JPS63311514A - Control system for position of linear pulse motor - Google Patents

Abstract

PURPOSE:To shift respective needles with holding the intervals of interneedle to constant and to shift the needles at a considerably high speed by feedback- controlling the positions of all the needles based on a position detection signal outputted last among plural position detection signals corresponding to respective needles. CONSTITUTION:Respective needles 2a and 2b have position sensors outputting the position detection signals which have detected the positions on a stator 1 as a digital quantity, and a control part 11 feedback-controlling the positions of all the needles 2a and 2b based on the position detection signal outputted last among plural position detection signals corresponding to respective needles 2a and 2b. With speed-controlling in accordance with the needle which shifts last when plural needles 2a and 2b are decelerated and accelerated, the intervals of interneedle can be held constant. Thus, respective needles 2a and 2b can efficiently be shifted at high speed while they adapt to the state of loads.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a position control system for a linear pulse motor equipped with a plurality of movers.

[Spine L1 Technology 1 Conventionally, a conveyance VC device that grips and moves a member has been provided, and this type of conveyor has two parts: a chuck device that grips the member to be conveyed, and a moving device that moves the chuck device. It is made up of devices. therefore,
There is a problem that two independent devices are required, making the configuration relatively complicated.In addition, the moving device must move a relatively heavy chuck device in addition to the components to be transported, so it cannot be moved at high speed. The problem is that it is not possible.

To solve these problems, a conveyance device using a linear pulse motor has been proposed.

This conveyance device has a stator formed in a straight line and a plurality of movable elements, and by holding a member between the plurality of movable elements, the chucking device and the moving device can be operated by the movable element itself. It is designed so that it can be used for both purposes. In this conveying device, in order to firmly grip and convey the member to be conveyed without dropping it on the way, it is necessary to hold the member between the movers while maintaining a predetermined holding force. In order to obtain this holding force, conventionally, a plurality of movers were moved at the same speed while keeping the distance between the movers constant.

However, in order to move the movers while keeping the distance constant, the moving speed of the movers had to be slow enough so that they would not step out even under the worst load conditions. .

On the other hand, even if load fluctuations occur, the linear pulse motor can be removed.
As a method for operating the movable element at high speed without causing the movable element to move, a method is known in which the position of the movable element is detected using a position detection sensor such as a back electromotive force sensor or an encoder, and the position of the movable element is controlled by closed loop control.

According to leap loop control, the position of the mover is detected while it is moving, and the movement timing is fed back to control the advance or delay of the excitation phase. ), open-loop system a<
Compared to the case shown by the broken line), acceleration and deceleration can be performed at a higher speed, and generally several times higher speed can be expected.

In this way, since closed-loop control allows acceleration and deceleration to be performed at a higher speed than open-loop control, it seems possible to solve the above-mentioned drawbacks of conveyance devices using linear pulse motors. However, when a member is transported using multiple movers, the load acting on each mover is different, so if each mover is individually controlled in a closed loop, it is difficult to maintain a constant distance between the movers. This causes the problem that the member to be transported may drop and cannot be transported.

Therefore, the method of individually controlling the movable elements in a closed loop cannot achieve the objective, and in the end, the members cannot be conveyed at high speed.

[Objective of the Invention 1 The present invention has been made in view of the above-mentioned points, and its object is to provide a plurality of movers, each mover adapting to the load state, and achieving high speed and An object of the present invention is to provide a position control system for a linear pulse smoke that moves efficiently.

[Disclosure of the Invention] (M) A position control method for a linear pulse motor according to the present invention controls the position of each movable element of a linear pulse motor including a plurality of movable elements that move along a linear stator. In the position control method, each movable element has a position sensor that outputs a position detection signal that detects the position on the stator as a digital quantity, and multiple position detection signals corresponding to each movable element are output. It has a control unit that performs feedback control of the positions of all movers based on the position detection signal that is outputted the slowest among the movers, and when accelerating or decelerating multiple movers, By adjusting the speed of each movable element, the distance between each movable element can be kept constant.

(Example) In this example, as shown in FIG. 1, one stator 1 formed linearly and two movers 2 at 2
b is installed, and each movable element 2 at Z b is driven in four phases. Each mover 2a,
2b incorporates back electromotive force detection coils (not shown) that detect the positions of the movers 2a and 2b on the stator 1 and output position detection signals.

The control unit that controls this linear pulse motor includes an excitation control unit 10, a position control unit 11, and a pair of units that receive a phase excitation command signal from the excitation control unit 10 to respectively excite the coils in each movable element 2at 2b. driver circuits 12a, 12
b, and a pair of back electromotive force detection circuits 13a, 13 that respectively receive outputs from the back electromotive force detection coils in each movable element 2 at 2 b and output position detection signals to the excitation control section 10.
It has b. The position control unit 11 sends a right movement command signal S to the excitation control unit 10 to move each movable element 2a*2b in the right direction (positive direction) in FIG.
. a synchronization selection signal S for selecting
is output. On the other hand, the excitation control section 10
1, a total of four signals are output: a right movement signal S41S5 indicating that each movable element 2 at 2 b has moved to the right, and a left movement signal indicating that it has moved to the left. The right movement command signal S,, S2 and the left movement command signal are simply the movable element 2a.

This shows the travel time of PIS 2 (a).
As shown in (b), when these signal levels become "H", the excitation control unit 10 outputs a phase excitation command signal to control the movable element 2av2b via the driver circuits 12a and 12b.
It drives the. On the other hand, when the movers 2 a and 2 b move, each time the mover 2 at 2 b advances one step, an output is obtained from the above-mentioned back electromotive force detection coil, and this is sent to the back electromotive force detection circuits 13 a and 13 b. The waveform is shaped and converted into position detection signals S, -S.

The position detection signals 86 to S are digital signals, and are composed of a pair of signals that are inverted every time the movers 2 a and 2 b advance two steps, and the phases of both signals are 90 degrees out of phase with each other. . Therefore, t52 diagram m~(i
), the combination of both signals causes “HL”
, 'HH', 'LH', and 'LL' are obtained, and the states change each time the movers 2a, 2b advance by one step. Based on the state changes of the position detection signals 86 to S, the excitation control unit 10 detects the movable element 2 as shown in FIGS. 2(d) and 2(e).
One pulse is output every time ms 2 b advances one step, and this pulse is used as the right movement signal S, , S,
Alternatively, it is input to the position control unit 11 as a leftward movement signal. In response to this signal, the position control unit 11 controls the movable elements 2 a,
2b determines how far it has advanced, and when it has moved to the preset desired position, it stops outputting the right movement command signal S2 or the left movement command signal, and moves the mover 28t2.
b is stopped.

By the way, in the excitation control gio, in the case of valve open M control (that is, as shown in FIG. 2(c), the synchronization selection signal S3
is "L"), the timing of outputting the phase excitation command signal for driving each movable element 2 at 2 b is determined by each position detection signal 86 to S corresponding to each movable element 2 a, 2 b.
Feedback control is performed independently of each other. Therefore, the speed of each mover 2a, 2b is individually adjusted according to the state of each load, etc.
2 The distance between b is not necessarily constant, that is,
If one of the movers 2b is pushing the member 3 to be conveyed, the load applied to the mover 2b will naturally be greater than that of the mover 2a, so as shown in the left half of FIG. (Fig. 2(d) and (e) clearly show this), the moving speed of the movable element 2b is slower than that of the movable element 2a.

On the other hand, in the case of synchronous control (that is, when the synchronous selection signal S is "H" as shown in FIG. 2(c)), the excitation control unit 10 A phase excitation signal is output based on the position detection signals 86 to 89 (that is, the position detection signal obtained from the movable element 2b in the above example), which is the slower one among them.

In this way, the mover 2a always moves slower.

Since the other movers 2a and 2b are aligned with the mover 2b, the distance between the two movers 2a and 26 is kept substantially constant.

The operation of transporting the member 3 by the transport device shown in FIG. 3 will be described below. First of all, set the valve open M control,
The member 3 is gripped by moving the movers 2a and 2b individually.

Once the member 3 is grasped, the control is switched to synchronous 'I11, and the movers 2a and 2b are moved with the member 3 sandwiched between the movers 2a and 2b.

Here, if it is assumed that the movement is to the right in FIG. 3, the following relationship holds true. That is, the movable element 2a has a thrust force F
a, Frictional force r ra Since the pressing force fga from the raS member 3 acts and the movable element 2a moves at an acceleration aa, the following equation holds true, assuming that am of the movable element 2a is ma.

F atma ・ 6 a-fga+ fra Similarly, the movable element 2b has a thrust force Fb, a friction force f rb,
A pressing force rgb acts on the member 3, and the quality mar
Since the movable element 2b moves at an acceleration αb while pushing the member 3 of s, the following equation holds true, assuming that the mass of the movable element 2b is mb.

Fb=mb-ab+fgb+frb+m5-alIHere, if the member 3 is moving while being held between the movers 2a and 2b, αa=Qb=αS (=α), and the frictional force fra = "rb (= fr), pressing force fga = rgb (= fg), fl Amount ma#
Since it is considered that mb (= m), it becomes Fb Fa#m5-G+2fg, and the thrust difference between Ryoumachi Moko 2a and 2b becomes a value that cannot be ignored. In other words, there is a difference in the thrust of Ryomachi Moko 2 a, 2 b, which means that Ryomachi Moko 2 a, 2 b
This means that there is a difference in the travel time per step. Here, since the value of Fb-Fa is positive, mover 2b requires a larger thrust. Therefore, if the outputs of both rotors 2a and 2b are about the same, mover 2b has a larger thrust force. Movement speed will be slow. Therefore,
In the case of synchronous control, the excitation timing of the next step is determined based on the position detection signal of the movable element 2b, so the speed of the movable element 2a is set in accordance with the speed of the movable element 2b, and eventually both rotators 2 It will move while keeping the distance between am 2 b constant. After moving to the target position in this way, return to asynchronous control and move the mover 2 at
2b are moved individually to separate the members 3.

In the above embodiment, a back electromotive force detection coil is used for position detection, but an encoder, an optical sensor that detects the magnetic pole teeth of the stator 1, etc. may also be used.
The explanation has been made assuming that there are two b's, but even if there are three or more, if synchronous control is performed using the slowest one as a reference,
It goes without saying that the technical idea of the present invention is applicable.

[Effect of the Invention J As described above, the present invention provides a position control method for controlling the position of each movable element of a linear pulse motor equipped with a plurality of movable elements that move along a straight stator. Each movable element has a position sensor that outputs a position detection signal that detects the position on the stator as a digital quantity. The controller has a control unit that performs feedback control of the positions of all movable elements based on the position of each movable element. It is possible to move the movable elements while keeping the distance between them constant, and since it is feedback control, it has the advantage that the movable elements can be moved at a considerably higher speed than open-loop control.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing one embodiment of the present invention, Fig. 2 is an explanatory diagram of the operation of the same, Fig. 3 is an explanatory diagram of the operation showing the force acting on the linear pulse motor used in the same, and Fig. 4 The figure is an operation explanatory diagram showing the difference between open-loop control and closed-loop control. 1 is a stator, 2 a, 2 b are movers, 3 is a member, 1
0 is an excitation control section, 11 is a position control section, 12as12b is a driver circuit, and 13a and 13b are back electromotive force detection circuits. Agent Patent attorney Ishi 1) Ai 73... Member Mei 2 Figure Ichii synchronization u! r, −1st order −1st period j扛−1111◆
@3 Figure 4, 5]'-Draw 71

Claims (1)

[Claims] (1) In a position control method that controls the position of each movable element of a linear pulse motor equipped with multiple movable elements that move along a linear stator, each movable element has a digital position on the stator. It has a position sensor that outputs a position detection signal detected as a quantity, and the position of all movers is feedback-controlled based on the position detection signal that is output the latest among the multiple position detection signals corresponding to each mover. 1. A position control method for a linear pulse motor, comprising a control section that controls the position of a linear pulse motor.