JP3173530B2 - Motor positioning control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor positioning control device having acceleration / deceleration calculation.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional example of a positioning device provided with acceleration / deceleration calculation. In the figure, the positioning control device includes a position command generation device 240 including a motion control command decoding means 201, a position command calculation means 202, and an acceleration / deceleration calculation means 203, and a position control device 220 for driving an electric motor 230. The motion control command decoding means 201 interprets the positioning command and sends the position command calculation means 202 a feed speed F [p
ps] and the travel distance. The position command calculation means 202 outputs a position command to the position control device 220 at a specific cycle (sampling cycle). The purpose of performing acceleration / deceleration calculation is
When the speed component of the position command data changes rapidly (for example, in the form of a non-differentiable discontinuous function), the acceleration component of the command should not exceed the specified maximum acceleration. As an acceleration / deceleration calculation algorithm, an exponential function type shown in a block diagram of FIG. 4 is generally used. In the drawing, ω is an acceleration / deceleration parameter to be set, and the maximum value of the commanded acceleration component changes according to this parameter. For example, Japanese Patent Application Laid-Open No. 2-66012 discloses a servo motor control technique for performing smooth speed control.

[0003]

The setting of the acceleration / deceleration parameter values is very important because any motor must be used at an acceleration below the maximum acceleration that can be generated by itself. Conventionally, a person (operator) directly sets the acceleration / deceleration calculation means as one parameter for the acceleration / deceleration calculation. Conventionally, the relationship between the parameter ω and the maximum value of the acceleration component of the electric motor has not been clarified. For this reason, the parameter value depends on the intuition of human beings, and there is a great problem that the setting varies from person to person although it is an extremely important parameter. Usually, a plurality of positioning control commands (blocks) are executed for the once set acceleration / deceleration parameters. In order to prevent the acceleration component of the motor from exceeding the specified maximum acceleration for a plurality of positioning control commands, it is necessary to set the acceleration / deceleration parameters for the highest-speed positioning operation. With this setting, the acceleration / deceleration parameter becomes unnecessarily small during low-speed feeding, and the time delay due to the acceleration / deceleration operation becomes larger than when the optimum parameter for the speed is set. That is, there is a problem in that unnecessary time is wasted due to acceleration / deceleration, and time required for positioning control is wasted. Reducing the positioning control time is a very important issue from the viewpoint of reducing the tact time of the work. Therefore, it is strongly desired to automatically set the acceleration / deceleration parameters for each positioning control command. To achieve this, acceleration / deceleration parameters (dependent variables) are derived from the acceleration (independent variables) of the motor.
It is an indispensable condition to formulate so that can be calculated. However, as described in the expressions (6) to (9) below, in order to satisfy the above condition, the expression (8)
The equation needs to be solved in reverse. For this purpose, it is necessary to solve equation (9) in reverse (analytically), but this is extremely difficult. Therefore, it has been almost impossible to automatically set acceleration / deceleration parameters for each positioning control command. Japanese Patent Application Laid-Open No. 2-66012 does not disclose anything about this problem. That is, an object of the present invention is to solve all the problems described above.

[0004]

In order to solve the above-mentioned problems, the present invention provides a positioning control device for an electric motor having acceleration / deceleration calculation, wherein the position control means drives the electric motor;
Acceleration / deceleration calculation means for outputting a position command at which exponential acceleration / deceleration is applied according to the acceleration / deceleration parameter ω; position command calculation means for outputting a position command to the acceleration / deceleration calculation means; A motion control command decoding means for outputting to the command calculation means, wherein the feed rate F, the preset maximum acceleration a _max of the electric motor, and the position loop gain Kp of the position control device are converted into a mathematical expression using a constant and an exponential function. The value x (x = ω / Kp) of the acceleration / deceleration parameter ω divided by the position loop gain Kp is calculated using
The acceleration / deceleration parameter ω is obtained by multiplying the acceleration by the Kp. Further, in a motor positioning control device provided with acceleration / deceleration calculation, the feed speed F, a preset maximum acceleration a _max of the motor, and a position loop gain Kp of the position control device are converted into a polynomial expression of up to second order. Calculate a value x (x = ω / Kp) by dividing the acceleration / deceleration parameter ω by the position loop gain Kp,
By multiplying the x by the Kp, the acceleration / deceleration parameter ω
It is characterized by seeking.

[0005]

First, the equation (12) can be derived by approximating the equation (9) with the equation (10). Therefore, the acceleration / deceleration parameter (independent variable) which has been considered to be almost impossible is calculated from the acceleration (independent variable) of the motor. (Dependent variable) can be formulated. That is, for each positioning control command, an acceleration / deceleration parameter is calculated from a feed speed specified by the positioning control command, a preset maximum acceleration of the motor, and a position loop gain of the position control device, and the acceleration / deceleration parameter is calculated as By setting the acceleration / deceleration calculation means, acceleration / deceleration parameters can be automatically set for each positioning control command. Therefore, the time required for acceleration / deceleration for each positioning control operation can be minimized, and the optimum parameters can always be set automatically without depending on the operator.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As an embodiment of the present invention, it is assumed that the motor is rotated at a constant speed, that is, a ramp-shaped position command (the speed component is a step function) is input to the acceleration / deceleration calculation means. First, a relational expression between the acceleration / deceleration parameter ω and the maximum value of the commanded acceleration component is derived. Figure 4 shows a position control system using exponential acceleration / deceleration.
Shown in When sending at a constant speed F [PPS], the position command is a ramp function, so the acceleration of the position control system is

[0007]

(Equation 1)

[0008] The inverse Laplace transform of equation (1) gives the acceleration

[0009]

(Equation 2)

## EQU1 ## To find the maximum value of acceleration,
In equation (2)

[0011]

(Equation 3)

[0012] In equation (3)

[0013]

(Equation 4)

From equation (3),

[0015]

(Equation 5)

At this time, since the maximum value is obtained, if the equation (5) is substituted into the equation (2), the maximum value a _{max of the} acceleration becomes

[0017]

(Equation 6)

## EQU1 ## In equation (6),

[0019]

(Equation 7)

In other words, the maximum value of the acceleration a _max is a _max = FK _P f (x) (8) here,

[0021]

(Equation 8)

## EQU1 ## Equations (7) to (9) are equations for determining the maximum acceleration of the position control system after determining the parameter ω of the acceleration / deceleration filter. When determining the value of the parameter ω so as not to exceed the predetermined maximum acceleration, it is necessary to solve the equation (8) in reverse. For this purpose, it is necessary to solve equation (9) in reverse (analytically), but this is extremely difficult. To solve equation (9) in reverse,
Equation (9)

[0023]

(Equation 9)

Approximate As shown in FIG. 5, α = 0.36
6, if β = 4, the expression (10) almost coincides with the expression (9). Applying equation (10) to equation (8) (f (
x) is replaced by f ₁ (x)) and the maximum acceleration of the position control system is

[0025]

(Equation 10)

## EQU1 ## Solving equation (11) for x

[0027]

[Equation 11]

Is obtained. Next, a first embodiment of the present invention will be described. In FIG. 1, a positioning control device includes a motion control command decoding means 101, a position command calculation means 102, an acceleration / deceleration calculation means 103, and an acceleration / deceleration parameter calculation means 110.
And a position control device 120 for driving the electric motor 130. The motion control command decoding means 101 interprets the positioning command and outputs the feed rate F [pps] and the maximum acceleration a _max [pulse / s ² ] of the motor to the acceleration / deceleration parameter calculation means 110,
The feed speed and the moving distance are input to the position command calculating means 102. The position command calculating means 102 calculates the position data to be moved for each specific cycle (sampling cycle), and inputs the data to the acceleration / deceleration calculating means. The acceleration / deceleration parameter calculation means calculates x using the feed speed F, the maximum acceleration amax, and the proportional gain Kp of the position control device in equation (12), and applies x to equation (7) to calculate the acceleration. Calculate the deceleration parameter ω. The maximum acceleration amax and the proportional gain Kp may be set in advance in the acceleration / deceleration parameter calculation means as calculation parameters. The acceleration / deceleration parameter calculation means sets the calculated value of ω in the acceleration / deceleration calculation means. After setting ω, the acceleration / deceleration calculation means performs the acceleration / deceleration calculation shown in FIG.
Assume position command data. Next, the acceleration / deceleration calculation means outputs the position command data to the position control device 120 at a specific cycle (sampling cycle). Next, the second embodiment of the present invention
An example will be described. In order to simplify the calculation of the expression (12), the expression (12) is expressed by an approximate expression. First,
From equations (10) and (11)

[0029]

(Equation 12)

## EQU1 ## From FIG. 5, 0 ≤ f1 (x) ≤ 0.366
Since α = 0.366 and β = 4,

[0031]

(Equation 13)

Is as follows. The term of the natural logarithm e in the equation (12) is tailored and approximated by a polynomial up to the second order.

[0033]

[Equation 14]

## EQU1 ## Γ in equation (15) is
It is 1/2, but here it is a parameter to minimize the approximation error. FIG. 6 shows the calculation results of equations (12) and (15) when α = 0.366, β = 4, and γ = 1.
As shown in the figure, the approximate expression of Expression (15) can be approximately approximated to Expression (12). That is, the feed rate F [pps], the maximum acceleration amax, and the proportional gain Kp of the position control device are set to (1
X is calculated by applying the equation (2), and the acceleration / deceleration parameter ω is calculated by applying the x to the equation (7). The operation of this embodiment is the same as that of the first embodiment except that the equation (15) is used instead of the equation (12). In Equation (15), α, β, and γ are all constants, so that the exponent and the division can be calculated in advance. Therefore, when calculating the acceleration / deceleration parameter ω as compared with Equation (12), the logarithm or the exponent is used. Does not need to be calculated, and the first using the equation (12)
The calculation is simpler than in the embodiment, and the calculation time can be reduced.

[00035]

As described above, according to the present invention, (9)
By approximating the equation with the simple and highly accurate equation (10), the acceleration / deceleration parameter (dependent variable) can be calculated from the acceleration (independent variable) of the motor, which has been considered to be almost impossible. By setting the acceleration / deceleration parameter in the acceleration / deceleration calculation means, there is a great effect that the acceleration / deceleration parameter can be automatically set for each positioning control command. For this reason, there is also an effect that a human does not intervene in the setting of the acceleration / deceleration parameter, and the individual difference in the set value can be eliminated. Also, according to equation (12),
There is an effect that an optimum acceleration / deceleration parameter can always be calculated for each positioning command. Therefore, there is an effect that the positioning control time is shortened and the tact time of the operation can be shortened. Further, by calculating the acceleration / deceleration parameter by the equation (15), the calculation can be simplified and the calculation time can be shortened as compared with the case of using the equation (12).

[Brief description of the drawings]

FIG. 1 shows a positioning control system according to the present invention.

FIG. 2 shows a conventional positioning control system.

FIG. 3 is a block diagram of exponential acceleration / deceleration calculation.

FIG. 4 shows a position control system with exponential acceleration / deceleration.

FIG. 5 is a comparison of equations (9) and (10).

FIG. 6 is a comparison of equations (12) and (15).

[Explanation of symbols]

 101, 201 Motion control instruction decoding means 102, 202 Position command calculation means 103, 203 Acceleration / deceleration calculation means 110 Acceleration / deceleration parameter calculation means 120, 220 Position control device 130, 230 Motor 140 Position command generation device 240 Conventional position command generation device

Claims (2)

(57) [Claims] 1. A positioning control device for an electric motor having acceleration / deceleration calculation, a position control means for driving the electric motor, and an acceleration / deceleration calculation means for outputting a position command at which exponential acceleration / deceleration according to an acceleration / deceleration parameter ω is applied. When, with the position command calculating means for outputting a position command to the acceleration and deceleration calculating means, and a motion control instruction decoding means for outputting the positioning distance and feed rate on the position command calculating means, preset and the feed rate F The maximum acceleration a _max of the electric motor and the position loop gain Kp of the position control device are
Using the constant and exponential function in the mathematical formula,
The value x (x = ω / K) obtained by dividing the meter ω by the position loop gain Kp
p) is calculated and the acceleration / deceleration parameter ω is calculated by multiplying the x by the Kp.
Positioning control device for an electric motor, characterized in that to determine a. 2. Positioning control of an electric motor having acceleration / deceleration calculation
In the device, The feed speed F and the preset maximum acceleration of the motor
Degree a _max And the position loop gain Kp of the position control device is 2
The above-mentioned acceleration / deceleration parameters
X divided by the position loop gain Kp (x = ω / Kp)
And calculate By multiplying the x by the Kp, the acceleration / deceleration parameter ω
2. The position of the electric motor according to claim 1, wherein
Placement control device.