JPS60112106A - Drive control method of moving mechanism - Google Patents

Abstract

PURPOSE:To move a mobile body in the shortest time even if a small positioning is conducted frequently by selecting the optimum reference table out of plural reference tables, generating a command pulse based thereupon and controlling a servomotor so as to move the mobile body. CONSTITUTION:A command pulse train generating means 7 stores a reference table representing the relation of reference mobile time - reference mobile amount based on the characteristic of plural reference acceleration/deceleration curves so as to move smoothly over the entire region from the start point to the end point via the maximum speed and plural reference tables representing the relation of reference mobile time - reference mobile amount based on the characteristic of plural acceleration/deceleration curves similar to the reference acceleration/deceleration curve set in response to the mobile amount shorter than the reference mobile amount to a table memory 12 in advance and selects the optimum reference table moving the mobile body in the shortest time in moving the body by a predetermined mobile amount. A command pulse train is generated based thereupon and given to a position controller 8 so as to control the servomotor M thereby moving the mobile body.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present application relates to a digital servo type drive control device for a moving mechanism that moves a moving body of the moving mechanism (for example, an arm of a robot) at high speed and smoothly.

BACKGROUND ART Conventionally, speed positioning control using a digital servo using an electric servo motor has been performed to drive and control a moving body of a moving mechanism such as a robot arm or a table of an NG machine tool. For example, linear acceleration/deceleration is used as a speed positioning control method, but there is a problem in that the speed change is not smooth and therefore a large impact is applied to the moving body.

In order to solve these problems, a system has been proposed in which speed positioning is performed based on a speed curve that smoothly changes the motion of a moving object over the entire range from its starting point to its maximum speed to its end point. ing. This method approximates and digitizes a displacement curve showing the relationship between the reference moving time Tm and the reference moving claw Sm as shown in FIG. This bit string is divided into 8 bits and stored in memory (this is called a reference table), and this is sequentially extracted at fixed time intervals determined by the reference moving time Tm.If 1 bit data in the reference table is II I B, then If it is IIO'', the servo motor is driven and controlled without generating a pulse. For example, when the amount of movement given to the moving object is greater than or equal to the standard amount of movement Sm (the maximum amount of movement in the standard table), one bit of data in the standard table is checked at regular intervals.
If 1111, pulse is generated, if u Ou, pulse is not generated, and when the acceleration completion position on the reference table is reached, if it is larger than the reference moving claw Sm, the number of pulses corresponding to the difference is generated at the pulse interval at the time of acceleration completion. and then move at a constant speed, and then again according to the reference table until the deceleration is completed. Furthermore, when the amount of movement of the moving body is smaller than the reference amount of movement Sm (FIG. 1(b)), known interpolation processing is repeated for a certain period of time to reduce the amount of movement.

However, the standard table prepared in advance in this way is
, and the amount of movement is the standard amount of movement Sm in this reference table.
If it is smaller than j1!, interpolation processing is performed, so the travel time is always j1!, regardless of the amount of travel. , the mold movement time Tm is required, so there is a drawback that a large amount of time is required when positioning with a small movement amount is frequently performed.

Purpose and Summary The present invention aims to eliminate the drawbacks of the above-mentioned prior art. Preliminary storage means includes a plurality of reference tables indicating a relationship between a reference travel time and a reference travel amount based on characteristics of a plurality of acceleration/deceleration curves similar to the reference acceleration/deceleration curve set corresponding to short travel distances. In order to move the moving object by an arbitrary amount of movement, the optimum reference table that allows the moving body to move in the shortest time is selected from among the plurality of reference tables, and the command pulse is generated based on this optimum reference table. It is characterized by generating a servo motor and moving the moving object.
The object of the present invention is to provide a drive control method for a moving mechanism that can move the moving mechanism smoothly and in the shortest possible time even when positioning is frequently performed smaller than the maximum reference moving amount.

Embodiment As shown in FIGS. 2 to 3, 1 is a slide table mechanism exemplified as a moving mechanism, and a slide table 4 is attached so as to slide on two guide rods 3.3 of a main body 2. The slide table 4 is further screwed into a feed screw rod 5. Both ends of the feed screw rod 5 are rotatably supported by the main body 2, and one end is connected to the rotating main shaft of the servo motor M via a joint 6.

Next, a position and speed control device for driving and controlling this slide table mechanism 1 will be explained. The position speed control device includes a central processing unit 9, a program memory 10, and a calculation memory 1.
1. A command pulse train generating means 7 composed of a known microcomputer including a table memory 12, an input/output device 14, a bus 13 connecting these, etc., a pulse signal discriminator 15a, a subtracter 15b, a position deviation counter 16, D
/A converter 17, servo amplifier 18, rotation speed detector 1
9, a digital servo positioning control device 8 equipped with a speed loop and a position loop servo system including a rotation speed detector 20;

Next, the table memory 12 will be explained. The reference acceleration/deceleration speed curve that now reaches the maximum speed Vm is set as shown in FIG. 4(a), and by integrating this basic acceleration/deceleration curve, the reference movement shown in FIG. 5(a) is obtained. Time Tm
- A curve of the reference movement amount S rn is obtained. Corresponding to the movement amount Tn that is shorter than the reference movement time Tm, a plurality of acceleration/deceleration speed curves similar to the reference acceleration/deceleration speed curve, that is, the time axis and the speed axis are reduced, should be set, for example, as shown in FIG. 4(b). By integrating this curve, a curve of reference travel time Tn-reference travel amount Sn shown in FIG. 5(b) is obtained. The several reference travel time-reference travel amount curves (m displacement curves) determined in this way are digitized to approximate them, and converted into '0' and 'l I II signals.
m reference tables Tat (n=1.2,...m) are stored in advance in the table memory 12 (ROM) as bit strings.
(Figure 6). Next, a comparison table prepared for selecting the optimal standard table from among the m standard tables will be explained. First, among the m acceleration/deceleration curves, the nth reference travel time (acceleration/deceleration time) Tn and the maximum speed Vn are similar to the reference acceleration/deceleration curve (Figure 4 (a)), so Tn '= (n/m) ・Tm (1) Vn=(n/m
)・V m (2) (n=1.2,...m) Also, the amount of movement is Sm=-Vm-Tm (3) Sn=-Vn-Tn (4) (k is Constant) From (1) − (4), S n = (n /, m)”
・S m (5) Now, the movement amount S is the movement amount Sn and Sn
+1, as can be seen from FIG. 9 which shows the relationship between the travel time and the amount of movement, the moving claw S is at the boundary moving claw Sc.
If it is smaller, the n-th reference table Tan may be used, and if it is larger, the (n+1)-th reference table Tan+1 may be used.

Therefore, To+1=Tn+(Sc-3n)/Vn (6)(1)
Substituting (5) into (6), S c = '(n (n + 1/k)/nr) ・S
m (7) Here, k is the maximum speed of the moving claw during acceleration/deceleration divided by the acceleration/deceleration time, and takes a value smaller than 1, and it is usually appropriate to set it to = 0.5. Now, substitute k”0.5 into (7) and get Sc= (n(n+2)/nf) ・Sm (8)(n
= 1.2,...m) From equation (8), the relationship between the amount of movement and the number (n) of the selected standard table is obtained as shown in Table 1, and in order to compare in this way The comparison values corresponding to each n are stored in advance in the table memory 12 (ROM) as a comparison table as shown in FIG.

Table 1 In addition, parameters corresponding to each reference table stored in the table memory 12, namely, reference movement amount Sn, reference movement time Tn, acceleration completion time Tvn (n is 1...
. . m) is stored in advance in the table memory 12 as a table parameter memory shown in No. 8a.

Next, from among the m reference tables described above, the optimum reference table is selected that allows the mobile object 4 to move the amount of movement given (or reduced as a result of calculation) in the shortest time. The procedure will be explained with reference to the flowchart shown in Figure 10. When the program starts, in step A, the initial value of the table counter of the comparison table shown in FIG. Step B: Calculate the difference between the origin and the target position, determine the direction of movement based on its sign, and substitute the absolute value (amount of movement) into variable B.
), then the comparison value of the comparison table pointed to by the table counter is assigned to variable A (step C), and when variable A is greater than or equal to variable B in step D, the value of the table counter at that time is assigned to the reference table in table memory 12. with the number of
If not, the table counter is incremented by 1 through steps E and F, and steps C and D are repeated a maximum of (m-1) times to increment the number of the optimum reference table in the table memory 12. Also, from the reference table number stored in this way, from the table parameter memory pointed to by that number,
The selected standard table number; the parameters of the corresponding standard movement amount Sn, standard movement time ゛■゛■, and acceleration completion time T'vn are read out, and further, from the standard movement amount Sn read from the table parameter memory, the given If the amount of movement is large, the amount of movement in the constant velocity area is calculated and written in the calculation memory 11 together with the read parameters.

In this way, one reference table is selected from the m reference tables, and then the movement process of mobile object-4 is started.Next, this movement process will be explained according to the flowchart shown in FIG. 11.12. . In step a, given the amount of movement and
It compares the amount of movement with the reference movement amount of the selected table parameter memory, and if it is equal to or greater than the reference movement amount, each of the loops A to C are executed. The acceleration Louvui performs acceleration processing and displays a pointer (hereinafter referred to as table pointer) indicating the position of 1-pi 1-data in the reference table selected in step b.
It is determined whether the acceleration completion position, that is, the acceleration completion time has been reached, and if so, the process proceeds to step h; otherwise, the process proceeds to step C. In step C, it is determined whether the data pointed to by the table pointer is II 171, and if n 11#, a movement pulse is generated from the output device in step d, and 0''
If so, proceed to step g, adjust the time so that it is the same time as when the movement pulse was generated, and proceed to step e.

In step e, the table pointer is updated to point to the next position by one bit from the currently used position, and then the process proceeds to step f, where the time to repeatedly execute the acceleration Louvui processing becomes a fixed time interval. Make adjustments. This time adjustment is for executing acceleration in a predetermined acceleration time, and the predetermined constant time interval can be determined from the acceleration time and the number of times the acceleration loop is executed. In this way, when the table pointer points to the acceleration completion position, proceed to step h,
Determine whether the uniform velocity area movement amount calculated earlier is O. If it is 0, proceed to step Q. If not, generate a movement pulse from the output device in step i, and reduce the constant velocity area movement amount in step j. The time is adjusted so as to be the same as the processing time of the acceleration loop buoy in step 1, and the processing of the constant-velocity area movement loop processor is repeatedly executed to obtain an equally spaced pulse train and perform one constant-velocity movement. Constant velocity area movement amount is 0
When this happens, proceed to step flood, determine whether the table pointer is at the deceleration completion position, and if not, proceed to step m.
Check the 1-pitch 1-data of the reference table pointed to by the table pointer, and if it is 1'', output a movement pulse at step n, 0''
If so, the time is adjusted in step g, the table pointer is updated in step 0, and the time is adjusted in step P so that the processing time of the acceleration loop and the processing time of the deceleration loop are the same.

In this way, the deceleration loop is repeated and the process ends when the table pointer reaches the deceleration completion position. Next, when the reference movement amount of the selected table parameter memory is larger than the movement amount, the process proceeds to interpolation processing loop 2, and in step r, it is checked whether the table pointer has reached the acceleration/deceleration completion position, that is, the movement time has been completed. If yes, the process ends; if not, the process goes to step S. In step S, it is determined whether the 1-bit data in the reference table pointed to by the table pointer is 1", and if it is 11177, known interpolation processing is performed in step t. , determine whether a pulse is generated in step U, and Y
If it is ES, in step V, a force-transforming device generates a movement pulse. In step W, the table pointer is updated to the next position, and in step W, the time is adjusted so that the processing time of the acceleration loop, constant velocity area movement loop, and deceleration loop is the same no matter which route this interpolation processing loop takes. X, Y,
Z is inserted.

In this way, a pulse train is inputted from the command pulse train generating means 7 to the pulse signal discriminator 15a, and the other inputs of the pulse signal discriminator 15a are supplied with a number of pulses corresponding to the amount of rotation of the servo motor M from the rotation speed detector 20. A pulse signal is applied,
[Pulse signal discriminator] 5a performs discrimination between addition and subtraction of these input signal forces, and guides this to a position deviation counter 16.

The count value of the position deviation counter 16 is calculated by the D/A converter 17.
The signal is converted into an analog signal and added to the subtracter 15b. An analog signal corresponding to the rotational speed of the servo motor M is added from the rotational speed detector 19 to the other input of the subtractor 15b, and the subtracter 15b takes the deviation of these input signals and sends it through the servo amplifier 18. is guided to the servo motor M and driven.

The servo motor M rotates the feed screw rod 5 to move the movable body 4.1. Perform high-speed positioning.

In Fig. 13 (,), each movement amount Sn is calculated by equation (5) with m = 8, and each boundary movement amount SC is calculated by equation (8),
This is shown in a diagram as shown in Fig. 13(b), where in the past it took only the required time T8 even for a movement amount less than the maximum reference movement amount of 88, whereas in the present invention, the maximum reference movement amount If a moving amount of the moving group s8 or less is given, the required time will be less than T8 by following the diagram in (a). Furthermore, the first
FIG. 3(c) is an ideal curve calculated with a large m value, and according to FIG. 13, if m is set to about 8, it can be sufficiently approximated to this ideal curve.

In this example, the comparison table was stored in the ROM in advance and the optimal reference table was selected according to the flowchart shown in FIG. Good too. Furthermore, the time adjustment in the flowcharts shown in FIGS. 11 and 12 can be omitted if interrupt processing using a clock at required time intervals is executed in each movement process. Furthermore, although the movement processing has been explained using software, it can also be realized using hardware.

Effects As described above, the present invention provides a standard travel time based on the characteristics of a standard continuous acceleration/deceleration curve that smoothly changes the motion of a moving object over the entire range from its starting point to its maximum speed to its end point. - A reference table showing the relationship between reference travel amounts and a reference travel time based on the characteristics of a plurality of acceleration/deceleration curves similar to the reference acceleration/deceleration curve, which are set corresponding to travel distances shorter than the reference travel amount. - A plurality of reference tables indicating the relationship between reference movement amounts are stored in advance in the storage means, and when moving the moving body in the moving machine groove by an arbitrary movement amount given in advance, one of the reference tables is selected from among the plurality of reference tables. The optimal reference table that allows movement in the shortest time is selected, command pulses are generated based on this reference table, and the servo motor is controlled to move the moving object. Based on a reference table showing the relationship between reference travel time and reference travel amount, known interpolation processing is performed for travel distances shorter than this reference travel amount, and the moving object is moved by the standard travel time. In contrast, it can be moved in a short time,
Furthermore, since the acceleration and deceleration are approximately the same as the reference acceleration/deceleration curve, the same impact can be applied to the moving body regardless of the amount of movement, and smooth movement can be expected. Furthermore, since a plurality of reference tables are stored in advance in the storage means, the time required for each calculation can be omitted, and the moving body can move faster.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the relationship between the conventional reference movement amount and reference movement time, Fig. 2 is a plan view of the slide table mechanism, Fig. 3 is a block diagram, Fig. 4 is a diagram showing the reference acceleration/deceleration curve, and Fig. 5 is a diagram showing the reference acceleration/deceleration speed curve. The figure shows the displacement curve of Fig. 4, Fig. 6 shows the arrangement of multiple reference tables in memory, and Fig. 7 shows the comparison table.
Fig. 8 is a diagram showing the table parameter memory, Fig. 9 is an explanatory diagram of the amount of boundary movement, Fig. 10 is a flowchart showing the procedure for creating an optimal reference table, and Figs. 11 and 12 are for pulse generation. FIG. 13 is a flowchart showing the relationship between the travel time and the travel amount when m=8. ■...Slide table mechanism, 4...Slide table, 7...Command pulse train generation means, 8...Positioning control device, 12...Table memory, M...Servo motor M Fig. 5 Figure 4 Figure 13 (h) Hashi ↑ Figure 6 Figure 7 Figure 8 Figure 10 Figure 12

Claims (1)

[Claims] The servo motor is equipped with a command pulse train generating means, a speed loop servo system for controlling the rotational speed of the servo motor in buoy back, and a position loop servo system for feedback controlling the rotational speed of the servo motor, and the servo motor is controlled based on the command pulses from the command pulse train generating means. In a drive control method for a moving mechanism that moves a moving object by controlling it, a reference acceleration/deceleration curve is created that smoothly changes the motion of the moving object over the entire range from its starting point to its maximum speed to its end point. A reference table showing the relationship between reference travel time and reference travel amount based on characteristics, and a plurality of acceleration/deceleration speed curves similar to the reference acceleration/deceleration curve set in correspondence with travel distances that are longer than the reference travel amount. A plurality of reference tables showing the relationship between reference travel time and reference travel amount based on the characteristics of are stored in advance in the storage means, and in moving the moving body by an arbitrary travel amount given in advance,
A drive control method for a moving mechanism, characterized in that a reference table that allows movement in the shortest time is selected from among the plurality of reference tables, and a command pulse is generated based on this reference table.