Motion Platform

Abstract

The motion platform (2) includes a base (6) and an occupant carrier section (4). The occupant carrier section (4) is linearly movable and rotationally movable along first, second, and third orthogonal axes. The base (6) includes first, second, and third control pillars (16, 18, 20), respectively, and extends along the third axis at a predetermined height. The control pillars (16, 18, 20) are linearly movable within a plane defined by the first and second axes and are mechanically constrained to move only within that plane. The occupant carrier section (4) includes first, second, and third guide sections (28, 30, 32) pivotally connected to the first, second, and third control pillars (16, 18, 20), respectively, by respective coupling members (22, 24, 26). Each of the guide portions (28, 30, 32) is angled relative to the plane defined by the first axis and the second axis such that they are not parallel to the plane, and the guide portions (28, 30, 32) are angled relative to each other such that they are not parallel to each other.

Description

[Technical field]

[0001] The present invention relates to motion platforms, and in particular to motion platforms suitable for simulating motion where high frequency response is desired, such as, for example, automotive, motor sports and aerospace environments. [Background technology]

[0002] The motion platform can provide six degrees of freedom, allowing the occupant to be exposed to a range of motions that provide a realistic sense of being in a simulated environment. For example, the motion platform can give the occupant an accurate sense of being in a racing car, such as a Formula One car. The six degrees of freedom correspond to linear motion in surge, sway, and heave directions (i.e., along the x, y, and z axes, respectively), and rotational motion in roll, pitch, and yaw directions (i.e., about the x, y, and z axes, respectively).

[0003] The Stewart platform or hexapod platform uses a platform connected to a base unit by six telescoping struts or actuators. The device can be very large and heavy. Due to the large range of motion afforded by the struts, the device can be very tall. Typically, a large "dead space" must be provided under the platform. In this type of configuration, the struts must be relatively strong, and it is difficult to provide a high bandwidth for horizontal and vertical motion. While this type of simulator can be useful for types of aircraft that do not need to simulate high horizontal forces and accelerations, real vehicles such as racing cars can be subject to very high forces both horizontally (when braking, accelerating or cornering) and vertically (when handling ride-ups), so such simulators are generally not suitable.

[0004] One platform that is well known in the art is the "Williams" platform, as described in WO 2014 / 087172 A1. The Williams platform serves to alleviate some of the limitations of the Stewart platform, but the applicant has recognized that there is potential for further improvement.

[0005] The nature of the angled platform between the carriages of the Williams platform results in both poor authority (i.e., the ability to precisely control the motion platform) and a very low range of movement in the surge axis. It is possible to increase the angle of the "V" in the platform to increase control, but this compromises the overall surge progression. It would be desirable to have a greater range of surge motion, however, conventional configurations known in the art are themselves somewhat limited in this regard.

[0006] A limited degree of surge motion can be problematic in that it can lead to a false perception of brake fade for occupants during sustained brake cueing when travel is exhausted before cueing is terminated. Also, in conventional designs, it may be impractical to extend the range of surge motion due to the overhang hitting the floor.

[0007] Furthermore, when the platform is at either end of a surge, the center of gravity is essentially unbalanced and therefore substantially different from the default "middle" position (i.e., the position where the gas struts are adjusted to hold the majority of the static mass). This causes the gas struts, which are designed to hold the static mass of the platform in the default middle position, to be sub-optimal. This is typically very difficult to control as holding the position creates peak current demands on the motors, which can lead to system instability.

[0008] Traditional motion platforms also require a large physical footprint, especially in the sway direction (i.e. along the y-axis), which is important when considering scaling the platform where available space is limited.

[0009] Other examples in the prior art generally show multi-stage systems where one stage performs yaw, surge and sway and another stage performs heave, pitch and roll for each axis, or multiple stages are controlled for each axis. However, multi-stage systems are problematic because they negatively impact the high frequency response of the motion platform. Those skilled in the art will appreciate that the frequency response of a motion platform (i.e., its ability to perform high speed motions such as simulating the impact motions associated with hitting a road bump) is tied to the mechanical stiffness, the moving mass of the motion platform, and the actuators used to impart the motion. Typically, "stacked" layers of actuators result in very heavy systems where excess weight has a significant negative impact on the frequency response of the motion platform, especially the high frequency response. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] WO 2014 / 087172 A1 Summary of the Invention [Problem to be solved by the invention]

[0011] Applicants have recognized that there is a need for a highly capable single stage motion platform since such a platform enables heavier payloads and greater performance. [Means for solving the problem]

[0012] According to a first aspect, the present invention provides a motion platform including a base and a passenger carrier portion, the passenger carrier portion being linearly movable along first, second and third orthogonal axes and rotationally movable about the first, second and third axes, the base comprises first, second and third control pillars each extending substantially along the third axis, each of the control pillars being linearly movable within a plane defined by the first and second axes, the control pillars being mechanically constrained to move only within the plane; the occupant carrier portion comprises first, second and third guide portions, the first, second and third guide portions pivotally connected to the first, second and third control pillars, respectively, by respective coupling members; the first, second and third guide portions are angled relative to a plane defined by said first and second axes, respectively, such that said guide portions are not parallel to said plane; the first, second, and third guide portions are angled relative to one another such that no guide portion is parallel to any other guide portion; The motion platform provides a motion platform such that, in use, the first, second and third control pillars are each arranged to have a respective height along a third axis of a predetermined value.

[0013] Thus, it will be appreciated by those skilled in the art that embodiments of the present invention provide an improved motion platform with six degrees of freedom where all motion is imparted through the movement of the control pillars, which are constrained to move only in the plane of the base, e.g., in the xy plane. The relative motion of the three control pillars in the plane of the base translates to surge, sway, heave, roll, pitch and yaw motion as required. The pivotal connection between the control pillars and the inclined guides allows the motion of the control pillars in the xy plane to be translated into motion in, e.g., the z-axis. The occupant carrier is thus mechanically constrained in all six degrees of freedom by the control pillars and guides.

[0014] The control pillar based design is highly advantageous as it does not rely on push / pull rods to impart motion, therefore friction and backlash within the system is significantly reduced compared to prior art arrangements known in the art. The motion platform of the present invention can be easily integrated into motion simulators having six degrees of freedom where high movement, speed and frequency bandwidth in all axes are required.

[0015] A motion platform according to the principles of the present invention requires approximately 60% less space in the x-axis compared to conventional motion platforms. This efficient use of space is also advantageous as it allows for scaling of the motion platform. For example, compared to prior art motion platforms, the motion platform of the present invention may be substantially extended in the x-direction compared to the limitations imposed by the prior art arrangements outlined above.

[0016] It will be understood that the term "predetermined value" as used herein with respect to the respective heights of the control pillars means that the control pillars are constructed such that their respective heights are non-variable during operation, i.e., the distance between the "bottom" (the end connected to the base) and the "top" (the end pivotally attached to a suitable guide) of each control pillar is constant. A non-variable height may help to achieve greater stiffness of the system, which affects the frequency response of the motion platform, as outlined above.

[0017] The control pillars may comprise cylindrical posts in some embodiments, although other shapes are envisioned For example, the control pillars may be cubic, pyramidal, conical, or irregularly shaped in other embodiments.

[0018] The control pillars may be constructed from composite materials in some embodiments. The pillars may be constructed similarly to the "nose cones" used in Formula One cars.

[0019] In some embodiments, the respective heights of the first, second, and third control pillars are substantially the same, however, in some applications it may be desirable to provide a permanent "rake" in the motion platform, e.g., mirroring the height of a race car, and therefore in at least some embodiments, the respective heights of at least two of the first, second, and third control pillars are different.

[0020] In some embodiments, the heights of the pillars may be fixed at their respective pre-determined values ​​by making the components themselves fixed heights. That is, in some embodiments, there is no means to change the height of the control pillars. For example, the control pillars may each have a post-like structure as described above. However, in some embodiments, the height of at least one of the control pillars can be adjusted when the motion platform is not in use, and when the motion platform is in use, the height of the at least one control pillar is locked at its respective pre-determined value. For example, in some embodiments, one or more of the control pillars can include a threaded bolt member, and a portion of the coupling member is connected to the threaded bolt member. In such embodiments, the height of the control pillar can be adjusted by loosening or tightening the bolt member when the motion platform is not in operation.

[0021] As outlined above, the control pillars are arranged to move in a plane defined by the first and second axes. The base along which the control pillars move may be of any suitable shape, although in at least some examples the base is substantially planar. In one preferred set of embodiments, the plane of the base is parallel to the plane along which the first, second and third control pillars move, and is preferably coplanar with the plane along which the first, second and third control pillars move. The planar base allows for relatively simple control of the control pillars in the plane.

[0022] In one such set of embodiments, the base includes an XY table portion arranged to provide independent in-plane movement of the first, second, and third control pillars along a respective first direction and a respective second direction, the first and second directions defining a plane perpendicular to the third axis. The first and second directions are preferably orthogonal (i.e., perpendicular) to one another. The main plane of the XY table (i.e., defined by the first and second directions) is parallel to, and preferably coplanar with, the plane defined by the first and second axes. The first direction is preferably along the first axis and the second direction is preferably along the second axis, although the in-plane movement of the control pillars along the first and second directions could be angled relative to the first and second axes. Having movement of the XY table portions along the first and second axial directions makes the motion platform easier to control.

[0023] In some such embodiments, the XY table portion comprises an XY table with a first slide rail and a second slide rail that are slidably moveable relative to one another, and at least one control pillar mounted on the XY table such that sliding movement of the first slide rail moves the at least one control pillar along a first direction and sliding movement of the second slide rail moves the at least one control pillar along a second direction.

[0024] While a single XY table can provide movement for each of the control pillars, in some embodiments the XY table portion comprises a first, second and third XY table, each of said XY tables comprising a respective first and second slide rail, said slide rails being slidably movable relative to one another, and the first, second and third control pillars being mounted to the first, second and third XY tables, respectively, such that sliding movement of the first slide rail moves the corresponding control pillar along a first direction, and such that sliding movement of the second slide rail moves the corresponding control pillar along a second direction. Thus, according to such embodiments, each control pillar may be mounted on a separate XY table, with each XY table moving the control pillar in-plane.

[0025] The elements providing the in-plane motion of the control pillars may be coplanar, but in some embodiments each XY table may include a first carriage and a second carriage, said first carriage and second carriage being arranged in a stack. In general, the top carriage (i.e. the upper carriage in the stack) may be provided with an associated control pillar. It will be understood that a "stack" configuration means that the first carriage is mounted on top of the second carriage, or the second carriage is mounted on top of the first carriage. Splitting these into separate carriages and mounting them on top of separate carriages can keep the moving mass down when used with large operating envelopes. The carriages may be constructed from carbon composites to keep the mass down while retaining a relatively high stiffness, which is advantageous for the reasons discussed above. Thus, there may be a "first" carriage and a "second" carriage for each XY table.

[0026] The first carriage may comprise a control pillar, one or more bearings that move along a first direction relative to the second carriage, and a motor (e.g., a linear motor as described elsewhere herein) for driving the first carriage to move along the first direction. The bearings on the first carriage may move along bearing rails on the second carriage, the bearing rails being aligned along the first direction. The second carriage may comprise one or more bearings that move along a second direction relative to a base of the XY table, and a motor (e.g., a linear motor as described elsewhere herein) for driving the second carriage (and thus the first carriage mounted thereon) to move along the second direction. The bearings on the second carriage may move along bearing rails on the base, the bearing rails being aligned along said second direction.

[0027] Thus, in some embodiments, each XY table comprises a first carriage and a second carriage, respectively, the first carriage and the second carriage being arranged in a stack; the first carriage comprises one or more bearings for movement along a first direction relative to the respective control pillars and the second carriage, and a motor arranged to drive said first carriage along the first direction; the second carriage comprises one or more bearings for movement along the second direction relative to the base of the XY table, and a motor arranged to drive the second carriage along the second direction; the second carriage further comprises one or more bearing rails aligned along the first direction, the bearings of the first carriage engaging the one or more bearing rails of the second carriage; and The base of the XY table includes one or more bearing rails aligned along a second direction, and the bearings of the second carriage engage with the one or more bearing rails of the base.

[0028] It will of course be appreciated that the "first" and "second" carriages at the top and bottom of the stack may be reversed, so that the top carriage moves along the second direction and the bottom carriage moves along the first direction as appropriate. In such an arrangement, the second carriage may have an associated control pillar.

[0029] The XY table may provide linear motion in each of the first and second directions using, for example, one or more linear motors.

[0030] In some embodiments, the XY table may include one or more coreless linear motors. Those skilled in the art will appreciate that coreless linear motors do not include an iron core, but instead generally employ a primary component (similar to the stator of a rotary motor) constructed from multiple windings wrapped around laminated steel sheets, where these are typically embedded in an epoxy resin. Unlike iron-core motors, coreless motors avoid the presence of any attractive forces between the primary and secondary parts that may cause undesirable cogging of the motor, improving the motor's ability to move at both relatively high and low speeds with good positioning accuracy.

[0031] As outlined above, in some embodiments, motors for in-plane motion may be stacked on top of each other. One type of linear motor known in the art that can be used for both stacked carriages uses "U-channel" magnets. However, because these types of motors are heavy, it may not be desirable to stack them. In some embodiments, one or more of the XY tables use a linear shaft motor with multiple magnets arranged in a cylindrical shaft and a forcer with an electromagnetic coil that surrounds the outer periphery of the shaft along part of the shaft's length. In other words, a shaft housing a stack of "disc-shaped" magnets passes through an electromagnetic coil (i.e., the moving part) located in the forcer of the motor. Generally, the orientation of the magnets alternates between adjacent magnets such that the poles of the magnets are, for example, NS, SN, NS, etc.

[0032] As a result of such a configuration, the entire magnetic field can be used by the motor coil. In addition, these "cylinder-channel" (or "tubular") devices have significantly lower mass and also exhibit lower heat build-up when compared to U-channel devices of similar performance, which is particularly desirable. Examples of such motors are suitable for a number of applications and are commercially available, for example, from Nippon Pulse America.

[0033] In an alternative set of embodiments, the base includes a substantially circular support rail defining a plane perpendicular to the third axis, and the first, second and third control pillars are connected to a plurality of radially movable actuators, each connection between the control pillars and each radially movable actuator being provided by a respective tension member, and the radially movable actuators are arranged to move around a circumference of the circular support rail.

[0034] When simulating the movement of a car going quickly into a tight corner, a larger yaw rotation may be required to cue the sensation of turning, which is required to cue the sensation of coming out of the turn. This may be problematic with conventional motion platforms known in the art, since the motion platform is typically required to return to center (i.e., its default or null position, corresponding to zero yaw rotation) to allow for further yaw motion (e.g., for the next turn on the truck). Returning the motion platform to center may result in false sensory cues for the occupants. Traditionally, with yaw-limited platforms, the motion algorithms would have to scale the yaw cueing or apply a "washout" (continuous return to center) to the platform. This is undesirable, as the human vestibule is very sensitive to these cues.

[0035] The motion platform configuration with circular support rails according to such an embodiment advantageously provides unlimited yaw (i.e., in-plane rotation), particularly unlimited yaw about a variable center of rotation. Unlimited yaw with a variable center of rotation is highly desirable in passenger car simulators because it allows for a 1:1 ratio match of both the yaw and slip changes of a real vehicle, which is important for cueing the sensation of oversteer and understeer to the passenger's forecourt.

[0036] Thus, the circular base provided by such an embodiment does not need to be returned to center since it can make further yaw movements regardless of the angle the motion platform was previously left at.

[0037] The radially movable actuators, in at least some embodiments, can comprise respective radial linear motors each arranged to move the radially movable actuator around a substantially circular support rail.

[0038] The radially movable actuators may all move around a single track on a substantially circular support rail, although embodiments are envisioned in which the support rail includes multiple tracks and multiple radially movable actuators move around different tracks. For example, a radially movable actuator connected to one control pillar may move on a first track and an actuator connected to another control pillar may move on a second track. There may be tracks per actuator, tracks per set of actuators connected to a particular control pillar, or some combination thereof.

[0039] According to such an embodiment, the control pillar connected to the radially movable actuator can move freely in the plane (but cannot move outward as outlined above). The control pillar may, at least in some examples, be supported on the flat bed on an air bed or on low friction bearings. As used herein, the term "low friction" should be understood to mean that the frictional forces between the control pillar and the flat bed are reduced compared to when the control pillar moves across the flat bed without bearings.

[0040] In some configurations, the base comprises two radially movable actuators for each control pillar. In one such set of embodiments, the base comprises: a first control pillar connected to the first and second radially movable actuators; a second control pillar connected to third and fourth radially movable actuators; A third control pillar is arranged to be connected to the fifth and sixth radially movable actuators.

[0041] In one such set of embodiments, the base comprises: a first radially movable actuator radially adjacent to a second radially movable actuator; a third radially movable actuator radially adjacent to the fourth radially movable actuator; A fifth radially movable actuator is disposed radially adjacent to the sixth radially movable actuator.

[0042] In at least some such examples, the tension members each include a piston, and wherein each radially movable actuator includes a piston driver arranged to vary an effective length of the piston. The piston driver may extend or retract the piston to respectively lengthen or shorten the effective length of the piston. Thus, according to such embodiments, by providing two pistons per control pillar, a "scissor-like" movement of the actuators and pistons that produces in-plane movement of the control pillar can be provided.

[0043] While two radially movable actuators per control pillar are sufficient to enable in-plane movement of the control pillars as described above, in an alternative set of embodiments the base comprises three radially movable actuators per control pillar. Thus, where there are three control pillars, there may be nine radially movable actuators. Thus, in one such set of embodiments the base further comprises the first control pillar is connected to a seventh radially movable actuator; the second control pillar is connected to an eighth radially movable actuator; The third control pillar is arranged to be connected to a ninth radially movable actuator.

[0044] Providing at least three radially movable actuators per control pillar allows the use of cables as tension members, and thus in at least some such embodiments the tension members each comprise a cable and each radially movable actuator comprises a cable motor arranged to vary the effective length of the cable, the cable motor being able to "wind up" the cable, thereby shortening its effective length, and / or winding or unwinding the cable.

[0045] In one potentially overlapping set of embodiments, the base comprises: a seventh radially movable actuator radially adjacent to the third and sixth radially movable actuators; an eighth radially movable actuator radially adjacent to the second and fifth radially movable actuators; A ninth radially movable actuator is disposed radially adjacent to the first and fourth radially movable actuators.

[0046] In at least some such embodiments, the angle between each of the radially movable actuators connected to each control pillar is substantially equal to 120 degrees. Thus, according to such embodiments, each of the first, second, and seventh radially movable actuators, each of the third, fourth, and eighth radially movable actuators, and each of the fifth, sixth, and ninth radially movable actuators are spaced apart by an angle of about 120 degrees such that the actuators within each group are equally spaced apart. However, it will be appreciated that these angles may be adjusted as desired, for example, to prevent the tension members from interfering with other control pillars.

[0047] Regardless of the type of base used, the physical layout of the control pillars and guides may be varied according to design requirements. However, in some embodiments, the guides are The first guide portion is located at a front center portion of the passenger carrier portion, The second guide portion is located on the rear left side of the passenger carrier portion, The third guide portion is positioned to be located at the rear right side of the passenger carrier portion. In other words, in such an embodiment, the motion platform may be mounted such that one control pillar is connected to the front of the passenger carrier (i.e., under the "nose" of the passenger carrier) and the other two control pillars are connected to the rear of the passenger carrier (i.e., under the "tail" of the passenger carrier, one per side). It will be understood that other layouts are envisioned, for example with two control pillars at the front and one control pillar at the rear.

[0048] In a configuration with a "first" guide section forward and a "second" and a "third" guide section at the rear, the first guide section can be moved closer to or farther from the second and third guide sections depending on the requirements of the application. By moving the front (i.e., first) guide section further away from the rear (i.e., second and third) guide sections, the amount of pitch is reduced but the center of gravity is lowered, which may be preferable for certain simulation applications, such as for motorsports. Having the front guide section further forward can also increase the space available for mounting the car's console and seats. Moving the front guide section further forward can also increase the yaw envelope around the passenger's forecourt, for example to about 60 degrees.

[0049] Although the motion platform of the present invention requires the presence of three control pillars, in some embodiments the base may comprise one or more further control pillars each extending substantially along a third axis, each of the further control pillars being linearly movable in a plane defined by the first and second axes, the further control pillars being mechanically constrained so that they only move in said plane. For example, a fourth control pillar may be provided such that the passenger carrier part is attached to the base at four points. In such an embodiment, the control pillars may be located at different corners of the passenger carrier part, for example, front-left, front-right, rear-left, and rear-right, respectively, or may be located at the extremes along the surge and sway directions such that the control pillars are located at the front, rear, center-left, and center-right. Providing further control pillars may result in an over-constrained system and may be particularly advantageous when the base must support a relatively high mass.

[0050] In some embodiments, the guide portions each include a guide rail that defines a track along which movement of the respective linkage member is constrained.

[0051] While the guide sections can be entirely rigid structures (e.g., the guide rails outlined above along which the coupling members slide), in some embodiments, one or more of the guide sections include a resilient member. The resilient member can comprise, for example, a spring, such as a mechanical spring. However, in at least some examples, the resilient member comprises a gas strut. In a preferred set of embodiments, all of the guide sections include a respective gas strut.

[0052] Those skilled in the art will appreciate that gas struts use compressed gas contained in a sealed cylinder enclosed by a sliding rod to pneumatically store potential energy to resist any external force applied in the direction of the rod. In some such embodiments, the gas strut comprises a rod end and a cylinder end, and a coupling member connects the control pillar to the rod end of each gas strut. The gas strut (or equivalently, a different type of elastic member, if appropriate) dampens movement of the platform and assists the motion platform in supporting the mass of the occupant carrier section when it moves away from the central position.

[0053] The first, second, and third guide sections are each angled relative to the plane defined by the first and second axes so that when viewed in side view, the guide sections will be understood to be "angled," i.e., angled upwards / downwards. The actual angles may be varied according to design parameters, for example, to provide more or less control in heave, pitch, or roll.

[0054] However, in some embodiments, the angle between the at least one guide portion and the plane defined by the first and second axes is between 10 degrees and 70 degrees, preferably between 20 degrees and 60 degrees, and more preferably between 25 degrees and 55 degrees. In one set of embodiments, the angle between the at least one guide portion and the plane defined by the first and second axes is about 26.5 degrees. A 26.5 degree angle between the guide portion and the plane of the first and second axes may provide a 2:1 ratio for the actuators. In a potentially overlapping set of embodiments, the angle between the at least one guide portion and the plane defined by the first and second axes is about 45 degrees. The 45 degree angle is advantageous because it reduces the in-plane force required from each actuator to lift the occupant carrier portion (i.e., out-of-plane). In at least some embodiments, the angle between the first guide portion and the plane defined by the first and second axes is approximately 26.5 degrees, and the angle between each of the second and third guide portions and the plane defined by the first and second axes is approximately 45 degrees.

[0055] Of course, the first, second, and third guide sections are angled relative to one another such that each guide section is not parallel to the others, so that in plan view the guide sections are "angled," i.e., convergent / divergent from one another. As noted above, the actual angles may vary according to design parameters.

[0056] However, in some embodiments, the angle between the first, second, and third guide portions is between 70 degrees and 150 degrees, preferably between 80 degrees and 140 degrees, and more preferably between 90 degrees and 135 degrees. In one set of embodiments, the angle between the first guide portion and each of the second and third guide portions is about 135 degrees. In a potentially overlapping set of embodiments, the angle between the second guide portion and the third guide portion is about 90 degrees.

[0057] In some embodiments, the angle between the second and third guide sections is approximately 100 degrees. As compared to a 90 degree angle, an arrangement with a 100 degree angle between these two guide sections may exhibit increased stiffness in the surge axis. This increased angle may increase the size of the platform, which may be beneficial for fitting to a particular chassis or seat.

[0058] Those skilled in the art will appreciate that there are numerous pivot connection types known in the art that can be used to provide a pivot connection between the control pillar and the guide portion. However, in some embodiments, one or more of the coupling members includes a spherical ball joint. In other embodiments, one or more of the coupling members includes a gimbal or universal connector.

[0059] In a particular set of embodiments in which one of the coupling members comprises a gimbal, the gimbal may preferably be constructed from high tensile steel. The gimbal may be disposed at approximately 90 degrees to the respective guide portion in some embodiments. In other words, the gimbal is substantially perpendicular to the guide portion, e.g., perpendicular to the gas strut. Having the gimbal at this angle may advantageously increase stiffness and help ensure that gimbal lock is not reached in pitch and / or roll conditions.

[0060] The passenger carrier section may include a seat, a steering column, and pedals. Of course, in practice there may be more or fewer components, and the layout of the passenger carrier section may vary depending on the application (e.g., when used as a flight simulator instead of a car simulator).

[0061] The components within the passenger carrier section may be mounted within a frame. For example, the passenger carrier section may have a tubular frame construction. However, in some embodiments, the passenger carrier section has a monocoque construction. A monocoque construction may advantageously provide a rigid yet lightweight structure. If desired, construction techniques similar to those used in the construction of the "Formular One" chassis may be used. The monocoque structure may include composite materials.

[0062] As mentioned above, movement of the passenger carrier section can be accomplished by use of an XY table or an "unlimited yaw" circular support ring. However, both of these may also be combined such that the XY table is mounted on an "unlimited yaw" ring. Thus, in some embodiments, the base is a primary stage comprising an XY table portion configured to provide independent in-plane movement of the first, second, and third control pillars along respective first directions and respective second directions, the first and second directions defining a plane perpendicular to the third axis; a secondary stage including a substantially circular support rail and defining a plane perpendicular to the third axis; the XY table portion is attached to the support rail via a radially movable bearing member configured to move around a circumference of the circular support rail; The secondary stage includes a radial motor disposed to drive rotational movement of the primary stage relative to the secondary stage.

[0063] Such an arrangement may therefore provide the benefits of both the XY table and unlimited yaw. Specifically, the XY table provides a "primary stage" used for cueing motion in surge, sway and heave directions (i.e. along the x, y and z axes, respectively), and rotational motion in roll, pitch and yaw directions (i.e. along the x, y and z axes, respectively). The unlimited yaw (i.e. the circular support rail and radially movable bearing members) provides a "secondary stage" that overcomes any potential issues with the motion platform "running out" of yaw on the primary stage. While including both may increase the overall size and mass of the motion platform, increasing the yaw available on the primary (XY table) stage is also highly advantageous for cueing 1:1 yaw at fast accelerations. Having a primary stage with such a high rate of yaw available with low yaw inertia means that rapid accelerations can be replicated on the motion platform.

[0064] The yaw table complements the primary stage to ensure that yaw travel remains highly dynamic and unlimited. As long as the yaw table can accelerate to maximum speed in the time it takes the primary stage to reach its rotation limit, there should be no degradation in performance when these stages are stacked.

[0065] As outlined above, the primary (i.e. XY table) stage can rotate around the circumference of a circular support rail on bearing members. These bearing members (or "bearing blocks") may be directly connected to the XY table portion, but in some embodiments the motion platform further comprises a bed positioned between the bearing members and the XY table portion, such that the XY table portion is mounted on or includes the bed, such that the bed is mounted on the bearing members. Alternatively, the bed may form an integral part of the XY table portion.

[0066] In some embodiments, the secondary stage may comprise a plurality of concentric substantially circular support rails, each of which is coplanar and defines a respective plane perpendicular to the third axis. Where the XY table is provided with radially movable bearing members (i.e., bearing blocks) that move around the circumference of the circular support rails as described above, these may move around one of the concentric circular support rails while the others simply provide support, but in some examples the radially movable bearing members may move around one or more of the concentric circular support rails, potentially all of the concentric circular support rails. In one particular set of embodiments, the yaw table may comprise three concentric support rails. However, configurations having a different number of rails may suit particular applications as appropriate.

[0067] Typically, the radial motor will be positioned such that its forcer (i.e., the moving part) is connected to the XY table, or to the intermediate bed in embodiments where an intermediate bed is provided. The fixed magnets of the radial motor will typically be fixed relative to the yaw table, for example they may be fixed to the base of the yaw table. There are many radial motors known in the art, but in some examples the radial motor may comprise a radial linear motor.

[0068] It will be appreciated that any of the features discussed above in relation to the XY table and circular support rail configuration also apply, alone and where appropriate, to a set of embodiments in which these two configurations are used in combination. [Brief description of the drawings]

[0069] Specific embodiments of the present invention will now be described with reference to the accompanying drawings. [Figure 1] FIG. 1 is an isometric view of a motion platform in accordance with one embodiment of the present invention. [Diagram 2]FIG. 2 is an isometric view of the passenger carrier portion of the motion platform of FIG. [Diagram 3] FIG. 3 is a schematic plan view showing the center position of the motion platform of FIG. [Figure 4a] ~ [Figure 4f] 4a-4f are schematic plan views illustrating the six degrees of freedom provided by the motion platform of FIG. [Diagram 5] FIG. 5 is an isometric view of a guide employing gas struts in accordance with an embodiment of the present invention. [Figure 6] FIG. 6 is a plan view of the XY table base of a motion platform in accordance with an embodiment of the present invention. [Figure 7] FIG. 7 is an isometric view of a cross section of the base of the XY table of FIG. [Figure 8] FIG. 8 is an isometric view of the XY table base of FIG. [Figure 9] FIG. 9 is a top view of a motion platform on an infinite yaw base in accordance with an embodiment of the present invention. [Figure 10] FIG. 10 is an isometric view of the unlimited yaw base of FIG. [Figure 11] FIG. 11 is an isometric view of a motion platform on a further infinite yaw base in accordance with one embodiment of the present invention. [Figure 12] FIG. 12 is an isometric view of the unlimited yaw base of FIG. [Figure 13] FIG. 13 is an isometric view of a motion platform in accordance with a further embodiment of the present invention. [Figure 14] FIG. 14 is a top view of the motion platform of FIG. [Figure 15] FIG. 15 is a further isometric view of the motion platform of FIG. 13 showing the integral chassis. [Figure 16] FIG. 16 is an isometric view of a guide portion employing a gimbal. [Figure 17] FIG. 17 is an isometric view of the stacked XY table bases. [Figure 18] FIG. 18 is an isometric view of a motion platform with a yaw table stage in accordance with one embodiment of the present invention. [Figure 19A] ~ [Figure 19B] 19A and 19B are further isometric views of the motion platform of FIG. [Figure 20] 20 is a plan view of a yaw table used in the motion platform of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0070] Figure 1 is an isometric view of a motion platform 2 according to one embodiment of the present invention. The motion platform 2 comprises a passenger carrier portion 4 and a base 6. In the example shown in Figure 1, the base 6 includes an XY table, although a circular "unlimited yaw" base could be used instead, as outlined below with reference to Figures 9 and 10.

[0071] The six degrees of freedom of the motion platform 2 correspond to linear motion in surge, sway, and heave directions (i.e., along the x, y, and z axes, respectively), and rotational motion in roll, pitch, and yaw directions (i.e., about the x, y, and z axes, respectively).

[0072] The passenger carrier section 4 comprises a seat 8, a steering column 10, and pedals 12 mounted within a frame 14. Of course, in practice there may be more or fewer components, and the layout of the passenger carrier section 4 may vary depending on the application (e.g., when used as a flight simulator instead of a car simulator). The passenger carrier section 4 of the motion platform 2 can be seen in more detail in FIG. 2, which provides an isometric view of the passenger carrier section 4.

[0073] The base 6 comprises three control pillars 16, 18, 20, two of which - the front control pillar 16 and the rear left control pillar 18 - are shown in Figure 1, whilst the rear right control pillar 20 is hidden from view by the passenger carrier part 4. The layout of all three control pillars 16, 18, 20 can be readily seen from Figures 3, 4a-f and 8.

[0074] In this example, each control pillar 16, 18, 20 is constructed as a cylindrical "post". Importantly, each pillar 16, 18, 20 is of a fixed height such that the distance from the top to the bottom of the pillar 16, 18, 20 (i.e., in the z-direction) cannot vary. At the top of each control pillar 16, 18, 20 is provided a spherical ball joint 22, 24, 26.

[0075] In this particular example, the spherical ball joints 22, 24, 26 are connected to respective threaded bolts 23, 25, 27 (i.e., threaded members) that can be loosened or tightened to change the predetermined height of the corresponding control pillars 16, 18, 20. Since the height of each of the control pillars 16, 18, 20 remains constant while the motion platform 2 is in use, any adjustments in the predetermined height of the control pillars 16, 18, 20 are performed while the motion platform 2 is not actuated.

[0076] The passenger carrier section 4 comprises three guide rails 28, 30, 32, two of which - the front rail 28 and the rear left rail 30 - are shown in Figures 1 and 2, while the rear right guide rail 32 is hidden from view by the remainder of the passenger carrier section 4. The layout of all three guide rails 28, 30, 32 can be readily seen from Figure 6.

[0077] The angle θ between the front guide rail 28 and the xy plane defined by the x and y axes is approximately 26.5 degrees. The angle φ between the rear guide rails 30, 32 and the xy plane is approximately 45 degrees. The 45 degree angle φ is advantageous because it reduces the in-plane force required from each actuator to lift the passenger carrier section 4, i.e., out-of-plane heave motion in the z-axis direction.

[0078] As can be more easily seen with reference to the plan view of the motion platform 2 shown in Figure 6, the guide rails 28, 30, 32 are also angled relative to one another. The angle α between the front guide rail 28 and each rear guide rail 30, 32 is approximately 135 degrees, while the angle β between the rear guide rails 30, 32 is approximately 90 degrees.

[0079] As a non-limiting example, by angling the rear rails (in plan view) 90 degrees to each other so that the angle is 45 degrees to both the x and y axes when the platform is in the center (i.e. null) position, the force required to move the rear left or right corners is shared equally by the x and y actuators. However, when in the center position, the guides are parallel to the y axis, which means that lifting the front of the passenger carrier section up or down may require the y actuators to provide all of the force required. By design, this is not generally an issue when the center of gravity is on the rear pillar, since the force required to lift the front is significantly less than the rear. As a result, the actuators in the x axis do not need to provide any force to move the front of the passenger carrier up or down, which means that there is a maximum force available for yaw movement. This can be highly desirable in some applications.

[0080] The spherical ball joints 22, 24, 26 provided at the top of each control pillar 16, 18, 20 are pivotally attached to guide rails 28, 30, 32. Specifically, the ball joint 22 at the top of the front control pillar 16 is connected to the front guide rail 28, the ball joint 24 at the top of the rear left control pillar 18 is connected to the rear left guide rail 30; and the ball joint 26 at the top of the rear right control pillar 20 is connected to the rear right guide rail 32. These spherical ball joints 22, 24, 26 are therefore coupling members that can slide along the respective guide rails 28, 30, 32 and tilt the occupant carrier section 4.

[0081] Since the control pillars 16, 18, 20 are each fixed height, the occupant carrier section 4 cannot move in any axis without moving the control pillars 16, 18, 20, which are mechanically constrained by them. The motion platform 2 could also use a circular "unlimited yaw" platform as described with reference to Figures 11 and 12 below (or another suitable arrangement), but in any such arrangement, the underlying design principle is that motion of the control pillars 16, 18, 20 in the x and y directions (i.e. in the xy plane) can be converted to out-of-plane motion in the z direction by positioning the control pillars 16, 18, 20 at known positions to force the control pillars 16, 18, 20 to move to a desired attitude. Such motion is outlined in further detail with reference to Figures 3 and 4a-f.

[0082] Figure 3 is a schematic plan view showing the center position of the motion platform 2 of Figure 1. The control pillars 16, 18, 20 can each move independently in the x and y directions, i.e., in the xy plane. For ease of understanding, the schematics of Figures 3 and 4a-f simplify the configuration of the motion platform 2 for illustrative purposes only.

[0083] In this center or "null" position, the motion platform 6 is not subject to any surge, sway, heave, roll, pitch or yaw motions, i.e., it is the "default" position of the motion platform 2.

[0084] 4a-f are schematic plan views showing the six degrees of freedom provided by the motion platform 2 of FIG. 1. Specifically, these schematics illustrate the movements of the control pillars 16, 18, 20 executed to achieve surge, sway, heave, pitch, roll, and yaw movements. Of course, it will be understood that the particular set of movements shown is a limited set shown for illustrative purposes to depict the respective positions of the control pillars 16, 18, 20 for a maximum of each movement in one direction. In practice, the control pillars 16, 18, 20 for moving the passenger carrier section 4 will shift between these positions as appropriate for the desired cueing.

[0085] Figure 4a shows the positions of the control pillars 16, 18, 20 that achieve maximum positive surge motion, i.e., surge motion in the x-axis. To achieve this, all three control pillars 16, 18, 20 are moved in the positive x-axis direction, while the y-axis positions of the control pillars 16, 18, 20 are not altered. Moving all three control pillars 16, 18, 20 in the negative x-axis direction would instead result in negative surge motion.

[0086] Figure 4b shows the positions of the control pillars 16, 18, 20 that achieve maximum positive sway motion, i.e., movement in the y-axis. To achieve this, all three control pillars 16, 18, 20 are moved in the positive y-axis direction, while the x-axis positions of the control pillars 16, 18, 20 are not altered. Moving all three control pillars 16, 18, 20 in the negative y-axis direction would instead result in negative surge motion.

[0087] 4c shows the position of the control pillars 16, 18, 20 that achieves maximum positive heave motion, i.e., movement in the z-axis. To achieve this, all three control pillars 16, 18, 20 are moved towards the centre of the base 4 by moving them in the x and y-axis directions accordingly. In this example, the guide rails 28, 30, 32 are all angled "upwards" such that moving the three control pillars 16, 18, 20 towards the centre means that the mass of the occupant carrier section 4 is pushed upwards (i.e. as the pivot connections of the control pillars 16, 18, 20 shift in the z-axis direction towards the lowest point of the guide rails).

[0088] Moving all three control pillars 16, 18, 20 away from the center of the base 4 will result in a negative heave motion, ie in the opposite direction in the z-axis.

[0089] If the guide rails 28, 30, 32 were all angled "downward," moving the control pillars 16, 18, 20 in this manner would instead result in a negative heave motion. The angling of the guide rails 28, 30, 32 may instead be "misaligned," such that some of the guide rails 28, 30, 32 are angled upward and some are angled downward, causing the control pillars 16, 18, 20 to move inward or outward.

[0090] Figure 4d shows the position of the control pillars 16, 18, 20 that achieves maximum positive pitch motion, i.e., movement about the y-axis. To achieve this, the front control pillar 16 moves toward the center of the base 6 while the rear control pillars 18, 20 move away from the center of the base 6. Because of the angling of the guide rails 28, 30, 32, this causes the passenger carrier section 4 to rotate about the y-axis such that the "nose" of the passenger carrier section 4 is tilted upwards.

[0091] Moving the front control pillar 16 away from the center of the base 6 while moving the rear control pillars 18, 20 toward the center of the base 6 will result in a negative pitch motion instead.

[0092] FIG. 4e shows the position of the control pillars 16, 18, 20 that achieves maximum positive roll motion, i.e., roll motion about the x-axis. To achieve this, the front control pillar 16 is left in a null position while the rear left control pillar 18 moves away from the center of the base 6 and the rear right control pillar 20 moves toward the center of the base 6. This causes the passenger carrier section 4 to rotate about the x-axis such that the passenger carrier section 4 "banks" to one side. If the movement of the rear control pillars 18, 20 were reversed (i.e., the rear left control pillar 18 moves toward the center and the rear right control pillar 20 moves away from the center), the passenger carrier section 4 would rotate in the other direction about the x-axis such that the passenger carrier section 4 banks to the opposite side.

[0093] Figure 4f shows the position of the control pillars 16, 18, 20 that achieves the maximum positive yaw movement, i.e. about the z-axis. To achieve this, all three control pillars 16, 18, 20 are moved clockwise towards the position of the next control pillar 16, 18, 20. This causes the occupant carrier part 4 to rotate about the z-axis such that the occupant carrier part 4 "pivots" in place. Moving the three control pillars 16, 18, 20 counterclockwise would, of course, instead result in a negative yaw movement, i.e. a movement about the z-axis in the opposite direction.

[0094] Figure 5 is an isometric view of a guide employing gas struts according to one embodiment of the present invention. As can be seen from Figure 5, the above-mentioned guide rails 28, 30, 32 may be provided with a gas strut (i.e., gas spring) 34. The gas strut 34 is composed of a cylinder end 36 and a rod end 38, where the cylinder end 36 is filled with a gas medium enclosed by the rod end 38. As the gas medium is gradually compressed, the rod end 38 moves into the cylinder end 36.

[0095] The spherical ball joints 22, 24, 26 at the top of the appropriate control pillars 16, 18, 20 may be connected to one end, such as a rod end 38, of a gas strut 34. The gas strut 34 provides damping and helps to support the mass of the occupant carrier section 4. However, the use of gas struts is not required and the spherical ball joints 22, 24, 26 may instead be connected to slide along guide rails 28, 30, 32.

[0096] Figure 6 is a plan view of a motion platform on an XY table base 6 according to one embodiment of the present invention. The XY table base 6 is seen more closely in Figure 7, which is an isometric view of a cross section of the XY table base of Figure 6, specifically one of the three XY tables 7a-7c. Figure 8 provides an isometric view of the entire XY table base 6 of Figure 6.

[0097] The XY table base 6 consists of three XY tables 7a-c, one for each control pillar 16,18,20.

[0098] Each of the XY tables 7a-7c includes first and second slide rails 38a-38c, 40a-40c that are slidably movable relative to one another, i.e., they are slidable adjacent to one another under the control of, for example, linear motors. There are numerous XY table arrangements known in the art, however, in this example, the XY table base 6 uses six ball screw actuators, i.e., two per XY table 7a-c.

[0099] Each slide rail 38a-38c, 40a-40c provides movement along one of two orthogonal directions, either the x-axis direction or the y-axis direction (with one slide rail 38a-38c, 40a-40c per direction). In this example, the first slide rail 38a-38c provides movement along the x-axis direction and the second slide rail 40a-c provides movement along the y-axis direction. Thus, the sliding movement of the first slide rail 38a-38c moves the corresponding control pillar 16, 18, 20 along the x-axis (i.e. surge) direction and the second slide rail 40a-40c moves the corresponding control pillar 16, 18, 20 along the y-axis (i.e. sway) direction. Thus, each XY table 7a-c moves the control pillar 16, 18, 20 in the xy plane.

[0100] Figure 9 is a plan view of a motion platform 102 on an infinite yaw base 106 in accordance with one embodiment of the present invention. Figure 10 is an isometric view of the motion platform 102 of Figure 9. The motion platform 102 comprises a passenger carrier portion 104 and a base 106, which comprises at least three guide rails (not shown in Figures 9 and 10) angled relative to the xy plane and relative to each other, as previously described with respect to the motion platform 2 of Figure 1.

[0101] The base 106 comprises first, second and third control pillars 110, 112, 114 connected to a plurality of radially movable actuators 116a-f. The connection between the control pillars 110, 112, 114 and the angled guide rails on the occupant carrier section 104 is provided by a pivot connection as described above. The control pillars 110, 112, 114 of the base 106 shown in Figures 9 and 10 are conical rather than cylindrical, but still have a fixed height. Of course, these control pillars 110, 112, 114 may instead be cylindrical (and similarly, the control pillars 16, 18, 20 described above may be conical; any of the control pillars 16, 18, 20, 110, 112, 114 described herein may take any suitable shape).

[0102] Each control pillar 110, 112, 114 is connected to two actuators 116a-f, such that the first (i.e., front) control pillar 110 is connected to a first 116a and a second 116b radially movable actuator. The second (i.e., rear-left) control pillar 112 is connected to a third 116c and a fourth 116d radially movable actuator, and the third (i.e., rear-right) control pillar 114 is connected to a fifth 116e and a sixth 116f radially movable actuator.

[0103] Each connection between the control pillars 110, 112, 114 and a respective radially movable actuator 116a-f is provided by a respective piston 118a-f (i.e., a tension member). The radially movable actuators 116a-f are arranged to move around the circumference of a circular support rail 108 which provides a track for the movement of the actuators 116a-f.

[0104] The radially movable actuators 116a-f each include a piston driver 120a-f arranged to vary the effective length of the corresponding piston 118a-f. The piston drivers 120a-f can extend or retract the pistons 118a-f to lengthen or shorten the pistons 118a-f. The actuators 116a-f also each include a respective radial linear motor 122a-f that provides movement of the radially movable actuators 116a-f about the circular support rail 108, such that the motion of the control pillars 110, 112, 114 is mechanically constrained to in-plane movement only (i.e., in the xy plane).

[0105] The configuration of the motion platform 102 with the circular support rails 108 advantageously provides unlimited yaw (i.e., in-plane rotation in the xy plane), where the center of rotation may vary as desired. Such variably infinite yaw is possible, which is highly desirable, because the vehicle simulator can match the yaw and slip variations of a real car in a 1:1 ratio that is important for cuing the sensation of oversteer or understeer in the occupant's forecourt.

[0106] By moving the radially movable actuators 116a-f around the circumference of the circular support rail 108 and lengthening and shortening the pistons 118a-f appropriately, the motion platform 102 provides surge, sway, pitch, roll and yaw movements by moving the control pillars 110, 112, 114 only in the xy plane using the "scissors" movement of the actuators 116a-f. The configuration of the control pillars 110, 112, 114 that provide each of these motions is substantially the same as that described in Figures 4a-f (assuming that the guide rails of the occupant carrier section 104 in the motion platform 102 match those of the occupant carrier section 4 in the motion platform 2 of Figure 1), except that there is no longer a "center" position for the in-plane (i.e., in the xy plane) rotation of the occupant carrier section 104.

[0107] Figure 11 is a plan view of a motion platform 202 on an infinite yaw base 206 in accordance with a further embodiment of the present invention. Figure 12 is an isometric view of the motion platform 202 of Figure 11. The motion platform 202 comprises a passenger carrier portion 204 and a base 206, which is provided with at least three guide rails (not shown in Figures 11 and 12) angled with respect to the xy plane and with respect to each other, as previously described with respect to the motion platform 2 of Figure 1.

[0108] 11, a base 206 includes a substantially circular support rail 208. The circular support rail 208 provides a track along which a number of radially movable actuators can move in the xy plane, i.e., the plane of the support rail 208 is perpendicular to the z-axis.

[0109] The base 206 comprises first, second and third control pillars 210, 212, 214 connected to a plurality of radially movable actuators 216a-216i. The connection between the control pillars 210, 212, 214 and the angled guide rails on the occupant carrier section 204 is provided by a pivot connection as described above. The control pillars 210, 212, 214 of the base 206 shown in Figures 11 and 12 are conical rather than cylindrical, but still have a fixed height. Of course, these control pillars 210, 212, 214 may instead be cylindrical (and as outlined above, the control pillars 210, 212, 214 described may take any suitable shape).

[0110] Each control pillar 210, 212, 214 is connected to three actuators 216a-216i, such that the first (i.e., front) control pillar 210 is connected to a first radially movable actuator 216a, a second radially movable actuator 216b, and a seventh radially movable actuator 216g. The second (i.e., rear-left) control pillar 212 is connected to a third radially movable actuator 216c, a fourth radially movable actuator 216f, and an eighth radially movable actuator 216h. The third (i.e., rear-right) control pillar 214 is connected to a fifth radially movable actuator 216e, a sixth radially movable actuator 216f, and a ninth radially movable actuator 216i.

[0111] Each connection between the control pillars 210, 212, 214 and each radially movable actuator 216a-216i is provided by a respective cable 218a-218i (i.e., a tension member). The radially movable actuators 216a-216i are arranged to move around the circumference of a circular support rail 208 which provides a track for the movement of the actuators 216a-216i.

[0112] Each of the radially movable actuators 216a-i includes a cable motor 120a-i arranged to vary the effective length of the corresponding cable 218a-i. The cable motors 120a-i can "wind up" the cables 218a-i to shorten the effective length, and / or can unwind or unwind the cables 218a-i. Additionally, each of the actuators 216a-i includes a respective radial linear motor 122a-i that provides movement of the radially movable actuators 216a-i about the circular support rail 208, such that the motion of the control pillars 210, 212, 214 is mechanically constrained to in-plane movement only (i.e., in the xy plane).

[0113] The configuration of the motion platform 202 with the circular support rails 208 advantageously provides unlimited yaw (i.e., in-plane rotation in the xy plane), where the center of rotation may vary as desired. Such variably infinite yaw is possible, which is highly desirable, because the vehicle simulator can match the yaw and slip variations of a real car in a 1:1 ratio that is important for cuing the sensation of oversteer or understeer in the occupant's forecourt.

[0114] By moving the radially movable actuators 216a-216i around the circumference of the circular support rail 208 and lengthening and shortening the cables 218a-218i appropriately, the motion platform 202 provides surge, sway, heave, pitch, roll and yaw motions by moving the control pillars 210, 212, 214 only in the xy plane. The configuration of the control pillars 210, 212, 214 that provide each of these motions is substantially the same as that described in Figures 4a-f (assuming that the guide rails of the passenger carrier section 204 in the motion platform 202 match those of the passenger carrier section 4 in the motion platform 2 of Figure 1), however, there is no longer a "center" position for in-plane (i.e., in the xy plane) rotation of the passenger carrier section 204.

[0115] Figure 13 is an isometric view of a motion platform 302 in accordance with a further embodiment of the present invention. Further views of the motion platform 302 can be seen in Figures 14 and 15. In particular, Figure 14 is a top view of the motion platform 302, and Figure 15 provides a further isometric view of the motion platform 302 showing the integrated chassis used in the passenger carrier portion 304 (which is now simplified in Figures 13 and 14 for ease of illustration).

[0116] In this embodiment, the passenger carrier portion 304 is attached to three XY tables 306a-303c via respective pillars 316, 318, 320. However, in this embodiment, the pillars 316, 318, 320 are pyramidal shaped structures.

[0117] Each of the pillars 316, 318, 320 is connected to a respective guide section 328, 330, 332 on the underside of the passenger carrier section 304 via a gimbal 334, as can be seen more clearly in the close-up view of Figure 16. The gimbal 334 is connected to a pair of bearing rails 336 on the guide sections 328, 330, 332 via bearings 338 disposed on the gimbal 334. These allow the gimbal 334 to slide along the bearing rails 336.

[0118] A further difference from the previously described embodiment is that in the motion platform 302 of Fig. 13, the XY tables 306a-303c are each constructed from stacked carriages, where the carriages 308a-308c for movement in the y direction are located at the bottom and the carriages 310a-310c for movement in the x direction are mounted on top of the y carriages 308a-308c. The carriages 308a-308c, 310a-c are constructed from composite material. Of course, other configurations with the x carriages at the bottom and the y carriages at the top could be used instead.

[0119] FIG. 17 provides an enlarged view of a portion of the XY table, where a closer view of the structure of the x-carriages 310a-310c and y-carriages 308a-308c can be seen.

[0120] Each of the y-carriages 308a-308c includes a respective linear motor 312. These "U-channel" linear motors 312 of the y-carriages 308a-308c run along respective magnet tracks 313. Each of the y-carriages 308a-308c has a number of bearings 350 on its underside that allow the y-carriages 308a-308c to slide along bearing rails 352 on the base 315 below the respective y-carriages 308a-308c.

[0121] The x-carriages 310a-c include respective pillars 316, 318, 320. When the x-carriages 310a-310c are mounted on top of corresponding y-carriages 308a-308c, movement of any given y-carriage 308a-308c along the y-axis also causes the respective x-carriage 310a-310c, and therefore its control pillars 316, 318, 320, to move along the y-axis.

[0122] The x-carriages 310a-c also include a number of bearings 344 that slide along bearing rails 346 on the y-carriages 308a-c below them. This allows the x-carriages 310a-c - and thus the pillars 316, 318, 320 - to move along the x-axis on top of the corresponding y-carriages 308a-308c. The x-carriages 310a-c also include respective linear motors 314 that provide this motion along the x-axis.

[0123] The particular construction of the linear motors 314 used in the x-carriages 310a-c is discussed in detail below, although it will be understood that similar principles of operation apply with respect to the U-channel linear motors of the y-carriages 308a-c.

[0124] Each of the linear motors 314 in the x-carriages 310a-310c utilizes a cylindrically stacked disk-shaped magnet surrounded by an electromagnetic coil. These magnets form a shaft 340 that houses the disk-shaped magnets described above. Typically, the disk-shaped magnets are arranged with like poles next to each other; that is, the orientation of the disk-shaped magnets is NS, SN, NS, etc., alternating along the stack. This shaft 340 is arranged to travel through a forcer 342.

[0125] Thus, forcer 342 includes an electromagnetic coil where passing a current through the coil induces a magnetic field that results in forcer 342 being pushed in a desired direction along shaft 340 .

[0126] The current through the coil is controlled to induce a varying magnetic field from the coil which, due to the permanent magnetic field from the disk-shaped magnet stack, causes actuation of the forcer 342 .

[0127] A forcer 342 is connected to the underside of each pillar 316, 318, 320. The pillars 316, 318, 320 have a number of bearings 344 that engage with bearing rails 346 that extend along the x-carriages 310a-310c in the x-direction. This allows the pillars 316, 318, 320 to move back and forth along the x-direction as the forcer 342 moves along the shaft 340.

[0128] Because of the fixed connection between the forcer 342 and the surrounding x-carriages 310a-310c (particularly the pillars 316, 318, 320), movement of the forcer 342 causes movement of the x-carriages 310a-310c (and thus the corresponding pillars 316, 318, 320) along the x-direction, as appropriate. Furthermore, as the pillars 316, 318, 320 are connected to the underside of the passenger carrier portion 304 (through their respective guide portions), movement of the forcer 342 causes movement of the passenger carrier portion 304 along the x-axis.

[0129] At each end of the travel of the x-carriages 310a-310c within the y-carriages 308a-308c there is a resilient bumper 348 (in this case a coil spring) which provides a "cushion" motion at the end of the travel of the x-carriages 310a-310c.

[0130] The undersides of the y-carriages 308a-308c have a number of further bearings 350 which engage bearing rails 352 on the respective bases 315 extending along the length that the y-carriages 308a-308c can travel (i.e. in the y-direction). The linear motors 312 of the y-carriages 308a-308c provide motion using a forcer including an electromagnetic coil running along a magnet track 313, in a conventional manner for U-channel linear motors known in the art. The linear motors 312 of the y-carriages 308a-308c move the y-carriages 310a-310c, and hence the x-carriages 310a-310c mounted thereon, along the y-axis. Due to the connections between the pillars 316, 318, 320 and the passenger carrier section 304, this also moves the passenger carrier section 304 along the y-axis.

[0131] Similar to the bumpers 348 described above, at each end of the travel of the y-carriages 308a-308c along the base 315 is a resilient bumper 349 (in this case a coil spring) which "cushions" the ends of the travel of the y-carriages 308a-308c.

[0132] Figure 18 is an isometric view of a motion platform 402 with a passenger carrier section 404 mounted on a stacked base, and an XY table stage 406 positioned on top of a yaw table stage 408, in accordance with one embodiment of the present invention. Figures 19A and 19B are further isometric views of the motion platform of Figure 18, showing a cutaway view of the monocoque passenger carrier section 404. Figure 20 provides a top view of the yaw table stage 408.

[0133] The "primary" XY table stage 406 of the motion platform 402 is of the same structure and functions in a similar manner as the arrangement described above with reference to Figures 13-17. However, rather than relying solely on the XY table stage 406 to provide yaw motion (i.e., rotation about the z-axis), the XY table stage 406 is mounted on a "secondary" yaw table stage 408 which is capable of providing unlimited yaw.

[0134] The yaw table stage 408 complements the XY table stage 406 to ensure that yaw travel remains both highly dynamic and unlimited. As long as the yaw table stage 408 can accelerate to its maximum speed in the time taken by the XY table stage 406 to reach its rotational limit, there should be no degradation in performance when these stages 406, 408 are mounted on top of each other.

[0135] As can be seen from the plan view of Figure 20, the yaw table stage 408 includes three concentric support rails 410 that act as bearing rails. The primary XY table stage 406 (not shown in Figure 20) includes a number of bearing blocks 412 that are arranged to move around the circumference of the concentric rails 410. For ease of illustration, only a selected number of the bearing blocks 412 are labeled in Figure 20.

[0136] These bearing blocks 412 are connected to the underside of a bed 414 which is positioned between the bearing blocks 412 and the XY table stage 406, which is attached to the bed 414, which is attached to the bearing blocks 412 of the yaw table stage 408. This structure can be made from steel, carbon or both.

[0137] The yaw table 408 includes a radial linear motor 416 that drives the rotational motion of the XY table stage 406 about the z-axis, i.e., provides the yaw motion, and the bearing block 412 slides on the rails 410 as the XY table stage 406 rotates. A forcer of the motor 416 is connected to the bed 414, while a stationary magnet of the motor 416 is connected to the base of the yaw table 408.

[0138] The number of bearing blocks 412 can be selected as a trade-off between stiffness and friction.

[0139] Thus, one skilled in the art will appreciate that embodiments of the present invention provide an improved motion platform having six degrees of freedom, where all motion is imparted through in-plane movement of the control pillars. The motion platform of the present invention can be easily scaled, for example in the surge direction, without requiring a substantial increase in the footprint of the motion platform. Furthermore, because out-of-plane motion is achieved only through in-plane motion of the control pillars, there is no need to stack layers of actuators, resulting in a lighter weight system that would typically exhibit improved frequency response compared to conventional motion platforms.

[0140] Stacking layers of actuators is not required, but this can still be beneficial while retaining the benefits of using fixed height control pillars. By stacking the actuators as separate carriages, position actuators can be mounted on top of other actuators and the moving mass may be kept below when used in large motion envelopes.

[0141] Although specific embodiments of the present invention have been described in detail, those skilled in the art will understand that the embodiments described in detail are not intended to limit the scope of the invention as claimed.

Claims

1. 1. A motion platform comprising: a base and a passenger carrier portion, the passenger carrier portion being linearly movable along mutually orthogonal first, second and third axes and rotationally movable about the first, second and third axes; the base comprises a first control pillar, a second control pillar, and a third control pillar each extending along the third axis, each of the first control pillar, the second control pillar, and the third control pillar being independently movable in the direction of the first axis and the second axis within a plane defined by the first axis and the second axis, and the first control pillar, the second control pillar, and the third control pillar being mechanically constrained to move only within the plane; the occupant carrier portion comprises a first guide portion, a second guide portion, and a third guide portion, the first guide portion, the second guide portion, and the third guide portion being pivotally connected to the first control pillar, the second control pillar, and the third control pillar, respectively, by respective coupling members; the first guide portion, the second guide portion, and the third guide portion are each angled non-parallel to a plane defined by the first axis and the second axis; the first guide portion, the second guide portion, and the third guide portion are each angled with respect to the other guide portions so as not to be parallel to the other guide portions; the guide portions restrain the movement of the respective coupling members along the guide portions; the motion platform is arranged, in use, such that the first control pillar, the second control pillar, and the third control pillar each have a respective height of a predetermined value along the third axis. Motion platform.

2. 2. The motion platform of claim 1, wherein the base comprises an X-Y table portion configured to provide independent in-plane movement of the first control pillar, the second control pillar, and the third control pillar along a respective first direction and a respective second direction, the first direction and the second direction defining a plane perpendicular to the third axis.

3. The motion platform of claim 2 , wherein the first direction is along the first axis and / or the second direction is along the second axis.

4. 3. The motion platform of claim 2, wherein the X-Y table portion comprises an X-Y table having a first slide rail and a second slide rail, the slide rails being slidably moveable relative to one another, and at least one control pillar mounted to the X-Y table such that sliding movement of the first slide rail moves the at least one control pillar along the first direction and sliding movement of the second slide rail moves the at least one control pillar along the second direction.

5. 3. The motion platform of claim 2, wherein the X-Y table portion comprises a first X-Y table, a second X-Y table, and a third X-Y table, each of the first X-Y table, the second X-Y table, and the third X-Y table comprising a respective first slide rail and a second slide rail, the slide rails being slidably movable relative to one another, and the first control pillar, the second control pillar, and the third control pillar are mounted to the first X-Y table, the second X-Y table, and the third X-Y table, respectively, such that sliding movement of the first slide rail moves the corresponding control pillar along the first direction, and such that sliding movement of the second slide rail moves the corresponding control pillar along the second direction.

6. Each of the first XY table, the second XY table, and the third XY table includes a first carriage and a second carriage, respectively, the first carriage and the second carriage being arranged in a stack; the first carriage comprises one or more bearings that move along the first direction relative to the first control pillar and the second carriage; and a first motor arranged to drive the first carriage to move along the first direction; the second carriage comprises one or more bearings for movement along the second direction relative to bases of the first XY table, the second XY table and the third XY table, and a second motor arranged to drive the second carriage to move along the second direction; the second carriage further comprises one or more bearing rails aligned along the first direction, the bearings of the first carriage engaging the one or more bearing rails of the second carriage; and the base of each of the first XY table, the second XY table and the third XY table comprises one or more further bearing rails aligned along the second direction, the bearings of the second carriage engaging the one or more bearing rails of the base; The motion platform of claim 5 .

7. The motion platform of claim 5 , wherein the first XY table, the second XY table, and the third XY table each comprise one or more coreless linear motors.

8. 2. The motion platform of claim 1, wherein the base comprises a circular support rail defining a plane perpendicular to the third axis, the first control pillar, the second control pillar, and the third control pillar connected to a plurality of radially movable actuators, each connection between the first control pillar, the second control pillar, and the third control pillar and a respective radially movable actuator provided by a respective tension member, the radially movable actuators configured to move around a circumference of the circular support rail.

9. The guide portion is the first guide portion is located at a front center portion of the passenger carrier portion, the second guide portion is located at a rear left portion of the passenger carrier portion, The third guide portion is disposed so as to be located at a rear right portion of the passenger carrier portion. The motion platform of claim 1 .

10. The motion platform of claim 1 , wherein each of the guide portions comprises a guide rail defining a trajectory along which movement of a respective one of the linkage members is constrained.

11. The motion platform of claim 1 , wherein one or more of the guide portions comprises a resilient member.

12. 2. The motion platform of claim 1, wherein the guide portions have a layout such that an angle between at least one of the guide portions and a plane defined by the first axis and the second axis is between 10 degrees and 70 degrees, preferably between 20 degrees and 60 degrees, and more preferably between 25 degrees and 55 degrees.

13. 2. The motion platform of claim 1, wherein the guide portions have a layout such that an angle between the first guide portion, the second guide portion, and the third guide portion is between 70 degrees and 150 degrees, preferably between 80 degrees and 140 degrees, and more preferably between 90 degrees and 135 degrees.

14. The motion platform of claim 13 , wherein an angle between the second guide portion and the third guide portion is approximately 100 degrees.

15. The base portion is a primary stage comprising an X-Y table portion configured to provide independent in-plane movement of the first control pillar, the second control pillar, and the third control pillar along a respective first direction and a respective second direction, the first direction and the second direction defining a plane perpendicular to the third axis; a secondary stage comprising a circular support rail, the support rail defining a plane perpendicular to the third axis; the XY table portion is mounted to the support rail via a radially movable bearing member configured to move around the circumference of the circular support rail; The motion platform of claim 1 , wherein the secondary stage further comprises a radial motor disposed to drive rotational movement of the primary stage relative to the secondary stage.

16. 2. The motion platform of claim 1, wherein movement of the first control pillar, the second control pillar, and the third control pillar in the direction of the first axis and the second axis is translated into out-of-plane movement in the direction of the third axis via the respective coupling members and the respective guide portions having an angled layout by positioning the first control pillar, the second control pillar, and the third control pillar to force the motion platform to move to a desired attitude.

17. The motion platform of claim 1 , wherein each linkage member is movable along each guide portion to tilt the passenger carrier portion.

18. 1. A motion platform comprising: a base and a passenger carrier portion, the passenger carrier portion being linearly movable along orthogonal first, second and third axes and rotationally movable about the first, second and third axes; the base portion comprises a first control pillar, a second control pillar, and a third control pillar each extending along a third axis, the first control pillar, the second control pillar, and the third control pillar each being linearly movable within a plane defined by the first axis and the second axis; the occupant carrier portion comprises a first guide portion, a second guide portion, and a third guide portion, the first guide portion, the second guide portion, and the third guide portion being pivotally attached to the first control pillar, the second control pillar, and the third control pillar, respectively, by respective coupling members, the first guide portion, the second guide portion, and the third guide portion each being angled non-parallel to the plane defined by the first axis and the second axis, a first control pillar, a second control pillar and a third control pillar arranged such that the first control pillar, the second control pillar and the third control pillar each have a respective height of a predetermined value along the third axis, the first control pillar, the second control pillar and the third control pillar being non-parallel to a plane, the first control pillar, the second control pillar and the third control pillar being non-parallel to the other guide portions, the motion platform being arranged such that, in use, the first control pillar, the second control pillar and the third control pillar each have a respective height of a predetermined value along the third axis, and by positioning the first control pillar, the second control pillar and the third control pillar to force the motion platform to move to a desired attitude, movement of the first control pillar, the second control pillar and the third control pillar in the directions of the first axis and the second axis can be converted into movement in the direction of the third axis.

19. a motion platform comprising a base and a passenger carrier portion, the passenger carrier portion being movable along and about orthogonal first, second and third axes; The base portion comprises a first control pillar, a second control pillar, and a third control pillar each extending at a predetermined height along the third axis, the first control pillar, the second control pillar, and the third control pillar each being independently movable in the directions of the first axis and the second axis, the occupant carrier portion is pivotally connected to the first control pillar, the second control pillar, and the third control pillar by respective coupling members, the motion platform comprises a first guide portion, a second guide portion, and a third guide portion, the first guide portion, the second guide portion, and the third guide portion being , each of the first guide portion, the second guide portion, and the third guide portion are angled relative to the other guide portions so as to be non-parallel to a plane defined by the first axis and the second axis, each of the first guide portion, the second guide portion, and the third guide portion are angled relative to the other guide portions so as to be non-parallel to the other guide portions, and each of the first guide portion, the second guide portion, and the third guide portion are angled relative to the other guide portions so as to be non-parallel to the other guide portions, and each of the coupling members is movable along each of the guide portions to tilt the occupant carrier portion.

20. 3. The motion platform of claim 2, wherein each of the first control pillar, the second control pillar, and the third control pillar are mounted on a respective XY table, each of the respective XY tables moving each of the first control pillar, the second control pillar, and the third control pillar in a plane.

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