JPS60134793A - Positioning controller - Google Patents

Abstract

PURPOSE:To perform the positioning control system of a linear motor having stable and high speed servo properties by switching the gain of an error amplifier between the case that a linear motor movable element is moved at the prescribed speed and the case that the element is moved at more than the prescribed speed. CONSTITUTION:A speed command signal in response to an error between a position command applied from a point P2 and a signal of a potentiometer 41 and a speed feedback signal are differentially compared at an addition point 28, and amplified by K1 and K2 times by error amplifiers 29, 30, respectively. The output of error amplifiers 29, 30 are fed through a switch 31 and a voltage/current converter 33 to a current controller 34. The switch 31 is shifted to the K1 side when the speed of the movable element of a linear motor is the prescribed speed or higher set by a level detector 32, and to the K2 side when the speed is the prescribed speed or lower set by the detector 32.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to highly accurate positioning control in a linear servo motor.

1. Structure of a conventional example and its problems FIG. 1 shows an example of the structure of a mechanical part of a conventional brushless linear servo motor. The stator 1 has a large number of tooth-shaped irregularities (concave and convex) made of magnetic material at a constant pitch in the longitudinal direction (movement direction of the mover).
These are hereinafter referred to as magnetic pole teeth) 2. 3 is a mover, and this mover 3 includes a permanent magnet 4 magnetized in both directions perpendicular to the moving direction of the mover, and two yokes 6 and 7 stacked to sandwich this from both sides. Three three-phase three-phase coils 8a, 8b, 8o are wound around a yoke, and three groups of magnetic pole teeth 5a, 5 are arranged on the stator facing surface of the yoke.
b.

5, a non-contact position detection sensor 9, and a means for maintaining a constant slight gap between the stator 1 and the movable element 3 and smoothly guiding the movable element. On the stator 1, a large number of knurled magnetic pole teeth 2 are provided in the longitudinal direction with a certain pinch, whereas the movable side yoke 6
, 7. There are a total of six groups of magnetic pole teeth, and the pitch of the magnetic pole teeth within the same group is equal to the pitch of the stator, but the pitches are so arranged that the phases of all the different groups are different. Specifically, the magnetic pole tooth groups 5a, 5b, and 5o of the yoke 7 have a phase difference of 120 degrees from each other, and the magnetic pole tooth group of the yoke 7 and the adjacent magnetic pole tooth group of the yoke 6 each have a phase difference of about 180 degrees. There is a difference. The coils 8a, 8b, and 8o are all wound around the yokes 6 and 7 to their full dimensions.

By sequentially applying current to the three three-phase coils, the movable element can be moved in the longitudinal direction on the stator.

In particular, if the coils are sequentially energized electronically according to the position information from the non-contact position detection sensor 9, smooth and continuous movement can be achieved.

FIG. 2 is a block diagram of a control circuit when positioning control is performed using the brushless linear DC servo motor. The position command given by the Pl of 1○ and the signal of the potentiometer 23 that recognizes the current position of the linear motor mover of 20 are compared at the addition point of 11, and the deviation is converted into digital and analog converters of 12. D/A conversion is performed using a device. The speed command signal that is the output thereof and the speed feedback signal that is the output of the speed detector that detects the speed of the 24 linear motor movers are compared for differences at 13 addition points. The output is then multiplied by 14 error amplifiers and converted into a current command by 15 voltage-current converters.

Reference numeral 16 denotes a current control circuit unit which sequentially switches the current flowing through the movable coils 19a, 19b, and 19° based on the signal from the non-contact position detection sensor 21, and operates the current detector 18 and the pulse width modulation circuit 17 ( (PWM circuit) to control the current and control the thrust of the linear motor. 2
2 is a stator of the linear motor. The linear motor moves until the position of the movable element becomes equal to the command position given to Pl of 10, and when the positioning is completed, the servo lock state is reached. However, in the linear servo motor with the above configuration, the pitch of the magnetic pole teeth is reduced, and the cogging force (pulsation of thrust due to attraction and repulsion of the magnetic circuit) occurs when the mover moves.
We have to try to reduce it. This is because the cogging force has an adverse effect on stable positioning with high accuracy. Therefore, the above-mentioned linear motor becomes a super multi-pole motor because the pitch of the magnetic pole teeth is small. When the movable element moves at high speed, the switching of the current flowing through the movable element coil also becomes faster, and the switching frequency of the switching current and the alternating frequency of the magnetic circuit become higher.As a result, the 31st pin 1, even when driven with a constant current, the linear motor thrust CF (N)) - Speed [IV (m/S)
] The characteristic is that as the speed increases, the thrust rapidly decreases. Note that 1 is constant at this time. This cause C1, [
) 1J The effects of iron loss due to an increase in the alternating frequency of the magnetic circuit and the influence of the coil electrical time constant due to an increase in the current switching frequency of the coil can be considered. From Fig. 3, the thrust of the current saw,
The thrust constant is a function of speed, and this characteristic is used to configure the positioning control circuit shown in Figure 2. In the case of configuring the positioning control circuit shown in Figure 2, the entire range including the area when the mover is moving and the servo lock state when the mover is stopped. Control is complicated to ensure system stability over a long period of time.

OBJECTS OF THE INVENTION The present invention improves the above-mentioned drawbacks and provides stable positioning control.

Structure of the Invention The present invention includes a position deviation detection unit that compares a target position command with a current position of a brushless linear DC servo motor mover;
A speed deviation detection unit that compares the output of the position deviation detection unit and a movable element speed voltage, an error amplification unit that amplifies the output of the speed deviation detection unit, and a brushless linear DC servo motor is driven by the output of the error amplification unit. , a drive circuit section, and the error amplification section operates when the linear motor movable element is stopped and the speed is below a predetermined speed, and when the movable element is accelerating, decelerating, or moving beyond a predetermined speed. Linear D is related to the positioning control device for brushless linear DC servo motors that can switch the gain in two stages.
When the C servo motor mover is stopped and the speed is less than the predetermined speed, the gain of the error amplification section is set to a low value, and when the servo motor mover is accelerating, decelerating, or moving beyond the predetermined speed, the error is increased. By setting the gain of the amplification section to be high, the linear DC servo motor exhibits stable servo performance with high coordination during acceleration and deceleration of the mover while it is still moving, and even when the mover is at rest or below a predetermined speed. It is possible to ensure stable positioning operation, and its practical value is high.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 4 is a block diagram of a control circuit in one embodiment of the present invention. The position command given by P2 of 25 and the signal of the potentiometer 41 for recognizing the current position of the linear motor movable element of 38 are compared at the addition point of 26, and the error is calculated by the digital/analog converter of 27. Perform D/A conversion. The speed command signal that is the output and the speed feedback signal that is the speed detector output that detects the speed of the 42 linear motor movers are 2
The difference is compared at 8 addition points, and the output is amplified by 1 and K2 times by a 29.3° error amplifier, respectively. K1,
The amplification factor of K2 is set to the relationship [K2<K1],
The outputs of K1 and K2 are connected to the inputs of the switches 31, respectively, and the switching of the switches 31 is controlled by the output of the level detector 32.

The output of the switch 31 is converted into a current command by a voltage-current converter 33 and sent to a current control circuit section 34. 37a
The current flowing through the mover coils of , 37b and 37o is 3
35 pulse width modulation circuits (PWM circuits) and 36
A current detector 34 and a current control circuit section 34 sequentially switch the current to control the thrust. 4o is a stator portion of the linear motor. Now, when a position command is given to P2 of 25, the linear motor mover starts accelerating. and 32
31 when the speed exceeds the predetermined speed set by the level detector.
The switch changes from 2 at 30 to 1 at 29. 2
Since 1 of 9 is set to a high amplification factor that is allowable for the system, the linear motor mover accelerates with full power and exhibits high-speed servo performance. When the target position is approached, the mover starts to decelerate at full power based on a predetermined deceleration curve.

Next, when the speed of the movable element is set by the level detector 32 and becomes lower than the predetermined speed, the switch 31 switches from 3o to 2.
The movable element stops at the target position and returns to the automatic state. 300 and 2 are set to a relatively low amplification factor that satisfies the servo rigidity (reaction force of the movable element against external force) required at the time of servo lock. In this way, when the mover speed exceeds a predetermined speed, the amplification factor of the system is increased to achieve high servo performance with full power, and when the mover is nearing the positioning completion area or after the positioning is completed, the amplification factor is reduced to the minimum necessary. By doing so, it is possible to achieve a stable positioning control system that is not affected by the change in the thrust constant with respect to the speed shown in FIG.

In this example, the amplification factor of the system was set to 1°K2 to 29.30.
Although the case where the system is configured with two stages has been described, it goes without saying that by increasing the number of switching stages as necessary, a more optimal agency control system can be constructed.

Note that it is necessary to use high-speed electronic switches such as analog switches for the 31 switches in the description of the embodiment.

Effects of the Invention As described above, the present invention includes a position deviation detection section that compares a target position command and the current position of the brushless linear DC servo motor mover, and a comparison between the output of the position deviation detection section and the mover speed voltage. a speed deviation detection section that amplifies the output of the speed deviation detection section, an error amplification section that amplifies the output of the speed deviation detection section, and a drive circuit section that drives a brushless linear DC servo motor using the output of the error amplification section, and when the linear motor mover is stopped or A brushless DC switch that switches the cane of the error amplifying section into two stages depending on when the speed is below a predetermined speed and when the mover is accelerating, decelerating, or moving beyond a predetermined speed.
Regarding the positioning control device for the linear servo motor, when the linear DC servo motor movable element is stopped or the speed is below a predetermined speed, the gain of the error amplification section is set to a low value,
This positioning control device sets the gain of the error amplifying section to a high value when the movable element is still accelerating or decelerating beyond a predetermined speed, and when the linear motor movable element speed exceeds a predetermined speed. By increasing the system amplification factor, achieving high-speed servo performance, and switching the system amplification factor to the minimum necessary value after the positioning is completed, even if the movable element is near the positioning completion area, it is possible to achieve high-speed servo performance. It is possible to achieve a positioning control system for a linear motor that is not affected by changes in the speed of the thrust constant and has stable and high-speed servo performance, and has great practical value.

[Brief explanation of the drawing]

Figure 1 shows a brushless linear DC servo motor machine +f
A perspective view of the fort SLS, Fig. 2 is a block diagram of a conventional linear DC servo motor control system, Fig. 3 is a thrust-speed characteristic diagram of the linear motor, and Fig. 4 is a control system in an embodiment of the present invention. FIG. 2 completed...D/A converter, 29, 3○...Error amplifier, 31...Switch, 32...Speed level detector, 33...Voltage-current converter, 38... ... Linear motor mover, 39 ... Position detection sensor for coil current switching, 4o ... Linear motor stator, 41
... Potentiometer, 42 ... Speed detector. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 No. 3 (Capital) F (N) No. 4 □□□

Claims (2)

[Claims] (1) a position deviation detection unit that compares the target position command and the current position of the brushless linear DC servo motor mover;
a speed deviation detection section that compares the output of the position deviation detection section and a movable element speed voltage; an error amplification section that amplifies the output of the speed deviation detection section; and a brushless linear DC servo motor based on the output of the error amplification section. When the LIJ near motor movable element is stopped or below a predetermined speed from the drive circuit section that drives it, and when the movable element is accelerating, decelerating, or moving beyond a predetermined speed, the error amplification section A positioning control device configured to switch gain in two stages. (2) When the IJ near DC servo motor mover is stopped and the speed is below the predetermined speed, set the gain of the error amplification section to a low value, and if the mover exceeds the predetermined speed and the speed is still 2. The positioning control device according to claim 1, wherein the gain of the error amplifying section is set to be high when the device is moving.