Balance exercise machine

1. A balance exercise machine comprising:

a seat on which a trainee sits;

a swing mechanism that swings the seat with a swing motion in an anteroposterior direction and a swing motion in a widthwise direction;

a controller that controls the swing mechanism, wherein

moving speed in the swing motion of the seat in the anteroposterior direction is twice as fast than that in the widthwise direction; and

origin of the swing motion of the seat in the widthwise direction is set from a position discrepant within a quarter-cycle or a half-cycle from origin of the swing motion of the seat in the anteroposterior direction to a position coinciding with the origin of the swing motion of the seat in the anteroposterior direction;

an extendable and contractible mechanism that varies a distance between the seat and the swing mechanism by extension or contraction thereof so as to vary a stroke of a swing motion of the seat, wherein

said controller further controls the extendable and contractible mechanism;

a supporting unit that supports the swing mechanism rotatably around a predetermined rotation axis;

a pedestal that is to be established on a floor and supports the supporting unit rotatably around a first horizontal axis, and wherein

the extendable and contractible mechanism comprises:

a first inclination mechanism that is provided between the pedestal and the supporting unit, and varies an inclination angle of the rotation axis of the swing mechanism in a vertical plane; and

a second inclination mechanism that is provided between the swing mechanism and the seat, and varies an inclination angle of the seat around a rotation axis of the seat.

2. The balance exercise machine in accordance with claim 1 , wherein

the swing mechanism is comprised of a motor, a first driving gear and a second driving gear which are respectively driven by a driving force of the motor;

the first driving gear has an eccentric shaft which generates a displacement in a first vertical plane including an anteroposterior direction of the balance exercise machine and a vertical direction, and thereby, the seat is swung in the first vertical plane; and

the second driving gear has an eccentric shaft which generates a displacement in a second vertical plane including a widthwise direction of the balance exercise machine and the vertical direction, and thereby, the seat is swung in the second vertical plane.

3. The balance exercise machine in accordance with claim 2 , wherein

the gear ratio of the first driving gear to the second driving gear is set to 1:2; and

the phase 0° of the eccentric shaft of the second driving gear is discrepant from the phase 0° of the eccentric shaft of the first driving gear within a minus quarter-cycle or coinciding with each other.

4. The balance exercise machine in accordance with claim 2 , wherein

the swing mechanism has a mechanism to convert the displacement in the first vertical plane to a movement of the seat to trace an elliptic orbit.

5. The balance exercise machine in accordance with claim 2 , wherein

the controller varies a rotation speed of the motor slower while the seat is lifted up relative to the rotation speed while the seat is lifted up in a continuous swing motion.

6. The balance exercise machine in accordance with claim 1 , wherein

the controller controls to drive the first inclination mechanism and the second inclination mechanism in conjunction with each other to compensate at least a part of inclination of the seat due to extension or contraction of the first inclination mechanism by extension or contraction of the second inclination mechanism.

7. The balance exercise machine in accordance with claim 1 , wherein

the controller controls to drive the first inclination mechanism to vary the inclination angle of the rotation axis of the swing mechanism in a range from substantially horizontal to substantially vertical.

8. The balance exercise machine in accordance with claim 1 , wherein

the controller controls to drive the first inclination mechanism and the second inclination mechanism in conjunction with each other to vary the inclination angle of the rotation axis of the swing mechanism so as to vary the swing motion of the seat between a swing motion around a horizontal axis and a swing motion around a vertical axis with compensating at least a part of inclination of the seat due to extension or contraction of the first inclination mechanism by extension or contraction of the second inclination mechanism.

9. The balance exercise machine in accordance with claim 1 , further comprising:

an offset mechanism that offsets the swing mechanism around the rotation axis.

10. The balance exercise machine in accordance with claim 1 , wherein

the origin of the swing motion of the seat in the widthwise direction coincides (0 degree) with the origin of the swing motion of the seat in the anteroposterior direction so that the center of the seat traces an orbit of a figure of infinity symbol, which is traced from inside to outside.

11. The balance exercise machine in accordance with claim 1 , wherein

the origin of the swing motion of the seat in the widthwise direction is discrepant a half-cycle (180 degrees) from the origin of the swing motion of the seat in the anteroposterior direction so that the center of the seat traces an orbit of a figure of infinity symbol, which is traced from outside of inside.

12. The balance exercise machine in accordance with claim 1 , wherein

the origin of the swing motion of the seat in the widthwise direction is discrepant a quarter-cycle (90 degrees) from the origin of the swing motion of the seat in the anteroposterior direction so that the center of the seat traces an orbit of a figure of reverse V-shape.

13. The balance exercise machine in accordance with claim 1 , wherein

the origin of the swing motion of the seat in the widthwise direction is discrepant a minus quarter-cycle (90 degrees) from the origin of the swing motion of the seat in the anteroposterior direction so that the center of the seat traces an orbit of a figure of V-shape.