Abstract:
A moving system includes an oscillation portion and a conversion portion. The oscillation portion causes oscillation in accordance with a natural frequency by repeating expansion and contraction. The conversion portion converts the oscillation of the oscillation portion into rectilinear movement in one direction. A moving method is also disclosed.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a moving system which converts the oscillation of an oscillator into a thrust for rectilinear movement and a moving method therefor.  
           [0002]    Current moving systems normally use the rotational movement of a power component such as a motor as a thrust for movement.  
           [0003]    However, size reduction of electronic devices is now rapidly progressing, and it is difficult for a device to incorporate a complex power component such as a motor. Simplification and size reduction of moving systems are problems to be solved.  
         SUMMARY OF THE INVENTION  
         [0004]    It is an object of the present invention to provide a simple and compact moving system and a moving method therefor.  
           [0005]    In order to achieve the above object, according to the present invention, there is provided a moving system comprising oscillation means for causing oscillation in accordance with a natural frequency by repeating expansion and contraction, and conversion means for converting oscillation of the oscillation means into rectilinear movement in one direction. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    [0006]FIGS. 1A to  1 D are side views for explaining the arrangement and operation of a moving system according to the first embodiment of the present invention;  
         [0007]    [0007]FIGS. 2A and 2B are plan and side views, respectively, of a moving system according to the second embodiment of the present invention;  
         [0008]    [0008]FIGS. 3A to  3 D are plan views for explaining the operation of the moving system shown in FIGS. 2A and 2B;  
         [0009]    [0009]FIG. 4 is a side view of a moving system according to the third embodiment of the present invention;  
         [0010]    [0010]FIGS. 5A to  5 D are side views for explaining the operation of the moving system shown in FIG. 4;  
         [0011]    [0011]FIGS. 6A and 6B are side views for explaining the arrangement and operation of a moving system according to the fourth embodiment of the present invention;  
         [0012]    [0012]FIGS. 7A and 7B are plan and side views, respectively, showing the arrangement of a moving system according to the fifth embodiment of the present invention;  
         [0013]    [0013]FIGS. 8A to  8 C are plan views for explaining the operation of the moving system shown in FIGS.  7 A and  7 B; and  
         [0014]    [0014]FIGS. 9A to  9 D are plan views for explaining the arrangement and operation of a moving system according to the sixth embodiment of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0015]    The present invention will be described below in detail with reference to the accompanying drawings.  
         [0016]    A moving system according to the first embodiment of the present invention will be described with reference to FIGS. 1A to  1 D. FIG. 1A shows a moving system  1  which is set in an equilibrium state without expansion of a spring  2  and arranged on a solid surface  8 . The moving system  1  according to this embodiment has the expandable spring  2  having a natural frequency and drag adjusting units  3 A and  3 B fixed to the two ends of the spring  2 , as shown in FIG. 1A.  
         [0017]    The drag adjusting units  3 A and  3 B comprise plate-shaped supports  4 A and  4 B horizontally placed, and hemispherical bodies  5 A and  5 B attached to the supports  4 A and  4 B through direction control plates  6 A and  6 B, respectively. Small casters  7 A and  7 B are attached to the lower surfaces of the supports  4 A and  4 B. The casters  7 A and  7 B reduce the friction between the moving system  1  and the solid surface  8  when the moving system  1  moves on the solid surface  8 . The moving system  1  moves in a medium  9  made of a fluid such as a liquid or/and a gas, which fill the space on the solid surface  8 . The barycenter of the moving system  1  is located almost at the center of the spring  2 .  
         [0018]    The hemispherical bodies  5 A and  5 B have cavities inside and openings  15 A and  15 B that are open to the medium  9 . The hemispherical body  5 A has inner and outer surfaces  10 A and  11 A. The hemispherical body  5 B has inner and outer surfaces  10 B and  11 B. The direction control plates  6 A and  6 B can rotate on the supports  4 A and  4 B. When the direction control plates  6 A and  6 B rotate by 180°, the opening directions of the openings  15 A and  15 B of the hemispherical bodies  5 A and  5 B are reversed.  
         [0019]    The operation of the moving system  1  when the openings  15 A and  15 B of the hemispherical bodies  5 A and  5 B are directed in a direction C (from the drag adjusting unit  3 A to the drag adjusting unit  3 B) will be described next.  
         [0020]    In the moving system  1  set in the equilibrium state, when forces F are applied to the outer ends of the supports  4 A and  4 B such that the drag adjusting units  3 A and  3 B come close to each other, the spring  2  contracts, as shown in FIG. 1B. When the spring  2  contracts, the hemispherical body  5 A receives, on its inner surface  10 A, stress from the medium  9  through the opening  15 A. Hence, the drag force from the medium  9  against the movement of the drag adjusting unit  3 A in the direction C is large. On the other hand, the hemispherical body  5 B only receives, on its outer surface  11 B, stress from the medium  9  when the spring  2  contracts. Hence, the drag force from the medium  9  against the movement of the drag adjusting unit  3 B in a direction D (from the drag adjusting unit  3 B to the drag adjusting unit  3 A) is small. For this reason, the moving distance of the drag adjusting unit  3 A in the direction C is shorter than that of the drag adjusting unit  3 B in the direction D. Accordingly, the barycenter of the moving system  1  moves in the direction D.  
         [0021]    In this state, when the forces F at the outer ends of the supports  4 A and  4 B are canceled, the spring  2  expands, as shown in FIG. 1C. When the spring  2  expands, the hemispherical body  5 A receives, on its outer surface  11 A, stress only from the medium  9 . Hence, the drag force from the medium  9  against the movement of the drag adjusting unit  3 A in the direction D is small. On the other hand, the hemispherical body  5 B receives, on its inner surface  10 B, stress from the medium  9  through the opening  15 B. Hence, the drag force from the medium  9  against the movement of the drag adjusting unit  3 B in the direction C is large. For this reason, the moving distance of the drag adjusting unit  3 A in the direction D when the forces F are canceled is longer than that of the drag adjusting unit  3 B in the direction C. Accordingly, the barycenter of the moving system  1  moves in the direction D.  
         [0022]    Next, the spring  2  contracts in accordance with its natural frequency, as shown in FIG. 1D. When the spring  2  contracts, the hemispherical body  5 A receives, on its inner surface  10 A, stress from the medium  9  through the opening  15 A. Hence, the drag force from the medium  9  against the movement of the drag adjusting unit  3 A in the direction C is large. On the other hand, the hemispherical body  5 B only receives, on its outer surface  11 B, stress from the medium  9 . Hence, the drag force from the medium  9  against the movement of the drag adjusting unit  3 B in the direction D is small. For this reason, the moving distance of the drag adjusting unit  3 A in the direction D is shorter than that of the drag adjusting unit  3 B in the direction C. Accordingly, the barycenter of the moving system  1  moves in the direction D.  
         [0023]    Next, the spring  2  expands in accordance with its natural frequency. When the spring  2  expands, the drag adjusting unit  3 A largely moves in the direction D while the drag adjusting unit  3 B slightly moves in the direction C, as in FIG. 1C. Hence, the barycenter of the moving system  1  moves in the direction D.  
         [0024]    Every time the spring  2  contracts/expands in accordance with its natural frequency, the barycenter of the moving system  1  always moves in the direction D. The entire moving system  1  moves in the direction in which the outer surfaces  11 A and  11 B of the drag adjusting units  3 A and  3 B are directed. The movement of the moving system  1  continues until the external force F is consumed as heat by the friction generated between the moving system  1  and the medium  9  by contraction/expansion of the spring  2 .  
         [0025]    When the direction control plates  6 A and  6 B are rotated by 180°, the openings  15 A and  15 B are directed in the direction D. This is equivalent to 180° rotation of the entire moving system  1 . In this case, the moving system  1  moves in the direction C, as is apparent from the above description. According to the first embodiment, the drag adjusting units  3 A and  3 B convert the oscillation of the spring  2  into rectilinear movement.  
         [0026]    A moving system according to the second embodiment of the present invention will be described with reference to FIGS. 2A and 2B.  
         [0027]    As shown in FIG. 2A, a moving system  101  according to this embodiment has a spring  102  and drag adjusting units  103 A and  103 B fixed to the two ends of the spring  102 . The drag adjusting units  103 A and  103 B comprise thick plate-shaped supports  104 A and  104 B each of which is vertically placed such that the two surfaces become parallel to the moving direction, and pairs of plate-shaped bodies  105 A and  105 B attached to the D-direction ends of the both surfaces of the supports  104 A and  104 B through hinges  106 A and  106 B, respectively. The pairs of hinges  106 A and  106 B can open within the range of an angle α to 90°. The angle α can take any value as long as it is smaller than 90°, though the angle α is preferably about 2° to 30°. The plate-shaped bodies  105 A and  105 B are fixed to the hinges  106 A and  106 B. Hence, the angle made by the pair of plate-shaped bodies  105 A or the pair of plate-shaped bodies  105 B ranges from the minimum angle 2α to the maximum angle of 180°. In an equilibrium state without expansion of the spring, both the pair of plate-shaped bodies  105 A and the pair of plate-shaped bodies  105 B make the angle 2α or an arbitrary angle. The pairs of plate-shaped bodies  105 A and  105 B open in the same direction.  
         [0028]    Small casters  107 A and  107 B are attached to the lower ends of the supports  104 A and  104 B, as shown in FIG. 2B. The casters  107 A and  107 B reduce the friction between the moving system  101  and a solid surface  108  when the moving system  101  moves on the solid surface  108 . The moving system  101  moves in a medium  109  made of a fluid such as a liquid or/and a gas, which fill the space on the solid surface  108 .  
         [0029]    [0029]FIG. 3A shows the moving system  1  which is set in the equilibrium state without expansion of the spring  102  and arranged in the medium  109 . Referring to FIG. 3A, each of the plate-shaped bodies  105 A has inner and outer surfaces  110 A and  111 A. Each of the plate-shaped bodies  105 B has inner and outer surfaces  110 B and  111 B. The plate-shaped bodies  105 A and  105 B make an angle close to the minimum angle 2α. The barycenter of the moving system  101  is located almost at the center of the spring  102 .  
         [0030]    When forces F are applied to the outer ends of the supports  104 A and  104 B of the moving system  101  in the equilibrium state such that the drag adjusting units  103 A and  103 B come close to each other, the spring  102  contracts, as shown in FIG. 3B. As the spring  102  contracts, the plate-shaped bodies  105 A open to the maximum angle of 180° upon receiving, on their inner surfaces  110 A, stress from the medium  109 . On the other hand, the plate-shaped bodies  105 B close to the minimum angle 2α upon receiving, on their outer surfaces  111 B, stress from the medium  109  as the spring  102  contracts. In this case, the plate-shaped bodies  105 A open up to the maximum angle of 180° and therefore receive a large force from the medium  109 . The plate-shaped bodies  105 B close to the minimum angle 2α and therefore receive a small force from the medium  109 . Hence, the moving distance of the drag adjusting unit  103 A in a direction C when the forces F are applied is shorter than that of the drag adjusting unit  103 B in the direction D. For this reason, the barycenter of the moving system  101  moves in the direction D.  
         [0031]    In this state, when the forces F are canceled, the spring  102  expands. As the spring  2  expands, the plate-shaped bodies  105 A close to the minimum angle 2α upon receiving, on their outer surfaces  111 A, stress from the medium  109 . On the other hand, the plate-shaped bodies  105 B open to the maximum angle of 180° upon receiving, on their inner surfaces  110 B, stress from the medium  109  as the spring  102  expands. In this case, the plate-shaped bodies  105 A close to the minimum angle 2α and therefore receive a small force from the medium  109 . The plate-shaped bodies  105 B open to the maximum angle of 180° and therefore receive a large force from the medium  109 . Hence, the moving distance of the drag adjusting unit  103 A in the direction D when the forces F are canceled is longer than that of the drag adjusting unit  103 B in the direction C. For this reason, the barycenter of the moving system  1  moves in the direction D.  
         [0032]    Next, the spring  102  contracts in accordance with its natural frequency, as shown in FIG. 3D. As the spring  102  contracts, the plate-shaped bodies  105 A open to the maximum angle of 180° upon receiving, on their inner surfaces  110 A, stress from the medium  109 . On the other hand, the plate-shaped bodies  105 B close to the minimum angle 2α upon receiving, on their outer surfaces  111 B, stress from the medium  109  as the spring  102  contracts. In this case, the plate-shaped bodies  105 A open up to the maximum angle of 180° and therefore receive a large force from the medium  109 . The plate-shaped bodies  105 B close to the minimum angle 2α and therefore receive a small force from the medium  109 . Hence, the moving distance of the drag adjusting unit  103 A in the direction C is shorter than that of the drag adjusting unit  103 B in the direction D. For this reason, the barycenter of the moving system  101  moves in the direction D.  
         [0033]    Next, the spring  102  expands in accordance with its natural frequency. When the spring  102  expands, the drag adjusting unit  103 A largely moves in the direction D while the drag adjusting unit  103 B slightly moves in the direction C, as in FIG. 3C. For this reason, the barycenter of the moving system  101  moves in the direction D.  
         [0034]    The spring  102  repeatedly contracts/expands in accordance with its natural frequency. At this time, since the barycenter of the moving system  101  always moves in the direction D, the entire moving system  101  moves in the direction D. The movement of the moving system  101  continues until the external force F is consumed as heat by the friction generated between the moving system  101  and the medium by contraction/expansion of the spring  102 .  
         [0035]    In the above description, the opening angle of the hinges  106 A and  106 B ranges from α to 90° such that the plate-shaped bodies  105 A and  105 B open in only one of the moving directions. However, the plate-shaped bodies  105 A and  105 B may open in both of the moving directions. More specifically, when the opening angle of the hinges  106 A and  106 B is set in two steps, i.e., from α to 90° and from 90° to ( 180°-α ), the moving system  101  on the solid surface  108  can also move in the direction C.  
         [0036]    As described above, in the second embodiment as well, the drag adjusting units  103 A and  103 B convert the oscillation of the spring  102  into rectilinear movement, as in the first embodiment. In the second embodiment, additionally, each drag adjusting unit has a means for changing the drag force from the medium while the spring expands/contracts. For this reason, the moving distance ratio between the two drag adjusting units can be made higher than that in the first embodiment.  
         [0037]    In the above-described first and second embodiments, the moving system moves on the solid surface. However, the present invention is not limited to this. For example, when the specific gravity of the entire moving system is designed to be equal to that of the medium, the moving system can move from an arbitrary point in the medium in an arbitrary direction.  
         [0038]    A moving system according to the third embodiment of the present invention will be described next with reference to FIG. 4.  
         [0039]    A moving system  201  according to this embodiment has a spring  202  and friction adjusting units  203 A and  203 B fixed to the two ends of the spring  202 , as shown in FIG. 4. The friction adjusting units  203 A and  203 B have supports  204 A and  204 B each having an L shape when viewed from a side, circular-saw-shaped wheels  212 A and  212 B rotatably supported by the supports  204 A and  204 B, and L-shaped plate-shaped bodies  205 A and  205 B pivotally supported by the supports  204 A and  204 B by pins  206 A and  206 B, respectively.  
         [0040]    The supports  204 A and  204 B are constituted by horizontal portions which support the wheels  212 A and  212 B at the C-direction end portions, and vertical portions which have upper end portions connected to the D-direction end portions of the supports  204 A and  204 B and small casters  207 A and  207 B attached to the lower surfaces of the lower end portions. The plate-shaped bodies  205 A and  205 B are constituted by arm portions supported by the pins  206 A and  206 B and brake portions connected to the arm portions at an angle of 90°.  
         [0041]    In an equilibrium state without expansion of the spring  202 , the distal ends of the arm portions of the plate-shaped bodies  205 A and  205 B are inserted into serrate portions  213 A and  213 B of the wheels  212 A and  212 B. When the wheels  212 A and  212 B rotate clockwise, the distal end portions of the arm portions of the plate-shaped bodies  205 A and  205 B are pressed downward by the back surfaces of the serrate portions  213 A and  213 B, and the distal end portions of the brake portions of the plate-shaped bodies  205 A and  205 B are separated from a solid surface  208 . On the other hand, when the wheels  212 A and  212 B rotate counterclockwise, the distal ends of serrate portions  213 A and  213 B press the distal ends of the arm portions of the plate-shaped bodies  205 A and  205 B upward. For this reason, the brake portions of the plate-shaped bodies  205 A and  205 B move downward to bring their distal ends into contact with the solid surface  208  to press the solid surface  208 .  
         [0042]    [0042]FIG. 5A shows the moving system  201  which is set in the equilibrium state without expansion of the spring  202  and arranged on the solid surface  208 . The barycenter of the moving system  201  is located almost at the center of the spring  202 . Referring to FIGS. 5A to  5 D, the serrate portions  213 A and  213 B of the wheels  212 A and  212 B are represented by circumscribed circles of alternate long and short dashed lines.  
         [0043]    Forces F are applied to the outer ends of the supports  204 A and  204 B of the moving system  201  in the equilibrium state such that the friction adjusting units  203 A and  203 B come close to each other. When the spring  202  contracts due to the applied forces F, the wheel  212 A is going to rotate counterclockwise. However, as soon as the wheel  212 A rotates, the brake portion of the plate-shaped body  205 A is strongly pressed against the solid surface  208 . On the other hand, the wheel  212 B rotates clockwise. The brake portion of the plate-shaped body  205 B is separated from the solid surface  208 . When the brake portion of the plate-shaped body  205 A is strongly pressed against the solid surface  208 , a large frictional force acts between the solid surface  208  and the brake portion of the plate-shaped body  205 A. On the other hand, no frictional force acts between the plate-shaped body  205 B and the solid surface  208  because the brake portion of the plate-shaped body  205 A is separated from the solid surface  208 . Hence, the friction adjusting unit  203 A slightly moves in the direction C while the friction adjusting unit  203 B largely moves in the direction D. For this reason, the barycenter of the moving system  201  moves in the direction D.  
         [0044]    In this state, when the forces F are canceled, the spring  202  expands. When the spring  202  expands, the wheel  212 A rotates clockwise to separate the brake portion of the plate-shaped body  205 A from the solid surface  208 , as shown in FIG. 5C. On the other hand, when the spring  202  expands, the wheel  212 B is going to rotate counterclockwise. However, as soon as the wheel  212 B rotates, the brake portion of the plate-shaped body  205 B is strongly pressed against the solid surface  208 . On the other hand, since the brake portion of the plate-shaped body  205 A is separated from the solid surface  208 , no frictional force acts between the plate-shaped body  205 A and the solid surface  208 . Since the brake portion of the plate-shaped body  205 B is strongly pressed against the solid surface  208 , a strong frictional force acts between the plate-shaped body  205 B and the solid surface  208 . Hence, when the forces F are canceled, the friction adjusting unit  203 A largely moves in the direction D while the friction adjusting unit  203 B slightly moves in the direction C. For this reason, the barycenter of the moving system  201  moves in the direction D.  
         [0045]    Next, the spring  202  contracts in accordance with its natural frequency, as shown in FIG. 5D. When the spring  202  contracts, the wheel  212 A is going to rotate counterclockwise. However, as soon as the wheel  212 A rotates, the brake portion of the plate-shaped body  205 A is strongly pressed against the solid surface  208 . On the other hand, when the spring  202  contracts, the wheel  212 B rotates clockwise. The brake portion of the plate-shaped body  205 B is separated from the solid surface  208 . Since the brake portion of the plate-shaped body  205 A is strongly pressed against the solid surface  208 , a large frictional force acts between the plate-shaped body  205 A and the solid surface  208 . Since the brake portion of the plate-shaped body  205 B is separated from the solid surface  208 , no frictional force acts between the plate-shaped body  205 B and the solid surface  208 . Hence, the friction adjusting unit  203 A slightly moves in the direction C while the friction adjusting unit  203 B largely moves in the direction D. For this reason, the barycenter of the moving system  201  moves in the direction D.  
         [0046]    Next, the spring  202  expands in accordance with its natural frequency. When the spring  202  expands, the friction adjusting unit  203 A largely moves in the direction D while the friction adjusting unit  203 B slightly moves in the direction C, as in FIG. 5C. For this reason, the barycenter of the moving system  201  moves in the direction D.  
         [0047]    The spring  202  repeatedly contracts/expands in accordance with its natural frequency. At this time, since the barycenter of the moving system  201  always moves in the direction D, the entire moving system  201  moves in the direction D. The movement of the moving system  201  continues until the external force F is consumed as heat by the friction generated between the friction adjusting units and the solid surface.  
         [0048]    In the above description, the plate-shaped bodies  205 A and  205 B serving as brake members are mechanically separated from or pressed against the solid surface  208 . However, the present invention is not limited to this. For example, sensors for detecting the rotational directions of the wheels  212 A and  212 B may be attached. The plate-shaped bodies  205 A and  205 B may be separated from or pressed against the solid surface  208  by electrically driving the plate-shaped bodies  205 A and  105 B in the vertical direction on the basis of signals from the sensors.  
         [0049]    As described above, in the moving system according to the third embodiment has an effect for converting the oscillation of the spring into rectilinear movement, as in the first and second embodiments. In the first to third embodiments, the force F need not always be mechanically applied but may be magnetically or electrically applied. For example, a force of magnetic flux may be applied to a support made of a magnetic material. Alternatively, a force of electric field may be applied to a charged support.  
         [0050]    A moving system according to the fourth embodiment of the present invention will be described next with reference to FIGS. 6A and 6B.  
         [0051]    [0051]FIG. 6A shows a moving system  301  which is set in an equilibrium state without expansion of springs  302  and arranged on a solid surface  308 . The moving system  301  according to this embodiment has the pair of springs  302  arranged in parallel and drag adjusting units  303 A and  303 B fixed to the two ends of each spring  302 , as shown in FIG. 6A. The drag adjusting unit  303 A has a plunger  316  and a hemispherical body  305 A attached to the plunger  316  through a direction control plate  306 A. The drag adjusting unit  303 B has an electromagnet  317  and a hemispherical body  305 B attached to the electromagnet  317  through a direction control plate  306 B.  
         [0052]    Small casters  307 A and  307 B are attached to the lower ends of the plunger  316  and electromagnet  317 , as in the first embodiment. A strain gauge  318  is attached to one of the springs  302 . The output signal from the strain gauge  318  is amplified by an amplifier  319  and supplied to the coil of the electromagnet  317 . Parts except the hemispherical bodies and casters of the moving system  301  are shielded from a medium  309  by a shielding member (housing) (not shown). The barycenter of the moving system  301  is located almost at the center of the spring  302 .  
         [0053]    The hemispherical bodies  305 A and  305 B have the same shape as that of the hemispherical bodies  5 A and  5 B of the first embodiment. When the direction control plates  306 A and  306 B are rotated, the opening directions of openings  315 A and  315 B can be changed. The operation of the moving system of this embodiment when the openings  315 A and  315 B of the hemispherical bodies  305 A and  305 B are directed in a direction C will be described.  
         [0054]    When a trigger signal is supplied from a trigger circuit (not shown) to the coil of the electromagnet  317  of the moving system  301  in the equilibrium state, the springs  302  start oscillating in accordance with the natural frequency of the moving system  301 . When the springs  302  start oscillating, a signal having the oscillation period of the springs  302  is output from the strain gauge  318  attached to the spring  302  to the amplifier  319 . The amplifier  319  amplifies the signal and supplies a current pulse having a predetermined amplitude to the coil of the electromagnet  317 . Since the period of the current pulse matches the period of the natural frequency of the moving system  301 , self-excited oscillation is induced in the spring  302 .  
         [0055]    When the spring  302  contracts, the hemispherical body  305 A receives, on its inner surface  310 A, stress from the medium  309  through the opening  315 A, as shown in FIG. 6B. Hence, the drag force from the medium  309  against the movement of the drag adjusting unit  303 A in the direction C is large. On the other hand, the hemispherical body  305 B only receives, on its outer surface  311 B, stress from the medium  309  when the spring  302  contracts. Hence, the drag force from the medium  309  against the movement of the drag adjusting unit  303 B in a direction D is small. For this reason, the moving distance of the drag adjusting unit  303 A in the direction C is shorter than that of the drag adjusting unit  303 B in the direction D. Accordingly, the barycenter of the moving system  301  moves in the direction D.  
         [0056]    Subsequently, as in the first embodiment, when the spring  302  repeatedly expands/contracts in accordance with the natural frequency, the moving system moves in the direction D. In the first embodiment, the movement of the moving system stops due to the friction generated between the moving system and the medium. In the fourth embodiment, however, the moving system continuously moves as far as the current pulse is supplied to the coil of the electromagnet  317 .  
         [0057]    When the direction control plates  306 A and  306 B are rotated, the moving direction of the moving system  301  is reversed, as in the first embodiment. In the above description, a strain gauge is used to detect the oscillation period of the spring  302 . Instead of the strain gauge, any other device such as a piezoelectric element or photodetector capable of detecting the oscillation period or displacement amount can be used.  
         [0058]    A moving system according to the fifth embodiment of the present invention will be described next with reference to FIGS. 7A and 7B.  
         [0059]    A moving system  401  according to this embodiment has springs  402  and drag adjusting units  403 A and  403 B, as shown in FIG. 7A. The drag adjusting units  403 A and  403 B have supports  404 A and  404 B and plate-shaped bodies  405 A and  405 B attached to the supports  404 A and  404 B through hinges  406 A and  406 B. The supports  404 A and  404 B and plate-shaped bodies  405 A and  405 B have the same arrangements as in the embodiment shown in FIGS. 2A and 2B, and a description thereof will be omitted.  
         [0060]    The support  404 A is fixed on a plunger  416  to which small casters  407 A are attached, as shown in FIG. 7B. The support  404 B is fixed on an electromagnet  417  to which small casters  407 B are attached. One end of each spring  402  is connected to the electromagnet  417 . The other end of each spring  402  is connected to the plunger  416 . When a current flows to the coil of the electromagnet  417 , an attracting force is generated between the electromagnet  417  and the plunger  416 . Parts except the plate-shaped bodies, supports, and casters of the moving system  401  are shielded from a medium  409  by a shielding member (housing) (not shown).  
         [0061]    [0061]FIG. 8A shows the moving system  401  which is set in an equilibrium state without expansion of the springs  402  and arranged in the medium  409 . Referring to FIG. 8A, each of the plate-shaped bodies  405 A has inner and outer surfaces  410 A and  411 A. Each of the plate-shaped bodies  405 B has inner and outer surfaces  410 B and  411 B. The plate-shaped bodies  405 A and  405 B make an angle close to a minimum angle 2α. The barycenter of the moving system  401  is located almost at the center of the spring  402 .  
         [0062]    When a predetermined current is supplied to the coil of the electromagnet on which the support  404 B of the moving system  401  in the equilibrium state is installed, the springs  402  contract. When the springs  402  contract, the plate-shaped bodies  405 A open to the maximum angle of 180° upon receiving, on their inner surfaces  410 A, stress from the medium  409 , as shown in FIG. 8B. Hence, the movement of the drag adjusting unit  403 A in the direction C immediately stops. On the other hand, as the springs  402  contract, the plate-shaped bodies  405 B close so the drag received from the medium  409  decreases. More specifically, as the springs  402  contract, the drag received from the medium  409  gradually decreases. Since the contraction of the springs  402  is accelerated, the drag adjusting unit  403 B abruptly moves in the direction D. When the drag adjusting unit  403 B abruptly moves in the direction D, the springs  402  start expanding due to the repelling force of the springs  402 .  
         [0063]    When the springs  402  expand, the plate-shaped bodies  405 B open to the maximum angle of 180° upon receiving, on their inner surfaces  410 B, stress from the medium  409 , as shown in FIG. 8C. Hence, the movement of the drag adjusting unit  403 B in the direction C immediately stops. On the other hand, as the springs  402  expand, the plate-shaped bodies  405 A close so the drag received from the medium  409  gradually decreases. More specifically, as the springs  402  expand, the drag received from the medium  409  decreases. Since the expansion of the springs  402  is accelerated, the drag adjusting unit  403 A abruptly moves in the direction D. When the drag adjusting unit  403 A abruptly moves in the direction D, the springs  402  start contracting.  
         [0064]    Subsequently, as in the fourth embodiment, when the springs  402  repeatedly expand/contract in accordance with the natural frequency, the moving system moves in the direction D. In the fifth embodiment, when an energy is supplied from the magnetic field of the electromagnet  417 , the amplitude of the oscillation of the spring  402  exhibits a so-called limit cycle. The fifth embodiment is a modification to the second embodiment in which the oscillation of the spring exhibits a limit cycle. As is apparent, the third embodiment can also be modified such that the oscillation of the spring exhibits a limit cycle.  
         [0065]    The spring need not always be oscillated by the magnetic means but may be oscillated by an electrical or/and mechanical means.  
         [0066]    A moving system according to the sixth embodiment of the present invention will be described next with reference to FIGS. 9A to  9 D.  
         [0067]    A moving system  501  according to this embodiment has a cluster molecule having cores  514 A and  514 B, side chain portions  505 A 1  and  505 A 2  arranged on a D-direction side of the core  514 A, and side chain portions  505 B 1  and  505 B 2  arranged on a C-direction side of the core  514 B, as shown in FIG. 9A. Each of the cores  514 A and  514 B and side chain portions  505 A 1 ,  505 A 2 ,  505 B 1 , and  505 B 2  may be formed from either a single atom or a plurality of atoms. Each of the side chain portions  505 A 1 ,  505 A 2 ,  505 B 1 , and  505 B 2  may form one side chain or part of a side chain.  
         [0068]    According to the quantum mechanics and solid state theory, oscillation occurs between the cores  514 A and  514 B. Similarly, oscillation also occurs between the side chain portions  505 A 1  and  505 A 2 , between the side chain portions  505 B 1  and  505 B 2 , between the core  514 A and the side chain portions  505 A 1  and  505 A 2 , and between the core  514 B and the side chain portions  505 B 1  and  505 B 2 .  
         [0069]    In this embodiment, the cluster molecule has such an oscillation phase that when the space between the cores  514 A and  514 B contracts, the space between the side chain portions  505 A 1  and  505 A 2  and the space between the core  514 A and the side chain portions  505 A 1  and  505 A 2  expand, and the space between side chain portions  505 B 1  and  505 B 2  and the space between the core  514 B and the side chain portions  505 B 1  and  505 B 2  contract. The cluster molecule also has such an oscillation phase that when the space between the cores  514 A and  514 B expands, the space between the side chain portions  505 A 1  and  505 A 2  and the space between the core  514 A and the side chain portions  505 A 1  and  505 A 2  contract, and the space between side chain portions  505 B 1  and  505 B 2  and the space between the core  514 B and the side chain portions  505 B 1  and  505 B 2  expand. The side chain portions  505 A 1  and  505 A 2  serve as a drag adjusting unit  503 A, and the side chain portions  505 B 1  and  505 B 2  serve as a drag adjusting unit  503 B.  
         [0070]    [0070]FIG. 9A shows the positions of the cores  514 A and  514 B and the side chain portions  505 A 1 ,  505 A 2 ,  505 B 1 , and  505 B 2  when the oscillation of the cluster molecule is averaged over time.  
         [0071]    The moving system according to this embodiment may be formed from a single cluster molecule. Alternatively, the moving system may be constituted by an array structure in which one cluster molecule is defined as a fundamental structure, and a plurality of cluster molecules are arranged in an array in the horizontal direction perpendicular to the C-D direction. Adjacent cluster molecules are bonded to each other by the Van der Waals force.  
         [0072]    [0072]FIG. 9B shows a state wherein the space between the cores  514 A and  514 B contracts. As the space between the cores  514 A and  514 B contracts, the space between the core  514 A and the side chain portions  505 A 1  and  505 A 2  expands, and the space between the side chain portions  505 A 1  and  505 A 2  expands. On the other hand, the space between the core  514 B and the side chain portions  505 B 1  and  505 B 2  contracts, and the space between the side chain portions  505 B 1  and  505 B 2  contracts. The side chain portions  505 A 1  and  505 A 2  receive a large drag from a medium  509  because the interval therebetween increases. The side chain portions  505 B 1  and  505 B 2  receive a small drag from the medium  509  because the interval therebetween decreases. Hence, the moving distance of the drag adjusting unit  503 A to the left side of the drawing surface is shorter than that of the drag adjusting unit  503 B to the right side of the drawing surface. For this reason, the barycenter of the moving system  501  moves to the right side of the drawing surface.  
         [0073]    Next, as shown in FIG. 9C, the space between the cores  514 A and  514 B expands. As the space between the cores  514 A and  514 B expands, the space between the core  514 A and the side chain portions  505 A 1  and  505 A 2  contracts, and the space between the side chain portions  505 A 1  and  505 A 2  contracts. On the other hand, the space between the core  514 B and the side chain portions  505 B 1  and  505 B 2  expands, and the space between the side chain portions  505 B 1  and  505 B 2  expands. The side chain portions  505 A 1  and  505 A 2  receive a small drag from the medium  509  because the interval therebetween decreases. The side chain portions  505 B 1  and  505 B 2  receive a large drag from the medium  509  because the interval therebetween increases. Hence, the moving distance of the drag adjusting unit  503 A to the right side of the drawing surface is longer than that of the drag adjusting unit  503 B to the left side of the drawing surface. For this reason, the barycenter of the moving system  501  moves to the right side of the drawing surface.  
         [0074]    Next, as shown in FIG. 9D, the space between the cores  514 A and  514 B contracts. As the space between the cores  514 A and  514 B contracts, the space between the core  514 A and the side chain portions  505 A 1  and  505 A 2  expands, and the space between the side chain portions  505 A 1  and  505 A 2  expands. On the other hand, the space between the core  514 B and the side chain portions  505 B 1  and  505 B 2  contracts, and the space between the side chain portions  505 B 1  and  505 B 2  contracts. The side chain portions  505 A 1  and  505 A 2  receive a large drag from the medium  509  because the interval therebetween increases. The side chain portions  505 B 1  and  505 B 2  receive a small drag from the medium  509  because the interval therebetween decreases. Hence, the moving distance of the drag adjusting unit  503 A to the left side of the drawing surface is shorter than that of the drag adjusting unit  503 B to the right side of the drawing surface. For this reason, the barycenter of the moving system  501  moves to the right side of the drawing surface.  
         [0075]    Next, when the space between the cores  514 A and  514 B expands, the drag adjusting unit  503 A largely moves in the direction D while the drag adjusting unit  503 B slightly moves in the direction C, as in FIG. 9C. For this reason, the barycenter of the moving system  501  moves in the direction D.  
         [0076]    The cluster molecule periodically repeats the above-described contraction/expansion. At this time, since the barycenter of the moving system  501  always moves in the direction D, the entire moving system  501  moves in the direction D. The movement of the moving system  501  continues as far as the cluster molecule continues oscillation.  
         [0077]    As described above, the moving system according to the sixth embodiment converts oscillation into rectilinear movement in each molecule.  
         [0078]    In the above-described embodiments, drag adjusting units or friction adjusting units are connected to the two ends of a spring or two atoms or molecules. However, the present invention is not limited to this. For example, even when a drag adjusting unit or friction adjusting unit is connected to only one end of a spring, and, e.g., a balancer is connected to the other end, the oscillation of the spring is converted into rectilinear movement, although the moving distance becomes shorter than when drag adjusting units are connected to the two ends.  
         [0079]    The present invention has been described above on the basis of the preferred embodiments. The moving system of the present invention is not limited to the above-described embodiments. The present invention also incorporates a moving system for which various changes and modifications are made within the spirit and scope of the invention. For example, the medium in which the moving system moves need not always be a liquid or gas but may be particles or a gel material. The medium is not limited to a specific medium as long as it is a fluid. In addition, the plate-shaped body or hemispherical body that forms a drag adjusting unit may be exchanged with any other body such as a rectangular parallelepiped or a rotating cone as long as it has a shape for receiving a drag force that changes between the contraction mode and expansion mode of the spring. Furthermore, the spring may be exchanged with any other elastic body that oscillates.  
         [0080]    As has been described above, according to the present invention, the oscillation of an internal oscillation portion is converted into rectilinear movement through drag adjusting units or friction adjusting units provided at the two ends of the oscillation portion. Hence, the moving system can move in one direction without using any complex power component such as a motor.  
         [0081]    In addition, since the drag forces or frictional forces that the two ends of the oscillation portion receive from the medium or solid surface are increased/decreased in reverse directions when the oscillation portion expands/contracts, the moving system can be moved in one direction.