The present disclosure relates to a motion base for shaking a placement subject such as a person or a seat. More specifically, the present disclosure relates to a motion base in which (i) a first installation base and a first movable base on which the placement subject is to be placed are connected to each other by a first actuator able to extend and contract and (ii) a spherical surface body constituting a perfect sphere or a portion of the sphere is interposed between the first installation base and the first movable base, thereby enabling a reduction in an output of the first actuator able to extend and contract when the first movable base is shaken relative to the first installation base.
Conventionally offered motion bases for shaking a placement subject such as a person or a seat include a Stewart platform in which six extendable and contractible actuators are connected to three portions of an installation base and three portions of a movable base in the shape of the letter āVā. In such a motion base, the actuators are turnably connected to the installation base and/or the movable base (that is, such that, in the portions where the actuators are coupled with each of the above-described bases, each of the actuators has a rotational degree of freedom relative to its connecting partner). This motion base enables achievement of (i) three-degrees-of-freedom translational motions in the forward-backward, vertical, and leftward-rightward directions of the movable base and (ii) three-degrees-of-freedom turning motions around a roll axis, a pitch axis and a yaw axis.
However, this motion base requires complicated coordinate transformation processing for control of extension or contraction of the actuator. Additionally, if the center of gravity is located at the upper portion of the movable base on which the placement subject is placed, a moment increases due to a turning motion, and thus this motion base requires a high-power actuator that can withstand the increasing moment.
Other conventionally-offered configurations of such a motion base include a configuration in which (i) the installation base and the movable base are vertically connected to each other by an extendable and contractible actuator and (ii) their connecting portions are fitted with the connecting portions having a rotational degree of freedom, thereby enabling achievement of one-degree-of-freedom translational motion in the vertical direction and two-degrees-of-freedom turning motions around the roll axis and the pitch axis. As in the Stewart platform, in a motion base having such a configuration, when the center of gravity is located at the upper portion of the movable base on which the placement subject is placed, a moment increases due to a turning motion, and thus the motion base having such a configuration also requires a high-power actuator that can withstand the increasing moment.
Additionally, the other conventionally-offered configurations of such a motion base also include a configuration in which an extendable and contractible column is interposed between the installation base and the movable base of the Stewart platform, thereby dissipating, to the installation base, most of the weight received by the movable base (refer to Patent Literature 1). In this motion base, a load applied during a forward-backward or leftward-rightward translational motion is reduced by a reaction force caused by connecting the column and the installation base via an elastic member such as a rubber cord. In the motion base having such a configuration, the column and the movable base are connected with each other by a fastening rope, thereby enabling, by the reaction force, a reduction of the moment that increases during the turning motion around the roll axis, the pitch axis, and the yaw axis.
Other literature also disclose that a motion base can reduce a moment that increases during a turning motion (refer to Patent Literature 2 and 3).
Patent Literature 1: National Patent Publication No. 2016-533534
Patent Literature 2: Japanese Patent No. 3795838
Patent Literature 3: Japanese Patent No. 4813038
The motion base disclosed in a document represented by Patent Literature 1 described above requires use of an elastic member such as a coil spring or a fastening rope in order to reduce the moment that increases during the turning motion. Additionally, if the placement subject is light, the movable base is hard to rotate unless the reaction force is adjusted in accordance with the weight of the placement subject or the position of the center of gravity of the placement subject. As a result, the motion base requires dynamic control of a position at which the members that are involved in generation of the reaction force are connected to one another. The motion base as described above has a shortcoming in that a compact design configuration cannot be achieved because the motion base requires a specific member for reducing the moment or control for reducing the moment in order to reduce the moment during the turning motion of the movable base.
The present disclosure is developed in consideration of the aforementioned circumstances, and an objective of the present disclosure is to provide a motion base (i) having a compact device configuration and (ii) enabling a reduction in a moment that increases during a turning motion of a movable base.
In order to attain the aforementioned objective, a motion base according to the present disclosure includes (i) a first installation base, (ii) a first movable base on which a placement subject is to be placed, the first movable base being disposed on the first installation base, (iii) at least two first actuators each of which is extendable and contractible, (iv) first connecting portions connecting the first actuators to the first movable base, (v) second connecting portions connecting the first actuators to the first installation base, and (vi) a spherical surface body that has a spherical surface-shaped portion, is disposed on the first installation base, and supports the first movable base such that an attitude of the first movable base can be changed relative to the first installation base by sliding the spherical surface-shaped portion, wherein each of the first actuators extends and contracts between one of the first connecting portions and one of the second connecting portions and changes the attitude of the first movable base relative to the first installation base.
In this case, the first connecting portions may connect the first actuators to the first movable base such that the first actuators are able to be turned relative to the first movable base.
Also, the second connecting portions may connect the first actuators to the first installation base such that the first actuators are able to be turned relative to the first installation base.
The spherical surface body may be fixed to the first movable base with the spherical surface-shaped portion facing downward.
A two-rotational-degrees-of-freedom shake of the first movable base relative to the first installation around the roll axis and pitch axis may be achieved by extending or contracting the first actuators.
The motion base may comprise a second installation base comprising a first turntable and a second actuator to turn the first turntable, and the first installation base may be disposed on the first turntable.
A shake of the first movable base around the yaw axis may be achieved by turning the first turntable by the second actuator.
The motion base may comprise a second movable base comprising a second turntable and a third actuator to turn the second turntable, and the second movable base may be disposed on the first movable base.
A shake of the second movable base around the yaw axis may be achieved by turning the second turntable by the third actuator.
In the motion base according to the present disclosure, the spherical surface body is interposed between the first movable base and the first installation base, and the first movable base and the first installation base are connected to each other by at least two first actuators that are extendable and contractible. Most of the weight of a load received by the first movable base is supported by the first installation base through the spherical surface body.
Such a configuration of the motion base eliminates (i) the need for a member for generating a reaction force, such as an elastic member, a fastening rope or the like, and (ii) the need to dynamically control the positions of the connection of the members involved in the occurrence of the reaction force in accordance with the weight of the load, a position of the center of gravity of the load, and the like. As a result, the motion base of the present disclosure, with a compact device configuration, can reduce a moment that increases during the turning motion of the movable base.
Embodiments of the present disclosure are described below in detail with reference to the drawings. In the drawings, components that are the same or equivalent are assigned the same reference signs.
First, Embodiment 1 of the present disclosure is described. As in the appearance illustrated in
The first installation base 1a is a plate-like member installed on a floor surface or the like of a building which is not illustrated in the drawings. Although
The first movable base 2a is a plate-like member arranged above the first installation base 1a. A placement subject such as a person or a seat is loaded on the first movable base 2a (refer to
The first actuators 3a are actuators that can be extended and contracted in the longitudinal direction by driving of a control device which is not illustrated in the drawings. Actuators such as electric, hydraulic or pneumatic cylinders can be used as the first actuators 3a.
The first connecting portions 4a connect the first actuators 3a to the first movable base 2a. In the present embodiment, the first connecting portions 4a are L-shaped members. The positional relationship between the first actuators 3a and the first movable base 2a that are connected to each other by the first connecting portions 4a is unchanging.
The second connecting portions 4b connect the first actuators 3a to the first installation base 1a. Specifically, the second connecting portions 4b connect the first actuators 3a to the first installation base 1a such that the first actuators 3a can turn relative to the first installation base 1a (that is, such that the first actuators 3a have a rotational degree of freedom).
For example, regarding the second connecting portions 4b, the second connecting portions 4b can have a configuration in which ends of the first actuators 3a are formed into a spherical shape, the spherical ends are fitted to the second connecting portions 4b, and the spherical ends of the first actuators 3a slide within the corresponding second connecting portions 4b. Such a configuration enables the first actuators 3a to be turnably connected to the second connecting portions 4b. In this manner, even if the first movable base 2a turns around the roll axis and the pitch axis relative to the first installation base 1a, the first actuators 3a can be turned relative to the first installation base 1a in the second connecting portions 4b in accordance with the turn of the first movable base 2a.
As described above, the first actuators 3a extend and contract between the first connecting portions 4a and the second connecting portions 4b, thereby enabling a change in the attitude of the first movable base 2a relative to the first installation base 1a.
The spherical surface body 5 is disposed between the first installation base 1a and the first movable base 2a. More specifically, the spherical surface body 5 has a spherical surface-shaped portion 15. The spherical surface body 5 is disposed on the first installation base 1a. The spherical surface body 5 supports the first movable base 2a such that the attitude of the first movable base 2a relative to the first installation base 1a can be changed by sliding the spherical surface-shaped portion 15.
As described above, the first actuators 3a are connected to the first movable base 2a via the first connecting portions 4a and are connected to the first installation base 1a via the second connecting portions 4b. Each of the two first actuators 3a are extended or contracted, thereby enabling a change in the relative attitude of the first movable base 2a relative to the first installation base 1a.
For example, if the two first actuators 3a are extended or contracted such that an amount by which one of the two first actuators 3a is extended or contacted is different from an amount by which the other one of the two first actuators 3a is extended or contacted, the first movable base 2a can be turned around the roll axis relative to the first installation base 1a. Furthermore, if the two first actuators 3a are extended or contracted such that an amount by which one of the two first actuators 3a is extended or contacted is equal to an amount by which the other one of the two first actuators 3a is extended or contacted, the first movable base 2a can be turned around the pitch axis relative to the first installation base 1a.
Thus, a shake of the first movable base 2a relative to the first installation base 1a by two-degrees-of-freedom turns around the roll axis and pitch axis is achieved by expanding or contracting the first actuator 3a.
In the motion base 100 according to Embodiment 1, the spherical surface body 5 may be fixed to at least one of the first installation base 1a or the first movable base 2a for the purpose of stabilization.
Also, in order to facilitate a rolling motion of the spherical surface body 5 interposed between the first installation base 1a and the first movable base 2a, a wheel for receiving the spherical surface may be attached to the first installation base 1a and the first movable base 2a.
Additionally, the first installation base 1a or the first movable base 2a may be provided with a recess that comes into contact with the spherical surface body 5 and a lubricant may be applied to the surface thereof. Alternatively, the first installation base 1a or the first movable base 2a may be made of a slippery material such as Teflon (registered trademark).
In the motion base 100 illustrated in
Also, in the motion base 100 illustrated in
As illustrated in
In this case, if the spherical surface body 5 is heavy, the position of the center of gravity of the placement subject becomes low, thereby suppressing an increase in moment. Accordingly, the spherical surface body 5 is preferably heavy. Additionally, since a small-sized the spherical surface body 5 causes an increase in moment, the spherical surface body 5 is preferentially large.
In the motion bases 100 illustrated in
Also, in order to (i) connect the first connecting portions 4a to the first actuators 3a and the first movable base 2a such that the first actuators 3a can be turned relative to the first movable base 2a or (ii) connect the second connecting portions 4b to the first actuators 3a and the first installation base 1a such that the first actuators 3a can be turned relative to the first installation base 1a, a turnable element may be provided at the center of each of the first connecting portion 4a and the second connecting portion 4b. Alternatively, the turnable element may be provided on one end or both ends of each of the first connecting portion 4a and the second connecting portion 4b.
For example, when both the two first actuators 3a are extended or contracted by the same amount and in the same direction, the first movable base 2a is turned around the pitch axis as illustrated in
In this case, the contact point between the spherical surface body 5 and the first installation base 1a is shifted by a predetermined amount in accordance with a rotation angle around the pitch axis and a rotation angle around the roll axis, and the relative positional relationship between the first installation base 1a and the first movable base 2a is maintained.
In the motion base 100 according to Embodiment 1, the spherical surface body 5 is disposed between the first installation base 1a and the first movable base 2a, and at least two first actuators 3a that can extend and contract between the first installation base 1a and the first movable base 2a connect the first installation base 1a to the first movable base 2a.
Additionally, in this motion base 100, the first connecting portions 4a are connected to at least either the extendable and contractible first actuators 3a or the first installation base 1a such that the first connecting portions 4a have a rotational degree of freedom, and the second connecting portion 4b is connected to at least either the extendable and contractible first actuators 3a or the first movable base 2a such that the second connecting portions 4b have a rotational degree of freedom. Such a configuration enables an achievement of a compact and low-cost motion base without complicated control of shaking caused by the two-degrees-of-freedom turns around the roll axis and the pitch axis as loads applied to the extendable and contractible first actuators 3a are reduced.
That is, the larger the spherical surface body 5, the larger the contact area with the first installation base 1a becomes, and the first installation base 1a supports most of a load weight received by the first movable base 2a via the spherical surface body 5, even if the first movable base 2a is turned. As a result, the moment is unlikely to increase. Accordingly, the output of the first actuator 3a can be significantly reduced. Also, when the spherical surface body 5 is attached to the first movable base 2a, the heavier the spherical surface body 5, the lower the position of the center of gravity of the placement subject becomes, and thus a restoring force causing the first movable base to return to the original attitude acts on the first movable base even if the first movable base 2a is shaken, thereby making occurrence of an increase in the moment difficult, and thus the output of the first actuator 3a can be significantly reduced.
The spherical surface body 5 interposed between the first movable base 2a and the first installation base 1a does not have to be made as a solid component. The spherical surface body 5 may be made a hollow spherical component as long as the spherical surface body 5 has sufficient strength to support the weight of the first movable base 2a and the weight of the user 7 on the first movable base 2a. Also, regardless of whether the spherical surface body is a solid component or a hollow component, components that can be used as the spherical surface body 5 include, for example, a component consisting of only a rib, a component that is polygonal in shape and to which a wheel is attached, and a component that forms a spherical shape as a whole even if the shape of the component is not a perfect spherical shape.
Next, Embodiment 2 of the present disclosure is described. A motion base 101 according to Embodiment 2 differs from the motion base 100 according to Embodiment 1 in that the motion base 101 according to Embodiment 2 includes a second installation base 1b.
As illustrated in
In the motion base 101 according to the present embodiment, a servomotor is preferentially used as the second actuator 3b in order to enable the turntable to be endlessly rotatable around the yaw axis.
The first installation base 1a is placed on the turntable 8. Accordingly, a shake of the first installation base 1a around the yaw axis can be achieved by turning the turn shaft 18.
Also,
As described above, the motion base 101 according to Embodiment 2 includes the second installation base 1b that includes the turntable 8 and the second actuator 3b that can turn the turntable 8. By placing the first installation base 1a on the turntable 8, turning of the first movable base 2a around not only the roll axis and the pitch axis but also around the yaw axis can be achieved.
Also, as illustrated in
In order to show the feasibility of the present disclosure, the motion base 100 was produced experimentally, and a specific experiment was performed on the experimentally-produced motion base 100. For the experimentally-produced motion base 100, SCN6-040-150 manufactured by the Dyadic Systems Co., Ltd is used as the first actuators 3a that are extendable and contractible, and link ball screws are used as the second connecting portions 4b having a rotational degree of freedom.
The foregoing describes some example embodiments for explanatory purposes. Although the foregoing discussion has presented specific embodiments, persons skilled in the art will recognize that changes may be made in form and detail without departing from the broader spirit and scope of the invention. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense. This detailed description, therefore, is not to be taken in a limiting sense, and the scope of the invention is defined only by the included claims, along with the full range of equivalents to which such claims are entitled.
This application claims the benefit of Japanese Patent Application No. 2017-153949, filed on Aug. 9, 2017, the entire disclosure of which is incorporated by reference herein.
When a seat is provided on the first movable base, the motion bases according to the present disclosure are applicable to a driving simulator, a game or the like that enables a person to be subjected to inertial force and somatic sensation with the person sitting on the seat. Also, the motion bases according to the present disclosure can be used as a walking sensation presentation apparatus such as a slope in a state in which a person stands on the first movable base and gets on each of the motion bases. Also, the motion bases according to the present disclosure are applicable to a simulator or a game of skiing, skateboarding, and the like by providing the first movable base with a board or the like.
Number | Date | Country | Kind |
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2017-153949 | Aug 2017 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2018/029724 | 8/8/2018 | WO | 00 |