JPH02123905A - Carrier control method - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a transportation control method in which a magnetically levitated bogie is driven by a linear motor or the like and travels on a track using inertia. , is formed from a secondary conductor fixed to the trolley, a linear motor fixed to the track, and a gap between them, while floating the transport trolley a certain distance using electromagnetic force with respect to the track. In a transportation control method in which the trolley is caused to travel along a track by the electromagnetic force of a magnetic circuit, a curved portion of the track has a rotation center at the center of curvature of the curve, and an attractive force is applied to the trolley at the curve. A suction means is provided that rotates in synchronization with the traveling speed of the cart while applying it in a non-contact manner, and the cart is configured to run while removing the centrifugal force applied to the cart at the curve with a phase film using the suction force. Keru.

(Industrial Application Field) The present invention relates to a transportation control method, and more particularly to a transportation control method in which a magnetic levitation cart is driven by a linear motor or the like and travels on a track by inertia.

In recent years, tolerances have become increasingly strict regarding dust generation from equipment in clean rooms during the semiconductor manufacturing process.
Therefore, as a transfer device used for transferring wafers between devices, the non-contact magnetic levitation method has no R, m.
That's why it's attracting attention.

This magnetic levitation transport device uses multiple linear motors (
The linear motor, the secondary conductor, and the gap between them form a magnetic circuit. The direction of the magnetic flux generated by the current flowing through the motor and the electromagnetic force generated in the direction perpendicular to the direction of the above-mentioned current provide thrust to drive the magnetically levitated trolley without contact), and the inertia drives the next linear motor. By repeatedly traveling to a certain location, the magnetically levitated vehicle is made to continuously travel on a track (rail).

When stopping a magnetically levitated cart, it is slowed down by applying thrust in the opposite direction to the direction in which it is moving, and then clamped with an electromagnet or the like. Magnetic levitation carts are equipped with batteries for levitation electromagnets, etc., and control device tongues, which makes the carts larger and larger, making it difficult to increase speed. ~ Power is required due to centrifugal force when rolling or turning a curve, which is a problem.

However, in recent years, especially in high-mix, low-volume production of half-and-half products, more and more speed is required to transport wafers between devices, and magnetically levitated carts are also required to run at high speeds.

(Prior Art) Fig. 6 shows the configuration of a conventional example and an explanatory diagram of a method of changing the direction of travel. left.

An electromagnet 3 and a position sensor +J4 are provided at the upper right side. A holding section 6 for holding a conveyed object 5 is formed at the lower part of the trolley 1.

On the other hand, 7 is a track (hereinafter referred to as a "rail"), for example, made of iron with a cross-sectional shape, and it runs f! has been established. In addition, a linear motor (
Primary conductors) 8 are scattered at predetermined intervals and fixed to the rail 7. The linear seventh 8 is arranged to face the secondary conductor 2 at a close distance.

The above-mentioned cart 1 and conveyed object 5 are suspended from the rail 7 by the attraction force of the electromagnet 3 to the rail 7, and
A servo circuit that controls the electromagnetic force (adsorption force) of the electromagnet 3 based on the position detection signal from the position sensor 4 allows the electromagnet 3 to be separated from the rail 7 by a small fixed distance without completely contacting it. It is like that.

On the other hand, a magnetic circuit is formed by the secondary conductor 2, the linear motor 8, and the gap between them, and when a current is passed through the linear motor 8, the generated electromagnetic force causes the trolley 1 to move as shown in Fig. 6 (Δ). A thrust is applied in the direction perpendicular to the plane of the paper. The direction of this thrust is determined by the current direction of the linear motor 8.

Due to this thrust, the trolley 1 runs inertia along the rail 7 in a non-contact manner while holding the transported object 5.

The linear motors 8 are scattered along the rail 7, and the distance between them is shorter than the distance traveled by the bogie 1 due to inertia, so the bogie 1 continuously travels along the rail 7. .

A conveyance device having such a configuration and operating principle is called a three-axis control type because it is controlled in three directions (axes): the vertical direction and the traveling direction. According to this three-axis control type transport device δ, when changing direction, the rail 7 is curved with curvature as shown in FIG. 6(B), and the cart 1 is moved along the kerf 9. This is done by avoiding running.

FIG. 7 shows an explanatory diagram of the configuration of a conventional example and a method of changing the direction of travel. In FIG. 7(A), reference numeral 11 denotes a trolley, and a secondary conductor 12 is fixed to the center inside thereof, and an electromagnet 13 for vertical direction and a position sensor 14 for vertical direction are provided at the lower part, A left-right direction electromagnet 15 and a left-right direction position sensor 16 are provided at the position.

Reference numeral 17 denotes a rail, and a rail near motor 18 is fixed to the upper center of the rail. A truck 11 is formed so as to surround most of the rails 17, and objects 19 are placed on the outer upper surface of the truck 11.

In the above configuration, the electromagnet 13 and the position sensor 14 cause the cart 11 to float above the rail 17 at a constant pressure [11], and the electromagnet 15 and the position sensor 16 cause the cart 11 to move left and right with respect to the rail 17. They are made to be spaced a certain distance MM in each direction.

Further, based on the same principle as the above-mentioned three-axis formation type conveyance device, the secondary conductor 12. The carriage 11 is moved by the linear motor 18 and the gap formed between them as shown in FIG. 7(A).
A thrust is applied in the direction perpendicular to the plane of the paper.

This conventional conveying device is also controlled in the left and right directions, so
It is called a 1Nl control type, and has the feature of being able to perform position control with higher precision than the 3-axis control type.

As a conveyance control method for changing the direction of this five-axis control type conveyance device, as shown in FIG. 7(B), a straight rail 17a
and 17b are arranged orthogonally to each other, a turntable 20 is installed at the intersection, and linear motors 18a and 18b are installed at predetermined neck positions. That is, when the cart 11 travels on the rail 17a without contact and reaches the turntable 20, the cart 11 is stopped there and 7. : Rotate the rear turntable 20 by 90' and turn the linear motor 18.
The bogie 11 is moved in the direction of the rail 17b by the thrust generated by b.

In this way, with the 5-axis control type, the left and right gaps are also strictly controlled, making it difficult to add curvature to the rail.
It uses a turntable system that rotates the 0 and connects it to the rail in a different direction.

[Problems that the invention attempts to solve]

However, in the conventional conveyance control method, 311
Both lil type and 5-axis control type conveyor devices can run at increased speed if the rails are straight, but when changing direction, the 3-axis control type does not have left and right gap control. , the rail can have a curvature, and as shown in Figure 6 (B), the convex part of the rail 7 exerts a force υj in the left and right direction, so the rail 7 runs along the curve 9. However, if the speed of approach to the car 19 is too fast, the centrifugal force will be greater than the above-mentioned regulating force, causing the bogie 1 to move in the 112 line, so the traveling speed will be increased above a certain level. I couldn't.

On the other hand, as shown in FIG. 7(B), the 5-axis control type direction change involves temporarily stopping the stand 1a11 on the turntable 20 and then rotating the turntable 2o, so it takes time to change the direction. As expected, the IC can only increase the running speed as a whole.

The present invention has been made in view of the above points, and an object of the present invention is to provide a transport control method that allows a magnetic levitation platform to travel at high speed even when the trajectory curves.

[Means to solve the problem]

FIG. 11 shows a diagram explaining the principle of the present invention. In the figure, reference numeral 21 denotes a bogie, which is levitated by electromagnetic force to a track (rail) 22 at a constant pressure, and a linear motor 23 installed on the rail 22 and a secondary conductor ( (not shown) and the gap between them, the electromagnetic force of the magnetic circuit forms the magnetic circuit along the rail 22.

In such a transportation control method for the truck 31, the present invention provides suction means for the truck 21 at the curve 24 of the rail 22. That is, this suction means is composed of an arm 26 having its rotation center at the center of curvature 25 of the cover 24, a fflla stone 27 provided at the tip of the arm 26, and a position sensor 28. The centrifugal force Jf is offset and removed by the suction force F.

(Function) As shown in FIG. 1, the bogie 21 is at the curve 24 at J3, where the radius of curvature of the curve 24 is r1, the speed of entry into the curve 24 is VO + the weight of the bogie 21 is m, and f=mvo2/r.
A centrifugal nozzle lf' that satisfies the following equation is received.

On the other hand, the arm 26 measures the speed V of the truck 21. When it rotates in synchronization with the electromagnet 27 provided at its tip,
The truck 21 is attracted toward the center of curvature of the curve 24. The electromagnet 27 has a structure in which a coil is wound around an Iaf body, for example, and the attraction force F can be controlled by controlling the current flowing through the coil.

This attractive force F is obtained by controlling the electromagnetic force of the electromagnet 27 based on the position detection signal of the position sensor 28 so that the distance between the position sensor 28 and the cart 21 is always a constant value.

Therefore, the suction force F balances the centrifugal force f.

Note that, ideally, the trolley running speed vo should be set so that f=F.
, and set the suction force 1: to a constant value accordingly. However, in reality, it is difficult to manufacture the curve 24 of the rail 22 with a constant curvature, and the curvature changes slightly. Based on the position detection signal of the sensor 28, the electromagnet 2
A servo is required to control the electromagnetic force of 7.

Further, the arm 26, together with the electromagnet 27, has a center of curvature 2.
5 as a fulcrum, it is configured to rotate while the above-mentioned suction force F is applied to the cart 21.

Note that the attraction force F by the electromagnet 27 causes the trolley 21 to curve 2.
It only needs to be done from the time you enter step 4 until the time you exit.

〔Example〕

FIG. 2 is a plan view of an embodiment of the present invention, and FIG. 3 is a cross-sectional view of an embodiment of the present invention. In both figures, the same components as those in FIG.

In FIGS. 2 and 3, the trolley 21 is made of plastic, for example, and is constructed to be lightweight, and a magnetic material 30 is fixed to the side surface of the kerf 24 on the side of the center of curvature.
5. A speed detection slit plate 31 having a large number of equally spaced slits is fixed to the opposite side.

The trolley 21 is a three-axis controlled magnetically levitated trolley, and as shown in FIG. and a position sensor (none of which are shown), and is suspended at a fixed distance of 1IIIil from, for example, an iron rail 22.

As shown in FIG. 2, a speed sensor 33 is provided at a predetermined position before the entrance of the curve 24.
Sensor 3 is installed at the side end of each rail 22 at the inlet and outlet of 4.
4 and 35 are provided.

Further, as shown in FIG. 2, the other end of the arm 26 is fixed to a rotating disk 36, and the center of rotation of the rotating disk 36 is made to coincide with the center of curvature of the car 124. rail 2
2, a plurality of linear motors such as linear motor 23°37 are fixed at regular intervals.

The speed sensor 32 and sensors 34 and 35 described above are each a photo sensor, each consisting of a light emitting diode and a phototransistor, so that the speed detection slit plate 31 just blocks the optical path from the light emitting diode to the phototransistor. pass. Reference numeral 38 shown in FIG. 3 is a light emitting diode (or) A transistor constituting the speed sensor 33, and the optical path is formed vertically across the slit plate 31 (other sensors 34, 35 (same as well).

However, while the speed sensor 33 outputs a speed detection signal with a frequency corresponding to the slit of the slit plate 31, the sensors 34 and 35 output a speed detection signal with a frequency corresponding to the slit of the slit plate 31, whereas the sensors 34 and 35 Upon entering,
The configuration is such that a detection signal is output at the time of exit from the calf 24).

That is, the sensors 34 and 35 are provided with a waveform shaping circuit on the output side of the phototransistor.

Further, as shown in FIG. 3, the rotation circle a336 is the motor 39
is directly connected to one of the rotating shafts. How to use the motor 39 is a rotating disk 4 with slits provided at equal intervals on the rotating shaft.
0 is fixed, and a photo sensor 41 is placed across this rotating disk 40. rotating disk 40 and fo]
~ The sensor 41 constitutes a well-known tachogenerator (or encoder), and the foot sensor 41 connects the motor 3.
A rotation detection signal having a level corresponding to the rotation speed of 9 is extracted.

The other end of the arm 26 is fixed to the rotating disk 36 and rotated integrally with the rotating disk 36 by the motor 39, so the rotation detection signal described above also corresponds to the rotational speed of the arm 36. In addition, in FIG. 3, 42 is a bearing.

This embodiment includes a radial force control unit that controls the attraction force of the electromagnet 27 so as to keep the distance between the position sensor 28 and the trolley 21 constant, and a motor 39 that controls the arm 26 so that δ1 is measured by the speed sensor 33. It has a rotation control section that rotates at a speed synchronized with the traveling speed of the bogie.Next, the configuration and operation of these control sections will be explained.

FIG. 4 shows a circuit system of one embodiment of the above-mentioned radial force control section, and the same components as in FIGS. 2 and 3 are given the same reference numerals. In FIG. 4, an appropriate reference voltage is input to a terminal 45 for setting the distance between the position sensor 28 and the truck 21 to a set value. This reference voltage is supplied to the feedback control circuit 46, where it is attenuated with the position detection voltage of the position sensor 28h1, etc., and converted into an error voltage. Supplied.

On the other hand, the flip-flop 49 is set to a set state by the output detection signal of the sensor 34, and is set to a reset state by the output detection signal of the sensor 35.

The Q output signal of the flip-flop 49 is applied to the switch 48 as a switching signal to the switch 48, and when it is at a high level (that is, the flip-flop 49
is in the set state), the switch 48 is turned on, and when it is at low level (that is, when the four Noritub flops are in the reset state), the switch 48 is turned off.

Therefore, the switch 48 is turned on only during the travel period when the trolley 21 travels from the entrance to the exit of the curve 24, and during this on period, the output error voltage of the amplifier 47 passes through the switch 48 and is supplied to the power amplifier 5o. After voltage-current conversion is performed here, a current of a level corresponding to the error voltage is caused to flow through the coil of the electromagnet 27.

As shown in FIGS. 2 and 3, the electromagnet 27 is located at a position facing away from the magnetic body 30, and the electromagnet 27 and the magnetic body 3
0, an attractive force F is generated between Ti
It changes depending on the current level flowing through the coil of the magnet 27.

If this attractive force F is larger than the centrifugal force f that the cart 21 receives while traveling on the curve 24, the cart 21 is displaced in the direction approaching the electromagnet 27, and on the other hand, if it is smaller than the centrifugal force f, the cart 1i21 moves away from the electromagnet 27. Displaced in the direction away from you.

The relative distance of the truck 21 to the position sensor 28 is measured by the position sensor 28, and a position detection voltage corresponding to the distance is fed back to the p circuit 46 again by feedback.

In this way, the centrifugal force F caused by the electromagnet 27 is
1 and the position sensor 28 is controlled to be maintained at a distance determined by the reference voltage applied to the terminal 4°5. Therefore, the centrifugal force f that the truck 21 receives is canceled out and removed by the above-mentioned suction force F.

Next, the configuration and operation of the rotation control section will be explained together with the circuit system shown in FIG. Figures 2 and 3 in Figure 14
Components that are the same as those in the figures are given the same reference numerals, and their explanations will be omitted. In FIG. 5, a speed detection signal with a frequency proportional to the traveling speed of the trolley 21, which is taken out from the speed sensor 33, is supplied to the F/V converter 52, where it is converted into a voltage at a level corresponding to the frequency. It is then supplied to the rear register 53 and held there. This is because the speed detection signal described above can only be obtained for a short period when the speed detection slit plate 31 passes the speed sensor 35, whereas rotation control requires at least a period from the entrance to the exit of the curve 24. be.

The speed detection voltage from the register 53 is supplied to the feedback control circuit 54, where it is combined with the speed detection voltage from the tachometer generator 59, which includes the rotating disk 40 and photosensor 41, and is converted into a speed error voltage.

This speed error voltage is determined by an appropriate gain G (when the rotational speed is
1) is applied by the amplifier 54 to the switch 56.

In use, reference numeral 57 denotes a flip-flop, which is set to a set state by a detection signal from the sensor 34 and set to a reset state by a detection signal from the sensor 35.

The Q output signal of this flip-flop 57 is applied as a switching signal to the switch 56, and similarly to the switch 48 shown in FIG. The switch 56 is turned on only during the period when the vehicle is traveling to the exit (at the time when the sensor 35 outputs the detection signal).

Therefore, only during the period when the bogie 21 is traveling on the curve 24, the speed error voltage from the amplifier 55 passes through the switch 56 and is supplied to the power amplifier 58, where it is converted into a current with a level corresponding to the voltage value. After that, it is supplied to the motor 39 to control its rotation.

The rotational speed of this motor 39 is detected by a tacho generator 59, and the rotational speed detection voltage is fed back to a feedback control circuit 54.

In this way, the truck 21 is configured to travel around the curve 24 at the same speed as the travel speed detected by the speed sensor 33.
The carriage 21 is attracted to the electromagnet 27 by the arm 261.
It is rotated together with the rotating disk 36 in synchronization with the rotation of the motor 39.

Furthermore, when the trolley 21 exits the curve 24, Sen+J
35, the register 53 is cleared and at the same time the flip 70 knob 57 is reset, the switch 56 is turned off, and the drive current of the motor 39 is cut off.

However, it goes without saying that the arm 26 must be returned to the position of the center 4 no 34 by some means before the cart 21 enters the calf 24 again.

According to this embodiment, 'Fi' installed outside the trolley 21
Since the attraction force of the magnet 27 is used, there is no power limit compared to the case where the power of the electric tat from the battery mounted on the cart 21 is used, so any amount of attraction force can be obtained.

Therefore, for example, when a 20Ky truck 21 passes a car 124 with a radius of curvature of 1 meter at a speed Vo of 5 m/sec, the centrifugal force applied to the truck 21 is actually 50ON9f, as can be seen from the notation formula, and this It is almost impossible to stop such a large centrifugal force by the force of an electromagnet generated by the battery mounted on the trolley 21, but according to this embodiment, a large attractive force corresponding to such a large centrifugal force can be prevented. can be generated.

This allows the carf 24 to also run the cart 21 at high speed.

〔Effect of the invention〕

As described above, according to the present invention, the centrifugal force that the magnetically levitated bogie receives when it passes through a curved portion of the track is offset and removed by suction force, and the above-mentioned magnetic levitation bogie is Since the above-mentioned trolley is run while applying suction force, even if the speed at which the trolley enters the curve is much faster than before, it can be maneuvered through the curve without deviating from the track. Therefore, it can be transported at high speed, greatly contributing to improvement of throughput, and has features such as being able to arrange the track with a high degree of freedom.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the principle of the present invention, Fig. 2 is a plan view of an embodiment of the invention, Fig. 3 is a sectional view of an embodiment of the invention, and Fig. 4 is a main part of the invention. FIG. 5 is a circuit diagram of an embodiment of another main part of the present invention; FIG. 6 is an explanatory diagram of the configuration and direction change method of a conventional example; FIG. It is an explanatory diagram of the structure of another conventional example and the method of changing the traveling direction. In the figure, 21 is a trolley, 22 is a track (rail), 23.37 is a linear motor, 24 is a curve, 25 is a center of curvature, 26 is an arm, 27 is an electromagnet, 28 is a position sensor, 30 is a magnetic body, 31 is a A slit plate for speed detection, 33 is a speed sensor, 34, 35 is a sensor, and 39 is a septa. Figure 2: The length of the flat hat with a large opening on the shelf. Diagram (B)

Claims (1)

[Claims] The transportation trolley (21
) while floating a certain distance, a magnetic circuit formed from the secondary conductor fixed to the trolley (21), the linear motor (23) fixed to the track (22), and the gap between them. In a conveyance control method in which the cart (21) is caused to travel along a track (22) by electromagnetic force, the center of rotation is set at the curve (24) of the track (22) at the center of curvature of the curve (24). Hold the curve (24
) is provided with suction means (26, 27, 28) that rotates in synchronization with the running speed of the trolley (21) while applying a suction force to the trolley (21) in a non-contact manner, and the curve (24) A transport control method characterized in that the cart (21) is caused to travel while the centrifugal force applied to the cart (21) is offset and removed by the suction force.