Transport System

Abstract

The transport system includes a plurality of transport path units (11) that constitute a transport path along which one or a plurality of transport bodies move. Each of the plurality of transport path units (11) includes a plurality of drive units that generate a thrust for moving the transport body by flowing an electric current, and a processor (27) that determines whether each of the plurality of drive units is in an overloaded state and determines whether the transport path unit (11) is in an overloaded state. In each of the plurality of transport path units (11), the processor (27) executes an overload protection process that reduces the temperature of a drive unit determined to be in an overloaded state or the temperature of the transport path unit (11) determined to be in an overloaded state.

Description

[Technical field]

[0001] The present disclosure relates to a transport system for transporting 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 generally 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 known as one of the conveyor systems with excellent production efficiency.

[0003] As one form of conveying system, a so-called moving magnet type linear motor is used, in which a magnet is arranged on the carriage, which is the moving element, and a coil is arranged on the stator that constitutes the conveying path. A moving magnet type linear motor is suitable for moving a moving element with a stroke that is longer than the length of the moving element. A number of coils are arranged on the conveying path in the direction in which the moving element is moved.

[0004] Patent Document 1 discloses a system that includes a carriage as a transport body and multiple coils arranged on a transport path, in which a magnetic field is generated by passing an electric current through each coil, and the carriage is moved by the action of the magnetic field. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 173607 / 1983 Summary of the Invention [Problem to be solved by the invention]

[0006] In a system such as that disclosed in Patent Document 1, overload protection is implemented to avoid problems such as burnout due to overheating when driving a linear motor. In a linear motor, the coil can be a heat source due to loss.

[0007] In a linear motor that moves a cart with a stroke longer than the length of the cart, if the rated current flows only through the coils in the portion where the cart is present among the multiple coils arranged on the conveying path, the cart can be moved without reducing the rated thrust. In a conveying system equipped with such a linear motor, it is rare that the operating pattern is such that the rated current always flows through all the coils arranged on the conveying path. In such a conveying system, if an overload protection function is installed to eliminate an overload state when the rated current always flows through all the multiple coils, the performance of the overload protection will exceed the performance that is appropriate for the operation of the conveying system. Excessive overload protection performance will make the configuration for overload protection unnecessarily large, which will be a factor in increasing the cost of the conveying system. For this reason, it has been desired that the conveying system be capable of overload protection that is appropriate for the operation of the conveying system.

[0008] The present disclosure has been made in consideration of the above, and has an object to provide a conveying system that enables overload protection appropriate for the operation of the conveying system. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems and achieve the object, the transport system according to the present disclosure includes a plurality of transport path units constituting a transport path along which one or a plurality of transport bodies move. Each of the plurality of transport path units has a plurality of drive units that generate a thrust for moving the transport body by flowing an electric current, and a processor that determines whether each of the plurality of drive units is in an overloaded state and determines whether the transport path unit is in an overloaded state. In each of the plurality of transport path units, the processor executes an overload protection process that reduces the temperature of the drive unit determined to be in an overloaded state or the temperature of the transport path unit determined to be in an overloaded state. Effect of the Invention

[0010] The conveying system according to the present disclosure has an effect of enabling overload protection suited to the operation of the conveying system. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing a configuration example of a transport system according to a first embodiment; [Diagram 2] FIG. 1 is a diagram showing a configuration example of a transport path unit provided in the transport system according to the first embodiment; [Diagram 3] FIG. 1 is a diagram for explaining thermal resistance of elements constituting a driving unit in a transport system according to a first embodiment; [Figure 4] FIG. 1 is a diagram showing an example of a first overload judgment curve that is a first criterion for judging an overload state in the transport system according to the first embodiment; [Diagram 5] FIG. 1 is a first diagram for explaining a worst-case loss of a transport path unit in a transport system according to a first embodiment; [Figure 6] FIG. 2 is a second diagram for explaining the worst loss of the transport path unit in the transport system according to the first embodiment; [Figure 7] FIG. 13 is a diagram showing an example of a second overload judgment curve that is a second criterion for judging an overload state in the transport system according to the first embodiment; [Figure 8]FIG. 1 is a first diagram for explaining a maximum rated loss of a transport path unit in a transport system according to a first embodiment; [Figure 9] FIG. 2 is a second diagram for explaining the maximum rated loss of the transport path unit in the transport system according to the first embodiment; [Figure 10] FIG. 13 is a diagram showing a configuration example of a controller provided in a transport system according to a fourth embodiment; [Figure 11] FIG. 13 is a diagram showing a configuration example of a learning device provided in a controller according to a fourth embodiment; [Figure 12] 13 is a flowchart showing a processing procedure of a learning device provided in a controller according to a fourth embodiment. [Figure 13] FIG. 13 is a diagram showing a configuration example of an operation command generator provided in a controller according to a fourth embodiment. [Figure 14] 11 is a flowchart showing the processing procedures of an operation command generator, a position command generator, and a coil drive command generator provided in the controller according to the fourth embodiment. [Figure 15] FIG. 1 shows an example of the configuration of a control circuit according to first to fourth embodiments. [Figure 16] FIG. 1 is a diagram showing an example of a configuration of a dedicated hardware circuit according to the first to fourth embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] A transport system according to an embodiment will be described in detail below with reference to the drawings.

[0013] Embodiment 1 1 is a diagram illustrating a configuration example of a conveyance system 1 according to a first embodiment. The conveyance system 1 is a system used for conveying objects. In the first embodiment, the conveyance system 1 conveys objects by moving a conveyance body on which the objects are placed.

[0014] The transport system 1 includes a plurality of transport path units 11A-11H, a controller 12, a direct current (DC) power source 13, and carriages 16A, 16B, and 16C. The controller 12 controls the operation of each of the carriages 16A, 16B, and 16C via the transport path units 11A-11H. In the following description, the transport path unit 11 refers to each of the transport path units 11A-11H without distinction.

[0015] The multiple transport path units 11 are connected to each other to form a transport path 10 along which the transport body moves. The multiple transport path units 11 move the transport body by applying power to the transport body. Each of the carriages 16A, 16B, and 16C is a transport body. In the following description, the carriage 16 refers to each of the carriages 16A, 16B, and 16C without distinction.

[0016] The conveying path 10 shown in Fig. 1 is circular. That is, the conveying path 10 shown in Fig. 1 is a closed path. The conveying path 10 of the conveying system 1 may be an open path. That is, the conveying path 10 of the conveying system 1 may be a path having a start point and an end point that are located apart from each other.

[0017] The transport path units 11A, 11B, 11E, and 11F are linear transport path units 11 that form a linear path. The transport path units 11C, 11D, 11G, and 11H are curved transport path units 11 that form a curved path, and change the traveling direction of the transport body. The transport path 10 may not have a transport path unit 11 that forms a linear path, and may be composed only of the transport path unit 11 that forms a curved path. The transport path 10 having a start point and an end point that are located at positions separated from each other may be composed only of the transport path unit 11 that forms a linear path. The overall shape of the transport path 10 is arbitrary.

[0018] The carriage 16 is attached to the side of the conveying path 10. The carriage 16 moves along a guide rail provided on the side of the conveying path 10. The carriage 16 moves on the side of the conveying path 10 and stops on the side of the conveying path 10. The conveying system 1 according to the first embodiment is a moving magnet type linear motor. The carriage 16 may move along a guide rail provided on the upper surface of the conveying path 10. The carriage 16 includes a permanent magnet constituting a mover, a permanent magnet for a linear scale, and a guide roller that moves on the guide rail by rotation. In FIG. 1, the guide rail, the guide roller, the permanent magnet constituting the mover, and the permanent magnet for the linear scale are not shown.

[0019] The traveling direction of each carriage 16 is a clockwise direction in Fig. 1 or a counterclockwise direction in Fig. 1. Of the traveling directions, the clockwise direction in Fig. 1 is the forward direction. Of the traveling directions, the counterclockwise direction in Fig. 1 is the reverse direction. Arrow 17A indicates the forward direction. Arrow 17B indicates the reverse direction.

[0020] In the example shown in FIG. 1, the conveying system 1 includes eight conveying path units 11 and three carts 16. The number of conveying path units 11 included in the conveying system 1 may be any number. That is, the number of conveying path units 11 constituting the conveying path 10 may be any number. The conveying system 1 may include a plurality of conveying path units 11. The number of carts 16 moving on the conveying path 10 may be any number. The conveying system 1 may include one or a plurality of carts 16.

[0021] The conveying system 1 is not limited to a system equipped with a linear motor, and may be a system equipped with a rotary motor. The conveying system 1 may be a belt conveyor equipped with a rotary motor and a belt rotated by the rotary motor. The belt conveyor moves workpieces placed on the belt. The conveying system 1 may be a roller conveyor equipped with a plurality of rollers and a rotary motor that rotates the rollers. The roller conveyor moves workpieces placed on the rollers.

[0022] The DC power supply 13 is connected to each transport path unit 11 via a DC power bus 15. The DC power supply 13 is a power supply device or a power supply circuit that outputs a direct current voltage. The DC power supply 13 supplies power to each transport path unit 11. Each transport path unit 11 shares the DC power supply 13.

[0023] A positive DC busbar and a negative DC busbar run through the DC power bus 15. The positive DC busbar is called a P busbar. The negative DC busbar is called an N busbar. The P busbar is connected to the positive pole of the DC power source 13. The N busbar is connected to the negative pole of the DC power source 13. Hereinafter, when referring to both the P busbar and the N busbar, they will be called a PN busbar. Each of the multiple transport path units 11 constituting the transport path 10 is connected to a common PN busbar.

[0024] The transport system 1 has a configuration in which each transport path unit 11 is connected to a DC power source 13 by a multi-drop connection. The connection between each transport path unit 11 and the DC power source 13 is not limited to a multi-drop connection, and may be a daisy chain connection. In the example shown in Fig. 1, the transport system 1 is provided with one DC power source 13, but the transport system 1 may be provided with multiple DC power sources 13. In other words, the transport system 1 may be configured with multiple power source domains.

[0025] The controller 12 is connected to each transport path unit 11 via a data communication line 14. The data communication line 14 is composed of a line connecting the transport path unit 11A, which is one of the multiple transport path units 11, to the controller 12, and a line connecting adjacent transport path units 11. The transport system 1 has a configuration in which each transport path unit 11 is connected to the controller 12 by a daisy chain connection.

[0026] The connection between each transport path unit 11 and the controller 12 is not limited to a daisy chain connection. The connection between each transport path unit 11 and the controller 12 may be a star connection in which each transport path unit 11 is connected to the controller 12 via a communication hub. Alternatively, the transport system 1 may include a plurality of data communication lines 14, and each transport path unit 11 and the controller 12 may be directly connected by the data communication lines 14.

[0027] The controller 12 generates an operation command indicating the manner of movement of each of the multiple carriages 16, and generates a position command for each carriage 16 based on the operation command. The operation command includes information such as acceleration, deceleration, and movement speed. The controller 12 generates a coil drive command based on the position command for each carriage 16. The controller 12 outputs a coil drive command to each transport path unit 11. The coil drive command includes a current command indicating a command value of a current to be passed through each coil of the transport path unit 11. Each transport path unit 11 controls the current flowing through each coil according to the current command included in the coil drive command. The controller 12 controls the movement of each carriage 16 by outputting a coil drive command to each transport path unit 11.

[0028] A control device higher than the controller 12, such as a programmable logic controller, may be connected to the controller 12. Such a control device outputs a command for sequence control to the controller 12. A human-machine interface may be connected to the controller 12. An operator operates the human-machine interface to input information to the human-machine interface. The human-machine interface also outputs information indicating the status of the conveyance system 1. The human-machine interface displays, for example, information indicating the status of the conveyance system 1. The controller 12 may obtain operation information of the cart 16 from the higher-level control device or human-machine interface, and generate a position command based on the operation information. The operation information is information indicating a schedule for the movement of each of the multiple carts 16 on the conveyance path 10. The operation information includes information on the movement start position, the stop position, the movement time, and the like.

[0029] Next, the configuration of the transport path unit 11 will be described. Here, the configuration of the transport path unit 11 will be described using a straight-line type transport path unit 11 as an example. In the curved-line type transport path unit 11, the coil arrangement is different from that in the straight-line type transport path unit 11. The configuration of the curved-line type transport path unit 11 is similar to the configuration of the straight-line type transport path unit 11, except for the difference in the coil arrangement.

[0030] Fig. 2 is a diagram showing a configuration example of the transport path unit 11 provided in the transport system 1 according to the embodiment 1. Fig. 2 shows a schematic configuration of the transport path unit 11 and a schematic configuration of the carriage 16 present on the transport path unit 11. The carriage 16 has a permanent magnet 40 forming a mover and a permanent magnet 41 for a linear scale.

[0031] 2 shows one N-pole magnet and one S-pole magnet as the permanent magnet 40 constituting the mover, but the permanent magnet 40 constituting the mover may have any number of N-pole magnets and any number of S-pole magnets. In the permanent magnet 40, the N-pole magnets and the S-pole magnets are arranged alternately along the direction in which a plurality of coils 20, which will be described later, are arranged. The cart 16 moves by obtaining a driving force due to the interaction between an electromagnetic force generated by the coils 20, which will be described later, possessed by the transport path unit 11 and a magnetic field generated by the permanent magnet 40 constituting the mover.

[0032] 2 shows four N-pole magnets and four S-pole magnets as the permanent magnet 41 for the linear scale. As shown in Fig. 2, in the permanent magnet 41, the N-pole magnets and the S-pole magnets are arranged alternately along the direction in which a plurality of coils 20, which will be described later, are arranged. The permanent magnet 41 for the linear scale can have any number of N-pole magnets and any number of S-pole magnets.

[0033] The transport path unit 11 includes a plurality of coils 20. In the example shown in FIG. 2, the transport path unit 11 includes 12 coils 20. The number of coils 20 included in the transport path unit 11 is arbitrary. In a linear transport path unit 11, the plurality of coils 20 are arranged along a linear path. In a curved transport path unit 11, the plurality of coils 20 are arranged along a curved path. Each coil 20 of the transport path unit 11 includes not only a pure inductance component but also a coil resistance.

[0034] An inverter 21 is connected to each coil 20 of the transport path unit 11. The inverter 21 includes a switching element, and supplies the coil 20 with power that has been converted by switching of the switching element. The switching element is not shown. The inverter 21 controls the current flowing through the coil 20. The inverter 21 is a single-phase full-bridge inverter circuit or a single-phase half-bridge inverter circuit. The inverter 21 may be a three-phase inverter circuit connected to three coils 20.

[0035] Each inverter 21 of the transport path unit 11 is connected between a P bus 31, which is the positive wiring of the DC power supply bus 15, and an N bus 32, which is the negative wiring of the DC power supply bus 15. Each inverter 21 converts DC power from the PN bus into AC power and supplies the AC power to the coil 20. The inverter 21 performs power conversion from DC power to AC power by switching a switching element.

[0036] The coil 20 generates electromagnetic force, which is a thrust force for moving the cart 16, by power supply from the inverter 21. The coil 20 and the inverter 21 function as a drive unit that generates the thrust force for moving the cart 16 by the flow of current. The transport path unit 11 includes a plurality of drive units.

[0037] A current sensor 22 is connected to each coil 20 of the transport path unit 11. The current sensor 22 detects an actual coil current value, which is the current value of the current flowing through the coil 20. In addition, a capacitor 23, which is an electrolytic capacitor, is connected between the P bus 31 and the N bus 32 in the transport path unit 11. By providing the capacitor 23, a sudden voltage fluctuation in the PN bus is prevented in the transport path unit 11. A voltage detector 33 is connected between the P bus 31 and the N bus 32. The voltage detector 33 detects a bus voltage, which is a voltage between the P bus 31 and the N bus 32, with the potential of the N bus 32 as a reference. The voltage detector 33 outputs the detection result of the bus voltage to the processor 27.

[0038] A current controller 24 for controlling the inverter 21 is connected to each inverter 21 of the conveying path unit 11. The current controller 24 calculates a voltage value of a voltage to be applied to the coil 20 based on a command value of a current to be passed through the coil 20 and an actual coil current value detected by a current sensor 22. The current controller 24 transmits a pulse width modulation (PWM) signal obtained by comparing the calculated voltage value with a triangular wave to the inverter 21. The current controller 24 transmits a PWM signal to the inverter 21 to cause the inverter 21 to perform switching. As a result, the current controller 24 applies a voltage to the coil 20 for passing a current of a desired current value through the coil 20. The current controller 24 may calculate a voltage value of a voltage to be applied to the coil 20 by performing a proportional integral differential (PID) control of the voltage to be applied to the coil 20 based on a deviation between a current command value and an actual coil current value. In addition, the current controller 24 outputs the actual coil current value detected by the current sensor 22 to the processor 27 .

[0039] The transport path unit 11 includes a linear scale 25, a processor 27, and a communication slave station 28. The linear scale 25 is a detection unit that detects the position of the cart 16 on the transport path unit 11. The linear scale 25 is provided on the transport path 10 when a plurality of transport path units 11 are connected to each other to form the transport path 10. The processor 27 is a CPU (Central Processing Unit). The processor 27 may be an arithmetic device, a processing device, a microprocessor, a microcomputer, or a DSP (Digital Signal Processor).

[0040] The linear scale 25 includes a plurality of position sensors 26. Each position sensor 26 is a sensor that detects a magnetic field, such as a Hall sensor or a magnetic resistance sensor. Each position sensor 26 detects the magnetic field of the permanent magnet 40 or the magnetic field of the permanent magnet 41. Here, the position sensor 26 is a Hall sensor equipped with two Hall elements. The distance between the two Hall elements is equivalent to half the magnetic pole pitch of the permanent magnet 41. Each Hall element converts the magnetic field into an electric signal and outputs the electric signal. The electric signal output by each Hall element changes with the movement of the cart 16. The waveform of the electric signal output by one Hall element in the position sensor 26 is a sine wave. The waveform of the electric signal output by the other Hall element in the position sensor 26 is a cosine wave.

[0041] An electric signal from each position sensor 26 of the linear scale 25 is input to the processor 27. An AD (Analog to Digital) converter provided with the processor 27 detects sine waves and cosine waves. The processor 27 detects the position of the cart 16 with respect to the position sensor 26 by calculating the arctan based on the sine wave information and the cosine wave information. In this way, the processor 27 obtains position sensor information that indicates the relative position of the cart 16 with respect to the position sensor 26. Note that communication lines between each position sensor 26 and the processor 27 are omitted in FIG. 2.

[0042] The processor 27 acquires a voltage value, which is a detection result of the bus voltage, from the voltage detector 33. The processor 27 acquires an actual coil current value from the current controller 24. When determining whether or not an overload state exists, the processor 27 performs a calculation that incorporates the actual coil current value. The determination of whether or not an overload state exists will be described later.

[0043] The communication slave station 28 is a communication slave station on the transport path unit 11 side. The data communication line 14 is connected to the communication slave station 28. When each transport path unit 11 and the controller 12 are connected by a daisy chain connection, the communication slave station 28 is configured to be able to connect two lines constituting the data communication line 14. The communication slave station 28 receives a coil drive command transmitted from the controller 12. The communication slave station 28 transmits a current command included in the coil drive command to each of the multiple current controllers 24. As a result, the transport path unit 11 controls the current flowing through each of the multiple coils 20 in accordance with the coil drive command.

[0044] Furthermore, communication slave station 28 acquires position sensor information from processor 27. Communication slave station 28 transmits the acquired position sensor information to controller 12. Communication slave station 28 performs, for example, fixed-period communication in which it receives coil drive commands and transmits position sensor information at a fixed period. Instead of such fixed-period communication, communication slave station 28 may receive coil drive commands and transmit position sensor information non-periodically.

[0045] The transport path unit 11 includes a temperature sensor . The temperature sensor measures the temperature of the transport path unit 11. The temperature sensor outputs the temperature measurement result to the processor 27. The processor 27 monitors the temperature measured by the temperature sensor .

[0046] As described above, the transport path unit 11 mainly has a function of controlling the energization of the coil 20 and a function of acquiring position sensor information. Each of the multiple transport path units 11 constituting the transport path 10 similarly controls the energization of the coil 20 and similarly acquires position sensor information.

[0047] Next, overload protection in the transport path unit 11 will be described. In each of the multiple transport path units 11 provided in the transport system 1, the processor 27 determines whether each of the multiple driving units is in an overloaded state, and determines whether the transport path unit 11 is in an overloaded state. In each of the multiple transport path units 11 provided in the transport system 1, the processor 27 executes an overload protection process to reduce the temperature of the driving unit determined to be in an overloaded state or the temperature of the transport path unit 11 determined to be in an overloaded state.

[0048] The overloaded state of the drive unit means that the elements constituting the drive unit are in an overheated state. In other words, the overloaded state of the drive unit means that the temperature of the elements constituting the drive unit exceeds the temperature at which the elements can continue to operate normally. The overloaded state of the transport path unit 11 means that the entire inside of the transport path unit 11 is in an overheated state. In other words, the overloaded state of the transport path unit 11 means that the temperature inside the transport path unit 11 exceeds the temperature at which each of the elements provided inside the transport path unit 11 can continue to operate normally. The elements provided inside the transport path unit 11 include elements constituting the drive unit and elements other than the elements constituting the drive unit. The elements other than the elements constituting the drive unit are, for example, the capacitor 23 or the processor 27.

[0049] Here, overload protection of the drive unit will be described. Processor 27 monitors whether or not one or more elements included in the drive unit are in an overload state. That is, the drive unit includes elements to be monitored for whether or not they are in an overload state. Here, inverter 21, which is a first element included in the drive unit, and coil 20, which is a second element included in the drive unit, are assumed to be the elements to be monitored.

[0050] Each of the coil 20 and the inverter 21 has an electrical resistance component. The coil 20 generates a loss according to the current value of the current flowing through the coil 20. The inverter 21 generates a loss according to the current value of the current flowing through the inverter 21. In the coil 20, the coil resistance is a cause of the loss.

[0051] The inverter 21 includes semiconductor switching elements such as MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) or IGBTs (Insulated Gate Bipolar Transistors) and commutation diodes. In the inverter 21, losses may occur due to resistance when the MOSFETs or IGBTs are energized, or forward losses in the diodes.

[0052] In elements such as the coil 20 or the inverter 21, heat is generated due to loss, and when the temperature of these elements exceeds the allowable temperature of the elements, deterioration or destruction of the elements may occur. The deterioration or destruction of the elements mentioned here includes, for example, a decrease in the electromagnetic force generated by the coil 20, damage due to burning of the coil 20, adhesion or destruction of the switching element in the inverter 21, or destruction of the diode in the inverter 21. For this reason, in the transport path unit 11, overload protection is performed for the coil 20 and the inverter 21, which are elements that constitute the drive unit.

[0053] If the steady temperature rise of the elements that make up the drive unit is ΔT [K], ΔT is expressed by the following formula (1): R th [K / W] is the thermal resistance of the element and represents the thermal resistance in steady state. P[W] represents the loss. ΔT=R th ×P ···(1)

[0054] The loss P is expressed by the following formula (2): R [Ω] represents the resistance of the element. I [Arms] represents the effective value of the current flowing through the element. P = R × I 2 (2)

[0055] Processor 27 acquires the actual coil current value from current controller 24. Processor 27 calculates the effective value of the current flowing through the elements constituting the drive unit based on the actual coil current value. The current value at which the element's temperature becomes the allowable temperature of the element as a result of current flowing through the element is set to the maximum rated current value. If the effective value of the current flowing through the element constituting the drive unit is equal to or less than the maximum rated current value of the element, it is possible to continuously flow current through the element.

[0056] The thermal resistance of the elements that make up the drive unit also includes thermal resistance due to transient losses. Thermal resistance due to transient losses is called transient thermal resistance. Even if a current that exceeds the maximum rated current value of an element flows through that element, the element will not be destroyed if the element temperature falls below the allowable temperature because the current flows for a short period of time.

[0057] FIG. 3 is a diagram for explaining the thermal resistance of the elements constituting the driving unit in the transport system 1 according to the first embodiment. FIG. 3 shows a graph showing the relationship between the transient thermal resistance and time. The vertical axis shown in FIG. 3 is the transient thermal resistance θ th The vertical axis in Fig. 3 represents time [s]. The vertical axis in Fig. 3 and the horizontal axis in Fig. 3 are both on a logarithmic scale.

[0058] As shown in Figure 3, the transient thermal resistance increases as time increases, and becomes constant when the time exceeds a certain time. The value of the transient thermal resistance when it becomes constant is R, which is the thermal resistance in the steady state. th Matches the value of

[0059] FIG. 4 is a diagram showing an example of a first overload judgment curve that is a first judgment criterion for an overload state in the transportation system 1 according to the first embodiment. The first overload judgment curve that is the first judgment criterion represents the relationship between a first load judgment value and time. The first load judgment value is a threshold value of a current flowing through an element when the element is not in an overload state and when the element is in an overload state. The vertical axis shown in FIG. 4 represents time [s]. The horizontal axis shown in FIG. 4 represents a current effective value that is an effective value of a current flowing through an element. It can also be said that the horizontal axis shown in FIG. 4 represents the amount of load applied to an element.

[0060] The processor 27 uses the first criterion, which is the relationship between the first load judgment value and the time during which a current flows through the element, i.e., a preset first overload judgment curve, to compare the effective value of the current flowing through the element constituting the drive unit and the time during which a current flows through the element constituting the drive unit with the first overload judgment curve to judge whether the element is in an overload state. That is, the processor 27 judges whether the element constituting the drive unit is in an overload state by comparing the first criterion with the effective value of the current flowing through the element constituting the drive unit and the time during which a current flows through the element. The first overload judgment curve, which is the first criterion, may be preset in the processor 27, or the processor 27 may read out the first overload judgment curve that is preset by recording it on a recording medium, and use the first overload judgment curve for the operation of the processor 27.

[0061] A curve 51 shown in FIG. 4 is an example of a first overload judgment curve for the coil 20. A curve 52 shown in FIG. 4 is an example of a first overload judgment curve for the inverter 21. In the curve 51, the effective current value, which is the first load judgment value, decreases as time increases and becomes constant when the time exceeds a certain time. In the curve 51, the effective current value I1 when the effective current value becomes constant is the maximum rated current value of the coil 20. In the curve 52, the effective current value, which is the first load judgment value, decreases as time increases and becomes constant when the time exceeds a certain time. In the curve 52, the effective current value I2 when the effective current value becomes constant is the maximum rated current value of the inverter 21.

[0062] Points 53, 54, and 55 each represent a current conduction pattern that is a combination of the time during which current flows through the coil 20 and the inverter 21 and the effective value of the current flowing through the coil 20 and the inverter 21. In the case of the first current conduction pattern represented by point 53, the effective value of the current flowing through the coil 20 and the inverter 21, which are elements constituting the drive unit, is smaller than the maximum rated current value of the coil 20 and is smaller than the maximum rated current value of the inverter 21. Therefore, if the effective current value of the first current conduction pattern is used, even if current flows continuously through the coil 20 and the inverter 21, neither the coil 20 nor the inverter 21 will be in an overload state. Therefore, the processor 27 determines that, for the first current conduction pattern, neither the coil 20 nor the inverter 21 is in an overload state. In other words, the processor 27 determines that the drive unit is not in an overload state.

[0063] In the case of the second energization pattern represented by point 54, the effective value of the current flowing through the coil 20 and the inverter 21, which are elements constituting the drive unit, is greater than the maximum rated current value of the coil 20 and greater than the maximum rated current value of the inverter 21. However, the effective value of the current flowing through the coil 20 and the inverter 21 is smaller than the first load judgment value represented by the curve 51 and smaller than the first load judgment value represented by the curve 52. In the case of the second energization pattern, the energization is transient and short-term, and neither the coil 20 nor the inverter 21 is in an overload state. Therefore, the processor 27 determines that neither the coil 20 nor the inverter 21 is in an overload state for the second energization pattern. In other words, the processor 27 determines that the drive unit is not in an overload state.

[0064] In the case of the third energization pattern represented by point 55, the effective value of the current flowing through the coil 20 and the inverter 21, which are elements constituting the drive unit, is greater than the maximum rated current value of the coil 20 and less than the maximum rated current value of the inverter 21. The effective current value of the current flowing through the coil 20 and the inverter 21 is greater than the first load judgment value represented by curve 51. In the case of the third energization pattern, the energization is not transient but is long-term, and the inverter 21 does not enter an overload state, but the coil 20 does enter an overload state. Therefore, for the third energization pattern, the processor 27 judges that the inverter 21 is not in an overload state, but the coil 20 is in an overload state. Since the coil 20 is in an overload state, the processor 27 judges that the drive unit is in an overload state.

[0065] In this way, the processor 27 judges whether or not the drive unit is in an overload state based on the effective value of the current flowing through the element and the time during which the current flows through the element. In the above description, the coil 20 and the inverter 21 are the monitored objects in the drive unit, but the monitored object may be either the coil 20 or the inverter 21. Also, the monitored objects may include elements other than the coil 20 and the inverter 21. The monitored object may be any element through which a current flows. The processor 27 judges whether or not the drive unit is in an overload state using an overload judgment curve that matches the elements that constitute the drive unit to be monitored.

[0066] Next, the determination of whether or not the drive unit is in an overload state will be described in more detail. When the processor 27 acquires the actual coil current value from the current controller 24, it performs a first-order lag filter process on the actual coil current value. The processor 27 compares the current conduction pattern, which is a combination of the actual coil current value after the first-order lag filter process and the time during which current flows through the coil 20 and the inverter 21, with a first overload determination curve to determine whether or not each of the coil 20 and the inverter 21 is in an overload state. The processor 27 has a function of determining whether or not the coil 20 and the inverter 21 provided in each of the multiple drive units provided in the transport path unit 11 are in an overload state in this manner.

[0067] Next, a specific example of the overload protection process when the drive unit is determined to be in an overloaded state will be described. When at least one of the coil 20 and the inverter 21 is determined to be in an overloaded state in the drive unit, the processor 27 transmits an alarm indicating the overloaded state to each transport path unit 11 of the transport system 1.

[0068] The processor 27 of each transport path unit 11 executes overload protection processing when the transport path unit 11 receives an alarm. In this example, when the processor 27 of each transport path unit 11 receives an alarm, the processor 27 stops the current supply to each drive unit by the current controller 24 as overload protection processing. In this way, the processor 27 of each transport path unit 11 controls to stop all the carriages 16 present in the transport system 1. In this example, when it is determined that at least one of the multiple drive units in one of the multiple transport path units 11 is in an overload state, the multiple transport path units 11 stop all the carriages 16 present on the transport path 10 by overload protection processing. The overload protection processing in this case is a process of lowering the temperature of the drive unit by making the load of the coil 20 and the load of the inverter 21 zero.

[0069] Each transport path unit 11 may decelerate each cart 16 and then stop it by the overload protection process. Each transport path unit 11 may activate regenerative braking by shorting the coil 20 by the overload protection process. The processor 27 of each transport path unit 11 may also reduce the amount of current flowing to each drive unit as the overload protection process. In this case, the processor 27 of each transport path unit 11 decelerates all the carts 16 present in the transport system 1 by controlling to reduce the amount of current. The overload protection process in this case is a process of lowering the temperature of the drive unit by lowering the load on the coil 20 and the load on the inverter 21.

[0070] In this way, when at least one of the plurality of drive units in one of the plurality of transport path units 11 is determined to be in an overload state, the plurality of transport path units 11 may decelerate all of the carts 16 present on the transport path 10 by overload protection processing. The transport system 1 can avoid problems such as burnout due to overheating by stopping or decelerating all of the carts 16 present on the transport path 10 by overload protection processing.

[0071] In the above description, all the dollies 16 present on the conveying path 10 are stopped or decelerated by the overload protection process, but the overload protection process executed by the conveying system 1 is not limited to this. When at least one of the multiple driving units in one of the multiple conveying path units 11 is determined to be in an overloaded state, only the conveying path unit 11 including the driving unit determined to be in an overloaded state may stop or decelerate the dolly 16 by the overload protection process. In this case, the dolly 16 present on the conveying path 10 composed of the conveying path units 11 other than the conveying path unit 11 including the driving unit determined to be in an overloaded state is not stopped or decelerated. Then, when only the conveying path unit 11 including the driving unit determined to be in an overloaded state stops or decelerates the dolly 16 by the overload protection process, all the dollies 16 present on the conveying path unit 11 including the driving unit determined to be in an overloaded state may be stopped or decelerated, or some of the dollies 16 present on the conveying path unit 11 including the driving unit determined to be in an overloaded state may be stopped or decelerated. In this case, the processor 27 stops the power supply to each drive unit or reduces the amount of current flowing to each drive unit only in the transport path unit 11 including the drive unit determined to be in an overloaded state. In this case, the transport system 1 can also avoid problems such as burnout due to overheating.

[0072] Alternatively, the overload protection process when at least one of the multiple drive units in one of the multiple transport path units 11 is determined to be in an overloaded state may be to stop power supply only to the drive unit determined to be in an overloaded state. In this case, the transport system 1 can also avoid problems such as burnout due to overheating.

[0073] Next, a description will be given of a determination as to whether the transport path unit 11 is in an overloaded state, and a specific example of an overload protection function when the transport path unit 11 is determined to be in an overloaded state. In each of the multiple transport path units 11 provided in the transport system 1, the processor 27 determines whether the transport path unit 11 is in an overloaded state. In each of the multiple transport path units 11, the processor 27 executes an overload protection process to lower the temperature of the transport path unit 11 determined to be in an overloaded state.

[0074] In addition to the coil 20 and inverter 21, which are elements constituting the drive unit, electronic components such as a capacitor 23 and a processor 27 are provided inside the housing of the transport path unit 11. In general, the allowable temperature of the capacitor 23 and the allowable temperature of the processor 27 are lower than the allowable temperature of the coil 20 or the allowable temperature of the inverter 21.

[0075] Here, the loss in the case where the current value flowing through all the coils 20 of the transport path unit 11 is the maximum rated current value of the coils 20 is defined as the worst loss of the transport path unit 11. In the case where the transport path unit 11 is provided with 12 coils 20 as shown in FIG. 2, the worst loss of the transport path unit 11 is expressed by the following formula (3). R coil [Ω] represents the resistance value of the coil 20. R inv [Ω] represents the resistance of the inverter 21 when it is energized. crated [Arms] represents the maximum rated current value of coil 20. Worst case loss of the transport path unit = 12 × (R coil +R inv )×I crated 2 (3)

[0076] Heat is generated due to the resistance of the coil 20 and the inverter 21, and the temperature of the entire transport path unit 11 rises due to the diffusion of heat within the transport path unit 11 or the heat transfer in the substrates and the like within the transport path unit 11. When the temperature of the entire transport path unit 11 rises, the coil 20 or the inverter 21 does not exceed the allowable temperature, but the capacitor 23 or the processor 27 may exceed the allowable temperature.

[0077] 2, the length of the transport path unit 11 is longer than the length of the cart 16. In this case, it can be said that it is rare that the current values ​​of all the coils 20 in the transport path unit 11 are the maximum rated current value of the coils 20. Note that the length is the length in the traveling direction of the cart 16.

[0078] FIG. 5 is a first diagram for explaining the worst-case loss of the transport path unit 11 in the transport system 1 according to the first embodiment. FIG. 5 shows an example of a state in which the current values ​​flowing through all the coils 20 of the transport path unit 11 are the maximum rated current values ​​of the coils 20. L [mm] represents the distance between the adjacent carriages 16. In the example shown in FIG. 5, L [mm] is assumed to be as close as possible to the length of the carriage 16 in the traveling direction of the carriage 16. Here, it is assumed that there are four or more carriages 16 in the transport system 1. FIG. 5 shows a state in which four carriages 16A, 16B, 16C, and 16D are present on the transport path unit 11 with no gaps. An arrow 42 represents the traveling direction of the carriage 16.

[0079] The conveying system 1 can move the carriage 16 without reducing the rated thrust if the rated current flows only through the coils 20 of the plurality of coils 20 of the conveying path unit 11 in the portion where the carriage 16 is present. When the carriage 16 is present on all the coils 20 of the conveying path unit 11 and the carriage 16 on the conveying path unit 11 is moved continuously at the rated thrust and rated speed, the loss of the conveying path unit 11 is the worst loss. However, in the conveying system 1 which is a moving magnet type linear motor, it is considered that the operation pattern of the plurality of carriages 16 provided in the conveying system 1 is almost never the operation pattern. For this reason, it can be said that it is rare that the current value of all the coils 20 in the conveying path unit 11 is the maximum rated current value of the coils 20.

[0080] Fig. 6 is a second diagram for explaining the worst-case loss of the transport path unit 11 in the transport system 1 according to the first embodiment. Fig. 6 shows the waveform of the current flowing through one coil 20 when multiple carriages 16 pass on the transport path unit 11 without any gaps between them. That is, the waveform shown in Fig. 6 is the waveform of the current flowing through one coil 20 when the loss of the transport path unit 11 is the worst-case loss. The vertical axis shown in Fig. 6 represents the current [A] flowing through the coil 20. The horizontal axis shown in Fig. 6 represents time [s].

[0081] Here, it is assumed that four carts 16A, 16B, 16C, and 16D pass over one coil 20 in sequence. t1 is the time when the center of cart 16A comes directly above the coil 20. t2 is the time when the boundary between carts 16A and 16B comes directly above the coil 20. t3 is the time when the center of cart 16B comes directly above the coil 20. t4 is the time when the boundary between carts 16B and 16C comes directly above the coil 20. t5 is the time when the center of cart 16C comes directly above the coil 20. t6 is the time when the boundary between carts 16C and 16D comes directly above the coil 20. t7 is the time when the center of cart 16D comes directly above the coil 20.

[0082] In order to constantly apply the rated thrust to each of the carriages 16 that continue to pass without any gaps, a current with a waveform close to a sine wave, as shown in FIG. 6, is continuously passed through the coil 20. A current with the same waveform but with an appropriately different phase flows through each of the multiple coils 20 of the conveyance system 1. The effective value of the current flowing through one coil 20 when constantly applying the rated thrust to each of the carriages 16 that continue to pass without any gaps is I cratedmax Let us assume that.

[0083] Although the case where the loss of the transport path unit 11 becomes the worst loss is rare, if the transport system 1 is equipped with an overload protection function assuming the case where the loss of the transport path unit 11 becomes the worst loss, the performance of the overload protection will be excessive for the performance commensurate with the operation of the transport system 1. If a configuration for overload protection such as a cooling structure is provided in the transport path unit 11, the excessive overload protection performance will make the configuration of the transport system 1 larger than necessary, and the manufacturing cost of the transport system 1 will be higher than necessary.

[0084] In the first embodiment, the overload state of the conveying path unit 11 is a state in which the load is smaller than that in the case where the same thrust is always applied to each carriage 16 that continues to pass without leaving any interval. In other words, a loss smaller than the worst-case loss of the conveying path unit 11 is set as the maximum rated loss, which is the loss of the conveying path unit 11 when the conveying path unit 11 is in an overload state. When the loss of the conveying path unit 11 becomes the maximum rated loss, the processor 27 executes the overload protection process. This enables the conveying system 1 to provide overload protection appropriate for the operation of the conveying system 1. By enabling overload protection appropriate for the operation of the conveying system 1, it is possible to prevent the configuration of the conveying system 1 from becoming larger than necessary and the manufacturing cost of the conveying system 1 from becoming higher than necessary.

[0085] The power loss of the transport path unit 11 is expressed by the following formula (4): P load [W] represents the power loss of the transport path unit 11. coil[Arms] represents the effective value of the current flowing through the coil 20. The sum on the right side of equation (4) is the sum for all of the coils 20 in the transport path unit 11. The processor 27 calculates the loss of the transport path unit 11 using equation (4). P load =Σ(I coil 2 ) ···(4)

[0086] When the loss of the transport path unit 11 becomes the worst loss, P loadrated is expressed by the following formula (5): The sum on the right side of formula (5) is the sum for all the coils 20 in the transport path unit 11. P loadrated =Σ(I cratedmax 2 ) ···(5)

[0087] However, as described above, in the transport system 1, the effective current value in all the coils 20 in the transport path unit 11 is I cratedmax That is, it is rare that the loss in the transport path unit 11 becomes the worst loss expressed by the formula (5).

[0088] FIG. 7 is a diagram showing an example of a second overload judgment curve that is a second judgment criterion for the overload state in the transport system 1 according to the first embodiment. The second overload judgment curve, which is the second judgment criterion, represents the relationship between a second load judgment value and time. The second load judgment value is a threshold value of the loss of the transport path unit 11 when the transport path unit 11 is not in an overload state and when the transport path unit 11 is in an overload state. The vertical axis shown in FIG. 7 represents time [s]. The horizontal axis shown in FIG. 7 represents the loss of the transport path unit 11. It can also be said that the horizontal axis shown in FIG. 7 represents the amount of load applied to the transport path unit 11. Here, applying a load to the transport path unit 11 refers to a current flowing through at least one of the multiple coils 20 in the transport path unit 11.

[0089] The processor 27 calculates the effective value of the current flowing through the coil 20 based on the coil actual current value acquired from the current controller 24. The processor 27 uses the second judgment criterion, which is the relationship between the second load judgment value and the time when the load is applied to the transport path unit 11, that is, the second overload judgment curve set in advance, to compare the loss of the transport path unit 11 and the time when the load is applied to the transport path unit 11, which are calculated based on the effective value of the current flowing through each of the multiple driving units, with the second overload judgment curve, thereby judging whether the transport path unit 11 is in an overload state. In other words, the processor 27 judges whether the transport path unit 11 is in an overload state by comparing the loss of the transport path unit 11 and the time when the load is applied to the transport path unit 11 with the second judgment criterion. The second overload judgment curve, which is the second judgment criterion, may be set in advance in the processor 27, or the processor 27 may read out the second overload judgment curve set in advance by recording on a recording medium, and use the second overload judgment curve for the operation of the processor 27.

[0090] Curve 56 shown in FIG. 7 is an example of a second overload judgment curve. In curve 56, the loss value, which is the second load judgment value, decreases as time increases and becomes constant when the time exceeds a certain time. That is, in the second overload judgment curve, the second load judgment value converges to a constant value as time passes. In curve 56, P1, which is the loss value when the loss value becomes constant, is the maximum rated loss value of the transport path unit 11. In other words, the loss of the transport path unit 11 when the second load judgment value is a constant value is the maximum rated loss.

[0091] Points 57, 58, and 59 each represent a loss pattern that is a combination of the time that the load is applied to the transport path unit 11 and the loss of the transport path unit 11. In the case of the first loss pattern represented by point 57, the loss of the transport path unit 11 is smaller than the maximum rated loss. Therefore, even if the state in which the loss of the first loss pattern occurs continues, the transport path unit 11 does not enter an overload state. Therefore, the processor 27 determines that the transport path unit 11 is not in an overload state for the first loss pattern.

[0092] In the case of the second loss pattern represented by point 58, the loss of the transport path unit 11 is greater than the maximum rated loss. However, the loss of the transport path unit 11 in the second loss pattern is less than the second overload determination value represented by curve 56. In the case of the second loss pattern, the load applied to the transport path unit 11 is transient and short, and the transport path unit 11 does not enter an overloaded state. Therefore, the processor 27 determines that the transport path unit 11 is not in an overloaded state for the second loss pattern.

[0093] In the case of the third loss pattern represented by point 59, the loss of the transport path unit 11 is greater than the maximum rated loss. Also, the loss of the transport path unit 11 in the third loss pattern is greater than the second overload determination value represented by curve 56. In the case of the third loss pattern, the load applied to the transport path unit 11 is not transient but long-term, and the transport path unit 11 is in an overloaded state. Therefore, the processor 27 determines that the transport path unit 11 is in an overloaded state for the third loss pattern.

[0094] In this manner, the processor 27 determines whether the transport path unit 11 is overloaded based on the loss of the transport path unit 11 and the time that the transport path unit 11 is under load.

[0095] Here, an example of setting the maximum rated loss of the transport path unit 11 will be described. FIG. 8 is a first diagram for explaining the maximum rated loss of the transport path unit 11 in the transport system 1 according to the first embodiment. FIG. 8 shows an example of a state in which the loss of the transport path unit 11 is the maximum rated loss. L [mm] is the distance between the carts 16 when the carts 16 are lined up without any gaps as shown in FIG. 5. In FIG. 8, the distance between the adjacent carts 16 is 2L [mm]. FIG. 8 shows a state in which two carts 16A and 16B are present on the transport path unit 11 with a distance of 2L [mm] between them.

[0096] In the example described here, a plurality of carriages 16 are present at intervals corresponding to the length of one carriage 16, and the carriages 16 on the carriage path unit 11 are continuously moved at the rated thrust and rated speed. The loss of the carriage path unit 11 is defined as the maximum rated loss of the carriage path unit 11, P loadrated In this case, the maximum rated loss of the transport path unit 11 is smaller than the worst case loss of the transport path unit 11.

[0097] When the carriages 16 on the transport path unit 11 are continuously moved at the rated thrust and rated speed, it is assumed that the case where the interval between the carriages 16 becomes smaller than the length of one carriage 16 is rare. By setting the loss in an operation pattern in which a plurality of carriages 16 are present at intervals equivalent to the length of one carriage 16 and the carriages 16 on the transport path unit 11 are continuously moved at the rated thrust and rated speed as the maximum rated loss, many operation patterns that the transport system 1 can take can be continued without any problems. In addition, the transport system 1 can appropriately protect the transport path unit 11 from overload by an overload protection function with performance that matches the operation of the transport system 1.

[0098] FIG. 9 is a second diagram for explaining the maximum rated loss of the transport path unit 11 in the transport system 1 according to the first embodiment. FIG. 9 shows the waveform of the current flowing through one coil 20 when a plurality of carriages 16 are present at intervals corresponding to the length of one carriage 16 and the carriages 16 on the transport path unit 11 are continuously moved at rated thrust and rated speed. That is, the waveform shown in FIG. 9 is the waveform of the current flowing through one coil 20 when the loss of the transport path unit 11 is the maximum rated loss. The vertical axis shown in FIG. 9 represents the current [A] flowing through the coil 20. The horizontal axis shown in FIG. 9 represents time [s].

[0099] Here, it is assumed that two carts 16A and 16B pass successively over one coil 20 with an interval of 2L [mm] between them. t11 is the time when the center of cart 16A comes directly above the coil 20. t12 is the time when the center of cart 16B comes directly above the coil 20.

[0100] I crated1 is the effective value of the current flowing through one coil 20 when the loss of the transport path unit 11 is the maximum rated loss. cratedmax As described with reference to FIG. 6, I is the effective value of the current flowing through one coil 20 when the loss in the transport path unit 11 is the worst case loss. crated1 I cratedmax Less than.

[0101] The maximum rated loss of the transport path unit 11 is P loadrated is expressed by the following formula (6): The sum on the right side of formula (6) is the sum for all the coils 20 in the transport path unit 11. P loadrated =Σ(I crated1 2 ) ···(6)

[0102] I crated1 cratedmax and equation (6), the following equation (7) holds. P loadrated <Σ(I cratedmax ​2 ) ···(7)

[0103] Equation (7) expresses the maximum rated loss of the transport path unit 11, P loadrated represents that the current flowing through each of the coils 20 in the transport path unit 11 is smaller than the loss of the transport path unit 11 when the current flowing through each of the coils 20 is the maximum rated current value of the coils 20. In the transport system 1, the maximum rated loss of the transport path unit 11, P loadrated By satisfying the formula (7), many possible operation patterns of the conveying system 1 can be continued without any problems, and the conveying path unit 11 can be appropriately protected from overload.

[0104] In the above description, the maximum rated loss is defined as the loss when the interval between the multiple bogies 16 is equivalent to the length of one bogie 16, but this is not limited to the above. The maximum rated loss can be set arbitrarily as long as it is smaller than the worst-case loss. For example, the maximum rated loss may be the loss when the interval between the multiple bogies 16 is equivalent to half the length of the bogie 16.

[0105] The maximum rated loss value may be the same for a plurality of transport path units 11, or may be different for each transport path unit 11. For example, the maximum rated loss value of each transport path unit 11 may be a value adjusted based on the size of the housing of the transport path unit 11 or the type of electronic components used in the transport path unit 11. Alternatively, the linear transport path unit 11 and the curved transport path unit 11 may have different maximum rated loss values.

[0106] In the transport system 1, the second load judgment value in the second overload judgment curve, which is the second judgment criterion, may be different for each transport path unit 11. In other words, a different second load judgment value may be set for each of the multiple transport path units 11. In this case, the transport system 1 may set a second load judgment value adjusted in accordance with the configuration of the transport path unit 11. The transport system 1 is able to judge whether or not the transport path unit 11 is in an overloaded state, taking into account the configuration of the transport path unit 11.

[0107] Next, a specific example of the overload protection process when it is determined that the transport path unit 11 is in an overloaded state will be described. When it is determined that the transport path unit 11 is in an overloaded state, the processor 27 transmits an alarm indicating the overloaded state to each transport path unit 11 of the transport system 1.

[0108] The processor 27 of each transport path unit 11 executes overload protection processing upon receiving the alarm. In this example, upon receiving the alarm, the processor 27 of each transport path unit 11 stops the current supply to each drive unit by the current controller 24 as the overload protection processing. Alternatively, upon receiving the alarm, the processor 27 of each transport path unit 11 reduces the amount of current flowing to each drive unit as the overload protection processing. In this way, the processor 27 of each transport path unit 11 performs control to stop or decelerate all the carts 16 present in the transport system 1. In this example, when one of the multiple transport path units 11 is determined to be in an overload state, the multiple transport path units 11 stop or decelerate all the carts 16 present on the transport path 10 by the overload protection processing.

[0109] In this way, each transport path unit 11 executes an overload protection process to reduce the temperature of the transport path unit 11 by reducing the load of the transport path unit 11 or reducing the load of the transport path unit 11. The transport system 1 can avoid problems such as burnout due to overheating by stopping or slowing down all the carriages 16 present on the transport path 10 through the overload protection process. Note that each transport path unit 11 may decelerate and then stop each carriage 16, as in the case where the drive unit is determined to be in an overloaded state. Each transport path unit 11 may activate a regenerative brake by shorting the coil 20 through the overload protection process.

[0110] In the above description, all the carriages 16 present on the conveying path 10 are stopped or decelerated by the overload protection process, but the overload protection process executed by the conveying system 1 is not limited to this. When one of the plurality of conveying path units 11 is determined to be in an overloaded state, only the conveying path unit 11 determined to be in an overloaded state may stop or decelerate the carriage 16 by the overload protection process. In this case, the carriages 16 present on the conveying path 10 composed of the conveying path units 11 other than the conveying path unit 11 determined to be in an overloaded state are not stopped or decelerated. Then, when only the conveying path unit 11 determined to be in an overloaded state stops or decelerates the carriage 16 by the overload protection process, all the carriages 16 present on the conveying path unit 11 determined to be in an overloaded state may be stopped or decelerated, or some of the carriages 16 present on the conveying path unit 11 determined to be in an overloaded state may be stopped or decelerated. In this case, the conveying system 1 can also avoid defects such as burnout due to overheating.

[0111] In the above description, the processor 27 acquires the actual coil current value detected by the current sensor 22, and determines whether the transport path unit 11 is in an overloaded state based on the effective current value calculated based on the actual coil current value. That is, the processor 27 determines whether the transport path unit 11 is in an overloaded state based on the effective value of the current flowing through each of the multiple driving units. In this case, the processor 27 estimates the load of the transport path unit 11 from the detection result of the current flowing through each of the multiple driving units. The processor 27 may estimate the load of the transport path unit 11 from the detection result of the temperature of the transport path unit 11. That is, the processor 27 may determine whether the transport path unit 11 is in an overloaded state based on the temperature detected by the temperature sensor 34. That is, when estimating the load of the transport path unit 11 from the detection result of the temperature of the transport path unit 11, the loss P of the transport path unit 11 is calculated by using the temperature detected by the temperature sensor 34 instead of the sum of the effective values ​​of the currents flowing through all the coils 20 in the transport path unit 11 used in calculating the loss of the transport path unit 11 described above. load and P, the maximum rated loss of the transport path unit 11. loadrated By calculating the above, a second overload judgment curve, which is the second judgment criterion, can be set in advance. In this case, too, the conveyance system 1 can avoid problems such as burnout due to overheating.

[0112] In the above description, the processor 27 stops the power supply to the drive unit or reduces the amount of current flowing to the drive unit as the overload protection process, but the overload protection process is not limited to these. The processor 27 may also reduce the switching frequency of the inverter 21 as the overload protection process. The transport path unit 11 may be provided with a cooling structure that cools the inside of the transport path unit 11. The cooling structure is, for example, a fan. The processor 27 may also operate the cooling structure as the overload protection process. When performing these overload protection processes, the transport path unit 11 can also reduce the temperature of the drive unit determined to be in an overloaded state or the temperature of the transport path unit 11 determined to be in an overloaded state.

[0113] According to the first embodiment, the conveying system 1 determines whether each of the multiple driving units is in an overloaded state in the processor 27, and determines whether the conveying path unit 11 is in an overloaded state. In each of the multiple conveying path units 11, the processor 27 executes an overload protection process to lower the temperature of the driving unit determined to be in an overloaded state or the temperature of the conveying path unit 11 determined to be in an overloaded state. By separating the determination for the driving unit from the determination for the conveying path unit 11, the conveying system 1 does not lower the maximum load, which is the maximum allowable load for each driving unit, and can lower the maximum allowable load for the entire conveying path unit 11 compared to when all of the driving units of the conveying path unit 11 are at maximum load. By not lowering the maximum load for each driving unit, the conveying system 1 can move the cart 16 without lowering the rated thrust. The conveying system 1 can provide overload protection appropriate to the operation of the conveying system 1 by lowering the maximum allowable load for the entire conveying path unit 11. As a result, the transport system 1 has an advantage in that overload protection suited to the operation of the transport system 1 is possible.

[0114] Embodiment 2 In the transport system 1, the transport path units 11 are adjacent to each other. For example, when the temperature of a first transport path unit, which is one of the two adjacent transport path units 11, rises, the heat of the first transport path unit may be transferred to the second transport path unit, which is the other transport path unit 11, thereby causing the temperature of the second transport path unit to rise. For this reason, even if it is determined from the driving state of the second transport path unit that the second transport path unit is not in an overload state, the second transport path unit may become in an overheated state due to heat conduction from the first transport path unit. In this case, it becomes difficult to appropriately protect the second transport path unit from overload.

[0115] In the second embodiment, a first example of overload protection for preventing the transport path units 11 from becoming overheated due to heat being applied from one of the adjacent transport path units 11 to the other will be described. The transport system 1 according to the second embodiment has a similar configuration to the transport system 1 according to the first embodiment. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and processing different from that in the first embodiment will be mainly described.

[0116] In the second embodiment, the processor 27 of each of the plurality of transport path units 11 judges whether the transport path unit 11 is in a high load state. The high load state is a state in which the load is smaller than the overload state and is expected to reach the overload state. When one of the plurality of transport path units 11 is judged to be in a high load state, the processor 27 of the second transport path unit, which is the transport path unit 11 adjacent to the first transport path unit, which is the transport path unit 11 judged to be in a high load state, corrects the second load judgment value to be smaller than a preset value in the relationship represented by the second overload judgment curve preset as the second judgment criterion. The processor 27 of the second transport path unit judges whether the second transport path unit is in an overload state based on the second judgment criterion corrected to make the second load judgment value smaller than a preset value.

[0117] The power loss, which is the loss in the transport path unit 11, is expressed by the above formula (4). The processor 27 calculates the loss in the transport path unit 11 using formula (4).

[0118] The transport path unit 11 is preset with a loss value that is a threshold for determining whether the transport path unit 11 is in a high load state. Here, the loss value that is the threshold is called a high load determination value. The processor 27 calculates the loss P load The value of and the high load judgment value P loadh Compare with.

[0119] P load >Ploadh is satisfied, the processor 27 determines that the transport path unit 11 is in a high-load state. When the processor 27 determines that the transport path unit 11 is in a high-load state, it transmits an alarm indicating that the transport path unit 11 is in a high-load state to the controller 12. The first transport path unit, which is the transport path unit 11 determined to be in a high-load state, notifies the controller 12 that the first transport path unit is in a high-load state by transmitting an alarm.

[0120] When the controller 12 receives an alarm from the first transport path unit, the controller 12 transmits an alarm indicating that the first transport path unit is in a high load state to the second transport path unit. For example, when the transport path unit 11A in the transport system 1 shown in FIG. 1 is the first transport path unit, each of the transport path unit 11B and the transport path unit 11H is the second transport path unit.

[0121] When the processor 27 of the second transport path unit receives the alarm from the controller 12, the processor 27 of the second transport path unit 11 calculates the maximum rated loss P loadrated to a value smaller than a preset value. That is, the processor 27 of the second transport path unit corrects the second load judgment value in the second overload judgment curve to a value smaller than a preset value. In this way, the processor 27 of the second transport path unit corrects the second judgment criterion represented by the second overload judgment curve upon being notified by the controller 12 that the first transport path unit is in a high load state.

[0122] The processor 27 of the second transport path unit judges whether the second transport path unit is in an overload state based on the second overload judgment curve, which is the modified second judgment criterion. This allows the transport system 1 to appropriately execute overload protection processing for the second transport path unit when the temperature of the second transport path unit increases due to heat conduction from the first transport path unit.

[0123] According to the second embodiment, when the first transport path unit is in a high load state, the transport system 1 applies a correction to the second overload judgment curve to make the second load judgment value smaller than a preset value in the second transport path unit. This makes it possible for the transport system 1 to prevent the transport path units 11 from becoming overheated due to heat being applied from one of the adjacent transport path units 11 to the other.

[0124] Embodiment 3 In the third embodiment, a second example of overload protection for preventing the transport path units 11 from becoming overheated due to heat being applied from one of the adjacent transport path units 11 to the other will be described. The transport system 1 according to the third embodiment has a similar configuration to the transport system 1 according to the first embodiment. In the third embodiment, the same components as those in the first or second embodiment are denoted by the same reference numerals, and processing different from the first or second embodiment will be mainly described.

[0125] In the second embodiment, the processor 27 of each transport path unit 11 determines whether or not the transport path unit 11 is in a high-load state. In the third embodiment, the controller 12 determines whether or not each of the multiple transport path units 11 is in a high-load state.

[0126] The power loss of the transport path unit 11 is expressed by the above formula (4). The processor 27 of each transport path unit 11 calculates the loss of the transport path unit 11 by formula (4). The processor 27 calculates the loss P load The value of is sent to the controller 12.

[0127] The controller 12 includes a high load determination value P loadh The controller 12 calculates the loss P load Value of and P loadhIn this way, the controller 12 determines whether or not each of the plurality of transport path units 11 is in a high load state.

[0128] P load >P loadh If there is a transport path unit 11 for which load >P loadh is determined to be in a high-load state. The controller 12 transmits an alarm indicating that the first transport path unit is in a high-load state to a second transport path unit adjacent to the first transport path unit determined to be in a high-load state. By transmitting the alarm, the controller 12 notifies the second transport path unit that the first transport path unit is in a high-load state.

[0129] When the processor 27 of the second transport path unit receives the alarm from the controller 12, the processor 27 of the second transport path unit 11 calculates the maximum rated loss P loadrated to a value smaller than a preset value. That is, the processor 27 of the second transport path unit corrects the second load judgment value in the second overload judgment curve to a value smaller than a preset value. In this way, the processor 27 of the second transport path unit corrects the second judgment criterion represented by the second overload judgment curve upon being notified by the controller 12 that the first transport path unit is in a high load state.

[0130] The processor 27 of the second transport path unit judges whether the second transport path unit is in an overloaded state based on the second overload judgment curve, which is the second judgment criterion after the correction. This allows the second transport path unit to execute an overload protection process when the second transport path unit is in an overloaded state due to a temperature rise caused by heat conduction from the first transport path unit.

[0131] In the above description, the processor 27 of the second transport path unit corrects the second load judgment value to a value smaller than a preset value. In the third embodiment, the controller 12 may correct the second load judgment value to a value smaller than a preset value. In this case, the controller 12 holds a second judgment criterion represented by a second overload judgment curve for each of the multiple transport path units 11. The controller 12 corrects the second judgment criterion represented by the second overload judgment curve for the second transport path unit adjacent to the first transport path unit determined to be in a high load state. The controller 12 transmits information indicating the corrected second judgment criterion to the second transport path unit.

[0132] The processor 27 of the second transport path unit determines whether or not the second transport path unit is in an overload state based on the second overload determination curve, which is the modified second determination criterion, by acquiring the information transmitted from the controller 12. This allows the transport system 1 to appropriately perform overload protection processing for the second transport path unit when the temperature of the second transport path unit increases due to heat conduction from the first transport path unit.

[0133] The controller 12 determines that the first transport path unit is in a high load state. load Depending on the value of P loadrated For example, the load factor P of the first transport path unit may be adjusted. load / P loadh is 0.9, the controller 12 sets the maximum rated loss P loadrated By multiplying the value of by 0.9, P of the second transport path unit loadrated In this method, the value of P of the second transport path unit is adjusted by multiplying the load factor of the first transport path unit. loadrated The controller 12 adjusts the value of P load Depending on the value of P of the second transport path unit by any method. loadratedThe value of P of the second transport path unit can be adjusted. loadrated A program for adjusting the value of is preset in the controller 12.

[0134] According to the third embodiment, when the first transport path unit is in a high load state, the transport system 1 applies a correction to the second overload judgment curve in the second transport path unit to make the second load judgment value smaller than a preset value in the second transport path unit. This makes it possible for the transport system 1 to prevent the transport path units 11 from becoming overheated due to heat being applied from one of the adjacent transport path units 11 to the other.

[0135] Embodiment 4 In the conveyance system 1 according to the first to third embodiments, the controller 12 generates an operation command indicating a movement mode for each of the multiple carriages 16, and generates a position command for each carriage 16 based on the operation command. The operation command includes information on the movement of the carriage 16, such as acceleration, deceleration, and movement speed. In the fourth embodiment, an example in which machine learning is applied to the generation of the operation command will be described.

[0136] For example, assume that operation information is acquired indicating that the trolley 16 is to reach a destination position 3 m ahead of the current position 2 seconds after a certain point in time. In this case, any pattern can be taken as a pattern of a motion command for moving the trolley 16. One of the possible patterns is a pattern in which the trolley 16 is moved by trapezoidal acceleration / deceleration from the start point to the end point of the two seconds. Other patterns include a pattern in which the trolley 16 is moved by trapezoidal acceleration / deceleration for one second from the start point and stopped for the remaining one second, or a pattern in which the trolley 16 is stopped for one second from the start point and moved by trapezoidal acceleration / deceleration for the remaining one second. There are an infinite number of patterns that can be taken as a pattern of a driving command for the acquired operation information.

[0137] In the transport system 1, it is preferable that the maximum value among the multiple transport path units 11 among the values ​​of power consumed in each transport path unit 11 is as small as possible. In the following description, the maximum value among the multiple transport path units 11 among the values ​​of power used in each transport path unit 11 is referred to as the maximum power value. In the fourth embodiment, an operation command that reduces the maximum power value is derived by machine learning from an infinite number of patterns of operation commands.

[0138] 10 is a diagram showing an example of the configuration of a controller 60 provided in the transportation system 1 according to the fourth embodiment. The controller 60 includes a learning device 61, an operation command generator 62, a position command generator 63, and a coil drive command generator 64.

[0139] Operation information 65 is input to the operation command generator 62. The operation command generator 62 generates an operation command 67 based on the operation information 65. The operation command 67 generated by the operation command generator 62 is input to a position command generator 63. The position command generator 63 generates a position command 68 based on the operation command 67. The position command 68 generated by the position command generator 63 is input to a coil drive command generator 64.

[0140] The coil drive command generator 64 generates a coil drive command 69 based on the position command 68. The controller 60 transmits the coil drive command 69 generated by the coil drive command generator 64 to each transport path unit 11. The controller 60 controls the movement of each carriage 16 by transmitting the coil drive command 69 to each transport path unit 11.

[0141] Operation information 65 and operation commands 67 are input to the learning device 61. The learning device 61 learns the relationship between the operation information 65 and the operation commands 67 that reduce the maximum power value. The learning device 61 outputs a learned model 66 that is the result of learning. The operation command generator 62 acquires the learned model 66 from the learning device 61. The operation command generator 62 inputs the operation information 65 to the learned model 66, thereby inferring the operation command 67 that reduces the maximum power value. The operation command generator 62 generates the operation command 67 based on this inference.

[0142] 11 is a diagram illustrating a configuration example of a learning device 61 included in a controller 60 according to the fourth embodiment. The learning device 61 includes a data acquiring unit 71, a model generating unit 72, and a learned model storage unit 75.

[0143] The data acquiring unit 71 acquires learning data 76 and creates a data set by compiling the learning data 76. The learning data 76 includes operation information 65 and driving commands 67. That is, the data acquiring unit 71 acquires the learning data 76 including the operation information 65 and the driving commands 67. The learning data 76 is input to the model generating unit 72.

[0144] The model generation unit 72 generates the trained model 66 by using the learning data 76. The model generation unit 72 generates the trained model 66 used to infer an operation command 67 from the operation information 65, based on the learning data 76. The trained model storage unit 75 stores the trained model 66.

[0145] The learning algorithm used by the model generation unit 72 may be a known algorithm such as supervised learning, unsupervised learning, or reinforcement learning. As an example, a case where reinforcement learning is applied to the learning algorithm used by the model generation unit 72 will be described. In reinforcement learning, an agent acting as an agent in a certain environment observes the current state and determines the action to be taken. The agent obtains a reward from the environment by selecting an action, and learns a policy that will obtain the most reward through a series of actions. Q-learning and TD-learning are known as representative methods of reinforcement learning.

[0146] For example, in the case of Q-learning, the action value table, which is a general update formula for the action value function Q(s, a), is expressed by the following formula (8). The action value function Q(s, a) represents the action value Q, which is the value of the action of selecting action "a" in environment "s".

[0147]

number

[0148] In formula (8), "s t " represents the environment at time "t". t " represents an action at time "t". t "The environment is "s t+1 " will be changed to "r t+1 " represents the reward that can be obtained by the change in the environment. "γ" represents the discount rate. "γ" satisfies 0<γ≦1. "α" represents the learning coefficient. "α" satisfies 0<α≦1. When the operation information 65 changes the environment "s t " Operation command 67 is action "a t "

[0149] The update formula expressed by formula (8) increases the action value Q if the action value of the best action "a" at time "t+1" is greater than the action value Q of the action "a" executed at time "t", and decreases the action value Q in the opposite case. In other words, the action value function Q(s,a) is updated so that the action value Q of the action "a" at time "t" approaches the best action value at time "t+1". As a result, the best action value in a certain environment is propagated sequentially to the action value in the previous environment.

[0150] The model generation unit 72 includes a reward calculation unit 73 and a function update unit 74. The reward calculation unit 73 calculates a reward based on a data set. The function update unit 74 updates a function for determining the driving command 67 according to the reward calculated by the reward calculation unit 73.

[0151] Specifically, the reward calculation unit 73 calculates the reward "r" based on the maximum power value. For example, when the maximum power value decreases, the reward calculation unit 73 increases the reward "r". The reward calculation unit 73 increases the reward "r" by giving a reward value of "1". Note that the reward value is not limited to "1". On the other hand, when the maximum power value increases, the reward calculation unit 73 decreases the reward "r". The reward calculation unit 73 decreases the reward "r" by giving a reward value of "-1". Note that the reward value is not limited to "-1".

[0152] The function update unit 74 updates the function, which is a model for determining the driving command 67, according to the reward calculated by the reward calculation unit 73. The function can be updated by, for example, updating an action value table according to a data set. The action value table is a data set in which any action is associated with its action value and stored in the form of a table. For example, in the case of Q-learning, the action value function Q(s t ,a t ) is used as a function for determining the operation command 67.

[0153] Fig. 12 is a flowchart showing a processing procedure of the learning device 61 provided in the controller 60 according to the embodiment 4. A reinforcement learning method for updating the action value function Q(s, a) will be described with reference to the flowchart of Fig. 12.

[0154] In step S11, the learning device 61 acquires the operation information 65 and the driving command 67 by the data acquisition unit 71. That is, the learning device 61 acquires the learning data 76. The data acquisition unit 71 outputs a data set in which the learning data 76 is compiled to the model generation unit 72.

[0155] In step S12, the learning device 61 calculates a reward by the reward calculation unit 73. The reward calculation unit 73 calculates a reward for a combination of the operation information 65 for each bogie 16 and the operation command 67 for each bogie 16. The reward calculation unit 73 increases or decreases the reward based on the maximum power value.

[0156] In step S13, the learning device 61 updates the action value function by the function update unit 74. The function update unit 74 updates the action value function Q(s, a) based on the reward calculated in step S12. The learning device 61 updates the action value function Q(s t ,a t ) to update the

[0157] In step S14, the learning device 61 judges whether or not the action value function Q(s, a) has converged by the function update unit 74. The function update unit 74 judges that the action value function Q(s, a) has converged because the update of the action value function Q(s, a) in step S13 is no longer performed.

[0158] If it is determined that the action value function Q(s, a) has not converged (step S14, No), the learning device 61 returns the procedure to step S11. On the other hand, if it is determined that the action value function Q(s, a) has converged (step S14, Yes), the learning device 61 ends the processing according to the procedure shown in FIG. 12. Note that the learning device 61 may continue learning by returning the procedure from step S13 to step S11 without making the judgment in step S14. The learned model storage unit 75 stores the learned model 66, which is the generated action value function Q(s, a).

[0159] In the fourth embodiment, a case has been described in which reinforcement learning is applied to the learning algorithm used by the learning device 61, but learning other than reinforcement learning may be applied to the learning algorithm. The learning device 61 may execute machine learning using a known learning algorithm other than reinforcement learning, such as a learning algorithm such as deep learning, a neural network, genetic programming, inductive logic programming, or a support vector machine.

[0160] The learning device 61 shown in FIG. 10 and FIG. 11 is a device built into the controller 60. The learning device 61 may be a device external to the controller 60. The learning device 61, which is a device external to the controller 60, constitutes the transportation system 1. The learning device 61 may be a device connectable to the controller 60 via a network. The learning device 61 may be a device present on a cloud server. In the example shown in FIG. 11, the learned model storage unit 75 is built into the learning device 61. The learned model storage unit 75 may be provided outside the learning device 61.

[0161] The learning device 61 may learn an operation command 67 that reduces the maximum power value according to a data set created for a plurality of transportation systems 1. The learning device 61 may acquire operation information 65 and operation commands 67 from a plurality of transportation systems 1 used in the same place, or may acquire operation information 65 and operation commands 67 from a plurality of transportation systems 1 used in different places. The operation information 65 and operation commands 67 may be collected from a plurality of transportation systems 1 that operate independently of each other in a plurality of places. After starting to collect the operation information 65 and operation commands 67 from the plurality of transportation systems 1, a new transportation system 1 may be added to the targets from which the operation information 65 and operation commands 67 are collected. In addition, after starting to collect the operation information 65 and operation commands 67 from the plurality of transportation systems 1, some of the plurality of transportation systems 1 may be excluded from the targets from which the operation information 65 and operation commands 67 are collected.

[0162] The learning device 61 that has learned about one transportation system 1 may learn about another transportation system 1 other than the transportation system 1. The learning device 61 that learns about the other transportation system 1 can update the learned model 66 by re-learning in the other transportation system 1.

[0163] 13 is a diagram showing a configuration example of the operation command generator 62 provided in the controller 60 according to the fourth embodiment. The operation command generator 62 has a function as an inference device that infers an operation command 67 from operation information 65. The operation command generator 62 has a data acquisition unit 77 and an inference unit 78.

[0164] The data acquisition unit 77 receives operation information 65 for each of the multiple carts 16 included in the conveyance system 1. The data acquisition unit 77 acquires the operation information 65, which is data for inference. The operation information 65 acquired by the data acquisition unit 77 is input to the inference unit 78. The learned model 66 stored in the learned model storage unit 75 of the learning device 61 is input to the inference unit 78. The inference unit 78 infers an operation command 67 by inputting the operation information 65 to the learned model 66. The inference unit 78 outputs the operation command 67, which is the inference result, to the position command generator 63.

[0165] FIG. 14 is a flowchart showing the processing procedures of the operation command generator 62, the position command generator 63, and the coil drive command generator 64 provided in the controller 60 according to the fourth embodiment.

[0166] In step S21, the operation command generator 62 acquires the operation information 65 of each bogie 16 by the data acquisition unit 77. The data acquisition unit 77 outputs the acquired operation information 65 to the inference unit 78.

[0167] In step S22, the driving command generator 62 generates a driving command 67 by inputting the operation information 65 to the trained model 66 in the inference unit 78. The driving command generator 62 outputs the generated driving command 67 to the position command generator 63.

[0168] In step S23, the position command generator 63 generates a position command 68 based on the operation command 67. The position command generator 63 outputs the generated position command 68 to the coil drive command generator 64.

[0169] In step S24, the coil drive command generator 64 generates a coil drive command 69 based on the position command 68. The coil drive command generator 64 transmits the generated coil drive command 69 to each transport path unit 11 via the data communication line 14. With the above, the operation command generator 62, the position command generator 63, and the coil drive command generator 64 end the processing according to the procedure shown in FIG.

[0170] According to the fourth embodiment, the conveying system 1 includes a learning device 61 and an operation command generator 62, which is an inference device, and is thereby able to derive an operation command 67 that reduces the maximum power value. This enables the conveying system 1 to reduce the load on each conveying path unit 11.

[0171] Next, a description will be given of hardware for realizing the controllers 12 and 60 according to the first to fourth embodiments. The controllers 12 and 60 are realized by a processing circuit. The processing circuit may be a circuit in which a processor executes software, or may be a dedicated circuit.

[0172] When the processing circuit is realized by software, the processing circuit is, for example, a control circuit 80 shown in Fig. 15. Fig. 15 is a diagram showing a configuration example of the control circuit 80 according to the first to fourth embodiments. The control circuit 80 includes an input unit 81, a processor 82, a memory 83, and an output unit 84. The input unit 81 is an interface circuit that receives data input from outside the control circuit 80 and provides the data to the processor 82. The output unit 84 is an interface circuit that transmits data from the processor 82 or the memory 83 to outside the control circuit 80.

[0173] When the processing circuit is the control circuit 80 shown in FIG. 15, the controller 12, 60 is realized by software, firmware, or a combination of software and firmware. The software or firmware is written as a program and stored in the memory 83. The processing circuit realizes each function of the controller 12, 60 by the processor 82 reading and executing the program stored in the memory 83. That is, the processing circuit includes the memory 83 for storing the program that results in the processing of the controller 12, 60. It can also be said that these programs cause a computer to execute the procedures and methods of the controller 12, 60.

[0174] The processor 82 is a CPU. The processor 82 may be a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, a processor, or a DSP. The memory 83 may be, for example, a non-volatile or volatile semiconductor memory such as a random access memory (RAM), a read only memory (ROM), a flash memory, an erasable programmable read only memory (EPROM), an electrically erasable programmable read only memory (EEPROM (registered trademark)), a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, or a digital versatile disk (DVD).

[0175] Fig. 15 shows an example of hardware in which the controllers 12, 60 are realized by a general-purpose processor 82 and a memory 83, but the controllers 12, 60 may be realized by a dedicated hardware circuit. Fig. 16 is a diagram showing an example of the configuration of a dedicated hardware circuit 85 according to the first to fourth embodiments.

[0176] The dedicated hardware circuit 85 includes an input unit 81, an output unit 84, and a processing circuit 86. The processing circuit 86 is a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a circuit that combines these. Each function of the controllers 12, 60 may be realized by the processing circuit 86 separately for each function, or each function may be realized collectively by the processing circuit 86. The controllers 12, 60 may be realized by combining the control circuit 80 and the hardware circuit 85.

[0177] When the learning device 61 is an external device to the controller 60, the learning device 61 is realized by a processing circuit, similar to the controllers 12 and 60. The processing circuit that realizes the learning device 61 is the control circuit 80 shown in FIG. 15 or a dedicated hardware circuit 85 shown in FIG.

[0178] The specific form of distribution or integration of each component in the transport system 1 according to the first to fourth embodiments is not limited to those described in the first to fourth embodiments. All or part of the components of the transport system 1 may be functionally or physically distributed or integrated in any unit.

[0179] The configurations shown in the above embodiments are examples of the contents of the present disclosure. The configurations of each embodiment can be combined with other known technologies. The configurations of each embodiment can be appropriately combined. A part of the configuration of each embodiment can be omitted or modified without departing from the gist of the present disclosure. [Explanation of symbols]

[0180] 1 conveyor system, 10 conveyor path, 11, 11A, 11B, 11C, 11D, 11E, 11F, 11G, 11H conveyor path unit, 12, 60 controller, 13 DC power supply, 14 data communication line, 15 DC power bus, 16, 16A, 16B, 16C, 16D trolley, 17A, 17B, 42 arrow, 20 coil, 21 inverter, 22 current sensor, 23 capacitor, 24 current controller, 25 linear scale, 26 position sensor, 27, 82 processor, 28 communication slave station, 31 P bus, 32 N bus, 33 voltage detector, 34 temperature sensor, 40, 41 permanent magnet, 51, 52, 56 curve, 53, 54, 55, 57, 58, 59 point, 61 learning device, 62 operation command generator, 63 Position command generator, 64 coil drive command generator, 65 operation information, 66 trained model, 67 driving command, 68 position command, 69 coil drive command, 71, 77 data acquisition unit, 72 model generation unit, 73 reward calculation unit, 74 function update unit, 75 trained model storage unit, 76 learning data, 78 inference unit, 80 control circuit, 81 input unit, 83 memory, 84 output unit, 85 hardware circuit, 86 processing circuit.

Claims

1. A plurality of conveying path units are provided which constitute a conveying path along which one or a plurality of conveying bodies move, Each of the plurality of transport path units includes: a plurality of driving units that generate a thrust for moving the conveying body by the flow of an electric current; a processor that determines whether each of the plurality of drive units is in an overload state and determines whether the transport path unit is in an overload state, A transport system characterized in that, in each of the plurality of transport path units, the processor executes an overload protection process to reduce the temperature of the drive unit that has been determined to be in an overloaded state or the temperature of the transport path unit that has been determined to be in an overloaded state.

2. The conveying system according to claim 1, characterized in that when it is determined that at least one of the multiple drive units in one of the multiple conveying path units is in an overloaded state, or when it is determined that the conveying path unit in one of the multiple conveying path units is in an overloaded state, the multiple conveying path units stop or slow down all of the conveying bodies present in the conveying path by the overload protection process.

3. The conveying system according to claim 1, characterized in that when it is determined that at least one of the multiple drive units in one of the multiple conveying path units is in an overloaded state, the conveying path unit including the drive unit determined to be in an overloaded state stops or decelerates the conveying body by the overload protection process.

4. The conveying system according to claim 1, characterized in that when it is determined that one of the plurality of conveying path units is in an overloaded state, the conveying path unit determined to be in an overloaded state stops or slows down the conveying body by the overload protection process.

5. The conveying system according to claim 1, characterized in that when it is determined that at least one of the plurality of drive units in one of the plurality of conveying path units is in an overloaded state, the processor of the conveying path unit including the drive unit determined to be in an overloaded state stops the supply of electricity to the drive unit determined to be in an overloaded state.

6. The drive unit includes an element to be monitored for overload status, 6. The transportation system according to claim 1, wherein the processor determines whether the element is in an overloaded state by comparing a first load determination value, which is a threshold value of a current flowing through the element when the element is not in an overloaded state and when the element is in an overloaded state, with a first determination criterion that is a relationship between a first load determination value, which is a threshold value of a current flowing through the element, and a time during which the current flows through the element, and an effective value of the current flowing through the element and a time during which the current flows through the element.

7. the driving unit includes a first element and a second element that are the elements to be monitored, The first element is an inverter, 7. The transport system according to claim 6, wherein the second element is a coil that generates an electromagnetic force, which is the thrust, by power supplied from the inverter.

8. The transport path unit is configured to determine whether or not the transport path unit is in an overloaded state by comparing the loss of the transport path unit and the time during which a load is applied to the transport path unit with a second load determination value, which is a threshold value for loss of the transport path unit when the transport path unit is not in an overloaded state and when the transport path unit is in an overloaded state, and a second determination criterion, which is a relationship between the loss of the transport path unit and the time during which a load is applied to the transport path unit, when the transport path unit is not in an overloaded state and when the transport path unit is in an overloaded state.

9. 9. The transport system according to claim 8, wherein the second load judgment value can be set differently for each of the plurality of transport path units.

10. In the second judgment criterion, the second load judgment value converges to a constant value over time; 9. The transport system according to claim 8, wherein a maximum rated loss, which is a loss of the transport path unit when the second load determination value is the constant value, is smaller than a loss of the transport path unit when a value of a current flowing through each of the plurality of drive units is a maximum rated current value of the drive unit.

11. 6. The transport system according to claim 1, wherein the processor determines whether or not the transport path unit is in an overload state based on an effective value of a current flowing through the plurality of driving parts.

12. 6. The transport system according to claim 1, wherein the processor determines whether or not the transport path unit is in an overloaded state based on a result of detection of the temperature of the transport path unit.

13. The processor of each of the plurality of transport path units determines whether the transport path unit is in a high load state, which is a state in which the transport path unit is expected to reach an overload state; The transport system according to claim 8, characterized in that, when one of the plurality of transport path units is determined to be in the high-load state, the processor of the second transport path unit, which is the transport path unit adjacent to the first transport path unit, which is the transport path unit determined to be in the high-load state, determines whether or not the second transport path unit is in an overloaded state based on the second judgment criterion that has been modified to make the second load judgment value smaller than a preset value.

14. A controller for controlling the movement of the conveyor is provided, the first transport path unit that has been determined to be in the high-load state notifies the controller that the first transport path unit is in the high-load state; 14. The transport system according to claim 13, wherein the processor of the second transport path unit applies the correction to the second judgment criterion when the processor is notified by the controller that the first transport path unit is in a high load state.

15. A controller for controlling the movement of the conveyor is provided, the controller determines whether or not each of the plurality of transport path units is in a high load state, which is a state that is expected to reach an overload state; The transport system according to claim 8, characterized in that, when one of the plurality of transport path units is determined to be in the high-load state, the processor of the second transport path unit, which is the transport path unit adjacent to the first transport path unit, which is the transport path unit determined to be in the high-load state, determines whether or not the second transport path unit is in an overloaded state based on the second judgment criterion that has been modified to make the second load judgment value smaller than a preset value.

16. The transport system according to claim 15, wherein the controller applies the modification to the second judgment criterion for the second transport path unit and notifies the second transport path unit of the modified second judgment criterion.

17. A data acquisition unit that acquires learning data including operation information that is information indicating a schedule for the movement of each of the plurality of conveyance bodies on the conveyance path and an operation command that indicates a movement mode for each of the plurality of conveyance bodies; a model generation unit that generates a trained model used for inferring the driving command from the operation information based on the learning data; 6. The transport system according to claim 1, further comprising a learning device having:

18. a driving command generator that generates a driving command indicating a mode of movement of each of the plurality of conveyance bodies; The operation command generator includes: a data acquisition unit that acquires operation information that is information indicating a schedule for the movement of each of the plurality of transport bodies on the transport path; an inference unit that infers the driving command by inputting the driving information to a trained model used for inferring the driving command from the driving information; 6. The transport system according to claim 1, further comprising:

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