Control device

Abstract

A control device according to the present disclosure comprises a servo control unit that controls a motor on the basis of interpolation data for commanding a movement amount for each control cycle for controlling the motor. When switching from a cutting feed mode to a fast feed mode, the servo control unit switches a gain for cutting feed to a gain for fast feed immediately before the speed of the motor reaches the maximum speed of the cutting feed, and when switching from the fast feed mode to the cutting feed mode, switches from the gain for fast feed to the gain for cutting feed immediately after the speed of the motor falls below the maximum speed of the cutting feed.

Description

control device

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

[0002] When controlling multiple motors installed in industrial machinery such as machine tools, the command speed of the cutting feed command is generally set to be slower than the command speed of the rapid traverse command, so the gain during cutting feed is set to be larger than the gain during rapid traverse, improving the tracking ability during each feed operation.

[0003] In current control methods, when the feed mode is switched between cutting feed and rapid feed, the motor temporarily decelerates and stops (see, for example, Patent Document 1). Therefore, even if the gain is switched simultaneously with the feed mode switch, there is little current step. For example, increasing the proportional gain is effective in improving tracking when switching the feed mode from rapid feed to cutting feed, but this can easily lead to the generation of vibration. On the other hand, increasing the integral gain can suppress vibration, but tracking is inferior compared to increasing the proportional gain.

[0004] Japanese Patent Application Laid-Open No. 2008-130013

[0005] Switching the gain at the same time as switching the feed mode can cause vibrations in the cutting section, which can lead to a deterioration in machining accuracy. For example, when switching from a constant speed cutting feed to a rapid feed, or when switching the feed mode from a constant speed rapid feed to a cutting feed, the change in proportional gain directly amplifies the speed step, which can lead to excessive current steps. In production sites, there is a demand for a mechanism that allows the gain to be switched when switching feed modes to prevent excessive current steps from occurring.

[0006] The control device according to the present disclosure solves the above problem by switching the gain when the speed reaches the maximum speed of the cutting movement command after the feed mode is switched.

[0007] One aspect of the present disclosure is a control device that includes a servo control unit that controls a motor based on interpolation data that commands the amount of movement for each control cycle that controls the motor, and when switching from cutting feed mode to fast feed mode, the servo control unit switches the gain for cutting feed to the gain for fast feed just before the speed of the motor reaches the maximum cutting feed speed, and when switching from fast feed mode to cutting feed mode, switches from the gain for fast feed to the gain for cutting feed just after the speed of the motor falls below the maximum cutting feed speed.

[0008] FIG. 1 is a schematic hardware configuration diagram of a control device according to a first embodiment. FIG. 2 is a block diagram showing schematic functions of a control device according to the first embodiment. FIG. 3 is a block diagram showing a schematic configuration example of a servo control unit according to the first embodiment. FIG. 4 is a block diagram showing a schematic configuration example of a speed control unit according to the first embodiment. FIG. 5 is a graph illustrating an example of a speed transition when switching from cutting feed to fast traverse. FIG. 6 is a graph illustrating an example of a speed transition when switching from fast traverse to cutting feed. FIG. 7 is a block diagram showing a schematic configuration example of a speed control unit according to a second embodiment. FIG. 8 is a graph illustrating an example of a speed transition when switching from cutting feed to fast traverse. FIG. 9 is a graph illustrating an example of a speed transition when switching from fast traverse to cutting feed.

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following description, components having the same or similar functions will be denoted by the same reference numerals. Duplicate descriptions of those components may be omitted.

[0010] In this application, "based on XX" means "based on at least XX," and includes cases where it is based on other elements in addition to XX. Furthermore, "based on XX" is not limited to cases where XX is used directly, but also includes cases where it is based on XX that has been calculated or processed. "XX" is any element (for example, any information).

[0011] First Embodiment Fig. 1 is a schematic hardware configuration diagram showing the main parts of a control device according to an embodiment of the present disclosure. The control device 1 of the present disclosure can be implemented as a motor control device that controls a motor that drives industrial machinery such as a machine tool or a robot. The control device 1 of the present disclosure can also be implemented as a numerical control device that controls industrial machinery equipped with a moving object that moves when driven by a motor, based on a numerical control program or the like. An example of implementation as a numerical control device that controls based on a numerical control program or the like will be described below.

[0012] The CPU 11 included in the control device 1 of the present disclosure is a processor that performs overall control of the control device 1. The CPU 11 reads a system program stored in the ROM 12 via the bus 22 and controls the entire control device 1 in accordance with the system program. The RAM 13 temporarily stores temporary calculation data, display data, various data input from outside, and the like.

[0013] The nonvolatile memory 14 is configured, for example, by a memory backed up by a battery (not shown) or an SSD (Solid State Drive), and retains its stored state even when the power to the control device 1 is turned off. The nonvolatile memory 14 stores operation programs and data read from an external device 72 via the interface 15, data and operation programs input via the input device 71, and various data acquired from the industrial machine 3. The operation programs and data stored in the nonvolatile memory 14 may be expanded into the RAM 13 when executed / used. Furthermore, various system programs such as known analysis programs are written in the ROM 12 in advance.

[0014] The interface 15 is an interface for connecting the CPU 11 of the control device 1 to an external device 72 such as a USB memory, CompactFlash (registered trademark), or SD card. For example, operation programs and various data used to control the industrial machine 3 can be read from the external device 72. Furthermore, operation programs and various data edited within the control device 1 can be stored in the external device 72. A PLC (programmable logic controller) 16 outputs signals to the industrial machine 3 and its peripheral devices (e.g., tool changers, actuators such as robots, sensors attached to the industrial machine 3, etc.) via an I / O unit 17 to control the industrial machine 3 using a sequence program built into the control device 1. The PLC 16 also receives signals from various switches on an operation panel installed on the main body of the industrial machine 3 and from peripheral devices, performs the necessary signal processing, and then passes the signals to the CPU 11.

[0015] The display device 70 displays various data loaded into the memory, data obtained as a result of executing operation programs, system programs, etc., output via the interface 18. In addition, the input device 71, which is composed of a keyboard, pointing device, etc., passes instructions, data, etc. based on operations by an operator to the CPU 11 via the interface 19.

[0016] The interface 20 is an interface for connecting the CPU 11 of the control device 1 to a wired or wireless network 5. The network 5 may communicate using technologies such as serial communication such as RS-485, Ethernet (registered trademark), optical communication, wireless LAN, Wi-Fi (registered trademark), Bluetooth (registered trademark), etc. Other control devices 4, fog computers 6, cloud servers 7, etc. are connected to the network 5, and data is exchanged between the network 5 and the control device 1.

[0017] The axis control circuit 30 for controlling the drive axes of the industrial machine 3 receives position commands for the drive axes from the CPU 11 and outputs commands for the drive axes to the servo amplifier 40. The servo amplifier 40 receives these commands and drives the servo motors 50 associated with the drive axes, moving each component of the industrial machine 3 along the respective axes. Each servo motor 50 has a built-in position detector, and feeds back a position feedback signal from the position detector to the axis control circuit 30. The axis control circuit 30 performs feedback control of the servo motor 50 based on the position feedback signal. Note that while only one axis control circuit 30, servo amplifier 40, and servo motor 50 are shown in the hardware configuration diagram of FIG. 1 , in reality, there are as many axis control circuits 30, servo amplifiers 40, and servo motors 50 as there are drive axes of the industrial machine 3 to be controlled. For example, to control a typical machine tool with three linear axes and two rotational axes, five sets of axis control circuits 30, servo amplifiers 40, and servo motors 50 are provided to move a spindle to which a tool is attached and a workpiece relatively in the three linear axes and two rotational axes (X-axis, Y-axis, Z-axis, A-axis, and C-axis directions).

[0018] The spindle control circuit 60 receives a spindle rotation command and outputs a spindle speed signal to a spindle amplifier 61. The spindle amplifier 61 receives this spindle speed signal and rotates a spindle motor 62 of the industrial machine 3 at the commanded rotation speed to drive the spindle. A position coder 63 is connected to the spindle motor 62. The position coder 63 outputs a feedback pulse in synchronization with the rotation of the spindle, and the feedback pulse is read by the CPU 11.

[0019] The control device 1 may be configured as a separate entity from the industrial machine 3. In this case, the control device 1 and the industrial machine 3 may be connected by a signal line or the like, or may be connected via a network. Furthermore, the control device 1 may be connected to the industrial machine 3 by being incorporated in the industrial machine 3.

[0020] 2 is a schematic block diagram illustrating functions of the control device 1 according to the first embodiment of the present disclosure. Each function of the control device 1 according to this embodiment is realized by the CPU 11 of the control device 1 shown in FIG. 1 executing a system program and controlling the operation of each part of the control device 1.

[0021] The control device 1 of this embodiment includes a program analysis unit 100, a speed control unit 110, an interpolation unit 120, and a control unit 140, and the control unit 140 includes a servo control unit 150. The RAM 13 to the nonvolatile memory 14 of the control device 1 store a control program 200, such as a numerical control program including commands for controlling the industrial machine 3, in advance.

[0022] The program analysis unit 100 sequentially reads blocks included in the control program 200 and analyzes commands related to the operation of the industrial machine 3 by the blocks. Then, based on the analysis results, it creates command data for commanding the operation of the industrial machine 3. The analysis by the program analysis unit 100 is based on parameters set in the control device 1 and the settings of the industrial machine 3. For example, if a block read from the control program 200 is a command to move a moving object of the industrial machine 3, the command data created by the program analysis unit 100 becomes data for commanding the rotational operation of the servo motor 50 related to at least one axis related to the movement. Also, for example, if a block read from the control program 200 commands the operation of the spindle motor 62, the command data becomes data for commanding the rotational operation of the spindle motor 62. The program analysis unit 100 outputs data for commanding the rotational operation of each servo motor 50 to the interpolation unit 120. In addition, it outputs command data for controlling other operations of the industrial machine 3 to the control unit 140. In addition,

[0023] The interpolation unit 120 generates interpolation data indicating the amount of movement per predetermined interpolation period (control period) for each servo motor 50 related to the movement commanded by the command data, based on the command data for the servo motors 50 generated by the program analysis unit 100. In the interpolation data generated by the interpolation unit 120, the amount of movement per interpolation period is indicated by, for example, the number of pulses. The interpolation unit 120 outputs the generated interpolation data to the servo control unit 150.

[0024] The control unit 140 controls each part of the industrial machine 3 based on the command data created by the program analysis unit 100 and the interpolation data created by the interpolation unit 120. For example, based on the command data created by the program analysis unit 100, the control unit 140 creates control commands for the spindle motor 62 provided in the industrial machine 3, signals for controlling peripheral devices, and the like, and outputs them to the industrial machine 3. The control unit 140 also acquires the state of each part of the industrial machine 3 as feedback values ​​and uses them in each control process. The control unit 140 includes a servo control unit 150 that controls the servo motor 50 provided in the industrial machine 3.

[0025] The servo control unit 150 controls the movement amount of the servo motor 50 for each interpolation period based on the interpolation data created by the interpolation unit 120. FIG. 3 is a block diagram showing a schematic configuration example of the servo control unit 150. The servo control unit 150 shown in FIG. 3 is configured as a controller that performs PI control. The servo control unit 150 receives interpolation data, which is the movement amount for each control period, from the interpolation unit 120. The servo control unit 150 includes a position control unit 151 and a speed calculation unit 153.

[0026] The position control unit 151 outputs the movement amount for each control cycle based on the difference between the movement position of the servo motor 50 calculated based on the movement amount obtained from the interpolation unit 120 and the position feedback value obtained from the servo motor 50. The position control unit 151 outputs a speed command value obtained by multiplying the position feedback value by a predetermined position gain K.

[0027] The speed control unit 152 performs proportional-integral control (PI control) to control the speed of the servo motor 50 based on a speed deviation, which is the difference between the speed command value output from the position control unit 151 and a speed feedback value calculated by the speed calculation unit 153 based on the position feedback value from the servo motor 50 for each control cycle. Fig. 4 is a block diagram showing a schematic configuration example of the speed control unit 152. The speed control unit 152 includes a proportional gain unit 154, an integral gain unit 155, and an integrator 156. The speed control unit 152 calculates a proportional gain K p and the integral gain K I The value obtained by multiplying the value by the value obtained by integrating the value by the integrator 156 is output as the speed command value.

[0028] Here, the position gain K and the proportional gain K p , integral gain K I In the fast forward mode, the position gain K _r , proportional gain K p_r , integral gain K I_r In the cutting feed mode, the position gain K _c , proportional gain K p_c , integral gain K I_c is used.

[0029] When the feed mode is switched from cutting feed to fast feed, the position control unit 151 and the speed control unit 152 according to this embodiment determine whether the speed of the servo motor 50 reaches the maximum cutting feed speed F after switching to the fast feed mode. cmax Before reaching the position gain K and proportional gain K p , integral gain K I Switch from the respective cutting feed gains to the rapid traverse gains.

[0030] 5 is a graph showing an example of the transition of speed when a switch is made from cutting feed to rapid traverse. In the graph shown in FIG. 5, the solid line indicates the cutting feed speed, and the dotted line indicates the rapid traverse speed. In the example of FIG. 5, the cutting feed speed is F c , fast forward speed is Fr Then, assume that the feed mode is switched from cutting feed to fast feed at time t1. At this time, in the past, the respective gains would be switched from the gain for cutting feed to the gain for fast feed at time t1. In the servo control unit 150 according to the present disclosure, when the feed mode is switched from the cutting feed mode to the fast feed mode, the timing is not the timing when the feed mode is switched, but when the feed speed reaches the maximum speed F of cutting feed. cmax At time t2, which is the time immediately before the position gain K and the proportional gain K p , integral gain K I to a value for the fast feed mode. This gain switching is performed, for example, when the speed of the servo motor 50 reaches the maximum cutting feed speed F cmax from a predetermined velocity variation δ F1 This should preferably be done when the vehicle reaches a speed below the specified speed.

[0031] Furthermore, when the feed mode is switched from fast forward to cutting feed, the position control unit 151 and the speed control unit 152 according to this embodiment determine whether the speed of the servo motor 50 is equal to the maximum speed F of cutting feed before the mode is switched to the cutting feed mode. cmax When the gain drops below the position gain K, the proportional gain K p , integral gain K I Switch from the respective rapid traverse gains to the cutting feed gains.

[0032] Fig. 6 is a graph illustrating the transition of speed when switching from fast forward to cutting feed. In the graph illustrated in Fig. 6, the solid line indicates the cutting feed speed, and the dotted line indicates the fast forward speed. In the example of Fig. 6, the feed mode is switched from cutting feed to fast forward at time t3. At this time, conventionally, the gains would be switched from the gain for fast forward to the gain for cutting feed at time t3. In the servo control unit 150 according to the present disclosure, when the feed mode is switched from fast forward mode to cutting feed mode, the timing when the feed speed reaches the maximum speed F of cutting feed is determined, not at the timing when the feed mode is switched. cmax At time t4, when the position gain K and the proportional gain K p , integral gain KI to a value for the cutting feed mode. This gain switching is performed, for example, when the speed of the servo motor 50 reaches the maximum cutting feed speed F cmax from a predetermined velocity variation δ F2 This should preferably be done when the vehicle reaches a speed below the specified speed.

[0033] The control device 1 according to this embodiment, which is equipped with a higher-level configuration, switches the gains after a sufficient time has passed since the cutting feed was switched to the rapid feed. Also, the gains are switched well before the rapid feed is switched to the cutting feed. Therefore, the gain switching does not affect the cutting feed operation, and the quality of the machined surface can be maintained.

[0034] Second Embodiment A control device according to a second embodiment of the present disclosure will be described below. The control device 1 according to this embodiment has the same hardware configuration as the control device 1 according to the first embodiment.

[0035] Like the control device 1 according to the first embodiment, the control device 1 according to this embodiment includes a program analysis unit 100, a speed control unit 110, an interpolation unit 120, and a control unit 140, and the control unit 140 includes a servo control unit 150. In addition, the RAM 13 to the nonvolatile memory 14 included in the control device 1 store in advance a control program 200 such as a numerical control program including commands for controlling the industrial machine 3.

[0036] The program analysis unit 100 and interpolation unit 120 according to this embodiment have the same functions as those according to the first embodiment.

[0037] The servo control unit 150 controls the movement amount of the servo motor 50 for each interpolation period based on the interpolation data created by the interpolation unit 120. Similar to the servo control unit 150 according to the first embodiment, the servo control unit 150 includes a position control unit 151, a speed control unit 152, and a speed calculation unit 153. The position control unit 151 and the speed calculation unit 153 according to this embodiment have the same functions as the position control unit 151 and the speed calculation unit 153 according to the first embodiment.

[0038] Similar to the speed control unit 152 according to the first embodiment, the speed control unit 152 performs proportional-integral control (PI control) to control the speed of the servo motor 50 based on a speed deviation, which is the difference between the speed command value output from the position control unit 151 and a speed feedback value calculated by the speed calculation unit 153 based on the position feedback value for each control cycle from the servo motor 50. The speed control unit 152 according to this embodiment differs from the speed control unit 152 according to the first embodiment in that it switches only the integral gain in stages when switching the feed mode.

[0039] 7 is a block diagram showing a schematic configuration example of the speed control unit 152 according to this embodiment. The speed control unit 152 further includes a gain switching filter 157 in addition to a proportional gain unit 154, an integral gain unit 155, and an integrator 156. Similar to the speed control unit 152 according to the first embodiment, the speed control unit 152 operates in such a way that the proportional gain unit 154 selects a proportional gain K p and the integral gain unit 155 calculates an integral gain K I The speed control unit 152 according to this embodiment integrates the integral gain value by multiplying the integral gain by the integral gain unit 155 in a stepwise manner.

[0040] 8 is a graph showing an example of the transition of integral gain when switching from cutting feed to rapid traverse. In the graph shown in FIG. 8, the solid line indicates integral gain. In the example of FIG. 8, the integral gain for cutting feed mode is K I_c , the integral gain for fast forward mode is K I_r In addition, it is assumed that the feed mode is switched from cutting feed to rapid feed at time t1. At this time, the gain switching filter 157 according to this embodiment switches the integral gain K I is the integral gain K for cutting feed mode I_c The feed rate is gradually decreased from the maximum cutting feed rate F cmax The fast forward mode integral gain K I_rThe time required for switching, t3-t2 (=time constant T), should be set to an appropriate value by conducting experiments in advance.

[0041] 9 is a graph showing an example of the transition of integral gain when switching from rapid traverse to cutting feed. In the graph shown in FIG. 9, the solid line indicates integral gain. In the example of FIG. 9, the integral gain for cutting feed mode is K I_c , the integral gain for fast forward mode is K I_r Also, assume that the feed mode is switched from fast feed to cutting feed at time t4. At this time, the gain switching filter 157 according to this embodiment detects whether the feed rate is greater than the maximum cutting feed rate F cmax After time t5, which is a predetermined time point after the integral gain K I is the integral gain K for fast forward mode I_r At a predetermined time t6 before time t4, the cutting feed mode integral gain K I_c The time required for switching, t6-t5 (=time constant T), should be set to an appropriate value by conducting experiments in advance.

[0042] The cutting feed rate F c and maximum cutting feed rate F cmax If the difference between the maximum cutting feed speed F and the maximum cutting feed speed F is small or the time constant T applied to the gain switching is long, cmax If the gain is not switched to the fast forward mode at this point, vibrations may occur during fast forward. In such cases, change the value of the time constant T applied to the gain switch to a smaller value, and make sure that the speed does not exceed the maximum cutting feed speed F. cmax It is desirable to switch to the gain for the fast forward mode before the gain exceeds .

[0043] The control device 1 according to this embodiment, which is equipped with a higher-level configuration, starts switching the integral gain after a sufficient amount of time has passed since the switch from cutting feed to fast feed, and the gain value is switched in stages by multiplying it by a predetermined time constant. Also, the control device 1 starts switching the integral gain well before the switch from fast feed to cutting feed, and the gain value is switched in stages by multiplying it by a predetermined time constant. In this way, by changing only the integral gain in stages, it is expected that current steps can be suppressed and vibration can be suppressed.

[0044] Although the embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible in these embodiments without departing from the gist of the invention or the idea and intent of the present disclosure derived from the content described in the claims and their equivalents. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as examples and are not limited to these. The same applies when numerical values ​​or mathematical expressions are used in the description of the above-described embodiments.

[0045] The following are supplementary notes related to embodiments of the present disclosure. (Supplementary Note 1) A control device (1) according to one aspect of the present disclosure includes a servo control unit (150) that controls a motor based on interpolation data that commands a movement amount for each control cycle that controls the motor, and when switching from a cutting feed mode to a fast-forward mode, the servo control unit (150) switches the gain for cutting feed to a gain for fast-forward immediately before the speed of the motor reaches a maximum cutting feed speed, and when switching from the fast-forward mode to the cutting feed mode, switches from the gain for fast-forward to the gain for cutting feed immediately after the speed of the motor falls below the maximum cutting feed speed.

[0046] (Supplementary Note 2) The servo control unit (150) provided in the control device (1) according to another aspect of the present disclosure gradually switches only the integral gain for cutting feed to the integral gain for fast feed by multiplying it by a predetermined time constant T during the period from immediately after switching from the cutting feed mode to the fast feed mode until the speed of the motor reaches the maximum cutting feed speed, and when switching from the fast feed mode to the cutting feed mode, gradually switches only the integral gain for fast feed to the integral gain for cutting feed by multiplying it by a predetermined time constant T during the period from when the speed of the motor falls below the maximum cutting feed speed until the feed mode switches from the fast feed mode to the cutting feed mode.

[0047] REFERENCE SIGNS LIST 1 Control device 3 Industrial machine 4 Control device 5 Network 6 Fog computer 7 Cloud server 11 CPU 12 ROM 13 RAM 14 Non-volatile memory 15, 18, 19, 20 Interface 16 PLC 17 I / O unit 22 Bus 30 Axis control circuit 40 Servo amplifier 50 Servo motor 60 Spindle control circuit 61 Spindle amplifier 62 Spindle motor 63 Position coder 70 Display device 71 Input device 72 External device 100 Program analysis unit 120 Interpolation unit 140 Control unit 150 Servo control unit 151 Position control unit 152 Speed ​​control unit 153 Speed ​​calculation unit 154 Proportional gain unit 155 Integral gain unit 156 Integrator 157 Gain switching filter 200 Control program

Claims

1. A control device comprising a servo control unit that controls a motor based on interpolation data that commands the amount of movement for each control cycle that controls the motor, wherein when switching from cutting feed mode to fast feed mode, the servo control unit switches the gain for cutting feed to the gain for fast feed just before the motor speed reaches the maximum cutting feed speed, and when switching from fast feed mode to cutting feed mode, the servo control unit switches from the gain for fast feed to the gain for cutting feed just after the motor speed falls below the maximum cutting feed speed.

2. The control device according to claim 1, wherein the servo control unit gradually switches only the integral gain for cutting feed to the integral gain for fast feed by multiplying it by a predetermined time constant T during the period from immediately after switching from cutting feed mode to fast feed mode until the speed of the motor reaches the maximum cutting feed speed, and when switching from fast feed mode to cutting feed mode, gradually switches only the integral gain for fast feed to the integral gain for cutting feed by multiplying it by a predetermined time constant T during the period from when the speed of the motor falls below the maximum cutting feed speed until the feed mode switches from fast feed mode to cutting feed mode.

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