JPH06319208A - Levitation type conveying apparatus - Google Patents

Abstract

PURPOSE:To provide a levitation type conveying apparatus, which not only reduces power consumption but also simplifies the entire apparatus and saves the space. CONSTITUTION:In a conveying vehicle 22, which is arranged along a guide rails 21 so that the vehicle can freely run, a plurality of magnetic supporting parts 33, which face the lower surfaces of the guide rails 21 through gaps and generate magnetic attraction force between the guide rails 21 and the vehicle when the supporting parts are magnetized, are mounted. In the magnetic circuit, which is constituted of the magnetic supporting parts 33, the guide rails and the gaps, permanent magnets 40, which supply the magnetomotive force required for levitating the conveying vehicle 22, are provided. A sensor part, which detects the change in the magnetic circuit and a control device having the control part, which reduces the steady state value of the exciting current flowing through the magnetic supporting parts 33 to zero regardless of the presence or absence of the external force acting on the conveying vehicle 22 based on the output of sensor part, are mounted on the conveying vehicle 22. A power supply, which supplies the power into these parts, is also mounted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a levitation type conveyance device for conveying small items, and more particularly to a levitation type conveyance device capable of saving energy and space.

[0002]

2. Description of the Related Art In recent years, as a part of office automation and factory automation, it has become widespread to move slips, documents, cash, materials and the like between a plurality of points in a building using a carrier device.

The transport device used for such an application is
It is required that the transported object can be moved quickly and quietly. Therefore, in this type of transfer device, the transfer vehicle is supported on the guide rails in a non-contact manner.

To support the transport vehicle in a non-contact manner, it is general to use pneumatic force or magnetic force. Among them, the method of supporting the carrier vehicle with magnetic force is
It has excellent noise reduction effect and can be said to be the most promising support means.

By the way, in the conventional levitation type carrier device in which a carrier vehicle is supported by magnetic force, the carrier vehicle is supported by an electromagnet, and the carrier current is stably supported by controlling an exciting current to the electromagnet. I am trying. Therefore, the coil of the electromagnet must be constantly energized, and the drawback of high power consumption cannot be avoided.

Therefore, there has been considered a device in which most of the magnetic force required for the electromagnet is applied by a permanent magnet to reduce the power consumption. However, even in this case, if an external force acts on the transport vehicle, for example, by mounting an object to be transported on the transport vehicle, it is necessary to constantly apply an electromagnet force to push the transport vehicle back to the steady position. Therefore, the increase in power consumption due to this is a problem. In addition, when the electric power applied to the electromagnet becomes large due to the external force acting on the transport vehicle in this way, a large-capacity power source must be used as a power source for activating the electromagnet, and as a result, the large size of the entire apparatus There was a problem of inviting.

[0007]

As described above, in the conventional levitation type carrier device in which the carrier vehicle is supported in a non-contact manner by using the magnetic force, much energy is consumed for levitating the carrier vehicle. There was a problem. Therefore, it is an object of the present invention to provide a levitation type transfer device which can reduce power consumption as well as simplify the entire device and save space.

[0008]

In order to achieve the above-mentioned object, a levitation type conveying apparatus according to the present invention is provided with a guide rail at least a part of which is made of a ferromagnetic material, and can freely travel along the guide rail. And a plurality of electromagnets attached to the carrier so as to face the guide rail via a gap, and arranged in a magnetic circuit composed of the electromagnets, the guide rails, and the gap. And a permanent magnet that is attached to the transport vehicle and supplies a magnetomotive force necessary to levitate the transport vehicle, a sensor unit that is attached to the transport vehicle and detects a change in the magnetic circuit, and this sensor. Control for controlling the exciting current flowing through the electromagnet so as to make the steady value of the exciting current flowing through the electromagnet zero regardless of the presence or absence of an external force acting on the transport vehicle based on the output of the section. A control device having a, and a power supply as a power supply source for the mounting has been guided vehicle mounting element to the transport vehicle.

[0009]

In explaining the present invention, the basis of the control method in this apparatus will be described first. FIG. 6 shows a typical configuration of the magnetic support portion in this device.

That is, in the figure, 1 is a guide rail,
Two electromagnets 2 and 3 are arranged so as to face each other with a gap P 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. Then, one ends of both yokes 4 and 5 are magnetically coupled by a permanent magnet 8. The coils 6 and 7 are connected in series so as to generate magnetic fluxes that are added to each other when an exciting current flows, and further connected to a power source 9.
The electromagnets 2, 3, the permanent magnet 8 and the power source 9 are attached to a transport vehicle (not shown) that travels along the guide rail 1. As can be seen from the above configuration, the yokes 4, 5 and the permanent magnet 8 form a U-shaped magnetic core with these, and are mounted so that both magnetic pole surfaces of the magnetic core face the lower surface of the guide rail 1. Will be.

In the magnetic support portion thus constructed, a magnetic circuit consisting of the guide rail 1, the air gap P, the yokes 4, 5, and the permanent magnet 8 will now be considered. For the sake of simplicity, the leakage magnetic flux in this magnetic circuit will be ignored. The magnetic resistance Rm of this magnetic circuit can be represented by Rm = {2z + (L / μ _S )} / μ ₀ S (1). Where μ ₀ is the magnetic permeability of vacuum, S
Is the cross-sectional area of the magnetic circuit, z is the air gap length, μ _S is the non-permeability other than the air gap portion, and L is the length of the magnetic circuit other than the air gap portion.

The strength of the magnetic field generated in the air gap P when the exciting current is not flowing through the coils 6 and 7 is Hm, and the permanent magnet 8 is
Is Lm, the total number of turns of the coils 6 and 7 is N, and the coil 6 is
If the exciting current to 7 is I, the total magnetic flux Φ generated in this magnetic circuit is Φ = (NI + HmLm) / Rm (2)

Therefore, the guide rail 1 and each yoke 4,
The total suction force F that acts between 5 and 5 can be expressed by F = −S (Φ / S) ² / μ ₀ = − (NI + HmLm) ² / (μ ₀ Rm ² S) (3). Here, when the equation of motion of the carrier is derived with the direction indicated by z as the direction of gravity,

[0014]

[Equation 1] Becomes Here, m is the load applied to the magnetic support and the total mass of the magnetic support, g is the gravitational acceleration, and Um is the magnitude of the external force applied to the transport vehicle.

On the other hand, since the number of magnetic fluxes Φ _N that the coils 6 and 7 connected in series interlink, is φ _N = (NI + HmLm) N / Rm (5), the voltage equation of the coils 6 and 7 is Coil 6,
Let R be the total resistance of 7.

[0016]

[Equation 2] Becomes

Here, Rm is a function of the air gap length z, as is apparent from the equation (1). Therefore, the gap length when the suction force F and the gravity mg balance when I = 0 is z
₀ and total magnetic resistance Rm ₀ , the above equations (5) and (6) are linearized in the vicinity of the air gap length z = z ₀ , velocity dz / dt = 0, and current I = 0. In this case, z, dz / dt and I are

[0018]

[Equation 3] Can be expressed as Therefore, if the attraction force F in the above equation (3) is linearized near the steady point (z, dz / dt, I) = (z ₀ , ₀ , 0),

[0019]

[Equation 4] Next to

[0020]

[Equation 5] If you put it

[0021]

[Equation 6] Becomes Therefore, the above equation (4) can be summarized as follows.

[0022]

[Equation 7] Similarly, the equation (6) is calculated by using the stationary point (z, dz / dt, I) = (z
_When linearized near ( ₀ , ₀ , 0),

[0023]

[Equation 8] Becomes The above equations (7) and (8) can be summarized in the following state equation.

[0024]

[Equation 9] However, a ₂₁ , a ₂₃ , a ₃₂ , a ₃₃ , b ₃₁ , and d ₂₁ are respectively

[0025]

[Equation 10] Is. Here, for simplicity, the above equation (9) is changed to

[0026]

[Equation 11] Represents. The linear system represented by equation (10) is generally an unstable system,

[0027]

[Equation 12] Stabilization can be achieved by obtaining the applied voltage E by various methods and applying feedback control to the system. For example, let C be an output matrix (in this case, an identity matrix), and apply voltage to

[0028]

[Equation 13] (However, if F ₁ , F ₂ , and F ₃ are feedback constants), equation (10) becomes

[0029]

[Equation 14] Then, when Laplace transform of this equation (10) is used to obtain x,

[0030]

[Equation 15] Becomes Here, l is an identity matrix and x ₀ is an initial value of x. In the above equation (13), if Um is a step-like external force, the stability of x is the state transition matrix Φ (s), that is,

[0031]

[Equation 16] It is guaranteed if the characteristic roots of the determinant det | Φ (s) of are all stored on the left half plane on the complex plane of s. In the case of equation (9), Φ
The characteristic equation det | Φ (s) | = 0 of (s) is

[0032]

[Equation 17] Becomes

Therefore, by appropriately determining the values of F ₁ , F ₂ and F ₃ , the arrangement of the characteristic root of det│Φ (s) │ = 0 on the complex plane can be arbitrarily determined, Stabilization of the magnetic levitation system can be achieved. FIG. 7 shows a block diagram of a magnetic levitation system in the case where such feedback control is applied to the magnetic support portion. That is, the feedback gain compensator 12 is added to the controlled object 11. In the figure, y represents Cx.

In such a magnetic levitation system, the air gap length deviation Δz and the current deviation Δi in the stable state of the system are shown below in accordance with changes in the step-like external force Um and the bias voltage e ₀ of the applied voltage E. Such stationary deviations Δz _S and Δi _S occur.

[0035]

[Equation 18]

In the device of the present invention, among the steady-state deviations represented by the above equations (16) and (17), the magnetic steady-state deviation Δi _S is set to be zero regardless of the presence or absence of the step-like external force Um. It is designed to give feedback control to the section.

According to the present invention, the steady current deviation Δi _S
In order to control 0 to zero, for example, the following control method is adopted. (A) A method of observing the external force Um by a state observing device, feeding this observed value Um with an appropriate gain and feeding it back to the magnetic levitation system, (B) Gap length deviation Δz, its time derivative, the speed deviation, and A method in which the current deviation Δi has an appropriate gain that is not all zero at the same time, and the respective values are fed back to the magnetic levitation system via a filter that constitutes the primary system of s, (C) the current deviation Δi is integrated by a compensator. It is a method of performing integration by using it, feeding the output value with an appropriate gain and feeding it back to the magnetic levitation system, a method of using (D) above (A), (B) or (C) together.

Here, the method (C) will be described as an example. A block diagram of a magnetic levitation system using the method (C) is shown in FIG. That is, in the above method, in addition to the feedback gain compensator 12 described above, the integral compensator 13 is added. The gain K of the integral compensator 13 is a matrix represented by K = [0,0, K ₃ ], and K ₃ is the integral gain of the current deviation Δi. Therefore, the applied voltage E in this magnetic levitation system is
Is

[0039]

[Formula 19] Can be expressed as Obtaining the state transition matrix Φ (s) in the same way as above,

[0040]

[Equation 20] Becomes With the external force Um as input, y represented by y = Cx
When the output is, the transfer function G (s) is

[0041]

[Equation 21] However, Δ (s) = s ⁴ + (b ₃₁ F ₃ −a ₃₃ ) s ³ + {b ₃₁ K ₃ −a ₂₁ + a ₂₃ (b ₃₁ F ₂ −a ₃₂ )} s ² + {a ₂₃ b ₃₁ F ₁ −a ₂₁ (b ₃₁ F ₃ −a ₃₃ )} s −a ₂₁ b ₃₁ K ₃ (21)

The characteristic root of the transfer function G (s) can be obtained by setting Δ (s) represented by the above equation (21) as Δ (s) = 0, and F ₁ , F ₂ , F ₃ , K By appropriately determining ₃ , the stabilization of the magnetic levitation system in FIG. 8 can be realized. here,
If the magnetic levitation system in the figure is stable, the external force Um
The response of the deviation current Δi to

[0043]

[Equation 22] Can be asked. In this equation (22), the external force U
Since m is a step-like external force, if F ₀ is the magnitude of the external force, then Um (s) = F ₀ / s, and Eq. (22) becomes

[0044]

[Equation 23]

After all, it is clear that there is actually a means for bringing the steady-state current deviation Δi _S close to zero regardless of the presence or absence of the external force Um. To detect each element of the state vector x, for example, (a) a method of directly measuring all the elements using an appropriate sensor, (b) an appropriate gap sensor, a speed sensor, an acceleration sensor, or the like Integrating or differentiating one output signal using an integrator or differentiator as needed to detect Δz or the time-differentiated value of it, etc. (c) Two elements of the state vector (a)
Alternatively, there may be mentioned a method of detecting by the method of (b) and observing the remaining one together with the external force Um by a state observing device if necessary.

Further, in the apparatus of the present invention, since the power source for supplying electric power to the elements mounted on the carrier vehicle is also mounted on the carrier vehicle, the complete non-contact levitation can be realized and this state can be maintained. Since the length of the wiring can be minimized and the loss in the wiring can be reduced, the load on the power supply can be further reduced.

[0047]

Embodiments will be described below with reference to the drawings. 1 to 3 show a levitation type carrier device according to an embodiment of the present invention. In these figures, number 21
Indicates a guide rail whose lower surface portion is formed of a ferromagnetic material. A transport vehicle 22 is arranged on the guide rail 21 so as to travel along the guide rail 21.

A magnetic support device 23 is mounted on the transport vehicle 22, and the magnetic support device 23 and the guide rail 21 are mounted.
The carrier 22 is supported in a state of being completely levitated with respect to the guide rail 21 by the magnetic attraction force generated between the carrier 22 and the guide rail 21.

A conductor plate 26, which is a movable element of the linear induction motor 25, is fixed to the lower surface of the transport vehicle 22 via a support plate 24, and the base portion 2 along the guide rail 21 is fixed.
A stator 28 of the linear induction motor 25 is fixed to 7. The magnetic support device 23 is provided on the lower surface of the transport vehicle 22.
Control device 29 for giving a control signal to
A power supply 30 for supplying electric power to the magnetic support device 23 is mounted.

The guide rail 21 is an angle member 21.
a and 21b are laid in parallel. Carrier 2
2 is a flat container 2 for facilitating the transportation of the transported object.
2a. Wheels 31 that support the transport vehicle 22 on the guide rails 21 in an emergency are attached to the lower surface thereof.

The magnetic support device 23 includes four magnetic support portions 33 arranged at positions facing the four corners of the transport vehicle 22.
And four L-shaped attachment members 32 for fixing the magnetic support portions 33 to the transport vehicle 22, respectively.

Each magnetic support portion 33 has two yokes 34, 35 whose one end faces the lower surface of the guide rail 21 with a slight gap, and coils 36, 37 wound around these yokes 34, 35. And two permanent magnets 40 inserted between the yokes 34 and 35. The coils 36 and 37 are connected in series so as to generate magnetic fluxes that are added to each other when an exciting current flows. As can be seen from the above configuration, yokes 34, 3
The 5 and the permanent magnet 40 form a U-shaped magnetic core with these, and are mounted on the transport vehicle 22 so that both magnetic pole surfaces of the magnetic core face the lower surface of the guide rail 21.

The controller 29 is constructed as shown in FIG. In this figure, arrows indicate signal paths and bar lines indicate power paths. This control device 29 is shown in FIG.
To realize the control by the method shown in FIG. 4, specifically, a sensor unit 46 that is attached to the transport vehicle 22 and detects a change in the magnetic circuit formed by the magnetic support unit 33.
Based on the signal from the sensor unit 46, the coils 36, 3
7 and a power amplifier 48 that supplies power to the coils 36 and 37 based on a signal from the calculation circuit 47.

The sensor portion 46 is the yoke 34 or 35.
Gap sensors 51 fixed to the magnetic support portions 33 and the guide rails 21 to detect gap lengths, and a modulation circuit 52 for pre-processing signals from the gap sensors 51.
And a current detector 53 for detecting the current value of the coils 36 and 37.

On the one hand, the arithmetic circuit 47 introduces the output signal of the gap sensor 51 through the modulation circuit 52, subtracts the gap length set value z ₀ by the subtractor 54, and outputs the output of this subtractor 54. Directly and differentiator 55
Through feedback gain compensators 56 and 5 respectively.
7 and on the other hand, the output signal of the current detector 53 is guided to the feedback gain compensator 58, and the output signal of the current detector 53 is compared with the 0 signal by the subtractor 59, and the output of this subtractor 59 is integrated. The signal compensated by the compensator 60 and the three feedback gain compensators 56 to 58.
A signal obtained by adding the output of 1 to the adder 61 is compared by a subtractor 62, and the deviation thereof is output to the power amplifier 48.

The power supply 30 has two power supply units 30 in order to separately supply power to a power amplifier system requiring a relatively large power and an arithmetic circuit system having a small power.
It is provided with a and 30b. These power supplies 3
0a and 30b also supply power to the other magnetic support portions 33, respectively.

The levitation type transporting apparatus according to this embodiment having the above-mentioned structure operates as follows. That is, in the magnetic support portion 33, the magnetic flux generated by the permanent magnet 40 is
A magnetic circuit is formed by passing through the ferromagnetic portions of the guide rails 21, 35, the air gaps. This magnetic circuit is used in the transport vehicle 2.
In a steady state in which no external force acts on 2, the electromagnets 38, 3
A predetermined air gap length z ₀ is maintained so as to have a magnetic attraction force that does not require the magnetic flux of 9 at all.

When the external force Um acts in this state, the gap sensor 51 detects this and sends a detection signal to the arithmetic circuit 47 via the modulation circuit 52. The arithmetic circuit 47 subtracts the air gap length setting value z ₀ from the signal by the subtractor 54 to calculate the air gap length deviation signal Δz. The gap length deviation signal Δz is input to the feedback gain compensator 56, converted into a speed deviation signal obtained by differentiating Δz with time by the differentiator 55, and then input to the feedback gain compensator 57.

On the other hand, the current deviation signal Δi is detected by the current detector 5
3 is obtained by the measurement signal and input to the feedback gain compensator 58. Further, the current deviation signal Δi is compared with the zero level by the subtractor 59, and the difference signal is input to the integral compensator 60. Then, the three feedback gain compensators 56 added by the adder 61
The output signal of 58 and the output signal of the integral compensator 60 are given a predetermined gain and fed back to the power amplifier 48.

Therefore, when an external force Um is applied, an exciting current having a magnitude and direction according to the external force Um flows through the coils 36, 37 of the electromagnets 38, 39, whereby the yokes 34, 35 and the guide rail 21 are connected. The magnetic attraction force between them is controlled to increase or decrease, and the time when the transport vehicle 22 moves to the floating position where the load of the transport vehicle 22 including the mounting element and the magnetic attraction force are balanced by the permanent magnet 40, that is, the current deviation. The system is stabilized when Δi becomes zero.

As described above, according to this embodiment, the coil 3
In 6, 37, current flows only in a transient state when an external force acts on the transport vehicle 22 and the magnetic circuit fluctuates, and in the steady state, the current is zero regardless of the presence or absence of the external force. It is possible to significantly reduce the load of and to save energy.

Since only the magnetic attraction force in the direction opposite to the gravity direction needs to be controlled by the electromagnets 38 and 39, the electromagnet 3
Since the guide rails 21 need only be provided above the parts 8 and 39, that is, the guide rails required for steady levitation and the guide rails required for convergence of the transient state can be shared, the overall structure can be simplified and the space can be saved. Can be planned.

The present invention is not limited to the above embodiment. For example, the above embodiment adopts a method of integrating the current deviation Δi by using an integral compensator and giving it an appropriate gain and feeding it back.
You may make it control by the other method mentioned above.

Further, as described above, the gap sensor 51
A speed sensor or an acceleration sensor may be used instead of the current detector 53. FIG. 5 shows an embodiment in which an acceleration sensor 65 and two integrators 66 and 67 are used instead of the gap sensor 51. In this way, the output of the acceleration sensor 65 may be integrated twice to detect the gap length between the magnetic support portion 33 and the guide rail 21. In this case, in particular, the set positions of the sensors are respectively set. There is an advantage that it can be arbitrarily determined within a range in which the acceleration of the magnetic support portion 33 can be detected.

Furthermore, the present invention is not limited to the one that performs analog type control, but it is also possible to construct an apparatus having a digital type control element. As described above, the present invention can be implemented with various modifications without departing from the gist thereof.

[0066]

According to the present invention, the portion corresponding to the magnetic force required for the electromagnet is compensated by the permanent magnet, and the steady value of the exciting current flowing through the electromagnet is adjusted by the external force acting on the carrier vehicle. Since it is set to zero regardless of the presence / absence, only a current transiently flows through the coil of the electromagnet when an external force acts on the carrier vehicle. Therefore, the power consumed by the coil can be significantly reduced as compared with the conventional case, the load on the power source can be reduced, and the energy saving can be greatly contributed.

Further, since the power source for supplying electric power to the elements mounted on the carrier vehicle is also mounted on the carrier vehicle, the complete non-contact floating can be realized, this state can be maintained, and the wiring length can be increased. Since the length can be minimized and the loss in wiring can be reduced, the burden on the power supply can be further reduced.

[Brief description of drawings]

FIG. 1 is a perspective view of a main part of a levitation type transport device according to an embodiment of the present invention.

FIG. 2 is a view of the main part viewed in the direction of the arrow along the line AA in FIG.

FIG. 3 is a side view showing the main part with a part thereof cut away.

FIG. 4 is a block diagram showing an electrical configuration of a control device of the floating transfer device and its periphery.

FIG. 5 is a block diagram showing a control device of a levitation type transport device according to another embodiment of the present invention.

FIG. 6 is a view showing a magnetic support portion which is a main part of the present invention.

FIG. 7 is a block diagram showing a conventional control method for stabilizing a magnetic support unit.

FIG. 8 is a block diagram showing a method of controlling a magnetic support unit used in the present invention.

[Explanation of symbols]

1, 21 ... Guide rails 2, 3, 3
8,39 ... Electromagnets 4,5,34,35 ... Yoke 6,7,3
6, 37 ... Coil 8, 40 ... Permanent magnet 9, 30 ... Power supply 11 ... Control object 12, 56-58 ... Feedback gain compensator 13, 60 ... Integral compensator 22 ... Transport vehicle 23 ... Magnetic support device 25 ... Linear induction Electric conductor 29 ... Control device 33 ... Magnetic support part 46 ... Sensor part 47 ... Arithmetic circuit 55 ... Differentiator 66, 67 ...
Integrator

Claims (6)

[Claims] 1. A guide rail at least a part of which is made of a ferromagnetic material, a carrier arranged so as to run along the guide rail, and the carrier so as to face the guide rail through a gap. A plurality of electromagnets mounted on the vehicle, and each magnetic circuit composed of the electromagnets, the guide rails, and the air gaps are arranged in the magnetic circuit and mounted on the transport vehicle, and are necessary for levitating the transport vehicle. A permanent magnet that supplies a magnetomotive force, a sensor unit that is attached to the transport vehicle and detects a change in the magnetic circuit, and the electromagnet regardless of the presence or absence of an external force that acts on the transport vehicle based on the output of the sensor unit. Control unit having a control unit for controlling the exciting current flowing through the electromagnet so that the steady-state value of the exciting current flowing through the carrier is zero, and the power supply to the carrier vehicle-mounted element mounted on the carrier vehicle. Source to become comprises a power source and serving as a floating type conveying apparatus according to claim. 2. The levitating transfer apparatus according to claim 1, wherein electric power from the power source is supplied to at least the electromagnet. 3. The state control device for observing the magnitude of the external force from the output value of the sensor section, and the control device for giving a predetermined gain to the magnitude of the external force observed by the state observing device. And a means for feeding back the exciting current to the exciting current. 4. The controller controls the deviations of the gap length between the electromagnet and the guide rail, the speed of the carrier in the gap length direction, and the exciting current of the electromagnet, all of which are not zero at the same time. 2. The levitation-type transfer apparatus according to claim 1, further comprising means for giving gains and feeding them back to the exciting current through a filter having a first-order transfer function. 5. The control device comprises an integral compensator for integrating the deviation of the exciting current with a predetermined gain, and means for feeding back the output value of the integral compensator to the exciting current. It is what is characterized by the above-mentioned.
The levitation type transport device described in. 6. The sensor unit detects at least one of a gap length between the electromagnet and the guide rail, a change speed of the gap length, a change acceleration of the gap length, and an exciting current of the electromagnet. The levitation type conveyance device according to claim 1, wherein the levitation type conveyance device is obtained.