Position information correction device and method for linear motor

Abstract

To provide a position information correction device capable of effectively correcting position information of a linear motor detected by a position detector.SOLUTION: A position information correction device includes: a memory 23 for storing previously measured position-dependent and speed-dependent errors components; a position-dependent error correction unit 22a for reading a position-dependent error component corresponding to position information P from a position detector 12 from a memory 23 to correct the position information P by using the position-dependent error component; and a speed-dependent error correction unit 22b for reading the speed-dependent error component corresponding to the position information P from the position detector 12 from the memory 23 to correct the position information P by using the speed-dependent error component and speed information of a linear motor.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a position information correction device and method for correcting position information of a linear motor detected by a position detector. [Background technology]

[0002] A position detector (encoder) is used to detect the position of the mover of a linear motor. The encoder is equipped with a scale and a sensor that detects the magnetic flux of the scale. As the mover of the linear motor moves linearly, the sensor outputs a sine wave signal and a cosine wave signal that are out of phase with each other by 90 degrees. These sine wave signal and cosine wave signal are A / D converted and then output to the encoder's interpolator. The interpolator derives tangent from the digitally converted sine wave signal and cosine wave signal. -1 The position information of the linear motor is detected using θ. The position information detected by the encoder is output to a control device that controls the linear motor.

[0003] The sine wave and cosine wave signals output by the encoder head sensor contain distortion. As a result, position information of the linear motor detected by the encoder is superimposed with a position error. If a linear motor is controlled using position information with a superimposed position error, it is as if the linear motor were controlled using a scale with coarse and fine graduations, which causes thrust pulsation in the linear motor.

[0004] In order to reduce the position error, Patent Document 1 discloses a method for correcting rotational position information detected by a rotary encoder. In this method, a position-dependent error measured in advance is stored in a memory, and the position-dependent error corresponding to the rotational position information detected by the rotary encoder is read from the memory, and the position-dependent error is used to correct the position information. Specifically, the position-dependent error is added to the rotational position information detected by the rotary encoder. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 5-231879 Summary of the Invention [Problem to be solved by the invention]

[0006] When the mover of a linear motor is moved linearly, the position error superimposed on the position information of the linear motor includes not only an error component dependent on the position (hereinafter referred to as a position-dependent error component) but also an error component dependent on the speed (hereinafter referred to as a speed-dependent error component). As described in Patent Document 1, even if the position information is corrected using only the position-dependent error component, the position information of the linear motor cannot be effectively corrected.

[0007] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a position information correction device and method that can effectively correct the position information of a linear motor detected by a position detector. [Means for solving the problem]

[0008] In order to solve the above problems, one aspect of the present invention is a position information correction device that corrects position information of a linear motor detected by a position detector, the device comprising: a memory that stores previously measured position-dependent error components and speed-dependent error components; a position-dependent error correction unit that reads from the memory a position-dependent error component corresponding to the position information from the position detector and corrects the position information using this position-dependent error component; and a speed-dependent error correction unit that reads from the memory a speed-dependent error component corresponding to the position information from the position detector and corrects the position information using this speed-dependent error component and speed information of the linear motor.

[0009] Another aspect of the present invention is a position information correction method for correcting position information of a linear motor detected by a position detector, comprising the steps of: reading a position-dependent error component corresponding to the position information detected by the position detector from position-dependent error components measured in advance and stored in a memory, and correcting the position information using this position-dependent error component; and reading a speed-dependent error component corresponding to the position information detected by the position detector from speed-dependent error components measured in advance and stored in a memory, and correcting the position information using this speed-dependent error component and speed information of the linear motor. Effect of the Invention

[0010] According to the present invention, the position information of the linear motor detected by the position detector can be effectively corrected using the position-dependent error component and the speed-dependent error component stored in the memory. [Brief description of the drawings]

[0011] [Figure 1] 1 is a perspective view (including a partial cross-sectional view) of a linear motor to which a position information correction device according to a first embodiment of the present invention is applied. [Diagram 2] FIG. 2 is a front view of the linear motor. [Diagram 3] 1 is an external view of an encoder head in which a position information correction device according to an embodiment of the present invention is incorporated. [Figure 4] FIG. 2 is a diagram illustrating the configuration of the encoder head. [Diagram 5] 1 is a functional block diagram of a position information correction device according to an embodiment of the present invention. [Figure 6] FIG. 13 is a diagram showing a position-dependent error table. [Figure 7] FIG. 13 is a diagram showing a speed-dependent error table. [Figure 8] 4 is a flowchart illustrating a position correction method according to the present embodiment. [Figure 9] FIG. 11 is a configuration diagram of a driver in which a position information correction device according to a second embodiment of the present invention is incorporated. [Figure 10]1 is a conceptual diagram illustrating a method for measuring a position-dependent error component and a velocity-dependent error component. [Figure 11] 4 is a graph showing a detected position error. [Figure 12] 11 is a graph showing the waveform of a position-dependent error component. [Figure 13] 4 is a graph showing a waveform of a speed-dependent error component. [Figure 14] 14 is a graph showing waveforms when the speed is 300 mm / s and when the speed is 400 mm / s extracted from the waveforms of the speed-dependent error components shown in FIG. 13. [Figure 15] 11 is a graph showing a position error after the position information is corrected using a position-dependent error component and a velocity-dependent error component. [Figure 16] 1 is a graph comparing thrust forces generated in linear motors. [Figure 17] 4 is a graph showing a waveform of a speed-dependent error component. [Figure 18] 13 is a graph showing a waveform of a representative speed-dependent error component. [Figure 19] 11 is a graph showing a waveform obtained by applying a filter to the waveform of a position-dependent error component. [Figure 20] 13 is a graph showing pulsation components extracted from position-dependent error components. [Figure 21] 13 is a graph showing the waveform of a representative position-dependent error component. [Figure 22] 1 is a graph comparing thrust forces generated in linear motors. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, a position information correction device and method according to an embodiment of the present invention will be described with reference to the accompanying drawings. However, the position information correction device and method according to the present invention can be embodied in various forms and are not limited to the embodiments described in this specification. The present embodiment is provided with the intention of enabling a person skilled in the art to fully understand the invention by fully disclosing the specification. (Linear motor)

[0013] 1 and 2 show a linear motor 1 to which a position information correction device according to a first embodiment of the present invention is applied. In FIG. 1, a table 4 is shown in cross section to show the internal structure of the linear motor 1. The linear motor 1 includes a stator 2 and a mover 3 that moves linearly relative to the stator 2. The stator 2 includes a base 5, a yoke 6 (see FIG. 2) fixed to the base 5, and a plurality of drive magnets 7 linearly arranged on the yoke 6. On the upper surfaces of the plurality of drive magnets 7, N poles and S poles are formed alternately in the longitudinal direction of the linear motor 1. The mover 3 includes a table 4 and an armature 8 fixed to the table 4. An armature coil is attached to the armature 8. When a three-phase AC current is supplied to the armature coil, a thrust is generated in the mover 3 due to the interaction between the moving magnetic field generated in the armature coil and the magnetic field of the drive magnet 7. In FIG. 1, reference numeral 9 denotes a linear guide, reference numeral 10 denotes a guide rail, and reference numeral 11 denotes a carriage. In FIG. 2, reference numeral 12 denotes an encoder head of a position detector (hereinafter, referred to as an encoder). The driving magnet 7 of the linear motor 1 also serves as a scale for an encoder, and an encoder head 12 detects the magnetic flux of the driving magnet 7 . (Encoder head equipped with the position information correction device according to the first embodiment of the present invention)

[0014] Fig. 3 shows an external view of the encoder head 12 in which the position information correction device of this embodiment is incorporated. As shown in Fig. 3, the encoder head 12 detects the magnetic flux of the drive magnet 7, and detects the position information of the linear motor 1 based on the magnetic flux of the drive magnet 7. The position information detected by the encoder head 12 is input to a control device (hereinafter referred to as a driver 31; see Fig. 4) that controls the linear motor 1. Reference numeral 12a denotes a terminal connected to the driver 31.

[0015] Fig. 4 shows a configuration diagram of the encoder head 12. As shown in Fig. 4, the position information correction device 21 of this embodiment includes a position-dependent error correction unit (microcontroller 22), a speed-dependent error correction unit (microcontroller 22), and a memory 23. The position-dependent error correction unit and the speed-dependent error correction unit are realized by a processor of the microcontroller 22 (MCU) of the encoder head 12 executing a program stored in a ROM. Note that instead of the microcontroller 22, a DSP, an ASIC, or the like, or an electric circuit may be used.

[0016] The magnetic sensor 24 of the encoder head 12 is an MR element, a Hall element, or the like, and outputs a two-phase analog signal having a phase difference of π / 2 as the table 4 of the linear motor 1 moves. The two-phase analog signal output by the magnetic sensor 24 is input to an interpolator 26 via a filter 25. The magnetic sensor 28 is an MR element, a Hall element, or the like, and is used to detect the electrical angle of the linear motor 1. The output of the magnetic sensor 28 is input to the microcontroller 22 via a filter 30. The origin sensor 29 is a Hall element, or the like, and is used to detect the origin position of the mover 3 of the linear motor 1. The output of the origin sensor 29 is input to the microcontroller 22.

[0017] The interpolator 26 converts the two-phase analog signal output by the magnetic sensor 24 into a digital signal, and calculates tangent -1 Using θ, position information of the linear motor 1 is detected. The sine wave signal and cosine wave signal output by the magnetic sensor 24 contain distortion. Therefore, a position error is superimposed on the position information of the linear motor 1 detected by the interpolator 26. In order to reduce the position error, a position information correction device 21 is provided.

[0018] The position error includes not only a position-dependent error component but also a velocity-dependent error component. Therefore, the position-dependent error component and the velocity-dependent error component are measured in advance and stored in the memory 23. The method of measuring the position-dependent error component and the velocity-dependent error component will be described later. The memory 23 is a non-volatile memory such as a PROM or an EPROM.

[0019] The position-dependent error component and the speed-dependent error component have the characteristic of periodically changing with the magnet pitch of the drive magnet 7 (the north-north pole pitch L1 or the north-south pole pitch L2 in FIG. 3). Focusing on this characteristic, as shown in FIG. 6, the representative position-dependent error component α P is calculated and stored in the memory 23. Similarly, as shown in FIG. 7, the representative speed-dependent error component β P is calculated and stored in the memory 23.

[0020] As shown in the functional block diagram of FIG. 5, the position-dependent error correction unit 22a calculates a representative position-dependent error component α P is read from the position-dependent error table 23a, and the representative position-dependent error component α P The speed-dependent error correction unit 22b corrects the position information P using the representative speed-dependent error component β P is read from the speed-dependent error table 23b, and the representative speed-dependent error component β P and the speed information V of the linear motor 1 are used to correct the position information.

[0021] A method of correcting such position information P will be described with reference to the flowchart of Fig. 8. As shown in Fig. 8, first, the interpolator 26 detects the position information P of the linear motor 1 (S1). When the position information of the linear motor 1 sent from the interpolator 26 is P, the position-dependent error correction unit 22a calculates a representative position-dependent error component α P is read from the position-dependent error table 23a. Then, the representative position-dependent error component α P Adding this, the position information P' (P' = P + α P When the position information P is an intermediate value between P1 and P2, the position-dependent error correction unit 22a calculates the representative position-dependent error component α P1 ,α P2is read, and an interpolation operation is performed to obtain a representative position-dependent error component corresponding to the intermediate value between P1 and P2.

[0022] When the position information of the linear motor 1 sent from the interpolator 26 is P, the speed-dependent error correction unit 22b calculates a representative speed-dependent error component β P is read from the speed-dependent error table 23b. Then, the representative speed-dependent error component β P is multiplied by the speed information V of linear motor 1, V × β P Add to the position information P' to get the position information P'' (P'' = P + α P +V×β P ) is calculated (S3). This position information P'' is output to the driver 31 via the communication interface 27 (see FIG. 4). When the position information P is an intermediate value between P1 and P2, the speed-dependent error correction unit 22b calculates the representative speed-dependent error component β P1 ,β P2 is read and an interpolation is performed to obtain the representative speed-dependent error component corresponding to the intermediate value between P1 and P2. (Driver equipped with a position information correction device according to the second embodiment of the present invention)

[0023] Fig. 9 shows a configuration diagram of the driver 51. As shown in Fig. 9, a position information correction device 41 according to the second embodiment of the present invention is incorporated into the driver 51. The position information correction device 41 includes a position-dependent error correction unit (microcontroller 42), a speed-dependent error correction unit (microcontroller 42), and a memory 43. The position-dependent error correction unit and the speed-dependent error correction unit are realized by the processor of the microcontroller 42 executing a program stored in the ROM. Note that instead of the microcontroller 42, a DSP, an ASIC, or an electric circuit may be used.

[0024] The memory 43 is a non-volatile memory such as a PROM or an EPROM. The memory 43 stores position-dependent error components and speed-dependent error components that have been measured in advance. As shown in FIG. 6, the position-dependent error components are a representative position-dependent error component α P As shown in FIG. 7, the speed-dependent error component is a representative speed-dependent error component β P It is.

[0025] As shown in FIG. 9, the position-dependent error correction unit calculates a representative position-dependent error component α P is read from the memory 43, and the representative position-dependent error component α P The speed-dependent error correction unit corrects the position information P using the representative speed-dependent error component β P is read from the memory 43, and the representative speed-dependent error component β P and the speed information V of the linear motor 1. The correction method by the position-dependent error correction unit and the speed-dependent error correction unit is the same as that shown in the flowchart of FIG.

[0026] After calculating the corrected position information P'', the microcontroller 42 performs feedback control so that the corrected position information P'' follows the position command input from the higher-level control device via the communication interface 47, and outputs a gate signal. Based on this gate signal, the power converter 44 converts the power provided from the power supply circuit 45 into a drive current to be supplied to the linear motor 1. A PWM inverter is usually used for the power converter 44. An A / D converter 46 is provided on the input side of the microcontroller 42, which converts an analog signal of a current sensor 48 that detects the current of the linear motor 1 into a digital signal.

[0027] The memory 43 is provided in the encoder 30, and when the driver 51 is started, the encoder 30 transmits the representative position-dependent error component α P and representative speed-dependent error component β PAlternatively, the data may be transmitted and the driver 51 may perform the correction. (Method of measuring position-dependent error components and velocity-dependent error components)

[0028] A method for measuring the position-dependent error component and the speed-dependent error component will be described below. In Fig. 10, reference numeral 1 denotes a linear motor, reference numeral 12 denotes an encoder head incorporating a position information correction device 21 according to the first embodiment of the present invention, reference numeral 31 denotes a driver for controlling the linear motor 1, reference numeral 33 denotes a reference scale (reference measuring device) such as a laser length measuring instrument, reference numeral 32 denotes a trigger device for synchronizing the reference measuring device 33 with the encoder head 12, and reference numeral 34 denotes a computer that subtracts the position information detected by the encoder head 12 from the reference position information measured by the reference measuring device 33 to determine the position error.

[0029] First, the driver 31 moves the table 4 of the linear motor 1 at a constant speed using the uncorrected position information detected by the encoder head 12. At the same time, the reference measurement device 33 is used to obtain the actual position (reference position information) of the table 4 of the linear motor 1. The position error can be found by subtracting the uncorrected position information detected by the encoder from the reference position information.

[0030] FIG. 11 shows an example of a detected position error. The vertical axis of FIG. 11 is the position error (=reference position information-position information before correction detected by encoder head 12). The horizontal axis of FIG. 11 is the displacement of table 4 of linear motor 1 measured by reference measuring device 33. In FIG. 11, the speed of linear motor 1 is changed from 10 mm / s to 1500 mm / s. The upper waveform is the waveform of the position error on the outbound path, and the lower waveform is the waveform of the position error on the return path.

[0031] As shown in Figure 11, the position error increases as the speed of the linear motor 1 increases. On the other hand, when the speed of the linear motor 1 is, for example, 10 mm / s (15 mm / s or less), the position error consists almost entirely of position-dependent error components, with no speed-dependent error components. This shows that the position error consists of position-dependent error components and speed-dependent error components.

[0032] Fig. 12 shows the waveforms of the position error in the forward and backward movements when the speed is 10 mm / s. As shown in Fig. 12, when the speed is 10 mm / s, there is a slight difference between the waveforms of the position error in the forward and backward movements, but they are almost the same. In this embodiment, the waveforms of the position error in the forward and backward movements when the speed is 10 mm / s are averaged to obtain the waveform of the position-dependent error component. The waveform of this position-dependent error component is used to correct the position-dependent error component.

[0033] Figure 13 shows the waveform obtained by subtracting the position-dependent error waveform shown in Figure 12 from the position error waveform shown in Figure 11, i.e., the waveform after correcting the position-dependent error component. As shown in Figure 13, when the position-dependent error component is corrected, the waveform of the velocity-dependent error component can be confirmed. It can be seen that the amplitude of the velocity-dependent error component waveform increases in proportion to the velocity.

[0034] Figure 14 shows the waveforms of the speed-dependent error component when the speed is 300 mm / s and 400 mm / s. When the waveform for 300 mm / s is multiplied by a speed ratio of 4 / 3, it approximately matches the waveform for 400 mm / s. This shows that the waveform of the speed-dependent error component has a fixed shape, and the amplitude has characteristics that are proportional to the speed.

[0035] For this reason, in this embodiment, the waveform of the speed-dependent error component is obtained by dividing the difference between pre-correction position information detected by the encoder head 12 when the table 4 of the linear motor 1 is moved at high speed (e.g., 400 mm / s) and pre-correction position information detected by the encoder head 12 when the table 4 of the linear motor 1 is moved at low speed (e.g., 300 m / s) by the speed difference (400 m / s-300 m / s). The waveform of the speed-dependent error component may be obtained using the pre-correction position information detected by the encoder head 12 when the linear motor 1 is moved at high speed (e.g., 300 mm / s) and low speed (e.g., 10 mm / s). (Position information correction using position-dependent error components and velocity-dependent error components)

[0036] 15 shows the position error when the position information is corrected using the position-dependent error component and the speed-dependent error component. It can be seen that by correcting the position information using the position-dependent error component and the speed-dependent error component, the position error can be significantly improved regardless of the speed of the linear motor 1.

[0037] Figure 16 is a graph comparing the thrust generated in linear motor 1 when linear motor 1 is controlled using reference position information detected by reference measuring device 33 (reference scale), when linear motor 1 is controlled using uncorrected position information detected by encoder head 12 (before correction), and when linear motor 1 is controlled using position information in which the position-dependent error components and velocity-dependent error components have been corrected (position-dependent error correction + velocity-dependent error correction).

[0038] As shown in Figure 16, when the linear motor 1 is controlled using the uncorrected position information detected by the encoder head 12, thrust pulsation occurs especially in the constant velocity portion. This is because the linear motor 1 is controlled as if a scale with fine and coarse markings was used. This thrust pulsation causes vibration, noise, motor heat, etc. As shown in Figure 16, by correcting the position information using the position-dependent error component and the speed-dependent error component, it is possible to significantly reduce the thrust pulsation that occurred before correction. (Representative speed dependent error component)

[0039] As shown in Fig. 17, the waveform of the speed-dependent error component changes periodically at 39 mm, which is the magnet pitch of the drive magnet 7. Two scale marks on the horizontal axis in Fig. 17 indicate the magnet pitch. In this embodiment, as shown in Fig. 18, the waveform of the speed-dependent error component in the constant speed section is averaged by the magnet pitch and divided by the speed information V of the linear motor 1 to obtain the waveform of the representative speed-dependent error component. Fig. 7 is a table of the waveforms of the representative speed-dependent error components shown in Fig. 18. (Representative position dependent error component)

[0040] The waveforms of the position-dependent error components over the entire stroke shown in Fig. 12 may be tabulated and stored in the memory 23, but as the amount of data will be large, a storage capacity for that amount must be secured in the memory 23. As shown in Fig. 12, the waveforms of the position-dependent error components pulsate periodically with the magnet pitch of the drive magnet 7, so the waveform of the representative position error component with respect to the magnet pitch of the drive magnet 7 is found as follows.

[0041] As shown in Fig. 19, a filter such as a moving average filter is applied to the waveform of the position-dependent error component to obtain a waveform of a smoothed position error undulation component. Next, the waveform of the smoothed position error undulation component is subtracted from the waveform of the original position-dependent error component to extract a pulsating component of the position-dependent error component as shown in Fig. 20. When the pulsating components of the position-dependent error component shown in Fig. 20 are averaged by the magnet pitch of 39 mm, a waveform with regularity as shown in Fig. 21 is obtained. In this embodiment, the waveform shown in Fig. 21 is used as the waveform of the representative position-dependent error component. Fig. 6 is a table of the waveform of the representative position-dependent error component shown in Fig. 21. Note that the waveform of the representative position-dependent error component shown in Fig. 21 is composed of two similar periods of waveforms, so the pitch between the north pole and south pole of the drive magnet 7 (19.5 mm) may be used as the magnet pitch. (Position information correction using representative position-dependent error components and velocity-dependent error components)

[0042] Figure 22 is a graph comparing the thrust generated in linear motor 1 when linear motor 1 is controlled using reference position information detected by reference measuring device 33 (reference scale), when linear motor 1 is controlled using uncorrected position information detected by encoder head 12 (before correction), and when linear motor 1 is controlled using position information in which the representative position-dependent error component and the velocity-dependent error component have been corrected (representative position-dependent error correction + velocity-dependent error correction).

[0043] As shown in FIG. 22, by correcting the position information using the representative position-dependent error component and the velocity-dependent error component and suppressing the periodic position error, it is possible to suppress thrust pulsation to the same extent as in the case where the linear motor 1 is controlled using position information in which the position-dependent error components and velocity-dependent error components shown in FIG. 16 have been corrected (position-dependent error correction + velocity-dependent error correction in FIG. 16). (effect)

[0044] The effects of the position information correction devices 21 and 41 of the linear motor 1 of this embodiment will be described below.

[0045] Using the position-dependent error components and speed-dependent error components stored in the memories 23 and 43, the position information of the linear motor 1 detected by the encoder head 12 can be effectively corrected.

[0046] The position-dependent error component can be obtained by using the difference between the position information detected by the encoder head 12 when the table 4 of the linear motor 1 is moved and the actual position information.

[0047] The speed-dependent error component can be obtained using the difference between the position information detected by the encoder head 12 when the table 4 of the linear motor 1 is moved at high speed and the position information detected by the encoder head 12 when the table 4 of the linear motor 1 is moved at low speed, and the speed difference between the high speed and low speed.

[0048] Since the driving magnet 7 of the linear motor 1 also serves as the scale of the encoder, costs can be reduced and position information of the table 4 can be detected even if the stroke of the table 4 is long.

[0049] Since the speed-dependent error components stored in the memories 23 and 43 are representative speed-dependent error components at positions within the magnet pitch of the drive magnet 7, the amount of data can be reduced.

[0050] Since the position-dependent error components stored in the memories 23 and 43 are representative position-dependent error components at positions within the magnet pitch of the drive magnet 7, the amount of data can be reduced.

[0051] Since the encoder head 12 includes the position information correction devices 21 and 41, the encoder head 12 can output corrected position information.

[0052] Since the driver 51 that controls the linear motor 1 includes at least the position-dependent error correction section and the speed-dependent error correction section of the position information correction device 41 , the driver 51 can correct the position information input from the encoder head 12 .

[0053] It should be noted that the present invention is not limited to the above-described embodiment, and can be embodied in other embodiments without departing from the spirit and scope of the present invention.

[0054] In the above embodiment, an example of a linear motor being a flat-type linear motor has been described, but the linear motor may also be a shaft-type linear motor including a shaft on which multiple rod-shaped magnets are arranged in series, and a mover having a coil surrounding the shaft.

[0055] In the above embodiment, the driving magnet of the linear motor also serves as the scale of the encoder, but these may be separated. [Explanation of symbols]

[0056] 1...Linear motor, 3...Mover, 7...Driving magnet, 12...Encoder head (position detector), 21...Position information correction device, 22a...Microcontroller (position-dependent error correction unit), 22b...Microcontroller (speed-dependent error correction unit), 23...Memory, 23a...Position-dependent error table, 23b...Speed-dependent error table, 31...Driver (control device), 33...Reference scale (reference measurement device), 41...Position information correction device, 42...Microcontroller (position-dependent error correction unit, speed-dependent error correction unit), 43...Memory, 51...Driver (control device), P...Position information

Claims

1. A position information correction device that corrects position information of a linear motor detected by a position detector, a memory for storing previously measured position-dependent error components and velocity-dependent error components; a position-dependent error correction unit that reads from the memory a position-dependent error component corresponding to the position information from the position detector and corrects the position information using the position-dependent error component; a speed-dependent error correction unit that reads from the memory a speed-dependent error component corresponding to the position information from the position detector and corrects the position information using the speed-dependent error component and speed information of the linear motor.

2. 2. The linear motor position information correction device according to claim 1, wherein the position-dependent error component is determined using a difference between the position information detected by the position detector when a mover of the linear motor is moved and the actual position information.

3. 3. The linear motor position information correction device according to claim 1, wherein the speed-dependent error component is determined using a difference between position information detected by the position detector when the movable element of the linear motor is moved at high speed and position information detected by the position detector when the movable element of the linear motor is moved at low speed, and a speed difference between the high speed and the low speed.

4. 3. The position information correction device for a linear motor according to claim 1, wherein a driving magnet for said linear motor also serves as a scale for said position detector.

5. 5. The position information correction device for a linear motor according to claim 4, wherein the speed-dependent error component stored in the memory is a representative speed-dependent error component at a position within a magnet pitch of the drive magnet.

6. 6. The position information correction device for a linear motor according to claim 4, wherein the position-dependent error component stored in the memory is a representative position-dependent error component at a position within a magnet pitch of the drive magnet.

7. 3. The position information correction device for a linear motor according to claim 1, wherein the position detector includes the position information correction device.

8. 3. The position information correction device for a linear motor according to claim 1, wherein a control device for controlling the linear motor includes at least the position-dependent error correction unit and the speed-dependent error correction unit of the position information correction device.

9. A position information correction method for correcting position information of a linear motor detected by a position detector, comprising the steps of: a step of reading a position-dependent error component corresponding to the position information detected by the position detector from position-dependent error components previously measured and stored in a memory, and correcting the position information using the position-dependent error component; a step of reading a speed-dependent error component corresponding to the position information detected by the position detector from speed-dependent error components measured in advance and stored in a memory, and correcting the position information using this speed-dependent error component and speed information of the linear motor.

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