JPH0682303B2 - Moving speed controller - Google Patents

Description

The present invention relates to a control device for a moving speed when an object is moved to a predetermined position by a motor or the like.

(Prior Art) Speed control of a motor, etc., according to the following speed control curve,
It is known that there is little vibration and the movement can be completed in a short time.

FIG. 2 (a) shows the above-mentioned speed control curve, (b) shows the acceleration a, and (c) shows the differential value j of the acceleration a (hereinafter referred to as jerk j). This speed control curve is as shown in the figure.
It is divided into an acceleration region p, a constant velocity region c, and a deceleration region m, and required times T _p , T _c, and T _m are allocated to each.
The acceleration region p and the deceleration region m are τ _p1 , τ _p2 , and
τ _p3 (τ _p1 + τ _p2 + τ _p3 = 1) and τ _m1 , τ _m2 , τ
It can be divided into three sections with a ratio of _m3 (τ _m1 + τ _m2 + τ _m3 = 1). Note that the subscripts p and m are omitted and τ
_It may be expressed as _i (i = 1,2,3). For the control target velocity v, the moving distance s, the acceleration a, and the jerk j, if it is easier to understand which of the above-mentioned intervals is the value, then v _i , s _i , a _i, and j _i (i = Add subscripts such as 1,2,3). In addition, the maximum values of the speed v _i and the moving distance s _i are respectively set as the section arrival speed V _i (i = 1,2,3) and the section arrival distance S _i.
(I = 1,2,3), and the elapsed time of each section is t _i (i = 1,2,3)
3) The maximum value of the acceleration a is the maximum acceleration A. The total elapsed time t is the starting point for the acceleration region p.
The value is from p ₀ , and the deceleration area m is from the end point m ₀ . Then, the speed control curve of FIG. 2 can be expressed by the following equation, as is well known. The following formulas can be applied to both the acceleration side and the deceleration side, so they are usually expressed without distinction.
When distinction is required, the acceleration side is indicated by p and the deceleration side is indicated by the suffix m.

i) In the case of 0 ≦ t ≦ τ ₁ T, (t ₁ = t) V ₁ = v ₁ (τ ₁ T), S ₁ = s ₁ (τ ₁ T) (5) ii) τ ₁ T <t ≦ (τ ₁ + τ ₂ ) T, (t ₂ = t−τ ₁ T) In the case of j ₂ (t ₂ ) = 0 (6) a ₂ (t ₂ ) = A (7) v ₂ (t ₂ ) = A _t2 + V ₁ (8) iii) (τ ₁ + τ ₂ ) T <t ≦ T, (t ₃ = t (τ ₁ + τ ₂ ).
In case of T) V _p3 = V _m3 = v ₃ (τ ₃ T), S ₃ = s ₃ (τ ₃ T) (15) iv) For T ≦ t ≦ T + T _c j = 0 (16) a = 0 (17) v = V _max (18) s = S ₃ + V _max (tT) (19) Accordingly, the moving speed v with respect to the moving distance s is obtained by the above-mentioned equations, and a drive output proportional to this is generated, and
It is only necessary to detect the current speed and feed it back, and always perform control according to the above-mentioned control curve. in this case,
In many cases, it is desired to change the parameters in each of the above-mentioned formulas each time depending on the purpose of use or driving conditions and calculate the most suitable speed control curve for control. However,
Since such a calculation is extremely complicated, it was practically impossible.

(Purpose) The present invention has been made to improve such drawbacks.

(Summary of the Invention) In order to achieve the above object, in the present invention, the above-mentioned speed control curve is used by making it dimensionless / normalized, and common items that do not differ under operating conditions are taken out and calculated in advance. By storing this, the control target speed can be easily calculated.

(Principle of operation) In order to dimensionlessly normalize the velocity v and the distance s of each equation in the cases (i), (ii), and (iii) described above. far. here Then the function f _i is Can be expressed as Also g _i is Can be expressed as Also for V _i S _i , Can be expressed as However And

First, when v _i is calculated from equations (21) and (22), However, F _i = f _i (g _i ^-1 ), and if the reaching speed V _i , the reaching distance S _i and the function F _i are known in advance, the control target speed v _i for the moving distance s _i can be obtained. . Therefore, the actual speed of the motor to be driven can be feedback-controlled to perform accurate speed control. For this purpose, it is necessary to know the value of F _i in advance. FIG. 3 shows the process of creating the F _i table from the f _i and g _i tables.

In the figure, the f _i table is obtained by using the equations (24), (25) and (26). The values of f _i for the 256 values of ζ up to are obtained and stored as digital data having a resolution of 15 bits. Next, the g _i table first defines a set of τ _i , and this τ _i
(27), (28) and (29) are used to calculate the g _i values for 256 ζ as digital data with a resolution of 15 bits, and store them, as in the case of f _i above. Is. Therefore, if τ _i is different, so is the g _i table.

From the f _i table and g _i table thus obtained, F _{i
^{= F i (g i -1)}} , i.e. for various Naru value of g _i, the F _i table showing the values of f _i corresponding to ζ give them g _i, obtained by such operation of the Figure 3 You can

That is, first, from the g _i table of FIG. The two values closest to the true value of ζ corresponding to (n = 1,2, ... 256) (M = 1,2, ... 256) And ask. Then these two approximations Corresponding to From the f _i table in FIG. 3 (b). From these values, the value of f _i (ζ) with respect to the true value of ζ can be obtained by the following linear approximation formula.

Thus The value of f _i for can be obtained with a resolution of 15 bits. Next, by obtaining the values of g _i and f _i for all the values of n, the F _i table can be obtained as shown in FIG.

Using the F _i table thus obtained, the motor speed v _i for each distance s _i can be found by the equation (38). To control the moving speed of the sub connexion object, while measuring the moving distance s _i of every moment, obtains the control target speed v _i for the s _i, such that the actual object movement speed matches the speed v _i Feed back control is sufficient.

When performing the speed control as described above, the maximum values V ₃ and A of the speed v and the acceleration a are set within the range of the maximum value determined in consideration of the surrounding conditions, the capacity of the driving source, etc. It is necessary to move safely to the target. Therefore, various concrete control methods are conceivable, but in any case, in order to perform speed control, it is first necessary to know the reaching speed V _i and the reaching distance S _i in each section. For this purpose (30)
The interval ratio τ _i , the maximum acceleration A, and the required time T must be known in advance as shown in the expressions and (31).

First, the section ratio τ _i needs to be individually determined according to the characteristics of the drive source such as the motor used or the power transmission mechanism. Next, the maximum acceleration A may be fixed to the maximum allowable value, and the required time T may be determined based on this A. In this case, the required time T can be shortened,
It is convenient because it moves quickly, but in the case of short-distance movement, the rate of change j of acceleration becomes too large, so
There is also a disadvantage that vibration and impact during movement become large. Alternatively, the required time T may be fixed and the maximum acceleration A may be determined based on this T. However, in this case, since the required time in the acceleration / deceleration period P, m is constant regardless of the size of the moving distance, it is disadvantageous when moving a short distance.

In the examples described later, in order to improve these points as well Since the control is performed so as to be constant, the operating principle of the embodiments described later will be described below.

First , The maximum value of the jerking j is expressed as j _O because it occurs when t = 0 from the formula (1), and the minimum value is expressed by the formula (11) when t = T (that is, t ₃ = τ ₃ T). When it is expressed as j _T , Therefore, as described above By making constant, j _O and j _T can be made constant.

Then, the constant J can be calculated using equation (30). Can be written.

By the way, in the embodiments described later, in order to reduce the amount of calculation each time, first, the maximum values of the speed and acceleration that can be considered within the range of the intended purpose for the time being are set in advance, and these are set as the absolute maximum speed V _MAX and the absolute maximum. The acceleration A _MAX is set, and the section ratio τ _i is also determined in advance, and various parameters are calculated in advance from these values. Next, according to the actual purpose of use, each time the vehicle is moved, the speed V _max (≦ V _MAX ) is designated according to the moving distance S and the surrounding conditions, and necessary calculations are performed.

Therefore, for the above constant J as well, the equation (43) is changed to It was transformed and asked in advance. Therefore, the above-mentioned absolute maximum acceleration A _MAX , absolute maximum speed V _MAX, and section ratio τ _i
When determining the value, make sure that the jerks j _O and j _T calculated by the equation (41) using the constant J in the equation (44) do not exceed the maximum value determined according to the conditions of the driving mechanism or the driven body. Need to consider.

Thus By fixing to an appropriate value, j _O and j _T can be fixed to a value as large as possible without causing a problem. Further, as described above, the required time T and the maximum acceleration A can be relatively freely set to the optimum values on the basis of the moving distance S and the maximum acceleration V _max (≦ V _MAX ) designated each time.

Next, using the above constant J, according to equations (30) and (31), Also, from Eqs. (15) and (45), V ₃ = D _p3 J _p T _p ² = D _m3 J _m T _m ² (47).

Here, if T (T _p , T _m ) in the equations (45) and (46) is known, V _i and S _i are determined, and the equation (38) can be determined.
Hereinafter, T will be obtained.

Consider the case where there is no constant speed region now. In this case, S = S _p3 + S _m3 Therefore Substituting this result into equation (47) here Is. Therefore (I) Now, if V ₃ obtained from Eqs. (51) or (52) and Eq. (47) is V ₃ <V _MAX , T and T _m are given by Eqs. (51) and (52), respectively. , In this case, it is not necessary to have a constant velocity area.

(Ii) Next, the calculated V ₃ given as described above is V ₃ ≧
If it is V _max, the actual speed V ₃ must be a V ₃ = V _max so must not exceed V _max. Therefore, it is necessary to supplement the shortage of the moving distance by adding a constant velocity region. Therefore, in this case, since V ₃ in the equation (47) is set to V _max , from the equation (47), Thus, V _pi , V _mi , S _pi, and S _mi are (4) according to the times T _p and T _m obtained by the equations (51), (52) or (54), (55).
Since it is calculated from the equations (5) and (46), the relationship between the velocity v and the distance s is determined from the equation (38), and the velocity control can be performed.

(Embodiment) FIG. 1 shows an embodiment of the present invention. In the figure, the data from the initial constant input unit 1 is added to the initial calculation unit 2, and the calculation result is added to the section arrival value calculation unit 4 together with the data from the positioning command amount input unit 3. The calculation result of the section arrival value calculation unit 4 is added to the speed calculation unit 5 together with the data from the area determination unit 6. The output of the speed calculator 5 is applied to the motor 7 via the differential amplifier 8. The motor 7 is provided with a tachogenerator 9 that detects the speed and a motor encoder 10 that generates a pulse for each rotation of the motor 7. The output of the tachogenerator 9 is applied to the differential amplifier 8. The output of the motor encoder 10 is added to the area determination unit 6.

The operation of the above configuration will be described. Section ratio τ _i , absolute maximum acceleration A _MAX and absolute maximum velocity V in the initial constant input section 1
_MAX is set.

In the f _i table calculation unit 27 of the initial calculation unit 2, (24) (25)
And the f _i table is created from equation (26). In addition, constant calculation section
In 21 and 22, the set interval ratio τ _i
To (34) and (35) to (37) to obtain constants D _i and E _i , and the table computing unit 26 uses the formulas (27) to (29) to create a g _i table. Further, the constant calculation unit 23 obtains the constant J from the constant D _i , the absolute maximum acceleration A _MAX and the absolute maximum speed V _MAX from the equation (44). In the constant calculators 24 and 25, the constant J,
The constants K and γ are obtained from D _i and E _{i by the} equations (49) and (50), respectively. On the other hand, in the table calculation unit 28, g _i
A F _i table is created from the table and the f _i table.

The k, γ, D _i , E _i, and J thus obtained are calculated by the required time calculation unit 41 of the section arrival value calculation unit 4 in the positioning command amount input unit 3
Using the moving target distance S from and the maximum speed V _max , (5
The required time T (acceleration required time T _p or deceleration required time T _m ) is calculated by performing the operations according to the equations (1) and (52) and the equations (54) and (55). The section arrival speed V _i is obtained from T, D _i and J, and the section arrival distance is obtained from T, E _i and J.
S _i is required.

On the other hand with current travel distance s obtained from the encoder 10 in the area decision unit 6, block 61, first distance s _m from the target position to the current position, i.e., determining the difference between the movement target distance S and the current travel distance s. Next, in the case of 0 ≦ s ≦ S _p1 , S _p1 <s ≦ S _p2 and S _p2 <s ≦ S _p3 , i = 1, i = 2 and i = 3 of the acceleration region P at the blocks 62, 63 and 64. If s> S _p3 and s _m > S _m3 , it is determined that the constant speed region c is in block 68, and 0 ≦ s _m ≦ S _m1 and S _m1 <s _m ≦
When S _m2 and S _m2 <s _m ≤ S _m3 , it is determined by blocks 65, 66 and 67 that i = 1, i = 2 and i = 3 of the deceleration region m, and the region data P _i , c and m _i are output. s If _m = 0 is determined that reaches the movement target position, the motor is stopped is transmitted to a known Motarotsuku circuit 11. The area determination data P _i , m _i and c described above
Is added to the data selectors 53 and 54, selects the data of the corresponding section from the reaching speed V _i and the reaching distance S _i from the section reaching value calculation unit 4, and respectively selects the target speed calculating unit 51.
And g _i calculation unit 52. Using the section reach distance S _i thus selected and the moving distance s from the encoder 10, the g _i calculator 52 calculates the formula (22) to obtain g _i . The value of g _i thus obtained is added to the F _i table 28, and the corresponding hourly F _i data is extracted,
It is added to the target speed calculation unit 51. The target speed calculation unit 51 calculates the formula (38) using the F _i data and the data of V _i selected as described above to generate the control voltage according to the control target speed v, and the differential amplifier Add to 8. When the region determination data is c, it is in the constant velocity region, and therefore the control target velocity v is kept at the maximum value V ₃ in the acceleration region. In the differential amplifier 8, the voltage according to the current speed given from the tachogenerator 9 is compared with the control voltage, a motor drive current is generated according to the difference, and the rotation speed of the motor 7 becomes the control target speed v. To control. Note that each of the above calculations can be easily performed by a microcomputer.

In this way, the interval ratio τ which is considered to be the best in normal use
_i , the absolute maximum velocity V _MAX and the absolute maximum acceleration A _MAX which should not be increased any more, are given first, and various parameters are calculated in advance by this, so they are given for each normal use. Since the data is only the target distance and the maximum practical speed close to the usage condition, the calculation speed is extremely fast, and accordingly the response speed is also fast.

(Effects of the Invention) As described above, according to the present invention, by storing a simple table, it is possible to perform speed control based on each optimum speed control curve under various conditions.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIGS. 2 (a), (b) and (c) are diagrams showing an example of a speed control curve,
FIG. 3 is a diagram for explaining the principle of the present invention.

Claims (1)

[Claims] 1. For driving a driven object, the time dependence of driving speed, acceleration, or jerk is represented, and the speed control curve is formed by a series of acceleration increasing section, constant acceleration section, and acceleration decreasing section. In a speed control device for controlling the drive speed of a driven object, the drive speed is v, the drive amount is s, and the maximum values of the drive speed in each section are V ₁ , V ₂ and V _3, and The reached value of the driving amount of each section
Let S ₁ , S ₂ and S ₃ be the initial values V ₀ and
S ₀ is 0, the required time for all the above sections is T, and the required time for each section is τ ₁ T, τ ₂ T and τ ₃ T (τ ₁ + τ ₂ + τ ₃ = 1), and the progress in each section Let ζ be a variable that is dimensionlessized and normalized by time t / τ _i T, and let ζ be a function f _{i of} ζ that represents the driving speed obtained by dimensionlessizing and normalizing from the above speed control curve.
(Ζ) and the function g _i (ζ) of ζ that represents the drive amount, When Means for storing the F _i table calculate the value of F _i to be for different Naru value of g _i, means for detecting a driving amount s, the value of the function g _i in accordance with the driving amount s A means for calculating, a means for reading the value of F _i corresponding to the calculated value g _i from the F _i table, and using this read F _i , A moving speed control device comprising: means for calculating the speed v corresponding to the driving amount s; and means for driving the driven object according to the speed v.