Conveyor device

Abstract

To provide stable carrying speed control even in a section where estimation precision of a location or speed of a carried object is low for a carrier device which has a function of estimating the location of the carried object from information on a current flowing to winding of a coil.SOLUTION: The present invention relates to a carrier device which carries a carried object having a magnetic body, and comprises a plurality of coils which generate magnetic flux acting on the magnetic body, a coil drive part which applies a voltage to the plurality of coils respectively, and an arithmetic control part which has a current control part and a location estimation part, wherein the current control part determines the voltage, and the location estimation part applies voltage pulses to a coil to estimate the location of the carried object based upon current variation, and switches between a speed control mode in which the speed of the carried object is controlled and a current control mode in which the current of the coil is controlled according to a location estimation value indicative of the location of the carried object estimated by the location estimation part.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present disclosure relates to a conveying device.

Background Art

[0002] With the advancement of medical technology and the aging of society, the importance of specimen processing in clinical examinations has been increasing.

[0003] A specimen processing device for clinical examinations examines predetermined analysis items for biological samples (specimens) such as body fluids such as blood, plasma, serum, and urine. The specimen processing device can connect devices having a plurality of functions and automatically process each step. In other words, for the purpose of streamlining the operations of the laboratory, analysis units in multiple analysis fields such as biochemistry and immunology are connected by a conveying line and operated as one device.

[0004] In conventional conveying lines, the belt drive method is the mainstream. Therefore, if the conveyance stops due to some abnormality during conveyance, the specimen cannot be supplied to the devices on the downstream side.

[0005] In order to improve the processing capacity of the specimen processing device, high-speed conveyance, mass simultaneous conveyance, and conveyance in multiple directions of the specimen are desired.

[0006] Patent Document 1 discloses an electromagnetic actuator that is stationary below a conveying plane and is adapted to carry a container carrier equipped with a magnetic active device such as a permanent magnet and adapted to carry a sample container, and is adapted to move the container carrier on the conveying plane by applying a magnetic force to the container carrier. Patent Document 1 also discloses that the speed of the container carrier moving on the conveying plane is set by setting the time between consecutive activations of adjacent electromagnetic actuators. Patent Document 1 also discloses that a container carrier detection device embodied based on a reflected light barrier mainly composed of infrared rays (IR) is provided to detect the presence and position of the container carrier located on the conveying plane.

[0007] Patent Document 2 discloses that each of a plurality of electromagnetic actuators used in a laboratory sample dispensing system includes a ferromagnetic core and an exciting coil, and the exciting coil is configured to extend beyond the ferromagnetic core assigned thereto in the vertical direction. Further, Patent Document 2 discloses that a plurality of electromagnetic actuators are arranged below the transfer surface of the laboratory sample dispensing system, and a plurality of position sensors embodied as Hall sensors are distributed on the transfer surface.

[0008] Furthermore, Patent Document 3 discloses a conveying device including a first magnetic body provided on the conveyed object side, a core made of a second magnetic body, a magnetic circuit having a coil wound around the outer peripheral side of the core, a drive circuit for supplying a current to the coil of the magnetic circuit, and a conveyed object detection unit for detecting the position or speed of the magnetic body, and changing the current supplied to the coil based on the position or speed information of the magnetic body detected by the conveyed object detection unit.

[0009] Patent Document 4 discloses a conveying device in which a coil driving unit that applies a voltage to each of a plurality of coils applies a driving current to a predetermined coil based on the position of the conveyed object estimated by a position estimation unit and the path information stored in a path information storage unit, and applies a position detection current to the closest coil estimated to be closest to the conveyed object and the coils around the closest coil. Further, Patent Document 4 discloses calculating the amount of current change for each position from inductance characteristics, estimating the position of the permanent magnet at any time by sequentially calculating this amount of current change, determining whether the conveyed object has deviated from a predetermined path, and outputting a pulse voltage to a predetermined coil so as to return to the predetermined path.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Patent Document 2

[0011] In Patent Document 1, a large number of sensors (position sensors) for detecting positions such as a container carrier detection device are required, and there are concerns about cost increases and reliability degradation due to failures of the position sensors. Further, in Patent Documents 1 and 2, it is considered difficult to detect an object to be conveyed in all regions on the conveyance surface because the presence or absence of the object to be conveyed cannot be detected unless the object to be conveyed approaches the position sensor to a certain extent.

[0012] Also, in Patent Document 3, the current flowing through the winding is changed according to the position, weight, etc. of the object to be conveyed, but the method for determining the current value in a section where detection of the position, etc. is difficult is unclear. For this reason, it is considered that variations in the speed between the objects to be conveyed may occur.

[0013] In Patent Document 4, although deviation of the object to be conveyed is corrected, the adjustment of the speed of the object to be conveyed is unclear.

[0014] An object of the present disclosure is to achieve stable conveyance speed control even in a section where the estimation accuracy of the position or speed of an object to be conveyed is low in a conveyance device having a function of estimating the position of the object to be conveyed from information on the current flowing through the winding of a coil. [Means for Solving the Problems]

[0015] The conveying device of the present disclosure conveys an object to be conveyed having a magnetic body, and includes a plurality of coils that generate a magnetic flux acting on the magnetic body, a coil driving unit that applies a voltage to each of the plurality of coils, and an arithmetic control unit having a current control unit and a position estimation unit. The current control unit determines the above voltage, and the position estimation unit estimates the position of the object to be conveyed based on the current change generated by applying a voltage pulse to the coil, and switches between a speed control mode for controlling the speed of the object to be conveyed and a current control mode for controlling the current of the coil according to the position estimation value indicating the position of the object to be conveyed estimated by the position estimation unit.

Effect of the Invention

[0016] According to the present disclosure, in a conveying device having a function of estimating the position of an object to be conveyed from information on the current flowing through the winding of a coil, stable conveying speed control can be achieved even in a section where the estimation accuracy of the position or speed of the object to be conveyed is low.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8A

Figure 8B

Figure 9A

Figure 9B

Mode for Carrying Out the Invention

[0018] The present disclosure relates to a conveying device suitable for, for example, a specimen analysis system for analyzing a biological specimen (hereinafter referred to as a "specimen") such as blood or urine, and a specimen pretreatment device for performing pretreatment necessary for the analysis.

[0019] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

Example

[0020] FIG. 1 is a schematic configuration diagram showing the conveying device of the example.

[0021] In this figure, the conveying device 100 includes a permanent magnet 10, two coils 25, a coil driving unit 50 (driving circuit), a power source 55, a current detector 30, and a calculation unit 40 (calculation control unit). The permanent magnet 10 is provided on a specimen folder or the like that is an object to be conveyed. The coil 25 is composed of a cylindrical core 22 and a winding 21 provided on the outer peripheral side of the core 22. In this figure, two coils 25 are shown, but usually, two or more coils 25 are provided.

[0022] The coil driving unit 50 is connected to each coil 25. The current detector 30 detects the current flowing through the winding 21 of each coil 25 from each coil driving unit 50.

[0023] A propulsive force is generated in the permanent magnet 10 due to the interaction with the coil 25. The object to be conveyed such as the specimen folder provided with the permanent magnet 10 moves by receiving this propulsive force. As a result, a specimen container or the like (not shown) installed in the specimen folder is conveyed. The speed, moving direction, end point, etc. of the object to be conveyed are adjusted by controlling the current flowing through the coil 25.

[0024] Generally, a conveying surface (not shown) for supporting the permanent magnet 10 is provided between the coil 25 and the permanent magnet 10. The coil 25 may be configured such that a plurality of coils are arranged in a row below the conveying surface. In this case, the conveying surface may move the object to be conveyed along a linear or curved path. Also, when the conveying surface is the xy plane, the coil 25 may be configured such that a plurality of coils are arranged in columns in each of the x-axis direction and the y-axis direction below the xy plane. The permanent magnet 10 moves so as to slide on the conveying surface. Note that the container to be conveyed is not limited to a specimen container, and may be a reagent container or the like. For this reason, the container to be conveyed may be referred to as a "conveying container". In addition, the object to be conveyed includes a small device that can be conveyed.

[0025] The conveying device 100 moves the object to be conveyed between the coils 25 by passing an electric current through the winding 21 and applying an electromagnetic force to the permanent magnet 10. In order to efficiently apply the electromagnetic force and move the object to be conveyed in a desired direction, relative position information between the permanent magnet 10 and the coil 25 is required.

[0026] For example, when the permanent magnet 10 is directly above one of the two coils 25, no force in the conveying direction is generated even if an electric current is passed through the coil 25 directly below it. On the other hand, if an electric current is passed through the coil 25 adjacent to the coil 25 directly above the permanent magnet 10, a force that attracts the permanent magnet 10 to the adjacent coil 25 can be generated. That is, it is possible to efficiently generate a force and control the direction of the force.

[0027] With a configuration in which three or more coils 25 are arranged side by side, it becomes possible to arbitrarily move the object to be conveyed having the permanent magnet 10 by sequentially switching the energized coil 25 (energized coil).

[0028] In this embodiment, in order to detect the position of the permanent magnet 10 on the conveying surface, a method based on the inductance characteristics of the coil 25 is used. In this regard, it is different from the method of arranging a large number of position sensors on the conveying surface as in the prior art to detect the position of the object to be conveyed.

[0029] When using a large number of position sensors as in the prior art, position information can be obtained, but since a substrate or the like on which a new position sensor is mounted is required, it becomes a problem that it causes an increase in cost and a size increase of the device.

[0030] Hereinafter, the position detection method of the embodiment will be described.

[0031] When there is a permanent magnet 10 above the front coil 25 shown in FIG. 1, the magnetic flux generated by the permanent magnet 10 acts on the coil 25. The magnitudes of the acting magnetic fluxes are different between the front coil 25 and the rear coil 25. In other words, the magnitude of the magnetic flux acting on the coil 25 changes depending on the relative positional relationship between the permanent magnet 10 and the coil 25.

[0032] When a voltage is applied to the winding 21 by the coil driving unit 50 to flow a current, a magnetic flux generated by the current is generated in the core 22. Therefore, in the core 22, the magnetic flux by the permanent magnet 10 and the magnetic flux generated by the current flowing through the winding 21 overlap.

[0033] Generally, when a current flows through the winding 21, a magnetic field is generated around it. At this time, the generated magnetic flux is proportional to the value of the flowing current. This proportionality constant is called inductance.

[0034] However, in a circuit having a magnetic material such as the core 22, the inductance changes due to the magnetic saturation characteristics of the core 22. That is, the inductance of the winding 21 changes depending on the magnitude of the magnetic flux of the permanent magnet 10. This means that the inductance of the winding 21 changes depending on the position of the permanent magnet 10 (that is, the object to be conveyed).

[0035] Therefore, if the inductance of the winding 21 can be measured, the position of the permanent magnet 10 on the conveyance surface can be detected.

[0036] The above is the principle of the position detection method based on the inductance characteristics of the coil 25.

[0037] Next, the principle of a more specific position detection method will be described.

[0038] The voltage V generated in the winding 21 is represented by the following formula (1). That is, the voltage V is the change amount of magnetic flux per unit time.

[0039] V = -dφ / dt …(1) In the formula, φ is the magnetic flux and t is the time.

[0040] Also, when the current is I and the inductance is L, the following relational expression (2) holds.

[0041] dI / dt = (1 / L) × (dφ / dt) …(2) From the above formulas (1) and (2), the following relational expression (3) is obtained.

[0042] dI / dt = -V / L …(3) That is, when a constant voltage is applied to the winding 21, as shown in the above formula (3), the time differentiation of the current I supplied changes depending on the magnitude of the inductance L. This means that the rising manner of the current supplied when the voltage is applied is different.

[0043] Therefore, when a voltage is applied to the winding 21, the inductance L can be obtained by calculation by detecting the change amount (dI / dt) of the current generated in the winding 21. That is, if the characteristics of the inductance L of the winding 21 that change depending on the position of the permanent magnet 10 are known in advance, a voltage signal for position detection is applied, and by detecting the change amount (dI / dt) of the current generated thereby, the position of the permanent magnet 10, that is, the position of the object to be conveyed, can be obtained.

[0044] Next, the position detection method without a position sensor in the embodiment will be further described.

[0045] As shown in FIG. 1, a voltage is applied to the winding 21 by the coil driving unit 50, and the coil current flowing due to the voltage is detected by the current detector 30. Here, the coil driving unit 50 corresponds to, for example, a bidirectional chopper driven by a PWM (Pulse Width Modulation) signal. Further, the current detector 30 for detecting current includes those using a shunt resistor, a current transformer, a hall current sensor, etc., but in this embodiment, it is not particularly limited to these.

[0046] Note that the coil driving unit 50 is connected to the power supply 55, and a predetermined current is passed through the winding 21 of the coil 25 by duty-controlling this power supply voltage.

[0047] Furthermore, the arithmetic unit 40 calculates a voltage command value to be applied to the coil driving unit 50 in order to obtain the thrust required to convey the object to be conveyed, and measures the current change rate dI / dt generated in the coil 25 based on the current value detected by the current detector 30, and calculates the relative positional relationship between the coil 25 and the permanent magnet 10, and estimates the position of the permanent magnet 10 in the conveying device 1. The arithmetic unit 40 uses the estimated position information of the permanent magnet 10 to determine the timing for passing the current required for conveying the permanent magnet 10 (object to be conveyed) from the coil driving unit 50, and actually passes the current through the appropriate coil 25.

[0048] FIG. 2 is a block diagram showing the configuration of the arithmetic unit in FIG. 1.

[0049] In FIG. 2, the arithmetic unit 40 of the conveying device includes a current control unit 56, a duty setting unit 60, a current change rate arithmetic unit 61, a position estimation unit 62, an energized coil determination unit 63, and a coil switching unit 64.

[0050] The thrust command (current command flowing through the coil) and the actual coil current are input to the current control unit 56. The current control unit 56 calculates a coil voltage command value and outputs it to the duty setting unit 60. In this case, the coil voltage command value applied to the coil is calculated so that the value of the actual coil current matches the value of the current command flowing through the coil. In other words, the current control unit 56 determines the voltage applied by the coil driving unit 50.

[0051] The duty setting unit 60 determines a voltage pulse signal such as PWM and outputs it to the coil driving unit 50.

[0052] On the other hand, in order to determine which of the plurality of coils 25 to energize, the current value from the current detector 30 is used as an input, and the current change rate calculation unit 61 calculates the current change rate (dI / dt) of the coil, and the position estimator 62 estimates the position of the object to be conveyed according to the value. Further, based on the target conveyance position of the specimen and the position of the object to be conveyed described above, the energization coil determination unit 63 determines the coil to be actually energized. According to this determination, the coil switching unit 64 switches the circuit so that the desired coil 25 can be energized. Note that the control blocks described here can be realized by an arithmetic device such as a microcomputer.

[0053] In the position estimator 62, as described above, the current change rate (dI / dt), which is a value inversely proportional to the inductance L of the coil 25, is input, and the position estimated value of the object to be conveyed is calculated and output. This position estimated value is a value indicating the position of the object to be conveyed. In summary, the position estimated value is calculated based on the current change rate of a predetermined coil among the plurality of coils.

[0054] Figure 3 is a graph showing an example of how the rate of change of the current flowing through coil 25 in FIG. 1 is affected by the position of permanent magnet 10. The horizontal axis represents the position X of the object to be conveyed having permanent magnet 10, and the vertical axis represents the rate of change of current dI / dt (unit: A / s) of coil 25. X = 0 is defined with the directly upper part of coil 25 as the origin. As described above, dI / dt is inversely proportional to the inductance L, and is inversely proportional to L when coil 25 and permanent magnet 10 are regarded as integrated, in other words, L in the state where permanent magnet 10 affects coil 25.

[0055] As shown in FIG. 3, the farther permanent magnet 10 is from directly above coil 25, the smaller dI / dt becomes. Position P3 is directly above the adjacent coil 25, and position P2 is the midpoint of the line segment connecting P1 and P3. Also, at P1 and P3, the slope of dI / dt becomes smaller.

[0056] In the position estimation unit 62 of FIG. 2, for example, a characteristic table regarding the relationship between the position of the object to be conveyed (permanent magnet 10) and the rate of change of current as shown in FIG. 3 is recorded.

[0057] In this embodiment, the principle is to estimate the position of the object to be conveyed using the above-described position characteristics of the inductance. However, in the actual control logic to be processed, the rate of change of the current in the coil is used as an input. For this reason, in the position estimation unit 62, it is set as a position characteristic data table of the rate of change of current (dI / dt) as shown in FIG. 3.

[0058] Here, a method of applying a voltage necessary for detecting the position of the object to be conveyed will be described.

[0059] Figure 4 is a graph showing an example of the waveform of a voltage pulse applied to the coil to be applied.

[0060] The voltage pulse shown in this figure is a voltage signal generated by a PWM conversion method, which is a conversion method that increases or decreases the pulse width of the voltage according to the magnitude of the voltage to be applied. When this voltage is applied to coil 25, the current becomes such that a current pulsation (current change as shown by the broken line in the figure) generated by the pulse is superimposed on the average current required to generate thrust.

[0061] By generating such a current, the object to be conveyed can be conveyed, and at the same time, by measuring the current change rate at that time, the position of the object to be conveyed can also be estimated.

[0062] Figure 5 is a perspective view showing the arrangement of the coils of the conveying device.

[0063] As shown in this figure, the conveying device is composed of a plurality of coils 25. Each coil 25 has a winding 21 and a core 22. Among these coils 25, according to the conveying path of the object to be conveyed, an appropriate voltage pulse is applied to the coil 25 near the object to be conveyed to detect the position of the object to be conveyed and to convey the object to be conveyed.

[0064] From the viewpoints of improving the conveying ability of the conveying device and the large-scale conveying of specimens in the future, it is necessary to accurately control the speed of each object to be conveyed so that the speeds of the adjacent objects to be conveyed are equal and constant even when the distance between them becomes close so that they do not come into contact.

[0065] In order to realize such speed control, it is desirable to perform feedback control of the speed of the object to be conveyed.

[0066] Figure 6 is a block diagram showing an example of a configuration for implementing feedback control of the speed of the object to be conveyed.

[0067] The speed control unit 65 receives the speed command value of the object to be conveyed, which is determined according to the current sample conveyance amount. The speed calculation unit 66 receives the above-mentioned position estimated value of the object to be conveyed, and calculates the speed calculated value of the object to be conveyed. Then, the speed calculated value is input to the speed control unit 65 as a feedback value. In the speed control unit 65, a coil current command value is calculated.

[0068] The coil current command value is input to the current control unit 56. The coil current is also input to the current control unit 56. The current control unit 56 calculates and outputs a coil voltage command value using these inputs.

[0069] Here, the speed control unit 65 and the current control unit 56 can realize their functions by performing proportional-integral calculation. Also, the speed calculation unit 66 can obtain the speed calculated value of the object to be conveyed by calculating the amount of position change (dx / dt) for each predetermined time interval using the input position estimated value of the object to be conveyed.

[0070] As described above, by configuring the speed control system shown in FIG. 6, it is possible to control the conveyance speed of the object to be conveyed.

[0071] However, in this embodiment, a method of estimating the position of the object to be conveyed according to the change amount of the coil current, that is, a position sensorless method, is used without providing a position sensor for measuring the position of the object to be conveyed. Therefore, the characteristics of the speed calculated value of the object to be conveyed obtained by the speed calculation unit 66 are affected by the accuracy of the position sensorless position estimation.

[0072] The accuracy of the position estimation can be determined, for example, by the characteristics of the current change rate of the coil with respect to the position of the object to be conveyed shown in FIG. 3. As shown in FIG. 3, in particular, as the object to be conveyed moves away from the energized coil, in other words, as it approaches position P3, the value of the current change rate becomes smaller. That is, the inductance becomes larger.

[0073] Therefore, in the section near position P3, the position estimation accuracy decreases due to the influence of current detection accuracy. The calculated value of the conveyance speed of the object being conveyed (specimen conveyance speed calculated value) obtained from the time change of the position estimation value with such reduced accuracy also becomes a value including an error. When such a speed calculated value including an error is input to the speed control unit 65, the speed control accuracy also decreases. As a result, it is conceivable that it becomes difficult to convey a large amount of specimens.

[0074] Therefore, in order to solve the above problems and control the specimen conveyance speed with high accuracy, in a position section where the estimation accuracy is low, it is effective to stop the speed feedback control and directly input a coil current command to perform current control.

[0075] FIG. 7 is a block diagram showing a configuration of control for switching a control mode based on a position estimated value of an object being conveyed.

[0076] In this figure, in addition to the speed control unit 65 and the current control unit 56 shown in FIG. 6, a control mode determination unit 70 and a control mode switching unit 71 are added. All of these components are included in the arithmetic unit 40. The control mode switching unit 71 is provided between the speed control unit 65 and the current control unit 56. The control mode determination unit 70 is connected to the control mode switching unit 71.

[0077] The control mode determination unit 70 has a preset threshold value of the position estimated value.

[0078] The control mode determination unit 70 receives the energized coil information and the position estimated value. When the position estimated value is equal to or less than the threshold value (when it is farther from the energized coil), it determines that the speed calculation accuracy is low and sets it to the current control mode. In this case, it switches from the connection state shown in this figure. Here, the current control mode refers to a control mode for controlling the current of the coil (coil current).

[0079] On the other hand, when the control mode determination unit 70 determines that the position estimated value is greater than the threshold value (when close to the energized coil), it is determined that the speed calculation accuracy is high, and the speed control mode with the connection state shown in this figure is adopted. Here, the speed control mode refers to a control mode for controlling the speed of the object to be conveyed.

[0080] Specifically, in the case of the speed control mode, the coil current command value output from the speed control unit 65 is used as an input. Also, in the case of the current control mode, the coil current is arbitrarily determined and directly input to the direct current control unit 56. By doing so, even when the accuracy of the speed calculation value is low, it is possible to maintain stable conveyance speed control performance. Regarding the method for determining the coil current command value in the above current control mode, it can be arbitrarily set as long as it does not impair the performance of the specimen conveyance. For example, if the current command is set to be equal to the current value that flowed through the previous energized coil, conveyance speed control with small speed fluctuations can be continued. In summary, in the current control mode, a current command is generated based on the magnitude of the current that flowed through the previous energized coil.

[0081] Also, summarizing the above switching, the control mode determination unit 70 receives information on the energized coil among the plurality of coils and the position estimated value, makes the determination of the switching based on the accuracy of the calculated value of the speed of the object to be conveyed, and transmits the result of the determination to the control mode switching unit 71.

[0082] Next, an example of the operation by the control for switching between the speed control mode and the current control mode will be described.

[0083] FIG. 8A is a schematic diagram showing the speed control mode.

[0084] As shown in this figure, below the conveyance surface 83, coils 85, 86, and 87 are arranged from left to right in the figure. On the upper surface of the conveyance surface 83, a conveyance container 82 on which the specimen 81 is placed is movably arranged.

[0085] In this figure, the coil 86 is energized and in an excited state. The transport container 82 is moving in the section from X0 to X1 located between the two coils 85 and 86. This section is the section with high position sensitivity of the current change rate shown in FIG. 3, that is, the section where the transport speed can be calculated with high precision, and the speed control mode is suitable.

[0086] FIG. 8B is a schematic diagram showing the current control mode.

[0087] In this figure, the coil 87 is energized and in an excited state. The transport container 82 is moving in the section from the position X1 to X0 located directly above the coil 86. This section is the section with low position sensitivity of the current change rate shown in FIG. 3, that is, the section where the transport speed cannot be calculated with high precision, and the current control mode is suitable.

[0088] In this way, when the transport container 82 moves and passes through the position X1, the energized coil is switched from the coil 86 to the coil 87.

[0089] Here, an explanation will be given of how the transport speed differs when the above control mode switching, that is, switching between the speed control mode and the current control mode, is performed and when it is not performed.

[0090] FIG. 9A is a graph showing the transport speed of the comparative example. The horizontal axis represents the position X, and the vertical axis represents the transport speed v.

[0091] In this figure, since the control mode is not switched, the accuracy of the transport speed is low in the section from X1 to X0 where the position sensitivity of the current change rate is low. For this reason, the actual transport speed (shown by the solid line curve) deviates from the speed command value vd (shown by the broken line). In other words, in this section, the difference between the actual transport speed and the speed command value vd becomes large.

[0092] On the other hand, FIG. 9B is a graph showing the transport speed of the embodiment. The horizontal axis represents the position X, and the vertical axis represents the transport speed v.

[0093] In this figure, the control mode is switched. In this case, in the section from X1 to X0 where the positional sensitivity of the current change rate is low, since driving is continued using the current command in the previous section from X0 to X1, the deviation from the speed command value of the actual conveyance speed is suppressed.

[0094] As described above, in a conveyance device that performs position estimation without a position sensor using the value of the coil current, by switching the control mode according to the position of the object to be conveyed during conveyance, the conveyance speed control can be made highly accurate.

Explanation of Signs

[0095] 10: Permanent magnet, 21: Coil, 22: Core, 25: Coil, 30: Current detector, 40: Arithmetic unit, 50: Coil drive unit, 55: Power supply, 56: Current control unit, 60: Duty setting unit, 61: Current change rate arithmetic unit, 62: Position estimation unit, 63: Energized coil determination unit, 64: Coil switching unit, 65: Speed control unit, 66: Speed arithmetic unit, 70: Control mode determination unit, 71: Control mode switching unit, 81: Specimen, 82: Conveyance container, 83: Conveyance surface, 85, 86, 87: Coils, 100: Conveyance device.

Claims

1. A conveying device for conveying an object to be conveyed having a magnetic body, comprising: a plurality of coils that generate magnetic fluxes acting on the magnetic body; a coil driving unit that applies a voltage to each of the plurality of coils; an arithmetic control unit having a current control unit and a position estimation unit, wherein the current control unit determines the voltage, the position estimation unit estimates the position of the object to be conveyed based on a current change generated by applying a voltage pulse to the coil, and switches between a speed control mode for controlling the speed of the object to be conveyed and a current control mode for controlling the current of the coil according to a position estimation value indicating the position of the object to be conveyed estimated by the position estimation unit.

2. The conveying device according to claim 1, wherein in the current control mode, a current command is generated based on the magnitude of the current flowing through the previously energized coil.

3. The conveying device according to claim 1, wherein the position estimation value is calculated based on a current change rate of a predetermined coil among the plurality of coils.

4. The arithmetic control unit further includes a control mode determination unit and a control mode switching unit, wherein the control mode determination unit receives information on the energized coils among the plurality of coils and the position estimation value, makes a determination of the switching based on the accuracy of the calculated value of the speed of the object to be conveyed, and transmits the result of the determination to the control mode switching unit.

Images