JP2010110080A - Motor control apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce damage of a driving system or possibility of deviation of a work due to sudden deceleration in a case of a machine of low permission acceleration of the driving system or a case when the work is held in a control object in a motor control apparatus performing position control for multiplying a position deviation between a position command and a detection position by a position loop gain and calculating a speed command and speed control for calculating a torque command based on the speed command and detection speed, and controlling a servo motor. <P>SOLUTION: An acceleration/deceleration data holding part 16 holding acceleration/deceleration time and maximum sending speed when controlling a position, an acceleration operation part 17 operating acceleration in accordance with acceleration/deceleration time and maximum sending speed and a speed command operating part 18 operating the speed command in accordance with acceleration and detection speed are installed. When an emergency stop switch is pushed or an alarm is caused, a speed command switching part 19 switches the speed command from the speed command Vc from the position deviation computing element 3 to the speed command Vc' from the speed command operating part 18. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention performs position control for calculating a speed command by multiplying a position deviation between a position command and a detected position by a position loop gain, and speed control for calculating a torque command based on the speed command and the detected speed. The present invention relates to a motor control device that controls a position of a control target by controlling a motor.

  FIG. 4 is a block diagram showing an example of a conventional motor control device. The subtractor 2 calculates a deviation between the position command Pc from the position command calculator 1 and the motor position detection value Pm from the motor position detector 13 attached to the servo motor 10, and the position deviation calculator 3 calculates the position deviation. Is multiplied by the position loop gain Kp to output a speed command Vc. On the other hand, the differentiator 15 differentiates the motor position detection value Pm from the motor position detector 13 attached to the servo motor 10 and outputs the motor speed detection value Vm. The subtractor 4 calculates the deviation between the speed command Vc and the detected motor speed Vm and outputs it to the speed deviation calculator 5. In the speed deviation calculator 5, the speed deviation proportional component calculator 6 outputs a speed deviation proportional component based on the speed deviation and the speed loop proportional gain Pv. At the same time, the speed deviation integral component calculator 7 outputs a speed deviation integral component based on the speed deviation and the speed loop integral gain Iv. The adder 8 calculates the sum of the speed deviation proportional component and the speed deviation integral component, and outputs a torque command value Tc. The inverter 9 controls the position of the controlled object 12 driven via the ball screw 11 by supplying a current according to the torque command value Tc to the servo motor 10.

  In machines such as machine tools and industrial robots, when an emergency stop switch is pressed or an alarm is generated, it is necessary to stop the controlled object quickly. It has been.

  FIG. 5 is a block diagram illustrating a stopping method using a dynamic brake. Normally, the U-phase, V-phase, and W-phase motor currents are supplied from the inverter 9 to the servo motor 10. On the other hand, when the emergency stop switch is pressed or an alarm is generated, the dynamic brake resistance circuit switching unit 20 switches the current path from the inverter 9 to the dynamic brake resistors 21a, 21b, and 21c. When the current path is switched while the servo motor 10 is rotating, since the servo motor 10 becomes a generator, a current flows through the dynamic brake resistors 21a, 21b, and 21c. As the current flowing through the dynamic brake resistors 21a, 21b, and 21c is consumed as thermal energy, the motor stops.

  However, in the stopping method using the dynamic brake described above, since the stopping torque is small, the distance to stop becomes long. As a result, there is a problem that the controlled object collides with other parts of the machine and the machine is damaged.

  As a technology to shorten the stop distance, when the emergency stop switch is pressed or an alarm is generated, the speed command is set to 0, and the servo motor generates torque in the direction opposite to the drive direction of the controlled object. Thus, a method for shortening the stop distance is known (see, for example, Patent Document 1).

  According to the above-described conventional technology, the servo motor stops at the maximum torque that can be output, so that the acceleration during deceleration increases and it is possible to stop at a short distance. However, a machine with a low allowable acceleration of the drive system has a problem of causing mechanical damage to the drive system. In addition, when a workpiece or the like is held on the controlled object, there is a possibility that the workpiece or the like is displaced or detached from the holding portion.

Japanese Patent No. 3494855

  The object of the present invention is to reduce the damage to the drive system compared to the prior art even when a workpiece or the like is held on a machine or control target having a low allowable acceleration of the drive system, or to prevent the workpiece from shifting or coming off due to sudden deceleration. To reduce the possibility.

  A motor control device according to the present invention includes a position control that calculates a speed command by multiplying a position deviation between a position command and a detected position by a position loop gain, and a speed control that calculates a torque command based on the speed command and the detected speed. In the motor control device that controls the position of the object to be controlled by controlling the servo motor, an acceleration / deceleration data holding unit that holds the acceleration / deceleration time during position control and the maximum feed speed, and the acceleration / deceleration time In accordance with the maximum feed speed, an acceleration calculation unit that calculates acceleration, and a speed command calculation unit that calculates a speed command according to the acceleration and the detected speed, and when the stop condition is satisfied, Instead of the speed command obtained by the position control, the speed control is executed using the speed command obtained by the speed command calculation unit.

  According to the present invention, even when a workpiece or the like is held on a machine or control target having a low allowable acceleration of the drive system, damage to the drive system is made smaller than before, or the possibility of deviation or disconnection of the work due to sudden deceleration is achieved. Can be reduced.

  FIG. 1 is a block diagram illustrating an example of a motor control device according to an embodiment of the present invention. The same elements as those in the conventional example shown in FIG.

  The motor control device of this embodiment is obtained by adding an acceleration / deceleration data holding unit 16, an acceleration calculation unit 17, and a speed command calculation unit 18 to the configuration illustrated in FIG.

  The acceleration / deceleration data holding unit 16 holds an acceleration / deceleration time Tcon at the time of position control determined in advance by an adjustment operation or the like, and a maximum feed speed Fmax at the time of position control defined by machine specifications. The acceleration calculation unit 17 calculates and outputs an acceleration α according to the acceleration / deceleration time Tcon and the maximum feed speed Fmax from the acceleration / deceleration time holding unit 16. The speed command calculation unit 18 outputs a speed command Vc ′ according to the acceleration α from the acceleration calculation unit 17 and the motor speed detection value Vm from the differentiator 15. When a predetermined stop condition is satisfied, such as when an emergency stop switch is pressed or an alarm is generated, the speed command switching unit 19 determines the speed from the speed command Vc from the position deviation calculator 3. The speed command is switched to the speed command Vc ′ from the command calculation unit 18. When the speed command is switched, the subtracter 4 calculates a deviation between the speed command Vc ′ and the motor speed detection value Vm and outputs the deviation to the speed deviation calculation unit 5. In the speed deviation calculator 5, the speed deviation proportional component calculator 6 outputs a speed deviation proportional component based on the speed deviation and the speed loop proportional gain Pv. At the same time, the speed deviation integral component calculator 7 outputs a speed deviation integral component based on the speed deviation and the speed loop integral gain Iv. The adder 8 calculates the sum of the speed deviation proportional component and the speed deviation integral component, and outputs a torque command value Tc. The inverter 9 supplies the current according to the torque command value Tc to the servo motor 10 to stop the control target 12 driven via the ball screw 11.

In the following, referring to FIG. 2, the acceleration / deceleration data holding unit 16, the acceleration calculation unit 17, and the speed command calculation unit 18 obtain the acceleration / deceleration time Tcon, the maximum feed speed Fmax, the acceleration α, and the speed command Vc ′. An example of the calculation process will be described. The acceleration / deceleration data holding unit 16 holds an acceleration / deceleration time Tcon at the time of position control determined in advance by adjustment work or the like and a maximum feed speed Fmax at the time of position control defined by the machine specifications. The acceleration calculation unit 17 uses the acceleration / deceleration time Tcon and the maximum feed speed Fmax, for example,
<Equation 1>
α = Fmax / Tcon
The acceleration [alpha] calculated in is output. The speed command calculation unit 18 sets the motor speed detection value from the differentiator 15 when the emergency stop switch is pressed or an alarm is generated as V0, acceleration α (calculated by the above formula), time t, speed Using v, for example:
<Equation 2>
v = V0−αt
Then, the speed v is calculated, and this speed v is supplied to the speed command switching unit 19 as a speed command Vc ′. The acceleration / deceleration time Tcon is adjusted in accordance with a case where a work or the like is held on a machine or control target with a low allowable acceleration of the drive system by, for example, trying various acceleration / deceleration times in work such as adjustment work. Make a decision. By determining the acceleration / deceleration time Tcon in this way, it is possible to prevent the acceleration during deceleration from becoming excessively large and becoming unnecessarily small. That is, in a machine having a low allowable acceleration of the drive system, the possibility of causing mechanical damage to the drive system is reduced. Moreover, when a workpiece | work etc. are hold | maintained at control object, possibility that a workpiece | work etc. will slip | deviate or remove | deviate from a holding part is also reduced. Therefore, even when a workpiece or the like is held on a machine or control target with a low allowable acceleration of the drive system, it can be decelerated at an optimal acceleration, and the damage to the drive system is smaller than before or due to sudden deceleration The possibility of workpiece slippage and detachment is reduced.

  In FIG. 1, the subtractor 2 calculates the deviation between the position command Pc from the position command calculator 1 and the motor position detection value Pm from the motor position detector 13 attached to the servo motor 10 to calculate the position deviation. The semi-closed loop control in which the device 3 multiplies the position deviation by the position loop gain Kp and outputs the speed command Vc has been described, but this is only an example. In addition to this, for example, as shown in FIG. 3, the method of this embodiment includes a position command Pc from the position command calculator 1 and a control target position Pl from the linear scale 14 that directly outputs the position of the control target 12. May be applied to the fully closed loop control in which the subtractor 2 calculates the deviation and the position deviation calculator 3 multiplies the position deviation by the position loop gain Kp and outputs the speed command Vc.

  Further, in FIGS. 1 and 3, the linear shaft driven through the ball screw has been described. However, the method of the present embodiment may be applied to a rotary shaft driven through a gear / belt or the like. good.

  As described above, in the present embodiment, even when a workpiece or the like is held on a machine or a control target having a low allowable acceleration of the drive system, it can be decelerated at an optimal acceleration, and damage to the drive system is reduced. It is possible to provide a motor control device that can be made smaller than conventional ones, or can reduce the possibility of workpiece displacement or detachment due to sudden deceleration.

It is a block diagram which shows embodiment of this invention. It is a block diagram which shows embodiment of the acceleration / deceleration data holding | maintenance part of this invention, an acceleration calculating part, and a speed command calculating part. It is a block diagram which shows other embodiment of this invention. It is a block diagram which shows a prior art. It is a block diagram explaining the stop method in a dynamic brake.

Explanation of symbols

  1 Position command calculator, 2, 4 subtractor, 3 Position deviation calculator, 5 Speed deviation calculator, 6 Speed deviation proportional component calculator, 7 Speed deviation integral component calculator, 8 Adder, 9 Inverter, 10 Servo motor , 11 Ball screw, 12 Control target, 13 Motor position detector, 14 Linear scale (control target position detector), 15 Differentiator, 16 Acceleration / deceleration data holding unit, 17 Acceleration calculation unit, 18 Speed command calculation unit, 19 Speed command Switching unit, 20 Dynamic brake resistance circuit switching unit, 21a, 21b, 21c Dynamic brake resistance.

Claims (1)

Servo motor is controlled by performing position control to calculate speed command by multiplying position deviation of position command and detection position by position loop gain, and speed control to calculate torque command based on speed command and detected speed In the motor control device that controls the position of the controlled object,
An acceleration / deceleration data holding unit that holds the acceleration / deceleration time and maximum feed speed during position control;
An acceleration calculator that calculates acceleration according to the acceleration / deceleration time and the maximum feed speed;
A speed command calculation unit that calculates a speed command according to the acceleration and the detected speed;
When the stop condition is satisfied, the speed control is executed using the speed command obtained by the speed command calculation unit instead of the speed command obtained by the position control. Control device.

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