Motor control device and motor control method

Abstract

A motor control device (2) according to the present disclosure is capable of executing pressure control, which is control of a motor (3) based on a pressure command, and first control, which is control of the motor (3) based on a first command other than the pressure command. The motor control device includes: a control information storage unit (21) that stores control information including first control information used to generate the first command, second control information used to generate the pressure command, and order information indicating an execution order of the first control and the pressure control as second control; and a motor control unit (30) that controls the motor (3) on the basis of the control information.

Description

Motor control device and motor control method

[0001] The present disclosure relates to a motor control device and a motor control method for controlling a motor.

[0002] There is known a technology for performing machining while applying pressure to an object to be pressed (hereinafter also referred to as a workpiece) using a motor. Patent Document 1 discloses a system including a motor, a motor control device, and a host control device. The motor control device described in Patent Document 1 performs position control and pressure control by controlling the motor using pressure commands and position commands generated by the host control device.

[0003] JP 2016-226200 A

[0004] However, in the motor control system described in Patent Document 1, when switching between position control and pressure control of the motor, the host control device switches between inputting a pressure command to the motor control device and inputting a position command to the motor control device using software. Therefore, in the motor control system described in Patent Document 1, the operation of the motor control device depends on the calculation cycle and communication cycle of the host control device. As a result, the motor control system described in Patent Document 1 has a problem in that the timing of switching between position control and pressure control is delayed from the timing at which the switching should actually occur, which could result in a shock caused by the pressure mechanism colliding with the workpiece.

[0005] The present disclosure has been made in view of the above, and aims to provide a motor control device that can reduce shock when switching motor control.

[0006] In order to solve the above-mentioned problems and achieve the objectives, the motor control device disclosed herein is a motor control device that is capable of executing pressure control, which is control of a motor based on a pressure command, and first control, which is control of a motor based on a first command, which is a command other than a pressure command, and is equipped with a control information memory unit that stores control information including first control information used to generate the first command, second control information used to generate the pressure command, and sequence information that indicates the sequence of execution of the first control and the second control, which is pressure control, and a motor control unit that controls the motor based on the control information.

[0007] The motor control device according to the present disclosure has the effect of reducing shock when switching motor control.

[0008] FIG. 1 is a diagram showing an example of the configuration of a motor control system according to an embodiment; FIG. 2 is a diagram showing an example of pressurization using a motor according to an embodiment; FIG. 3 is a flowchart showing an example of a motor control processing procedure in a motor control device according to an embodiment; FIG. 4 is a diagram showing an example of control information according to an embodiment; FIG. 5 is a diagram showing an example of a series of operations according to an embodiment; FIG. 6 is a diagram showing another example of control information according to an embodiment in which a sequence from a feed operation to a depressurization operation is repeated twice;

[0009] A motor control device and a motor control method according to an embodiment will be described in detail below with reference to the accompanying drawings.

[0010] 1 is a diagram showing an example of the configuration of a motor control system 100 according to an embodiment. The motor control system 100 of the embodiment includes an external device 1, a motor control device 2, and a motor 3. The motor control system 100 is used in, for example, a bonding device, a press molding device, an injection molding device, a press processing machine that performs bending, drawing, punching, etc. However, the motor control system 100 may be used in any processing system that performs processing including a pressurizing operation using the motor 3, and its uses are not limited to these.

[0011] The external device 1 is a higher-level control device than the motor control device 2, i.e., a higher-level control device. For example, based on input from a user, the external device 1 generates a start signal that instructs the motor control device 2 to start controlling the motor 3, and outputs the generated start signal to the motor control device 2. The external device 1 may also store control information including control parameters used to control the motor 3. The control parameters may be stored in the external device 1 in advance, may be set by the user, or may be determined based on machining conditions input by the user. Alternatively, initial values ​​of the control parameters may be stored in the external device 1 in advance, and the external device 1 may be able to change at least some of the control parameters by receiving input from the user to change the control parameters. Details of the control parameters and the control information will be described later.

[0012] An encoder 4 is attached to the motor 3, which detects the rotational position and rotational speed of the motor 3. The encoder 4 outputs the detection result as an encoder feedback signal to the motor control device 2. The motor 3 also drives a pressure head 5, which is capable of applying pressure to a workpiece, which is an object to be pressed. The pressure head 5 is provided with a pressure sensor 6 that detects pressure. The pressure sensor 6 detects pressure and outputs the detection result as a pressure feedback signal to the motor control device 2. The pressure sensor 6 is composed of, for example, a load cell and a load cell amplifier, but is not limited to this.

[0013] The motor control device 2 is capable of executing pressure control, which is control of the motor 3 based on a pressure command, and first control, which is control of the motor 3 based on a first command, which is a command other than a pressure command. The first control includes at least one of position control, speed control, and torque control. Hereinafter, pressure control based on a pressure command will also be referred to as second control. The motor control device 2 causes a series of operations of the motor 3 through a series of controls that includes switching from the first control to the second control. In this embodiment, the series of controls performed by the motor control device 2 is composed of two or more unit controls. That is, the motor control device 2 controls a series of operations of the motor 3 through a series of controls that includes multiple unit controls. Each unit control is, for example, a first control or a second control.

[0014] 1 shows an example in which the first control is position control, and the motor control device 2 has a control system for position control and a control system for pressure control, and performs a series of controls including switching from position control to pressure control. Note that, although an example in which the motor control device 2 has a control system for position control and a control system for pressure control will be described below, this is not limiting, and the configuration and operation of this embodiment can also be applied to cases in which the motor control device 2 has a control system for speed control or torque control instead of the control system for position control.

[0015] 1 , motor control device 2 includes control information acquisition unit 20, control information storage unit 21, and motor control unit 30. Motor control unit 30 includes command determination unit 22, position command generation unit 23, pressure command generation unit 24, position control unit 25, pressure control unit 26, control switching unit 27, speed control unit 28, and current control unit 29.

[0016] The control information acquisition unit 20 acquires the control information and stores the acquired control information in the control information storage unit 21. If the control information is stored in the external device 1, the control information acquisition unit 20 acquires the control information by receiving the control information from the external device 1, for example, before starting control of the motor 3. Alternatively, the control information acquisition unit 20 may acquire the control information by accepting input from a user. Note that the control information acquisition unit 20 itself may be an input means such as a touch panel or a keyboard that accepts input from a user, or an input means (not shown) may be provided separately, and the control information acquired by the input means may be acquired by the control information acquisition unit 20.

[0017] The control information storage unit 21 stores control information. In this embodiment, the control information includes position control parameters that are control parameters related to position control, pressure control parameters that are control parameters related to pressure control, and sequence information that indicates the sequence of execution of unit controls. As described above, a unit control constitutes a series of controls. During one unit control, control is performed using the same control information corresponding to that unit control, i.e., control information including a set of control parameters corresponding to that unit control.

[0018] When a control system for speed control or torque control is used instead of a control system for position control, the control information includes control parameters for speed control or torque control, pressure control parameters, and sequence information. The control information may be stored in advance in the control information storage unit 21. In this case, the control information acquisition unit 20 may not be provided.

[0019] The motor control unit 30 controls the motor 3 using control information stored in the control information storage unit 21. The command determination unit 22 determines whether to generate a first command or a pressure command. Specifically, the command determination unit 22 reads the control information stored in the control information storage unit 21 for each unit control, determines whether the unit control to be executed based on the read control information is a position control, which is a pressure control, and switches the output destination of the control information between the position command generation unit 23 and the pressure command generation unit 24 depending on the determination result. For example, if the unit control to be executed is a pressure control, the command determination unit 22 outputs the read control information to the pressure command generation unit 24, and if the unit control to be executed is a position control, the command determination unit 22 outputs the read control information to the position command generation unit 23. Furthermore, the command determination unit 22 generates a switching control signal for controlling switching of the control switching unit 27 based on the determination result and outputs the generated switching control signal to the control switching unit 27. The switching control signal will be described later.

[0020] Position command generator 23 is an example of a first command generator that generates a first command based on control information when command determiner 22 determines to issue a first command. In particular, upon receiving position control information from command determiner 22, position command generator 23 generates a position command based on the received position control information and outputs the generated position command to position controller 25. Note that if the position control information includes a position control gain (information indicating the position control gain), position command generator 23 outputs the position control gain as gain specification information to position controller 25 together with the position command.

[0021] The position control unit 25 is a first control unit that generates a first speed command by feedback control based on the difference between the first command and first feedback information used for the first control. Specifically, the position control unit 25 generates a first speed command using the position command and an encoder feedback signal, which is the first feedback information, and outputs the generated first speed command to the control switching unit 27. For example, the position control unit 25 generates a speed command corresponding to the difference between a command value indicated by the position command and a position indicated by the encoder feedback signal through feedback control such as proportional control, integral control, proportional-integral control, or PID (Proportional Integral Differential) control. The position control unit 25 can set a position control gain, which is a control gain that indicates tracking ability in feedback control, to a specified value from among multiple values. When gain designation information is received from the position command generation unit 23, the position control unit 25 sets the position control gain to a value corresponding to the received gain designation information and then generates the first speed command.

[0022] The pressure command generation unit 24 is a second command generation unit that generates a second command, which is a pressure command, based on the control information when the command determination unit 22 determines to determine a pressure command. In detail, when the pressure command generation unit 24 receives pressure control information from the command determination unit 22, it generates a pressure command based on the received pressure control information and outputs the generated pressure command to the pressure control unit 26. Note that when the pressure control information includes a pressure control gain (information indicating the pressure control gain), the pressure command generation unit 24 outputs the pressure control gain to the pressure control unit 26 as gain designation information together with the pressure command.

[0023] The pressure control unit 26 is a second control unit that generates a second speed command by feedback control based on the difference between the second command and feedback information of the pressure generated by driving the motor 3. Specifically, the pressure control unit 26 generates a second speed command using the pressure command and a pressure feedback signal, which is pressure feedback information, and outputs the generated second speed command to the control switching unit 27. For example, the pressure control unit 26 generates, as the second speed command, a speed command corresponding to the deviation between a command value indicated by the pressure command and the pressure indicated by the pressure feedback signal, by feedback control such as proportional control, integral control, proportional-integral control, or PID control. The pressure control unit 26 can set a pressure control gain, which is a control gain that indicates the tracking ability in feedback control, to a specified value from among multiple values. When gain designation information is received from the pressure command generation unit 24, the pressure control unit 26 sets the pressure control gain to a value corresponding to the received gain designation information and then generates the second speed command.

[0024] The control switching unit 27 inputs a first speed command or a second speed command to the speed control unit 28 based on the determination result of the command determination unit 22. More specifically, the control switching unit 27 switches the speed command input to the speed control unit 28 between the first speed command output from the position control unit 25 and the second speed command output from the pressure control unit 26 based on the switching control signal received from the command determination unit 22. The switching control signal indicates an instruction to input the first speed command to the speed control unit 28 when the determination result of the command determination unit 22 is position control, and indicates an instruction to input the second speed command to the speed control unit 28 when the determination result of the command determination unit 22 is pressure control. As a result, the control switching unit 27 outputs the first speed command to the speed control unit 28 when the determination result of the command determination unit 22 is position control, and outputs the second speed command to the speed control unit 28 when the determination result of the command determination unit 22 is pressure control. In addition, instead of the command determination unit 22 controlling the switching of the control switching unit 27 using a switching control signal, the control switching unit 27 may switch the speed command input to the speed control unit 28 by referring to the control information stored in the control information storage unit 21 for each unit control.

[0025] The speed control unit 28 generates a current command based on the input first speed command or second speed command. Specifically, the speed control unit 28 generates a current command based on the speed command received from the control switching unit 27 and outputs the generated current command to the current control unit 29. The speed control unit 28 may generate the current command by feedback control such as proportional control, integral control, proportional-integral control, or PID control according to the difference between the speed command and the speed indicated by the encoder feedback signal. The speed control unit 28 may also be able to set a specified value from among a plurality of control gains.

[0026] The current control unit 29 controls the current for driving the motor 3 based on the current command received from the speed control unit 28. For example, the current control unit 29 includes a converter circuit that converts AC power into DC power, or an inverter circuit that converts DC power into a desired AC voltage command, and performs PWM (Pulse Width Modulation) control based on the current command to supply a current according to the current command to the motor 3.

[0027] The motor control device 2 of this embodiment stores control information in the control information storage unit 21 and uses the stored control information to perform position control and pressure control of the motor 3, so it can switch between position control and pressure control of the motor 3 without relying on the calculation cycle or communication cycle of the external device 1. Generally, the control cycle within the motor control device 2 is shorter, so the control meters for position control and pressure control can be reflected quickly and the motor 3 can be controlled swiftly. This also reduces shock when switching control of the motor 3.

[0028] Note that Figure 1 is just one example, and the motor control device 2 is only required to have a control information storage unit 21 and a control system corresponding to each of the first control and the second control, and be configured to be able to switch between the first control and the second control, and the configuration of the control system is not limited to the example shown in Figure 1.

[0029] Fig. 2 is a diagram showing an example of pressurization using the motor 3 of the embodiment. In the example shown in Fig. 2, a ball screw 7, which is a mechanical drive unit for converting the rotational motion of the motor 3 into translational motion, is provided on the rotation shaft of the motor 3. A pressurization head 5 is connected to the ball screw 7, and the pressurization head 5 moves downward in the plane of the drawing and comes into contact with a workpiece 8 placed on a table 9, thereby realizing pressurization processing of the workpiece 8.

[0030] For example, the pressure head 5 is initially positioned at a certain distance from the workpiece 8, and after a feed operation in which the pressure head 5 approaches the workpiece 8, pressure is applied to the workpiece 8, thereby realizing pressure processing of the workpiece 8. Note that Fig. 2 is an example, and the configuration of the pressure mechanism driven by the motor 3, the configuration of the mechanism moved by the motor 3, etc. are not limited to the example shown in Fig. 2, depending on the type of processing.

[0031] Next, the operation of this embodiment will be described. Figure 3 is a flowchart showing an example of a motor control processing procedure in the motor control device 2 of this embodiment. As shown in Figure 3, the motor control device 2 acquires control information (step S1) and stores the control information (step S2). In detail, the control information acquisition unit 20 acquires the control information by receiving the control information from the external device 1 or by accepting input of the control information from a user, and stores the control information in the control information storage unit 21. Note that, as described above, the control information may be stored in advance in the control information storage unit 21, in which case steps S1 and S2 do not need to be performed.

[0032] The motor control device 2 determines whether to start control (step S3). In detail, for example, the command determination unit 22 determines whether a start signal has been received from the external device 1, and determines to start control when the start signal has been received. Note that the determination of whether to start control is not limited to a determination using the start signal from the external device 1. For example, the command determination unit 22 may receive an input of an instruction to start control from a user, and function as an input means such as a switch or button for receiving input, and determine to start control when the command determination unit 22 receives an input of an instruction to start control from the user. Alternatively, the command determination unit 22 may determine to start control when the command determination unit 22 receives an input of an instruction to start control from a user via an input means (not shown).

[0033] If control is not to be started (step S3: No), the motor control device 2 repeats step S3. If control is to be started (step S3: Yes), the motor control device 2 reads control information for one unit control (step S4). Specifically, the command determination unit 22 reads control information for one unit control from the control information stored in the control information storage unit 21. Note that the command determination unit 22 is not limited to this. Alternatively, the command determination unit 22 may read two sets of control information, one for the unit control to be executed most recently and the other for the next unit control, from the control information storage unit 21, and then obtain the control information for one of the sets. As described above, a series of controls is composed of two or more unit controls, and the same control parameters are used in each unit control. As described above, the control information includes order information indicating the order, and the command determination unit 22 reads the control information in accordance with the order indicated by the order information. For example, in the first step S3 after receiving the start signal, the command determination unit 22 refers to the control information corresponding to the unit control to be executed first. In the second step S3, the command determination unit 22 refers to the control information corresponding to the unit control to be executed second.

[0034] Here, the control information of this embodiment will be described. Fig. 4 is a diagram showing an example of the control information of this embodiment. In the example shown in Fig. 4, position control information and pressure control information are stored as one piece of control information in the control information storage unit 21. In the example shown in Fig. 4, the control information is in a table format, and order information is also included in this control information.

[0035] In Fig. 4, the unhatched portions indicate information related to position control, and the hatched portions indicate information related to pressure control. In the control information shown in Fig. 4, one row indicates one set of control information corresponding to one unit control, and the columns indicate control parameters (types of control parameters) that make up the control information. In the example shown in Fig. 4, one item, i.e., one column, is shared by position control information and pressure control information, and as shown at the top of the table, the control parameters indicated by each column are defined for position control and pressure control, respectively. In Fig. 4, each row of information (one set of information) shown as information set 31 is for one unit control, i.e., one set of position control information, and each row of information shown as information set 32 ​​is for one unit control, i.e., one set of pressure control information.

[0036] In the example shown in FIG. 4 , the control information includes a number that identifies each group of control information, position data / pressure command, motor speed / speed limit value, acceleration time constant / pressure holding time, deceleration time constant / pressure command time constant, position control selection / pressure control selection, and position control gain selection / pressure control gain selection. The position data / pressure command, motor speed / speed limit value, acceleration time constant / pressure holding time, and deceleration time constant / pressure command time constant are control parameters used in the processing of the position command generator 23, pressure command generator 24, position control unit 25, or pressure control unit 26, i.e., in position control or pressure control. The position data indicates a switching condition under which position control is switched to pressure control. In the example shown in FIG. 4 , when the position of the motor 3 reaches P1, position control is switched to pressure control. The switching condition is generally expressed in the format where item A becomes value B. Item A is an item (control parameter) used as the switching condition. For example, in the example shown in Fig. 4, with regard to the condition for switching from position control to pressure control, item A is the position of the motor 3, i.e., position data, and value B is P1. In the example shown in Fig. 4, value B corresponding to item A is included in the control information. In this way, the control information may include information indicating the condition for switching from position control to pressure control.

[0037] Furthermore, information specifying an item used as a switching condition (item A described above), i.e., information indicating the item used as a switching condition, may be included in the control information as determination item information. For example, a column of determination item information may be added to the table shown in FIG. 4 , and information specifying an item used as a switching condition may be stored in the column of determination item information in each row. For example, if the determination item information is 1, item A is position data, and if the determination item information is 2, item A is pressure retention time. However, the method of expressing the determination item information is not limited to this.

[0038] 4, information specifying item A for each type of operation or for each combination of the type of operation before switching and the type of operation after switching may be stored as determination item information in the control information storage unit 21. Items used as switching conditions include, for example, the position (position data) of the motor 3 and the pressure retention time, but are not limited to these, and may also be pressure (pressure feedback), speed (rotational speed) of the motor 3, time (length of time for control), or other items.

[0039] As described above, the switching conditions may be specified by the judgment item information and the data (values) of the items specified by the judgment item information. The judgment item information and the data of the items specified by the judgment item information are an example of information indicating the switching conditions. The information indicating the switching conditions is not limited to this example, and may be stored in the control information storage unit 21 separately from the table shown in FIG. 4. Furthermore, the switching conditions are not limited to conditions expressed in the format that item A becomes value B, and it is sufficient that the information indicating the switching conditions is set according to the format of the condition.

[0040] The position control selection / pressure control selection in the sixth column from the left of the control information shown in Fig. 4 is control selection information that indicates whether the unit control indicated in that row is position control or pressure control. Also, in the example shown in Fig. 4, the control selection information not only indicates whether the corresponding unit control is position control or pressure control, but also indicates the type of operation performed in the corresponding unit control.

[0041] In the example shown in FIG. 4 , pressure control operations are subdivided into three: feed operation, pressure holding operation, and pressure release operation. Also, in the example shown in FIG. 4 , position control operations are subdivided according to whether a series of operations is completed after the end of the position control corresponding to that row. For example, in the example shown in FIG. 4 , 1, 2, and 3 indicate feed operation, pressure holding operation, and pressure release operation, respectively, and 10 and 12 indicate position control. Also, 10 indicates that the operation in the next row (No. 2 in the example shown in FIG. 4 ) is performed after the corresponding position control, and 12 indicates that a series of operations is completed after the corresponding position control, i.e., there is no subsequent operation. Note that while FIG. 4 provides descriptions of operations in parentheses for ease of understanding, the control selection information does not require descriptions in parentheses and only requires numerical values. Note that FIG. 4 illustrates an example in which pressure control operations are subdivided into feed operation, pressure holding operation, and pressure release operation. However, if there is only one type of pressure control operation, the pressure control operation does not need to be subdivided.

[0042] In addition, in the example shown in FIG. 4 , the position control is subdivided and whether or not a series of operations (controls corresponding to the series of operations) is completed after the position control is completed is indicated. However, this is not limited to this. A value indicating completion may be defined as control selection information, and a line No. 7 may be added to the end of the control information shown in FIG. 4 , and the value indicating completion may be stored in the control selection information. In this case, other information in this line may not be stored, and any value may be stored. Furthermore, the completion of the series of operations may be indicated by the external device 1 by transmitting a completion signal from the external device 1. Alternatively, the control information may include information indicating the number of unit controls to be executed, or the number of unit controls to be executed may be predetermined in the control information, and the command determination unit 22 may determine the completion of the series of operations by counting the number of unit controls executed.

[0043] The above-mentioned determination item information may be included in the information stored in the position control selection / pressure control selection field. In the example shown in FIG. 4, the position control selection / pressure control selection column stores control selection information indicating whether the control is position control or pressure control, but this is not limiting. For example, the information stored in this column may be selection information including both control selection information and determination item information. For example, the selection information may be defined as a hexadecimal number of two or more digits from 0 to F, with the first digit being the control selection information and the second digit being the determination item information. In more detail, for example, X １ , X ２ are expressed as hexadecimal numbers, and the selection information is X ２ X １ and the first digit X １ is the control selection information, and the second digit X ２ may be used as the judgment item information. For example, when the judgment item information is 1, it indicates that position data is specified as the selection condition, and when the judgment item information is 2, it indicates that holding pressure information is specified as the selection condition. In this way, the content of the judgment item information corresponding to each numerical value is predefined. Note that the selection information may be three or more digits, and in this case, the third and subsequent digits may be information indicating content other than the switching condition. Also, which digits in the selection information are used as control selection information and which digits are used as judgment item information are not limited to the above example. Also, the selection information is not limited to the example expressed in hexadecimal notation.

[0044] 4, the position control gain selection / pressure control gain selection in the seventh column from the left of the control information is information indicating the position control gain, i.e., information specifying the position control gain set in position control unit 25, and in the case of pressure control, is information indicating the pressure control gain, i.e., information specifying the pressure control gain set in pressure control unit 26. Although not shown in FIG. 4, the speed control gain, which is the control gain in speed control unit 28, may also be included in the control information to specify the speed control gain.

[0045] In the example shown in FIG. 4 , the order of each row in the table format, i.e., the numbers written in the number column, is sequence information indicating the execution order of each unit control in a series of controls for executing a series of operations. Therefore, in the example shown in FIG. 4 , control is performed in the order of No. 1 → No. 2 → No. 3 → No. 4 → No. 5 → No. 6. Note that the control information shown in FIG. 4 is an example, and the specific types of control parameters used in position control or pressure control, the execution order, the types of operations in the control selection information, and the specific content of the control selection information are not limited to the example shown in FIG. 4 . The sequence information is also not limited to the example indicated by numbers. Furthermore, although numbers are assigned to each row in FIG. 4 , the order of the rows indicates the order, and a number column may not be provided. In this case, the order of the rows is sequence information indicating the order.

[0046] While FIG. 4 illustrates an example in which controls are executed in numerical order, it is also possible to set the control selection information to execute the same control again after execution is complete, or to return to a specified control and execute the process from the specified control again. For example, if the control selection information is 14, it is possible to define that one unit control process is executed twice, and to execute the same control again by specifying 14 as the control selection information. Furthermore, if the control selection information is 15, it is possible to define that Nos. 2 to 5 are executed again, and by setting the control selection information for No. 6 in the control information shown in FIG. 4 to 15, it is possible to execute Nos. 2 to 5 again after No. 6. In this case, by adding a line with No. 7 and control selection information set to 12 to the control information, No. 7 is executed after Nos. 2 to 5 are executed a second time, completing the series of operations.

[0047] In the example shown in FIG. 4 , the control information is in a table format consisting of rows and columns, but the format of the control information is not limited to a table format. For example, the control information may be represented by an algorithm such as a flowchart, or by a calculation formula. In the example shown in FIG. 4 , the position control information and the pressure control information are stored in the control information storage unit 21 as a single piece of control information. However, as described below, the position control information and the pressure control information may be stored separately in the control information storage unit 21. The contents of each item shown in FIG. 4 are merely examples, and information not shown in FIG. 4 may be included in the control information, or some items shown in FIG. 4 may not be included in the control information. In addition, the same item, i.e., information stored in one column of the table shown in FIG. 4 , can be set separately for position control and pressure control, with the exception of the control designation information. In other words, information corresponding to the same column does not necessarily have to be related to each other in position control and pressure control. In addition, the number of control information may differ between position control and pressure control. In this case, the number of columns in the table is adjusted to match the control with the larger amount of information, and some columns are not used for the control with the smaller amount of information. Furthermore, once the control information is stored in the control information storage unit 21, some or all of the control information may be changed in response to an input from the user or an instruction from the external device 1.

[0048] In the example shown in FIG. 4 , the position control information and the pressure control information are combined into one control information, thereby reducing the amount of memory used by the control information storage unit 21 compared to when separate areas are allocated for storing the position control information and the pressure control information. Furthermore, in the example shown in FIG. 4 , the control information is represented as a table consisting of rows and columns, and the columns of the table are shared, with the same columns having two meanings: an item of position control information and an item of pressure control information. The position control information and the pressure control information each include control selection information indicating whether the information corresponds to position control or pressure control. This allows both position control information (information on one item of the position control information) and pressure control information (information on one item of the pressure control information) to be stored in a single column. One row of the table stores one set of position control information or one set of pressure control information corresponding to one unit control. In this way, the amount of memory used for overhead can be reduced compared to when the position control information and the pressure control information are stored separately as tables.

[0049] Furthermore, by including the order information in the same table, memory usage can be reduced compared to allocating a separate area for the order information. In the example shown in FIG. 4 , since execution is generally performed in order from top to bottom of the table, the order information is indicated by the row-wise arrangement of each set of information (position control information or pressure control information) in the control information. As described above, the control selection information stored in the position control selection / pressure control selection column may specify the subsequent control. That is, the control selection information may include order information. For example, the control selection information may include, as order information, information indicating a row corresponding to a control to be executed after a control based on a set of information corresponding to the control selection information has been performed.

[0050] Furthermore, as shown in the example of FIG. 4 , by including a switching condition from position control to pressure control in the control information, the motor control device 2 can automatically switch from position control to pressure control without relying on information from the external device 1, even if the switching condition from position control to pressure control is defined. Similarly, when the switching condition from pressure control to position control is defined, the switching condition (information indicating the switching condition) may be included in the control information. Furthermore, when the period during which pressure control is performed is divided into multiple unit controls, the switching condition for each unit control may be included in the control information. For example, as described above, the position control selection / pressure control selection item in the control information displayed in table format may include judgment item information, and for each row, the control parameter corresponding to the judgment item information may be included in the information for that row (one set of information). Similarly, when the period during which position control is performed is divided into multiple unit controls, the switching condition for each unit control may be included in the control information. This prevents delays in the switching timing without being affected by the calculation cycle or communication cycle of the external device 1. Therefore, the motor control device 2 can reduce shock when switching from position control to pressure control.

[0051] Furthermore, as shown in the example of FIG. 4 , the control information may include a control gain. That is, the position control information may include information specifying a control gain for position control, and the pressure control information may include information specifying a control gain for pressure control. This allows the motor control device 2 to set a control gain according to each unit control. Including a control gain in the control information allows the control gain to be set in conjunction with switching from position control to pressure control, thereby enabling fine control when switching from position control to pressure control and further reducing shock when switching from position control to pressure control. If the control gain is set to a constant value, the gain value is set low in situations where vibration is likely to occur during pressure control operation. In this embodiment, by selecting and setting multiple gains, an appropriate control gain can be set according to the situation. In particular, when the workpiece 8 and the pressure head 5 change from non-contact to contact, in addition to the shock caused by contact, vibration of the pressure head 5 itself depending on the control performance is added. By appropriately setting the gain, vibration of the pressure head 5 itself can be suppressed while tracking the pressure command according to the pressure feedback, and shock reduction is expected when switching the control gain.

[0052] Furthermore, even when the workpiece 8 changes, such as when the workpiece 8 deforms, fine adjustments can be made by setting the control gain for each unit control, allowing the accuracy of pressure control to be maintained. For example, the workpiece 8 may be physically deformed when the pressure head 5 presses against it during pressure control. When the workpiece 8 deforms, the pressure feedback changes. However, by setting the control gain for following the pressure command according to the expected deformation, the motor control device 2 can perform control that quickly follows the pressure command even when the pressure feedback changes. Note that increasing the gain too much can cause vibrations, but by being able to set the control gain according to the characteristics of the workpiece 8, the motor control device 2 can achieve control that quickly follows the pressure command while suppressing the occurrence of vibrations.

[0053] Returning to the explanation of Fig. 3, when the control information shown in Fig. 4 is used, for example, the command determination unit 22 reads out one row of control information as one unit control in step S4. As described above, in the example shown in Fig. 4, since the numbers indicate the execution order, the control information of the row numbered 1 is read out in the first step S4.

[0054] Next, motor control device 2 determines whether there is an instruction to execute pressure control (step S5). Specifically, for example, command determination unit 22 determines whether the control instructed by the control information read in step S4 is pressure control or position control based on the control information. When the control information shown in FIG. 4 is used, command determination unit 22 references the control selection information stored in the position control selection / pressure control selection column to determine whether the instructed control is pressure control or position control.

[0055] If the instruction is not to execute pressure control (No in step S5), i.e., if the instruction is to execute position control, motor control device 2 executes position control (step S6). Specifically, command determination unit 22 outputs the read control information to position command generation unit 23, generates a switching control signal that instructs control switch unit 27 to select the first speed command output from position control unit 25 and output it to speed control unit 28, and outputs the generated switching control signal to control switch unit 27. This causes position command generation unit 23 and position control unit 25 to operate, the first speed command generated by position control unit 25 is output to speed control unit 28, speed control unit 28 generates a current command using the first speed command, and current control unit 29 controls the current supplied to motor 3 based on the current command.

[0056] The motor control device 2 determines whether to terminate the unit control (step S7). Specifically, the command determination unit 22 determines whether the conditions for terminating the unit control are met. For example, when the control information shown in FIG. 4 is used, the condition for switching from position control to pressure control is specified as position data, and the command determination unit 22 uses the encoder feedback signal and the position data to determine whether the switching condition is met. Alternatively, when the duration of the unit control is set, the motor control device 2 may determine whether the elapsed time since the start of the unit control has reached the set measurement time. If the unit control is not to be terminated (step S7 No), the motor control device 2 continues the position control of step S6 as the unit control.

[0057] If the unit control is to be ended (step S7: Yes), the motor control device 2 determines whether or not to complete the control (step S10). If the control is to be completed (step S10: Yes), the motor control device 2 ends the control process for the series of operations. For example, in step S10, the command determination unit 22 determines whether or not to complete the control based on the control information. When the control information shown in FIG. 4 is used, the command determination unit 22 determines that the control is to be completed when the control selection information is a value indicating that the control will be completed after the corresponding unit control is ended, i.e., when the control selection information is 12. Note that, as described above, the method for determining completion is not limited to this example. For example, a completion signal may be sent from the external device 1, or the completion may be determined by determining the number of unit controls to be executed.

[0058] If the control is not to be completed (No in step S10), the motor control device 2 repeats the process from step S4. For example, if the control information shown in FIG. 4 is used, in the second step S4, the command determination unit 22 reads out the control information No. 2.

[0059] If step S5 is Yes, motor control device 2 executes pressure control (step S8). Specifically, command determination unit 22 outputs the read control information to pressure command generation unit 24, generates a switching control signal instructing control switch unit 27 to select the second speed command output from pressure control unit 26 and output it to speed control unit 28, and outputs the generated switching control signal to control switch unit 27. This causes pressure command generation unit 24 and pressure control unit 26 to operate, the second speed command generated by pressure control unit 26 is output to speed control unit 28, speed control unit 28 generates a current command using the second speed command, and current control unit 29 controls the current supplied to motor 3 based on the current command.

[0060] The motor control device 2 determines whether to end the unit control (step S9). Specifically, the command determination unit 22 determines whether the conditions for ending the unit control are met. For example, when the control information shown in FIG. 4 is used, a pressure-holding time is set for the pressure-holding operation of the pressure control, and therefore, whether to end the unit control is determined based on whether the elapsed time since the start of the pressure-holding operation has reached the pressure-holding time. If the unit control is not to be ended (step S9: No), the motor control device 2 continues the pressure control of step S8 as the unit control. If the unit control is to be ended (step S9: Yes), the motor control device 2 proceeds to step S10.

[0061] Next, a specific example of the control performed by the motor control device 2 will be described. FIG. 5 is a diagram showing an example of a series of operations according to an embodiment. FIG. 5 shows an example of operations performed based on the control information shown in FIG. 4. The upper part of FIG. 5 shows an image diagram illustrating the operations of the motor 3 and the pressure head 5 in a simplified manner. In FIG. 5, only some parts are labeled for simplification. The open arrows at the top of FIG. 5 indicate the movement of the pressure head 5, and the black hatched arrows indicate the application of pressure to the workpiece 8 by the pressure head 5. The first row at the bottom of FIG. 5 shows the motor speed, which is the speed of the motor 3. The second row at the bottom of FIG. 5 shows the gains (position control gain, pressure control gain). The third row at the bottom of FIG. 5 shows the pressure command and pressure feedback (the value detected by the pressure sensor 6). The horizontal axis indicates time.

[0062] As shown in Figures 4 and 5, position control is performed first as unit control No. 1. Here, position data is specified as the judgment item information when switching from position control, which is unit control No. 1, to pressure control, which is unit control No. 2. In position control No. 1, the position data, which is the control parameter corresponding to the judgment item information, is P1 in the control information shown in Figure 4, so the motor control device 2 drives motor 3 by position control to lower the pressure head 5 until the position of motor 3 reaches P1. At this time, the gain (position control gain) in position control unit 25 is set to G1.

[0063] When the switching condition is satisfied, the motor control device 2 reads the control information No. 2 and executes the pressure-controlled feed operation as the No. 2 unit control. During the No. 2 unit control period, the speed limit value is set to V2, so the motor speed is controlled to be equal to or less than V2. The feed operation transitions the workpiece 8 and the pressure head 5 from a non-contact state to a contact state. The pressure command value indicated by the dashed line in the third row of FIG. 5 is set to PN1, and the gain (pressure control gain) in the pressure control unit 26 is set to G2. Although the pressure command value is set to PN1, actual pressure application does not begin during the feed operation. In the examples shown in FIGS. 4 and 5, the condition for ending the feed operation—i.e., the condition for switching from the feed operation to the next unit control—is specified by position data. The position data for this switching condition may be specified separately from the table shown in FIG. 4 or may be included in a table indicating control information, not shown in FIG. 4.

[0064] When the conditions for ending the feed operation are satisfied, the motor control device 2 reads the control information for No. 3 and executes a pressure control dwelling operation as the unit control for No. 3. In the example shown in FIGS. 4 and 5, the end conditions for the dwelling operations for No. 3 and No. 4, i.e., the conditions for switching from the dwelling operations for No. 3 and No. 4 to the next unit control, are specified by the dwelling time. During the unit control for No. 3, the dwelling time is set to T1, so the motor control device 2 executes the dwelling operation for the time T1. Furthermore, the command value of the pressure command is set to PN1, as in No. 2, and the pressure feedback is controlled to PN1. Furthermore, the gain (pressure control gain) in the pressure control unit 26 is set to G3.

[0065] Next, as unit control No. 4, pressure control continues with a pressure holding operation. During unit control No. 4, the pressure holding time is set to T2, so the motor control device 2 performs the pressure holding operation for the time T2. The pressure command value is set to PN2, and the pressure feedback is controlled to PN2. The gain (pressure control gain) in the pressure control unit 26 is set to G4. In this way, by changing the gain values ​​set for No. 3 and No. 4, it is possible to change the gain during the pressure holding operation depending on the pressure holding time. In this embodiment, the control gain can be precisely set using the control information, thereby reducing the shock when switching from position control to pressure control.

[0066] Next, a pressure control depressurization operation is performed as unit control No. 5. In the example shown in Figures 4 and 5, the end condition of the depressurization operation No. 5, i.e., the condition for switching from the depressurization operation No. 5 to position control No. 6, is specified by pressure (pressure feedback). Therefore, the depressurization operation is performed until the pressure feedback becomes PN3 or less. In addition, the gain (pressure control gain) in the pressure control unit 26 is set to G5. In the depressurization operation, the workpiece 8 and pressure head 5 transition from a contacting state to a non-contacting state.

[0067] Next, position control is performed as unit control No. 6. This position control is performed until the position of the motor 3 reaches P2. The gain (position control gain) in the position control unit 25 is set to G6.

[0068] As described above, the motor control device 2 of this embodiment can automatically switch between position control and pressure control using stored control information. This makes it possible to reduce shock when switching control of the motor 3 without being affected by the calculation cycle or communication cycle of the external device 1.

[0069] Next, another example of control information will be described. FIG. 6 is a diagram showing another example of control information in an embodiment in which a sequence from a feed operation to a depressurization operation is repeated twice. The example shown in FIG. 6 shows an example of control information in which a sequence from a feed operation to a depressurization operation is repeated twice. In the example shown in FIG. 6, information sets 31 for Nos. 1, 5, and 9 are position control information, and information sets 32 for Nos. 2 to 4 and Nos. 6 to 8 are pressure control information. The control information for each of Nos. 6 to 8 is the same as the control information for each of Nos. 2 to 4. As a result, the operations corresponding to Nos. 6 to 8 are the same as the operations corresponding to Nos. 2 to 4, and the sequence from a feed operation to a depressurization operation is repeated twice. In Fig. 6, when the same operation is repeated, multiple sets of control information corresponding to the operation to be repeated are stored in the control information table. However, this is not limited to this. The table may store one set of control information corresponding to the operation to be repeated, and the operation may be repeated by specifying the next number to be executed by setting the control selection information, as described above. For example, the control selection information for row No. 5 in Fig. 6 may store a value indicating that after No. 5 is executed, Nos. 2 to 4 are repeated, and if Nos. 2 to 4 have been executed twice, the series of operations is completed after No. 5 is executed, and the control information may only contain information from Nos. 1 to 5.

[0070] 7 is a diagram showing an example of control information in an embodiment in which position control information and pressure control information are stored separately. In the example shown in FIG. 7, the position control information and pressure control information are each stored separately in table format in the control information storage unit 21. Note that the format of the position control information and pressure control information is not limited to the table format.

[0071] In the example shown in FIG. 7 , the control information includes position control information, pressure control information, and sequence information. For example, in the sequence information, a is added to the number corresponding to each set of information in the position control information, and b is added to the number corresponding to each set of information in the pressure control information, thereby identifying whether the information indicates position control information or pressure control information. For example, a1 indicates No. 1 in the position control information. In the example shown in FIG. 7 , the sequence information is defined to execute the control in the order of a1, b1, b2, b3, b4, a2, b5, b6, b7, and a3. Therefore, first, the position control corresponding to No. 1 in the position control information is performed, followed by the pressure control corresponding to No. 1 to No. 4 in the pressure control information. Next, the position control corresponding to No. 2 in the position control information is performed, followed by the pressure control corresponding to No. 5 to No. 7 in the pressure control information, and finally the position control corresponding to No. 3 in the position control information.

[0072] In step S4 described above, the command determination unit 22 reads out the corresponding number information from the position control information or the pressure control information based on the order information. Note that the order information shown in FIG. 7 does not necessarily use a or b to identify the position control information and the pressure control information. For example, Nos. 1 to 20 may be designated as position control numbers, and Nos. 21 and onward may be designated as pressure control numbers, and the position control information and the pressure control information may be assigned numbers according to this rule. Furthermore, if no order instruction is given, the control corresponding to the next number in the same control information is performed, and when switching between position control and pressure control, the control corresponding to the number following the previously performed control is performed. The order information may specify a number corresponding to the control to be performed at the start of a series of controls and a number for the control to which position control and pressure control will switch after the execution of that unit control. For example, when controls are performed in the order shown in FIG. 7, the order information specifies a1 as the first control to be performed, and a1, b4, a2, and b7 as the switching numbers. The above-described methods of specifying the order in the order information are merely examples, and the method of specifying the order in the order information is not limited to these examples.

[0073] The control selection column shown in FIG. 7 stores control selection information indicating the type of control in position control or the type of control in pressure control. In the example shown in FIG. 7, the order information is provided separately from the position control information and the pressure control information, but the order information may also be included in the position control information and the pressure control information. For example, an order information column may be added to each of the position control information and the pressure control information, and a number corresponding to the control to be executed after the control corresponding to that row is completed may be stored. For example, by storing a value indicating the pressure control information No. 1 as the order information corresponding to the position control information No. 1, the pressure control information No. 1 is executed after the control corresponding to the position control information No. 1. Similarly, by storing information indicating the next control to be executed as the order information for each row, the execution order of unit controls in a series of operations including both position control and pressure control can be set to a desired order. Furthermore, if order information is not specified, i.e., if the order information is left blank, the control with the next number in the same control information may be executed after the corresponding unit control is completed. The control selection column shown in FIG. 7 may also be used as the order information column, and information indicating the next control to be executed may be stored in this column. 6 and 7 are merely examples, and as described with reference to FIG. 4, the information included in the position control information and pressure control information is not limited to these examples.

[0074] Furthermore, in the above example, position control is performed as the first control. However, if speed control, torque control, or other control other than position control is performed as the first control, speed control information used for speed control and torque control information used for torque control are stored in the control information storage unit 21 instead of the position control information. This allows control to be performed without being affected by the calculation cycle or communication cycle of the external device 1, thereby reducing shock when switching between speed control or torque control and pressure control. Note that if switching conditions between speed control or torque control and pressure control are defined, the switching conditions are also included in the control information. Furthermore, if two of position control, speed control, and torque control are performed as the first control, similarly, by storing the respective control information in the control information storage unit 21, the motor control device 2 can automatically switch between the control modes without being affected by the calculation cycle or communication cycle of the external device 1.

[0075] Next, the hardware configuration of the motor control device 2 of this embodiment will be described. At least some of the components constituting the motor control device 2 shown in FIG. 1 are implemented, for example, by a processing circuit. The processing circuit may be a dedicated circuit such as an FPGA (Field-Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit), or may be a control circuit equipped with a processor. Furthermore, at least some of the components constituting the motor control device 2 may be implemented by a combination of a dedicated processing circuit and a control circuit. Furthermore, at least some of the components constituting the motor control device 2 may be implemented by both a processing circuit and hardware such as a switching circuit.

[0076] For example, at least some of the command determination unit 22, position command generation unit 23, pressure command generation unit 24, position control unit 25, pressure control unit 26, control switching unit 27, speed control unit 28, and current control unit 29 shown in FIG. 1 are realized by a processing circuit.

[0077] 8 is a diagram showing an example of a control circuit. When a processing unit, which is at least a part of the components constituting the motor control device 2, is implemented by a control circuit, the function of the processing unit is realized by the processor 101 executing a program for implementing the operation of the target component, which is stored in memory 102. The processor 101 includes, for example, a CPU (Central Processing Unit, also referred to as a central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, or DSP (Digital Signal Processor)) or a system LSI (Large Scale Integration). The memory 102 includes, for example, a RAM (Random Access Memory) and a ROM (Read Only Memory).

[0078] When the processor 101 executes the program, the memory 102 is also used. The program may be provided by a recording medium or a communication medium. The control circuit is an example of a computer system, and the program can be said to be a program that causes the computer system to execute each process performed by the processing unit. Furthermore, the control information storage unit 21 shown in FIG. 1 may be part of the memory 102, or may be realized by a memory provided separately from the memory 102. Furthermore, the processing unit may be realized by multiple control circuits.

[0079] Furthermore, when the control information acquisition unit 20 accepts input from a user, the control information acquisition unit 20 is realized by an input unit such as a touch panel or a keyboard, and when the control information acquisition unit 20 receives control information from the external device 1, the control information acquisition unit 20 is realized by a communication unit including a transmitter and a receiver. Furthermore, the control information acquisition unit 20 may be realized by both an input unit and a communication unit. Furthermore, when the control information acquisition unit 20 receives control information from an external input unit, the control information acquisition unit 20 is realized by a communication unit or an input interface circuit that receives control information from the input unit.

[0080] Furthermore, when the command determination unit 22 receives a start signal from the external device 1, a communication unit is also used to implement the command determination unit 22. Alternatively, a communication unit may be used separately from the command determination unit 22, and the command determination unit 22 may receive the start signal from the external device 1 via the communication unit. This communication unit may be the same as the communication unit that receives the control information. Furthermore, when the command determination unit 22 receives an instruction to start control from a user, input means such as a button, switch, or touch panel are also used to implement the command determination unit 22. Furthermore, when the command determination unit 22 receives an instruction to start control from external input means, a communication unit or an input interface circuit that receives the instruction from the input means is also used to implement the command determination unit 22.

[0081] As described above, in this embodiment, the motor control device 2 stores control information including first control information used for the first control, second control information used for the second control, and sequence information indicating the sequence of execution of the unit controls, and uses the stored control information to control the motor 3. This reduces shock when switching the control of the motor 3.

[0082] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or different embodiments may be combined with each other. It is also possible to omit or modify parts of the configurations as long as they do not deviate from the gist of the invention.

[0083] 1 External device, 2 Motor control device, 3 Motor, 4 Encoder, 5 Pressure head, 6 Pressure sensor, 7 Ball screw, 8 Workpiece, 9 Table, 20 Control information acquisition unit, 21 Control information storage unit, 22 Command determination unit, 23 Position command generation unit, 24 Pressure command generation unit, 25 Position control unit, 26 Pressure control unit, 27 Control switching unit, 28 Speed ​​control unit, 29 Current control unit, 30 Motor control unit, 31, 32 Information set, 100 Motor control system.

Claims

1. A motor control device capable of executing pressure control, which is control of a motor based on a pressure command, and first control, which is control of the motor based on a first command that is a command other than the pressure command, comprising: a control information storage unit that stores control information including first control information used to generate the first command, second control information used to generate the pressure command, and sequence information that indicates the sequence of execution of the first control and the second control, which is the pressure control; and a motor control unit that controls the motor based on the control information.

2. A motor control device as described in claim 1, characterized in that a series of operations of the motor is controlled by a series of controls including a plurality of unit controls, one of the unit controls is the first control or the second control, one of the unit controls uses one set of the first control information or one set of the second control information, and the sequence information indicates the sequence of execution of the unit controls.

3. A motor control device as described in claim 1 or 2, characterized in that the control information storage unit stores the first control information, the second control information, and the sequence information as one piece of control information.

4. The motor control device described in claim 2, characterized in that the control information is in tabular form represented as a table consisting of rows and columns, and in the table, items corresponding to one column are defined by the first control information and the second control information, and one row of the table stores one set of the first control information or one set of the second control information corresponding to one unit control, and the first control information and the second control information include control selection information indicating whether the information corresponds to the first control or the second control.

5. The motor control device according to claim 4, wherein the sequence information is indicated by the row-wise arrangement order of the information of each set in the control information.

6. A motor control device as described in claim 4, characterized in that the control selection information includes, as the sequence information, information indicating a row corresponding to the control to be executed after control based on a set of the information corresponding to the control selection information has been performed.

7. The motor control device according to claim 1 or 2, characterized in that the control information storage unit stores the first control information, the second control information, and the sequence information individually.

8. The motor control device according to any one of claims 1 to 7, wherein the control information includes information indicating a condition for switching from the first control to the second control.

9. A motor control device as described in any one of claims 1 to 8, characterized in that the first control information includes information specifying a control gain in the first control, and the second control information includes information specifying a control gain in the second control.

10. The motor control device according to any one of claims 1 to 9, wherein the first control includes at least one of position control, speed control, and torque control.

11. The motor control device according to claim 10, characterized in that the motor control unit comprises: a command determination unit that determines whether to generate the first command or the pressure command based on the control information; a first command generation unit that generates the first command based on the control information when the command determination unit determines to generate the first command; and a second command generation unit that generates a second command, which is the pressure command, based on the control information when the command determination unit determines to generate the pressure command.

12. The motor control device according to claim 11, wherein the first control is the position control, the torque control, or the speed control, and the motor control unit comprises: a first control unit that generates a first speed command by feedback control based on the difference between the first command and first feedback information used for the first control; a second control unit that generates a second speed command by feedback control based on the difference between the second command and feedback information of a pressure generated by driving the motor; a speed control unit that generates a current command based on the first speed command or the second speed command that is input; a control switching unit that inputs the first speed command or the second speed command to the speed control unit based on the determination result of the command determination unit; and a current control unit that supplies a current to the motor based on the current command.

13. A motor control method in a motor control device capable of executing pressure control, which is control of a motor based on a pressure command, and first control, which is control of the motor based on a first command that is a command other than the pressure command, the motor control method comprising: storing control information including first control information used to generate the first command, second control information used to generate the pressure command, and sequence information indicating the sequence of execution of the first control and pressure control; and controlling the motor based on the control information.

Images