Motor Control Device

Abstract

The present invention addresses the problem of, when an abnormality has occurred in one detector, switching to feedback control based on a detector in which an abnormality has not occurred.　This motor control device 100 is provided with a first abnormality detection unit 115 that detects an abnormality in a separate detector 154 as the detector or a feedback cable 1541 thereof, a second abnormality detection unit 116 that detects an abnormality in an encoder 151 of a motor as the detector or a feedback cable 1511 thereof, and a switching unit 111 that switches from full-closed control to semi-closed control, or to control using only the separate detector. When either of the first abnormality detection unit 115 or the second abnormality detection unit 116 has detected an abnormality, the switching unit 111 switches to control using only any detector in which an abnormality has not occurred.

Description

[Technical field]

[0001] The present invention relates to a motor control device. [Background technology]

[0002] In machines such as machine tools, industrial machines, and industrial robots, when controlling the position and speed of a moving part of a machine driven by an electric motor such as a servo motor, a position detector and a speed detector are used to perform position loop control, and a speed loop is provided within the position loop to perform position and speed feedback control. Examples of such position and speed feedback control include semi-closed loop control (hereinafter also referred to as "semi-closed control") and full-closed loop control (hereinafter also referred to as "full-closed control"). In semi-closed control, position and speed are detected by a detector such as a rotary encoder (hereinafter also referred to as "encoder") during feedback control of position and speed. In full-closed loop control, feedback control of position and speed is performed based on the speed of the electric motor that drives the moving parts of the machine, and the position is detected by a position detector such as a scale (hereinafter also referred to as "separate detector"). In addition, feedback control using only a separate detector, in which both the position and the speed are detected by a separate detector (hereinafter also referred to as "control using only a separate detector"), is also given as an example of feedback control.

[0003] Patent Document 1 describes a control system 100 that can be operated by connecting the machine end detector to a controller 1 and switching between a control system that controls the drive mechanism in a semi-closed mode and a control system that controls the drive mechanism in a fully closed mode by a changeover switch 12 in the controller 1 when the interface of the servo amplifier 2 does not support connection with the machine end detector that detects the position of the drive mechanism. Note that the control system 100 described in Patent Document 1 is premised on the fact that the changeover switch 12 is switched in advance to the SC (semi-closed control) side when the drive mechanism is processed by semi-closed control, and the changeover switch 12 is switched in advance to the FC (fully closed control) side when the drive mechanism is fully closed control. Patent Document 1 does not switch to semi-closed control when, for example, an abnormality occurs in the machine end detector or its feedback cable during full closed control, or switch to control only the machine end detector when an abnormality occurs in the motor end detector or its feedback cable during full closed control. In this regard, Patent Document 2 describes a method of controlling an electric motor when a detector has an abnormality, in order to reduce damage to the machine or other objects caused by collision of the moving part of the machine with other objects when an abnormality occurs in the position detector or speed detector. Patent Document 2 merely discloses a technology for stopping the moving part of the machine by switching to speed control and performing deceleration control with a speed command of, for example, "0" when a position detector 10 such as a scale cannot detect a position normally. The invention described in Patent Document 2 does not switch to, for example, semi-closed control when an abnormality occurs in the position detector 10 such as a scale or its feedback cable during full-closed control, or does not switch to control of only the position detector 10 such as a scale when an abnormality occurs in a detector such as an encoder or its feedback cable during full-closed control. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-095492 A [Patent Document 2] Japanese Patent Application Publication No. 10-277887 Summary of the Invention [Problem to be solved by the invention]

[0005] There is a demand for a control device that can switch to feedback control based on a detector that is not experiencing an abnormality, for example by switching to semi-closed control when an abnormality occurs in a separate detector or its feedback cable during full-closed control, or by switching to control of only the separate detector when an abnormality occurs in a detector such as an encoder or its feedback cable during full-closed control.

[0006] An object of the present invention is to provide a control device that, when an abnormality occurs in one detector, can switch to feedback control based on a detector that is not abnormal. [Means for solving the problem]

[0007] (1) A motor control device according to one aspect of the present invention is a motor control device that controls a motor of a machine tool, a robot, or an industrial machine, and includes a motor control unit: The motor control unit includes: a first abnormality detection unit that detects an abnormality in a separately installed detector as a detector or in a feedback cable connected to the separately installed detector; A second abnormality detection unit that detects an abnormality in a rotary encoder of the motor or a feedback cable connected to the rotary encoder as a detector; A switching unit that switches from full-closed control to semi-closed control or to control of only the separately installed detector, When an abnormality is detected in either the first abnormality detection section or the second abnormality detection section, the switching section switches to control using only the one of the detectors that has not detected an abnormality. Effect of the Invention

[0008] According to one aspect of the present invention, it is possible to provide a control device that, when an abnormality occurs in one detector, can switch to feedback control based on a detector that is not abnormal. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing a system configuration of a motor control device according to an embodiment of the present invention; [Diagram 2] 1 is a diagram illustrating an overview of a case in which the motor control device according to the present embodiment performs full-closed control. [Diagram 3] 1 is a diagram illustrating an overview of a case in which the motor control device according to the present embodiment performs semi-closed control. [Figure 4] 1 is a diagram showing an outline of a case in which the motor control device according to the present embodiment performs control using only a separately-mounted detector; [Figure 5A] 5 is a flowchart illustrating the flow of processing that the motor control device according to the present embodiment executes for each position and speed loop processing period. [Figure 5B] 5 is a flowchart illustrating the flow of processing that the motor control device according to the present embodiment executes for each position and speed loop processing period. [Figure 5C] 5 is a flowchart illustrating the flow of processing that the motor control device according to the present embodiment executes for each position and speed loop processing period. [Figure 5D] 5 is a flowchart illustrating the flow of processing that the motor control device according to the present embodiment executes for each position and speed loop processing period. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the system configuration of a motor control device according to this embodiment. First, a motor control device according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a control system 10 according to the first embodiment of the present invention. The control system 10 according to the first embodiment of the present invention includes a control device 400, a motor control device 100, a motor 150, a connecting mechanism 152, and a table 153. Here, the control device 400 is, for example, a higher-level control device such as a numerical control device that controls a machine tool or a robot control device that controls a robot. The motor control device 100 is connected to the control device 400. In this embodiment, it is assumed that the motor control device 100 includes a motor control unit 110, a motor 150, a connecting mechanism 152, and a table 153.

[0011] The motor 150 is included in, for example, a machine tool, a robot, an industrial machine, etc., which are controlled by the motor control unit 110. The motor control unit 110 may be provided together with the motor 150 as a part of the machine tool, the robot, the industrial machine, etc. For example, in a machine tool, when a table on which a workpiece (workpiece) is placed is moved in the X-axis and Y-axis directions, a motor control unit 110 and a motor 150 shown in Fig. 1 are provided for the X-axis and Y-axis directions, respectively. When the table is moved in three or more axial directions, a motor control unit 110 and a motor 150 are provided for each axial direction.

[0012] The motor control unit 110, for example, moves the table 153 via a connecting mechanism 152 using the motor 150, thereby machining a workpiece (work) placed on the table 153. The connecting mechanism 152 has a coupling 1521 connected to the motor 150 and a ball screw 1523 fixed to the coupling 1521, and a nut 1522 is screwed onto the ball screw 1523. The nut 1522 screwed onto the ball screw 1523 moves in the axial direction of the ball screw 1523 due to the rotational drive of the motor 150. The table 153 moves due to the movement of the nut 1522.

[0013] The rotation angle position of the motor 150 is detected by a rotary encoder 151 (hereinafter referred to as "encoder 151") provided on the motor 150, and the detected rotation position (amount of rotation) is used as position feedback (position FB) in semi-closed control. Here, since the rotation angle position of the motor 150 and the position of the table 153 correspond to each other, the rotation position detected by the encoder 151, i.e., the position FB value, indicates the position of the table 153. Note that, when the signal detected by the encoder 151 is used as position feedback (position FB) information, since a connecting mechanism 152 such as a ball screw 1523, a coupling 1521, and a nut 1522 exists between the motor 150 and the table 153, errors occur due to gear backlash in the connecting mechanism 152, pitch error of the ball screw, torsion, elongation, thermal expansion, etc. of the ball screw, and the motor position may not necessarily be the same value as the table 153, and in such a case, the error needs to be corrected. Furthermore, a speed is calculated in a speed calculation unit 104 based on a position FB value detected by the encoder 151, and the calculated speed is used as a speed feedback (speed FB). When the encoder 151 is capable of detecting the rotation speed, the detected speed may be made available as speed feedback (speed FB).

[0014] The motor control device 100 includes a position detector (hereinafter referred to as "separate detector 154") that is attached to the end of the ball screw 1523 and detects the travel distance of the ball screw 1523, in addition to the encoder 151 that detects the rotational angle position of the motor 150. The output of the separate detector 154 indicates the position of the table 153, and is used as position feedback in full-closed control or control using only the separate detector 154. In addition, the velocity can be calculated by performing a differential operation in the velocity calculation unit 104 based on the position of the table 153 detected by the separate detector 154, and the calculated velocity can be used as velocity feedback (velocity FB) in control using only the separate detector. In addition, when the position of table 153 is directly read by separate detector 154 and used as position feedback (position FB) information, unlike when the signal detected by encoder 151 is used as position feedback (position FB) information, there is no need to correct errors due to gear backlash in connecting mechanism 152 between motor 150 and table 153, ball screw pitch error, ball screw twist, elongation, thermal expansion, etc., and highly reliable position feedback (position FB) information can be detected.

[0015] 1, the motor control unit 110 includes a switching unit 111. The motor control unit 110 uses the position feedback switching switch 121 to a contact 121a on the separately placed detector 154 side by the switching unit 111, thereby setting the position information of the table 153 detected by the separately placed detector 154 as position feedback (position FB) information. Also, by connecting the position feedback switching switch 121 to a contact 121b on the encoder 151 side, it is possible to switch so that the position information detected by the encoder 151 is set as position feedback (position FB) information. Specifically, for example, when the motor control unit 110 uses the position information of the table 153 detected by the separately placed detector 154 as the position feedback (position FB) information, if an abnormality is detected in the separately placed detector 154 or its feedback cable 1541, the switching unit 111 can switch so that the position information detected by the encoder 151 is used as the position feedback (position FB) information by connecting the position FB changeover switch 121 to the contact 121b on the encoder 151 side. Details of the switching process will be described later. Moreover, the motor control unit 110 uses the speed FB changeover switch 122 to a contact 122a on the separately placed detector 154 side by using the switching unit 111, thereby setting the speed information calculated based on the position information of the table 153 detected by the separately placed detector 154 as the speed feedback (speed FB) information. Also, by connecting the speed FB changeover switch 122 to a contact 122b on the encoder 151 side, it is possible to switch so that the speed information detected / calculated by the encoder 151 is set as the speed feedback (speed FB) information. Specifically, for example, when the motor control unit 110 uses speed information calculated based on position information detected by the encoder 151 as speed feedback (speed FB) information, if an abnormality is detected in the encoder 151 or its feedback cable 1511, the switching unit 111 can switch so that the speed information calculated based on the position information detected by the separately placed detector 154 is used as the speed feedback (speed FB) information by connecting the speed FB changeover switch 122 to the contact 122a on the separately placed detector 154 side. Details of the switching process will be described later.

[0016] Before describing the configuration for executing the switching process, a brief description will be given of fully closed control, control using only a separate detector, and semi-closed control. As shown in FIG. 1, the motor control unit 110 includes a position subtraction unit 102, a position control unit 103, a speed subtraction unit 105, and a speed control unit .

[0017] First, the full-closed control will be described. Fig. 2 shows an outline of the case where the motor control device 100 according to this embodiment performs the full-closed control. As shown in Fig. 2, the position FB changeover switch 121 is connected to a contact 121a on the separately installed detector 154 side, and the speed FB changeover switch 122 is connected to a contact 122b on the encoder 151 side. The control device 400 sets the feed rate based on the machining program and adjusts the position command value y * and create the position command value y* is input to the motor control unit 110. More specifically, the position command value y * is input to the position subtraction unit 102. The position subtraction unit 102 calculates the position command value y * and the mechanical position as feedback position information fed back by a separately installed detector 154, and the difference is output to the position control unit 103 as a position deviation. The position control unit 103 calculates, for example, a value obtained by multiplying the position deviation by a position gain Kp as a speed command value v * to the speed subtraction unit 105. The speed subtraction unit 105 subtracts the speed command value v * and the motor speed as speed feedback (speed FB) calculated in speed calculation section 104 based on the position FB value detected by encoder 151, and the difference is output to speed control section 106 as a speed deviation. The speed control unit 106 has, for example, a transfer function C V The torque command value T M is output to the motor 150 to drive the motor 150.

[0018] Next, the case of semi-closed control will be described. Fig. 3 shows an outline of the case where the motor control device 100 according to this embodiment performs semi-closed control. As shown in Fig. 3, in this case, the position FB changeover switch 121 is connected to the contact 121b on the encoder 151 side, and the speed FB changeover switch 122 is connected to the contact 122b on the encoder 151 side. Semi-closed control can be explained by replacing "feedback position information fed back by the separately placed detector 154" in the above explanation of fully closed control with "feedback position information fed back by the encoder 151."

[0019] Finally, the case of control using only the separately installed detector will be described. Fig. 4 shows an overview of the case where the motor control device 100 according to this embodiment performs control using only the separately installed detector. As shown in Fig. 4, the position FB changeover switch 121 is connected to a contact 121a on the separately installed detector 154 side, and the speed FB changeover switch 122 is connected to a contact 122a on the separately installed detector 154 side. Control using only the separate detector can be explained by replacing "speed feedback information calculated in the speed calculation unit 104 based on the position FB value detected by the encoder 151" in the above description of the fully closed control with "speed feedback information speed-feedback by the separate detector 154."

[0020] Next, a configuration and process for switching to feedback control based on a detector that is not malfunctioning when an abnormality occurs in either the separately mounted detector 154 or the encoder 151 will be described. 1, the motor control unit 110 includes, in addition to the above-mentioned switching unit 111, a first abnormality detection unit 115, a second abnormality detection unit 116, a position information recording unit 117, and a correction value calculation unit 118. The motor control unit 110 also includes a storage unit 120.

[0021] The first abnormality detection unit 115 detects an abnormality in the separately placed detector 154 or its feedback cable 1541. Specifically, the first abnormality detection unit 115 determines and detects an abnormality in the separately placed detector 154 or its feedback cable 1541 from a discontinuance of a signal or position information, such as whether an abnormal signal is being output from the separately placed detector 154 due to an inability to detect the position or the like, or whether an abnormal signal such as a disconnection alarm is being output due to a malfunction of the separately placed detector 154.

[0022] The second abnormality detection unit 116 detects an abnormality in the encoder 151 or its feedback cable 1511. Specifically, the second abnormality detection unit 116 determines and detects an abnormality in the encoder 151 or its feedback cable 1511 from a discontinuance of a signal or position information, such as whether an abnormal signal is being output from the encoder 151 due to an inability to detect position or the like, or whether an abnormal signal such as a disconnection alarm is being output due to a malfunction of the encoder 151.

[0023] The position information recording unit 117 updates and records the position information during semi-closed control even during full-closed control. Specifically, when full-closed control is being performed, the position information of the table 153 detected by the separate detector 154 (hereinafter also referred to as "full-closed control position FB information") is used as position feedback (position FB) information, and simultaneously, the position information detected by the encoder 151 (hereinafter also referred to as "semi-closed control position FB information") is acquired, and the information is updated and stored in the storage unit 120 together with the full-closed control position FB information so that it is always the latest information. In addition, the position information recording unit 117 acquires position information (semi-closed control position FB information) detected by the encoder 151 when full-closed control is being performed, using the position information (fully-closed control position FB information) of the table 153 detected by the separate detector 154 as position feedback (position FB) information, and may update and store, for example, a value obtained by subtracting the semi-closed control position FB information from the fully-closed control position FB information (hereinafter also referred to as the "position FB information difference") in the memory unit 120 so that it is always the latest information.

[0024] As described above, during full-close control, the position FB changeover switch 121 is connected to the contact 121a on the separately-mounted detector 154 side, and the speed FB changeover switch 122 is connected to the contact 122b on the encoder 151 side. When the first abnormality detection unit 115 detects an abnormality in the separately placed detector 154 or its feedback cable 1541 during full-close control, the switching unit 111 connects the position FB changeover switch 121 to the contact 121b on the encoder 151 side, thereby switching so that the position information detected by the encoder 151 is input as position feedback (position FB) information to the position subtraction unit 102 in place of the position information of the table 153 detected by the separately placed detector 154. This allows for a swift transition from full-closed control to semi-closed control. As described above, when the signal detected by the encoder 151 is used as the position feedback (position FB) information, unlike when the position of the table 153 is directly read by the separate detector 154 and used as the position feedback (position FB) information, there are errors due to gear backlash in the connecting mechanism 152, ball screw pitch error, ball screw torsion, elongation, thermal expansion, etc., that exist between the motor 150 and the table 153. For this reason, when the position feedback information is changed from the position information of the table 153 detected by the separate detector 154 to the position information detected by the encoder 151, the errors may cause a shock during feedback control. Therefore, when the first abnormality detection unit 115 detects an abnormality in the separately placed detector 154 or its feedback cable 1541, the correction value calculation unit 118 outputs a value obtained by correcting the position information detected by the encoder 151 immediately after switching based on the position FB information difference immediately before switching stored in the storage unit 120 to the switching unit 111. The switching unit 111 inputs the correction value corrected by the correction value calculation unit 118 to the position subtraction unit 102 as position feedback (position FB) information. In this way, it is possible to reduce a shock at the time of switching in which the position information detected by the encoder 151 is input to the position subtraction unit 102 as position feedback (position FB) information instead of the position information of the table 153 detected by the separately placed detector 154.

[0025] Furthermore, when the second abnormality detection unit 116 detects an abnormality in the encoder 151 or its feedback cable 1511 during full-close control, the switching unit 111 connects the speed FB changeover switch 122 to the contact 122a on the separately placed detector 154 side, thereby switching so that the speed information calculated based on the position information of the table 153 detected by the separately placed detector 154 is input as speed feedback (speed FB) information to the speed subtraction unit 105. Note that there is no need to correct the speed information accompanying the transition.

[0026] Furthermore, the motor control device 100 is equipped with configurations for both full-closed control and semi-closed control, and can perform either type of control. For this reason, feedback control may be performed using semi-closed control rather than full-closed control from the beginning. In this case, when the second abnormality detection unit 116 detects an abnormality in the encoder 151 or its feedback cable 1511, the switching unit 111 connects the position FB changeover switch 121 to a contact 121a on the separately installed detector 154 side and connects the speed FB changeover switch 122 to a contact 122a on the separately installed detector 154 side, thereby switching to control using only the separately installed detector. The correction value calculation unit 118 may output to the switching unit 111 a value obtained by correcting the position information of the table 153 detected by the separately placed detector 154 immediately after switching to the position information detected by the encoder 151 based on the position FB information difference immediately before switching stored in the storage unit 120. This allows the switching unit 111 to input the correction value corrected by the correction value calculation unit 118 to the position subtraction unit 102 as position feedback (position FB) information. This makes it possible to reduce the shock at the time of switching when the position information of the table 153 detected by the separately placed detector 154 is input to the position subtraction unit 102 as position feedback (position FB) information instead of the position information detected by the encoder 151. In this way, when an abnormality occurs in one detector, motor control unit 110 can switch to feedback control based on a detector that is not experiencing an abnormality.

[0027] Next, a process to be performed after switching to feedback control based on a detector that is not malfunctioning when an abnormality occurs in one detector will be described. As described above, when an abnormality occurs in one detector, the control device 400 can continue to execute the machining program that is currently being executed by switching to feedback control based on a detector that is not abnormal, even after the switch. Furthermore, the motor control unit 110 can also stop the ongoing machining process after switching. Specifically, for example, the motor control unit 110 (switching unit 111) may stop the machining process by inputting a position command to the position subtraction unit 102 to perform speed control using a deceleration speed control command of a predetermined pattern set in advance, instead of the position command from the control device 400, to stop the machine movable part (table 153, etc.). Furthermore, when stopping the motor after switching, the motor control unit 110 (switching unit 111) may switch from position control to speed control, and control the speed by inputting a speed command to the speed subtraction unit 105 for decelerating the speed at the time of switching in a predetermined pattern to 0. In this case, the speed feedback may use speed feedback information detected by a detector in which no abnormality is occurring, such as a pulse coder. The selection of whether to stop or continue machining may be made based on a parameter value set in advance.

[0028] Next, the operation of the motor control device 100 (motor control unit 110) will be described. Figures 5A to 5D are flowcharts explaining the flow of processing that the motor control device 100 (motor control unit 110) executes for each position and speed loop processing cycle. Here, a processing flow is explained for a case where, when an abnormality occurs in one detector during full-closed control, the motor control device 100 switches to feedback control based on a detector that is not experiencing an abnormality, thereby allowing the control device 400 to continue executing the machining program being executed after the switch.

[0029] 5A, in step S1, the first abnormality detection unit 115 detects the presence or absence of an abnormality in the separately installed detector 154 or its feedback cable 1541. If no abnormality is detected, the process proceeds to step S2. If an abnormality is detected, the process proceeds to step S11.

[0030] In step S2, the second abnormality detection unit 116 detects the presence or absence of an abnormality in the encoder 151 or its feedback cable 1511. If no abnormality is detected, the process proceeds to step S3. If an abnormality is detected, the process proceeds to step S21.

[0031] In step S3, the motor control unit 110 performs position control and speed control based on the fully closed control in the current processing cycle. In step S4, the position information recording unit 117 acquires the semi-closed control position FB information together with the fully-closed control position FB information in the processing cycle, and updates and stores the semi-closed control position FB information together with the fully-closed control position FB information in the storage unit 120 so that the information is always the latest. After that, the process proceeds to step S1 to perform position and speed loop processing in the next cycle. The order of steps S3 and S4 may be reversed. In this way, unless any abnormality is detected in the separately mounted detector 154 or its feedback cable 1541 and the encoder 151 or its feedback cable 1511, full closed control is performed, and the motor 150 is driven and the table 153 is moved every processing cycle.

[0032] 5B, in step S11, the second abnormality detection unit 116 detects the presence or absence of an abnormality in the encoder 151 or its feedback cable 1511. If no abnormality is detected, the process proceeds to step S12. If an abnormality is detected, the process proceeds to step S31.

[0033] In step S12, in order to switch from fully closed control to semi-closed control, the correction value calculation unit 118 calculates the difference between the fully closed control position FB information and the semi-closed control position FB information immediately before the switching stored in the memory unit 120 as a correction value at the time of switching.

[0034] In step S13, the switching unit 111 switches from full-closed control to semi-closed control by connecting the position FB switching switch 121 to the contact 121b on the encoder 151 side. At that time, position feedback (position FB) information obtained by correcting the position information detected by the encoder 151 based on the correction value calculated in step S12 is input to the position subtraction unit 102 in place of the position information of the table 153 detected by the separately installed detector 154.

[0035] In step S14, the motor control unit 110 performs position control and speed control by semi-closed control in the current processing cycle, and then proceeds to S15.

[0036] In step S15, the second abnormality detection unit 116 detects the presence or absence of an abnormality in the encoder 151 or its feedback cable 1511. If no abnormality is detected, the process proceeds to step S14. If an abnormality is detected, the process proceeds to step S31. In this way, by switching to feedback control based on the encoder 151 in which no abnormality is occurring, the control device 400 can continue to execute the machining program that is currently being executed even after the switch.

[0037] Next, referring to FIG. 5C, in step S21, in order to switch from fully closed control to control using only the separately placed detector, the switching unit 111 connects the speed FB switching switch 122 to the contact 122a on the separately placed detector 154 side, and inputs speed information calculated based on position information of the table 153 detected by the separately placed detector 154 to the speed subtraction unit 105 as speed feedback (speed FB) information.

[0038] In step S22, the motor control unit 110 performs position control and speed control using only the separately-installed detector in the current processing cycle, and then proceeds to S23.

[0039] In step S23, the first abnormality detection unit 115 detects the presence or absence of an abnormality in the separately installed detector 154 or its feedback cable 1541. If no abnormality is detected, the process proceeds to step S22. If an abnormality is detected, the process proceeds to step S31. In this way, by switching to speed feedback control based on the separately mounted detector 154 in which no abnormality is occurring, the control device 400 can continue to execute the machining program that is being executed even after the switching.

[0040] Finally, referring to FIG. 5D, in step S31, since an abnormality is detected in the separately mounted detector 154 or its feedback cable 1541 and the encoder 151 or its feedback cable 1511, it is determined that the position and speed control loops are not operating normally, and the motor control unit 110, for example, cuts off the power to the motor, connects a resistor between the phases of the motor to activate the dynamic brake, and brings the motor 150 and the machine to an emergency stop. The above process flow is a process flow in which the control device 400 continues to execute the machining program being executed even after switching, but as described above, the process may be stopped after switching.

[0041] As described above, the motor control device 100 has both the configuration of full-closed control and semi-closed control, and can control either. Therefore, it may be configured to operate by applying feedback control by semi-closed control instead of full-closed control from the beginning. Even in this case, when an abnormality occurs in the encoder 151 or its feedback cable 1511, it is possible to switch to control by only the separately installed detector, so that the machining program being executed by the control device 400 can be continued even after the switch. The operation process flow in this case will be briefly described.

[0042] Semi-closed control is executed first, and at each processing cycle of the semi-closed control, the second abnormality detection unit 116 detects whether or not there is an abnormality in the encoder 151 or its feedback cable 1511, and if no abnormality is detected, the second abnormality detection unit 116 executes semi-closed control, and if an abnormality is detected, the second abnormality detection unit 116 switches to control using only the separately installed detector.

[0043] After switching to control using only the separate detector, the first abnormality detection unit 115 detects for the presence or absence of an abnormality in the separate detector 154 or its feedback cable 1541 for each processing cycle, and if no abnormality is detected, control is performed using only the separate detector, and if an abnormality is detected, the motor control unit 110, for example, cuts off power to the motor and connects a resistor between the phases of the motor to activate the dynamic brake, thereby bringing the motor 150 and the machine to an emergency stop. The process flow for switching to feedback control based on a detector that is not experiencing an abnormality in motor control device 100 of this embodiment when an abnormality occurs in one of the detectors has been described above.

[0044] The motor control unit 110 of the motor control device 100 described above is composed of a processor such as a CPU, memories such as ROM and RAM, input / output circuits, etc., and each component included in the motor control unit 110 can be realized by this hardware, various software stored in the memory, or a combination of these. Here, being realized by software means being realized by loading various programs and executing them with a processor such as a CPU.

[0045] The program can be stored and provided to the computer using various types of non-transitory computer readable media. The non-transitory computer readable media includes various types of tangible storage media. Examples of the non-transitory computer readable media include magnetic recording media (e.g., flexible disks, hard disk drives), magneto-optical recording media (e.g., magneto-optical disks), CD-ROM (Read Only Memory), CD-R, CD-R / W, and semiconductor memory (e.g., mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (random access memory)). The program may also be provided to the computer by various types of transitory computer readable media.

[0046] The above-described embodiment is a preferred embodiment of the present invention, but the scope of the present invention is not limited to the above-described embodiment, and the present invention can be implemented in various modified forms without departing from the gist of the present invention.

[0047] <Variation 1> In the above embodiment, the motor control device 100 is a device separate from the control device 400, but this is not limited to the above. For example, the motor control device 100 may be included in the control device 400.

[0048] <Variation 2> In the above embodiment, the switching unit 111, the first abnormality detection unit 115, the second abnormality detection unit 116, the position information recording unit 117, and the correction value calculation unit 118 are included in the motor control unit 110, but this is not limited to the above. For example, if the motor control unit 110 only drives the motor 150, the switching unit 111, the first abnormality detection unit 115, the second abnormality detection unit 116, the position information recording unit 117, and the correction value calculation unit 118 may be included in the control device 400.

[0049] <Variation 3> In the above embodiment, when speed feedback (speed FB) information is detected by the encoder 151, the speed calculation unit 104 calculates the speed from the position information based on the rotational position (amount of rotation) detected by the encoder 151, and the calculated speed is used as the speed feedback (speed FB), but this is not limiting. The rotational speed of the motor 150 may be detected, and the detected speed may be used as the speed feedback (speed FB).

[0050] Considering the above, the motor control device of the present disclosure can take various forms having the following configurations.

[0051] (1) The motor control device 100 of the present disclosure includes a motor control unit 110, a first abnormality detection unit 115 that detects abnormalities in a separate detector 154 as a detector or a feedback cable 1541 connected to the separate detector 154, a second abnormality detection unit 116 that detects abnormalities in a rotary encoder 151 of the motor or a feedback cable 1511 connected to the rotary encoder 151 as a detector, and a switching unit 111 that switches from fully closed control to semi-closed control or control using only the separate detector, and when an abnormality is detected in either the first abnormality detection unit 115 or the second abnormality detection unit 116, the switching unit 111 switches to control using only whichever detector has not detected the abnormality. According to this motor control device 100, when an abnormality occurs in one detector, it is possible to switch to feedback control based on a detector that is not experiencing an abnormality.

[0052] (2) In the motor control device 100 described in (1), the first abnormality detection unit 115 or the second abnormality detection unit 116 may detect and determine an abnormality from a disruption of a signal or position information. In this way, motor controller 100 can detect an abnormality in the detector or its feedback cable.

[0053] (3) In the motor control device 100 described in (1) or (2), the motor control unit 110 further has a correction value calculation unit 118 that calculates a position error based on position information detected by the rotary encoder 151 and position information detected by the separate detector 154, and the switching unit 111 may be configured to correct the position information detected by the rotary encoder 151 based on the correction value calculated by the correction value calculation unit 118 when switching from fully closed control to semi-closed control. By doing so, the motor control device 100 can correct the difference in position between the full-closed control and the semi-closed control due to backlash or torsion, and can reduce or eliminate shock at the time of switching.

[0054] (4) The motor control device 100 described in (3) includes a memory unit 120, and the motor control unit 110 further includes a position information recording unit 117 that stores at least the position information most recently detected by the rotary encoder 151 and the position information most recently detected by the separate detector 154 in the memory unit 120, and the correction value calculation unit 118 may calculate a position error based on the position information stored in the memory unit 120. By doing so, the motor control device 100 can calculate the position error more accurately.

[0055] (5) The motor control device 100 described in (3) may be provided with a memory unit 120, and the correction value calculation unit 118 may store in the memory unit 120 a correction value calculated based on the position information most recently detected by the rotary encoder 151 and the position information most recently detected by the separate detector 154. In this way, the motor control device 100 can achieve the same effect as (4). [Explanation of symbols]

[0056] 10. Control System 400 Control device 100 Motor control device 110 Motor control unit 102 Position subtraction unit 103 Position control section 104 Speed ​​calculation section 105 Speed ​​subtraction section 106 Speed ​​control section 111 Switching section 115 First abnormality detection unit 116 Second abnormality detection unit 117 Location information recording unit 118 Correction value calculation unit 120 Storage section 121 Position FB changeover switch 121a Contact 121b Contact 122 Speed ​​feedback switch 122a Contact 122b Contact 150 Motor 151 Rotary Encoder (Encoder) 1511 Feedback Cable 152 Connection mechanism 1521 Coupling 1522 Nut 1523 Ball screw 153 Table 154 Separate detector 1541 Feedback Cable

Claims

1. In a motor control device that controls a motor of a machine tool, a robot, or an industrial machine, A control unit is provided, The control unit is a first abnormality detection unit that detects an abnormality in a separately-installed detector as a detector or in a feedback cable connected to the separately-installed detector; a second abnormality detection unit that detects an abnormality in a rotary encoder of the motor or a feedback cable connected to the rotary encoder; A switching unit that switches from full-closed control to semi-closed control or to control of only the separately installed detector, The motor control device is characterized in that, when an abnormality is detected in either the first abnormality detection unit or the second abnormality detection unit, the switching unit switches to control in which the currently running machining program continues to be executed using only one of the detectors that has not detected an abnormality.

2. 2. The motor control device according to claim 1, wherein the first abnormality detection unit or the second abnormality detection unit detects and determines an abnormality from a disruption of a signal or position information.

3. The control unit further a correction value calculation unit that calculates a difference between position information detected by the rotary encoder immediately before switching and position information detected by the separately installed detector as a correction value at the time of switching; 3. The motor control device according to claim 1, wherein the switching unit corrects the position information detected by the rotary encoder based on the correction value calculated by the correction value calculation unit when switching from fully closed control to semi-closed control.

4. A memory unit is provided, The control unit further a position information recording unit that stores in the storage unit at least the position information most recently detected by the rotary encoder and the position information most recently detected by the separately installed detector; 4. The motor control device according to claim 3, wherein the correction value calculation unit calculates the correction value based on the position information stored in the storage unit.

5. A memory unit is provided, 4. The motor control device according to claim 3, wherein the correction value calculation unit stores in the memory unit a correction value calculated based on the position information most recently detected by the rotary encoder and the position information most recently detected by the separately installed detector.

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