Abstract:
A guide system for an elevator, including a movable unit configured to move, such as,ascend and descend, along a guide rail, a beam projector configured to form an optical path of a light parallel to a moving direction of the movable unit, a position detector disposed on the optical path and configured to detect a position relationship between the optical path and the movable unit, and an actuator coupled to the movable unit and configured to change a position of the movable unit by a reaction force caused by a force operating on the guide rail on the basis of the output of the position detector.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims benefit of priority to Japanese Patent Application No. 11-192081 filed Jul. 6, 1999, the entire content of which is incorporated by reference herein. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an active guide system guiding a movable unit such as an elevator cage. 
     2. Description of the Background 
     In general, an elevator cage is hung by wire cables and is driven by a hoisting machine along guide rails vertically fixed in a hoistway. The elevator cage may shake due to load imbalance or passenger motion, since the cage is hung by wire cables. The shake is restrained by guiding the elevator cage along guide rails. 
     Guide systems that include wheels rolling on guide rails and suspensions, are usually used for guiding the elevator cage along the guide rails. However, unwanted noise and vibration caused by irregularities in the rail such as warps and joints, are transferred to passengers in the cage via the wheels, spoiling the comfortable ride. 
     In order to resolve the above problem, various alternative approaches have been proposed, which are disclosed in Japanese patent publication (Kokai) No. 51-116548, Japanese patent publication (Kokai) No. 6-336383, and Japanese patent publication (Kokai) No. 63-87482. These references disclose an elevator cage provided with electromagnets operating attractive forces on guide rails made of iron, whereby the cage may be guided without contact with the guide rails. 
     Japanese patent publication (Kokai) No. 63-87482 discloses a guide system capable of restraining the shake of the elevator cage caused by irregularities of the guide rails by controlling electromagnets so as to keep a constant distance from a vertical reference wire disposed to be adjacent to the guide rail, thereby providing a comfortable ride, and reducing a cost of the system by getting rid of an excessive requirement of accuracy for an installation of the guide rails. 
     However, in the present guide system for elevators as described above, there are some following problems. 
     The vertical reference wire may be easily set up in case of low-rise buildings having a relatively short length hoistway for an elevator, while it is difficult to fix the vertical reference wire in a hoistway so as to be adjacent to guide rails in case of high-rise buildings or super high-rise buildings recently built and appeared. Further, after fixing the vertical reference wire, the vertical reference wire itself often loses its linearity because of a deformation by an aged deterioration of buildings or an influence of thermal expansion. Therefore, it causes a problem that a lot of time and cost is needed for maintaining the fixed vertical reference wire. Furthermore, electromagnets may not be excited in advance against irregularities on the guide rails, since a vertical position of the cage cannot be detected by using the vertical reference wire. Accordingly, a vibration restraining control may not start to run until a position relationship with the vertical reference wire goes wrong due to the irregularities. As a result, a certain extent of shaking may not be restrained in view of the principle. Therefore, there is a limit to improving a comfortable ride in this system. 
     SUMMARY OF THE INVENTION 
     Accordingly, one object of this invention is to provide a guide system for an elevator, which improves a comfortable ride by effectively restraining the shake of an elevator cage. 
     Another object of the present invention is to provide a minimized and simplified guide system for an elevator. 
     The present invention provides a guide system for an elevator, including a movable unit configured to move along a guide rail, a beam projector configured to form an optical path of a light parallel to a moving direction of the movable unit, a position detector disposed on the optical path and configured to detect a position relationship between the optical path and the movable unit, and an actuator coupled to the movable unit and configured to change a position of the movable unit by a reaction force, caused by a force operating on the guide rail on the basis of the output of the position detector. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
     FIG. 1 is a perspective view of a guide system for an elevator cage of a first embodiment of the present invention; 
     FIG. 2 is a perspective view showing a relationship between a movable unit and guide rails; 
     FIG. 3 is a perspective view showing a structure of a guide unit of the guide system; 
     FIG. 4 is a plan view showing magnetic circuits of the guide unit; 
     FIG. 5 is a block diagram showing a circuit of a controller; 
     FIG. 6 is a block diagram showing a circuit of a controlling voltage calculator of the controller; 
     FIG. 7 is a block diagram showing a circuit of another controlling voltage calculator of the controller; 
     FIG. 8 is a perspective view showing a structure of a guide unit of a guide system of a second embodiment; 
     FIG. 9 is a plan view showing the guide unit of the second embodiment; 
     FIG. 10 is a block diagram showing a circuit of a controller of the second embodiment; 
     FIG. 11 is a block diagram showing a circuit of a speed calculator of the controller of the second embodiment; 
     FIG.  12 ( a ) is a side view showing a position detector of a third embodiment; 
     FIG.  12 ( b ) is a front view showing a position detector of a third embodiment; 
     FIG.  13 ( a ) is a side view showing a position detector of a fourth embodiment; 
     FIG.  13 ( b ) is a front view showing a position detector of a fourth embodiment; and 
     FIG. 14 is a side view showing a position detector of a fifth embodiment. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, the embodiments of the present invention are described below. 
     The present invention is hereinafter described in detail by way of illustrative embodiments. 
     FIGS. 1 through 4 show a guide system for an elevator cage of a first embodiment of the present invention. As shown in FIG. 1, guide rails  2  and  2 ′ made of ferromagnetic substance are disposed on the inside of a hoistway  1  by a conventional installation method. A movable unit  4  ascends and descends along the guide rails  2  and  2 ′ by using a conventional hoisting method (not shown), for example, winding wire cables  3 . The movable unit  4  includes four guide units  5   a ,  5   b ,  5   c ,  5   d  attached to the upper and lower corners thereof for guiding the movable unit  4  without contact with the guide rails  2  and  2 ′. 
     Laser radiators  6   a ,  6   b  and  6   c , which are fixed on the ceiling of the hoistway  1 , radiate lasers parallel to the guide rails  2  and  2 ′ respectively, and form optical paths  7   a ,  7   b  and  7   c  in the hoistway  1 . The laser radiators  6   a ,  6   b  and  6   c  may be, for example, laser oscillating tubes or a laser emitting semiconductor devices. 
     Two two-dimensional photodiodes  8   a  and  8   b  are attached at different vertical positions on the side of the movable unit  4  as position detectors. Further, a one-dimensional photodiode  8   c  is attached adjacent to the photodiode  8   b  at the same vertical level as the photodiode  8   d . These photodiodes  8   a ,  8   b  and  8   c  are disposed in the optical paths  7   a ,  7   b  and  7   c , respectively. The two-dimensional photodiodes  8   a  and  8   b  detect positions of the respective optical paths  7   a  and  7   b  in two-dimensions (x and y directions in FIG.  1 ). The one-dimensional photodiode  8   c  detects a position of the optical path  7   c  in one-dimension i(y direction in FIG.  1 ). 
     The optical paths  7   a  and  7   b  by the laser radiators  6   a  and  6   b  are formed in a verticals direction, and received on the two-dimensional photodiodes  8   a  and  8   b  fixed at different vertical positions relative to each other. Positions of the movable unit  4  with respect to the following five modes of motions of the movable unit  4  are detected on the basis of respective receiving positions of the optical paths  7   a  and  7   b  by a calculation described below. 
     I. y-mode(back and forth motion mode) representing a right and left motion along a y-coordinate on a center of the movable unit  4   
     II. x-mode(right and left motion mode) representing a right and left motion along a x-coordinate 
     III. θ-mode(roll mode) representing a rolling about the center of the movable unit  4   
     IV. ξ-mode(pitch mode) representing a pitching about the center of the movable unit  4   
     V. ψ-mode(yaw-mode) representing a yawing about the center of the movable unit  4   
     The laser radiator  6   c  forms the optical path  7   c  tilting slightly so that a receiving spot on a receiving plane of the photodiode  8   c  shifts in the y direction shown in FIG. 1 as the movable unit  4  moves from the lowest position to the highest position in the hoistway  1 . Since the photodiode  8   b  and the photodiode  8   c  are disposed at the same level and close to each other, a vertical position of the movable unit  4  in the hoistway is accurately detected by subtracting a value of an optical axis position on the photodiode  8   b  in the y-direction from a value of an Optical axis position on the photodiode  8   c  in the y-direction, even if a position of the movable unit  4  is changed. 
     The movable unit  4  includes an elevator cage  10  having supports  9   a ,  9   b  and  9   c  on the side surface thereof for the respective photodiodes  8   a ,  8   b  and  8   c , and guide units  5   a - 5   d . The guide units  5   a - 5   d  include a frame  11  having sufficient strength to maintain respective positions of the guide units  5   a - 5   d.    
     The guide units  5   a - 5   d  are respectively attached at the upper and lower corners of the frame  11  and face toward the guide rails  2  and  2 ′, respectively. As illustrated in detail in FIGS. 3 and 4, each of the guide units  5   a - 5   d  includes a base  12  made of non-magnetic substance such as Aluminum, Stainless Steel or Plastic, an x-direction gap sensor  13 , a y-direction gap sensor  14 , and a magnet unit  15   b . In FIGS. 3 and 4, only one guide unit  5   b  is illustrated, and other guide units  5   a ,  5   c  and  5   d  are the same structure as guide unit  5   b . A suffix “b” represents components of the guide unit  5   b.    
     The magnet unit  15   b  comprises a center core  16 , permanent magnets  17  and  17 ′, and electromagnets  18  and  18 ′. The same poles of the permanent magnets  17  and  17 ′ are facing each other putting the center core between the permanent magnets  17  and  17 ′, thereby forming an E-shape as a whole. The electromagnet  18  comprises an L-shaped core  19 , a coil  20  wound on the core  19 , and a core plate  21  attached to the top of the core  19 . Likewise, the electromagnet  18 ′ comprises an L-shaped core  19 ′, a coil  20 ′ wound on the core  19 ′, and a core plate  21 ′ attached to the top of the core  19 ′. As illustrated in detail in FIG. 3, solid lubricating materials  22  are disposed on the top portions of the center core  16  and the electromagnets  18  and  18 ′ so that the magnet unit  15   d  does not adsorb to the guide rail  2 ′ due to an attractive force caused by the permanent magnets  17  and  17 ′, when the electromagnets  18  and  18 ′ are not excited. For example, a material containing Teflon, black lead or molybdenum disulfide may be used for the solid lubricating materials  22 . 
     Each attractive force of the above-described guide units  5   a - 5   d  is controlled by a controller  30  shown in FIG. 5, whereby the cage  10  and the frame  11  are guided with no contact with the guide rails  2  and  2 ′. 
     The controller  30  is divided as shown in FIG. 1, but is functionally combined as a whole as shown in FIG.  5 . The following is an explanation of the controller  30 . In FIG. 5, arrows represent signal paths, and solid lines represent electric power lines around the coils  20   a ,  20 ′ a - 20   d ,  20 ′ d . In the following description, to simplify an explanation of the illustrated embodiment, suffixes “a”-“d” are respectively added to figures indicating the main components of the respective guide units  5   a - 5   d  in order to distinguish them. 
     The controller  30 , which is attached on the elevator cage  4 , comprises a sensor  31  detecting variations in magnetomotive forces or magnetic reluctances of magnetic circuits formed with the magnet units  15   a - 15   d , or in a movement of the movable unit  4 , a calculator  32  calculating voltages operating on the coils  20   a ,  20 ′ a - 20   d ,  20 ′ d  on the basis of signals from the sensor  31  in order for the movable unit  4  to be guided with no contact with the guide rails  2  and  2 ′, power amplifiers  33   a ,  33 ′ a - 33   d ,  33 ′ d  supplying an electric power to the coils  20   a ,  20 ′ a - 20   d ,  20 ′ d  on the basis of an output of the calculator  32 , whereby attractive forces in the x and y directions of the magnet units  15   a - 15   d  are individually controlled. 
     A power supply  34  supplies an electric power to the power amplifiers  33   a ,  33 ′ a - 33   d ,  33 ′ d  and also supplies an electric power to a constant voltage generator  35  supplying an electric power having a constant voltage to the calculator  32 , the x-direction gap sensors  13   a ,  13 ′ a - 13   d ,  13 ′ d  and the y-direction gap sensors  14   a ,  14 ′ a - 14   d ,  14 ′ d . The power supply  34  transforms an alternating current power, which is supplied from the outside of the hoistway  1  with a power line(not shown) for lighting or opening and closing doors, into an appropriate direct current power in order to supply the direct current power to the power amplifiers  33   a ,  33 ′ a - 33   d ,  33 ′ d.    
     The constant voltage generator  35  supplies an electric power with a constant voltage to the calculator  32  and the gap sensors  13  and  14 , even if a voltage of the power supply  34  varies due to an excessive current supply, whereby the calculator  32  and the gap sensors  13  and  14  may normally operate. 
     The sensor  31  comprises the x-direction gap sensors  13   a ,  13 ′ a - 13   d ,  13 ′ d , the y-direction gap sensors  14   a ,  14 ′ a - 14   d ,  14 ′ d , the photodiodes  8   a ,  8   b  and  8   c , and current detectors  36   a ,  36 ′ a - 36   d ,  36 ′ d  detecting current values of the coils  20   a ,  20 ′ a - 20   d ,  20 ′ d.    
     The calculator  32  controls, magnetic guide controls for the movable unit  4  in every motion coordinate system shown in FIG.  1 . The motion coordinate system includes a y-mode (back and forth motion mode) representing a right and left motion along a y-coordinate on a center of the movable unit  4 , an x-mode(right and left motion model) representing a right and left motion along a x-coordinate, a θ-mode(roll mode) representing a rolling about the center of the movable unit  4 , a ξ-mode(pitch mode) representing a pitching about the center of the movable unit  4 , a ψ-mode(yaw-mode) representing a yawing about the center of the movable unit  4 . In addition to the above modes, the calculator  32  also controls every attractive force of the magnet units  15   a - 15   d  operating on the guide rails, a torsion torque around the y-coordinate caused by the magnet units  15   a - 15   d , operating on the frame  11 , and a torque straining the frame  11  symmetrically, caused by rolling torques that a pair of magnet units  15   a  and  15   d , and a pair of magnet units  15   b  and  15   c  operate on the frame  11 . In brief, the calculator  32  additionally controls a ζmode (attractive mode), a δ-mode (torsion mode) and a γ-mode (strain mode). Accordingly, the, calculator  32  controls in a way that exciting currents of coils  20  converge zero in the above-described eight modes, which is a so-called zero power control, in order to keep the movable unit  4  steady by only attractive forces of the permanent magnets  17  and  17 ′ irrespective of a weight of a load. 
     This control method is disclosed in detail in Japanese Patent Publication(Kokai) No. 6-178409, the subject matter of which is incorporated herein by reference. A guide control of this embodiment is executed on the basis of the position data of the optical paths  7   a ,  7   b  and  7   c . The following describes the guide control executed in this embodiment. 
     To simplify the explanation, it is assumed that a center of the movable unit  4  is on a vertical line crossing a diagonal intersection point of the center points of the magnet units  15   a - 15   d  disposed on four corners of the movable unit  4 . The center is regarded as the origin of respective x, y and z coordinate axes. If a motion equation in every mode of magnetic levitation control system with respect to a motion of the movable unit  4 , and voltage equations of exciting voltages applying to the electromagnets  18  and  18 ′ of the magnet units  15   a    15   d  are linearized around a steady point, the following formulas 1 through 5 are obtained. 
     Formula 1 is as follows:                          {               M                 Δ                   y   ab   ″       =       4          ∂     F   ya         ∂     y   a            Δ                 y     +     4          ∂     F   ya         ∂     i   a1            Δ                   i   y       +     U   y                                    (       L   x0     -     M   x0       )        Δ                   i   y   ′       =         -   N            ∂     Φ   b1         ∂     y   a            Δ                   y   ′       -     R                 Δ                   i   y       +     e   y                             Δ                 y     =         Δ                   y   a       +     Δ                   y   b       +     Δ                   y   c       +     Δ                   y   d         4                         Δ                   i   y       =         Δ                   i   ya       +     Δ                   i   yb       +     Δ                   i   yc       +     Δ                   i     y                 d           4                         e   y     =         Δ                   e   ya       +     Δ                   e   yb       +     Δ                   e   yc       +     Δ                   e     y                 d           4                                  
     Formula 2 is a follows:                          {               M                 Δ                   x   ab   ″       =       4          ∂     F   xb         ∂     x   b            Δ                 x     +     4          ∂     F   xb         ∂     i   b1            Δ                   i   x       +     U   x                                    (       L   x0     +     M   x0       )        Δ                   i   x   ′       =         -   N            ∂     Φ   b1         ∂     x   b            Δ                   x   ′       -     R                 Δ                   i   x       +     e   x                             Δ                 x     =           -   Δ                     x   a       +     Δ                   x   b       +     Δ                   x   c       -     Δ                   x   d         4                         Δ                   i   x       =           -   Δ                     i   xa       +     Δ                   i   xb       +     Δ                   i   xc       -     Δ                   i     x                 d           4                         e   x     =           -   Δ                     e   xa       +     Δ                   e   xb       +     Δ                   e   xc       -     Δ                   e     x                 d           4                                  
     Formula 3 is as follows:                          {                 I   θ                   Δ                   θ   ab   ″       =         l   θ   2            ∂     F   xb         ∂     x   b            Δ                 θ     +       l   θ   2            ∂     F   xb         ∂     i   b1            Δ                   i   θ       +     T   θ                                    (       L   x0     +     M   x0       )        Δ                   i   θ   ′       =         -   N            ∂     Φ   b1         ∂     x   b            Δ                   θ   ′       -     R                 Δ                   i   θ       +     e   θ                             Δ                 θ     =           -   Δ                     x   a       +     Δ                   x   b       -     Δ                   x   c       +     Δ                   x   d           2        l   θ                             Δ                   i   θ       =           -   Δ                     i   xa       +     Δ                   i   xb       -     Δ                   i   xc       +     Δ                   i     x                 d             2        l   θ                             e   θ     =           -   Δ                     e   xa       +     Δ                   e   xb       -     Δ                   e   xc       +     Δ                   e     x                 d             2        l   θ                                      
     Formula 4 is as follows:                          {                 I   ξ                   Δ                   ξ   ab   ″       =         l   θ   2            ∂     F   yb         ∂     y   b            Δ                 ξ     +       l   θ   2            ∂     F   yb         ∂     i   b1            Δ                   i   ξ       +     T   ξ                                    (       L   x0     +     M   x0       )        Δ                   i   ξ   ′       =         -   N            ∂     Φ   b1         ∂     y   b            Δ                   ξ   ′       -     R                 Δ                   i   ξ       +     e   ξ                             Δ                 ξ     =           -   Δ                     y   a       -     Δ                   y   b       +     Δ                   y   c       +     Δ                   y   d           2        l   θ                             Δ                   i   ξ       =           -   Δ                     i   ya       -     Δ                   i   yb       +     Δ                   i   yc       +     Δ                   i     y                 d             2        l   θ                             e   ξ     =           -   Δ                     e   ya       -     Δ                   e   yb       +     Δ                   e   yc       +     Δ                   e     y                 d             2        l   θ                                      
     Formula 5 is as follows:                          {                 I   θ                   Δ                   ψ   ab   ″       =         l   ψ   2            ∂     F   yb         ∂     y   b            Δ                 ψ     +       l   ψ   2            ∂     F   yb         ∂     i   b1            Δ                   i   ψ       +     T   ψ                                    (       L   x0     +     M   x0       )        Δ                   i   ψ   ′       =         -   N            ∂     Φ   b1         ∂     y   b            Δ                   ψ   ′       -     R                 Δ                   i   ψ       +     e   ψ                             Δ                 ψ     =         Δ                   y   a       -     Δ                   y   b       -     Δ                   y   c       +     Δ                   y   d           2        l   ψ                             Δ                   i   ψ       =         Δ                   i   ya       -     Δ                   i   yb       -     Δ                   i   yc       +     Δ                   i     y                 d             2        l   ψ                             e   ψ     =         Δ                   e   ya       -     Δ                   e   yb       -     Δ                   e   yc       +     Δ                   e     y                 d             2        l   ψ                                      
     With respect to the above formulas, Φ b  is a flux, M is a weight of the movable unit  4 , I θ , I ξ  and I ψ  are moments of inertia around respective y, x and z coordinates, U y  and U x  are the sum of external forces in the respective y-mode and x-mode, T θ , T ξ  and T ψ  are the sum of disturbance torques in the respective θ-mode, ξ-mode and ψ-mode, a symbol “′” represents a first time differentiation d/dt, a symbol “″” represents a second time differentiation d 2 /dt 2 , Δ is a infinitesimal fluctuation around :a steady levitated state, L x0  is a self-inductance of each coils  20  and  20 ′ at a steady levitated state, M x0  is a mutual inductance of coils  20  and  20 ′ at a steady levitated state, R is a reluctance of each coils  20  and  20 ′, N is the number of turns of each coils  20  and  20 ′, i y , i x , i θ , i ξ and i ψ  are exciting currents of the respective y, x, θ, ξ and ψ modes, e y , e x , e θ , e 86   and e ψ  are exciting voltages of the respective y, x, θ, ξ and ψ modes, l θ  is each of the spans of the magnet units  15   a  and  15   d , and of the magnet units  15   b  and  15   c , and l ψ  represents each of the spans of the magnet units  15   a  and  15   b , and of the magnet units  15   c  and  15   d.    
     Moreover, voltage equations of the remaining ζ, δ and γ modes are given as follows. 
     Formula 6 is as follows:                              (       L   x0     +     M   x0       )        Δ                   i   ζ   ′       =         -   N            ∂     Φ   b1         ∂     x   b            Δ                   ζ   ′       -     R                 Δ                   i   ζ       +     e   ζ                     Δ                 ζ     =         Δ                   x   a       +     Δ                   x   b       +     Δ                   x   c       +     Δ                   x   d         4                         Δ                   i   ζ       =         Δ                   i   xa       +     Δ                   i   xb       +     Δ                   i   xc       +     Δ                   i     x                 d           4                         e   ζ     =         Δ                   e   xa       +     Δ                   e   xb       +     Δ                   e   xc       +     Δ                   e     x                 d           4                                  
     Formula 7 is as follows:                              (       L   x0     -     M   x0       )        Δ                   i   δ   ′       =         -   N            ∂     Φ   b1         ∂     y   b            Δ                   δ   ″       -     R                 Δ                   i   δ       +     e   δ                     Δ                 δ     =         Δ                   y   a       -     Δ                   y   b       +     Δ                   y   c       -     Δ                   y   d           2        l   ψ                             Δ                   i   δ       =         Δ                   i   ya       -     Δ                   i   yb       +     Δ                   i   yc       -     Δ                   i     y                 d             2        l   ψ                             e   δ     =         Δ                   e   ya       -     Δ                   e   yb       +     Δ                   e   yc       -     Δ                   e     y                 d             2        l   ψ                                      
     Formula 8 is as follows:                              (       L   x0     +     M   x0       )        Δ                   i   γ   ′       =         -   N            ∂     Φ   b1         ∂     x   b            Δ                   γ   ′       -     R                 Δ                   i   γ       +     e   γ                     Δ                 γ     =         Δ                   x   a       +     Δ                   x   b       -     Δ                   x   c       -     Δ                   x   d           2        l   θ                             Δ                   i   γ       =         Δ                   i   xa       +     Δ                   i   xb       -     Δ                   i   xc       -     Δ                   i     x                 d             2        l   θ                             e   γ     =         Δ                   e   xa       +     Δ                   e   xb       -     Δ                   e   xc       -     Δ                   e     x                 d             2        l   θ                                      
     With respect to the above formulas, y is variation of the center of the movable unit  4  in the y-axis direction, x is variation of the center of the movable unit  4  in the x-axis direction, θ is a rolling angle about the y-axis, ξ is a pitching angle about the x-axis, ψ is a yawing angle about the z-axis, and the guide rails  2  and  2 ′ are the reference points. In case the optical path  7   a  (or  7   b ) is the reference point, a suffix “ab” is added. y ab  is a variation of the center of the movable unit  4  in the y-axis direction. x ab  is a variation of the center of the movable unit  4  in the x-axis direction. θ ab  is a rolling angle about the y-axis. ξ ab  is a pitching angle about the x-axis. ψ ab  is a yawing angle about the z-axis. Symbols y, x, θ, ξ and ψ of the respective modes are affixed to exciting currents i and exciting voltages e respectively. Further, symbols a-d representing which of the magnet units  15   a - 15   d  are respectively affixed to exciting currents i and exciting voltages e of the magnet units  15   a - 15   d . Levitation gaps x a -x d  and y a -y d  to the magnet units  15   a - 15   d  are made by a coordinate transformation into y, x, θ, ξ and ψ modes by the following formula 9. 
     Formula 9 is as follows:        y   =       1   4          (       y   a     +     y   b     +     y   c     +     y   d       )               x   =       1   4          (       -     x   a       +     x   b     +     x   c     -     x   d       )               θ   =       1     2        l   θ              (       -     x   a       +     x   b     -     x   c     +     x   d       )               ξ   =       1     2        l   θ              (       -     y   a       -     y   b     +     y   c     +     y   d       )               Ψ   =       1     2        l   ψ              (       y   a     -     y   b     -     y   c     +     y   d       )                              
     Exciting currents i a1 ,i a2 -i d1 , i d2  to the magnet units  15   a    15   d  are made a coordinate transformation into exciting currents i y , i x , i θ , i ξ , i ψ , i ζ , i δ  and i γ  the respective modes by the following formula 10. 
     Formula 10 is as follows:          i   y     =       1   8          (       i   a1     -     i   a2     +     i   b1     -     i   b2     +     i   c1     -     i   c2     +     i   d1     -     i   d2       )                 i   x     =       1   8          (       -     i   a1       -     i   a2     +     i   b1     +     i   b2     +     i   c1     +     i   c2     -     i   d1     -     i   d2       )                 i   θ     =       1     4        l   θ              (       -     i   a1       -     i   a2     +     i   b1     +     i   b2     -     i   c1     -     i   c2     +     i   d1     +     i   d2       )                 i   ξ     =       1     4        l   θ              (       -     i   a1       +     i   a2     -     i   b1     +     i   b2     +     i   c1     -     i   c2     +     i   d1     -     i   d2       )                 i   ψ     =       1     4        l   ψ              (       i   a1     -     i   a2     -     i   b1     +     i   b2     -     i   c1     +     i   c2     +     i   d1     -     i   d2       )                 i   ζ     =       1   8          (       i   a1     +     i   a2     +     i   b1     +     i   b2     +     i   c1     +     i   c2     +     i   d1     +     i   d2       )                 i   δ     =       1     4        l   ψ              (       i   a1     -     i   a2     -     i   b1     +     i   b2     +     i   c1     -     i   c2     -     i   d1     +     i   d2       )                 i   γ     =       1     4        l   θ              (       i   a1     +     i   a2     +     i   b1     +     i   b2     -     i   c1     -     i   c2     -     i   d1     -     i   d2       )                              
     Controlled input signals to levitation systems of the respective modes, for example, exciting voltages e y , e x , e θ , e ξ , e ψ , e ζ , e δ  and e γ  which are the outputs of the calculator  32 , are made by an inverse transformation to exciting voltages of the coils  20  and  20 ′ of the magnet units  15   a - 15   d  by the following formula 11. 
     Formula 11 is as follows:          e   a1     =       e   y     -     e   x     -         l   θ     2          e   θ       -         l   θ     2          e   ξ       +         l   ψ     2          e   ψ       +     e   ζ     +         l   ψ     2          e   δ       +         l   θ     2          e   γ                   e   a2     =       -     e   y       -     e   x     -         l   θ     2          e   θ       -         l   θ     2          e   ξ       -         l   ψ     2          e   ψ       +     e   ζ     -         l   ψ     2          e   δ       +         l   θ     2          e   γ                   e   b1     =       e   y     +     e   x     +         l   θ     2          e   θ       -         l   θ     2          e   ξ       -         l   ψ     2          e   ψ       +     e   ζ     -         l   ψ     2          e   δ       +         l   θ     2          e   γ                   e   b2     =       -     e   y       +     e   x     +         l   θ     2          e   θ       +         l   θ     2          e   ξ       +         l   ψ     2          e   ψ       +     e   ζ     +         l   ψ     2          e   δ       +         l   θ     2          e   γ                   e   c1     =       e   y     +     e   x     -         l   θ     2          e   θ       +         l   θ     2          e   ξ       -         l   ψ     2          e   ψ       +     e   ζ     +         l   ψ     2          e   δ       -         l   θ     2          e   γ                   e   c2     =       -     e   y       +     e   x     -         l   θ     2          e   θ       -         l   θ     2          e   ξ       +         l   ψ     2          e   ψ       +     e   ζ     -         l   ψ     2          e   δ       -         l   θ     2          e   γ                   e   d1     =       e   y     -     e   x     +         l   θ     2          e   θ       +         l   θ     2          e   ξ       +         l   ψ     2          e   ψ       +     e   ζ     -         l   ψ     2          e   δ       -         l   θ     2          e   γ                   e   d2     =       -     e   y       -     e   x     +         l   θ     2          e   θ       -         l   θ     2          e   ξ       -         l   ψ     2          e   ψ       +     e   ζ     +         l   ψ     2          e   δ       -         l   θ     2          e   γ                                
     With respect to the y, x, θ, ξ and ψ modes , since motion equations of the movable unit  4  pairs with voltage equations thereof, the formulas 15 are arranged to an equation of state shown in the following formula 12. 
     Formula 12 is as follows: 
     
       
         x 5 ′=A 5 x 5 +b 5 e 5 +p 5 h 5 +d 5 u 5   
       
     
     In the formula 12, vectors x 5 , A 5 , b 5 , p 5  and d 5 , and u 5  are defined as follows by formula 13. 
     Formula 13 is as follows:            x   5     =     [                             Δ                 y               Δ                   y   ab                       Δ                   y   ′                       Δ                   y   ab   ′                       Δ                   i   y             ]       ,     [                             Δ                 x               Δ                   x   ab                       Δ                   x   ′                       Δ                   x   ab   ′                       Δ                   i   x             ]     ,     [                             Δ                 θ               Δ                   θ   ab                       Δ                   θ   ′                       Δ                   θ   ab                       Δ                   i   θ             ]     ,       [           Δ                 ξ               Δ                   ξ   ab                 Δ                   ξ   ′                 Δ                   ξ   ab   ′                 Δ                   i   ξ             ]                     or              [           Δ                 ψ               Δ                   ψ   ab                 Δ                   ψ   ′                 Δ                   ψ   ab   ′                 Δ                   i   ψ             ]                 A   5     =     [         0       0       1       0       0           0       0       0       1       0             a   21         0       0       0         a   23               a   21         0       0       0         a   23             0       0         a   32         0         a   33           ]                 b   5     =     [         0           0           0           0             b   31           ]       ,       d   5     =     [         0           0             d   21               d   21             0         ]       ,       p   5     =     [         0           0             -   1             0           0         ]                   u   5     =     U   y       ,     U   x     ,     T   θ     ,     T   ξ     ,     or                   T   ψ                              
     wherein h 5  represents irregularities on the guide rail  2  ( 2 ′) to the optical path  7   a  ( 7   b ). 
     Where the following formula 14 is provided, h 5  is defined by a formula 15. 
     Formula 14 is as follows: 
     
       
         h y =y ab −y,h x =x ab −x,h θ =θ ab −θ 
       
     
     
       
         h ξ =ξ ab −ξ,h ψ =ψ ab −ψ 
       
     
     Formula 15 is as follows: 
     
       
         h 5 =h y ″,h x ″,h θ ″,h ξ ″,h ψ ″ 
       
     
     Further, e 5  is a controlling voltage for stabilizing the respective modes. 
     Formula 16 is as follows: 
     
       
         e 5 =e y ,e x ,e θ ,e ξ ″or″e ψ   
       
     
     The formulas 6-8 are arranged into an equation of state shown in the following formula 18, by defining a state variable as the following formula 17. 
     Formula 17 is as follows: 
     
       
         x 1 =Δi ζ ,Δi δ ,Δi γ   
       
     
     Formula 18 is as follows: 
     
       
         x 1 ′=A 1 x 1 +b 1 e 1+d   1 u 1   
       
     
     If offset voltages of the controller  32  in the respective modes are marked with v ζ , v δ  and v γ , A 1 , b 1 , d 1  and u 1  in each mode are presented as follows. 
     Formula 19 is as follows:        (ζ-mode)               A   l     =     -     R       L   x0     +     M   x0             ,       b   l     =     1       L   x0     +     M   x0           ,       d   l     =     1       L   x0     +     M   x0                     u   l     =         -   N            ∂     Φ   b1         ∂     x   b            Δ                   ζ   ′       +     v   ζ               (δ-mode)               A   l     =     -     R       L   x0     -     M   x0             ,       b   l     =     1       L   x0     -     M   x0           ,       d   l     =     1       L   x0     -     M   x0                     u   l     =         -   N            ∂     Φ   b1         ∂     y   b            Δ                   δ   ′       +     v   δ               (γ-mode)               A   l     =     -     R       L   x0     +     M   x0             ,       b   l     =     1       L   x0     +     M   x0           ,       d   1     =     1       L   x0     +     M   x0                     u   l     =         -   N            ∂     Φ   b1         ∂     x   b            Δ                   γ   ′       +     v   γ                              
     wherein e 1  is a controlling voltage of each mode. 
     Formula 20 is as follows: 
     
       
         e 1 =e ζ ,e δ ,ore γ   
       
     
     The formula 12 may achieve a zero power control by feedback of the following formula 21. 
     Formula 21 is as follows: 
     
       
         e 5 =F 5 x 5 +∫K 5 x 5 dt 
       
     
     In case of letting F a , F b , F c , F d  and F e  be proportional gains, and K e  be integral gain, the following formula 22 is given. 
     Formula 22 is as follows: 
     
       
         F 3 =[F a F b F c F d F e ] 
       
     
     
       
         K 3 =[0000K e ] 
       
     
     Likewise, the formula 18 may achieve a zero power control by feedback of the following formula 23. 
     Formula 23 is as follows: 
     
       
         e 1 =F 1 x 1 +∫K 1 x 1 dt 
       
     
     F 1  is a proportional gain. K 1  is an integral gain. 
     As shown in FIG. 5, the calculator  32 , which provides the above zero power control, comprises subtractors  41   a - 41   h ,  42   a - 42   h  and  43   a - 43   h , average calculators  44   x  and  44   y , a gap deviation coordinate transformation circuit  45 , a current deviation coordinate transformation circuit  46 , a controlling voltage calculator  47 , a controlling voltage coordinate inverse transformation circuit  48 , a vertical position calculator  49 , a position deviation coordinate transformation circuit  50 , and an irregularity memory circuit  51 . The calculator  32  providese not only the zero power control but also a guide control on the basis of a reference coordinate by detecting a position of the movable unit  4  by using the photodiodes  8   a ,  8   b  and  8   c , and the optical paths  7   a ,  7   b  and  7   c  formed by the laser radiators  6   a ,  6   b  and  6   c.    
     The subtractors  41   a - 41   h  calculate x-direction gap deviation signals Δg xa1 , Δg xa2 ,-Δg xd1 , Δg xd2  by subtracting the respective reference values x a01 , x a02 , -x d01 , x d02  from gap signals g xa1 , g xa2 ,-g xd1 , g xd2  from the x-direction gap sensors  13   a ,  13 ′ a - 13   d ,  13 ′ d . The subtractors  42   a - 42   h  calculate y-direction gap deviation signals Δg ya1 , Δg ya2 ,-Δg yd1 , Δg yd2  by subtracting the respective reference values y a01 , y a02 ,-y d01 , y d02  from gap signals g ya1  , g ya2  , g yd1  , g yd2  from the y-direction gap sensors  14   a ,  14 ′ a - 14   d ,  14 ′ d . The subtractors  43   a - 43   h  calculate current deviation signals Δi a1 , Δi a2 ,-Δi d1 , Δi d2  by subtracting the respective reference values i a01 , i a02 ,-i d01 , i d02  from exciting current signals i a1 , i a2 ,-i d1 , i d2  from current detectors  36   a ,  36 ′ a - 36   d ,  36 ′ d.    
     The average calculators  44   x  and  44   y  average the x-direction gap deviation signals Δg xa1 , Δg xa2 ,-Δg xd1 , Δg xd2 , and the y-direction gap deviation signals Δg ya1 , Δg ya2 ,-Δg yd1 , Δg yd2  respectively, and output the calculated x-direction gap deviation signals Δx a -Δx d , and the calculated y-direction gap deviation signals Δy a -Δy d . The gap deviation coordinate transformation circuit  45  calculates y-direction variation Δy of the center of the movable unit  4  on the basis of the y-direction gap deviation signals Δy a -Δy d , x-direction variation Δx of the center of the movable unit  4  on the basis of the x-direction gap deviation signals Δx a -Δx d , a rotation angle Δθ in the θ-direction(rolling direction) of the center of the movable unit  4 , a rotation angle Δξ in the ξ-direction(pitching direction) of the movable unit  4 , and a rotation angle Δψ in the ψ-direction(yawing direction) of the movable unit  4 , by the use of the formula 9. 
     The current deviation coordinate transformation circuit  46  calculates a current deviation Δi y  regarding y-direction movement of the center of the movable unit  4 , a current deviation Δi x  regarding x-direction movement of the center of the movable unit  4 , a current deviation Δi θ  regarding a rolling around the center of the movable unit  4 , a current deviation Δi ξ  regarding a pitching around the center of the movable unit  4 , a current deviation Δi ψ  regarding a yawing around the center of the movable unit  4 , and current deviations Δi ζ , Δi δ  and Δi γ , regarding ζ, δ and γ stressing the movable unit  4 , on the basis of the current deviation signals Δi a1 , Δi a   2 ,-Δi d1 , Δi d2  by using the formula 10. 
     The vertical position calculator  49  calculates a vertical position of the movable unit  4  in the hoistway  1  on the basis of the outputs of the photodiodes  8   b  and  8   c  disposed at the same level. The position deviation coordinate transformation circuit  50  calculates positions Δy ab , Δx ab , Δθ ab , Δξ ab  and Δψ ab  in each mode of the movable unit  4  on the reference coordinate on the basis of the outputs of the photodiodes  8   a  and  8   b , and outputs the calculated results to the controlling voltage calculator  47 . 
     The irregularity memory circuit  51  subtracts an output of the gap deviation coordinate transformation circuit  45  from a position of the movable unit  4  measured by the vertical position calculator  49  and an output of the position deviation coordinate transformation circuit  50 , and then consecutively stores irregularity data h y , h x , h θ , h ξ  and h ψ  of the guide rail  2 ( 2 ′) to the optical path  7   a  ( 7   b  ), which are transformed into a position of the movable unit  4 . The irregularity memory circuit  51  timely reads vertical position data and the irregularity data corresponding to a vertical position of the movable unit  4  and outputs them to the controlling voltage calculator  47 . 
     The controlling voltage calculator  47  calculates controlling voltages e y , e x , e θ , e ξ , e ψ , e ζ , e δ  and e γ  for magnetically and securely levitating the movable unit  4  in each of the y, x, θ, ξ, ψ, ζ, δ, and γ modes on the basis of the outputs Δy, Δx, Δθ, Δξ, Δψ, Δi y , Δi x , Δi θ , Δi ξ , Δi ψ , Δi ζ , Δi δ  and Δi γ  of the gap deviation coordinate transformation circuit  45  and the current deviation coordinate transformation circuit  46 . The controlling voltage coordinate inverse transformation circuit  48  calculates respective exciting voltages e a1 ,e a2 -e d1 ,e d2  of the magnet units  15   a - 15   d  on the basis of the outputs e y , e x , e θ , e ξ , e ψ , e ζ , e δ  and e γ  by the use of the formula 11, and feeds back the calculated result to the power amplifiers  33   a , 33 ′ a - 33   d , 33 ′ d.    
     The controlling voltage calculator  47  comprises a back and forth mode calculator  47   a , a right and left mode calculator  47   b , a roll mode calculator  47   c , a pitch mode calculator  47   d , a yaw mode calculator  47   e , an attractive mode calculator  47   f , a torsion mode calculator  47   g , and a strain mode calculator  47   h.    
     The back and forth mode calculator  47   a  calculates an exciting voltage e γ  in the y-mode on the basis of the formula  21  by using inputs Δy and Δi y . The right and left mode calculator  47   b  calculates an exciting voltage e x  in the x-mode on the basis of the formula 21 by using inputs Δx and Δi x . The roll mode calculator  47   c  calculates an exciting voltage e θ  in the θ-mode on the basis of the formula 21 by using inputs Δθ and Δi θ . The pitch mode calculator  47   d  calculates an exciting voltage e ξ  in the ξ-mode on the basis of the formula 21 by using inputs Δξ and Δi ξ . The yaw mode calculator  47   e  calculates an exciting voltage e ψ  in the ψ-mode on the basis of the formula 21 by using inputs Δψ and Δi ψ . The attractive mode calculator  47   f  calculates an exciting voltage e ζ  in the ζ-mode on the basis of the formula 23 by using input Δi ζ . The torsion mode calculator  47   g  calculates an exciting voltage e δ  in the δ-mode on the basis of the formula 23 by using input Δi δ . The strain mode calculator  47   h  calculates an exciting voltage e γ  in the γ-mode on the basis of the formula 23 by using input Δi γ . 
     FIG. 6 shows in detail each of the calculators  47   a - 47   e.    
     Each of the calculators  47   a - 47   e  comprises a differentiator  60  calculating time change rate Δy′, Δx′, Δθ′, Δξ′ or Δψ′ on the basis of each of the variations Δy, Δx, Δθ, Δξ and Δξ, a differentiator  61  calculating time change rate Δy′ ab , Δx′ ab , Δθ ab , Δξ ab  or Δψ′ ab  on the basis of each of the variations Δy ab , Δx ab , Δθ ab , Δξ ab  and Δψ ab  from the reference position, and gain compensators  62  multiplying each of the variations Δy-Δψ and Δy ab -Δψ ab , each of the time change rates Δy′-Δψ′ and Δy′ ab -Δψ′ ab  and each of the current deviations Δi y -Δi ψ , by an appropriate feedback gain respectively. Each of the calculators  47   a - 47   e  also comprises a current deviation setter  63 , a subtractor  64  subtracting each of the current deviations Δi y -Δi ψ  from a reference value output by the current deviation setter  63 , an integral compensator  65  integrating the output of the subtractor  64  and multiplying the integrated result by an appropriate feed back gain, an adder  66  calculating the sum of the outputs of the gain compensators  62 , and a subtractor  67  subtracting the output of the adder  66  from the output of the integral compensator  65 , and outputting the exciting voltage e y , e x , e θ , e ξ  or e ψ , of the respective y, x, θ, ξ and ψ modes. The gain compensator  62  and the integral compensator  65  may change a set gain on the basis of vertical position data H and the irregularity data h y , h x , h θ , h ξ  and h ψ  corresponding to a vertical position of the movable unit  4 . 
     FIG. 7 shows internal components in common among the calculators  47   f - 47   h.    
     Each of the calculators  47   f - 47   h  comprises a gain compensator  71  multiplying the current deviation Δi ζ , Δi δ  or Δi γ  by an appropriate feedback gain, a current deviation setter  72 , a subtractor  73  subtracting the current deviation Δi ζ , Δi δ  or Δi γ  from a reference value output by the current deviation setter  72 , an integral compensator  74  integrating the output of the subtractor  73  and multiplying the integrated result by an appropriate feedback gain, and a subtractor  75  subtracting the output of the gain compensator  71  from the output of the integral compensator  74  and outputting an exciting voltage e ζ , e δ  or e γ  of the respective ζ, δ and γ modes. 
     The following explains an operation of the above-described guide system of the first embodiment of the present invention. 
     Any of the ends of the center cores  16  of the magnet units  15   a - 15   d , or the ends of the electromagnets  18  and  18 ′ of the magnet units  15   a - 15   d  adsorb to the facing surfaces of the guide rails  2  and  2 ′ through the solid lubricating materials  22  at a stopping state of the magnetic guide system. At this time, an upward and downward movement of the movable unit  4  is not interfered with because of the effect of the solid lubricating materials  22 . 
     Once the guide system is activated at the stopping state, fluxes of the electromagnets  18  and  18 ′, which possesses the same or opposite direction of fluxes generated by the permanent magnets  17  and  17 ′, are controlled by the controller  30 . The controller  30  controls exciting currents to the coils  20  and  20 ′ in order to keep a predetermined gap between the magnet units  15   a - 15   d  and guide rails  2  and  2 ′. Consequently, as shown in FIG. 4, a magnetic circuit Mcb is formed with a path of the permanent magnet  17 , the L-shaped core  19 , the core plate  21 , the gap Gb, the guide rail  2 ′, the gap Gb″, the center core  16 , and the permanent magnet  17 ; and a magnetic circuit Mcb′ is formed with a path of the permanent magnet  17 ′, the L-shaped core  19 ′, the core plate  21 ′, the gap Gb′, the guide rail  2 ′, the gap Gb″, the center core  16 , and the permanent magnet  17 ′. The gaps Gb, Gb′ and Gb″ , or other gaps formed with the magnet units  15   a ,  15   c  and  15   d , are set to certain distances so that magnetic attractive forces of the magnet units  15   a - 15   d  generated by the permanent magnets  17  and  17 ′ balance with a force in the y-direction (back and force direction) acting on the center of the movable unit  4 , a force in the x-direction (right and left direction), and torques acting around the x, y and x-axis passing on the center of the movable unit  4 . When some external forces operate on the movable unit  4 , the controller  30  controls exciting currents flowing into the electromagnets  18  and  18 ′ of the respective magnet units  15   a - 15   d  in order to keep such balance, thereby achieving the so-called zero power control. 
     Now, the movable unit  4  is positioned at the lowest floor. The movable unit  4 , which is controlled to be guided with no contact by the zero power control, starts to move upwardly by a hoisting machine (not shown). In this first upward stage, the movable unit moves slowly enough so that the zero power control can control to follow irregularities on the guide rails. During the first initial running, positions H of the movable unit  4  and the irregularity data h y , h x , h θ , h ξ  and h ψ  are stored in the irregularity memory circuit  51 . Consequently, outputs of the irregularity memory circuit  51  are zero during the first initial running. After the first initial running and storing of the position data H and the irregularity data from the lowest floor to the highest floor, the collected data is used for the next running. The position data H and the irregularity data may be rewritten in the same way as the above-described method at any time, if necessary. 
     After the first initial running, a guide control is carried out as follows. When the movable unit  4  passes relatively gentle irregularities such as warps, a shake of the movable unit  4  caused by irregularities on the guide rails  2  and  2 ′ may be restrained effectively, since the controller  30  feeds back each of the variations Δy-Δψ and Δy ab -Δψ ab  and each of the time change rates Δy′-Δψ′ and Δy′ ab -Δψ′ ab  to each of the exciting voltages e y , e x , e θ , e ξ  and e ψ  via the gain compensator  62 . 
     Since the irregularity data h y , h x , h θ , h ξ  and h ψ  and the vertical position data H are read out by the irregularity memory circuit  51  and the gain compensator  62  and the integral compensator  65  input these data, the gain compensator  62  and the integral compensator  65  may change controlling parameters at intervals having irregularities during a later running, if vertical position data and the intervals having irregularities are set to the gain compensator  62  and the integral compensator  65  after the initial running. 
     Even if a difference in level or a gap caused by a repetition of thermal expansion and contraction or an earthquake occur at a joint of the guide rail  2 ( 2 ′), a shake of the movable unit  4  may be restrained by changing controlling parameters so that guiding forces of the magnet units  15   a - 15   d  possess an extremely low spring constant on the condition that the movable unit  4  positions at the interval having irregularity, a velocity of the movable unit  4  is fast, and a change rate of the irregularity data h y , h x , h θ , h ξ  and h ψ  exceeds the predetermined value. 
     In case the magnetic guide system stops working, the current deviation setters  62  for the y-mode and the x-mode set reference values from zero to minus values gradually, whereby the movable unit  4  gradually moves in the y and x-directions. At last, any of the ends of the center cores  16  of the magnet units  15   a - 15   d , or the ends of the electromagnets  18  and  18 ′ of the magnet units  15   a - 15   d  adsorb to the facing surfaces of the guide rails  2  and  2 ′ through the solid lubricating materials  22 . If the magnetic guide system is stopped at this state, a reference value of the current deviation setter  62  is reset to zero, and the movable unit  4  adsorbs to the guide rails  2  and  2 ′. 
     In the first embodiment, although the zero power control, which controls to settle an exciting current for an electromagnet to zero at a steady state, is adopted for no contact guide control, various other control methods for controlling attractive forces of the magnet units  15   a - 15   d  may be used. For example, a control method, which controls to keep the gaps constant, may be adopted, if the magnet units areto follow the guide rails  2  and  2 ′ more precisely. 
     A guide system of a second embodiment of the present invention is described with reference to FIGS. 8 and 9. 
     In the first embodiment, although no contact guide control is achieved by adopting the magnet units  15   a - 15   d  as guide units  5   a - 5   d , it is not limited to the above described system. As shown in FIGS. 8 and 9, guide units  100   a - 100   d  in a wheel supporting type may be attached to the upper and lower corners of the movable unit  4  in the same way as the first embodiment. Although only guide unit  100   b  is illustrated in FIGS. 8 and 9, the other guide units  100   a ,  100   c  and  100   d  have the same structure as the guide unit  100   b.    
     The guide unit  100   b  of the second embodiment comprises three guide wheels  111 ,  112  and  113  disposed to surround the guide rail  2 ( 2 ′) on three sides, suspension units  114 ,  115  and  116 , disposed between the respective guide wheels  111 - 113  and the movable unit  4 , operating guiding forces on the guide rail  2 ( 2 ′) by pressing the guide wheels  111 - 113 , and a base supporting the suspension units  114 - 116 . 
     Each of the guide units  100   a - 110   d  is fixed to a corresponding corner of the frame  11  through the base  117 . The suspension units  114 - 116  each include a respective one of linear pulse motors  121 ,  122  and  123 , suspensions  124 ,  125  and  126 , and potentiometers  127 ,  128  and  129  for gap sensors. 
     The linear pulse motors  121 - 123  comprise respectively stators  131 ,  132  and  133 , and linear rotors  134 ,  135  and  136 . The linear rotors  134 - 136  move along concave grooves of the stators  131 - 133  formed in the shape of a U as a whole. Moving speeds of the linear rotors  134 - 136  correspond to values of speed signals individually provided to pulse motor drivers  141 ,  142  and  143  of the linear pulse motors  121 - 123 . 
     The suspensions  124 - 126  comprise L-shaped plates  144 ,  145  and  146 (not shown) fixed on the linear rotors  134 - 136 , supports  151 (not shown),  152  and  153 (not shown) fixed on the L-shaped plates  144 - 146  and including axles  147 ,  148  and  149  on the opposite sides thereof, pairs of plates  157   a  and  157   b ,  158   a  and  158   b , and  159   a  and  159   b  pivotably connected to the supports  151 - 153  by putting the axles  147 - 149  between the pairs of plates  157   a , 157   b - 159   a , 159   b  at the basal portion thereof, and supporting the guide wheels rotatably by the axles  154 ,  155  and  156  at the tips thereof by putting the supports  151 - 153  and the guide wheels  111 - 113  between the pairs of plates  157   a , 157   b    159   a , 159   b . The suspensions  124 - 126  also comprise coil springs  161 ,  162  and  163 , guiding rods  164 ,  165  and  166  put through the coil springs  161 - 163  and fixed to the L-shaped plates  144 - 146  at the rear ends thereof, and guards  167 ,  168  and  169  fixed at a position that the each coil spring  161 - 163  operates a predetermined pressing force on the pairs of plates  157   a , 157   b - 159   a , 159   b , and pierced through the guiding rods  164 - 166 . 
     The potentiometers  127 - 129  detect turning angles of the pairs of plates  157   a , 157   b - 159   a , 159   b  around the axes  147 - 149  of the supports  151 - 153 , and function as gap sensors outputing a distance between the guide rail  2 ( 2 ′) and the center of each axles  154 ,  155  and  156 . 
     A guiding force of each guide wheel  111 - 113  of the guide units  100   a - 100   d  is controlled by a controller  230  shown in FIG. 10, thereby guiding the elevator cage  10  and the frame  11  against the guide rails  2  and  2 ′. 
     The controller  230  is divided and disposed at the same position as the controller  30  of the first embodiment shown in FIG. 1, but functionally combined as a whole as shown in FIG.  10 . The following is an explanation of the controller  230 . In FIG. 10, arrows represent signal paths, and solid lines represent electric power lines. In the following description, identical numerals are added to the same components as the controller  30  of the first embodiment. Further, suffixes “a”-“d” are respectively added to figures indicating the main components of the respective guide units  100   a - 100   d  in order to indicate instaling positions on the frame  11 . 
     The controller  230 , fixed on the frame  11 , comprises a sensor  231  detecting a distance between the guide rail  2 ( 2 ′) and the center of each guide wheel  111   a ,  112   a ,  113   a - 111   d ,  112   d ,  113   d  of the guide units  100   a - 100   d , a calculator  232  calculating a moving speed of each of the moving elements  134 - 136  of the linear pulse motors  121   a ,  122   a ,  123   a - 121   d ,  122   d ,  123   d  for guiding the movable unit  4  in response to output signals from the sensor  231 , pulse motor drivers  211   a ,  212   a ,  213   a - 211   d ,  212   d ,  213   d  driving each moving element  134 - 136  at a designated speed on the basis of outputs of the calculator  232 , thereby controlling a guiding force of each guide wheel  111   a ,  112   a ,  113   a - 111   d ,  112   d ,  113   d  in both x and y directions individually. 
     A power supply  234  supplies an electric power to the linear pulse motors  121   a ,  122   a ,  123   a - 121   d ,  122   d ,  123   d  through pulse motor drivers  211   a ,  212   a ,  213   a - 211   d ,  212   d ,  213   d  and also supplies an electric power to a constant voltage generator  235  supplying an electric power having a constant voltage to the calculator  232 , and the potentiometers  127   a ,  128   a ,  129   a - 127   d ,  128   d ,  129   d  constituting x-direction gap sensors and y-direction gap sensors. The constant voltage generator  235  supplies an electric power with a constant voltage to the calculator  232  and the potentiometers  127   a ,  128   a ,  129   a - 127   d ,  128   d ,  129   d , even if a voltage of the power supply  234  varies due to an excessive current supply, whereby the calculator  232  and the potentiometers  127   a ,  128   a ,  129   a - 127   d ,  128   d ,  129   d  may normally operate. 
     The sensor  231  comprises the potentiometers  127   a ,  128   a ,  129   a - 127   d ,  128   d ,  129   d  and the photodiodes  8   a - 8   c.    
     Likewise the first embodiment, the calculator  232  controls a guide control for the movable unit  4  in every motion coordinate system shown in FIG.  1 . The motion coordinate system includes a y-mode (back and forth motion mode) representing a right and left motion along a y-coordinate on a center of the movable unit  4 , an x-mode (right and left motion mode) representing a right and left motion along a x-coordinate, a θ-mode (roll mode) representing a rolling about the center of the movable unit  4 , a ξ-mode (pitch mode) representing a pitching about the center of the movable unit  4 , and a ψ-mode (yaw-mode) representing a yawing about the center of the movable unit  4 . 
     To simplify the explanation, it is assumed that a center of the movable unit  4  ist on a vertical line crossing a diagonal intersection point of the center points of the guide units  100   a - 100   d  disposed on four corners of the movable unit  4 . Where the center is regarded as the origin of respective x, y and z coordinate axes, a motion equation in every mode is given by the following formulas 24 through 28. 
     Formula 24 is as follows:          M                 Δ                   y   ab   ″       =         -   8          K   s        Δ                 y     -     8                   η   s        Δ                   y   ′       -     8        K   s          v   y       +     U   y                 Δ                 y     =         Δ                   y   a1       -     Δ                   y   a2       +     Δ                   y   b1       -     Δ                   y   b2       +     Δ                   y   c1       -     Δ                   y   c2       +     Δ                   y   d1       -     Δ                   y   d2         8               v   y     =         v   a1     -     v   a2     +     v   b1     -     v   b2     +     v   c1     -     v   c2     +     v   d1     -     v   d2       8                            
     Formula 25 is as follows:          M                 Δ                   x   ab   ″       =         -   4          K   s        Δ                 x     -     4                   η   s        Δ                   x   ′       -     4        K   s          v   x       +     U   x                 Δ                 x     =           -   Δ                     x   a       +     Δ                   x   b       +     Δ                   x   c       -     Δ                   x   d         4               v   x     =         -     v   a3       +     v   b3     +     v   c3     -     v   d3       4                            
     Formula 26 is as follows:            I   θ        Δ                   θ   ab   ″       =         -     K   s            l   θ   2        Δ                 θ     -       η   s          l   θ   2        Δ                   θ   ′       -       K   s          l   θ   2          v   θ       +     T   θ                 Δ                 θ     =           -   Δ                     x   a       +     Δ                   x   b       -     Δ                   x   c       +     Δ                   x   d           2        l   θ                   v   θ     =         -     v   a3       +     v   b3     -     v   c3     +     v   d3         2        l   θ                                
     Formula 27 is as follows:                        I   ξ        Δ                   ξ   ab   ″       =         -   2          K   s          l   θ   2        Δ                 ξ     -     2        η   s          l   θ   2        Δ                   ξ   ′       -     2        K   s          l   θ   2          v   ξ       +     T   ξ                     Δ                 ξ     =           -   Δ                     y   a1       +     Δ                   y   a2       -     Δ                   y   b1       +     Δ                   y   b2       +     Δ                   y   c1       -     Δ                   y   c2       +     Δ                   y   d1       -     Δ                   y   d2           4        l   θ                             v   ξ     =         -     v   a1       +     v   a2     -     v   b1     +     v   b2     +     v   c1     -     v   c2     +     v   d1     -     v   d2         4        l   θ                                      
     Formula 28 is as follows:                        I   θ        Δ                   ψ   ab   ″       =         -   2          K   s          l   ψ   2        Δ                 ψ     -     2        η   s          l   ψ   2        Δ                   ψ   ′       -     2        K   s          l   ψ   2          v   ψ       +     T   ψ                     Δ                 ψ     =         Δ                   y   a1       -     Δ                   y   a2       +     Δ                   y   b1       -     Δ                   y   b2       -     Δ                   y   c1       +     Δ                   y   c2       -     Δ                   y   d1       +     Δ                   y   d2           4        l   θ                             v   ψ     =         v   a1     -     v   a2     +     v   b1     -     v   b2     -     v   c1     +     v   c2     -     v   d1     +     v   d2         4        l   ψ                                      
     Ks is a spring constant of each suspension  124 - 126  per a unit moving distance of each guide wheel  111 - 113 . The term η s  is a damping constant of each suspension  124 - 126  per a unit moving distance of each guide wheel  111 - 113 . The terms v y , v x , v θ , v ξ  and v 104   are moving speed command values of moving elements 134136 in the respective y, x, θ, ξ and ψ modes. 
     Gaps x a -x d  and y a1 , y a2 -y d1 , y d2  corresponding to suspension units  114 - 116  are made by a coordinate transformation into y, x, θ, ξ and ψ coordinates by the following formula 29. 
     Formula 29 is as follows:        y   =       1   8          (       y   a1     -     y   a2     +     y   b1     -     y   b2     +     y   c1     -     y   c2     -     y   d1     +     y   d2       )               x   =       1   4          (       -     x   a       +     x   b     +     x   c     -     x   d       )               θ   =       1     2        l   θ              (       -     x   a       +     x   b     -     x   c     +     x   d       )               ξ   =       1     2        l   θ              (       -     y   a1       +     y   a2     -     y   b1     +     y   b2     +     y   c1     -     y   c2     +     y   d1     -     y   d2       )               ψ   =       1     2        l   ψ              (       y   a1     -     y   a2     -     y   b1     +     y   b2     -     y   c1     +     y   c2     +     y   d1     -     y   d2       )                              
     Controlled input signals to suspension systems of the respective modes, for example, moving speed command values v y , v x , v θ , v ξ  and v ψ  which are the outputs of the calculator  232  are made by an inverse transformation to velocity inputs v a1 , v a2 , v a3 -v d1 , v d2 , v d3  of the pulse motor drivers  211   a , 212   a , 213   a - 211   d , 212   d , 213   d  by the following formula 30. 
     Formula 30 is as follows:            v   a1     =       v   y     -         l   θ     2          v   ξ       +         l   ψ     2          v   ψ           ,       v   a2     =       -     v   y       +         l   θ     2          v   ξ       -         l   ψ     2          v   ψ           ,       v   a3     =       -     v   x       -         l   θ     2          v   θ                       v   b1     =       v   y     -         l   θ     2          v   ξ       -         l   ψ     2          v   ψ           ,       v   b2     =       -     v   y       +         l   θ     2          v   ξ       +         l   ψ     2          v   ψ           ,       v   b3     =       v   x     -         l   θ     2          v   θ                       v   c1     =       v   y     +         l   θ     2          v   ξ       -         l   ψ     2          v   ψ           ,       v   c2     =       -     v   y       -         l   θ     2          v   ξ       +         l   ψ     2          v   ψ           ,       v   c3     =       v   x     -         l   θ     2          v   θ                       v   d1     =       v   y     +         l   θ     2          v   ξ       +         l   ψ     2          v   ψ           ,       v   d2     =       -     v   y       -         l   θ     2          v   ξ       -         l   ψ     2          v   ψ           ,       v   d3     =       -     v   x       +         l   θ     2          v   θ                                  
     Motion equations of the movable unit  4  with respect to the y, x, θ, ξ and ψ modes expressed by formulas 24-28 are arranged to an equation of state shown in the following formula 31. 
     Formula 31 is as follows: 
     
       
         x′ 5 =A 5 x 5 +b 5 v 5 +p 5 h 5 +d 5 u 5   
       
     
     In the formula 31, vectors x 5 , A 5 , b 5 , p 5  and d 5 , and u 5  are defined as follows. 
     Formula 32 is as follows:            x   5     =     [                             Δ                 y               Δ                   y   ab                       Δ                   y   ′                       Δ                   y   ab   ′                       v   y           ]       ,     [                             Δ                 x               Δ                   x   ab                       Δ                   x   ′                       Δ                   x   ab   ′                       v   x           ]     ,     [                             Δ                 θ               Δ                   θ   ab                       Δ                   θ   ′                       Δ                   θ   ab   ′                       v   θ           ]     ,       [           Δ                 ξ               Δ                   ξ   ab                 Δ                   ξ   ′                 Δ                   ξ   ab   ′                 v   ξ           ]                     or              [           Δ                 ψ               Δ                   ψ   ab                 Δ                   ψ   ′                 Δ                   ψ   ab   ′                 v   ψ           ]                 A   5     =     [         0       0       1       0       0           0       0       0       1       0             a   21         0         a   22         0         a   21               a   21         0         a   22         0         a   21             0       0       0       0       0         ]                 b   5     =     [         0           0           0           0             b   31           ]       ,       d   5     =     [         0           0             d   21               d   21             0         ]       ,       p   5     =     [         0           0             -   1             0           0         ]                   u   5     =     U   y       ,     U   x     ,     T   θ     ,       T   ξ                   or                   T   ψ                              
     The term h 5  representing irregularities on the guide rails  2  and  2 ′ against the reference optical paths  7   a  and  7   b  is defined by the following formula 34, where the following formula 33 is provided. 
     Formula 33 is as follows: 
     
       
         h y =y ab −y,h x =x ab −x,h θ =θ ab −θ 
       
     
     
       
         h ξ=ξ   ab −ξ,h ψ =ψ ab −ψ 
       
     
     Formula 34 is as follows: 
     
       
         h 5 =h″ y ,h″ x ,h″ θ, h″   ξ orh″ ψ   
       
     
     Further, v 5  is a velocity input to the linear pulse motor for stabilizing the motion in each mode. 
     Formula 35 is as follows: 
     
       
         v 5 =v y ,v x ,v θ ,v ξ orv ψ   
       
     
     The formula 31 provides guide control by feeding back the following formula 36. 
     Formula 36 is as follows: 
     
       
         v 5 =F 5 x 5 +∫K 5 x 5 dt 
       
     
     Where proportional gains are represented by F a , F b , F c , F d  and F e  and an integral gain is represented by K e , F 5  and K 5  are expressed by the following formula 37. 
     Formula 37 is as follows: 
     
       
         F 5 =[F a F b F c F d F e ] 
       
     
     
       
         K 5 =[0K e 000] 
       
     
     As shown in FIG. 10, the calculator  232  comprises subtractors  241   a - 241   d  and  242   a - 242   h , a gap deviation coordinate transformation circuit  245 , a speed calculator  247 , a speed coordinate inverse transformation circuit  248 , a vertical position calculator  49 , a position deviation coordinate transformation circuit  50 , and an irregularity memory circuit  51 . 
     The subtractors  241   a - 241   d  calculate x-direction gap deviation signals Δg xa -Δg xd  by subtracting the respective reference values x a0 -x d0  from gap signals g xa -g xd  from the potentiometers  129   a - 129   d  constituting x-direction gap sensors. The subtractors  242   a - 242   h  calculate y-direction gap deviation signals Δg ya1 , Δg ya2 -Δg yd1 , Δg yd2  by subtracting the respective reference values y a01 , y a02 -y d01, y   d02  from gap signals g ya1 , g ya2 ,-g yd1 , g yd2  from the potentiometer  127   a ,  128   a - 127   d ,  128   d  constituting y-direction gap sensors. 
     The gap deviation coordinate transformation circuit  245  calculates y-direction variation Δy of the center of the movable unit  4  on the basis of the y-direction gap deviation signals Δg ya1 , Δg ya2 -Δg yd1 , Δg yd2 , x-direction variation Δx of the center of the movable unit  4  on the basis of the x-direction gap deviation signals Δg xa -Δg xd , a rotation angle Δθ in the θ-direction(rolling direction) of the center of the movable unit  4 , a rotation angle Δξ in the ξ-direction(pitching direction) of the movable unit  4 , and a rotation angle Δψ in the ψ-direction(yawing direction) of the movable unit  4 , by the use of the formula 29. 
     The vertical position calculator  49  calculates a vertical position of the movable unit  4  on the basis of the outputs of the two-dimensional photodiode  8   b  and the one-dimensional photodiode  8   c  disposed at the same level. The position deviation coordinate transformation circuit  50  calculates deviation positions Δy ab , Δx ab , Δθ ab , Δξ ab  and Δψ ab  of the movable unit  4  in every mode about the reference coordinates on the basis of the outputs of the two-dimensional photodiodes  8   a  and  8   b , and outputs the calculated results to the speed controller  247 . The irregularity memory circuit  51  subtracts an output of the gap deviation coordinate transformation circuit  245  from a position of the movable unit  4  measured by the vertical position calculator  49  and an output of the position deviation coordinate transformation circuit  50 , and then consecutively stores irregularity data h y , h x , h θ , h ξ  and h ψ  of the guide rail  2 ( 2 ′) to the optical path  7   a  ( 7   b  ) which are transformed into a position of the movable unit  4 . The irregularity memory circuit  51  timely reads vertical position data and the irregularity data corresponding to a vertical position of the movable unit  4  and outputs them to the speed calculator  247 . 
     The speed calculator  247  calculates each speed command v y , v x , v θ, v   ξ  and v ψ  of the moving elements  134 - 136  in the respective modes for guiding the movable unit  4  in each y, x, θ, ξ and ψ mode on the basis of outputs Δy, Δx, Δθ, Δξ and Δψ of the gap deviation coordinate transformation circuit  245 . The speed coordinate inverse transformation circuit  248  calculates each moving speed v a1 ,v a2 , v a3 -v a1 , v a2 ,v a3  of the moving elements  134 - 136  of the suspension units  114   a ,  115   a ,  116   a - 114   d ,  115   d ,  116   d  on the basis of outputs v y , v x , v θ , v ξ  and v 104   of the speed calculator  247  by using the formula 30, and feeds back the calculated results to the pulse motor drivers  211   a ,  212   a ,  213   a - 211   d ,  212   d ,  213   d.    
     The speed calculator  247  comprises a back and forth mode calculator  247   a , a right and left mode calculator  247   b , a roll mode calculator  247   c , a pitch mode calculator  247   d , and a yaw mode calculator  247   e.    
     The back and forth mode calculator  247   a  calculates a moving speed v y  in the y-mode on the basis of the formula 36 by using inputs Δy and Δy ab . The right and left mode calculator  247   b  calculates a moving speed v x  in the x-mode on the basis of the formula 36 by using inputs Δx and Δx ab . The roll mode calculator  247   c  calculates a moving speed v θ in the θ-mode on the basis of the formula 36 by using inputs Δθ and Δθ ab . The pitch mode calculator  247   d  calculates a moving speed v ξ in the ξ-mode on the basis of the formula 36 by using inputs Δξ and Δξ ab . The yaw mode calculator  247   e  calculates a moving speed v ψ  in the ψ-mode on the basis of the formula 36 by using inputs Δψ and Δψ ab . 
     FIG. 11 shows in detail each of the calculators  247   a - 247   e.    
     Each of the calculators  247   a - 247   e  comprises a differentiator  260  calculating time change rate Δy′, Δx′, Δθ′, Δξ′ or Δψ′ on the basis of each of the gap variations Δy, Δx, Δθ, Δξ and Δψ, a differentiator  261  calculating time change rate Δy′ ab , Δx′ ab , Δθ′ ab , Δξ′ ab  or Δψ′ ab  on the basis of each of the variation Δy ab , Δx ab , Δθ ab , Δξ ab  and Δψ ab  from the reference position, and an integrator  268  integrating each moving speed v y , v x , v θ , v ξ  and v ψ  in the respective modes and outputting moving distances l y , l x , l θ , l ξ  and l ψ , gain compensators  262  multiplying each of the variations Δy-Δψ and Δy ab -Δψ ab , each of the time change rates Δy′-Δψ′ and Δy′ ab -Δψ′ ab  and each of the moving distances l y -l ψ , by an appropriate feedback gain respectively. Each of the calculators  247   a - 247   e  also comprises a coordinate deviation setter  263 , a subtractor  264  subtracting each of the variation Δy ab -Δψ ab   from a reference value output by the coordinate deviation setter  263 , an integral compensator  265  integrating the output of the subtractor  264  and multiplying the integrated result by an appropriate feed back gain, an adder  266  calculating the sum of the outputs of the gain compensators  262 , and a subtractor  267  subtracting the output of the adder  266  from the output of the integral compensator  265 , and outputting the moving speeds v y , v x , v θ , v ξ  and v ψ , of the respective y, x, θ, ξ and ψ modes. The gain compensator  262  and the integral compensator  265  may change a set gain on the basis of vertical position data H and the irregularity data h y , h x , h θ , h ξ  and h ψ  corresponding to a vertical position of the movable unit  4 . 
     The following explains an operation of the above-described guide system of the second embodiment of the present invention. 
     In case the movable unit  4 , which is guided with the guide units  100   a - 100   d , starts to move upwardly by a hoisting machine(not shown) and passes relatively gentle irregularities such as warps, a shake of the movable unit  4  caused by irregularities on the guide rails  2  and  2 ′ may be restrained effectively, since the controller  230  feeds back each of the variations Δy ab -Δξ ab , and each of the time change rates Δy′ ab -Δψ′ ab  to each of the moving speed v y , v x , v θ , v ξ  and v ψ  via the gain compensator  262 . 
     Likewise the first embodiment, since the irregularity data h y , h x , h θ , h ξ  and h ψ  and the vertical position data H are read out by the irregularity memory circuit  51 , and the gain compensator  262  and the integral compensator  265  input these data, the gain compensator  262  and the integral compensator  265  may change controlling parameters at intervals having irregularities. 
     Even if a difference in level or a gap caused by a repetition of thermal expansion and contraction or an earthquake occur at a joint of the guide rail  2 ( 2 ′), a shake of the movable unit  4  may be restrained to a minimum by changing controlling parameters so that guiding forces of the guide units  100   a - 100   d  possess an extremely low spring constant. 
     The following is an explanation of a guide system of a third embodiment of the present invention. According to the first and second embodiments, the photodiodes  8   a - 8   c  directly receive lasers radiated by the laser radiators  6   a - 6   c  as shown FIG.  1 . However, the optical paths  7   a - 7   c  are not limited to the above, and other constructions shown in FIG. 12 may be adopted. That is, the elevator cage  10  includes supports  302  fixing mirrors  301  facing the cage  10  at a 45 degree angle, and includes the photodiodes  8   a - 8   c  on the side surface thereof, whereby the optical paths  7   a - 7   c  made a right-angled turn reach to the photodiodes  8   a - 8   c.    
     According to the third embodiment, since the surfaces of the photodiodes  8   a - 8   c  are disposed at a right angle, the surfaces are hardly covered with dust, thereby enabling a long term use without cleaning. 
     In the first, second and third embodiments, three laser radiators are used for forming three optical paths  7   a - 7   c . However, the number of the laser radiators are not limited to the above system, one optical path  7   b  may be divided into two optical paths by attaching a half mirror  311  fixed with two supports  312  as shown in FIG.  13 . 
     In this case, the half mirror  311  on the optical path  7   b  generates a transmitted light T 1  and a reflected light Tb perpendicular to the transmitted light T 1 . The transmitted light T 1  is incident on a mirror  314  slightly tilted and disposedt on the bottom of the hoistway  1  through a base  313 . The reflected light Tb is incident on the photodiode  8   b.    
     An optical axis of the transmitted light T 1  is reflected in a slightly inclining direction on the y and z coordinate plane and incident on the photodiode  8   c  by being reflected by a mirror  301 ′ facing downward fixed on the side of the elevator cage  10  through a support  302 ′ at a position adjacent to the half mirror  311 . 
     According to the above optical system, the same guide control as the first and second embodiments may be achieved. Further, since relatively expensive laser radiators are reduced from three to two, an elevator system cost may be reduced. 
     Moreover, as shown in FIG. 14, an optical path created by only one laser radiator  6   d  may be divided into two with a half mirror  321  and a mirror  322 . In this case, since the photodiode  8   c  is eliminated and the only photodiodes  8   a  and  8   b  are used, a vertical position of the movable unit  4  is not detected. The number of optical paths may be voluntarily selected as desired. 
     Further, in the above embodiments, although laser oscillating tubes are respectively adopted as the laser radiators  6   a ,  6   b  and  6   c , laser emitting semiconductor devices may be substituted for the laser oscillating tubes. Furthermore, the controllers  30  and  230  may be constituted of either an analog circuit or a digital circuit. 
     According to the present invention, since a position correction against a shake of a movable unit is executed on the basis of a gap between an optical path forming a reference position and the movable unit, and when the movable unit passes a position corresponding to an irregularity on a guide rail which is stored in advance during the initial running, an antiphase force is operated on the guide rail against the irregularity or the shake of the movable unit, the shake may be restrained, thereby improving a comfortable ride. 
     Further, since a plurality of optical paths is formed, a position correction against a shake of a movable unit may be executed by detecting gaps around a plurality of axes, for example, a horizontal axis and a vertical axis. 
     Furthermore, since a hoistway is a dark place, even a relatively low power laser radiator may create a reference optical path, thereby dispensing with a cooler system and enabling to form a reference optical path at a low cost. 
     Moreover, since an optical path is slightly inclined against a vertical line and a one-dimensional photodiode is disposed on the optical path, a vertical position of the movable unit may be detected on the basis of the incident position of a coherent light on the photodiode, especially a position corresponding to an irregularity on a guide rail may be detected during an initial running. 
     Further, since a two-dimensional photodiode is disposed on a vertical optical path, a gap position of the movable unit may be detected on the basis of the incident position of a coherent light on the photodiode. Since two two-dimensional photodiodes are disposed at the different levels and disposed on a respective vertical optical paths, three-dimensional position of the movable unit may be detected and corrected on the basis of the incident positions of the coherent lights on the photodiodes. 
     Furthermore, a magnetic levitation force generated from electromagnets is used for a guide system, the movable unit may be guided with no contact with guide rails, thereby realizing a comfortable ride. 
     Moreover, a mirror or a half mirror is equipped for changing a direction of an optical path, the number of laser radiators may become fewer than the number of optical paths, thereby reducing cost. 
     Further, since a vertical position of the movable unit is detected by using two optical paths that are not parallel to one another, a vertical position of the movable unit may be detected accurately with no contact. 
     Various modifications and variations are possible in light of the above teachings. Therefore, it is to be understood that within the scope of the appended claims, the present invention may be practiced otherwise than as specifically described herein.