The present invention relates to a motion platform.

Motion platforms are known and used, for example, for the training of pilots but also by serious gamers to give the user of the platform a more realistic experience of operating a plane or driving a car.

A motion platform comprises a base, a platform movable with respect to the base and actuators such as hydraulic pistons for moving the moveable platform with respect to the base. This allows for various movements, such as pitch and roll, or to simulate adverse conditions such as turbulence.

Motion platforms tend to be quite expensive, and their height imposes a severe constraint on the room it is to be used. The object of the present invention is to provide a motion platform of relatively modest cost and height, the motion platform nevertheless being capable of allowing the user to experience a variety of motions including pitch and roll.

To this end, the present invention provides a motion platform comprising a mounting frame being a) supported by at least three supports and b) movable with respect to a base frame, where each support has a proximal location proximal to a first frame portion and distal end distal to said first frame portion and adjacent to a second frame portion, the first frame portions independently being part of the mounting frame or the base frame, and for a particular first frame portion the second frame portion being a portion of the other of the mounting frame and the base frame, wherein

- of the at least three supports at least said supports minus one are hingedly connected to the first frame portion at the proximal loca- tions so as to allow the distance between at least a part of the mounting frame and the base frame to be changed,

- of the at least three supports all the distal ends of said supports allow tilting movement of the respective adjacent second frame portion with respect to the distal end of the support in two directions perpendicular to each other, at least the supports hingedly connected to the first frame portion being movably connected with their distal ends to the second frame portions, wherein for each support hingedly connected to the first frame portion and movably connected to the second frame portion the second frame portion comprises a guiding so as to allow the distal end of the support to be slideably movable with respect to the second frame portion, the movable connection further allowing for a first hinging movement in a direction substan- tially parallel to the hinge movement afforded by the hinged connection of the support to the first frame portion and a second hinging movement perpendicular to the first hinging movement,

- the movable connections between the distal ends and the second frame portions and the hinged connections between the supports and the first frame portions cooperate so as to restrict movement of the mounting frame with respect to the base frame to movements that involve hinging of a support with respect to the first frame portion, and

- at least two of the supports that are hingedly connected to the first frame portions are provided with an actuator for changing the distance between at least part of the mounting frame and the base frame.

This motion platform having hinged supports to vary the distance between the mounting platform and the base platform allows for a relatively low height, because the minimum height is no longer determined by the height of the actuator. It is of modest cost yet is capable of allowing a person to experience pitch and roll very realistically. The mounting frame will be is provided with a seat for the user to sit on, or even an aircraft cockpit. Other applications in- volve, for example, providing a racecar cockpit, motorcycle seat and cockpit. For easy of description only, the mounting frame and the base frame are described as rigid units, but they could also consist of a plurality of individual smaller frame portions, that will be connected later, for example by attaching the frame portions of the mounting platform to a cockpit or to the legs of a stool or chair, thus turning the mounting platform into a rigid structure that cannot move unless the distance between at least one of the first frame portions and the second frame portions is changed. Frame portions of the base frame may be connected to the floor. This is included in the scope of the claims. In use, the actuators will be under control of a computer running motion control software, e.g. a computer running a flight simulator. The actuator is, for example, an electromotor or an hydraulic actuator. A simple embodiment of the invention is a base frame provided with a rigid upright as a first support. The mounting frame is placed on top of the upright. A person can take place on the mounting frame with his centre of gravity close to the upright. At two locations, the base frame is provided with two independently ac- tuated supports, the distal ends of which are movably connected to the mounting frame. Thus, a simple motion platform is provided capable of allowing the person to experience pitch and roll. Because the centre of gravity of the person is over the upright, that upright carries most of his weight. The two actuated supports do not have to carry much weight, with concomitant savings. The term substantially parallel means that for a support, the first hinged movement allows the slideable movement to be at an angle of less than 20° to a plane perpendicular to the axis of rotation afforded by the hinged connection of the proximal location. The angle is preferably less than 10°, more preferably less than 5°.

According to a preferred embodiment, the supports that are hingedly connected to the first frame portions are levers comprising 2 arms at an angle with each other, wherein these supports are hingedly connected to said first frame portion at the intersection of both arms, the first arm comprising said distal point and the actuator being connected to the second arm at a location away from the intersection of the two arms.

Thus a motion platform with a low lowest height can be provided. The angle of the arms is generally between 70° and 110°, and preferably between 80° and 100°, more preferably about 90°. This allows for the lowest lowest height of the motion platform. The second arms are preferably shorter than the arms with the above mentioned distal end, which also helps to reduce the lowest height of the motion platform. Preferably all the supports are hingedly connected to the first frame portions and at least 3 supports hingedly connected to the first frame portions are provided with an actuator. This allows a ^~ user to experience heave. According to a preferred embodiment, the hinging connections of the supports to the first frame portions are in a central region of the base frame, the arms having said distal ends facing outward. This provides for the maximum amount of tilt. According to a favourable embodiment, the number of supports is 3.

While more supports may be used to allow for a greater load on the mounting frame, three is an ideal number because of the simplic- ity and weight of the construction. Also, the number of actuated supports to control is limited, so the software to control the motion platform can be simpler and hence cheaper.

According to a preferred embodiment, the actuator is a fluidic muscle . The fluidic muscle allows for a compact design and relatively low cost. They also simplify the construction, as they have built-in end stops.

Preferably the fluidic muscle is connected to an air compressor. This allows for a low cost and weight, avoiding hydraulic liquids .

According to a favourable embodiment, the guidings comprise a rod and a sleeve bearing.

This allows for a smooth movement of the distal end of the sup- port with respect to the second frame.

Preferably the rod is a cylindrical rod.

This allows the translational movement and the second hinged movement to be combined in one unit, saving cost and reducing weight.

According to a very favourable embodiment, the supports that are hingedly connected to the first frame portions comprise a U profile, the rod being hingedly connected between two flanges of the U profile .

This allows for a sturdy motion platform of very low height when the mounting platform is in its lowest position (mounting frame lowered as much as possible with respect to the base frame) .

Finally, the present invention relates to a simulator comprising a motion platform according to the invention.

The simulator is advantageously a flight simulator or a simulator for a motorcycle. The present invention will now be discussed with reference to a preferred embodiment with reference to the drawing, where fig. 1 shows a motion platform according to the invention; and fig. 2 depicts a detail of the motion platform of fig. 1. Fig. 1 shows a motion platform 100 that allows a user to experience pitch, roll and heave. The motion platform 100 comprises a base frame 101 and a mounting frame 102 upon which a user can take place. To this end, the mounting frame 102 will be provided with a seat or cabin (not shown) .

The mounting frame 102 is supported by three supports 103. The supports as defined in claim 1 are generally rigid (i.e. non- telescopic) , although it is conceivable that some telescopic action could be provided. As will be clear from the following, the motion platform 100 according to the invention doesn't need this, so it is generally undesirable if the supports are telescopic (adds cost and complexity) . In the embodiment shown and according to a preferred embodiment, the supports are L-shaped and hingedly attached to a central column 104 which is part of the base frame 101. The hinges are designated 105. The L-shaped supports 103 comprise a first arm 111 and a second arm 112. For these arms, the terms proximal and distal are relative to the position of the hinge 105. The distal end of the second arm 112 is hingedly connected to a first end of a fluidic muscle 113, the second end of which is hingedly connected (via hinge 146; fig. 2) to the base frame 101. The fluidic muscle 113 is connected to an air compressor (not shown) , with valves (not shown) controlling the amount of air in the fluidic muscle 113 under control of a computer (not shown) running a flight simulator program. A high air pressure shortens the length of the fluidic muscle 113, whereas re- lease of pressure causes it to slacken. If the fluidic muscle 113 is pressurized, the distal end of the first arm 111 will rise. Suitable fluidic muscles are available from Festo, Germany.

At its underside, the mounting frame 102 is provided with a cylindrical rod 130, held by two lugs 131, one at each distal end of the first arms 111. The cylindrical rod 130 has been inserted in a sleeve bearing 132, which allows the cylindrical rod 130 to slide through the sleeve bearing 132, and also allows the sleeve bearing 132 to rotate around the cylindrical rod 130 thanks to the cylindrical nature of the rod 130. The sleeve bearing 132 is hingedly con- nected to the distal end of the first arm 111, with hinge 145 being substantially parallel to the hinge 105. For a support, deviations from parallel of the axis of rotation afforded by hinge 45 in the horizontal plane are generally undesired, although minor deviations such as those of less than 10° will not cause any significant problems. If all hinges 145 were mounted rotated over the same angle with respect to the respective hinge 105 and the sliding rods are perpendicular to the hinges 145, lowering or lifting the mounting frame 102 would cause the mounting frame 102 to perform a yaw movement, which would not be functional in improving the flight simulation experience because it would be directly correlated to the heave.

The mounting frame 102 is shown here as a triangular mounting platform. With a person looking in the direction of one of the points of the triangular mounting platform supported by a first support 103, raising the second support and lowering the third support would make the person experience roll. By lowering or raising all supports, the person would experience heave. By lowering the first support and raising the other two (or conversely) , the person would experience pitch. Rapid, relatively small pressure changes in one or more of the fluidic muscles around an average would allow a person to experience vibration.

Fig. 2 depicts a detail of the motion platform of fig. 1, similar parts having similar reference numbers. With arm 112 being shorter than arm 111, it can be seen that the motion platform allows for both a large amplitude of movement, while keeping the build height of the motion platform 100 in the collapsed state low.

Generally, for a motion platform according to the invention, the axis of rotation afforded by the hinged connection (in the above embodiment hinge 105) of the support to the first frame portion will be at an angle to the horizontal of 20° or less, preferably less than 10° and more preferably less than 5° when the base frame is placed on a horizontal floor.

It will be understood that a motion platform according to the invention can easily be enhanced with a yaw movement by providing the a rotation platform below the base frame or on top of the mounting frame .