Patent Application
20230038090
The present application claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2021-123752, filed Jul. 28, 2021. The contents of this application are incorporated herein by reference in their entirety.
Embodiments of the disclosure relate to a linear transport system and a method for controlling the linear transport system.
International Patent Publication No. WO 2018/055772 discloses a linear conveyor device for moving a slider along a guide rail in a predetermined moving direction. In this linear conveyor device, each driver in each of the plurality of sensor structures has a data storage unit, a sensor position calculation unit, and a position specifying unit. The data storage unit stores, as first sensor interval data, the interval between the sensor of the sensor structure to which it belongs and the sensor of the sensor structure located upstream in the slider movement direction. The sensor position calculation unit calculates sensor position data of a sensor constituting a sensor structure to which it belongs based on first sensor interval data stored in a data storage unit. The position specifying unit specifies the position of the slider based on the addition data obtained by adding the sensor position data from the sensor position calculation unit and the detection data from the sensor constituting the sensor structure to which the position specifying unit belongs.
According to one aspect of the present invention, a linear transport system includes a stator having a track, a plurality of carriers movable along the track, a plurality of scales provided on the plurality of carriers, respectively, a plurality of sensors provided along the track of the stator at respective intervals, a parameter memory, and position calculation circuitry. The stator includes a plurality of coils provided along the track. Each of the plurality of carriers has a magnet. The plurality of sensors is configured to detect the plurality of carriers to obtain scale positions of the plurality of scales. The parameter memory is configured to memorize first cumulative values each corresponding to a corresponding sensor among the plurality of sensors. Each of the first cumulative values is obtained by accumulating, from a reference position to the corresponding sensor, error correction values based on which errors between the respective intervals and measured values of the respective intervals are corrected. The position calculation circuitry is configured to calculate a position of a detected carrier among the plurality of carriers based on detection data of a detecting sensor among the plurality of sensors that has detected the detected carrier and based on the first cumulative value corresponding to the detecting sensor.
According to another aspect of the present invention, a linear transport system includes a stator having a track, a plurality of carriers movable along the track, a plurality of scales provided on the plurality of carriers, respectively, a plurality of sensors provided along the track of the stator at respective intervals, a plurality of first control circuitry, and second control circuitry connected to the plurality of first control circuitry to control positions of the plurality of carriers. The stator includes a plurality of coils provided along the track. Each of the plurality of carriers has a magnet. The plurality of sensors is configured to detect the plurality of carriers to obtain scale positions of the plurality of scales. Each of the plurality of first control circuitry is configured to control group coils among the plurality of coils which are provided in a partial region of the track of the stator. The second control circuitry includes collision prevention processing circuitry to prevent a collision by monitoring a distance between the plurality of carriers based on detection data of the plurality of sensors. Each of the plurality of first control circuitry has emergency stop processing circuitry configured to determine whether two or more of the plurality of carriers exist within the respective intervals based on the detection data of the plurality of sensors, and configured to stop the plurality of carriers when it is determined that the two or more carriers exist within the respective intervals.
According to the other aspect of the present invention, a method for controlling a linear transport system includes providing a stator which includes a track and a plurality of coils provided along the track; providing a plurality of carriers movable along the track, each of the plurality of carriers having a magnet; providing a plurality of scales on the plurality of carriers, respectively; providing a plurality of sensors along the track of the stator at respective intervals, the plurality of sensors detecting the plurality of carriers to obtain scale positions of the plurality of scales; accumulating, from a reference position to a corresponding sensor among the plurality of sensors, to obtain first cumulative values, error correction values based on which errors between the respective intervals and measured values of the respective intervals are corrected; memorizing the first cumulative values each corresponding to the corresponding sensor; and calculating a position of a detected carrier among the plurality of carriers based on detection data of a detecting sensor among the plurality of sensors that has detected the detected carrier and based on the first cumulative value corresponding to the detecting sensor.
According to further aspect of the present invention, a method for controlling a linear transport system includes providing a stator which includes a track and a plurality of coils provided along the track; providing a plurality of carriers movable along the track, each of the plurality of carriers having a magnet; providing a plurality of scales on the plurality of carriers, respectively; providing a plurality of sensors along the track of the stator at respective intervals, the plurality of sensors detecting the plurality of carriers to obtain scale positions of the plurality of scales; providing a plurality of first control circuitry each of which is configured to control group coils among the plurality of coils which are provided in a partial region of the track of the stator; determining, by the plurality of first control circuitry, whether two or more of the plurality of carriers exist within the respective intervals based on the detection data of the plurality of sensors; stopping the plurality of carriers when the plurality of first control circuitry determine that the two or more carriers exist within the respective intervals; providing second control circuitry connected to the plurality of first control circuitry to control positions of the plurality of carriers; and preventing a collision, by the second control circuitry, by monitoring a distance between the plurality of carriers based on detection data of the plurality of sensors.
A more complete appreciation of the present disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings.
Hereinafter, embodiments will be described with reference to the drawings.
<1. Overall Configuration of Linear Transport System>
Referring to
As shown in
As shown in
The multi-axis amplifier 11 (an example of “first control circuitry”) controls the energization of the coils in a part of the section of the stator 3. In the example shown in
As shown in
The linear controller 13 (an example of second control circuitry) is connected to a plurality of multi-axis amplifiers 11 corresponding to the common stator 3 via a communication cable 19. The linear controller 13 controls the positions of a plurality of movable elements 5 located on the loop of the stator 3. The linear transport system 1 has a plurality of linear controllers 13. The linear controller 13 converts the position command for designating the position of each movable element 5 on the loop in the stator 3 received from the operation controller 15 into a position command for each section of the stator 3 corresponding to each multi-axis amplifier 11, and transmits the position command to each multi-axis amplifier 11. The linear controller 13 generates a speed command for preventing a collision between the movable elements 5 on the loop of the stator 3, and transmits it to each multi-axis amplifier 11.
The operation controller 15 is connected to a plurality of linear controllers 13 via a communication cable 19. The operation controller 15 controls the positions of the plurality of movable elements 5 located on the loop of the stator 3, that is, the positions of all the movable elements 5 provided in the linear transport system 1. The operation controller 15 transmits a position command for designating the position of each movable element 5 on the loop in the stator 3 to each linear controller 13.
The linear controller 13 and the operation controller 15 are a control apparatus having, for example, a calculation device (CPU), a recording device, an input device and the like. As the linear controller 13 and the operation controller 15, for example, a general-purpose computer (PC), a motion controller, a programmable logic controller (PLC) or the like may be used.
The configuration of the linear transport system 1 described above is an example, and is not limited to the contents described above. For example, the stator 3 may be disposed horizontally or inclined at a predetermined angle with respect to the vertical or horizontal direction. The number of the stators 3 is not limited to a single one, but may be a plurality. The object to which power is supplied by the multi-axis amplifier 11 is not limited to three sets of coils 17, and power may be supplied to two sets or four or more sets of coils 17. It may be a single axis amplifier that supplies power to a set of coils 17.
<2. Functional Configuration of Control Unit of Multi-Axis Amplifier>
An example of the functional configuration of the control unit of the multi-axis amplifier 11 will be described with reference to
As shown in
The parameter recording unit 27 records an error correction value for correcting an error between a set value of an installation interval (an example of “respective intervals”) of the sensor head 25 and a measured value obtained by measuring the installation interval in advance, and a first cumulative value accumulated from the sensor head 25 set at the origin (an example of “a reference position”) as a parameter for each sensor head 25. The error correction value may be an error value obtained by subtracting the set value from the measured value, or may be a measured value itself in which the error value is incorporated. The first cumulative value may be a cumulative error value obtained by accumulating error values or a cumulative measurement value obtained by accumulating measurement values.
The installation interval of the sensor head 25 may be measured, for example, by moving the measuring movable element 5 having a scale 23 longer than the installation interval along the stator 3. In this case, the difference between the detection data of the adjacent sensor heads becomes a measurement value of the installation interval.
The parameter recording unit 27 records the second cumulative value accumulated from the sensor head 25 whose origin is set to the set value of the installation interval of the sensor head 25 as a separate parameter for each sensor head 25.
The parameter recording unit 27 records the origin correction value, which is the detection data of the sensor head 25 that has detected the scale 23 of the movable element 5, as a parameter common to a plurality of sensor heads 25 disposed on the same stator 3, when the movable element 5 is located at a desired position as the origin.
The parameter recording unit 27 may record the parameters (first cumulative value, second cumulative value, origin correction value) for the three sensor heads 25 connected to the multi-axis amplifier 11 to which the parameter recording unit 27 belongs, or may record the parameters for all the sensor heads 25 arranged in the common stator 3. As the parameter recording unit 27, a nonvolatile memory such as an EEPROM or a recording device such as a hard disk may be used. The parameter recording unit 27 may be provided outside the multi-axis amplifier 11, for example, in a linear controller 13, an operation controller 15, a sensor head 25, or other external recording devices and the like. In this case, the multi-axis amplifier 11 may obtain necessary information from a parameter recording unit 27 provided outside.
A position calculation unit 29 calculates the machine coordinate position of a movable element 5 on the basis of detection data of a sensor head 25 which has detected a scale 23, a first cumulative value and a second cumulative value which are parameters set for the sensor head 25 which has detected the scale 23, and an origin correction value which is a parameter common to a plurality of sensor heads 25. Details of the calculation method will be described later.
An emergency stop processing unit 31 determines whether or not two or more movable elements 5 exist within a predetermined interval of a stator 3 on the basis of the machine coordinate position of the movable element 5 calculated by a position calculation unit 29, and stop emergently all or a part of the two or more movable elements 5 (for example, the rear movable element 5) when it is determined that two or more movable elements 5 exist. The predetermined interval is a coil pitch of a pair of coils 17 including, for example, a U-phase coil 17U, a V-phase coil 17V, and a W-phase coil 17W. As described above, the multi-axis amplifier 11 performs energization control for each pair of coils 17 to control the position of the movable element 5. Therefore, when two or more movable elements 5 are present in the coil pitch of one set of coils 17, each of them cannot be controlled independently, and there is a possibility that the movable element 5 becomes uncontrollable and a collision or the like is caused. In order to control each movable element 5 independently, it is necessary to make the interval between each movable element 5 larger than the coil pitch of one set of coils 17. When two or more movable elements 5 are present in the coil pitch of one set of coils 17, collision can be avoided by making an emergency stop, and reliability can be ensured.
The processes in the parameter recording unit 27, the position calculation unit 29, the emergency stop processing unit 31, the motor control unit 33 and the like described above are not limited to examples of sharing of these processes. For example, the processing may be performed by a smaller number of processing units (for example, one processing unit), or may be performed by further subdivided processing units. In the multi-axis amplifier 11, only a portion for supplying electric power to the coil 17 (for example, an inverter portion, a PWM control circuit or the like) may be mounted by an actual device, and other functions of each of the above-mentioned processing portions may be mounted by a program executed by the CPU901 (see
<3. Specific Example of Calculation Method for Each Parameter of Sensor Head and Machine Coordinate Position of Movable Element>
With reference to
In the example shown in
In this case, the sensor head acquisition position (an example of detection data) by the sensor head 25B with respect to the scale 23 of the movable element 5 located at the origin becomes 100 pulses, and the origin offset (an example of origin correction value) becomes 100 pulses. The origin offset is recorded as a parameter common to all the sensor heads 25 arranged in the common stator 3.
The sensor interval offset (an example of the second cumulative value) obtained by accumulating the set value of the installation interval of each sensor head 25 from the sensor head 25B set at the origin is recorded as a separate parameter for each sensor head 25. The sensor interval offset is, for example, 0 pulses in the sensor head 25B, 2000 pulses in the sensor head 25C, 4000 pulses in the sensor head 25D, and 2998000 pulses in the sensor head 25A.
(Equation 1)
Mechanical coordinate position [pls] of movable element=sensor head acquisition position [pls]+sensor interval offset [pls]−origin offset [pls] (1)
According to the above equation (1), the machine coordinate position of the movable element 5 becomes 0 pulses when calculated using the sensor head acquisition position by the sensor head 25B, and becomes 3000000 pulses (=0 pulses) when calculated using the sensor head acquisition position by the sensor head 25A. The mechanical coordinate position of the movable element 5 is the origin position regardless of which detection data of the sensor heads 25A and 25B is used.
In this case, an error value (an example of the error correction value) obtained by subtracting the set value from the measured value obtained by measuring the installation interval between the sensor heads 25 in advance, and a sensor interval error correction cumulative value (an example of the first cumulative value) accumulated from the sensor head 25B set at the origin are recorded as separate parameters for each sensor head 25. The sensor interval error correction cumulative value is, for example, 0 pulses for the sensor head 25B, 300 pulses for the sensor head 25C, and 400 pulses for the sensor head 25D. The origin offset and sensor interval offset are the same as those shown in
In the example shown in
(Equation 2)
Machine coordinate position [pls] of movable element=sensor head acquisition position [pls]+sensor interval error correction cumulative value [pls]+sensor interval offset [pls]−origin offset [pls] (2)
According to the above equation (2), the machine coordinate position of the movable element 5 becomes 4400 pulses even when calculated using the sensor head acquisition position by the sensor head 25D, and becomes 4400 pulses even when calculated using the sensor head acquisition position by the sensor head 25C.
In the example shown in
(Equation 3)
Mechanical coordinate position [pls] of movable element=sensor head acquisition position [pls]+sensor interval error corrected offset [pls]−origin offset [pls] (3)
According to the above equation (3), the machine coordinate position of the movable element 5 becomes 4400 pulses even when calculated using the sensor head acquisition position by the sensor head 25D, and becomes 4400 pulses even when calculated using the sensor head acquisition position by the sensor head 25C.
In the above description, the machine coordinate position of the movable element is calculated by the number of pulses generated by the sensor head 25, but other units may be used. For example, it may be calculated using a predetermined command unit (for example, 1 command unit=1 mm).
As described above, each cumulative value is accumulated from the sensor head 25B set to the origin, but may be a value accumulated from the origin in the machine coordinates. In this case, for example, the sensor interval offset (an example of the second cumulative value) may be 2999900 pulses for the sensor head 25B, 1900 pulses for the sensor head 25C, 3900 pulses for the sensor head 25D, or 2997900 pulses for the sensor head 25A. For example, the sensor interval error correction cumulative value (an example of the first cumulative value) shown in
<4. Processing Procedure of Multi-Axis Amplifier>
An example of a processing procedure executed by the multi-axis amplifier 11 will be described with reference to
In step S10, the multi-axis amplifier 11 acquires parameters of each sensor head 25 from the parameter recording unit 27. The parameters of the sensor head 25 include a sensor interval offset, an origin offset, and a sensor interval error correction cumulative value.
In step S20, the multi-axis amplifier 11 determines whether or not the connected sensor head 25 has detected the scale 23. If the scale 23 is not detected (step S20: NO), this step S20 is repeated until the scale 23 is detected. When the scale 23 is detected (step S20: YES), the process proceeds to step S30.
In step S30, the multi-axis amplifier 11 acquires the detection data from the sensor head 25 that has detected the scale 23. The detection data includes the movable element ID and the sensor head acquisition position.
In step S40, the multi-axis amplifier 11 calculates the machine coordinate position of the movable element 5 by the position calculation unit 29 based on the sensor head acquisition position acquired in step S30 and the parameter acquired in step S10. In steps S10 to S40, parameters such as cumulative data are acquired before the scale 23 is detected, and only sensor head acquisition position data is acquired when the scale 23 is detected, so that the machine coordinate position can be calculated quickly.
In step S50, the multi-axis amplifier 11 performs position control or speed control of the movable element 5 by energizing the coil 17 based on the position command received from the linear controller 13 and the machine coordinate position of the movable element 5 calculated in step S40 by the motor control unit 33.
In step S60, the multi-axis amplifier 11 determines whether or not the detection of the scale 23 by the sensor head 25 has been completed. When the scale 23 is being detected (step S60: NO), the process returns to step S30. The procedure of steps S30 to S50 is repeated until the detection of the scale 23 is completed. When the detection of the scale 23 is completed (step S60: YES), the process returns to step S20.
Note that the above-described processing procedure is an example, and at least a part of the above-described procedure may be deleted or changed, or a procedure other than the above-described procedure may be added. Further, the order of at least a part of the procedure may be changed, or a plurality of procedures may be combined into a single procedure.
<5. Functional Configuration of Linear Controller>
An example of a functional configuration of the linear controller 13 will be described with reference to
As shown in
A distance determination unit 43 determines whether or not an actual distance between movable elements (an example of the distance between movable elements), which is the actual movable distance between a rear movable element 5R (an example of “a first movable element”) located at the rear and a front movable element (5F) (an example of a second movable element) located at the front in the moving direction of a plurality of movable elements 5, is equal to or less than a predetermined traveling distance of the movable element (an example of a threshold value). The traveling distance between the movable elements is, for example, a sum of the set value of the distance between the movable elements, which is a value set in advance as the distance between the movable elements, and the deceleration distance of the rear movable element 5R, which is a braking distance required until the rear movable element 5R stops. The set value of the distance between movable elements varies according to the interval. For example, in front of the curve section, the set value of the distance between the movable elements may be increased more than in the straight section.
It should be noted that the travel distance between the movable elements is not limited to the sum of the set value of the distance between the movable elements and the deceleration distance of the rear movable element 5R. For example, the travel distance between the movable elements may be the sum of the set value of the distance between the movable elements and the relative distance required until the rear movable element 5R decelerates to the speed of the front movable element 5F. The travel distance between the movable elements may be the sum of the set value of the distance between the movable elements, the deceleration distance of the rear movable element, and the relative distance required for the rear movable element 5R to decelerate to the speed of the front movable element 5F.
The acceleration/deceleration control unit 45 decelerates the speed of the rear movable element 5R so as to be substantially equal to the speed of the front movable element 5F when it is determined by the distance determination unit 43 that the actual distance between the movable elements is equal to or less than the distance between the movable elements during travel. When the speed of the rear movable element 5R is decelerated so as to be substantially equal to the speed of the front movable element 5F, the acceleration/deceleration control unit 45 executes additional deceleration on the basis of a difference value obtained by subtracting the actual distance between the movable elements from the distance between the movable elements during travel. The additional deceleration makes it possible to increase the actual distance between the movable elements, and an appropriate distance between the movable elements can be maintained by performing the additional deceleration until the actual distance between the movable elements is greater than the distance between the movable elements during travel. The difference value is an amount of representing how closely approached the distance between the rear movable element 5R and the front movable element 5F is and become shorter than the distance between the movable elements during travel. The additional deceleration is executed so that the smaller the actual distance between the movable elements after the approach (the larger the approach amount), the larger the deceleration amount. For example, when the distance between the movable elements during travel is 100 mm, additional deceleration may be executed in proportion to the approaching distance, such as +1% deceleration of the rear movable element 5R when the distance between the actual movable elements is 99 mm (when the approaching distance is 1 mm), +10% deceleration of the rear movable element 5R when the distance between the actual movable elements is 90 mm (when the approaching distance is 10 mm), and +90% deceleration of the rear movable element 5R when the distance between the actual movable elements is 10 mm (when the approaching distance is 90 mm)
When the speed of the rear movable element 5R is decelerated so as to be substantially equal to the speed of the front movable element 5F, a speed determination unit 47 determines whether or not the speed of the front movable element 5F is greater than the command speed of the rear movable element 5R. The command speed of the rear movable element 5R is a command speed based on a speed profile based on a position command for the rear movable element 5R. The acceleration/deceleration control unit 45 controls the speed of the rear movable element 5R so as to follow the command speed when the speed determination unit 47 determines that the speed of the front movable element 5F is greater than the command speed of the rear movable element 5R.
The processes in the collision prevention processing unit 41, the distance determination unit 43, the acceleration/deceleration control unit 45, the speed determination unit 47 and the like described above are not limited to examples of the sharing of these processes. For example, the processing may be performed by a smaller number of processing units (for example, one processing unit), or may be performed by further subdivided processing units. The functions of each processing unit may be implemented by a program executed by the CPU901 (see
<6. Processing Procedure of Linear Controller 13>
An example of a processing procedure executed by the linear controller 13 will be described with reference to
In step 110, the linear controller 13 controls the position or speed of the movable element 5 so as to follow the speed profile based on the position command received from the operation controller 15.
In step 120, the linear controller 13 determines whether or not the actual distance between the movable element 5 (hereinafter referred to as “rear movable element 5R”) to be processed and the front movable element 5F located in front of the movable element 5F is equal to or less than the distance between the movable elements during travel by the distance determination unit 43. If the actual distance between the movable elements is greater than the distance between the movable elements during travel (step S120: NO), the process returns to step S110. When the actual distance between the movable elements is equal to or less than the distance between the movable elements during travel (step S120: YES), the process proceeds to step S130.
In step S130, the linear controller 13 reduces the speed of the rear movable element 5R by the acceleration/deceleration control unit 45 so as to be substantially equal to the speed of the front movable element 5F. Further, when the speed of the rear movable element 5R is substantially equal to the speed of the front movable element 5F, the linear controller 13 executes an additional deceleration by the acceleration/deceleration control unit 45 in proportion to a difference value (approach amount) obtained by subtracting the actual distance between the movable elements from the distance between the movable elements during travel.
In step 140, the linear controller 13 determines whether or not the speed of the front movable element 5F is equal to or less than the command speed based on the speed profile of the rear movable element 5R by the speed determination unit 47. When the speed of the front movable element 5F is higher than the command speed of the rear movable element 5R (step S140: NO), the process returns to the previous step S110 to control the position or speed of the rear movable element 5R so as to follow the speed profile. When the speed of the front movable element 5F is equal to or lower than the command speed of the rear movable element 5R (step S140: YES), the process proceeds to step S150.
In step S150, the linear controller 13 determines whether or not the distance between the rear movable element 5R and the front movable element 5F between the actual movable elements 5 is greater than the distance between the traveling movable elements 5 by the distance 43. When the actual distance between the movable elements is equal to or less than the distance between the movable elements during travel (step S150: NO), the process returns to step S130 to continue the deceleration. If the actual distance between the movable elements is greater than the distance between the movable elements during travel (step S150: YES), the process proceeds to step S160.
In step 160, the linear controller 13 terminates the deceleration with respect to the rear movable element 5R by the acceleration/deceleration control unit 45. Thereafter, the process returns to step 120.
Note that the above-described processing procedure is an example, and at least a part of the above-described procedure may be deleted or changed, or a procedure other than the above-described procedure may be added. Further, the order of at least a part of the procedure may be changed, or a plurality of procedures may be combined into a single procedure.
<7. Specific Example of Operation of Movable Element by Collision Prevention Processing Unit of Linear Controller>
With reference to
As shown in
As shown in
As shown in
As shown in
As shown in
As shown in
As shown in
As shown in
As shown in
<8. Effects of Embodiment>
As described above, the linear transport system 1 of the present embodiment includes a stator 3 having a plurality of coils 17, a plurality of movable elements 5 having magnets 21 and moving along the stator 3 to convey a workpiece, a scale 23 provided on the movable elements 5, a plurality of sensor heads 25 arranged along the stator 3 at a predetermined installation interval to detect the scale 23, a parameter recording unit 27 which records a sensor interval error correction cumulative value or a sensor interval error-corrected offset accumulated from the sensor head 25 whose origin is set to an error value for correcting an error between the set value of the installation interval and a measured value, or a measured value, as a parameter for each sensor head 25, and a position calculation unit 29 which calculates a machine coordinate position of the movable elements 5 based on the detection data of the sensor head 25 having detected the scale 23 and the accumulated sensor interval error correction value or the sensor interval error-corrected offset set in the sensor head 25 having detected the scale 23.
In the linear transport system 1 of the present embodiment, the movable element 5 moves along the stator 3 to convey the workpiece. A plurality of sensor heads 25 arranged along the stator 3 at predetermined intervals detect a scale 23 provided on the movable element 5. In the parameter recording unit 27, an error value for correcting an error between a set value of an installation interval between sensor heads 25 and a previously measured value, or a sensor interval error correction cumulative value or a sensor interval error correction offset accumulated from the sensor head 25 with the measured value set as an origin, are recorded as separate parameters for each sensor head 25. The position calculation unit 29 calculates the machine coordinate position of the movable element 5 on the basis of the detection data of the sensor head 25 which has detected the scale 23 and the sensor interval error correction cumulative value or the sensor interval error correction offset set for the sensor head 25 which has detected the scale 23. In this way, the mechanical coordinate position of the movable element 5 can be calculated using only the detection data of the sensor head 25 that has detected the scale 23 and the parameters set for the sensor head 25. Since the processing for reading out the parameters of the other sensor head 25 or the like is unnecessary, the processing speed is increased, and the machine coordinate position of the movable element 5 can be calculated quickly. Therefore, the reliability of the linear transport system 1 can be improved. When any one of the sensor heads 25 is replaced, the sensor heads 25 other than the replaced sensor head 25 do not change because the parameter related to the error is a cumulative value. Therefore, only the parameters relating to the replaced sensor head 25 may be reset, and the installation interval measurement work and parameter setting work at the time of sensor replacement can be facilitated.
In the present embodiment, the sensor interval error correction cumulative value may be a value accumulated from the sensor head 25 whose origin is the error value between the set value of the installation interval and the measured value, the parameter recording unit 27 may record the sensor interval offset accumulated from the sensor head 25 whose origin is the set value of the installation interval as a separate parameter for each sensor head 25, and the position calculation unit 29 may calculate the machine coordinate position of the movable element 5 based on the detection data of the sensor head 25 which detected the scale 23, and the sensor interval error correction cumulative value and the sensor interval offset set in the sensor head 25 which detected the scale 23.
In this case, the cumulative value of the set value of the installation interval and the cumulative value of the error value of the installation interval are recorded as separate parameters for each sensor head 25. As a result, the magnitude of the accumulated error value in each sensor head 25 becomes clear, and the error value can be easily controlled.
In the present embodiment, the parameter recording unit 27 may record the origin offset, which is the detection data of the sensor head 25 that detected the scale 23 of the movable element 5, as a parameter common to a plurality of sensor heads 25 when the movable element 5 is located at a position to be the origin, and the position calculation unit 29 may calculate the machine coordinate position of the movable element 5 based on the detection data of the sensor head 25 that detected the scale 23, the accumulated sensor interval error correction value set for the sensor head 25 that detected the scale 23, and the origin offset.
In this case, an arbitrary position on the stator 3 can be set as the origin, and the machine coordinate position of the movable element 5 can be calculated with the origin as a reference. Therefore, the degree of freedom in setting the machine coordinates is increased, and the convenience of the user can be improved. Further, since the origin offset can be set as a parameter common to each sensor head 25, the parameter setting operation is facilitated.
In this embodiment, the linear transport system 1 may further comprise a multi-axis amplifier 11 for controlling the energization of a coil 17 in a part section of a stator 3, and a linear controller 13 connected to the multi-axis amplifiers 11 for managing the machine coordinate positions of the plurality of movable elements 5, in which case the linear controller 13 may comprise a collision prevention processing unit 41 for preventing a collision by monitoring the distance between the plurality of movable elements 5 on the basis of the machine coordinate position of the, movable element 5 calculated by the position calculation unit 29 of the multi-axis amplifier 11, and the multi-axis amplifier 11 may comprise an emergency stop processing unit 31 for determining whether two or more movable elements 5 are present in a predetermined section of the stator 3 on the basis of the machine coordinate position of the movable element 5 calculated by the position calculation unit 29 and for urgently stopping the movable element 5 when it is determined that two or more movable elements 5 are present.
In this case, the linear transport system 1 can be provided with a two stage collision prevention function by two control methods, and a linear transport system 1 having a high collision prevention function can be realized. Further, by adopting a system in which the machine coordinate position of the movable element 5 is calculated by the multi-axis amplifier 11 having a processing speed higher than that of the linear controller 13, and the upper linear controller 13 performs collision prevention by utilizing the position of the movable element 5, collision prevention processing for the entire movable element 5 using the position of the movable element 5 with high accuracy becomes possible, and reliability can be improved.
In this embodiment, the collision prevention processing unit 41 may have a distance determination unit 43 for determining whether or not the actual distance between the rear movable element 5R positioned rearward in the moving direction of the plurality of movable elements 5 and the front movable element 5F positioned forward in the moving direction of the plurality of movable elements 5 is equal to or less than the distance between the movable elements 5 during travel, and an acceleration/deceleration control unit 45 for decelerating the speed of the rear movable element 5R so as to be equal to the speed of the front movable element 5F when the distance between the real movable elements 5 is determined by the distance determination unit 43 to be equal to or less than the distance between the movable elements 5 during travel.
In this case, it is possible to prevent the collision of front movable element 5F without stopping the rear movable element 5R. As a result, the linear transport system 1 can be realized which can prevent the collision of each movable element 5 while suppressing the increase in the tact time of the workpiece conveying.
In this embodiment, the travel distance between the movable elements 5 may be the sum of the set value of the distance between the movable elements 5 set in advance as the distance between the movable elements 5 and the deceleration distance of the rear movable element 5R required until the rear movable element 5R stops.
In this case, the distance between the movable elements during travel can be set to the sum of the set value of the distance between the movable elements and the braking distance of the rear movable element 5R. As a result, for example, when the front movable element 5F suddenly stops, the distance between the actual movable elements becomes within a predetermined distance, and even when the rear movable element 5R is stopped, the distance between the actual movable elements can be maintained at a set value of minutes. Therefore, the effectiveness of the collision prevention function can be enhanced.
In the present embodiment, when the speed of the rear movable element 5R is decelerated so as to be equal to the speed of the front movable element 5F, the acceleration/deceleration control unit 45 may perform additional deceleration on the basis of the difference value obtained by subtracting the distance between the real movable elements from the distance between the traveling movable elements.
In this case, it is possible to calculate how close the distance between the rear movable element 5R and the front movable element 5F is to the distance between the traveling movable elements 5 (i.e., approach amount). Then, by performing additional deceleration based on the approach amount, it is possible to perform additional deceleration that is larger as the distance between the actual movable elements after the approach is smaller (as the approach amount is larger). Thus, the reliability of the collision prevention function can be further improved.
In this embodiment, the collision prevention processing unit 41 may have a speed determination unit 47 for determining whether or not the speed of the front movable element 5F is greater than the command speed of the rear movable element 5R when the speed of the rear movable element 5R is decelerated to be equal to the speed of the front movable element 5F, and in this case, the acceleration/deceleration control unit 45 may control the speed of the rear movable element 5R so as to follow the command speed when the speed determination unit 47 determines that the speed of the front movable element 5F is greater than the command speed of the rear movable element 5R.
When the speed of the front movable element 5F is higher than the command speed of the rear movable element 5R, no collision occurs even if the rear movable element 5R is made to follow the command speed . Therefore, in such a case, by making the rear movable element 5R follow the command speed, it is possible to operate the rear movable element 5R according to the speed profile based on the position command while avoiding collision with the front movable element 5F.
<9. Hardware Configuration Example of Multi-Axis Amplifier or Linear Controller>
With reference to
As shown in
The program can be recorded in, for example, a ROM903, a RAM905, a recording device 917 using a hard disk, or the like.
The program can also be recorded temporarily or non-temporarily (permanently) on a removable recording medium 925 such as a magnetic disk such as a flexible disk, an optical disk such as a CD, MO disk or DVD, or a semiconductor memory. Such a recording medium 925 can be provided as so-called package software. In this case, the program recorded on the recording medium 925 may be read by the drive 919 and recorded on the recording device 917 via the input/output interface 911, the bus 909, or the like.
The program may be recorded in a download site, another computer, another recording device, or the like (not shown). In this case, the program is transferred via a network NW such as a LAN or the Internet, and the communication device 923 receives the program. The program received by the communication device 923 may be recorded in the recording device 917 via the input/output interface 911, the bus 909, or the like.
The program may also be recorded in an appropriate external connection device 927, for example. In this case, the program may be transferred via an appropriate connection port 921 and recorded in the recording device 917 via an input/output interface 911, a bus 909, or the like.
Then, the CPU901 executes various processes according to the program recorded in the recording device 917, thereby realizing processes by the parameter recording unit 27, the position calculation unit 29, the emergency stop processing unit 31, the motor control unit 33, and the like. At this time, for example, the CPU901 may directly read a program from the recording device 917 and execute the program, or may temporarily load the program into the RAM905 and execute the program. Further, when the CPU901 receives a program via, for example, the communication device 923, the drive 919, or the connection port 921, it may directly execute the received program without recording it in the recording device 917.
Further, the CPU901 may perform various processes based on signals or information input from an input device 913 such as a mouse, keyboard, microphone (not shown), for example, as needed.
Then, the CPU901 may output the result of executing the above-described processing from an output device 915 such as a display device or an audio output device, and the CPU901 may transmit the processing result via the communication device 923 or the connection port 921 if necessary, and may record the processing result in the recording device 917 or the recording medium 925.
It should be noted that in the above description, when “vertical”, “parallel”, “plane” or the like is described, the description does not have a strict meaning. That is, the terms “vertical”, “parallel”, and “plane” mean “substantially vertical”, “substantially parallel”, and “substantially plane” in which design and manufacturing tolerances and errors are allowed.
Further, in the above description, when there are descriptions such as “same”, “similar”, “equal”, and “different” in external dimensions, sizes, shapes, and positions, the descriptions do not have a strict meaning. In other words, the terms “same”, “similar”, “equal” and “different” mean “substantially same”, “substantially similar”, “substantially equal” and “substantially different”, respectively, in which tolerances and errors in design and manufacturing are allowed.
However, when a threshold value (see the flow chart of
In addition to the above-described methods, methods according to the above-described embodiments or modifications may be used in combination. In addition, although each example is not given, the above-described embodiments and each modification are implemented with various modifications within a range not departing from the spirit thereof.
Further, the problems and effects to be solved by the above-described embodiments, modifications and the like are not limited to the above-described contents. That is, according to embodiments, modifications, and the like, it is possible to solve a problem not described above or achieve an effect not described above, or it is possible to solve only a part of the described problem or achieve only a part of the described effect.
As used herein, the term “comprise” and its variations are intended to mean open-ended terms, not excluding any other elements and/or components that are not recited herein. The same applies to the terms “include” , “have” , and their variations.
As used herein, a component suffixed with a term such as “member”, “portion”, “part”, “element”, “body”, and “structure” is intended to mean that there is a single such component or a plurality of such components.
As used herein, ordinal terms such as “first” and “second” are merely used for distinguishing purposes and there is no other intention (such as to connote a particular order) in using ordinal terms. For example, the mere use of “first element” does not connote the existence of “second element”; otherwise, the mere use of “second element” does not connote the existence of “first element”.
As used herein, approximating language such as “approximately”, “about”, and “substantially” may be applied to modify any quantitative representation that could permissibly vary without a significant change in the final result obtained. All of the quantitative representations recited in the present application shall be construed to be modified by approximating language such as “approximately”, “about”, and “substantially”.
As used herein, the phrase “at least one of A and B” is intended to be interpreted as “only A”, “only B”, or “both A and B”.
Obviously, numerous modifications and variations of the present disclosure are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the present disclosure may be practiced otherwise than as specifically described herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-123752 | Jul 2021 | JP | national |
