JP2020174467A - Motor drive system, motor drive method and program - Google Patents

Abstract

To provide a motor drive system, a motor drive method and a program, which decrease a possibility of allowing the operation amount of a servo motor to be unnecessarily long or short during a period since a stop command is input until the servo motor stops.SOLUTION: A motor drive system 1 comprises a servo control part 2 which controls operation of a servo motor 7. The servo control part 2 performs control which stops the servo motor 7 in such a manner that the operation amount of the servo motor 7 during a period since a stop command C1 for stopping the servo motor 7 is input until the servo motor 7 stops is in a braking range which is a predetermined range. The servo control part 2 has a braking control part 22. The braking control part 22 determines the braking range based on information on a position of a drive object 11 to be driven by the servo motor 7.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a motor drive system, a motor drive method and a program, and more particularly to a motor drive system, a motor drive method and a program for controlling the operation of a servomotor.

The motor control device described in Patent Document 1 realizes positioning control for a controlled object including a motor and a mechanical system to which the motor is connected by driving control of the motor. The motor control device includes a speed control unit that calculates and outputs a current command based on the speed command and the detection speed of the motor, and a current control unit that controls the drive current supplied to the motor based on the current command.

Japanese Unexamined Patent Publication No. 2015-008590

In such a motor control device, when a stop command is input from the outside in an emergency, for example, the motor is suddenly stopped by cutting off the supply of the drive current to the motor. However, for example, when a motor is used in a carrier, the sudden stop of the motor may cause the articles being conveyed by the carrier to fall off from the carrier. In addition, the sudden stop of the motor may impose a burden on the motor itself. As described above, a problem may occur due to the unnecessarily short operating amount of the motor from the input of the stop command to the stop of the motor.

The present disclosure provides a motor drive system, a motor drive method, and a program capable of reducing the possibility that the operating amount of the servomotor from the input of the stop command to the stop of the servomotor becomes unnecessarily long or short. The purpose is.

The motor drive system according to one aspect of the present disclosure includes a servo control unit that controls the operation of the servo motor. In the servo control unit, the amount of operation of the servomotor from the input of the stop command for stopping the servomotor to the stop of the servomotor is within the braking range which is a predetermined range. Controls to stop the servomotor. The servo control unit has a braking control unit. The braking control unit determines the braking range based on information about the position of the drive target driven by the servomotor.

The motor driving method according to one aspect of the present disclosure includes a stop step and a determination step. In the stop step, the operation amount of the servomotor from the input of the stop command for stopping the servomotor to the stop of the servomotor is within the braking range which is a predetermined range. Controls to stop the servo motor. The determination step determines the braking range based on information about the position of the drive target driven by the servomotor.

The program according to one aspect of the present disclosure causes one or more processors to execute the above motor driving method.

The present disclosure has an advantage that the possibility that the operating amount of the servomotor from the input of the stop command to the stop of the servomotor becomes unnecessarily long or short can be reduced.

FIG. 1 is a block diagram illustrating control of a servomotor when the motor drive system according to the embodiment is operating in response to stop control. FIG. 2 is a block diagram illustrating the control of the servomotor when the motor drive system of the above is operating corresponding to the basic control. FIG. 3A is an image diagram showing a state of movement of a conveyor equipped with the same motor drive system. FIG. 3B is an image diagram showing a stopped state of the same carrier. FIG. 4 is a flowchart when the motor drive system of the same operation operates in response to stop control. FIG. 5 is a graph showing an example of time changes in acceleration, speed, and coordinates of the motor drive system of the same. FIG. 6A is a graph showing an example of time changes in acceleration, speed, and coordinates of the motor drive system according to the first modification. FIG. 6B is a graph showing another example of time variation of acceleration, velocity and coordinates of the same motor drive system.

Hereinafter, the motor drive system according to the embodiment will be described with reference to the drawings. However, the following embodiments are only one of the various embodiments of the present disclosure. The following embodiments can be variously modified according to the design and the like as long as the object of the present disclosure can be achieved.

(1) Configuration As shown in FIG. 1, the motor drive system 1 of the present embodiment includes a servo control unit 2. The servo control unit 2 controls the operation of the servo motor 7. Further, the servo control unit 2 communicates with the host controller 8. The servo control unit 2 receives a command from the host controller 8 and controls the operation of the servomotor 7 in response to the command. Here, the servomotor 7 and the upper controller 8 are provided as an external configuration of the motor drive system 1, but at least one of the servomotor 7 and the upper controller 8 may be included in the motor drive system 1. ..

In the present embodiment, the host controller 8 is, for example, a server. At least a part of the host controller 8 and the servo control unit 2 is composed of a computer system having one or more processors and a memory. Further, it is not necessary that each block of the host controller 8 and the servo control unit 2 is composed of a computer system, and at least a part of them is composed of a computer system having one or more processors and memories. It may be configured. When the processor of the computer system executes the program recorded in the memory of the computer system, at least a part of the functions of the host controller 8 and the servo control unit 2 is realized. The program may be recorded in a memory, provided through a telecommunication line such as the Internet, or may be recorded and provided on a non-temporary recording medium such as a memory card.

The servomotor 7 drives the drive target 11. In the present embodiment, the servomotor 7 is a rotary motor having a stator, a rotor that rotates with respect to the stator, and an output shaft that rotates together with the rotor. The motor drive system 1 and the servomotor 7 of the present embodiment are provided in the conveyor 10 (moving body). The drive target 11 of this embodiment is the main body of the conveyor 10. The conveyor 10 includes a main body (drive target 11) including drive wheels, a servomotor 7, and a motor drive system 1. The servomotor 7 rotates the drive wheels via the output shaft to move the main body (drive target 11). As a result, the transport machine 10 can transport the article 12 (see FIG. 3A).

The motor drive system 1 further includes an encoder 41, a torque detection unit 42, an external scale 43, and an error detection unit 44.

The encoder 41 detects the rotation angle of the rotor of the servomotor 7. As the encoder 41, for example, a photoelectric encoder or a magnetic encoder can be adopted.

The torque detection unit 42 detects the operating torque of the servomotor 7. The torque detection unit 42 is, for example, a magnetostrictive strain sensor capable of detecting torsional strain. The magnetostrictive strain sensor detects a change in magnetic permeability according to the strain generated by applying torque to the output shaft of the servomotor 7 with a coil installed in the non-rotating part of the servomotor 7, and a voltage proportional to the strain. Output a signal.

The external scale 43 includes, for example, an optical sensor, an ultrasonic sensor, or an imaging device. The external scale 43 detects an object around the conveyor 10 (moving body) provided with the motor drive system 1. In the present embodiment, the external scale 43 detects whether or not an object exists in the path of the drive target 11, and if the object exists, obtains the distance between the object and the drive target 11.

The error detection unit 44 detects the occurrence of a specific event. When the error detection unit 44 detects the occurrence of a specific event, it outputs a stop command C1 (see FIG. 1) for urgently stopping the servomotor 7 to the servo control unit 2. The specific event is an event indicating an abnormality related to control by the motor drive system 1. Specific examples of a specific event include, for example, that the torque of the servomotor 7 is larger than the first threshold value, that the current supplied to the servomotor 7 is an overcurrent larger than the second threshold value, or that the drive target is driven. There is an obstacle in the course of 11.

As an example, the error detection unit 44 acquires the detection value of the operating torque of the servomotor 7 from the torque detection unit 42 in order to determine whether or not the torque of the servomotor 7 is larger than the first threshold value. .. Further, the error detection unit 44 includes a current sensor for determining whether or not the current supplied to the servomotor 7 is larger than the second threshold value, and detects the current supplied to the servomotor 7. The value is obtained from the current sensor. The current sensor includes, for example, a shunt resistor element or a Hall element current sensor. Further, the error detection unit 44 has acquired the detection result of the external scale 43 in order to determine whether or not there is an obstacle in the path of the drive target 11.

The servo control unit 2 controls the operation of the servomotor 7 by a fully closed loop method.

The servo control unit 2 has a braking control unit 22. The servo control unit 2 further includes a communication unit 21, a position control unit 23, a speed feedforward unit 24, a speed calculation unit 25, a speed control unit 26, a torque feedforward unit 27, and a torque control unit 28. , And a current control unit 29.

The braking control unit 22 controls the operation of the servomotor 7 when the servo control unit 2 makes an emergency stop of the servomotor 7. That is, the operation of the servo control unit 2 includes basic control (mode) for controlling the servomotor 7 based on a command from the host controller 8 and stop control (mode) for the servo control unit 2 to stop the servomotor 7 in an emergency. including. Details will be described later.

The communication unit 21 includes a communication interface for communicating with the host controller 8. As a communication method between the communication unit 21 and the host controller 8, an appropriate communication method of wireless communication or wired communication is adopted. In this embodiment, as an example, the communication unit 21 is set to a standard such as Wi-Fi (registered trademark), Bluetooth (registered trademark), ZigBee (registered trademark), or low power radio (specified low power radio) that does not require a license. Adopt compliant wireless communication that uses radio waves as a communication medium.

The communication unit 21 receives the input of the position command output from the host controller 8. The position command is a command for designating the rotation angle of the servomotor 7. The position command is input to the communication unit 21 as a position command value which is a value indicating the rotation angle of the servomotor 7.

Further, the host controller 8 outputs a stop command C1 (see FIG. 1). The communication unit 21 receives the input of the stop command C1 output from the host controller 8. The stop command C1 is a command for urgently stopping the servomotor 7. As will be described later, one of the problems of the present disclosure is to optimize the control for stopping the servomotor 7 in response to the stop command C1, and the drive target 11 to be stopped collides with the object 9 (see FIG. 3A). To reduce the possibility. The stop command C1 does not need to have information such as the stop position of the conveyor 10 or the servomotor 7, and may be input as a signal capable of determining at least whether or not the servomotor 7 needs to be stopped. The stop command C1 may be, for example, a binary signal indicating whether or not the servomotor 7 needs to be stopped.

Further, the host controller 8 can instruct the servomotor 7 to stop by the position command, separately from instructing the emergency stop of the servomotor 7 by the stop command C1. When the servomotor 7 is stopped in response to the position command, the position command includes, for example, information for designating the stop position of the conveyor 10. The servo control unit 2 controls the operation of the servomotor 7 so that the conveyor 10 stops at the stop position designated by the position command. The position command for stopping the servomotor 7 is, for example, when the transfer machine 10 is made to stand by, when the article 12 conveyed to the transfer machine 10 is unloaded, and when the article 12 is loaded on the transfer machine 10. At that time, it is output from the host controller 8.

Further, the host controller 8 outputs a parameter related to the control that the servo control unit 2 stops the servo motor 7 to the communication unit 21 in response to the stop command C1. Details will be described later.

(2) Basic Control Hereinafter, the operation flow of the motor drive system 1 when a position command (position command value) is input from the host controller 8 to the communication unit 21 will be described with reference to FIG.

The position control unit 23 calculates a value obtained by multiplying the difference (position deviation) between the position command value (rotation angle) acquired from the communication unit 21 and the rotation angle of the rotor detected by the encoder 41 by a predetermined position gain. It is generated as the first speed command value. The first speed command value is a command value that specifies the rotation speed of the servomotor 7.

The speed feed forward unit 24 differentiates the position command value acquired from the communication unit 21 to obtain a second speed command value, and multiplies the second speed command value by a predetermined speed feed forward gain to obtain a speed feed. Output as a forward command value.

The speed calculation unit 25 calculates the rotation speed of the rotor by time-differentiating the rotation angle of the rotor detected by the encoder 41.

The speed control unit 26 is a rotor calculated by the speed calculation unit 25 from the sum of the first speed command value output from the position control unit 23 and the speed feed forward command value output from the speed feed forward unit 24. A torque command value is generated based on the value obtained by subtracting the rotation speed of. The torque command value is a command value that specifies the operating torque of the servomotor 7.

The torque feedforward unit 27 generates a torque feedforward command value based on the position command value acquired from the communication unit 21.

The torque control unit 28 operates the servomotor 7 acquired from the torque detection unit 42 from the sum of the torque command value output from the speed control unit 26 and the torque feed forward command value output from the torque feed forward unit 27. A current command value is generated based on the value obtained by subtracting the detected torque value. The current command value is a command value that specifies the current supplied to the servomotor 7.

The current control unit 29 includes, for example, an inverter. The current control unit 29 supplies the servomotor 7 with a current corresponding to the current command value output from the torque control unit 28.

The servomotor 7 is driven by the current supplied from the current control unit 29 to operate the drive target 11.

As a result, the servo control unit 2 controls the torque of the servomotor 7 so that the position of the servomotor 7 becomes a position corresponding to the position command value output from the host controller 8. Since the torque of the servomotor 7 is limited by the current command value, the servo control unit 2 adjusts the magnitude of the current command value output from the torque control unit 28, for example, to position the position command value. It is possible to perform control according to. Alternatively, the servo control unit 2 can perform control according to the position command value by adjusting the magnitude of the position gain multiplied by the position deviation in the position control unit 23.

When operating in the basic control, the braking control unit 22 monitors whether or not the stop command C1 is input from the host controller 8. Further, when the error detection unit 44 detects the occurrence of a specific event based on, for example, the detection result of the external scale 43, the error detection unit 44 outputs a stop command C1 to the braking control unit 22 of the servo control unit 2. Then, when the braking control unit 22 detects that the stop command C1 has been input from at least one of the host controller 8 and the error detection unit 44, the servo control unit 2 shifts to the stop control operation.

(3) Stop Control Next, the operation flow of the motor drive system 1 when the stop command C1 is input to the servo control unit 2 will be described with reference to FIGS. 1, 3A, 3B, and 4.

When the host controller 8 determines that the carrier 10 needs to be stopped urgently, it outputs a stop command C1 to the communication unit 21 of the servo control unit 2. When the braking control unit 22 acquires the stop command C1 from the communication unit 21 (step ST1), the braking range is determined (step ST2), and the servomotor 7 stops after the stop command C1 is input to the servo control unit 2. The amount of operation of the servomotor 7 up to is determined (step ST3). Details of step ST2 will be described later. The braking control unit 22 generates and outputs a position command value according to the determined operating amount of the servomotor 7 (step ST4). The servo control unit 2 controls the servomotor 7 based on the position command value generated by the braking control unit 22. As a result, the servo control unit 2 controls the torque of the servo motor 7 so that the position of the servo motor 7 becomes a position corresponding to the position command value generated by the braking control unit 22 (step ST5), and finally. (See FIG. 3B). At this time, the flow in which the servo control unit 2 controls the servomotor 7 is such that the position command value from the host controller 8 in "(2) basic control" is replaced with the position command value generated by the braking control unit 22. Since it is the same as the content of "(2) Basic control", the description thereof will be omitted.

The host controller 8 continues to output the stop command C1 even after the stop command C1 is output. At this time, the braking control unit 22 has already shifted the servo control unit 2 to the stop control by the stop command C1 acquired first. Therefore, the braking control unit 22 does not receive the stop command C1 acquired after the second time until the servomotor 7 stops. The braking control unit 22 is not limited to a configuration in which the stop command C1 acquired after the second time is not received until the servomotor 7 is stopped, and also receives the stop command C1 acquired after the second time. Is also good. In this case, the braking control unit 22 generates a position command value according to the operating amount of the servomotor 7 each time the stop command C1 is acquired from the second time onward. Further, the host controller 8 may be configured to stop the output of the stop command C1 after outputting the stop command C1 a specified number of times. Alternatively, the host controller 8 may be configured to stop the output of the stop command C1 when it receives an ACK (a response signal indicating that the stop command C1 has been received) from the communication unit 21.

Further, when the error detection unit 44 detects the occurrence of a specific event, the error detection unit 44 outputs a stop command C1 to the braking control unit 22 of the servo control unit 2. Also in this case, the braking control unit 22 generates a position command value, and the servo control unit 2 stops the servomotor 7 based on the position command value generated by the braking control unit 22. After the stop command C1 is input to the braking control unit 22, the servo control unit 2 does not perform the basic control operation in response to the position command even if a new position command is input from the host controller 8. As described above, since the motor drive system 1 includes the error detection unit 44, the motor drive system 1 can stop the servomotor 7 by itself without depending on the stop command C1 from the host controller 8.

Even if a specific event is resolved after the error detection unit 44 generates the stop command C1, the servo control unit 2 continues the stop control. That is, the operation of the servomotor 7 is stopped even when the specific event is resolved. At this time, the stop command C1 generated by the error detection unit 44 is transmitted to the host controller 8 via the communication unit 21 and the like. When the host controller 8 acquires the stop command C1 from the servo control unit 2, the host controller 8 stops the output of the position command to the servo control unit 2. Then, for example, after the administrator who manages the conveyor 10 confirms the safety of the conveyor 10 and confirms that there is no abnormality, the administrator operates the host controller 8 or the like to send the servo control unit 2 to the servo control unit 2. Resume the output of the position command. As a result, the operation of the conveyor 10 is restarted. That is, the servo control unit 2 resumes the basic control operation based on the new position command output from the host controller 8.

As described above, the specific event is, for example, the presence of an obstacle in the path of the driving target 11. In this case, the obstacle may be moving or stationary. In any case, the error detection unit 44 outputs the stop command C1 when an obstacle is detected by the external scale 43. For example, when there are no obstacles in the path of the drive target 11, the error detection unit 44 ends the generation of the stop command C1.

By the way, the braking control unit 22 determines the amount of operation of the servomotor 7 with a certain width. That is, the braking control unit 22 determines the braking range, which is a predetermined range (step ST2), and finally, the servomotor from the input of the stop command C1 to the servo control unit 2 until the servomotor 7 stops. The amount of motion of 7 is determined to be a value within the braking range (step ST3). Then, in the servo control unit 2, the amount of operation of the servomotor 7 from the time when the stop command C1 is input to the servo control unit 2 until the servomotor 7 is stopped is within the braking range determined by the braking control unit 22. Control is performed to stop the servomotor 7 so as to be.

The braking control unit 22 acquires information regarding the position of the drive target 11 driven by the servomotor 7. The braking control unit 22 determines the braking range based on this information. Information regarding the position of the drive target 11 includes, for example, the coordinates of the object 9 (obstacles, etc.) existing in the path of the drive target 11, the coordinates of the drive target 11, the object 9 existing in the path of the drive target 11, and the drive target 11. Information such as whether or not there is an intrusion prohibited area in the path of the driving target 11 and the distance L1 between the two. In the present embodiment, the braking control unit 22 uses the distance L1 between the object 9 existing in the path of the driving target 11 and the driving target 11 as information regarding the position of the driving target 11. Further, in the example shown in FIGS. 3A and 3B, the object 9 is a wall. In FIG. 3A, the traveling direction of the drive target 11 (conveyor 10) is on the right side of the paper (see arrow 110 in FIG. 3A). The braking control unit 22 acquires the distance L1 detected by the external scale 43 from the external scale 43. The braking control unit 22 acquires the distance L1 in real time. That is, the braking control unit 22 acquires the distance L1 from the external scale 43 at predetermined time intervals.

As described above, the external scale 43 is used as a sensor for detecting information regarding the position of the drive target 11. The braking control unit 22 determines the braking range based on the output of the external scale 43. The external scale 43 of the present embodiment detects information about the position of the drive target 11 before and after the stop command C1 is input. However, the external scale 43 may detect the information about the position of the drive target 11 only before the stop command C1 is input, or detect the information about the position of the drive target 11 only after the stop command C1 is input. You may.

The braking control unit 22 determines the braking range within a range in which the driving target 11 does not enter the predetermined area R2. In the present embodiment, the predetermined area R2 is an area within a predetermined distance from the object 9 existing in the path of the driving target 11. In short, the motor drive system 1 controls the operation of the servomotor 7 so that the drive target 11 stops at a position separated from the object 9 by a predetermined distance or more.

In the present embodiment, for convenience of explanation, the braking control unit 22 will determine the stop area R1 of the drive target 11. The braking control unit 22 determines the braking range corresponding to the stop area R1. Then, the braking control unit 22 determines the amount of operation of the servomotor 7 until the servomotor 7 is stopped to a value within the braking range. That is, the braking control unit 22 sets a position command value for stopping the servomotor 7 while a specific position of the drive target 11 (for example, the tip 111 in the traveling direction of the drive target 11) is in the stop area R1. The servo control unit 2 generates and controls the operation of the servo motor 7 according to the position command value. However, the braking control unit 22 may determine the braking range without determining the stop area R1. In the following description, the coordinates of the drive target 11 refer to the coordinates of the tip 111.

The braking control unit 22 determines the stop area R1 from the drive target 11 when the stop command C1 is input, based on the distance L1 between the object 9 and the drive target 11 acquired from the external scale 43. The area is determined to be in front of the area R2 of. In the present embodiment, the boundary of the stop area R1 on the object 9 side (right side of the paper in FIG. 3A) and the boundary of the predetermined area R2 on the opposite side of the stop area R2 from the object 9 side (left side of the paper in FIG. 3A) overlap. ing.

The braking control unit 22 determines the pattern of the time change of the acceleration of the servomotor 7 after the stop command C1 is input. That is, since the pattern is not determined by the information contained in the stop command C1 but is determined by the braking control unit 22, the host controller 8 sends a signal instructing the pattern to the braking control unit 22. You don't have to give it. The pattern is, for example, a pattern in which the acceleration of the servomotor 7 is kept constant as shown in FIG. 5, or a pattern in which the acceleration of the servomotor 7 is continuously changed as shown in FIG. 6B. The braking control unit 22 generates a position command value according to the determined pattern. Here, the acceleration in the direction of increasing the speed of the servomotor 7 is defined as a positive acceleration, and the acceleration in the direction of decreasing the speed of the servomotor 7 is defined as a negative acceleration. In the present embodiment, the acceleration of the servomotor 7 after the stop command C1 is input is always 0 or less, but the acceleration of the servomotor 7 may temporarily exceed 0.

FIG. 5 illustrates an example of the relationship between the speed and acceleration of the servomotor 7, the coordinates of the drive target 11 on the coordinate axes along the traveling direction of the drive target 11, and time. The time point T1 is the time when the stop command C1 is input, and the time point T2 is the time when the servomotor 7 is stopped. The coordinates u1 are the coordinates of the drive target 11 at the time point T1, and the coordinates u2 are the coordinates of the drive target 11 at the time point T2. The coordinates u3 are the coordinates of the object 9. The coordinates r1 are the coordinates of the boundary of the stop area R1 far from the object 9, and the coordinates r2 are the coordinates of the boundary of the stop area R1 near the object 9. The moving distance L2 is the moving distance of the drive target 11 from the input of the stop command C1 to the stop of the servomotor 7. Here, at a time point before the time point T1, the servomotor 7 is moving at a constant speed, and the acceleration of the servomotor 7 is set to 0.

The braking control unit 22 shown in FIG. 1 has a pattern of time change of acceleration (deceleration) of the servomotor 7 after the stop command C1 is input within a range in which the operating amount of the servomotor 7 does not exceed the upper limit of the braking range. To determine. Here, the upper limit of the braking range is a value corresponding to the case where the moving amount of the drive target 11 (the operating amount of the servomotor 7) is the largest in the braking range. That is, the braking control unit 22 determines the above pattern so that the carrier 10 does not approach the object 9 beyond the coordinates r2 of the boundary on the side of the stop area R1 that is closer to the object 9. As a result, the possibility that the drive target 11 collides with the object 9 can be reduced.

In the present embodiment, the braking control unit 22 determines the above pattern so that the acceleration of the servomotor 7 is kept constant from the time when the stop command C1 is input until the servomotor 7 is stopped. That is, the servomotor 7 is decelerated at a constant deceleration. Here, the braking control unit 22 calculates the magnitude of the deceleration of the servomotor 7 so that the servomotor 7 stops until the drive target 11 exceeds the coordinates r2 and approaches the object 9.

Further, the braking control unit 22 determines the above pattern within a range in which the absolute value (deceleration) of the acceleration of the servomotor 7 does not fall below a predetermined value (lower limit value). Therefore, the servomotor 7 is always decelerated at a deceleration of the predetermined value or more regardless of the distance L1 between the drive target 11 and the object 9 at the time T1 when the stop command C1 is input.

As described above, the braking control unit 22 determines the braking range (stop area R1) to be a range in which the drive target 11 does not enter the predetermined area R2. Here, the predetermined area R2 may be an area determined regardless of the presence or absence of the object 9. For example, the predetermined area R2 may be a preset prohibited area. Information regarding the position of the no-entry area may be stored in advance in the memory of the motor drive system 1, for example.

Further, when the object 9 and the entry prohibition area do not exist in the path of the drive target 11, the braking control unit 22 determines in advance the pattern of the time change of the acceleration of the servomotor 7 after the stop command C1 is input. Make the pattern. The predetermined pattern is, for example, a pattern in which the absolute value (deceleration) of acceleration is kept at the predetermined value (lower limit value), and is stored in advance in the memory of the motor drive system 1.

Further, the braking control unit 22 receives input of parameters for determining the braking range. The parameters include, for example, a parameter for determining the size of the stop area R1 and a parameter for determining the size of a predetermined area R2 (that is, the distance between the object 9 and the stop area R1). Includes at least one. The parameters are input to the braking control unit 22 from the host controller 8 via the communication unit 21, for example. The parameters may be input to the motor drive system 1 from a device other than the host controller 8, for example, a server, a personal computer, a mobile terminal, a tablet terminal, or a dedicated terminal. Further, the motor drive system 1 may include, for example, an input interface for inputting parameters by an operator's operation.

According to the present embodiment described above, the braking range (stop area R1) is determined according to the information regarding the position of the drive target 11. Therefore, it is possible to reduce the possibility that the operating amount of the servomotor 7 from the input of the stop command C1 to the stop of the servomotor 7 becomes unnecessarily long or short.

Here, as a comparative example with the present embodiment, when the stop command C1 is input to the servo control unit 2, the deceleration (negative acceleration) determined in advance is constant regardless of the position of the drive target 11. An example is assumed in which the servomotor 7 is stopped. For example, it is assumed that the distance L1 from the drive target 11 to the object 9 in the path of the drive target 11 when the stop command C1 is input is 10 m. In this case, in the above comparative example, the servomotor 7 is decelerated at a predetermined constant deceleration (negative acceleration), and the drive target 11 is stopped, for example, at a position where the distance L1 is 5 m. .. On the other hand, in the present embodiment, the braking control unit 22 determines that, for example, when the stop command C1 is input, the distance L1 from the drive target 11 to the object 9 in the path of the drive target 11 is sufficiently long. Therefore, the servomotor 7 can be decelerated with a deceleration smaller than that of the above comparative example, and the drive target 11 can be stopped at a position where the distance L1 is 2 m. In the present embodiment, the load on the servomotor 7 can be reduced by reducing the deceleration. Further, when the transfer machine 10 is decelerated, it may be possible to suppress the occurrence of the position of the object to be conveyed (article 12) conveyed by the transfer machine 10 moving or dropping from the transfer machine 10.

Further, for example, it is assumed that the distance L1 from the drive target 11 to the object 9 in the path of the drive target 11 when the stop command C1 is input is 4 m. In this case, in the above comparative example, the servomotor 7 is decelerated by a predetermined constant deceleration (negative acceleration), but since it takes 5 m for the drive target 11 to stop, the drive target 11 is an object. It will collide with 9. On the other hand, in the present embodiment, the braking control unit 22 decelerates the servomotor 7 at a deceleration larger than that of the above comparative example so that the drive target 11 can avoid colliding with the object 9, for example. The drive target 11 can be stopped at a position where the distance L1 is 1 m.

As described above, according to the present embodiment, it is possible to optimize the control for stopping the servomotor 7.

(Modification example 1)
Hereinafter, the first modification of the embodiment will be described with reference to FIGS. 6A and 6B. The same components as those in the embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the first modification, the braking control unit 22 has a function of determining a pattern of time change of the acceleration of the servomotor 7 after the stop command C1 is input so that the acceleration of the servomotor 7 changes continuously. Have. More specifically, the braking control unit 22 determines the above pattern as follows. As shown in FIG. 6A, it is assumed that the servomotor 7 is continuously driven at a constant acceleration after the stop command C1 is input, and the servomotor 7 is stopped at the upper limit of the braking range. Under this assumption, the braking control unit 22 continuously changes the acceleration of the servomotor 7 as shown in FIG. 6B when the absolute value of the constant acceleration (negative value) is lower than the threshold value Th1. , Determine the above pattern. On the other hand, the braking control unit 22 keeps the acceleration of the servomotor 7 at the constant acceleration as shown in FIG. 6A when the absolute value of the constant acceleration exceeds the threshold Th1 and matches the threshold Th1. As described above, the above pattern is determined. That is, in this case, the servomotor 7 is decelerated at the constant acceleration.

FIG. 6A shows the time change of the acceleration and speed of the servomotor 7 when the servomotor 7 is continuously driven at a constant acceleration from the time point T1 when the stop command C1 is input. It is assumed that the servomotor 7 stops at the time point T2, and at this time, the amount of movement of the servomotor 7 after the stop command C1 is input has reached the upper limit of the braking range. That is, the coordinates of the drive target 11 when the servomotor 7 is stopped coincide with the coordinates r2 (see FIG. 5) of the boundary of the stop area R1 on the side closer to the object 9.

When the stop command C1 is input, the braking control unit 22 calculates whether or not the absolute value of the constant acceleration is below the threshold Th1. The threshold value Th1 may be stored in advance in the memory of the motor drive system 1, for example. When the absolute value of the constant acceleration exceeds the threshold Th1 or matches the threshold Th1, the braking control unit 22 determines the pattern so as to keep the acceleration of the servomotor 7 at the constant acceleration. Generate a position command value according to the pattern. Therefore, the servo control unit 2 controls the servomotor 7 so as to stop the servomotor 7 at a speed and acceleration as shown in FIG. 6A.

On the other hand, when the absolute value of the constant acceleration is lower than the threshold value Th1, the braking control unit 22 determines the pattern of the time change of the acceleration of the servomotor 7 as shown in FIG. 6B. In FIG. 6B, the acceleration of the servomotor 7 is continuously changing. More specifically, the absolute value of the acceleration of the servomotor 7 gradually increases from the time point T1 and then gradually decreases to 0 at the time point T2. As a result, from the time point T1 to the time point T2, the acceleration of the servomotor 7 increases or decreases so as to draw an arc in FIG. 6B. Due to such a time change of acceleration, the time change of the speed of the servomotor 7 becomes S-shaped in FIG. 6B.

By continuously changing the acceleration of the servomotor 7 in this way, the load on the servomotor 7 may be reduced. Further, by continuously changing the acceleration, it may be possible to reduce the possibility that the article 12 transported by the transport machine 10 will fall off from the transport machine 10.

In FIG. 6B, the braking control unit 22 generates a position command value such that the movement amount of the servomotor 7 from the time T1 when the stop command C1 is input to the time T2 when the servomotor 7 stops is within the braking range. .. As a result, it is possible to realize control that continuously changes the acceleration of the servomotor 7 while suppressing the drive target 11 from colliding with the object 9. Actually, the braking control unit 22 generates a position command value such that the movement amount of the servomotor 7 from the time point T1 to the time point T2 is the upper limit of the braking range. That is, the coordinates of the drive target 11 when the servomotor 7 is stopped coincide with the coordinates r2 (see FIG. 5) of the boundary of the stop area R1 on the side closer to the object 9.

Note that the time point T2 at which the servomotor 7 stops in FIG. 6A and the time point T2 at which the servomotor 7 stops in FIG. 6B may or may not coincide with each other.

Further, the braking control unit 22 may determine the above pattern so that the acceleration of the servomotor 7 changes continuously as shown in FIG. 6B without making a determination using the threshold value Th1. Alternatively, the pattern of the time change of the acceleration of the servomotor 7 may be switched between the pattern as shown in FIG. 6B and the pattern as shown in FIG. 6A by the user's operation.

(Other variants)
Hereinafter, other modifications of the embodiment are listed. The following modifications may be realized in appropriate combinations.

The same function as the motor drive system 1 may be embodied by a motor drive method, a (computer) program, a non-temporary recording medium on which the program is recorded, or the like.

The motor driving method according to one aspect includes a stop step and a determination step. In the stop step, the amount of operation of the servomotor 7 from the input of the stop command C1 for stopping the servomotor 7 to the stop of the servomotor 7 is within the braking range which is a predetermined range. Control is performed to stop the servomotor 7. The determination step determines the braking range based on information about the position of the drive target 11 driven by the servomotor 7.

The program according to one aspect is a program for causing one or more processors to execute the above-mentioned motor driving method.

The motor drive system 1 in the present disclosure includes a computer system. The main configuration of a computer system is a processor and memory as hardware. When the processor executes the program recorded in the memory of the computer system, the function as the motor drive system 1 in the present disclosure is realized. The program may be pre-recorded in the memory of the computer system, may be provided through a telecommunications line, and may be recorded on a non-temporary recording medium such as a memory card, optical disk, hard disk drive, etc. readable by the computer system. May be provided. A processor in a computer system is composed of one or more electronic circuits including a semiconductor integrated circuit (IC) or a large scale integrated circuit (LSI). The integrated circuit such as IC or LSI referred to here has a different name depending on the degree of integration, and includes an integrated circuit called a system LSI, VLSI (Very Large Scale Integration), or ULSI (Ultra Large Scale Integration). Further, an FPGA (Field-Programmable Gate Array) programmed after the LSI is manufactured, or a logical device capable of reconfiguring the junction relationship inside the LSI or reconfiguring the circuit partition inside the LSI should also be adopted as a processor. Can be done. A plurality of electronic circuits may be integrated on one chip, or may be distributed on a plurality of chips. The plurality of chips may be integrated in one device, or may be distributed in a plurality of devices. The computer system referred to here includes a microcontroller having one or more processors and one or more memories. Therefore, the microcontroller is also composed of one or more electronic circuits including a semiconductor integrated circuit or a large-scale integrated circuit.

Further, it is not an essential configuration for the motor drive system 1 that a plurality of functions in the motor drive system 1 are integrated in one housing, and the components of the motor drive system 1 are dispersed in a plurality of housings. It may be provided. Further, at least a part of the functions of the motor drive system 1 may be realized by a cloud (cloud computing) or the like.

On the contrary, in the embodiment, at least a part of the functions of the motor drive system 1 distributed in a plurality of devices may be integrated in one housing.

The servo motor 7 is not limited to the rotary motor, and may be a linear motor.

The drive target 11 is not limited to the carrier. The drive target 11 may be, for example, a vehicle such as an automobile, a ship, an aircraft, a forklift, or a moving body such as a mobile robot. Alternatively, the drive target 11 is, in addition to the moving body, at least one of the drive targets 11, such as an electric winder for winding a thread or paper, an electric drill, an electric driver, a lathe, or an electric pump. The unit may be a device that rotates or reciprocates. The braking control unit 22 determines the braking range based on the information regarding the position of the drive target 11. Here, when the drive target 11 is an electric winder, the position of the drive target 11 is, for example, , Corresponds to the rotation position of the drive target 11. The information about the rotation position may include not only the rotation angle of 0 to 360 degrees but also the total number of rotations from a certain point in time.

Further, the braking control unit 22 changes the acceleration of the servomotor 7 over time so that the absolute value of the acceleration of the servomotor 7 does not exceed a predetermined value within the range in which the movement amount of the servomotor 7 does not exceed the braking range. The pattern may be determined.

(Summary)
From the embodiments described above, the following aspects are disclosed.

The motor drive system 1 according to the first aspect includes a servo control unit 2 that controls the operation of the servo motor 7. In the servo control unit 2, the amount of operation of the servomotor 7 from the time when the stop command C1 for stopping the servomotor 7 is input until the servomotor 7 is stopped is within the braking range which is a predetermined range. Control is performed to stop the servomotor 7 as described above. The servo control unit 2 has a braking control unit 22. The braking control unit 22 determines the braking range based on the information regarding the position of the drive target 11 driven by the servomotor 7.

According to the above configuration, the braking range is determined according to the information regarding the position of the drive target 11, so that the amount of operation of the servomotor 7 from the input of the stop command C1 to the stop of the servomotor 7 is determined. The possibility of unnecessarily long or short can be reduced.

Further, in the motor drive system 1 according to the second aspect, in the first aspect, the braking control unit 22 receives an input of a parameter for determining a braking range.

According to the above configuration, the braking range can be adjusted by inputting a parameter to the braking control unit 22.

Further, in the motor drive system 1 according to the third aspect, in the first or second aspect, the braking control unit 22 determines the braking range based on the output of the sensor (external scale 43). The sensor detects information about the position of the drive target 11 after the stop command C1 is input.

According to the above configuration, by using the sensor (external scale 43), more detailed information regarding the position of the drive target 11 can be obtained.

Further, in the motor drive system 1 according to the fourth aspect, in any one of the first to third aspects, the servomotor 7 moves the drive target 11. The braking control unit 22 determines the braking range within a range in which the driving target 11 does not enter the predetermined area R2.

According to the above configuration, the possibility that the drive target 11 invades the predetermined area R2 can be reduced.

Further, in the motor drive system 1 according to the fifth aspect, in any one of the first to fourth aspects, the braking control unit 22 changes the acceleration of the servomotor 7 over time after the stop command C1 is input. Determine the pattern of.

According to the above configuration, since it is not necessary to give the braking control unit 22 a signal indicating the pattern of the acceleration of the servomotor 7 over time, the processing required for the control of the braking control unit 22 can be reduced.

Further, in the motor drive system 1 according to the sixth aspect, in the fifth aspect, the braking control unit 22 has input the stop command C1 within a range in which the operating amount of the servomotor 7 does not exceed the upper limit of the braking range. The pattern of the time change of the acceleration of the servomotor 7 after that is determined.

According to the above configuration, the possibility that the servomotor 7 operates beyond the upper limit of the braking range can be reduced.

Further, in the motor drive system 1 according to the seventh aspect, in the fifth or sixth aspect, the braking control unit 22 issues a stop command C1 within a range in which the absolute value of the acceleration of the servomotor 7 does not fall below a predetermined acceleration. The pattern of the time change of the acceleration of the servomotor 7 after being input is determined.

According to the above configuration, the servomotor 7 can be stopped earlier than in the case where the absolute value of the acceleration of the servomotor 7 is lower than the predetermined acceleration.

Further, in the motor drive system 1 according to the eighth aspect, in any one of the fifth to seventh aspects, the braking control unit 22 causes the stop command C1 so that the acceleration of the servomotor 7 changes continuously. Has a function of determining the pattern of the time change of the acceleration of the servomotor 7 after the input of.

According to the above configuration, the load on the servomotor 7 can be reduced as compared with the case where the acceleration of the servomotor 7 changes discontinuously.

Further, in the motor drive system 1 according to the ninth aspect, in any one of the first to eighth aspects, the servo control unit 2 has a communication unit 21. The communication unit 21 communicates with the host controller 8. The host controller 8 outputs a command including the stop command C1 to the servo control unit 2.

According to the above configuration, the servo control unit 2 can be controlled by the host controller 8.

Further, the motor drive system 1 according to the tenth aspect further includes an error detection unit 44 in any one of the first to ninth aspects. When the error detection unit 44 detects the occurrence of a specific event, the error detection unit 44 outputs a stop command C1 to the servo control unit 2.

According to the above configuration, the servomotor 7 can be stopped when a specific event occurs. Further, since it is possible to determine to stop the servomotor 7 in the motor drive system 1 without waiting for the input of the stop command C1 from the host controller 8, the stop operation can be performed quickly.

Further, the motor drive system 1 according to the eleventh aspect further includes a servomotor 7 in any one of the first to tenth aspects.

According to the above configuration, it is possible to provide the motor drive system 1 integrally including the servomotor 7.

Configurations other than the first aspect are not essential configurations for the motor drive system 1, and can be omitted as appropriate.

Further, the motor driving method according to the twelfth aspect includes a stop step and a determination step. In the stop step, the amount of operation of the servomotor 7 from the input of the stop command C1 for stopping the servomotor 7 to the stop of the servomotor 7 is within the braking range which is a predetermined range. Control is performed to stop the servomotor 7. The determination step determines the braking range based on information about the position of the drive target 11 driven by the servomotor 7.

According to the above configuration, the braking range is determined according to the information regarding the position of the drive target 11, so that the amount of operation of the servomotor 7 from the input of the stop command C1 to the stop of the servomotor 7 is determined. The possibility of being unnecessarily long or short can be reduced.

Further, the program according to the thirteenth aspect causes one or more processors to execute the motor driving method according to the twelfth aspect.

According to the above configuration, the braking range is determined according to the information regarding the position of the drive target 11, so that the amount of operation of the servomotor 7 from the input of the stop command C1 to the stop of the servomotor 7 is determined. The possibility of being unnecessarily long or short can be reduced.

Not limited to the above aspects, various configurations (including modifications) of the motor drive system 1 according to the embodiment can be embodied by a motor drive method and a program.

1 Motor drive system 11 Drive target 2 Servo control unit 21 Communication unit 22 Braking control unit 43 External scale (sensor)
44 Error detection unit 7 Servo motor 8 Upper controller C1 Stop command R2 Predetermined area Th1 Threshold

Claims (13)

Equipped with a servo control unit that controls the operation of the servo motor
In the servo control unit, the amount of operation of the servomotor from the input of the stop command for stopping the servomotor to the stop of the servomotor is within the braking range which is a predetermined range. Control to stop the servo motor
The servo control unit has a braking control unit that determines the braking range based on information about the position of a drive target driven by the servo motor.
Motor drive system. The braking control unit accepts input of parameters for determining the braking range.
The motor drive system according to claim 1. The braking control unit determines the braking range based on the output of the sensor that detects information about the position of the driving target after the stop command is input.
The motor drive system according to claim 1 or 2. The servomotor moves the drive target,
The braking control unit determines the braking range within a range in which the driving target does not enter a predetermined area.
The motor drive system according to any one of claims 1 to 3. The braking control unit determines the pattern of time change of the acceleration of the servomotor after the stop command is input.
The motor drive system according to any one of claims 1 to 4. The braking control unit determines a pattern of time change of acceleration of the servomotor after the stop command is input within a range in which the operating amount of the servomotor does not exceed the upper limit of the braking range.
The motor drive system according to claim 5. The braking control unit determines a pattern of time change of the acceleration of the servomotor after the stop command is input within a range in which the absolute value of the acceleration of the servomotor does not fall below a predetermined acceleration.
The motor drive system according to claim 5 or 6. The braking control unit has a function of determining a pattern of time change of the acceleration of the servomotor after the stop command is input so that the acceleration of the servomotor changes continuously.
The motor drive system according to any one of claims 5 to 7. The servo control unit has a communication unit for communicating with a host controller that outputs a command including the stop command to the servo control unit.
The motor drive system according to any one of claims 1 to 8. An error detection unit that outputs the stop command to the servo control unit when the occurrence of a specific event is detected is further provided.
The motor drive system according to any one of claims 1 to 9. The servo motor is further provided.
The motor drive system according to any one of claims 1 to 10. The servomotor is stopped so that the amount of operation of the servomotor between the time when the stop command for stopping the servomotor is input and the time when the servomotor is stopped is within the braking range which is a predetermined range. The stop step to control and
It comprises a determination step of determining the braking range based on information about the position of a drive target driven by the servomotor.
Motor drive method. A method for causing one or more processors to execute the motor driving method according to claim 12.
program.

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