JPS62171016A - Positioning controller - Google Patents

Abstract

PURPOSE:To shorten positioning time and to improve positioning accuracy by raising a loop gain as deviation is smaller so that a position deviation voltage generating the prescribed motor torque can be outputted. CONSTITUTION:In terms of position control, gain data in a gain setting table 39 is read out every fixed time in accordance with a value counted by a counter 41 counting a timing clock from an oscillator 40, and stored in a register 36. A multiplier 34 multiples an analog position deviation voltage outputted from a D/A converter 5 by the gain data stored in the register 36 by a voltage that a D/A converter 35 converts into analog. Thus the position deviation voltage is multiplied by the gain data. Namely, the loop gain of a control system is changed according to the gain data. Thus the positioning time can be shortened and constant position deviation can be reduced.

Description

Detailed Description of the Invention [Field of the Invention] The present invention relates to a step-and-repeat exposure device, a semiconductor manufacturing device such as IC Honda, an industrial robot, a positioning bottle for a movable body in an NC machine tool, and an 1100 device. In particular, we aim to correct the influence of disturbances such as load fluctuations and changes in the frictional force of l1%I moving parts, to enable positioning in a short period of time without steady position deviation, and to eliminate the difference in steady position deviation depending on the positioning direction. Possible positioning control [Regarding I device]

[Description of Prior Art] Conventionally, a control circuit of this type of positioning control device for a movable body is configured as shown in FIG. Further, generally, the positioning of the movable body is performed according to a reference target curve such as the solid line in FIG.

In FIG. 21, the speed control section is from a to e,
At a point e when the movable body reaches the vicinity of the positioning target position (stopping target position), the position control is switched to perform final positioning. In the figure, a is the acceleration start point, b is the acceleration end point when the maximum speed is reached and shifts to constant speed drive, C is the deceleration start point, d is the point at which the final speed is reached, that is, the deceleration end point, and e is the speed control The control mode switching point from to position control, f is the positioning completion point.

In FIG. 20, in the speed control mode, the analog switch 6 selects the speed command D/A converter 2, and the speed function generator 1 creates a reference speed curve as shown in FIG. 21 a-e. /A converter 2 obtains the speed command voltage. The closed loop of amplifier 7, motor 8 and speed detector 9 performs speed control by speed feedback control, and D/A change! IA device 2
The movable body 10 is moved at a speed according to a speed command voltage from. Next, the control mode switching position e switches to a position control mode for positioning with higher viscosity, and the analog switch 6
selects the position error output D/A converter 5. Starting from the position deviation counter 4, the 0/A converter 5, the amplifier 7, the motor 8, the movable body 10. The closed loop of position detector 11 forms a positioning feedback control system.

In such a configuration, the shift from the deceleration end position @d (Fig. 21) to the position control switching position e is caused by disturbances such as gain adjustment errors and drifts of the amplifier 7, or changes in the frictional force of the sliding parts. The final velocity section becomes long as shown by the dotted line B in FIG. 21, and it is difficult to keep the positioning time as short as possible in a stable manner.

In addition, the loop gain of each speed and position control system of such a device is constant, and may be affected by factors such as load fluctuations, changes in frictional force of sliding parts, changes in system rigidity, or changes in I11 control. Due to reasons such as the inability to increase the loop gain to prevent the system from becoming unstable, vibration may occur during position control switching, or the steady position deviation (deviation between the target stop position and the actual stop position) is large or the position and There was a drawback that the magnitude of the steady position deviation changed depending on the direction of movement.

OBJECT OF THE INVENTION] An object of the present invention is to reduce the positioning time in a positioning control device in view of the problems in the conventional type described above. A further object of the present invention is to improve positioning accuracy by reducing steady position deviation and changes in steady position deviation due to target position and movement direction.

[Description of Example 1 The present invention will be explained in detail below.

11'i[9 Now, the principle of the first embodiment of the present invention will be explained with reference to FIG. In Figure 21, the horizontal axis is the time (1) axis,
It represents the speed V (hereinafter referred to as speed curve) and position X (hereinafter referred to as ωJ construction curve) of the movable body 10 at each point in time. A reference target curve that is preset before positioning operation, B is an example of an actual curve when the actual speed of the movable body does not match the speed (reference speed) set for the curve due to servo control error, C is a curve obtained when the deceleration start point C' in curve B is corrected to C'' according to the present invention.

The coordinates of each point a-f on the standard target curve A are Acceleration start point a is at position xO1 and time t.

Acceleration end point is position Xl, time t1 Deceleration start point C is position x2, time t2 Deceleration end point d is position x3, time t3 Control mode switching point e is position x4, time t4 Positioning completion point f is position X5, time t5, and each point and its coordinates on the curve B (conventional example) and the track IC (invention) corresponding to each point on the reference target curve A and its coordinates are respectively
' and '' are added. Also, p is the positional deviation at the time of control mode switching, r is the target positional deviation at the start of deceleration, and q is the theoretical positional deviation at which the deceleration should end. These deviations, r and q, are each constant values.Furthermore,
Here, the acceleration time tI-t.

is constant, and the deceleration time is also t3-t2 = t3'-t2
'= j3Lr j2rJ == constant.

By the way, in this type of positioning control device, load fluctuations and f! Due to the change in frictional force, a difference occurs between the reference speed and the actual speed of the movable body 10.

As an example, a case where the actual speed becomes slow as shown by curve B in FIG. 21 will be explained. That is, if the actual speed is equal to the reference speed, the movable body 10 moves on the reference target curve A at a
, b, c, d, e, f, but since the maximum speed actually decreases, the time to reach the deceleration start position x 2 is t2', which is delayed by t2'-t2. In addition, the deceleration time is a constant value (t3-j2=t+"-t2'
), the deceleration end time is t3'. The travel distance in the deceleration section is determined by the standard maximum speed being vb, the actual maximum speed being vb', the standard final speed being vd, and the actual final speed being v.
d', for curve A, (X3-X2) = (vb + vd) x (t3-j2)/for two-curve curve, (X3'-X2') = (vb' + vd') x (t3'-t21 > /2
It is.

Here, vb >vb', vd >vd',
(t3-t2) = (t3'-t2'), the deviation of deceleration end position x 3' from deceleration end target position x 3 is No X: + X3' = ((Vb-vb')
+(vd-Vd')X(1,+-t2)/2 >Q
As shown in the curve, it can be seen that the movable body completes deceleration at point d', which is before the reference deceleration end target position (point d).

Next, it moves at a low speed to the speed/position control mode switching position at the final velocity vd', but since the moving distance has increased by J, the moving time becomes longer, and at point e'(i4') A speed/position switch will occur. After switching to the position control mode, the movable body stops very close to the target position x 5, and positioning is completed (point f', t!j').

Through this process, the actual positioning time t5'
becomes longer than the reference target value t5.

In order to shorten the positioning time, if the error is corrected in the high-speed section between b and c, vd'<vb', and since the travel time is inversely proportional to the speed, it becomes /vd'>J/vb', which is more It can be seen that it can be corrected to a shorter time.

That is, the new deceleration start target position deviation is r'', and r
"= r - J. l is the position of the movable body at the end of deceleration measured as the position deviation m from the stop target position, and the difference between this measured value m and the reference target value q, that is, J = m -q can be obtained.

When deceleration is started based on the new deceleration start target position deviation r'', as shown by curve C in FIG. Although it is slower than t2', the deceleration end position is the same as the standard target curve A x 3, and the moving distance in the final speed section is the same as that of the standard target curve A. The processing time in this section is the actual speed vd' is lower than the reference speed vd, so t
4''-t3''>t4-t3, but in reality, the difference between the actual speed and the reference speed is relatively small, and the moving distance in this section is minute, so the total time required for positioning is t5'' and ts
It will be approximately the same time. On the other hand, if we compare it with curve B when the time point at which this deceleration starts is not corrected, we find that ts" - t
s'=J/vd'-J/vb'>O, and the positioning time is shortened.

FIG. 1 is a block diagram of the first embodiment of the present invention, in which 1 is a speed function generator, 2 is a D/A converter that converts a speed command value into a speed command voltage, and 3 is a target stop position faXs of a movable body. (
4 is a position deviation counter that stores a position deviation value that is the difference between the current position of the movable body and the stop target position stored in register 3;
is a D/A converter that converts the device deviation value into a position Q difference voltage, which is composed of a counter 4; 6 is an analog switch that switches between speed control and position control; 7 is an amplifier that is a servo amplifier; and 8 is a movable A motor drives the body 10, 9 is a motor speed detector such as a tacho generator, and 10 is a movable body such as a slide table or a robot arm. 11 is a rotary encoder, linear scale or laser
13 is a register for storing the position error (error) after the completion of positioning, that is, the steady position error ε; 14 is the register for storing the deceleration end target position (point d); Deviation Faq instead of absolute value x 3
15 is the error value of the actual deceleration end position m at the previous positioning with respect to the deceleration end position uq = m
16 is a latch that stores the deceleration end position m at the previous positioning, 17 is a register that stores the correction value J of the deceleration start position, and 18 is the deceleration start position r (point c) and the speed / A register that stores the position control mode switching position @p (point e), 19 is the current position and switching position rll=r
-J. Also, A+, A2
, A3 is moderately Korean.

Next, the operation of the control circuit shown in FIG. 1 will be explained.

The counters and registers are cleared when a positioning operation is performed for the first time after the power is turned on, and when conditions such as the maximum speed or speed function are changed. The deceleration end target position deviation register 14 can be appropriately set or changed by an operator's input operation or a command from the main device to which this control circuit is applied.

In the circuit J3 of FIG. 1, the movable body stop target position x5 (f
The switching position data p is set in the switching position register 18, and the deceleration end position @q is set in the register 14. In the comparator 19, if the device deviation value constituted by the position deviation counter 4 is larger than the switching position data p output from the switching position deviation register 18, the analog switch 6 is switched to the speed control side, and the contents of the switching position deviation register 18 are changed. Sera 1 at the deviation position r (absolute value X2) of the start of deceleration
At the same time, the speed function generator 1 is reset and speed control is started by this machine. On the other hand, if the current position deviation value is smaller than the switching position data p, speed control is stopped and position it, 11 control, which will be described later, is performed.

During speed control, a speed command voltage is output from the D/A converter 2 based on the speed curve generated by the speed function generator 1, and is sent to the speed servo system (amplifier 7) via the analog switch 6.
, motor 8 and speed detector 9). As a result, the speed and position of the movable body 10 are changed to the second position.
It changes as indicated by a' to e' of curve B in Figure 1. On this occasion,
When the contents of the counter 4 match the contents r of the register 18, the comparator 19 detects this, and the speed function generator 1 responds by starting deceleration. After the motor 8 starts decelerating at point C', the switching position deviation register 18 records the switching position p.
is set, and the position deviation value m of the point d' at which the speed of the movable body 10 reaches the final speed is stored in the register 16.

Subsequently, when the switching position p set in the switching position deviation register 18 and the current position measured by the current position counter match (FIG. 5e), the comparator 19 activates the analog switch 6.
Switch to position control side.

In the position υ control, the position of the movable body 10 is determined with high precision by a closed loop of the position deviation counter 4, the D/A converter 5, the amplifier 7, the motor 8, the movable body 10, and the position detector 11.

After the positioning is completed, the steady position deviation amount ε in the position deviation counter 4 is stored in the correction value register 13. Similarly, the deceleration end target position deviation q of the deceleration end target position deviation register 14
and the deceleration end position deviation m of the deceleration end position deviation register 16.
The difference between the two values is obtained by the differentiator 15 and stored in the deceleration start position correction value register 17. With this first action,
This means that the correction value j for the deceleration end position and the correction value ε for the target stop position are stored.

During the second operation, stop target position register 3, deceleration end target position deviation register 14, and switching position deviation register 1
8 is set with the same values as the first time x 5, q, p, and r. However, among these values, x5 and r are now corrected by adding or subtracting correction values ε and , respectively, by adders/subtractors A1 and A3.

In this case, the new (after correction) deceleration start correction value % r
I+ is determined as follows. In other words, the difference t between the target deceleration end position q and the first actual deceleration end position 1 m =
m-q is determined by a subtractor 15. It is sufficient to correct the deceleration start position by this deviation 11.

Therefore, the new deceleration start position r'' is the value r-4 obtained by subtracting the deviation amount J from the deceleration start position r.

The new target stop position @×5' is the value obtained by adding the deviation ωε obtained by the current position deviation counter 4 and stored in the correction value register 13 to the reference target stop position 6X5×5+ε.

As a result, the results of the first learning are reflected in the second motion, and the motion curve becomes like the two-dot chain line C in FIG. As is clear from the figure, as a result of learning, the deceleration start point is corrected from C' to C'', and the stopping point is changed to f'.
to f n, and the stopping position is also x 5
From the position 1-←ε, it approaches the position ε before, that is, the target stop position x5.

In addition, this control circuit can also compensate for the drift and offset of analog circuits, so it does not require expensive circuitry or high-grade equipment to compensate for these drifts and offsets. Since an operational amplifier or the like is not required, it is possible to reduce the cost of the device.

Note that, at least during the second and subsequent operations, the correction value register 17 is cleared during position control.

FIG. 2 shows a second embodiment of the invention using a computer. In the figure, 20 is a central processing unit (CPU) such as a microcomputer or minicomputer;
1 is a memory device such as ROM or RAM, 22 is an IT B
The i bus 23 is a switching command device for switching the analog switch 6.

Here, the functions of the blocks 1 and 12 to 19 shown in FIG. 1 are replaced by computer software processing.

Next, the operation of the control circuit shown in FIG. 2 will be explained with reference to the flowchart shown in FIG.

At the time of initial drive after power-on or change of setting conditions, the process proceeds from step SA1 to SA2, and each correction value is initialized in step SA2. That is, the deceleration start position correction value, positioning correction value, and number of corrections are zeroed.

In the positioning operation, first, in step SA3, a target value, which is the difference between the target position and the positioning correction value, is calculated. The target position is the sum of the current position and the moving distance, and is the final position where the movable body 10 is desired to be positioned.

Next, the computer outputs a speed command signal based on a speed curve as shown in FIG. 21 to the speed control system via the D/A converter 2' and the analog switch 6, and moves the movable body 10. In parallel with this, the deceleration end position deviation m, control switching position deviation q, and positioning end position deviation ε are read from the count value of the position deviation counter 4' at each timing (steps SA4 to SA14). ).

Calculation of the correction value in step S A 15 is performed using j
(i>=Δx3 (i-1)+(Q-m -Con5
t) /K i ΔX5 (i) - ΔX5 (t -1>+ε/Ki.The calculation of the correction value by this control circuit is, as can be seen from the above formula, after a certain number of corrections. , supplementary iE
The value converges and becomes stable.

Embodiments Prior to explaining the third to B embodiments of the present invention, the principles of these embodiments will be explained.

In the control circuit shown in Fig. 20, the loop gain of the positioning control system is Ko [1/S], the rated torque of the motor 8 is TI) [N-ml, and the cutting feed rate of the motor 8 at the rated rotation speed is Fr [m]. /S1, motor shaft conversion load torque is T
d [N-ml, positioning deviation (steady position deviation) ε [ml is ε> (Fr /Ko ) − (Td /
Tl) ). Further, the loop gain KO cannot be increased because if it is increased beyond a certain value due to the system configuration of the servo system, it will become oscillated and become unstable. For this reason, with the conventional method, the steady position deviation ε could not be lowered below a certain value.

Here, an example of the oscillation limit in a stage positioning control system using a ball screw is shown in FIG. 4 as a relationship between the gain KO and the steady position deviation ε. The solid line indicates the oscillation limit on the anti-motor side, and the dotted line indicates the oscillation limit on the motor side. According to this, the relationship between gain KO and positional deviation ε is expressed as KO=K·ε−H. However, K and P are proportional constants and may change depending on the position.

In the case of the conventional method, the gain is constant after switching from speed control to position control, and the viscosity I! i! The attenuation waveform in a system with friction converges exponentially when the gain is low (for example, gain characteristic a in Figure 5), as shown by a in Figure 6, and when the gain is high (for example, gain characteristic a in Figure 5). b) in the figure converges vibrationally as shown by b in Fig. 6, while drying 1! ! In the case of m, it linearly converges to a constant deviation value. Therefore, if the gain KO is set as large as possible in the stable region according to the positional deviation, and the gain KO is increased over time as shown by the curve ce in Fig. 5, oscillation will not occur and the gain KO will be set as large as possible, as shown in Fig. 6. A response characteristic as shown in curve C can be obtained.

Furthermore, when positioning control is performed using this type of servo circuit, hysteresis occurs in positioning due to the frictional force of the sliding parts and bearings. That is, since the position deviation voltage (command value to the servo amplifier 7) has a linear relationship with the position deviation, the torque generated by the motor 8 due to a minute position deviation cannot overcome the frictional force, and the movable body 1 acts as a dead zone.
There are areas where 0 cannot move. As a solution to this problem, generally speaking, an integral circuit is added to the servo circuit, and the command voltage caused by this minute positional deviation is integrated over time to generate enough motor torque to overcome the frictional force. The deviation is zero. However, the stopping position of the movable body is brought closer to the target stopping position. However, using the integrating circuit in this way increases the positioning time.

Further, as described above, if the loop gain KO of the servo system is increased, the steady position deviation ε approaches zero and the positioning accuracy is improved, but if the loop gain KO is increased, the servo system becomes unstable and may oscillate.

Therefore, in the third to eighth embodiments, the purpose is to eliminate the above-mentioned drawbacks, that is, to increase the positioning accuracy (reduce the steady position deviation ε to zero) and shorten the positioning time. By selecting the gain curve according to the type and size of the friction and the rigidity of the system, the steady position deviation and the difference in the steady position deviation depending on the moving direction of the movable body can be made extremely small, improving positioning accuracy. I'm trying. The gain curve may be determined based on the following idea. In other words,■
When switching from speed control to position @v control, the positional deviation is large, so the overall loop gain is lowered, and thereafter, as the positional deviation becomes smaller over time, the loop gain is increased (third to fifth embodiments). Or, ■In order to bring the steady position deviation very close to zero, the smaller the position deviation, the higher the loop gain so that a position deviation voltage that generates enough motor torque to overcome the frictional force is output at any deviation position. (6th to 8th embodiments).

In FIG. 5, ce represents examples of gain characteristics selected in the third to eighth embodiments, C represents a linear change, d represents a logarithmic curve change, and C represents an n-dimensional curve change.

FIG. 7 shows a third embodiment of the invention. In the same figure,
3 to 5 and 7 to 11 are common to or correspond to each block shown with the same reference numerals in FIG. 1, 3 is a stop target position register, 4 is a position deviation counter, 5 is a D/A converter,
7 is a servo amplifier, 8 is a motor, 9 is a motor speed detector, 10 is a movable body, and 11 is a position detector.

Further, 32 is a maximum speed register, 33 is a selector for selecting either speed data or position deviation data, 34 is a multiplier, 35 is a D/A converter, and 36 is a data input to the D/A converter 35. The storage register 37 is a selector for selecting either speed data or gain data.

Reference numeral 38 is a speed curve table that stores speed data for creating speed curves, and stores not only the above-mentioned trapezoidal waveform curve but also various curves such as a verse sine wave, a cycloid wave, and an n-th order curve. ing.

In other words, when a 12-bit D/A converter 35 is used, the contents of the ROM as the speed curve table 38 represent the relationship between address n and data D (n) stored at that address n. For example, D (n) =
(2”-1) ・K (n)-2047-K <
n ) (0≦K(n)≦1). Here, K (n) is, in the case of O<n≦256, for example (1) Trapezoidal wave K (n>=n/256 (2) Parsing curve K (n) = (1/2) ・(1- cos (
nπ(3) Cycloid curve K (n) = (n/256) −(1/2 π)
・sin (2nπ/256) (4) Quintic curve K (n) = 6- (n/256)'15
-(n/256) +10・(n/256)'<5)
Exponential curve K (n) ==eXl) ((n/256)
−1). FIG. 8 shows data D(n) during acceleration and deceleration in the case of a trapezoidal wave in hexadecimal notation.

Returning to FIG. 7, 39 is a gain setting table (memory) that is a table for setting gains, and 40 is an oscillator that generates a reference clock for creating the acceleration/deceleration time of the movable body 10 and the timing for setting the gain. . The frequency of this oscillator 40 can be changed externally using a variable resistor (not shown) or the like. 41 is an up/down counter that counts time.

Next, the operation of the control system shown in FIG. 7 will be explained.

This control system is composed of, for example, a microprocessor or the like (not shown). Its operation is controlled by the III tll device. In this control system, when the travel distance of the movable body and the stop target position x 5, which is the sum of the current position (XO in FIG. 21) and the travel distance, are determined by the tJ tan process or by the input operation by the operator, Set the maximum speed vIIlaX in the maximum speed register 32 according to the moving distance, select the speed curve in the speed curve table 38, set the stop target position x 5 in the target position register 3, and set the target position location ( The gain curve of the gain setting table 39 is selected according to the absolute coordinates).

The gain table 39 is a one-dimensional table that uses the same value for variable gain data regardless of the absolute coordinates of the stop target position, and a two-dimensional table that uses variable gain data that changes depending on the location of the target position.
Although two dimensional tables are possible, a two-dimensional array is used here.

In the control system shown in FIG. 7, when the target position x 5 and the maximum speed V ma Set the counter 4 to obtain
1 is initialized, selector 33 and controller 31 are selected to the speed control side, and speed control is performed in the section a to d in FIG.

Oscillation here? The period of 41 seconds of 940 is the number of sample counts during acceleration or deceleration of the movable body 10, that is, the maximum count value output by the counter 41 is n, and the acceleration/deceleration time is TaC.
[Set by varying the frequency to a value found from 7ac-nxΔT [seconds] as second J. Further, the reference speed V is =K (n)·'J max.

After the oscillator 40 is operated, the counter 41 counts up at regular intervals, and normalized speed data K (n) is read from the speed curve table 38 in accordance with the count value n of the counter 41. This speed data K (n
) is temporarily stored in the register 36, converted into an analog signal by the D/A converter 35, and applied to the first multiplier 34 as the speed command voltage.
is input to the input terminal of

On the other hand, the maximum speed value VIIlax as digital data set in the maximum speed register 32 is converted into an analog voltage value by the D/A converter 5, and then input to the second voltage value of the multiplier 34.
is supplied to the input terminal of The multiplier 34 performs the calculation of the above formula, multiplies V max by K(n), and outputs the result as the reference speed (2) of the movable body. When the value n of the counter 41 reaches 256, K(256)=1. V=Vmax, and the speed of the movable body becomes constant at the maximum speed. When the deceleration start position at point C in FIG. 21 is reached, a deceleration speed curve can be obtained by using the counter 41 as a subtraction counter. Note that during this deceleration, by changing the set value of the oscillator 40, the acceleration time and deceleration time can be made different.

As a result of this speed control, when the movable body 10 reaches the vicinity of the target position, the selectors 33 and 37 are switched to the position control side, the variable gain time is set to the oscillator 40, and the counter 41 is initialized. Position control is performed using the variable gain mode, which is a feature of this embodiment.

In this position control, the ninth
Gain data from the gain setting table 39 as illustrated in the figure is read out at regular intervals and stored in the register 36. Tables 39x and 39V in FIG. 9 are for positioning the wafer WF, and are two-dimensional array tables corresponding to the location (x, y) of the target position.

Returning to FIG. 7, as shown in FIG.
/A converter 35 converts the voltage into analog.

As a result, the position error voltage is multiplied by the gain data. In other words, the loop gain of the control system can be varied according to the gain data. Note that the counter 41 does not count up after the final data of the gain table is read, and the register 36 holds the final gain data.

By doing this, it is possible to prevent the occurrence of vibration when switching from speed control to position control, and also to shorten positioning time, reduce steady position deviation, and reduce the difference in steady position deviation depending on the direction of movement. can be achieved.

Further, by generating the maximum speed setting and the speed curve separately, the speed curve data can be normalized, that is, similar waveforms can be unified as data, and the information m can be reduced. Therefore, the speed curve can be tabulated in the ROM, and any curve can be created. Further, the speed function generator can be separated into parts that generate acceleration/deceleration time, normalized speed curve data, and maximum speed, respectively, and the overall configuration of the device can be simplified.

Dish 4WIN FIG. 11 shows a control circuit according to a fourth embodiment of the present invention. In the circuit shown in FIG. 7 described above, the maximum speed register 32, speed curve table 38, oscillator 40, and counter 41 implement the same functions as the speed function generator 1 of the circuit shown in FIG. In the embodiment shown in FIG. 11, on the other hand, the speed control system is composed of the same speed function generator 1 as shown in FIG. , remove register 36 in FIG.
4 and the D/A converter 35, a multiplier type D/A converter 34' is connected between the D/A converter F[5 and the position control side contact of the analog switch 6, converter 3
4', the output of the D/A converter 5 is controlled in accordance with the gain data output from the gain table 39, and is supplied to the amplifier 7.

Fifth Embodiment FIG. 12 does not show an embodiment of a control circuit using a meter. In the same figure, 20 to 22 are common to or correspond to each block shown with the same reference numerals in FIG.
is a CPU, 21 is a memory, and 22 is a computer bus.

Further, 23' is a switching command flag for the speed command data latch 32' and the position deviation data counter 4'. In the memory 21, a speed curve table and a gain setting table are provided.

Here, the functions of blocks 37 to 41 shown in FIG. 7 are executed by a program using a computer.

Next, the operation of the control circuit shown in FIG. 12 will be explained with reference to the flowchart shown in FIG. 13.

When travel distance information is given to the CPU 20 in this control circuit, the maximum acceleration is determined by the motor torque, load torque, inertia force, etc., so the maximum speed is determined. In step SBI, the CP LJ 20 reads the deceleration time, deceleration section moving distance, and initial correction value corresponding to this maximum speed from the memory 21, and determines the deceleration start position and the switching position to the position control mode from these data.

Next, set these data in a predetermined area of the memory 21 (step 582), command the switching command flag 23', and switch the selector 6 so that the speed command latch 32' is connected to the D/A converter 5. . As a result, the speed control mode is entered, and speed control is performed in sections a to d in FIG. 21, which are acceleration, constant speed, and deceleration (step 883).

As a result of this speed control, when the final speed reaches the constant speed section d-e, the CP tJ 20 detects the control mode switching position based on the position deviation data of the position deviation counter 4' (step 5B4), and performs position control. When the mode switching position is reached, a command is given to the switching command flag 23' to switch to the position control mode.

After switching to position control mode, select the gain table (Fig. 14) according to the stop target position (step 585).
, the pointer for reading the gain table provided in the memory 21 is initialized, and the first gain data is read and set in the register 16 (step 5B6). As a result, the loop gain of the control circuit is determined by the multiplication type D/A converter 34', as described for the control system in FIG.
is varied according to the gain data. In the following step SB7, the end of the variable gain is checked, and if it has not ended, the pointer is incremented in step 888 to point to the next address in the gain table. Next, we checked the sample time and waited until the next gain data output timing arrived (step 889).
)11. Return to step SB6 and repeat the variable gain routine from step SB6 to step S89.

In this way, the gain is changed as shown in the gain curve of FIG.

Further, when it is determined in step 887 that the variable gain has ended, that is, when the pointer points to the last data in the gain table, the variable gain routine (step SB6
to 5B9), the process moves to the next positioning completion determination routine (step S B10), and when the positional deviation becomes less than or equal to a predetermined value, the positioning control operation is ended.

Note that this embodiment can be modified as appropriate.

For example, the selector 6, switching command flag 23', register 36, and multiplication type D/A converter 34' in FIG.
The speed command latch 32' is directly connected to the D/A converter 5, and during position control, the CPtJ20 reads the contents of the current position register in the position detector 11, that is, the current position, and issues commands according to the position deviation. If a command value obtained by multiplying the voltage by time-varying gain data is configured to be output to the speed command latch 32', the hardware components can be largely omitted.

Sixth Embodiment FIG. 15 shows a sixth embodiment of the present invention. Note that blocks common to or corresponding to those in each of the above-described embodiments are represented by the same reference numerals. That is, 3 is a stop target position register, 4 is a position deviation counter, 5 is a D/A converter, 7 is a servo amplifier, 8 is a motor, 9 is a Tanabata speed detector, 10 is a movable body, and 11 is a position detector. 32 is a maximum speed register, 33.
37 is a filleter, 34' is a multiplication type D/A converter, 36 is a register that stores data selected by the selector 37 between speed data and gain data, 38 is a memory that is a speed curve table, and 39 is a gain A memory is a table, 40 is an oscillator, and 41 is a counter.

Next, the operation of the control system shown in FIG. 15 will be explained.

In this system as well, as in the third embodiment (FIG. 7), once the travel distance of the movable body 10 and the stop target position, which is the sum of the current position and the travel distance, are determined, the maximum speed is determined according to the travel distance. Set the speed in the maximum speed register 32, select the speed curve in the speed curve table 38, set the target stop position in the target position register 3, and select the gain curve in the gain table 39 according to the target stop position. do.

As described above, the gain table 39 can be of two types: a one-dimensional table that uses the same variable gain data at all positions, and a two-dimensional table that changes depending on the absolute coordinates of the target position. FIG. 16 shows a two-dimensional array.

In the control system shown in FIG. 15, when the target position, maximum speed, etc. are set, and the setting of the oscillation frequency of the oscillator 40 is roughly completed, the counter 41 is initialized and the selector 33
Then, the selector 37 is selected to the speed control side to perform speed control in the section a to d in FIG. As a result of this speed control, when the movable body 10 reaches the vicinity of the target position, the selectors 33 and 37 are then switched to the position control side, and position control is performed in the variable gain mode, which is a feature of this embodiment.

In this position control, the position deviation, that is, the movable body 10
Gain data from the gain table 39 is selected based on the difference between the stop target position and the current position, and is stored in the register 36. The multiplier type D/A converter 34' divides the device deviation analog voltage formed by the D/A converter 5 according to the output value of the register 36 to change the gain of the control system. By doing this, it becomes possible to always set the loop gain KO of the control system to the optimum value according to the positional deviation, thereby reducing the steady-state positional deviation and also reducing the difference in the steady-state positional deviation depending on the direction of movement. I can do it. Also, the change in the position of the movable body after switching to position control is shown in Figure 6.
As shown by G, it converges to a steady position in a critical braking manner or in a slightly oscillatory manner. That is, positioning time is shortened.

FIG. 11 shows a seventh embodiment of the present invention. The circuit in the same figure differs from the one in FIG.
The digital parts of i and 11111 are separated and switched in the analog part.

m8'lst @ FIG. 18 shows an eighth embodiment of the present invention. The circuit shown in the figure is different from that shown in FIG. 12 (fifth embodiment) by changing the control program of the CPU 20, that is, the data stored in the memory 21.
' instead of the current position of the movable body 10, the current position counter 4
It is exactly the same except that `` is used.

Next, the operation of the control circuit shown in FIG. 18 will be explained with reference to the flowchart shown in FIG. 19.

In this ft1l 1111 circuit, the operations (steps SC1 to SC5C4) from performing speed control after the start of operation until the movable body 10 reaches the control mode switching position and switching the control mode to position control are the operations of the fifth embodiment (steps SC1 to SC5C4). Since this step is the same as steps 881 to 884 in FIG. 13, the explanation will be omitted.

After switching to position control in step SC4, the memory 21
A one-dimensional gain table corresponding to the target stop position is selected from among the two-dimensional gain tables (see FIG. 16). Then, in step SC5, the current position is read from the current position counter 4'', the difference between this current position and the stop target position, that is, the position deviation is calculated, and in step SC6, gain data is read from the gain table using the absolute value of the position deviation value. , is set in the register 36 (step SC7).

Next, in step S08, it is determined whether or not positioning has been completed. The end of positioning is determined by checking whether a certain period of time has elapsed since the start of position control and whether the position deviation value is within a standard value. If the position deviation value is not within the standard value within a certain period of time after the start of position control, it is determined in step SC9 that positioning has not been completed, and the above-mentioned position deviation meter and gain data are read out. , and positioning completion determination are repeated. On the other hand, if the positional deviation value is within the standard value in step SC8, it is determined in step SC9 that the positioning has been completed, and the positioning control operation is ended. As a result, the steady-state positional deviation becomes extremely small, and the difference in the steady-state positional deviation depending on the position or movement direction becomes small, and the positioning accuracy improves. If the above-mentioned certain period of time has elapsed without the positional deviation value falling within the standard value, it is determined that positioning is impossible, and error processing such as displaying a message to that effect is performed.

In the case of this example, especially ! 6. Since the loop gain at each point in time during control can always be set to the maximum value within the stable region or a value close to it, the steady position n deviation and the steady position deviation due to the moving direction of the movable body can be The difference in will decrease. In other words, positioning accuracy is improved. Furthermore, positioning time is shortened and reliability is also improved.

[Effects of the Invention] As described above, according to the present invention, it is possible to improve positioning accuracy and shorten positioning time.

[Brief explanation of drawings]

Fig. 1 is a block circuit diagram showing a first embodiment of the present invention, Fig. 2 is a block circuit diagram showing a second embodiment of the invention, and Fig. 3 is a block circuit diagram showing the second embodiment of the invention. FIG. 4 is a graph showing the stability limit of position deviation and gain in the positioning control device; FIG. 5 is a graph showing the relationship between time and gain in the circuit of FIG. 7; The figure is a response (position change) waveform diagram after switching to position control. Figure 7 is a block circuit diagram showing the third embodiment of the present invention. Figure 8 is the speed curve in the circuit of Figure 7. FIG. 9 is an explanatory diagram of the wafer positioning gain table in the circuit of FIG. 7. FIG. 10 is an explanatory diagram of the f! of the multiplier in the circuit of FIG. 7. 11 is a block circuit diagram showing a fourth embodiment of the present invention; FIG. 12 is a block circuit diagram showing a fifth embodiment of the present invention; FIG. 13 is a block circuit diagram showing a fifth embodiment of the present invention; A flowchart for explaining the operation of the fifth embodiment, FIG. 14 is an explanatory diagram of the gain table set in the memory in FIG. 12, and FIG. 15 shows a sixth embodiment of the present invention. Block circuit diagram; FIG. 16 is an explanatory diagram of a gain table for wafer positioning in the circuit of FIG. 15; FIG. 17 is a block circuit diagram showing a seventh embodiment of the present invention; FIG. FIG. 19 is a flowchart for explaining the operation of the eighth embodiment; FIG. 20 is a block diagram showing a conventional control circuit;
The figure is a diagram showing an example of a speed command curve. 1: Velocity function generator, 2.2': D/A converter, 3
:Stop target position register, 4.4': Position deviation counter, 4'': Current position counter, 5: D/A converter, 6:
Analog switch, 7: Amplifier, 8: Motor, 9: Speed detector, 10: Movable body, 11: Position detector, 13: Correction value register, 14: Deceleration end target position deviation register, 1
5: Differential device, 16: Deceleration end position deviation latch, 17: Correction value register, 18 2 control mode switching position deviation registers, 19: Comparator, 20 2 central processing unit (CPLI)
, 21: Memory, 23: Switching command device, 23': Switching command flag, 32 maximum speed register, 32': Speed command data latch, 33° 37: Selector, 34: Multiplier,
34' squaring type D/Δ converter, 35: D/A converter, 3
6: Register, 38: Speed curve table, 39 Gain table, 40: Oscillator, 41: Counter xct/14I tree ε Data stand '1151 t (-"Wine size Ikuro version
Figure 8 Figure 10 Proceedings 1 ■ Authoritative document (method) 5゜ March 27, 1986 6゜ Commissioner of the Patent Office Uga Michibe 7゜ 1,' Indication of the case 1986 Year Patent Application No. 111442, Title of Invention Positioning Control Device 3, Relationship with the Amendment Case Patent Applicant Location 3-307I, Shimomaruko, Ota-ku, Tokyo! No. 2 Name (100) Canon Co., Ltd. Representative Ryuzo Kaku 4, Agent 105 Address 2-8-1 Toranomon, Minato-ku, Tokyo Date of amendment order March 5, 1986 (Date of dispatch: 1988) .3.25) ``Drawings'' to be amended Details of the amendment The drawing with two drawing numbers (12, 18) will be deleted and the attached drawings 12 and 18 will be added.

Claims (1)

[Claims] 1. A movable body, a speed function generating means for generating a function representing a target speed when moving the movable body, a means for detecting the actual speed of the movable body, and a means for detecting the actual speed of the movable body. means for detecting a current position; means for detecting a deviation of the current position from a predetermined target position; when moving the movable body to the target position and positioning the movable body, first moving the movable body at the actual speed above the target position; A first servo control system is formed to move the movable body at a relatively high speed toward the target position by driving to match the target speed, and then the movable body is moved to zero the positional deviation of the current position. control mode switching means for forming a second servo control system that is driven to move to and stop the target position with relatively high positioning accuracy; gain function generating means for generating gain data as a function; and means connected to the second servo control system for calculating the product of the deviation of the current position and the gain data and supplying the product to the means for driving the movable body. 1. A positioning control device comprising: first multiplication means. 2. The speed function generating means includes a maximum speed data setting means, an acceleration/deceleration time setting means, a counter means for counting at a speed according to the set acceleration/deceleration time, and a standardization speed for the predetermined speed function. table means for storing standardized speed data as data and outputting standardized speed data corresponding to the count value output of the counter means; and second multiplication means for multiplying the standardized speed data output from the table means by the maximum speed data. 2. The positioning control device according to claim 1, wherein setting of the maximum speed and generation of the speed curve are separated. 3. The control mode switching means is configured to switch and connect a single multiplication means into the first and second servo control systems so that the control mode switching means doubles as the second and first multiplication means. The positioning control device according to scope 2.