates an error between a slit position signal that detects a slit position and an ideal slit number that corresponds to the actual position of the moving body, for a detected position for each actual position of the moving body;
the calibration device determines whether or not two or more actual positions having at least some different slit numbers, each of which is based on a first slit of a predetermined size, correspond to the same detected position;
and generating, in response to the two or more actual positions corresponding to the same detection position, a correction value at the detection position that corrects the slit position signal for a magnitude difference between errors at the two or more actual positions. The method is executed by a computer, causing the computer to:
an acquisition unit that acquires a detected position of a moving object for each actual position of the moving object;
a calculation unit that calculates an error between a slit position signal that detects a slit position and an ideal slit number that corresponds to the actual position of the moving body, for a detected position for each actual position of the moving body;
a determination unit that determines whether two or more actual positions having at least some different slit numbers, each of which is based on a first slit of a predetermined size, correspond to the same detected position;
a calibration program that causes the program to function as a generation unit that generates, in response to the two or more actual positions corresponding to the same detection position, a correction value that corrects the magnitude of the difference between errors at the two or more actual positions for the slit position signal at the detection position.