Servo motor control device

Abstract

The present invention provides a control device for a servo motor, comprising: a speed comparison unit, which compares the speed at a specific position stop instruction with a first speed; a specific position stop action determination unit, which determines an action method at the specific position stop instruction; and a specific position stop control unit, which controls the servo motor based on the determined action method, wherein, when the speed at the specific position stop instruction is higher than the first speed, the specific position stop action determination unit generates a movement instruction that decelerates to a second speed lower than the first speed and stops at a target position based on an acceleration during deceleration or a predetermined acceleration, and when the speed at the specific position stop instruction is lower than the first speed, the specific position stop action determination unit generates a movement instruction that decelerates at a predetermined deceleration and stops at a target stop position, and the specific position stop control unit controls the servo motor based on the movement instruction.

Description

Technical Field

[0001] The invention relates to a control device for a servo motor. Background Art

[0002] For example, the rotation amount, speed, torque, etc. of the servo motor of industrial machinery such as the servo motor for driving the main shaft of a machine tool are driven and controlled. In addition, the control device of the servo motor detects the position and magnetic pole position (phase (angle) of the motor magnet) of the servo motor using a detector, determines the voltage command value based on various feedback values ​​from the detector, and applies a voltage modulated by pulse width modulation (PWM), thereby controlling the drive of the servo motor.

[0003] In addition, as a method for controlling an action for stopping an industrial machine at a specific position, a so-called positioning (specific position stop) action, for example, the following method has been put into practical use: receiving a positioning instruction, and allowing a maximum current to flow through a servo motor to perform a maximum deceleration control action, detecting the maximum deceleration acceleration, and obtaining a state value that allows the machine to stop at a specific position at the fastest speed. Then, based on the state value, an instruction for stopping at a specific position is generated, and the drive control of the servo motor is performed according to the instruction.

[0004] For example, Patent Document 1 discloses the following: "A specific position stop control device for a rotating axis, characterized in that it comprises: a speed loop control unit, which performs speed control on the rotating axis according to a first speed command having a specified first speed and a second speed command having a specified second speed generated by an upper control device, the second speed being less than the first speed of the first speed command; a movement command generation unit, which generates a movement command according to a control cycle; a position loop control unit, which performs position control on the rotating axis according to a control cycle according to the movement command generated by the movement command generation unit; a switching unit, which switches between speed control of the rotating axis by the speed loop control unit based on the first speed command generated by the upper control device, speed control of the rotating axis by the speed loop control unit based on the second speed command, and position control of the rotating axis by the position loop control unit; and an acceleration detection unit, which detects acceleration. The acceleration of the rotating axis during acceleration and deceleration, wherein, when the rotating axis stops, the switching unit switches the speed control of the rotating axis by the speed loop control unit from the speed control of the rotating axis based on the first speed command generated by the superior control device to the speed control of the rotating axis based on the second speed command, and when the speed of the rotating axis reaches the second speed, the switching unit switches from the speed control of the rotating axis by the speed loop control unit based on the second speed command to the position control of the rotating axis by the position loop control unit, and the movement command generated by the movement command generation unit within a prescribed time after the speed control of the rotating axis by the speed loop control unit based on the second speed command is switched to the position control of the rotating axis by the position loop control unit by the switching unit has the acceleration detected by the acceleration detection unit within a prescribed time before the switching from the speed control to the position control by the switching unit.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 4099503 Summary of the invention

[0008] Problem that the invention aims to solve

[0009] Here, in the above-mentioned positioning control method, the maximum current is made to flow through the servo motor to perform the maximum deceleration control action. In order to detect the maximum deceleration acceleration, when the movement speed of the industrial machinery is high when the positioning command is issued, the time required for the execution of the maximum deceleration control action and the detection of the maximum deceleration acceleration can be ensured, and the machine can be stopped quickly and effectively at a specific position (a command to stop at a specific position can be generated).

[0010] In contrast, if the movement speed of industrial machinery is somewhat low when a positioning command is issued, it will take time (effort) to execute the maximum deceleration control action and detect the maximum deceleration acceleration, which will in turn increase the time required to stop at a specific position, which may lead to a decrease in work efficiency.

[0011] Therefore, a method of making the industrial machine stop quickly and efficiently at a specific position even when the operating speed of the industrial machine is relatively low when a positioning command is issued is strongly desired.

[0012] Solutions for solving problems

[0013] One mode of the servo motor control device disclosed in the present invention is a servo motor control device for controlling a servo motor that drives a rotating shaft and controlling a specific position stop action, comprising: a speed detection unit that detects the speed of the rotating shaft; a speed setting storage unit that sets and stores a first speed and a second speed that is lower than the first speed; a speed comparison unit that compares the speed at a specific position stop instruction with the first speed; a specific position stop action determination unit that determines an action method at the specific position stop instruction based on a comparison result obtained by the speed comparison unit; and a specific position stop control unit that controls the servo motor based on the action method determined by the specific position stop action determination unit, wherein the specific position stop action determination unit comprises a speed instruction generation unit and a movement instruction generation unit, and If the speed at the time of the specific position stop instruction is higher than the first speed, the speed instruction generating unit and the movement instruction generating unit generate a speed instruction for decelerating to the second speed with maximum torque, and a movement instruction for stopping at a target position based on an acceleration during deceleration calculated according to the speed detected by the speed detecting unit or a predetermined acceleration. If the comparison result is that the speed at the time of the specific position stop instruction is lower than the first speed, the speed instruction generating unit and the movement instruction generating unit generate a speed instruction for decelerating at a predetermined deceleration, and a movement instruction for stopping at a target stop position based on the speed instruction. The specific position stop control unit controls the servo motor based on the speed instruction and the movement instruction generated by the speed instruction generating unit and the movement instruction generating unit.

[0014] Effects of the Invention

[0015] According to one aspect of the servo motor control device disclosed herein, even when the operating speed of an industrial machine or the like is somewhat low when a positioning command is issued, the machine can be stopped quickly and efficiently at a specific position. That is, the positioning operation can be accelerated. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a block diagram showing a servo motor control device according to <Example 1> of one embodiment.

[0017] Figure 2 This is a diagram showing a specific position stop operation control of a servo motor when a servo motor control device of one embodiment is used.

[0018] Figure 3This is a flowchart showing the specific position stop operation control of the servo motor when the servo motor control device of <Example 1> of one form is used.

[0019] Figure 4 This is a block diagram showing a servo motor control device according to <Example 2> which is one mode.

[0020] Figure 5 This is a flowchart showing the specific position stop operation control of the servo motor when the servo motor control device of <Example 2> of one form is used.

[0021] Description of Reference Numerals

[0022] 1: servo motor control device; 2: servo motor; 3: speed detection unit; 4: speed setting storage unit; 5: speed comparison unit; 6: specific position stop action determination unit; 7: specific position stop control unit; 8: acceleration calculation / setting unit; 9: speed command generation unit; 10: movement command generation unit; 11: current detection unit; 12: magnetic flux calculation unit. DETAILED DESCRIPTION

[0023] Below, refer to Figures 1 to 5 A servo motor control device according to an embodiment will be described.

[0024] The present embodiment relates to a servo motor control device for controlling a servo motor that drives a spindle of a machine tool (a rotating axis of industrial machinery), and for controlling a positioning (specific position stop) action that stops the spindle at a specific position where tool replacement can be performed, such as when a tool is replaced.

[0025] In addition, the servo motor control device disclosed in the present invention can be used as long as it can control the positioning action of industrial machinery equipped with a servo motor (rotating axis). Of course, it is not limited to machine tools, and can also be applied to the drive control of servo motors of other industrial machinery such as robots, conveyors, measuring instruments, testing equipment, presses, presses, printing machines, die-casting machines, injection molding machines, food machinery, packaging machines, welding machines, cleaning machines, coating machines, assembly equipment, installation machines, woodworking machinery, sealing devices, cutting machines, etc.

[0026] First, if Figure 1As shown, the control system of the machine tool of this embodiment includes a servo motor control device 1, which is used to control the servo motor 2 that drives the main shaft (rotating axis) of the machine tool based on the instructions of CNC (Computerized Numerical Control) as the instruction unit, and control the positioning (stopping at a specific position) action.

[0027] <Example 1>

[0028] like Figure 1 , Figure 2 As shown, the servo motor control device 1 in <Example 1> of the present embodiment is configured to include: a speed detection unit 3, which detects the speed of the main shaft driven by the servo motor 2; a speed setting storage unit 4, which sets and stores a first speed and a second speed (target speed: parameter) V2 lower than the first speed (parameter) V1; a speed comparison unit 5, which compares the speed at the time of positioning instruction (at the time of specific position stop instruction) with the first speed V1; a specific position stop action determination unit 6, which determines the action method of the servo motor 2 at the time of positioning instruction based on the comparison result obtained by the speed comparison unit 5; and a specific position stop control unit 7, which controls the servo motor 3 based on the action method determined by the specific position stop action determination unit 6. In addition, as Figure 1 As shown, in the present embodiment, the specific position stop operation determination unit 6 is configured to include the speed comparison unit 5 .

[0029] like Figure 1 , Figure 2 As shown, the specific position stop action determination unit 6 includes: an acceleration calculation / setting unit 8, which calculates the acceleration based on the speed detected by the speed detection unit 3, or pre-sets and stores a specified acceleration; a speed instruction generation unit 9, which generates a speed instruction; and a movement instruction generation unit 10, which generates a movement instruction.

[0030] When the comparison result obtained by the speed comparison unit 5 is that the speed at the time of the positioning stop instruction is higher than the first speed V1, the speed instruction generation unit 9 and the movement instruction generation unit 10 generate a speed instruction for decelerating to the second speed V2 with the maximum torque, and a movement instruction for stopping at the target position based on the acceleration during deceleration calculated by the acceleration calculation / setting unit 8 or a predetermined acceleration set in advance.

[0031] In addition, when the comparison result obtained by the speed comparison unit 5 is that the speed at the time of the positioning stop command is lower than the first speed V1, the speed command generation unit 9 and the movement command generation unit 10 generate a speed command for decelerating at a specified deceleration rate and a movement command for stopping at the target stop position based on the speed command.

[0032] In the servo motor control device 1 of the present embodiment, the specific position stop control unit 7 controls the servo motor 2 based on the speed command and the movement command generated by the speed command generation unit 9 and the movement command generation unit 10 .

[0033] More specifically, when the positioning operation is controlled by the servo motor control device 1 of the <Example 1> of the present embodiment, as shown in FIG. Figure 3 ( Figure 1 , Figure 2 ), when a positioning instruction (specific position stop instruction) is issued from the CNC, the speed comparison unit 5 confirms whether the rotation speed of the spindle detected by the speed detection unit 3 during the positioning instruction is greater than the first speed V1 set and stored in the speed setting storage unit 4 (step 1).

[0034] When the comparison result obtained by the speed comparison unit 5 is less than the first speed V1, a movement command generated by the movement command generation unit 10 is issued, and the specific position stop control unit 7 controls the action of the servo motor 2 based on the specified acceleration A pre-set and stored in the acceleration calculation / setting unit 8, that is, the rotation speed of the main shaft is decelerated so that it stops at a specific position (step 2).

[0035] On the other hand, when the comparison result obtained by the speed comparison unit 5 is greater than the first speed V1, the speed instruction generation unit 9 generates a speed instruction with the second speed (target speed) V2 set and stored in the speed setting storage unit 4 as the target, and the movement instruction generation unit 10 generates a movement instruction to stop at the target position based on the acceleration during deceleration calculated by the acceleration calculation / setting unit 8 or a predetermined acceleration set in advance.

[0036] At this time, in order to decelerate to the second speed V2 in a short time after the positioning command is issued, the speed command is generated so as to decelerate to the second speed V2 with the inherent maximum torque of the servo motor 2 .

[0037] In addition, the inherent maximum torque of the servo motor 2 varies depending on the inertia. Therefore, the speed command is generated so as to decelerate to the second speed V2 with an appropriate maximum torque according to the state at the time of the positioning command.

[0038] The movement command (movement command based on the speed command) generated in this way is sent to the specific position stop control unit 7, thereby controlling the drive of the servo motor 2 (step 3). In addition, the acceleration calculation / setting unit 8 calculates the acceleration during deceleration based on the movement command (step 4), and confirms whether the speed detected by the speed detection unit 3 has reached the second speed V2 (step 5).

[0039] When the speed detected by the speed detector 3 has not reached the second speed V2, the servo motor 2 is continuously decelerated and driven based on the movement command, and the acceleration during deceleration is calculated to check whether it has reached the second speed V2 (steps 3, 4, and 5).

[0040] When the speed detected by the speed detection unit 3 reaches the second speed V2, the deceleration control based on the movement instruction is released, and a movement instruction is generated to stop at a specific position based on the acceleration Ad detected at this time, and the drive of the servo motor 2 is controlled based on the movement instruction so that it stops at the specific position (step 6).

[0041] <Example 2>

[0042] Here, when the servo motor 2 is an induction motor, Figure 4 As shown, the control device 1 of the servo motor of <Example 2> of the present embodiment is constructed to include, in addition to a speed detection unit 3, a speed setting storage unit 4, a speed comparison unit 5 (specific position stop action determination unit 6), a specific position stop control unit 7, an acceleration calculation / setting unit 8 (specific position stop action determination unit 6), a speed command generation unit 9 (specific position stop action determination unit 6) and a movement command generation unit 10 (specific position stop action determination unit 6), a current detection unit 11 for detecting the current value of the servo motor 2, and a magnetic flux calculation unit 12 for calculating the magnetic flux based on the current value detected by the current detection unit 11.

[0043] In addition, in this case, when the speed at the time of the positioning instruction is lower than the first speed V1 and deceleration is performed at a specified deceleration rate, the speed instruction generating unit 9 and the movement instruction generating unit 10 generate a speed instruction for decelerating at a specified deceleration rate that is corrected based on the magnetic flux at the start of deceleration to a predetermined deceleration rate, and a movement instruction for stopping at the target stop position based on the speed instruction.

[0044] Furthermore, when the positioning operation is controlled by the servo motor control device 1 of the <Example 2> of this embodiment, as shown in FIG. Figure 5 ( Figure 2 , Figure 4 ), first, as in the case of <Example 1>, when a positioning command (specific position stop command) is issued from the CNC, the speed comparison unit 5 confirms whether the rotation speed of the spindle detected by the speed detection unit 3 at the time of the positioning command is greater than the first speed V1 set and stored in the speed setting storage unit 4 (step 1).

[0045] When the comparison result obtained by the speed comparison unit 5 is greater than the first speed V1, the speed instruction generation unit 9 generates a speed instruction with the second speed (target speed) V2 as the target, and the movement instruction generation unit 10 generates a movement instruction to stop at the target position based on the acceleration during deceleration or a pre-set specified acceleration.

[0046] The generated movement command (movement command based on the speed command) is sent to the specific position stop control unit 7, thereby controlling the drive of the servo motor 2 (step 3). The acceleration during deceleration based on the movement command is calculated (step 4), and it is confirmed whether the speed detected by the speed detection unit 3 has reached the second speed V2 (step 5).

[0047] When the speed detected by the speed detector 3 has not reached the second speed V2, the servo motor 2 is continuously decelerated and driven based on the movement command, and the acceleration during deceleration is calculated to check whether it has reached the second speed V2 (steps 3, 4, and 5).

[0048] When the speed detected by the speed detector 3 reaches the second speed V2, a movement command is generated to stop at a specific position based on the acceleration Ad detected at this time, and the driving of the servo motor 2 is controlled based on the movement command to stop at the specific position (step 6).

[0049] On the other hand, when the comparison result obtained by the speed comparison unit 5 is less than the first speed V1, it is confirmed whether the servo motor 2 is an induction motor (step 7). If it is not an induction motor, a movement command generated by the movement command generation unit 10 is issued, and the specific position stop control unit 7 controls the action of the servo motor 2 based on the specified acceleration A pre-set and stored in the acceleration calculation / setting unit 8, that is, the rotation speed of the main shaft is decelerated to stop at a specific position (step 2).

[0050] In the case of an induction motor, when the speed at the time of the positioning command is lower than the first speed V1 and deceleration is performed at a prescribed deceleration, the speed command generating unit 9 and the movement command generating unit 10 generate a speed command for decelerating at a prescribed deceleration (a deceleration calculated by a prescribed acceleration A') that is corrected based on the magnetic flux at the start of deceleration to a pre-set and stored deceleration (prescribed acceleration), and a movement command for stopping at a target stop position based on the speed command.

[0051] Then, based on the movement command, the driving of the servo motor 2 is controlled so as to stop at a specific position (step 8).

[0052] Therefore, the servo motor control device 1 of the present embodiment can make the industrial machine or the like stop quickly and efficiently at a specific position even when the operating speed of the industrial machine or the like is somewhat low when the positioning command is issued. That is, the positioning operation can be accelerated.

[0053] An embodiment of the servo motor control device has been described above, but the present invention is not limited to the above-described embodiment and can be modified as appropriate within a scope not departing from the gist of the present invention.

Claims

1. A servo motor control device for controlling a servo motor driving a rotating shaft and controlling a stop action at a specific position, the servo motor control device comprising: a speed detection unit for detecting the speed of the rotating shaft; a speed setting storage unit that sets and stores a first speed and a second speed lower than the first speed; a speed comparison unit for comparing a speed at the time of the specific position stop instruction with the first speed; a specific position stop action determination unit that determines an action method when the specific position stop instruction is issued based on the comparison result obtained by the speed comparison unit; as well as a specific position stop control unit that controls the servo motor based on the operation method determined by the specific position stop operation determination unit, The specific position stop action determination unit includes a speed instruction generation unit and a movement instruction generation unit. When the comparison result is that the speed at the time of the specific position stop command is higher than the first speed, the speed command generation unit and the movement command generation unit generate a first speed command for decelerating to the second speed with a maximum torque, and a first movement command for stopping at a target position based on an acceleration during deceleration obtained from the speed detected by the speed detection unit or a predetermined acceleration, When the comparison result shows that the speed at the specific position stop command is lower than the first speed, the speed command generating unit and the movement command generating unit generate a second speed command for decelerating at a predetermined deceleration rate and a second movement command for stopping at a target stop position based on the second speed command. The specific position stop control unit controls the servo motor based on the first speed command and the first movement command, or the second speed command and the second movement command generated by the speed command generation unit and the movement command generation unit.

2. The servo motor control device according to claim 1, wherein: The servo motor is configured as an induction motor. The specific position stop operation determination unit comprises: a current detection unit that detects a current of the induction motor; and a magnetic flux calculation unit for obtaining the magnetic flux based on the current value detected by the current detection unit, The speed command generating unit and the movement command generating unit generate the second speed command for decelerating at the prescribed deceleration rate after correcting the pre-set deceleration rate based on the magnetic flux at the start of deceleration, and the second movement command for stopping at the target stop position based on the second speed command, when the speed at the specific position stop command is lower than the first speed so that deceleration is performed at the prescribed deceleration rate.

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