JPS61102105A - Levitating type conveyor - Google Patents

Abstract

PURPOSE:To alleviate the load of a power source by controlling an exciting current flowed to an electromagnet so that the normal value becomes zero irrespective of an external force applied to a conveying vehicle. CONSTITUTION:A conveying vehicle 22 levitates on a guide rail 22 by a magnetic attraction force produced between a magnetic supporting unit 23 placed on the vehicle 22 and a guide rail 21. A linear induction motor 25 is composed of a conductor plate 26 secured through a support plate 24 to the lower surface of the vehicle 22 and a stator 28 secured to a base. The unit 23 has electromagnetic coils 38, 39 and a permanent magnet 40. A controller controls to flow the exciting currents of the magnets 38, 39 in transient state on the basis of the outputs of a gap sensor 51 and a current detector or to become zero irrespective of the presence of the external force in the normal state.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a floating conveyance device for conveying small articles.
In particular, the present invention relates to a floating conveyance device that saves energy and space.

[Technical background of the invention and its problems]

2. Description of the Related Art In recent years, as part of office automation and factory automation, it has become common practice to move slips, documents, cash, materials, and the like between multiple locations within a building using conveyance devices.

The conveying device used for such applications is required to be capable of moving the conveyed object quickly and quietly. For this reason, in this type of transport device, the transport vehicle is supported on guide rails in a non-contact manner. Air or magnetism is generally used to support the transport vehicle in a non-contact manner. Among them, the method of magnetically supporting the conveyance vehicle can be said to be the most promising support method because it has excellent followability to guide rails and noise reduction effect.

By the way, conventional magnetic levitation type conveyance devices support the conveyance vehicle with electromagnets and stably support the conveyance vehicle by controlling the excitation current to the electromagnets. Therefore, the electromagnetic coil must be constantly energized,
It was not possible to avoid the disadvantage of high power consumption. Therefore, devices have been considered in which a permanent magnet provides most of the magnetic force required for the electromagnet to reduce power consumption. However, even in this case, if an external force is applied to the transport vehicle, for example when an object to be transported is loaded onto the transport vehicle, the electromagnet will constantly apply a force to push the transport vehicle back to its normal position. Since this is necessary, the increase in power consumption due to this is a problem. Furthermore, if there is a problem that the electric power applied to the electromagnet increases due to the application of external force to the transport vehicle, a large-capacity 'H source must be used as a power source to energize the electromagnet. However, there was a problem in that the overall size of the apparatus was increased.

[Purpose of the invention]

The present invention has been made in view of the above problems, and its purpose is to provide a floating transfer device that can save energy and save space by reducing power consumption. It is in.

[Summary of the invention]

In explaining the present invention, the basis for the control system in this apparatus will first be explained.

FIG. 4 is a diagram showing a typical configuration of the Flp gas support section in this device. That is, numeral 1 in the figure is a guide rail, and two electromagnets 2 and 3 are disposed opposite to each other with a gap P interposed therebetween at a portion facing the lower surface of this guide rail.

These two electromagnets 2 and 3 are constructed by winding a coil 6.7 around a yoke 4.5, respectively. and,
One end sides of both yokes 4 and 5 are magnetically coupled by a permanent magnet 8. The coils 6.7 are connected in series so as to generate magnetic fluxes in directions that are added to each other when the excitation current flows, and are further connected to the power source 9. These electromagnets 2, 3, permanent magnet 8 and tf power supply are:
It is attached to a transport vehicle (not shown) that runs on a guide rail 1.

In the magnetic support section configured in this manner, a magnetic circuit consisting of the h-shaped guide rail 1, the gap P1 yoke 4.5, and the permanent magnet 8 will be considered.

Note that, for the sake of simplicity, leakage magnetic flux in this magnetic circuit will be ignored. The magnetic resistance Rm of this magnetic circuit is Rm = "-(2z + ') ・==
−(i>μoS μS where μ0 is the vacuum permeability, S
are the cross-sectional area of the magnetic circuit, the length of the 2-digit air gap, the non-magnetic permeability of the area other than the air-gap portion of μ8, and t is the length of the magnetic circuit other than the air-gap portion.

Also, when the excitation current is not flowing through the coil 6.7, the empty 1
``The strength of the magnetic field generated in JP is Hms, the length of permanent magnet 8 is Am, and the total number of turns of coil 6.2 is N.

Assuming the excitation current to coil 6.2 is the total magnetic flux Φ generated in this magnetic circuit, Φ= (N I + Hm 1m)/Rm
--(2). Therefore, the total suction force F acting between the guide rail 1 and each yoke 4.5 is F = -s (Φ/S)2/μ.

It can be expressed as Here, when the equation of motion of the transport vehicle is derived with the direction indicated by 2 as the direction of gravity, it becomes as follows. In addition, here m is the load applied to the above-mentioned magnetic support part and the total quality of the magnetic support part: ? , g is the gravitational acceleration, and UITI is the magnitude of the external force applied to the transport vehicle.

On the other hand, the number Φ of magnetic flux interlinked with the coil 6.7 connected in series is Φ, = (NI +HmAm)N/Rm
... (5) Therefore, the voltage equation of the coil 6.7 is as follows, where R is the total resistance of the coil 6.7.

Here, Rm is a function of the gap length 2, as is clear from equation (1). Therefore, now, when ■ = 00, the suction force F
Assuming that the gap length when the and the gravity mg are in balance is zo, and the total magnetic resistance is Hm6, the minute amounts in equations (5) and (6) above are expressed as Δ2. As Δ°2・ΔI・z = z o +
It can be expressed as Δ2 blood i0+Δ0z t I=O+Δl.

Therefore, when the attraction force F in the above equation (3) is set to a steady point (zm), then the above equation (4) can be summarized as follows.

Z Similarly, the above equation (6) can be transformed into the stationary point (zeπ, I) = (Z(
When linearized in the vicinity of 110-0), it becomes. Above (7
), Equation (8) can be summarized into the following state equation.

However, s hgla&2B+&3**&3Smb31a
d21 are respectively. Here, for simplicity, the above equation (9) is written as: intersection=Ax+
It is expressed as BE+DUm −・−・αQ. The linear system expressed by this equation (9) is generally an unstable system where ° is unstable, but the state vector of the above equation (9) [Δ2. Δ
°z, Δl] and acceleration Δ”z, the applied voltage E can be determined in various ways, and the system can be stabilized by feedback control. For example, if C is an output matrix (in this case, the unit matrix), , the applied voltage is E = -!: Fl, F, , Fs) x Cxx = -F
Cx ・・・・・・aυ (However,
F, , F, , Fl is a feedback constant), then 0
Equation 1 becomes x = Ax - BFC
Um(s)) - (13. Here, 1 is the unit matrix, and xo is the initial value of X.

If the above equation 1 is confused and UIIll is the external force on the step, then the stability of −
--- Determinant of α det lΦ(s) This is guaranteed if the characteristic roots of l are all stored on the left half plane on the complex plane of S. In the case of equation (9), the characteristic equation of Φ(,) det lΦ
(s) l = O is s3+(bstFs ass)
s”+(azx+azs(bstFs as2))s+
azsbslFx azt(bsxFs-ass)=
O°°°゛°°α9. Therefore, Fl e F
By appropriately determining the value of 2 + Fl, detl
The arrangement of the characteristic root of Φ(s) I = O on the complex plane can be arbitrarily determined, and stabilization of the magnetic levitation system can be achieved. There is a hood like this on the magnetic support part...
Figure 5 shows a block diagram of the magnetic levitation system when control is applied. That is, the controlled object 11 is provided with a feedper and a re-in compensator 12;
In the figure, y represents Cx.

In such a magnetic levitation system, the external force U
With changes in bias voltage eo of n and applied voltage E,
Gap length deviation Δ2 and current deviation when the system is in a stable state. and Δ1. occurs.

The present invention converts the current steady-state deviation ΔI among the steady-state deviations expressed by the above equation (161,09) into the step-shaped external force UI.
This feature is characterized in that the magnetic support section is subjected to feedback control so that it becomes zero regardless of the presence or absence of 11.

That is, the present invention provides a guide rail in which at least a lower surface portion is formed of a ferromagnetic material, a carrier disposed on the guide rail so as to be able to run freely along the guide rail,
A plurality of 1!s attached to the transport vehicle so as to face the lower surface of the guide rail with a gap in between! a permanent magnet that is disposed in a magnetic circuit composed of a foundation stone, these electromagnets, the guide rail, and the air gap, is attached to the transport vehicle, and supplies a magnetomotive force necessary to levitate the transport vehicle; In the floating transport device, the floating transport device includes a sensor that is attached to the transport vehicle and detects a change in the magnetic circuit, and a control device that controls the value of current flowing through the electromagnet based on the output of the sensor, wherein the control device includes: The present invention is characterized in that the current flowing through the electromagnet is controlled so that the steady value of the excitation current flowing through the electromagnet becomes zero regardless of the presence or absence of an external force applied to the carrier vehicle.

The present invention employs, for example, the following control method in order to control the current steady state difference Δls in the calyx.

■External force Un is observed by a state observation device, and this observed value U
A method of giving m an appropriate r-in and feeding it back to the magnetic levitation system.

■A method in which the gear tooth length side difference IZs speed deviation Δ'2 and current deviation Δl are all given appropriate gains that are not zero at the same time, and each value is fed back to the magnetic levitation system via the filter that constitutes the primary system of 3. .

■ Integrate the current deviation Δ1 using an integral compensator, give the output value an appropriate gain, and send it to the magnetic levitation system as a feeder.
How to do it.

■Method of combining methods of ■, ■, or ■ above.

etc.

Here, method (2) will be explained as an example.

A block diagram of a magnetic levitation system using method (2) above is shown in FIG. That is, the above method uses the integral compensator 1 in addition to the feedback gain compensator 12 described above.
3 has been added. The gain of this integral compensator 13 is a matrix expressed by K=[O, O,], where 3 is the integral gain of the current deviation Δl. Therefore, the applied voltage E in this magnetic levitation system is E = -
It can be expressed as FXC-KCIx dt--Qv. Obtaining the state transition matrix Φ(8) in the same manner as above, Φ(11) = (sl1-sA+ 5BFc+BKc)
-' ・------(1!J. Transfer function G (sl is G(s)=sΦ(a) when external force Un is input and y expressed as y=Cx is output E That is, provided that Δ(s)=a'+(bstF3ass)s'+(bxl
Kx a2t+a23(b3+Fz-ass))a”+
(azsb3tFt-azt(b3xFs ass))
s-aztbstKs...
...It can be expressed as ■η. The characteristic machine of the transfer function G(s) is to convert Δ(s) expressed by the above equation (c) into Δ(
s) = O, Fl , F2 *
By appropriately determining F3 and K3, the magnetic levitation system shown in FIG. 6 can be stabilized.

Here, if the magnetic levitation system in the same figure is stable, then
The response of the deviation power supply Δl to the external force Un can be determined as follows using Laplace transform.

In this equation (A), since the external force Um is a step-like external force, if Fo is the outward magnitude, then Um (
s) = F o /a (!: fk'),
Therefore, it is clear that there actually exists a means for bringing the current steady-state deviation Δl close to zero, regardless of the presence or absence of the external force Un.

In order to detect each element of state hector

■An appropriate gap sensor, speed sensor, acceleration sensor, etc. integrates or differentiates one output signal using an integrator or differentiator as necessary, and calculates Δ2.
A method of detecting Δt' etc.

(2) Two elements of the state vector are detected by method (2) or (2), and the remaining one is observed by a state observation device, if necessary, together with the external force Um.

〔Effect of the invention〕

According to the present invention, the portion corresponding to the magnetic force required of the electromagnet is compensated by a permanent magnet, and the steady value of the excitation current flowing through the electromagnet is zero regardless of whether or not an external force is applied to the carrier. Therefore, current only flows transiently through the coil of the electromagnet when an external force is applied to the transport vehicle. Therefore, according to the present invention, the power consumed by the coil can be significantly reduced compared to the conventional method, and the burden on the power source can be reduced. In other words, it can greatly contribute to energy saving.

Furthermore, if the burden on the power source can be reduced in this way, a small-capacity power source installed in the transport vehicle will suffice. Therefore, it is possible to use a small and lightweight power supply.
It can also contribute to space saving of the device.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A floating conveyance apparatus according to an embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In FIG. 1, reference numeral 21 denotes a guide rail whose bottom surface is made of a ferromagnetic material.

A transport vehicle 22 is disposed on the guide rail 21 so as to be able to run freely along the guide rail 21 . Transport vehicle 22
is equipped with a magnetic support device 23, and the conveyance vehicle 22 is supported in a completely floating state on the guide rail 21 by the magnetic attraction force generated between the magnetic support device 23 and the guide rail 21. ing.

A conductor plate 26, which is a movable element of an IJ linear induction motor 25, is fixed to the lower surface of the transport vehicle 22 via a support plate 24. 25 stators 28 are fixed. Further, on the lower surface of the transport vehicle 22, there is a control device 29 that provides a control signal to the magnetic support device 23, and a power source 30 that supplies power to the control device 29 and the magnetic support device 23.
is installed.

The guide rail 2I includes angle-shaped members 21*, 21
b are laid out in parallel.

The transport vehicle 22 is composed of a flat container 22h in order to facilitate the transport of objects to be transported. Wheels 3 are attached to the lower surface of the transport vehicle 22 for supporting the transport vehicle 22 on the guide rail 21 in an emergency or the like.

The magnetic support device 23 has four magnetic support parts 33 disposed at positions facing the four corners of the transport vehicle 22, and each of the five magnetic support parts 33 is fixed to the transport vehicle. Four. The attachment of the □-shaped i is made up of a member 32. Further, each magnetic support portion 33 has two yokes 34 and 31 whose one end faces face the lower surface of the guide rail 21 with a slight gap therebetween; and these yokes 34 and 35.
Two electromagnets 3 consisting of coils 36 and 37 wound around
8.39, and a permanent magnet 40 interposed between the yoke 34 and 35.

Further, the control device 29 is configured as shown in FIG. In this figure, the arrows indicate the signal path, and the bar lines indicate the signal path. This control device 29 realizes control according to the method example shown in FIG.
Specifically, a sensor section 4 that is attached to the transport vehicle 22 and detects changes in the magnetic circuit formed by the magnetic support section 33
6, and the coil 3 based on the signal from the sensor section 46.
6.37, an arithmetic circuit 47 that calculates the power to be supplied to the
Based on the signal from this arithmetic circuit 47, the coil 36
．． 37, and a power amplifier 48 that supplies power to the power amplifier 37. The sensor section 46 preprocesses signals from the gap sensor 5 which is fixed to the yoke 34 or 35 and detects the gap length between each magnetic support section 33 and the guide rail 21, this gear, and the desensor 51. a modulation circuit 52 that detects the current value of the coil 36°370, and a current detector 53 that detects the current value of the coil 36°370.
It is made up of. On the one hand, the arithmetic port 47 introduces the signal from the gap sensor 51 via the modulation circuit 52, subtracts zo with the subtracter 54, and receives the output of this subtraction @S54 directly and also with the differentiator. 55 through feedback gain compensators 56 and 57, respectively.
On the other hand, the signal from the current detector 53 is guided to the feedback gain compensator 58, and after being introduced from the current detector 53 and compared with the O signal in the subtracter 59, the signal is sent to the integral compensator 60. Addition of the compensated signal and the three feedback gain compensators 56 to 58
The subtracter 62 compares the summed output from the subtracter 61 and outputs the difference to the power amplifier 48.

Note that the power supply 30 separately supplies power to the NOYAWARA/7'6 system, which requires relatively high power, and the arithmetic circuit system 1, which requires low power, so two power supply units 30*, 3 are used.
0b has become a reminder. These power supply units 30&,
30b also supplies power to each of the other magnetic support parts 33. The floating conveyance apparatus according to this embodiment configured in this manner operates as follows.

That is, the magnetic flux generated by the permanent magnet 40 in the magnetic support portion 33 passes through the yokes 34 and 35, the air gap, and the ferromagnetic portion of the guide rail 21 to form a magnetic circuit. This magnetic circuit maintains a predetermined gap length of 2° so as to have a magnetic attraction force that does not require any magnetic flux from the electromagnets 38 and 39 in a steady state where no external force is applied to the carrier 22. .

When an external force Un is applied in this state, the gap sensor 5
1 detects this and sends it to the arithmetic circuit 47 via the modulation circuit 52.
A detection signal is sent to the The arithmetic circuit 47 subtracts the gap length setting value s6 from the signal using the subtracter 54, and calculates the gap length deviation signal Δ. This gap length deviation signal Δ2 is
The signal is input to the feedback gain compensator 56, and after being converted into a speed deviation signal Δ2 by the differentiator 55, it is input to the feedback gain compensator 57. on the other hand,
The current deviation signal Δl is obtained from the measurement signal of the current detector 53, and is input to the FUTNO 4 and FUGIN compensator 58. The current deviation signal Δl is compared with the zero level by a subtractor 59, and the difference signal is used as an integral compensation signal Δl.
Man-powered. Then, it is added by an adder 61 and
The output signals of the two feedback gain compensators 56 to 58 and the signal of the integral compensator 60 are each given a predetermined gain and are fed to the 9W amplifier 48. In this way, the system is stabilized in a state where the current deviation Δl becomes zero.

In this way, according to this embodiment, the coils 36 and 37 have the following:
Current flows only in a transient state when an external force is applied to the transport vehicle 22 and a fluctuation occurs in the magnetic circuit, and in a steady state, the current is zero regardless of the presence or absence of an external force, which greatly reduces the burden on the power supply. It is possible to save energy and space.

Note that the present invention is not limited to the embodiments described above. For example, in the above embodiment, a method is adopted in which the current deviation Δ1 is integrated using an integral compensator, and an appropriate gain is given to this and the feed is controlled. You can do it like this. Further, as described above, a speed sensor or an acceleration sensor may be used instead of the gear, the sensor 51, and the current detector 53. FIG. 3 is a diagram showing an embodiment in which an acceleration sensor 65 and two integrators are used instead of the gap sensor 51. In this way, the gap length between the magnetic support part 33 and the f-id rail 21 may be detected by integrating the acceleration sensor twice. There is an advantage that the acceleration of the section 33 can be arbitrarily determined within a detectable range.

Furthermore, the present invention is not limited to one that performs analog control, but can also constitute a device that includes digital control elements.

As described above, the present invention can be implemented with various modifications without departing from the gist thereof.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a schematic configuration of a floating transfer device according to an embodiment of the present invention, and FIG. 1(a) is a perspective view, and FIG.
is a front view, FIG. 2(c) is a partially cutaway side view, FIG. 2 is a schematic diagram showing the control device of the device and its surrounding electrical configuration, and FIG. A block diagram showing a control device for a floating conveyance device according to an example, FIG. 4 is a diagram showing a magnetic support section which is a main part of the present invention, and FIG. 5 is a conventional control for stabilizing the magnetic support section. FIG. 6 is a block diagram showing the method of controlling the magnetic support section according to the present invention. 1.21...Guide rail, 2, 3, 38.39
...Electromagnet, 4,5,34.35...Yoke, 6,7
゜36.37...Coil, 8,40...Permanent magnet. 9.30...Power supply, 1no...Controlled object, 12, 5
6-58...Feedback gain compensator, 13゜6
0... Integral compensator, 22... Transport vehicle, 23... Magnetic support device, 25... Linear induction motor, 33...
Wheel, 46... Sensor section, 47... Arithmetic circuit, 55
...differentiator, 66.67...integrator.

Claims (5)

[Claims] (1) A guide rail having at least a lower surface portion formed of a ferromagnetic material, a carrier disposed on the guide rail so as to be able to run freely along the guide rail, and facing the lower surface of the guide rail with a gap in between. a plurality of electromagnets attached to the carrier, and a magnet arranged in a magnetic circuit composed of the electromagnets, the guide rail, and the air gap, and attached to the carrier to levitate the carrier. a permanent magnet that supplies the magnetomotive force necessary for In the floating conveyance device, the control device causes the excitation current to flow through the electromagnet so that the steady-state value of the excitation current flowing through the electromagnet becomes zero regardless of the presence or absence of an external force applied to the conveyance vehicle. A floating conveyance device that controls excitation current. (2) The control device includes a state observation device that observes the magnitude of the external force from the output value of the sensor unit, and a state observation device that provides a predetermined gain to the magnitude of the external force observed by the state observation device. 2. The floating conveyance device according to claim 1, further comprising means for feeding back the excitation current. (3) The control device applies a predetermined gain to each deviation of the gap length between the electromagnet and the guide rail, the speed of the conveyance vehicle in the gap length direction, and the excitation current of the electromagnet, all of which are not zero at the same time. 2. The floating conveyance device according to claim 1, further comprising means for feeding back the excitation current to the excitation current through a filter having a linear transfer function. (4) The control device includes an integral compensator that integrates the deviation of the excitation current with a predetermined gain, and means for feeding back the output value of the integral compensator to the excitation current. A floating conveyance device according to claim 1, characterized in that: (5) The sensor unit obtains a detected value of at least one of the gap length between the electromagnet and the guide rail, the speed of change in the gap length, the acceleration of change in the gap length, and the excitation current of the electromagnet. A floating conveyance device according to claim 1, wherein the floating conveyance device is a floating conveyance device.