JP2006072598A - Servo controller and servo control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a servo controller and a servo control method for suppressing the mechanical vibration of a load or the control vibration of a load without the delay of a command. <P>SOLUTION: This servo controller is provided with a command function preparing means 12 for preparing the difference of location commands in every certain time or a speed command according to the speed or moving amounts of the command by using a command function x being a function changing according to the lapse of time and a function for suppressing the mechanical vibration of a load or the control vibration of the load following the load. The command function preparing means 12 prepares an acceleration/deceleration profile by using the command function x, and calculates an acceleration command when the moving time is within the acceleration time, a command speed when the moving time is beyond a command speed and a deceleration command when the residual moving amounts are below a deceleration distance. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a servo control device and a servo control method using command function creating means for creating a position command and a speed command using a command function according to a load.

FIG. 5 is a block diagram showing an outline of a conventional servo control apparatus according to the present invention.
In FIG. 5, 1 is a microcomputer, 2 is a current amplifier, 3 is a base drive circuit, 4 is a power transistor, 5 is a servo motor, 6 is an encoder that is directly connected to the servo motor 5 and detects the rotational position of the servo motor 5, 7 Is the load.
The servo control device includes a servo motor 5 to be controlled, a load 7 mechanically coupled to the servo motor 5, an encoder 6 for detecting the position of the servo motor 5, and a driver for driving the servo motor 5. It is configured. The driver includes a microcomputer 1, a current amplifier 2, a base drive circuit 3, and a power transistor 4 driven by the base drive circuit 3.
FIG. 6 is a control block diagram showing a conventional servo control device.
In FIG. 6, 5 is a servo motor, 8 is an acceleration / deceleration profile creating means, 9 is a position control unit for controlling the position of the servo motor 5 by a position command signal and a feedback pulse from the encoder 6, and 10 is from the position control unit 9. A speed control unit 11 controls the speed of the servo motor 5 based on the output speed command signal and the feedback pulse from the encoder 6, and 11 is an integration unit. In FIG. 6, Pref is a position command, ω is a speed, θ is a position, Kp is a position loop gain, and Kv is a speed loop gain.
The operation of the servo control apparatus configured as described above will be described with reference to FIGS.
When the microcomputer 1 receives a movement command or feed speed from an external controller or the like (not shown), the acceleration / deceleration profile creating means 8 creates an acceleration / deceleration profile based on the movement command, feed speed and acceleration / deceleration time. A position command is created every time (every sampling time). The position feedback θ from the encoder 6 is subtracted from the position command, and the position control unit 9 performs position control by multiplying the position deviation as the subtraction result by the position loop gain Kp. Next, the speed feedback ω based on the time derivative or difference of the position feedback θ is subtracted from the speed command which is the output of the position control unit, and the speed control unit 10 multiplies the speed deviation which is the subtraction result by the speed loop gain Kv. Speed control. Then, the power transistor 4 is driven via the base drive drive circuit 3 with the output current command and the output of the current control, and the servo motor 5 is controlled.
In this way, the servo control device according to the prior art creates a profile with linear acceleration / deceleration from the movement command, feed speed, acceleration / deceleration time, etc. by the acceleration / deceleration profile creation means 8, and creates an acceleration / deceleration command by adding a filter to it. (For example, refer to Patent Document 1).
In addition, an acceleration / deceleration filter (such as an S-shaped filter or an exponential function filter) that matches the load is further added to the acceleration / deceleration command to obtain a position command or speed command.
Japanese Patent Laid-Open No. 7-121227 (FIG. 6)

However, in the prior art, when the period of the mechanical vibration of the load is long, the mechanical vibration cannot be suppressed unless the acceleration / deceleration time is lengthened. As a result, there is a problem that the command time becomes long. In addition, in order to suppress the mechanical vibration of the load or the control vibration of the load, there is also a problem that the command is delayed by the filter even when an acceleration / deceleration filter that matches the load is placed inside the control.
The present invention has been made in view of such problems, and an object of the present invention is to provide a servo control device and a servo control method capable of suppressing machine vibration and control vibration without causing a delay in commands.

In order to solve the above-mentioned problem, the invention according to claim 1 is a servo control device for driving and controlling a servo motor. The encoder is directly connected to the servo motor and detects the rotational position of the servo motor, and changes with time. A command function that creates a position command difference or speed command for each time according to the amount of movement and speed of the command using a command function that is a function that suppresses mechanical vibration of the load or control vibration of the load. A position control unit that controls the position of the servo motor by a position command signal instructed by the command function generation unit and a feedback pulse from the encoder, and a speed command signal output from the position control unit, A speed control unit for controlling the speed of the servo motor by a feedback pulse from the encoder; To have.
Further, the invention according to claim 2 is a servo control method for driving and controlling a servo motor, wherein the rotation position of the servo motor is detected by an encoder directly connected to the servo motor, and is a function that changes with time. Using command function (x), which is a function that suppresses machine vibration or load control vibration, creates command command creation means to create position command differences or speed commands according to the amount of command movement and speed. The position control unit controls the position of the servo motor using the position command signal instructed by the command function creating means and the feedback pulse from the encoder, and the speed command signal output from the position control unit and the It is characterized in that the speed of the servo motor is controlled by a speed control unit using a feedback pulse from an encoder.
According to a third aspect of the present invention, in the servo control method according to the second aspect, the command function creating means is configured such that the remaining moving distance that is the remaining distance of the moving amount from the current position to the target position is reduced. A step of determining whether or not the travel distance is less than or equal to a deceleration travel distance required from the start to the stop, and if the remaining travel distance exceeds the deceleration travel distance, then whether or not the travel time is greater than or equal to the acceleration time And the step of proceeding to acceleration processing if the acceleration time is less than the acceleration time, and in the acceleration processing, a difference in position command is calculated using a command function, the acceleration / deceleration amount is added to the command speed, and the movement distance is Adding a command speed, calculating a deceleration position command difference using the command function, and adding the calculated deceleration position command difference to a current travel distance to calculate a deceleration distance; When the remaining movement distance exceeds the deceleration distance and is equal to or longer than the acceleration time, the step proceeds to constant speed processing, the step proceeds to deceleration processing when the remaining movement distance becomes equal to or less than the deceleration movement distance, and deceleration processing. Then, calculating the fraction at the time of deceleration at the start of deceleration, calculating the difference of the position command using the command function, and if the difference of the position command is smaller than the fraction at the time of deceleration, the position command Instead of the difference of the step, the step of commanding the fraction at the time of deceleration, and the step of commanding the difference of the position command if the difference of the position command is larger than the fraction of the time of deceleration It is a feature.
According to a fourth aspect of the present invention, in the servo control method according to the second or third aspect, the command function is a function that suppresses two or more mechanical vibrations or control vibrations of the load. It is characterized by that.
According to a fifth aspect of the present invention, in the servo control method according to any one of the second to fourth aspects, the command function is a command function having different acceleration and deceleration.

According to the first aspect of the present invention, since the command function creating means for creating the position command and the speed command using the command function according to the load is provided, there is no delay of the command by the filter, and the load There is an effect that mechanical vibration and control vibration can be suppressed. In addition, since there is no command delay, there is an effect that even if the control gain is increased and the followability is increased, mechanical vibration of the load is hardly generated.
According to the second aspect of the present invention, since the position command and the speed command are created using the command function matched to the load, there is no command delay due to the filter, and the mechanical vibration and control vibration of the load are suppressed. There is an effect that can be. In addition, since there is no command delay, there is an effect that even if the control gain is increased and the followability is increased, mechanical vibration of the load is hardly generated.
According to the third aspect of the present invention, the acceleration / deceleration profile is created using the command function, and the acceleration is within the acceleration time, the command speed is the command speed or more, and the remaining movement is the deceleration speed or less. Therefore, there is no command delay due to the filter, and there is an effect that the mechanical vibration and control vibration of the load can be suppressed.
According to the invention described in claim 4, since the position command and the speed command are created by using a function that suppresses two or more mechanical vibrations of the load or a control vibration, two or more mechanical vibrations, Alternatively, even in the case of a load having control vibration, there is no delay in command due to the filter, and there is an effect that mechanical vibration and control vibration of the load can be suppressed.
According to the fifth aspect of the present invention, since the position command and the speed command are created by using the command function having different acceleration and deceleration, the command delay by the filter can be achieved even when the acceleration and the deceleration are different. There is an effect that the mechanical vibration and control vibration of the load can be suppressed.

  Hereinafter, specific examples of the present invention will be described with reference to the drawings.

FIG. 1 is a control block diagram of the servo control device of the present invention.
In FIG. 1, 12 is a command function creating means. The same reference numerals as those in FIG. 6 indicate the same components as those in FIG.
A feature of the present invention is that it is a function that varies with time instead of the acceleration / deceleration profile creating means 8 for creating an acceleration / deceleration profile using a filter that is a component of FIG. Command function creating means for creating a position command difference or a speed command for each time according to the movement amount and speed of the command using a command function (x) which is a function to suppress the mechanical vibration of the load or the control vibration of the load 12 is provided.
That is, when the microcomputer 1 receives the movement command, the microcomputer 1 calculates the acceleration / deceleration time and the feed speed, creates a position command difference using the command function in the command function creation means 12, and based on this difference, As in the case of FIG. 6, the position control unit 9 performs position control, and the speed control unit 10 performs speed control.

FIG. 2 is a flowchart showing a pre-processing method when a movement command is input in the servo control method of the present invention.
Hereinafter, a preprocessing method for calculating the acceleration / deceleration time and the feed speed for using the command function will be described with reference to FIG.
When the microcomputer 1 receives the movement command and the feed speed, the microcomputer 1 checks whether or not the command speed reaches the given feed speed with the given movement command and feed speed (step ST1). That is, the acceleration / deceleration is added from 0 for the command speed, and the command speed is also added for the moving distance. If the movement command is larger than the movement distance even if the command speed reaches the given feed speed, the command speed has reached the given feed speed by the amount of movement, and the feed speed is the given feed speed. Thus, the acceleration time is also determined (step ST2). If this is not the case, the command speed will not reach the given feed speed based on the amount of movement, the feed speed will be the command speed at that point before reaching, and the acceleration time will also be the time until that point. (Step ST3).

FIG. 3 is a flowchart showing the servo control method of the present invention.
Hereinafter, the servo control method of the present invention will be described with reference to FIG.
Starts creating a position command at every sampling time, and checks whether the remaining travel distance, which is the remaining distance from the current position to the target position, is less than or equal to the deceleration travel distance required from the start of deceleration to the stop. Judgment is made (step ST10). If the remaining moving distance exceeds the deceleration moving distance, it is determined whether or not the moving time is equal to or longer than the acceleration time (step ST20). If the remaining moving distance is less than the acceleration time, the process proceeds to acceleration processing (step ST30). In the acceleration process, a position command difference is calculated using a command function, the acceleration / deceleration is added to the command speed, and the command speed is also added to the moving distance. At this time, the difference of the deceleration position command is also calculated using the command function. Then, by adding the calculated deceleration position command difference to the current movement distance, the deceleration distance at that speed is calculated (step ST40). This is performed for comparison judgment of the remaining movement distance and the deceleration movement distance in step ST10 at the next sampling time.
If the remaining distance of the movement amount exceeds the deceleration distance in step ST10 and the movement time is equal to or longer than the acceleration time, the process proceeds to a constant speed process (step ST50). In the constant speed processing, when the command speed has a decimal part, the fraction of the command speed is added and processed to calculate the command speed (step ST60). For example, XX. In the case of 5 (where X is a number), the fraction of the command speed is also equivalent to 0.5, and “1” is added once to the two times the digit is incremented and output. The constant speed process is repeated every sampling time, and when the remaining moving distance becomes equal to or less than the deceleration moving distance in step ST10, the process proceeds to the deceleration process (step ST70).
In the deceleration process of step ST70, it is determined whether or not deceleration is started (step ST80), and the fraction at the time of deceleration is calculated only once for the start of deceleration (step ST90). The fraction at the time of deceleration is obtained by subtracting the deceleration distance from the remaining distance and adding the feed speed.
A difference in position command is calculated using the command function (step ST100). The difference between the position command and the fraction at the time of deceleration are compared (step ST110). If the difference between the position commands is smaller than the fraction at the time of deceleration, the fraction at the time of deceleration is commanded instead of the difference of the position command (step ST120). If the position command difference is larger than the fraction at the time of deceleration, fraction processing is performed by commanding the position command difference as usual (step ST130).

FIG. 4 is an explanatory diagram showing an example of a command function used in the servo control method of the present invention. In FIG. 4, the vertical axis represents the command x, and the horizontal axis represents time t.
Hereinafter, an example of a command function used in the servo control method of the present invention will be described with reference to FIG.
The command function x shown in FIG. 4 is expressed by the following one expression.
x = Vr / ta * t + f (t) (1)
In Formula 1, Vr is a feed speed, ta is an acceleration time, t is a time, and f (t) is a function that varies with time, and is a function that matches the load, that is, suppresses the mechanical vibration of the load and the control vibration of the load. It is. When it is desired to suppress two or more frequencies, a command function that suppresses two or more mechanical vibrations and control vibrations may be used. Furthermore, command functions having different acceleration and deceleration may be used.

  As described above, the servo control device according to the present embodiment creates a command function for creating a position command difference or speed command using a command function instead of the acceleration / deceleration profile creating means 8 using a filter. When the microcomputer 1 receives the movement command, the microcomputer 1 calculates the acceleration / deceleration time and the feed speed, and the command function creation unit 12 creates a difference between the position commands using the command function. The control unit 9 performs position control, and the speed control unit 10 performs speed control. The servo control method according to the present embodiment is performed by using a command function when creating an acceleration / deceleration profile, and accelerates. Acceleration within time, command speed over command speed, and command for deceleration with remaining movement amount less than deceleration distance are calculated. It is possible to suppress the 械振 motion and control vibration. Further, since there is no command delay, even if the control gain is increased and the followability is increased, it is difficult for mechanical vibration to occur.

  The present invention can also be applied to an apparatus or system such as a machine controller or NC that creates a position command or a speed command for a servo control device at certain time intervals according to a speed, a moving amount, or the like.

Control block diagram of servo control device of the present invention The flowchart which shows the pre-processing method at the time of the movement command input in the servo control method of this invention The flowchart which shows the servo control method of this invention Explanatory drawing showing an example of a command function used in the servo control method of the present invention Configuration diagram showing an overview of a prior art and a servo control device according to the present invention Control block diagram showing a servo control device of the prior art

Explanation of symbols

1 Microcomputer 2 Current amplifier 3 Base drive circuit
4 Power transistor 5 Servo motor 6 Encoder 7 Load 8 Acceleration / deceleration profile creation means 9 Position control section 10 Speed control section 11 Integration section 12 Command function creation means

Claims (5)

In the servo control device that drives and controls the servo motor (5),
An encoder (6) directly connected to the servo motor (5) for detecting the rotational position of the servo motor (5);
This is a function that changes with time, and a difference in position command for each time or a command function (x) that is a function that suppresses mechanical vibration of the load or control vibration of the load, according to the movement amount or speed of the command. Command function creating means (12) for creating a speed command;
A position control unit (9) for controlling the position of the servo motor (5) by a position command signal instructed by the command function creating means (12) and a feedback pulse from the encoder (6);
A speed control unit (10) for controlling the speed of the servo motor (5) by a speed command signal output from the position control unit (9) and a feedback pulse from the encoder (6); Servo control device. In the servo control method for driving and controlling the servo motor (5),
The rotational position of the servo motor (5) is detected by the encoder (6) directly connected to the servo motor (5),
It is a function that changes with time, and there is a command function (x) that is a function that suppresses the mechanical vibration of the load or the control vibration of the load, according to the movement amount and speed of the command by the command function creating means (12). Create position command difference or speed command for each time,
The position controller (9) controls the position of the servo motor (5) using the position command signal instructed by the command function creating means (12) and the feedback pulse from the encoder (6).
The speed control unit (10) controls the speed of the servo motor (5) using a speed command signal output from the position control unit (9) and a feedback pulse from the encoder (6). Servo control method. The command function creating means (12)
A step (ST10) of determining whether or not the remaining moving distance that is the remaining distance of the moving amount from the current position to the target position is equal to or less than a deceleration moving distance required from the start of deceleration to the stop;
If the remaining movement distance exceeds the deceleration movement distance, then determining whether the movement time is equal to or longer than the acceleration time (ST20);
If it is less than the acceleration time, a step (ST30) of proceeding to acceleration processing;
In the acceleration process, a difference between position commands is calculated using a command function (x), an acceleration / deceleration is added to the command speed, and the command speed is added to a moving distance, and the command function (x) is used. Calculating a deceleration distance command, and calculating a deceleration distance by adding the calculated deceleration position command difference to the current travel distance (ST40);
When the remaining moving distance exceeds the deceleration distance and is equal to or longer than the acceleration time, a step of proceeding to constant speed processing (ST50);
A step of moving to deceleration processing when the remaining movement distance is equal to or less than the deceleration movement distance (ST70);
In the deceleration process, a step (ST90) of calculating a fraction at the time of deceleration at the start of deceleration,
Calculating a difference between position commands using the command function (ST100);
When the difference of the position command is smaller than the fraction at the time of deceleration, a step (ST120) of setting the fraction at the time of deceleration as a command instead of the difference of the position command;
The servo control method according to claim 2, further comprising a step (ST130) of using the position command difference as a command when the position command difference is larger than the fraction at the time of deceleration.   The servo control method according to claim 2, wherein the command function (x) is a function that suppresses two or more mechanical vibrations or control vibrations of the load.   The servo control method according to any one of claims 2 to 4, wherein the command function (x) is a command function having different acceleration and deceleration.

Images