JPH11259138A - Method for generating control profile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for generating a control profile as an input data to a control system for controlling physical quantities such as a reference speed, an acceleration and a moving distance. SOLUTION: Since a reference profile is previously stored and a control profile is generated in comparisor with the reference profile in this control profile generating method, a control profile showing a smooth secular change can be quickly calculated. In the proposed method, it is also possible to generate a profile for an acceleration section differently from a profile for a deceleration section.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for controlling a motor, and more particularly to a method for generating a control profile for controlling the acceleration speed of a motor.

[0002]

2. Description of the Related Art In most industrial facilities such as industrial robots and semiconductor manufacturing facilities, motor control technology is indispensable. One of the core technologies in such motor control technology is generation of a control profile, which is input data to a control system that represents a physical quantity related to the motor, such as a rotation speed and a rotation amount of the motor.

FIG. 1 is a block diagram showing an example of a conventional motor control circuit.

The motor control circuit shown in FIG. 1 has a motor 11 which operates according to a control signal, and a profile generator which receives position data of the motor 11 and outputs data representing acceleration a, speed v and displacement S of the motor. 12, a subtractor 13 for subtracting the position data of the motor 11 from the displacement S data output from the profile generator 12, a feedback controller 14 for receiving the output of the subtractor 13 and generating a feedback control signal, A feedforward controller 16 that receives the acceleration a and velocity v data output from the profile generator 12 and generates a feedforward control signal; and controls the motor by adding the feedback control signal and the feedforward control signal. And an adder 15 for outputting a signal.

In the motor control circuit as described above,
The operation of the motor 11 is controlled based on the profile data of the speed a, the speed v, and the displacement s generated by the profile generator 12.

[0006] The conventional profile generation methods in the profile generator 12 are roughly classified into two. The first method is software-based, and generates a velocity profile using a function represented by a polynomial. According to this method, a speed profile function composed of a polynomial is stored in advance, and speed data and the like are calculated as a function of time. However, this method has a problem that the time required for performing the calculation is long. That is, it is necessary to increase the order of the polynomial in order to generate a speed profile that shows a smooth change with time, and the calculation time becomes almost exponentially longer. Therefore, its use is almost impossible due to industrial time constraints.

On the other hand, the second method is hardware-based, and generates a speed profile by a digital arithmetic circuit. No. 4,554,49.
No. 7 and 4,555,758. In this method, the calculation of the speed profile can be performed faster than in the first method. However, since the hardware is fixed, the speed profile is also fixed, and particularly, the control profiles in the acceleration section and the deceleration section are changed. There is a problem that you can not. Further, when the time profile of the speed profile is complicated, the calculation time may be long.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to pay attention to the fact that the shape of a control profile is the same in a specific field of application. Motor that can store the characteristics of the target profile, compare the profile to be generated with the reference profile, and use the characteristics of the reference profile to calculate a control profile function having characteristics that change smoothly with time in a short time. Is to provide a control profile generation method.

[0009]

In order to achieve the above object, according to the profile generating method of the present invention, a reference profile relating to distance and speed is defined, and a large number of sets of distances are sampled from the reference profile by sampling.
Obtain velocity data and store the sampled data. Next, the maximum speed ratio K1 and the maximum acceleration ratio K in the reference profile and the profile to be generated.
2, and the conversion coefficient K3 of the moving distance is calculated by the following equation.

[0010]

Equation 7] _{K1 = v max / V max K2} = a max / A max K3 = K2 / K1 2 (A max: maximum acceleration in the reference profile, V _max:
(The maximum speed in the reference profile, a _max : the maximum acceleration in the profile to be generated, v _max : the maximum speed in the profile to be generated).

When an attempt is made to generate a profile for controlling the operation of the motor, the current actual moving distance is converted into the distance of the corresponding reference profile, and the reference profile corresponding to the distance on the converted reference profile is converted. The above speed is read, and the actual operating speed is calculated using the obtained speed on the reference profile.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

FIG. 2 is a graph showing an example of a control profile of the reference acceleration and the reference speed.
A is an acceleration profile expressed as a function of time, FIG. 2B is a velocity profile expressed as a function of time, FIG. 2C is a position profile expressed as a function of time, and FIG. 2B is a diagram illustrating a relationship between a speed and a position illustrated in FIG. 2C and FIG. In general, the control profile of the motor includes an acceleration function a (t), a speed function v (t), a moving distance function s (t), and the like. In a specific application, these control profiles do not change in shape depending on each device, and often differ only in their maximum value and scale on the time axis. Therefore, in the present invention, information of a reference control profile is stored in the form of a table, and a profile to be generated is easily calculated using the reference profile.

The principle of the present invention will be described below with reference to FIG.

In FIG. 2, from time 0 to Ta is an acceleration section, from Ta to Tb is a normal speed operation section, and from Tb to Tb.
It is a deceleration section up to Tc. In the acceleration profile shown in FIG. 2, the inflection points of the acceleration and the acceleration section are each defined as a desired ratio. In FIG. 2A, the inflection point in the acceleration section is represented by αTa and βTa in the acceleration section (0, Ta), and the acceleration at the inflection point is represented by the ratio γ to the maximum acceleration.

In the acceleration section or the deceleration section, the acceleration
A (t), moving distance S (t) and speed V (t) satisfy the following relational expression.

[0017]

KA (t) S (t) = V (t) ²

K is a constant having a different value depending on the shape of the control profile. For example, K is 2 for equivalent velocity motion.

When the profile shape is the same, the constant

[0020]

(Equation 9)

Has a constant value. For a particular application, the acceleration, travel distance, and velocity of the control profile to be generated are a (t), s (t), and v (t), respectively.
Since the shapes of the reference profile and the control profile to be generated are the same, the following relational expression (1) is established between the reference profile and the profile to be generated.

[0022]

(Equation 10)

The above equation (1) can be arranged as the following equation (2).

[0024]

[Equation 11]

Here, A _max and V _max are the maximum acceleration and the maximum speed of the reference profile, respectively, and a _max and v _max are the maximum acceleration and the maximum speed of the profile to be generated, respectively. Therefore, it is possible to make the movement distance or displacement in the control profile to be generated correspond to the displacement in the reference profile.

On the other hand, the speed in the reference profile and the speed in the profile to be generated satisfy the following relational expression (3).

[0027]

(Equation 12)

Accordingly, the speed V (t) of the profile to be generated can be made to correspond to the speed v (t) of the reference profile as shown in the following equation (4).

[0029]

(Equation 13)

In order to simply express the above equations (2) and (4), the maximum acceleration ratio and the maximum speed ratio are defined as in the following equations (5) and (6).

[0031]

[Equation 14]

Furthermore defines another constant K ₃ as the following equation (7).

[0033]

(Equation 15)

Therefore, the following relationships (8) and (9) are established between the reference profile and the profile to be generated.

[0035]

(Equation 16)

Therefore, after mapping the position s (t) of the object or the motor at an arbitrary time to the position S (t) in the reference profile using the above equation (8), the velocity V ( When t) is obtained from FIG. 2D and the calculation according to equation (9) is performed, the velocity v (t) is obtained. The data on the position of the motor, that is, the moving distance is obtained by using another sensor or the like.

On the other hand, as the stored data, FIG.
Instead of the data sampled from the relationship diagram of the speed V and the moving distance S of D, data sampled from the relationship diagram of the acceleration A and the moving distance S can be used. These data are independent of time, and therefore the present invention can be applied to a case where scaling on the time axis differs between the reference profile and the profile to be generated. In the following embodiment, the process of obtaining the speed and the moving distance will be mainly described with reference to the relationship diagram of the speed V and the moving distance S. However, the method of obtaining the acceleration and the moving distance using the relationship diagram between the acceleration A and the moving distance S has a similar process.

Based on the above principle, a preferred embodiment of the control profile generation method of the present invention will be described in more detail. FIG. 3 is a flowchart illustrating a method of generating a profile according to the present invention.

First, in consideration of the maximum acceleration and the maximum speed, a reference acceleration profile, a speed profile based on the reference acceleration profile, and a moving distance profile are defined (block 10).

Then, the moving distance S (t) of the reference profile
Then, the parameter time t is deleted from the velocity V (t) and the distance-velocity data is stored in the memory in the form of a look-up table (block 20). The storage process may be performed by writing to a memory such as hardware, or may be performed by software. Further, the erasure of t may be performed by a mathematical calculation process, or may be performed by sampling a large number of data in the curves of S (t) and V (t). FIG. 2D is a graph showing an example of such a relationship between the moving distance and the speed. In the present embodiment, the stored moving distance−
The speed data is sampled at equal intervals on the moving distance-speed relationship diagram in FIG. 2D. On the other hand, in another embodiment of the present invention, the stored data is sampled using a logarithmic scale graph. As described above, when sampling on a logarithmic scale, the amount of stored data can be reduced.

Next, the maximum speed ratio K1 and the maximum acceleration ratio K between the profile to be generated and the reference profile
2 and a constant K3 are calculated (block 30).

When a control profile for controlling the operation of the motor is to be generated, first, the current moving distance s1 is converted into the distance S1 in the corresponding reference profile using the above equation (8). Yes (block 40). Next, V1 corresponding to the distance S1 is read from the stored table (block 50). Then, the desired speed v1 is calculated from the speed V1 in the reference profile using the above equation (9) (block 6).
0).

By repeating the above process periodically, a control profile in the acceleration section can be generated.

On the other hand, in the deceleration section, in consideration of the fact that the profiles of the acceleration section and the deceleration section are symmetric in most application fields, the acceleration profile is utilized by replacing the moving distance with the remaining distance. A profile can be created. However, assuming that the profile of the deceleration section is different from the profile of the acceleration section, another reference profile can be stored, and a control profile of the deceleration section can be generated using the reference profile.

Although the above description has been made as a process for deriving the speed from the motor position data, the acceleration can be derived from the motor position data in a similar manner.

FIGS. 4A to 4D are diagrams showing more specific examples of reference profiles for explaining the present invention. 4A shows an acceleration profile as a function of time, FIG. 4B shows a velocity profile as a function of time, FIG. 4C shows a profile of a moving distance as a function of time, and FIG. 4D shows the reference profile. Shows the relationship between the speed and the moving distance corresponding to.

On the other hand, FIGS. 5A to 5C correspond to FIGS.
6 is a diagram illustrating an example of a control profile obtained based on a reference profile of D. 5A shows the acceleration profile as a function of time, FIG. 5B shows the velocity profile as a function of time, and FIG. 5C shows the profile of the travel distance as a function of time.

According to the control profile of FIG.
When the speed at 2 is to be obtained, the speed at t = 2 is obtained as follows.

[0049]

[Equation 17]

On the other hand, according to the present invention, the speed at t = 2 is obtained as follows. First, the position at t = 2 is detected by the sensor. At this time, the detected position has the following values.

[0051]

(Equation 18)

Assuming that the detected position is s1, the position s1 on the reference profile corresponding to s1 is obtained as follows.

[0053]

[Equation 19]

Next, the speed V1 on the reference profile corresponding to S1 is read from the memory. Referring to FIG. 4D, it can be seen that V1 has a value of 1/2.

Finally, the velocity at v1, that is, at t = 2, is obtained from the equation (9) as follows.

[0056]

(Equation 20)

That is, the speed at t = 2 obtained according to the present invention has the same value as the speed directly obtained from the profile of FIG. 5B. Although the processing of the present invention has been described using the example of the speed at t = 2, other values, for example, t =
Using the value at 6 gives the same result.

[0058]

As described above, in the control profile generation method of the present invention, only K1 and K1 are required.
2. Only the initial calculations of equations (5) to (7) for calculating K3 and two multiplications by equations (6) and (7) at each sampling time are required. Among them, the calculations of the equations (5) to (7) for calculating the maximum acceleration ratio and the maximum speed ratio need only be performed once at first off-line, so that the speed profile and the acceleration profile are actually obtained at each sampling. The required operation is only two multiplications. Therefore, there is an advantage that the calculation time is shortened.

By storing a large amount of reference profile data, there is an advantage that a smooth control profile of speed or acceleration can be generated. The maximum acceleration in the acceleration section and the maximum acceleration in the deceleration section can be made different from each other, which also has an advantage that a speed profile having a deceleration curve having a shape different from the shape of the acceleration curve can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an example of a conventional motor control circuit.

FIG. 2 is a graph showing an example of a reference acceleration and a reference velocity profile, each of which is composed of A to D;
Is a graph showing an acceleration profile, B is a graph showing a velocity profile, C is a graph showing a displacement or moving distance profile, and D is a graph showing a relationship between speed and moving distance shown in B and C. is there.

FIG. 3 is a flowchart illustrating a method of generating a control profile according to the present invention.

4A to 4D are graphs each showing a specific example of a reference profile for explaining the present invention, wherein A is a graph showing an acceleration profile, B is a graph showing a speed profile, and C Is a graph showing a moving distance profile, and D is a graph showing a relationship between the speed and the moving distance shown in B and C.

5A to 5C are graphs each showing an example of a profile to be obtained based on the reference profile shown in FIG. 4, wherein A is a graph showing an acceleration profile, and B is a graph showing a speed profile. , C are graphs showing the movement distance profiles.

[Description of sign]

 11 Motor 12 Profile Generator 13 Subtractor 14 Feedback Controller 15 Adder 16 Feedforward Controller

Claims (8)

[Claims] 1. A method for generating a control profile, which is input data to a control system representing each physical quantity, for controlling a physical quantity such as a speed, an acceleration, and a moving distance, comprising: (B) obtaining a number of sets of distance-speed data from the reference profile by sampling, and storing the sampled data; and (c) a current actual travel distance. (D) reading the speed on the reference profile corresponding to the converted travel distance on the reference profile; and (e) reading the obtained reference. Calculating the actual speed using the speed on the profile. 2. After the step (b), the maximum speed ratio K1, the maximum acceleration ratio K2, and the moving distance conversion coefficient K3 in the reference profile and the profile to be generated.
The following formula ## EQU1 ## in _{K1 = v max / V max K2} = a max / A max K3 = K2 / K1 2 (A max: maximum acceleration in the reference profile, V _max:
2. The control profile according to claim 1, further comprising a step of calculating the maximum velocity in the reference profile, a _max : the maximum acceleration in the profile to be generated, and v _max : the maximum velocity in the profile to be generated. Generation method. 3. In the step (c), the moving distance on the reference profile is expressed by the following equation: S (t) = K ₃ · s (t) (S (t): moving distance in the reference profile) , S
3. The control profile generation method according to claim 2, wherein the control profile is obtained by (t): current travel distance). 4. In the step (e), the actual speed is calculated by the following equation: v (t) = K ₁ · V (t) (v (t): drive speed, V (t) 3. The control profile generation method according to claim 2, wherein the control profile is determined by a speed in a reference profile. 5. A method for generating a control profile, which is input data to a control system representing each physical quantity, for controlling a physical quantity such as a speed, an acceleration, and a moving distance, comprising: (B) obtaining a plurality of sets of distance-acceleration data by sampling from the reference profile and storing the sampled data; and (c) present actual moving distance. (D) reading the acceleration on the reference profile corresponding to the converted movement distance on the reference profile; and (e) reading the obtained reference. Calculating an actual acceleration using the acceleration on the profile. 6. After the step (b), the maximum speed ratio K1, the maximum acceleration ratio K2, and the moving distance conversion coefficient K3 in the reference profile and the profile to be generated.
The following formula ## EQU4 ## _{K1 = v max / V max K2} = a max / A max K3 = K2 / K1 2 (A max: maximum acceleration in the reference profile, V _max:
6. The control profile according to claim 5, further comprising a step of calculating the maximum velocity in the reference profile, a _max : the maximum acceleration in the profile to be generated, and v _max : the maximum velocity in the profile to be generated. Generation method. 7. In the step (c), the moving distance on the reference profile is expressed by the following equation: S (t) = K ₃ · s (t) (S (t): moving distance in the reference profile) , S
The control profile generation method according to claim 6, wherein the control profile is obtained by (t): current travel distance). 8. In the step (e), the actual acceleration is calculated by the following equation: a (t) = K ₁ · A (t) (a (t): drive acceleration, A (t) 7. The control profile generation method according to claim 6, wherein the control profile is obtained by an acceleration in a reference profile.