Control device and transport system

Abstract

The control device (1) is configured to be applicable to a conveyance system (10) including a mover (4) moving along a conveyance path (8), a plurality of coil units (3) arranged along the conveyance path (8), a scale head (5) provided on the mover (4), a scale unit (6) arranged at predetermined intervals along the conveyance path (8) and detecting the position of the scale head (5), and a drive device (2) supplying a drive current to the coil unit (3). The control device (1) includes a mover position calculation unit (15) that calculates the mover position, which is position information of the mover (4), based on detection data of the scale unit (6), a mover speed calculation unit (121) that calculates the mover speed from the difference between a current calculation value and a previous calculation value for the mover position, and a mover speed correction unit (122) that corrects the mover speed in accordance with the mover position.

Description

[Technical field]

[0001] The present disclosure relates to a control device and a transport system that are applicable to a transport system that transports objects. [Background technology]

[0002] In production lines where factory automation is implemented, such as production lines for assembling industrial products or for packaging food, conveyor systems are commonly used to transport workpieces. In recent years, conveyor systems have been widely used in which the conveyor path for transporting the workpieces is divided into multiple zones, and carts carrying the workpieces are driven by control devices installed in each zone. This type of conveyor system is one of the conveyor systems that excels in terms of production efficiency.

[0003] As one form of conveying system, a so-called moving magnet type linear motor is utilized, in which a magnet and a scale head are arranged on a carriage as a movable element, and a coil unit and a scale unit are arranged on a stator of a conveying path. A moving magnet type linear motor is more suitable for long distance conveying than a moving coil type linear motor that uses a coil as a movable element. On the other hand, when a moving magnet type linear motor requires a long distance conveying compared to the size of the movable element, multiple coils according to the conveying distance are required. In addition, in a conveying system using a moving magnet type linear motor, it is desired that multiple carriages can be individually controlled, and that the movement of the carriages can be controlled with high precision even when multiple carriages are adjacent to each other.

[0004] In addition, the conveyor system has a configuration in which multiple stators are placed on the conveyor path, and a straight conveyor path and a curved conveyor path are combined to form a circular structure, causing multiple movers to make one revolution. In this configuration, the movers make one revolution while switching between conveyor paths of different shapes.

[0005] The following Patent Document 1 discloses a linear conveying system including a stator having multiple coils, multiple movers that move along the stator to convey a workpiece, a scale provided on the mover, and multiple sensors that detect the scale. The multiple movers have magnets, and the multiple sensors are arranged at predetermined intervals along the stator. The linear conveying system described in Patent Document 1 also includes a parameter recording unit and a position calculation unit. The parameter recording unit records a first cumulative value obtained by accumulating an error correction value for correcting an error between a set value of the predetermined interval and a measured value from an origin as a separate parameter for each sensor. The position calculation unit calculates the position of the mover based on the detection data of the sensor that detected the scale unit and the first cumulative value set in the sensor that detected the scale unit. Patent Document 1 describes that the mechanical coordinate position of the mover can be calculated using only the detection data of the sensor and the parameters set for the sensor, so that the mechanical coordinate position of the mover can be quickly calculated. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 7316554 Summary of the Invention [Problem to be solved by the invention]

[0007] In a transport system using a moving magnet type linear motor, the mover moves while switching between multiple coil units that are stators, and gaps of different lengths exist between the coil units. If gaps of different lengths exist between the coil units, then inevitably there will be gaps of different lengths between the scale units that detect the position of the scale head. For this reason, a transport system using a moving magnet type linear motor has the problem that an error occurs between the calculated mover speed and the actual mover speed depending on the variation in the gap length.

[0008] To address this problem, the technology of Patent Document 1 considers treating the gaps of different lengths between the coil units as an error and correcting the error under the assumption that gaps of different lengths exist between the coil units. Therefore, by using the technology of Patent Document 1, even if the mover changes coil units, it is possible to improve the calculation accuracy of the mover position and reduce the error between the mover speed calculated from the difference value of the mover position and the actual mover speed.

[0009] However, in the technology of Patent Document 1, in order to reduce the error between the mover speed calculated from the difference value of the mover position and the actual mover speed, it is necessary to accurately measure the length of the gap between each coil unit, which differs from one system to another. Therefore, the technology of Patent Document 1 has a problem that the number of steps required for adjustment work to build a system increases. In addition, the technology of Patent Document 1 has a problem that, among the errors between the mover speed calculated from the difference value of the mover position and the actual mover speed, the error generated by the mover trajectory being shifted from the scale unit cannot be corrected.

[0010] The present disclosure has been made in consideration of the above, and aims to provide a control device that can reduce the amount of labor required for adjustment work in system construction and can correct errors that occur when the trajectory of the movable element deviates from the scale unit. [Means for solving the problem]

[0011] In order to solve the above-mentioned problems and achieve the object, a control device according to the present disclosure is configured to be applicable to a transport system including at least one mover, a plurality of coil units, a scale head provided on the mover, a scale unit that detects the position of the scale head, and a drive device that supplies a drive current to the coil unit. The plurality of coil units are arranged along a transport path, the scale unit is arranged at a predetermined interval along the transport path, and the at least one mover moves along the transport path. The control device includes a mover position calculation unit, a mover speed calculation unit, and a mover speed correction unit. The mover position calculation unit calculates the mover position, which is position information of the mover, based on detection data of the scale unit that detects the position of the scale head. The mover speed calculation unit calculates the mover speed from a difference value between a current calculation value and a previous calculation value for the mover position. The mover speed correction unit corrects the mover speed according to the mover position. Effect of the Invention

[0012] The control device according to the present disclosure has the advantage that it is possible to reduce the man-hours required for adjustment work in system construction, and to correct errors that occur due to deviation of the trajectory of the mover from the scale unit. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram showing a configuration example of a transport system including a control device according to a first embodiment; [Diagram 2] FIG. 1 is a diagram showing an example of the configuration of a control device and a drive device according to a first embodiment; [Diagram 3] FIG. 10 is a diagram for explaining a method for calculating a mover position in the first embodiment; [Figure 4] FIG. 1 is a diagram showing a configuration example of a position and speed control unit according to a first embodiment; [Diagram 5] FIG. 1 is a first diagram illustrating an operation of a trajectory error correction unit according to the first embodiment; [Figure 6] FIG. 2 is a second diagram illustrating the operation of the trajectory error correction unit according to the first embodiment; [Figure 7]FIG. 13 is a diagram for explaining the effect of providing an internal mover speed switching unit in the mover speed correction unit according to the first embodiment. [Figure 8] FIG. 1 is a block diagram showing an example of a hardware configuration for implementing the functions of a control device and a drive device according to a first embodiment. [Figure 9] FIG. 11 is a block diagram showing another example of a hardware configuration for implementing the functions of the control device and the drive device according to the first embodiment. [Figure 10] FIG. 13 is a diagram showing an example of the configuration of a control device and a drive device according to a second embodiment; [Figure 11] FIG. 13 is a diagram showing a configuration example of a position and speed control unit according to a second embodiment; [Figure 12] FIG. 13 is a diagram illustrating the operation of a trajectory error correction unit according to the second embodiment; [Figure 13] FIG. 13 is a diagram for explaining a correction process performed in a trajectory error correction unit according to the second embodiment; [Figure 14] FIG. 13 is a diagram showing an example of a correction value table held in a trajectory error correction unit according to the second embodiment; [Figure 15] FIG. 11 is a diagram showing an example of a coefficient value table held in a trajectory error correction unit according to the second embodiment; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A control device and a transport system according to an embodiment of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0015] Embodiment 1 The transport system according to the first embodiment is a system used for transporting objects. The transport system transports objects by moving a mover on which the object is placed. An example of the mover is a dolly.

[0016] Fig. 1 is a diagram showing a configuration example of a transport system 10 including a control device 1 according to the first embodiment. As shown in Fig. 1, the transport system 10 according to the first embodiment includes a control device 1, driving devices 2A, 2B, 2C, 2D, 2E, 2F, 2G, and 2H (hereinafter, appropriately referred to as "2A to 2H", and the other symbols are similarly represented), coil units 3A to 3H, movers 4A to 4C, and scale heads 5A to 5C. Hereinafter, when the driving devices 2A to 2H are individually indicated without distinction, they will be collectively referred to as "driving device 2". The same applies to the coil units 3A to 3H, movers 4A to 4C, and scale heads 5A to 5C.

[0017] The conveying system 10 according to the first embodiment is a moving magnet type linear motor. A plurality of driving devices 2 are connected to each other. In the conveying system 10, a conveying path 8 along which the mover 4 moves is formed by connecting a plurality of driving devices 2 to each other. A plurality of coil units 3 are arranged along the conveying path 8, and the mover 4 moves along the conveying path 8. A guide rail (not shown in FIG. 1) is provided on the side of the conveying path 8. The mover 4 includes a permanent magnet and a guide roller (not shown in FIG. 1), and moves on the guide rail by the rotation of the guide roller. The mover 4 moves on the side of the conveying path 8 and stops on the side of the conveying path 8. The guide rail may be provided on the upper surface of the conveying path 8.

[0018] The driving device 2 supplies a driving current to the coil unit 3. When the driving current is supplied to the coil unit 3, a thrust is applied to the mover 4, and the mover 4 moves. The driving devices 2A, 2B, 2E, and 2F are configured as linear type driving devices 2 in which the conveying path 8 is a straight path, and the driving devices 2C, 2D, 2G, and 2H are configured as curved type driving devices 2 in which the conveying path 8 is a curved path.

[0019] 1 shows the conveying path 8 as a closed circular path, the shape of the path is arbitrary and is not limited to this example. The conveying path 8 of the conveying system 10 may be an open path. That is, the conveying path 8 of the conveying system 10 may be a path that has a start point and an end point. Furthermore, the conveying path 8 may not have a straight path, but may only have a curved path.

[0020] The direction of movement of each mover 4 is either clockwise in Fig. 1 or counterclockwise in Fig. 1. Of the directions of movement, the clockwise direction in Fig. 1 is referred to as the forward direction. Of the directions of movement, the counterclockwise direction in Fig. 1 is referred to as the reverse direction. Arrow 17A represents the forward direction, and arrow 17B represents the reverse direction.

[0021] 1, the conveying system 10 includes eight driving devices 2 and three movers 4. The number of driving devices 2 included in the conveying system 10 is arbitrary. That is, the number of driving devices 2 constituting the conveying path 8 is arbitrary, and the number of movers 4 moving on the conveying path 8 is also arbitrary. In addition, the number of movers 4 moving on the conveying path 8 may be one.

[0022] The control device 1 is connected to each of the driving devices 2 via a data communication line 7. The control device 1 controls each of the multiple driving devices 2. The data communication line 7 is composed of a communication line connecting the control device 1 to a driving device 2 that is one of the multiple driving devices 2, and a communication line connecting adjacent driving devices 2 to each other. That is, the conveyance system 10 is configured such that the control device 1 is connected to each of the driving devices 2 by a daisy chain connection. Note that the connection between the control device 1 and each of the driving devices 2 is not limited to a daisy chain connection. The connection between the control device 1 and each of the driving devices 2 may be a star connection in which each of the driving devices 2 is connected to the control device 1 via a communication hub. Alternatively, the conveyance system 10 may be configured to include multiple data communication lines 7, and the control device 1 and each of the driving devices 2 may be directly connected to each other by the data communication line 7. In addition, the data communication line 7 may not be a physical communication line, but may be a communication path capable of wireless communication.

[0023] Next, the configurations and functions of the control device 1 and the drive device 2 will be described with reference to Fig. 2. Fig. 2 is a diagram showing an example of the configuration of the control device 1 and the drive device 2 according to the first embodiment.

[0024] Fig. 2 shows a driving device 2A, a coil unit 3A which is a stator, a mover 4A, a scale head 5A provided on the mover 4A, and a scale unit 6A which detects the position of the scale head 5A. Fig. 2 also shows a driving device 2B, a coil unit 3B, a mover 4B, a scale head 5B provided on the mover 4B, and a scale unit 6B which detects the position of the scale head 5B. Fig. 2 also shows a control device 1. The scale units 6A and 6B are arranged at a predetermined interval along the transport path 8. Hereinafter, when the scale units 6A and 6B are referred to individually without distinction, they will be collectively referred to as "scale unit 6."

[0025] The driving device 2A includes a driving section 20A, a data communication section 21A, a detector communication section 24A, and a current detector 23A. The driving section 20A includes a plurality of current control sections 22A, and the coil unit 3A includes a plurality of coils 9A connected one-to-one to the current control sections 22A of the driving section 20A. Although the conveying path 8 is not shown in FIG. 2, the plurality of coils 9A are arranged along the conveying path 8. In addition, as shown in FIG. 2, the plurality of coils 9A are single-phase coils. The driving device 2B includes a driving section 20B, a data communication section 21B, and a detector communication section 24B, similar to the driving device 2A.

[0026] The mover 4A includes a permanent magnet 40. The permanent magnet 40 included in the mover 4A is a permanent magnet that contributes to driving the mover 4A.

[0027] As described with reference to Fig. 1, driving devices 2A, 2B, 2E, and 2F are all linear driving devices 2. In the linear driving device 2, the transport path 8 has a linear shape, and the scale unit 6 arranged along the transport path 8 also has a linear shape. On the other hand, driving devices 2C, 2D, 2G, and 2H are curved driving devices 2. In the curved driving device 2, the transport path 8 has a curved shape, and the scale unit 6 arranged along the transport path 8 also has a curved shape.

[0028] In FIG. 2, the five coils 9A in the coil unit 3A are labeled with reference numerals 9A1 to 9A5, the five current control units 22A in the driving unit 20A are labeled with reference numerals 22A1 to 22A5, and the current detectors 23A are labeled with reference numerals 23A1 to 23A5. Here, the five coils 9A labeled with reference numerals 9A1 to 9A5 are coils arranged in a range affected by the magnetic field generated by the permanent magnet 40 of the mover 4A, and contribute to driving the mover 4A. The five current control units 22A labeled with reference numerals 22A1 to 22A5 are current control units connected to the coils 9A labeled with reference numerals 9A1 to 9A5. The five current detectors 23A labeled with reference numerals 23A1 to 23A5 are current detectors that detect the currents flowing through the coils 9A1 to 9A5. Hereinafter, when the coils 9A1 to 9A5 are individually indicated without distinction, they will be collectively referred to as "coils 9A." Moreover, when current control units 22A1-22A5 are individually indicated without distinction, they are collectively referred to as "current control unit 22A." When current detectors 23A1-23A5 are individually indicated without distinction, they are collectively referred to as "current detector 23A."

[0029] When the positional relationship between the mover 4A and the coil unit 3A is as shown in FIG. 2, the coils 9A far from the mover 4A do not contribute much to driving the mover 4A. In the first embodiment, the coils 9A1 to 9A5 are described as the coils that contribute to driving the mover 4A. The coils 9A1 to 9A5 are supplied with driving currents by the current control units 22A1 to 22A5 that are connected one-to-one to the coils 9A1 to 9A5, respectively. The number of coils 9A that contribute to driving one mover 4 is determined by the number of coils 9A arranged in a range that is affected by the size of the permanent magnet 40 of the mover 4, the strength of the magnetic field, and the like. The number of coils 9A that drive one mover 4A described here is an example, and is not limited to this example. That is, the number of coils 9A that contribute to driving one mover 4A may be other than five.

[0030] The scale head 5 moves on the scale unit 6 together with the mover 4. The scale unit 6 detects the mover position, which is position information of the mover 4, and transmits it to the detector communication unit 24 of the drive device 2. Specifically, the scale unit 6A detects an intra-unit position yA representing the mover position in the coil unit 3A from the position of the scale head 5A provided on the mover 4A, and transmits the detected intra-unit position yA to the detector communication unit 24A. The scale unit 6B operates in a similar manner. The scale head 5 can be composed of, for example, a permanent magnet for position detection, and the scale unit 6 can be configured to include a sensor element that detects the magnetic field of the permanent magnet for position detection.

[0031] The control device 1 includes a mover position target value generating unit 11 , a position and speed control unit 12 , a current command generating unit 13 , a data communication unit 14 , and a mover position calculating unit 15 .

[0032] The data communication unit 14 and the data communication unit 21A are connected by a communication line 7A, and the data communication unit 21A and the data communication unit 21B are connected by a communication line 7B. This connection form is the daisy chain connection described above, and the communication data TxRx exchanged between the data communication unit 14 and the data communication unit 21A includes not only information on the drive unit 2A but also information on the drive units 2B to 2H. The data communication unit 21A of the drive unit 2A transmits the communication data TxRx received from the data communication unit 14 to the data communication unit 21B of the drive unit 2B. Similarly, the data communication unit 21B transmits the received communication data TxRx to the drive unit 2C, which is not shown in FIG. 2 below.

[0033] The data communication unit 14 receives information on the intra-unit position y via the data communication unit 21A of the driving device 2A. The intra-unit position y received by the data communication unit 14 includes not only the intra-unit position yA of the mover 4A, but also the intra-unit positions of the movers 4B and 4C.

[0034] The mover position target value generating unit 11 generates a mover position target value xref that indicates the position to which the mover 4 is to be moved, and outputs the mover position target value xref to the position and speed control unit 12. In this paper, any method may be used to generate the mover position target value xref. In FIG. 2, the mover position target value xref is configured to be generated inside the control device 1, but this is not limiting. The mover position target value xref may also be configured to be input to the control device 1 from outside. The mover position target value xref includes mover position target values ​​for all movers 4 present in the transport system 10.

[0035] The position and speed control unit 12 acquires the mover position target value xref of the mover 4 from the mover position target value generation unit 11, and acquires the mover position x from the mover position calculation unit 15. The position and speed control unit 12 generates a thrust command τref so that the mover position x follows the mover position target value xref, and outputs the thrust command τref to the current command generation unit 13. In this paper, any method may be used to generate the thrust command τref so that the mover position x follows the mover position target value xref. The thrust command τref is generated for each mover 4. Like the mover position target value xref, the thrust command τref includes thrust commands for all movers 4 present in the transportation system 10.

[0036] The current command generating unit 13 obtains a thrust command τref from the position and speed control unit 12, and obtains the mover position x from the mover position calculation unit 15. The current command generating unit 13 generates a current target value, which is a target value of a driving current to be passed through the multiple coil units 3, as a current command Iref so that the thrust generated in the mover 4 follows the thrust command τref. The current command Iref generated by the current command generating unit 13 includes a current command for the multiple coils 9A in all the coil units 3 present in the transportation system 10. Note that the current command Iref is not necessarily the same for all the coils 9A, and the current command Iref may be different for each coil 9A. The current command Iref generated by the current command generating unit 13 is output to the data communication unit 14. The data communication unit 14 obtains the current command Iref generated by the current command generating unit 13 and transmits it to the data communication unit 21A.

[0037] The mover position calculation unit 15 calculates the mover position x based on detection data from the scale unit 6 that detected the scale head 5 of the mover 4. Specifically, the mover position calculation unit 15 calculates the mover position x based on the intra-unit position y acquired from the data communication unit 14 and the distance to the scale origin, which is the reference position within the coil unit 3 of the scale unit 6, and outputs the mover position x to the position and speed control unit 12 and the current command generation unit 13. The method of calculating the mover position x in the mover position calculation unit 15 will be described later.

[0038] The data communication unit 21A of the drive device 2A receives the communication data TxRx transmitted from the data communication unit 14. The communication data TxRx transmitted from the data communication unit 14 includes not only the current command Iref for the drive device 2A but also the current commands Iref for the drive devices 2B-2H. The data communication unit 21A extracts current commands IrefA1-IrefA5, which are current commands for the drive device 2A, from the communication data TxRx, and outputs the extracted current commands IrefA1-IrefA5 to the current control units 22A1-22A5.

[0039] The current detectors 23A1-23A5 detect the currents IA1-IA5 flowing through the coils 9A1-9A5. The current control units 22A1-22A5 obtain the current commands IrefA1-IrefA5 from the data communication unit 21A, obtain the intra-unit position yA from the detector communication unit 24A, and obtain the detection values ​​of the currents IA1-IA5 from the current detectors 23A1-23A5. The current control units 22A1-22A5 control the currents IA1-IA5, which are the drive currents provided to the coils 9A1-9A5, so that the detection values ​​of the currents IA1-IA5 follow the current commands IrefA1-IrefA5. Any method may be used to control the currents IA1-IA5.

[0040] Fig. 3 is a diagram illustrating a method for calculating the mover position in embodiment 1. Fig. 3 shows coil units 3A and 3B, scale units 6A and 6B arranged at a predetermined interval along transport path 8, and mover 4A moving on scale units 6A and 6B along transport path 8.

[0041] 2 acquires the intra-unit position y, including the intra-unit position yA of the mover 4A, from the data communication unit 14. The mover position calculation unit 15 calculates the mover position xA using the distance to the scale origin of the scale unit 6B and the intra-unit position yA, according to the following equation (1).

[0042] Movable position xA = Distance to the scale origin of scale unit 6B + Radius correction value x unit position yA…(1)

[0043] In FIG. 3, the mover position xA is the distance to the mover 4A with the system origin as a reference, and the intra-unit position yA is the distance to the mover 4A with the scale origin of the scale unit 6B as a reference. Here, the system origin is the origin as seen from the entire transport system 10, and the scale origin is the origin as seen from each scale unit 6 or each coil unit 3. In FIG. 3, the left end position of the coil unit 3A is shown as the system origin, and the left end position of the coil unit 3B is shown as the scale origin of the scale unit 6B, but these examples are not limited to these. The system origin may be an arbitrarily selected reference position of the coil unit 3 or the scale unit 6. The scale origin may also be the center position or the right end position of the scale unit 6 or each coil unit 3.

[0044] In addition, in the above formula (1), the radius correction value is "1" when the mover 4A is on a straight path as shown in Fig. 3. In addition, when the mover 4A is on a curved path, the radius correction value is calculated by the following formula (2).

[0045] Radius correction value = radius of mover position xA / radius of unit position yA ... (2)

[0046] In the above formula (2), the "radius of the mover position xA" means the distance from the center of curvature of the curved path to the mover 4A, and the "radius of the in-unit position yA" means the distance from the center of curvature of the curved path to the scale head 5A. The radius of the mover position xA and the radius of the in-unit position yA are values ​​determined from the shape of the scale unit 6 or the guide rail at the position where the mover 4A is present. As the radius of the mover position xA, for example, the distance (radius of curvature) from the center of curvature of the curved path to the surface of the mover 4A can be used. As the radius of the in-unit position yA, for example, the radius of curvature of the guide rail can be used.

[0047] 3, when the scale origin of scale unit 6B is the left end of coil unit 3B, the distance to the scale origin of scale unit 6B relative to the system origin can be set to the width of coil unit 3A. Therefore, if information related to the width of coil unit 3A is set in advance in mover position calculation unit 15, it becomes possible to calculate the mover position xA relative to the system origin. Note that if there is a curved path between the system origin and scale unit 6B, or if scale unit 6B has a curved path, on these curved paths, the length along the inner circumference of the scale unit, or more precisely, the length of the arc at the mover surface radius, is treated as the distance.

[0048] Furthermore, even if the scale origin of scale unit 6B does not exist at the left or right end of coil unit 3B, if the distance from the left or right end of coil unit 3B to the scale origin of scale unit 6B is known, by setting this information in advance in mover position calculation unit 15, it becomes possible to calculate the mover position xA based on the system origin.

[0049] Note that Figure 3 explains how to calculate the mover position xA when the mover 4A is on the scale unit 6B, but it is possible to calculate the mover position xA in a similar manner even if the mover 4A is on any scale unit 6 other than the scale unit 6B.

[0050] Next, the configuration and operation of position and speed control unit 12 will be described. Fig. 4 is a diagram showing an example of the configuration of position and speed control unit 12 according to the first embodiment. As shown in Fig. 4, position and speed control unit 12 can be configured to include a mover speed calculation unit 121, a mover speed correction unit 122, and a thrust command calculation unit 123. Note that thrust command calculation unit 123 may be provided in current command generation unit 13. In this configuration, mover position target value xref is input to current command generation unit 13.

[0051] The mover speed calculation unit 121 acquires the mover position x from the mover position calculation unit 15. The mover speed calculation unit 121 calculates a pre-correction internal mover speed v'', using the following formula (3) based on the difference between the mover position x input this time and the mover position x input last time. The pre-correction internal mover speed v'', is a speed calculated inside the position and speed control unit 12, and is the speed before the correction process described later is performed.

[0052] Internal mover speed v'' before correction = (move element position x - previous move element position x) / one update period of move element position x ... (3)

[0053] In the above formula (3), one update period of the mover position x is one update period when performing update processing of the mover position x, that is, one period of the mover position calculation. Since the mover speed calculation unit 121 calculates the pre-correction internal mover speed v'' each time the mover position x is updated, one period of the mover speed calculation, which is one update period of the pre-correction internal mover speed v'', can be considered to be the same as one update period of the mover position x. Note that in this paper, with regard to the calculated value of the mover position x calculated by the mover position calculation unit 15 and input to the position and speed control unit 12, the calculated value of the mover position x input this time may be referred to as the "current calculated value", and the calculated value of the mover position x input previously may be referred to as the "previous calculated value".

[0054] The mover speed correction unit 122 obtains the pre-correction internal mover speed v'' from the mover speed calculation unit 121, and obtains the mover position x from the mover position calculation unit 15. The mover speed correction unit 122 corrects the pre-correction internal mover speed v'' in accordance with the mover position x, and outputs the corrected result as the internal mover speed v to the thrust command calculation unit 123. As shown in FIG. 4, the mover speed correction unit 122 can be configured to include a trajectory error correction unit 1221, a scale unit transfer determination unit 1222, an internal mover speed storage unit 1223, and an internal mover speed switching unit 1224.

[0055] The trajectory error correction unit 1221 acquires the pre-correction internal mover velocity v'' from the mover velocity calculation unit 121, and acquires the mover position x from the mover position calculation unit 15. The trajectory error correction unit 1221 corrects the pre-correction internal mover velocity v'' according to the mover position x, and outputs the corrected result as a current internal mover velocity v' to the internal mover velocity storage unit 1223 and the internal mover velocity switching unit 1224.

[0056] The operation of the trajectory error correction unit 1221 will be further described with reference to Fig. 5 and Fig. 6. Fig. 5 and Fig. 6 are first and second diagrams illustrating the operation of the trajectory error correction unit 1221 according to the first embodiment.

[0057] 5 shows how mover 4A transfers from linear scale unit 6B to curved scale unit 6C, which has a different shape. Note that the difference in length between the linear shape and the curved shape is not included in the "different shapes" mentioned here.

[0058] When the mover 4A passes between scale units 6 having different shapes, there is an area where the path of the scale head 5A provided on the mover 4A deviates from the scale unit 6B or the scale unit 6C. The scale unit 6B detects the linear position of the mover 4A as the intra-unit position xA. Therefore, when the path of the scale head 5A deviates from the scale unit 6B, the error between the pre-correction internal mover velocity v'' calculated using the mover position x including the intra-unit position xA detected by the scale unit 6B and the actual velocity of the mover 4A becomes large. In addition, the scale unit 6C detects the position of the mover 4A in the arc direction as the unit position xA. Therefore, when the path of the scale head 5A deviates from the scale unit 6C, the error between the pre-correction internal mover velocity v'' calculated using the mover position x including the intra-unit position xA detected by the scale unit 6C and the actual velocity of the mover 4A becomes large.

[0059] 6, like FIG. 5, shows the mover 4A transferring from the linear scale unit 6B to the curved scale unit 6C. As shown in FIG. 6, a linear guide rail 18B is arranged along the linear scale unit 6B, and a curved guide rail 18C is arranged along the curved scale unit 6C. A guide roller 19F at the front of the mover 4A in the moving direction is located on the scale unit 6C, and a guide roller 19R at the rear of the mover 4A in the moving direction is located on the scale unit 6B. The mover 4A transfers between scale units 6 of different shapes by moving from the linear guide rail 18B to the curved guide rail 18C by the rotation of the guide rollers 19F and 19R.

[0060] FIG. 6 is also a diagram showing the concept of a calculation model used to calculate a correction value for correcting the pre-correction internal mover velocity v''. In FIG. 6, the x and y coordinates of the guide roller 19R present on the scale unit 6B are expressed as (x R ,y R ), and the x and y coordinates of the guide roller 19F on the scale unit 6C are (x F ,y F ), and the x and y coordinates of the position of the mover 4A are (x C ,y C ), and the x and y coordinates of the detection position of the scale head 5A are (x S ,y S) The radius of curvature of the guide rail 18C is R, the distance between the guide rollers 19R and 19F is L, the distance from the position of the mover 4A to the detection position of the scale head 5A is D, the lead angle of the guide roller 19F is θ, and the inclination angle of the mover 4A is φ. The origin of these coordinates, that is, the coordinate origin of the calculation model, is a point moved from the point where the scale unit 6B is switched to the scale unit 6C toward the scale unit 6B by the distance L between the guide rollers 19R and 19F. The lead angle θ of the guide roller 19F is the angle formed by the line connecting the center of curvature and the gap between the scale units 6B and 6C and the line connecting the center of curvature and the guide roller 19F. The position of the mover 4A is assumed to be in the center between the guide rollers 19F and 19R, and the line connecting the detection position of the scale head 5A and the position of the mover 4A is assumed to be perpendicular to the line connecting the guide rollers 19F and 19R.

[0061] First, the x-y coordinates of the guide roller 19F (x F ,y F ) can be expressed by the following equations (4) and (5).

[0062] x F =Rsinθ+L…(4) y F = R-Rcosθ…(5)

[0063] Further, the lead angle θ of the guide roller 19F can be calculated by the following formulas (6) to (8).

[0064] a=sin -1 {(L 2 -R 2 -(Lx R ) 2 -(Ry R ) 2 ) / √((2(Lx R )×R) 2 +(2(Ry R )×R) 2 )}…(6) b=sin -1 {(-2×2(Ry R)×R) / √((2(L - x R )×R) 2 +(2(R - y R )×R) 2 )}…(7) θ = a - b …(8)

[0065] Also, the xy coordinates (x C , y C ) of the position of the mover 4A can be calculated by the following equations (9) and (10).

[0066] x C =(x F + x R ) / 2…(9) y C =(y F + y R ) / 2…(10)

[0067] Also, the xy coordinates (x S , y S ) of the detection position of the scale head 5A can be calculated by the following equations (11) and (12).

[0068] x S = x C + D×(y F - y R ) / L…(11) y S = y C + D×(x F - x R ) / L…(12)

[0069] Based on the above equations (4) to (12), the locus error correction unit 1221 calculates the xy coordinates (x C , y C ) of the position of the mover 4A and the xy coordinates (x S , y S) from these coordinates. The trajectory error correction unit 1221 also calculates the velocity of the mover 4A and the velocity of the scale head 5A from these coordinates, and calculates a correction value so that the velocity of the scale head 5A coincides with the velocity of the mover 4A. The trajectory error correction unit 1221 corrects the pre-correction internal mover velocity v'' using the calculated correction value to obtain a current internal mover velocity v', and outputs the obtained current internal mover velocity v' to the internal mover velocity storage unit 1223 and the internal mover velocity switching unit 1224.

[0070] The internal mover velocity storage unit 1223 stores the current internal mover velocity v' output from the trajectory error correction unit 1221 as data. In addition, the internal mover velocity storage unit 1223 stores data z -1 v′ is output to the internal mover speed switching unit 1224 .

[0071] The scale unit change determination unit 1222 detects from the value of the mover position x that the mover 4 has changed scale units 6, and outputs a scale unit change signal τs, which is a signal indicating the detection result, to the internal mover velocity switching unit 1224.

[0072] The internal mover speed switching unit 1224 acquires the current internal mover speed v′ from the trajectory error correction unit 1221 and the previous internal mover speed z from the internal mover speed storage unit 1223. -1 v' and obtains a scale unit change signal τs from the scale unit change determination unit 1222. The internal mover velocity switching unit 1224 determines whether or not the mover 4 has changed scale units 6 based on the scale unit change signal τs. When the mover 4 has changed scale units 6, the internal mover velocity switching unit 1224 changes the internal mover velocity z -1 If the mover 4 has not been transferred to the scale unit 6, the internal mover velocity switching unit 1224 outputs the current internal mover velocity v' as the internal mover velocity v.

[0073] The thrust command calculation unit 123 acquires the mover position target value xref from the mover position target value generation unit 11, acquires the mover position x from the mover position calculation unit 15, and acquires the internal mover velocity v from the internal mover velocity switching unit 1224. The thrust command calculation unit 123 calculates a thrust command τref so that the mover position x follows the mover position target value xref, and outputs the calculated thrust command τref to the current command generation unit 13.

[0074] As described above, when the mover 4A transfers between scale units 6, the mover speed correction unit 122 outputs to the thrust command calculation unit 123 the mover speed calculated one update cycle before.

[0075] FIG. 7 is a diagram for explaining the effect of providing the internal mover speed switching unit 1224 in the mover speed correction unit 122 according to the first embodiment.

[0076] In the transport system 10, it is ideal that the coil units 3 are configured without gaps as shown in FIG. 3. However, in the actual transport system 10, gaps exist between the coil units 3 as shown in FIG. 7. This gap differs not only between the coil units but also between individual systems, so it is difficult to set it before the system is shipped. Therefore, at the time of shipping the system, it is assumed that there are no gaps between the coil units 3. For this reason, the distance to the scale origin of the scale unit 6B is set to be the same as the width of the coil unit 3A. As a result, as shown in FIG. 7, an error occurs between the position indicating the distance to the scale origin of the scale unit 6B based on the system origin and the position indicating the scale origin of the scale unit 6B by the amount indicating the gap between the coil units 3.

[0077] As described above, the pre-correction internal mover velocity v'' calculated by the mover velocity calculation unit 121 is calculated by the following equation (3).

[0078] Internal mover speed v'' before correction = (mover position x - previous mover position x) / one update period of mover position x …(3) (Repost)

[0079] On the other hand, when mover 4A is transferred from scale unit 6A to scale unit 6B, a velocity error as shown in the following equation (13) will occur in the pre-correction internal mover velocity v″ calculated by equation (3) above.

[0080] Internal mover speed v'' before correction = (mover position x - previous mover position x) / one update period of mover position x ≒ Actual mover speed - (gap between coil units 3 / one update period of mover position x) …(13)

[0081] As shown in the above formula (13), a speed error corresponding to the error of the gap between the coil units 3 occurs in the pre-correction internal mover speed v'', relative to the actual mover speed.

[0082] As described above, when the thrust command calculation unit 123 calculates the thrust command τref, it uses the internal mover velocity v based on the pre-correction internal mover velocity v''. The phenomenon in which a velocity error occurs with respect to the actual mover velocity corresponding to the error in the gap between the coil units 3 only occurs when the mover 4A transfers between scale units 6. This phenomenon also occurs when transferring between scale units 6 having the same shape, as long as there is a gap between the coil units 3. If the velocity error that can be contained in the pre-correction internal mover velocity v'' is large, the error in the thrust command τref calculated using the internal mover velocity v based on the pre-correction internal mover velocity v'' will also be large. If the mover 4 is driven using a thrust command τref with a large error, there is a risk that shock or vibration will occur in the mover 4.

[0083] On the other hand, in the control device 1 according to the first embodiment, the internal mover speed switching unit 1224 is provided at the output stage of the mover speed correction unit 122. As described above, the internal mover speed switching unit 1224 changes the previous internal mover speed z -1v' is output as the internal mover velocity v. This makes it possible to prevent an error between the internal mover velocity v output from the mover velocity correction unit 122 to the thrust command calculation unit 123 and the actual mover velocity from becoming large, and also makes it possible to prevent a sudden change in the thrust command τref calculated by the thrust command calculation unit 123. As a result, it becomes possible to control the mover 4 so that no shock or vibration occurs in the mover 4.

[0084] As described above, the control device according to the first embodiment is configured to be applicable to a transport system including at least one mover, multiple coil units, a scale head provided on the mover, a scale unit that detects the position of the scale head, and a drive device that supplies a drive current to the coil unit. The multiple coil units are arranged along the transport path, the scale units are arranged at predetermined intervals along the transport path, and the at least one mover moves along the transport path. The control device includes a mover position calculation unit, a mover speed calculation unit, and a mover speed correction unit. The mover position calculation unit calculates the mover position, which is position information of the mover, based on detection data of the scale unit that detects the position of the scale head. The mover speed calculation unit calculates the mover speed from a difference value between a current calculation value and a previous calculation value for the mover position. The mover speed correction unit corrects the mover speed according to the mover position. According to the control device of the first embodiment, there is no need to measure the gaps between the coil units or the scale units as in Patent Document 1, so it is possible to reduce the number of steps required for adjustment work in building a system and correct errors caused by deviation of the trajectory of the mover from the scale unit. Also, since the control device of the first embodiment includes a mover speed correction unit that corrects the mover speed according to the mover position, it is possible to reduce the speed error between the mover speed and the actual mover speed, and it is possible to control the mover with high precision.

[0085] The control device according to the first embodiment may include a thrust command calculation unit that calculates a thrust command so that the mover position follows the mover position target value. Furthermore, the mover speed correction unit provided in the control device according to the first embodiment may include an internal mover speed switching unit that outputs the mover speed calculated one update cycle prior to the thrust command calculation unit when the mover switches scale units. Even when there is a gap between different coil units or scale units, the internal mover speed switching unit operates to suppress a speed error that may occur when the mover switches scale units, making it possible to control the mover so that no shock or vibration occurs to the mover.

[0086] Furthermore, the mover speed correction unit provided in the control device according to embodiment 1 may include a trajectory error correction unit that corrects the mover speed in accordance with the shapes of the scale unit in which the mover is present and the adjacent scale unit when the mover is transferred to a scale unit with a different shape. The trajectory error correction unit may be configured to correct the mover speed in accordance with the geometric trajectory of the mover calculated from the shapes of the scale unit in which the mover is present and the adjacent scale unit when the mover is transferred to a scale unit with a different shape. Since the trajectory error correction unit corrects the mover speed in accordance with the geometric trajectory of the mover, the speed error between the mover speed and the actual mover speed can be further reduced compared to a configuration without a trajectory error correction unit, making it possible to control the mover with higher precision.

[0087] The transport system according to the first embodiment includes at least one mover, a plurality of coil units, a scale head provided on the mover, a scale unit that detects the position of the scale head, and a drive device that supplies a drive current to the coil unit. The plurality of coil units are arranged along the transport path, the scale units are arranged at a predetermined interval along the transport path, and at least one mover moves along the transport path. A control device that controls the transport system includes a mover position calculation unit, a mover speed calculation unit, and a mover speed correction unit. The mover position calculation unit calculates the mover position, which is position information of the mover, based on detection data of the scale unit that detects the position of the scale head. The mover speed calculation unit calculates the mover speed from a difference value between a current calculation value and a previous calculation value regarding the mover position. The mover speed correction unit corrects the mover speed according to the mover position. According to the transport system according to the first embodiment, there is no need to measure the gap between the coil units or the scale units as in Patent Document 1, so that it is possible to reduce the number of steps required for adjustment work for system construction and to correct an error caused by the mover's trajectory being shifted from the scale unit. In addition, the control device provided in the conveying system according to embodiment 1 includes a mover speed correction unit that corrects the mover speed according to the mover position, so that the speed error between the mover speed and the actual mover speed can be reduced, making it possible to control the mover with high precision.

[0088] At the end of the first embodiment, the hardware configuration for realizing the functions of the control device 1 and the drive device 2 described above will be described with reference to Figs. 8 and 9. Fig. 8 is a block diagram showing an example of the hardware configuration for realizing the functions of the control device 1 and the drive device 2 according to the first embodiment. Fig. 9 is a block diagram showing another example of the hardware configuration for realizing the functions of the control device 1 and the drive device 2 according to the first embodiment.

[0089] When realizing some or all of the functions of the control device 1 and drive device 2 according to embodiment 1, the configuration can include a processor 300 that performs calculations, a memory unit 302 in which programs read by the processor 300 are stored, and a communication circuit 304 that transmits and receives signals, as shown in FIG. 8.

[0090] The processor 300 is an example of a computing means. The processor 300 may be a computing means called a microprocessor, a microcomputer, a CPU (Central Processing Unit), or a DSP (Digital Signal Processor). Examples of the storage unit 302 include non-volatile or volatile semiconductor memories such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable ROM), and EEPROM (registered trademark) (Electrically EPROM), magnetic disks, flexible disks, optical disks, compact disks, mini disks, and DVDs (Digital Versatile Discs).

[0091] The storage unit 302 stores a program for executing the functions of the control device 1 and the drive device 2 according to the first embodiment. The processor 300 receives and transmits necessary information via the communication circuit 304, executes the program stored in the storage unit 302, and refers to the table stored in the storage unit 302, thereby performing the above-mentioned processing. The calculation results by the processor 300 can be stored in the storage unit 302. Information regarding the width of the coil unit 3A described above can also be stored in the storage unit 302.

[0092] 9 may be used to realize some of the functions of the control device 1 and the drive device 2 according to the first embodiment. The processing circuit 303 may be a single circuit, a composite circuit, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination of these. Information input to the processing circuit 303 and information output from the processing circuit 303 may be transmitted and received via a communication circuit 304. Processing results by the processing circuit 303 may be stored in the storage unit 302.

[0093] Note that a part of the processing in the control device 1 and the drive device 2 may be performed by the processing circuit 303, and the processing that is not performed by the processing circuit 303 may be performed by the processor 300 and the storage unit 302.

[0094] Embodiment 2 In the second embodiment, a control device and a transport system that can solve the problem in the first embodiment and also solve another problem will be described.

[0095] Fig. 10 is a diagram showing an example of the configuration of a control device 1 and a driving device 2 according to embodiment 2. Compared with the control device 1 shown in Fig. 2, in Fig. 10, the position and speed control unit 12 is replaced with a position and speed control unit 12'. The roles of the mover position target value generation unit 11, the current command generation unit 13, the data communication unit 14 and the mover position calculation unit 15 are the same as those in embodiment 1 described above.

[0096] Fig. 11 is a diagram showing an example of the configuration of a position and velocity control unit 12' according to embodiment 2. Compared with the position and velocity control unit 12 shown in Fig. 4, in Fig. 11, the mover velocity correction unit 122 is replaced with a mover velocity correction unit 122', and the trajectory error correction unit 1221 is replaced with a trajectory error correction unit 1221'. In the position and velocity control unit 12', the roles of the mover velocity calculation unit 121 and the thrust command calculation unit 123 are the same as in the above-mentioned embodiment 1. Also, in the mover velocity correction unit 122', the roles of the scale unit transfer determination unit 1222, the internal mover velocity storage unit 1223, and the internal mover velocity switching unit 1224 are the same as in the above-mentioned embodiment 1.

[0097] In the case of the control device 1 according to the first embodiment, as shown in the above formulas (6) and (7), it is necessary to perform calculations with high calculation loads, such as the arcsine function and the square root, in real time. For this reason, the control device 1 according to the first embodiment needs to use high-performance and expensive processors 300 shown in Fig. 8 and processing circuit 303 shown in Fig. 9. In response to this problem, in the second embodiment, a control device 1 that can reduce the calculation load and use a cheaper processor 300 or processing circuit 303 will be described.

[0098] Figure 12 is a diagram illustrating the operation of a trajectory error correction unit 1221' according to embodiment 2. Like Figure 6, Figure 12 shows how mover 4A transfers from linear scale unit 6B to curved scale unit 6C. The symbols and terms in the figure are the same as those in Figure 6.

[0099] Various values ​​used in the above-mentioned formulas (4) to (12) are set values ​​that are determined according to the configuration of the transport system 10, and can be known in advance. For this reason, the trajectory error correction unit 1221' does not perform the calculations of formulas (4) to (12), but rather the correction values ​​obtained by performing the calculations of formulas (4) to (12) in advance are stored in the trajectory error correction unit 1221'.

[0100] FIG. 13 is a diagram for explaining the correction process performed by the trajectory error correction unit 1221′ according to the second embodiment. The horizontal axis of FIG. 13 indicates the mover position, and the vertical axis indicates the speed correction value. In FIG. 12, the mover position x at which the speed correction is required is from the position where the guide roller 19F of the mover 4A passes through the gap between the scale units 6B and 6C to the position where the guide roller 19R of the mover 4A passes through the gap between the scale units 6B and 6C. Therefore, as shown in FIG. 13, the correction value for correcting the pre-correction internal mover speed v″ is the position of the gap between the scale units 6B and 6C as the origin, and is in the range of ±L / 2 before and after the origin. Note that FIG. 13 shows the position of the mover 4A as being at the midpoint of the guide rollers 19F and 19R. When the position of the movable element 4A is not at the midpoint of the guide rollers 19F, 19R, the length between the start position and the end position of the correction remains the same at L, but it goes without saying that the length to the start position of the correction and the length to the end position of the correction based on the position of the gap between the scale units 6B, 6C are different.

[0101] FIG. 14 is a diagram showing an example of a correction value table held in the trajectory error correction unit 1221′ according to the second embodiment. FIG. 15 is a diagram showing an example of a coefficient value table held in the trajectory error correction unit 1221′ according to the second embodiment. The correction value table shown in FIG. 14 is a table showing a correspondence relationship between the mover position x and a correction value according to the mover position x. This correction value is a correction value calculated in advance based on the formulas (4) to (12). The trajectory error correction unit 1221′ does not calculate a correction value, but corrects the pre-correction internal mover velocity v″ by referring to the correction value table. If the correction value table does not contain a correction value corresponding to the input mover position x, an approximate value obtained by calculation processing by an interpolation process or an interpolation process may be used as the correction value, or a correction value corresponding to a mover position close to the input mover position x may be used to perform the correction process.

[0102] 15 is a table showing the correspondence between the degree and the coefficient value when calculating the correction value by performing n-th degree polynomial approximation. The trajectory error correction unit 1221' refers to the coefficient value table, applies the coefficient value to the n-th degree polynomial, calculates the correction value corresponding to the input mover position x, and corrects the pre-correction internal mover velocity v'' using the calculated correction value.

[0103] As described above, the mover speed correction unit provided in the control device according to the second embodiment stores in advance a correction value for correcting the internal mover speed, an approximation value that approximates the correction value, or a coefficient value for calculating the approximation value. The mover speed correction unit corrects the internal mover speed using the correction value, the approximation value, or the coefficient value. In the control device and transport system according to the second embodiment, the correction value for correcting the pre-correction internal mover speed can be found without performing calculation processing with a high load, so that the control device and transport system can be constructed more inexpensively while enjoying the effects of the first embodiment.

[0104] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies. Parts of the configurations may be omitted or modified without departing from the spirit of the invention. [Explanation of symbols]

[0105] 1 control device, 2, 2A to 2H drive device, 3, 3A to 3H coil unit, 4, 4A to 4C mover, 5, 5A to 5C scale head, 6, 6A to 6C scale unit, 7 data communication line, 7A, 7B communication line, 8 conveying path, 9A, 9A1 to 9A5 coil, 10 conveying system, 11 mover position target value generating unit, 12, 12' position speed control unit, 13 current command generating unit, 14, 21A, 21B data communication unit, 15 mover position calculation unit, 17A, 17B arrow, 18B, 18C guide rail, 19F, 19R guide roller, 20A, 20B drive unit, 22A, 22A1 to 22A5 current control unit, 23A, 23A1 to 23A5 current detector, 24, 24A, 24B detector communication unit, 40 Permanent magnet, 121 mover speed calculation unit, 122, 122' mover speed correction unit, 123 thrust command calculation unit, 300 processor, 302 memory unit, 303 processing circuit, 304 communication circuit, 1221, 1221' trajectory error correction unit, 1222 scale unit transfer determination unit, 1223 internal mover speed storage unit, 1224 internal mover speed switching unit.

Claims

1. A control device configured to be applicable to a transport system comprising: at least one movable element that moves along a transport path; a plurality of coil units arranged along the transport path; a scale head provided on the movable element; scale units arranged at predetermined intervals along the transport path for detecting the position of the scale head; and a drive device that supplies drive current to the coil units, wherein The control device is A movable element position calculation unit calculates the movable element position, which is the position information of the movable element, based on the detection data of the scale unit that has detected the position of the scale head, A movable element velocity calculation unit calculates the movable element velocity from the difference between the calculated value of the movable element position in the current calculation and the calculated value of the previous calculation, When switching between scale units, a movable element speed correction unit corrects the movable element speed so as to reduce the speed error between the movable element speed calculated by the movable element speed calculation unit and the actual movable element speed, A control device characterized by comprising:

2. The control device includes a thrust command calculation unit that calculates a thrust command so that the movable element position follows a target value for the movable element position. The movable element speed correction unit outputs the movable element speed calculated one update cycle prior to the thrust command calculation unit when the movable element switches to the scale unit. The aforementioned update cycle is one cycle of the movable element velocity calculation. The control device according to feature 1.

3. The movable element speed correction unit corrects the movable element speed when the movable element moves between scale units of different shapes, according to the shape of the scale unit in which the movable element resides and the adjacent scale unit. The control device according to claim 1 or 2.

4. The movable element speed correction unit corrects the movable element speed when the movable element moves between scale units of different shapes, according to the geometric trajectory of the movable element calculated from the shapes of the scale unit in which the movable element resides and the adjacent scale unit. The control device according to claim 3.

5. The movable element speed correction unit has a correction value for correcting the movable element speed, an approximate value obtained by approximating the correction value, or a coefficient value for calculating the approximate value stored in advance. The movable element speed correction unit corrects the movable element speed using the correction value, the approximate value, or the coefficient value. The control device according to feature 4.

6. A movable element that moves along a transport path, A plurality of coil units arranged along the aforementioned transport path, A scale head provided on the movable element, A scale unit is arranged at predetermined intervals along the transport path and detects the position of the scale head, A drive unit that supplies drive current to the coil unit, A movable element position calculation unit calculates the movable element position, which is the position information of the movable element, based on the detection data of the scale unit that has detected the position of the scale head, A movable element velocity calculation unit calculates the movable element velocity from the difference between the calculated value of the movable element position in the current calculation and the calculated value of the previous calculation, When switching between scale units, a movable element speed correction unit corrects the movable element speed according to the movable element position so as to reduce the speed error between the movable element speed calculated by the movable element speed calculation unit and the actual movable element speed, A transport system characterized by comprising the following features.

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