JPS61102106A - Levitating type conveyor - Google Patents

Abstract

PURPOSE:To stabilize the controlling performance of a magnetic levitation system by controlling an air gap length between an electromagnet and a guide rail always constant. 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 so that the output of a gap sensor 51 for detecting an air gap length between a magnetic support 33 and the guide rail 21 becomes constant. Thus, the controlling performance of a magnetic levitation system can be stabilized.

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 levitation type conveyance device that can stabilize the control of a magnetic levitation system.

[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.

Conveyance devices used for such applications are required to be able to move the conveyed object quickly and quietly. For this reason, in this scale transport device, the transport vehicle is supported on a guide rail in a non-contact manner. Air or transferred air is generally used to support the transport vehicle without contact. Among them, the method of magnetically supporting the conveyance vehicle has excellent followability to guide rails and noise reduction effect, and can be said to be the most promising support method.

By the way, conventional magnetic levitation type conveyance devices can be used when an external force is applied to the conveyance vehicle, such as when an object to be conveyed is loaded onto the conveyance vehicle or due to a centrifugal force load when the conveyance vehicle is traveling.
The excitation current of the magnet and the magnet 1''...fTfc steady displacement 1 occur''tc.

At this time, if the gap length displacement is too large, linear control of the magnetic levitation system becomes difficult, and a stable magnetic levitation state cannot be maintained.

[Purpose of the invention]

The present invention has been made in view of the above problems, and an object thereof is to provide a levitation type conveyance device that can achieve stable control of a magnetic levitation system.

[Summary of the invention]

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

FIG. 3 is a diagram showing a typical configuration of the magnetic support section in this device. In other words, 1 in the figure is the guide rail υ
, two electromagnets 2j3 are disposed opposite to each other with a gap P interposed therebetween in a portion facing the lower surface of the guide rail. These two electromagnets 2 and 3 are constructed by winding coils 6 and 7 around yokes 4 and 5, respectively. 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 that are added to each other when an excitation current flows, and are further connected to a power source 9. These electromagnets 2 and 3, permanent magnet 8, and power source 9 are attached to a transport vehicle (not shown) that runs on the guide rail 1.

In the magnetic support section configured as described above, a magnetic circuit consisting of the guide rail 1, the air gap P1 yoke 4, 5, and the permanent magnet 8 will now 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 can be expressed as follows. Here, μ0 is the vacuum permeability, S
is the cross-sectional area of the magnetic circuit, 2 is the air gap length, μ3 is the non-permeability of the area other than the air gap, and t is the length of the magnetic circuit other than the air gap.

In addition, the strength of the magnetic field generated in the air gap P when no excitation current flows through the coil 6.7 is expressed as 4m1, and the length of the permanent magnet 8 is 4m1.
When the total number of turns of the coil 6.7 is N and the excitation current to the coil 6.7 is I, the total magnetic flux Φ generated in this magnetic circuit is Φ= (N I +HTTI Am)/'Rm
--(2). Therefore, the front suction force F acting between the fidrail 1 and each yoke 4.5 can be expressed as follows. 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. Here, m is the load applied to the magnetic support part and the total mass of the magnetic support part, g is the gravitational acceleration, and Um is the magnitude of the external force applied to the carrier.
.

On the other hand, the number of magnetic fluxes ΦN interlinked with the coils 6.7 connected in series is Φ, = (NI+Hm4.)N/Rrtl-...-(5
), the voltage equation for coil 6.7 is
．． Letting the total resistance of 7 be R, ±=E-R0t.

Here, Rm is a function of the gap length, as is clear from equation (1). Therefore, when the attractive force F and the gravity mF are balanced at ■20, set the gear σ, the knob length by 20, and set the magnetic resistance Rmo, and linearize it using the above equations (5) and (6). do. In this case, the minute amounts of each of z, 4i', and Iri are set by Δ2. Δ°z, Δi, z”
It can be expressed as z o+Δ2 Aoi=0+Δ°2 I=O+Δi.

Therefore, the attraction force F in the above equation (5) is set at the steady point (z.

When linearized in the vicinity of breath, I) = (zo, O+0), it becomes t, and when , it becomes . Therefore, the above equation (+) can be summarized as follows.

Similarly, the above equation (6) can be changed to the stationary point (z, π, engineering) = (zo
,0. When linearized in the vicinity of O), it becomes. Above (7)
, (8) can be summarized into the following state equation.

However, s a21 * &23 r ass l a3
3 + b3J* d21 us, respectively. Here, for simplicity, the above equation (9) is written as: intersection=Ax+
It is expressed as BE+DUm -...nti. this(
The linear system expressed by equation (9) is generally an unstable system, but the state vector [Δ2. Δ'Z
IΔ1] and acceleration Δ“2, 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 E, E=-[Fl, F'2, F'3)xCxx=
-FCx...
.... αυ (where F11F'= , Fl is the feed constant), then formula 01 is: Cross=Ax-BFCx+DUm -...-
α2, and further, by Laplace transform of this 01 formula, ×
When calculating, x = L-'([ml-A+BPCI-'(x6+D
Um(s))) = (13. Note that here 1
is the identity matrix, and xo is the initial value of X.

In the above equation 03, if Um is the external force on ST and D, the stability of X is the state transition matrix Φ(8), that is, Φ(a) = (sl-A+8FC)-'
. . . It is guaranteed if the characteristic roots of the determinant detlΦ(8)1 of α are all on the left plane on the complex plane of S. In the case of equation (9), the characteristic equation d@tl of Φ(8)
Φ(s) l = O is s"+(bstFs-ass
)s”+(-a*t+axs(bstF2-ass))
s+axsbslF1-an(bsxFs ass)=
O=”<15. Therefore, F l 6 F
By appropriately determining the value of B tFg, detlΦ(
s) The arrangement of the characteristic root of l = 0 on the complex plane can be arbitrarily determined, and stabilization of the magnetic levitation system can be achieved.

FIG. 4 shows a block diagram of a magnetic levitation system in which such feedback control is applied to the magnetic support section. That is, the controlled object 11 includes a feeder and a gain compensator 12.
is added. Note that y in the figure represents Cx.

In such a magnetic levitation system, a step-like external force T
With changes in bias snow pressure eo of Jm and applied voltage E, gap length deviation Δ2 and current deviation Δ1 when the system is in a stable state
The steady-state deviation Δ2. is as shown below. and Δ13 occur.

In the present invention, among the steady deviations expressed by the above αG and αη equations, the gap length steady deviation Δ2. The present invention is characterized in that feedback control is applied to the magnetic support portion so that Um becomes zero regardless of the presence or absence of the step-like external force Um.

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 electromagnets attached to the carrier so as to face the lower surface of the guide rail with a gap in between; installed in
A permanent magnet that supplies the magnetomotive force necessary to levitate the carrier; a sensor that is attached to the carrier and detects changes in the magnetic circuit; and an excitation current that is applied to the electromagnet based on the output of this sensor. In the floating conveyance device, the control device maintains a gap length between the electromagnet and the guide rail regardless of the presence or absence of an external force applied to the conveyance vehicle. The present invention, which is characterized in that it controls the excitation current flowing through the electromagnet, is configured such that the steady deviation of the gap length Δ2. In order to control to zero, for example, the following control method is adopted.

■External force Um is observed by a state observation device, and this observed value U
How to feed rn to the magnetic levitation system by giving it an appropriate gain.

■Gear gear length deviation Δz1, speed deviation Δ°2, and current deviation Δ1 all have appropriate gains that are not zero at the same time, and feed each value to the magnetic levitation system via the filter that constitutes the primary system of S. Method.

■A method of integrating the air gap length difference Δ2 using an integral compensator, giving the output value an appropriate gain, and feeding it back to the magnetic levitation system.

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

etc.

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

The professional magnetic levitation system using the above method (■), the y-line diagram is shown in 5th.
As shown in the figure. That is, in the above method, a state observer 14 is added in addition to the feedper and r-in compensator 13 that are substantially similar to those described above. This state observation device 14 is, for example, a minimum-dimensional state observation device, and the state vector X is expressed as x/ == [:Δ2. Δ'z Hj I, Um]
`` '''·=· As αQ, the velocity Δ゛2 and the step-shaped external force Um are observed. Here, since the state vector is equation 08, (7), (
Equation 8) can be summarized into the following state equation.

x' = A'x' + B'g
−−−・−(lIHowever, in equation 0, the element directly detected by the sensor is Δ2
and Δi, the output equation of the system expressed by equation 01 is y'=C'x'...
... (a) However, . At this time, a minimum-dimensional state observer with Δ°2 and UIll as observed elements can be realized by the following equation.

However, αlltα21 here is a constant that can be appropriately determined so that the system expressed by the gradient equation is stable. In addition, the estimated value X includes Δ°2 to the observed element, the estimated speed value Δ2 of the external force Um, and the estimated external force value Un [Δ2. Δ2. The vectors are Δl and UmlT.

In Fig. 5, the applied voltage E is fed back to F/
] ~ Using Fl, E= CF'15F'21F'31F'4]X=
If F'X ・-・1241, the state transition matrix Φ of the system 8) is +1&(s)=(41-A'+B'F'
e(sl-K)-'Contains C'+B'F'f3C')-'
, =-@. Furthermore, if the initial value of the state vector of this magnetic levitation system is Xo', and the initial value of the formula is 2°BO, then the response of this system is X'(s)==v(s) (X 6 '4'F'C (
s I A) −' ZoBo ) ・・・=・・(
24.

Here, Φτ3) in formulas (c) and (c) above is, however, Δ(s): s3+(bsx Fs' ass ) s
2+(-azt +a2s (bo Fz'-a32
) ) a+azsbstFx'-azt(balF
3' ass) -QBJΔoB(s) =
s”+α1111+αHd21 ””°1
The elements that can be found in Kanji, excluding P141 and P34, are:
All can be described as polynomials of 3 with S as a factor.

Therefore, for each element of PH (1=1 to 3. By appropriately determining α21, Δ(lI)・Δ. If all the roots of B(s)=0 are arranged on the left half of the three planes, Δ2. Δ
'Z and Δ1 are guaranteed to converge to zero regardless of their initial values.

On the other hand, PI3 and P34 are respectively P 14 = dxs s3+dH(αxt+batF
s'-as3) s2+(α21 dzt +(bst
Fs'-a33) azt +b3t a23F'2
i dzt s+(αHdzx (bst Fs'
ass)-bsla23α21F4')b21・”
eAP34 “α32αzts”+(as2dztα1
1 d21bsxF+' dz+αo b31Fz'-
dzl(lxs bst F4') s” + (α3
2 aH2α21 d21αob3+F+'-dzt
bs+ Fz'(azx +dzxα2t))S+(ztbstdzt2Ft'-azt bsx dz!α
zx F4') --01), and these elements indicate that the external force Um causes steady deviations Δz/ and Δ1'3 in the system. Therefore, if F4' in equation (1) is determined as follows, the last term of the opening equation becomes zero, and P34
has a factor of 3, so other elements P3j (i=1 to 3, j
= 1 to 3), it means ensuring the pole at the origin of Φ'(8), so regardless of the presence or absence of the external force, there is no practical way to bring the steady gap length deviation Δz8 close to zero. exists in

In addition, in order to detect each element of the state vector, for example, ①Measure all the elements directly using an appropriate sensor, ②The output of one of the appropriate gears, pressure sensors, speed sensors, acceleration sensors, etc. The signal is partially differentiated using an integrator or differentiator as necessary to obtain Δ2. Δ
1, etc., ■Detecting the 2g element of the state vector using method ■ or ■, and observing the remaining one with a state observation device, if necessary, together with the external force Um. It will be done.

〔Effect of the invention〕

According to the present invention, by compensating for the part corresponding to the magnetic force required of the electromagnet with a permanent magnet and further controlling the excitation current flowing through the electromagnet, regardless of whether or not an external force is applied to the transport vehicle. Since the gap length between the electromagnet and the guide rail is always kept constant, the gap length does not change at all even when the transport vehicle is running or when the object to be transported is loaded, which makes controllability difficult. will not occur. Therefore, according to the present invention, it is possible to stabilize the control performance of the magnetic levitation system.

[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 freely run along the guide rail 21 . Transport vehicle 22
is equipped with a magnetic support device 23, and due to the magnetic attraction force generated between the magnetic support device 23 and the guide rail 21, the transport vehicle 22 is completely floated on the guide rail 21 and is supported in the next state. has been done.

A conductor plate 26, which is a movable element of a linear induction motor 25, is fixed to the lower surface of the carrier 22 via a support plate 24, and a pace portion 27 along the guide rail 21 is provided with a conductor plate 26, which is a movable element of a linear induction motor 25. A stator 28 is fixed. Further, the magnetic support device 23 is provided on the lower surface of the transport vehicle 22.
a control device 29 that gives a control signal to the control device 29;
A power source 30 that supplies power to the magnetic support device 23 and the magnetic support device 23 is mounted.

The guide rail 21 is an angular member j 1 a
It is constructed by laying e 2 l b in parallel.

The conveyance vehicle 22 is composed of a flat container 22 & in order to facilitate conveyance of objects to be conveyed. Wheels 31 are attached to the lower surface of the transport vehicle 22 to support the transport vehicle 22 on the guide rail 21 in an emergency or the like.

The magnetic support device 23 includes four magnetic support parts 33 arranged at positions facing the four corners of the transport vehicle 220, and four L-shaped magnetic support parts 33 for fixing these magnetic support parts 33 to the transport vehicle, respectively. The attachment is made up of a member 32. Further, each magnetic support portion 33 includes two yokes 34 and 35 whose one end face faces the lower surface of the guide rail 21 with a slight gap between them, and coils 36 and 37 wound around these yokes 34 and 35. The control device 29 is constructed as shown in FIG. 2. In this figure, arrows indicate signal paths and bar lines indicate power paths. 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
Coil 3 based on signals from sensor unit 46 of 6 and .
an arithmetic circuit 47 that calculates the power to be supplied to 6 and 37;
Based on the signal from this arithmetic circuit 47, the writing coil 3g
, 37. The sensor section 46 includes a 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, and receives signals from the gear and sensor 51. It is composed of a modulation circuit 52 for preprocessing and a current detector 53 for detecting the current value of the coils 36 and 37. The arithmetic circuit 42 receives the signal from the gap sensor 51 from the modulation circuit 52 at -1000.
After subtracting 1° by a subtractor 54, the output of this subtracter 54 is led to a state observer 56, and on the other hand, the signal from the current detector 53 is passed to the state observer 56. Furthermore, the signal outputted from the state observation device 56 and given a predetermined dyne by the feeder and fuguin compensator 57, and the signal outputted from the state observation device 56 and given a predetermined dyne by the feedback dyne compensator 58, 59.60, respectively. A signal having a predetermined gain is added by an adder 61, and the added output and a target value of deviation of zero are added by a subtracter 62.
The deviation is compared by the /4 power amplifier 48.
It is intended to be output to.

Note that the power supply 30 separately supplies power to the mother power amplifier system, which requires relatively large power, and the arithmetic circuit system, which requires small power, so it has two power supply units j (7a
v j (7b).These power supply units 30* and 30b each supply power to other magnetic support units 33. The transport device operates as follows.

That is, the magnetic flux created by the permanent magnet 40 in the magnetic support part 33 is distributed between the yoke 34, J5, the air gap, and the guide rail 2.
1 to form a magnetic circuit. This magnetic circuit has a predetermined air gap length z0 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.
is maintained.

When external force Um is applied in this state, 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 air gap length setting value 2° from the signal using the subtracter 54, and outputs the result to the state observers 5 and 6 as the air gap length deviation signal Δ2. On the other hand, the current deviation signal Δl is obtained from the measurement signal of the current detector 53, and is also input to the state observation device 56. Based on these signals, the state observer 56 calculates the estimated value ΔX of the state vector X using equations 1) and 2) described above. The calculation results are given predetermined gains by feedback gain compensators 57 to 60, respectively, and are fed to the power amplifier 48. The system is thus stabilized while maintaining a constant pore length.

In this way, according to this embodiment, the gap length between the electromagnets 38p39 and the guide rail is controlled to be constant regardless of whether or not the external force Um is applied. It is possible to eliminate the problem that the length deviation becomes too large and linear control becomes difficult. therefore,
The control performance of the magnetic levitation system can be stabilized.

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 external force Um is observed using the state observation device 56, and this observed value Um is given an appropriate gain and fed back to the knocker amplifier 48. You may also do so. Further, as described above, instead of the gap sensor 5 and the current detector 530, a speed sensor,
An acceleration sensor may also be used.@ Also, in the present invention, if necessary, the excitation current is controlled to be constant or zero in a predetermined region of the conveyance section, and the above-mentioned gap length is kept constant in other regions. Furthermore, the present invention is not limited to devices that perform analog control, but also devices that have digital control elements. can also be configured.

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 conveyance device according to an embodiment of the present invention, FIG. 1(a) is a perspective view, and FIG. 1(b) is a perspective view.
2 is a front view, FIG. 2 is a partially cutaway side view, FIG. 2 is a block diagram showing the electrical configuration of the control device and its surroundings, and FIG. 3 is the main part of the present invention. FIG. 4 is a block diagram showing a conventional control method for stabilizing the magnetic support portion; FIG. 5 is a block diagram showing a control method of the present invention for the magnetic support portion. . 1.21...Guide rail, 2 y 3 p 38
t39...electromagnet, 4,5,34,35...yoke,
67.36,37... Coil, 8,40... Permanent magnet, 9.30... Power supply, 11... Controlled object, 12
, 57-60... feedback gain compensator, 13
゜60... Integral compensator, 22... Transport vehicle, 23...
・Magnetic support device, 25...IJ Near induction motor, 3
DESCRIPTION OF SYMBOLS 1... Wheel, 33... Magnetic support part, 46... Sensor part, 47... Arithmetic circuit, 56... State observation device. Applicant's agent Patent attorney Takehiko Suzue Figure 3, Figure 4r! ! J

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 controls the control device so as to keep the gap length between the electromagnet and the guide rail constant regardless of the presence or absence of an external force applied to the conveyance vehicle. A floating conveyance device that controls an excitation current flowing through an electromagnet. (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 predetermined gain for the magnitude of the external force observed by the state observation device to excite the external force. 2. The floating conveyance device according to claim 1, further comprising means for feeding back the 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 gap length deviation with a predetermined gain, and means for feeding back the output value of the integral compensator to the excitation current. The 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.