Motion platform system

Abstract

A motion platform system includes a base, a platform movable relative to the base and allowing infinite yaw motion, the platform including an endless track following a closed curve to which a plurality of motors are movably connected. And the motor is connected to the platform through a push-pull rod. The motion platform system is an overdetermined motion platform system that includes one or more bases, a platform that is movable in six degrees of freedom and allows for infinite yaw motion. Four or more motors are movably connected to each endless track in the group of two endless tracks, wherein each motor is connected to the platform through a push-pull rod.

Description

Technical Field

[0001] The present invention relates to a motion platform system, which comprises a base, a platform that can move relative to the base and allows infinite rotational motion. The system consists of an endless rail along a closed curve, and a plurality of motors are movably connected to the rail. The motors are connected to the movable platform through push-pull rods. Background Art

[0002] WO2017 / 202920 describes a motion platform system comprising a base and a platform capable of moving relative to the base in 6 degrees of freedom. The base and the platform are connected by eight actuators. The system is considered to be overdetermined because the number of constraints (i.e., the length of each of at least eight actuators changes with the position of the joints on both sides) is greater than the number of degrees of freedom, i.e., the 6 degrees of freedom of the platform system.

[0003] A motion platform that can move relative to a base and allow infinite yaw motion as well as infinite rotational motion is known from US9109743. The publication describes a motion platform that can move along 6 degrees of freedom. Six motors that can run along a circular track are disclosed. Each motor is connected to the platform via a rod.

[0004] US2012 / 0286123 describes a motion platform capable of moving along 6 degrees of freedom and allowing unlimited yaw motion. Six brackets are each connected to a movable ring. The rings are stacked concentrically and can rotate independently of each other. The rotation of the rings is achieved by an externally positioned electric motor that meshes with the rings via a rack and pinion.

[0005] US6196081 describes a mobile platform capable of moving in 6 degrees of freedom. Six electric motors capable of running along one or more circular tracks are disclosed.

[0006] GB2585945 describes a motion platform system, which includes a base, a platform that can move relative to the base and allow infinite rotational motion. The system consists of an endless circular rail. In one embodiment, 6 motors are connected to the rail, wherein pairs of motors are connected to the control column by length-controllable actuators. By moving the control column in the xy plane, the platform moves in the z direction along a guide that is angled relative to the xy plane through a coupling. The angled guide rail leads to a fixed gearing. This embodiment requires 12 motors. In another embodiment, 9 motors are connected to the circular rail to control 3 control columns. A control column is connected to three motors by a cable with adjustable length. Therefore, each motor on the track is also equipped with a cable winding motor. Therefore, this embodiment requires 18 motors. The disadvantage of the motion platform system is that the number of motors is large, which makes the system complicated. Each motor requires a separate power supply unit, an encoder, and additional hardware such as cable wiring. In addition, the motors are used in series, which increases the complexity of the system control because the motors need to be adjusted in series with possibly different types of feedback sensors and different motor characteristics. The stacking of motors also seriously reduces the compliance of the entire control loop. Another disadvantage is that the use of angled guides leads to a fixed gear transmission between the heave movement and the control column movement. Summary of the invention

[0007] The advantage of a platform with infinite rotational motion is the ability to simulate long periods of motion in one direction. The disadvantages of prior art motion platforms are their complexity or their low stability and small workspace, making them less suitable for applications such as car driving simulation. The present invention aims to provide a simple motion system with greater stability that can be used to simulate a wide range of maneuvers in a larger workspace, with a higher bandwidth, thus providing a more realistic and accurate simulation of an actual vehicle driving on a road or track.

[0008] This is achieved by the following motion platform system. A motion platform system comprises a base, a platform that can move relative to the base and allows infinite rotational motion, the platform comprising an endless rail following a closed curve, a plurality of motors movably connected to the rail, wherein the motors are in turn connected to the platform via push-pull rods, The motion platform system is an overdetermined motion platform system, comprising one or more bases, a platform capable of moving along six degrees of freedom relative to the one or more bases and allowing infinite rotational motion, wherein two or more endless tracks having different diameters and following a closed curve are connected to the same base, or wherein one endless track following a closed curve is connected to a first base, and another endless track following a closed curve is connected to a second base, and wherein four or more motors are movably connected to each endless track, and wherein each motor is connected to the platform via a push-pull rod.

[0009] The applicant has found that the overdetermined motion platform has advantages over the motion platform system implemented with six motors described in the prior art publication US6196081 in terms of the ability to carry higher payloads, increase acceleration and / or higher stiffness. This further allows for a higher control bandwidth and a mechanically safe design, in which the platform does not collapse or contact the floor when the individual motors are at an extreme distance of separation. Further, a redundant system with one-fold redundancy, and in some cases even a redundant system with two-fold redundancy, is obtained. One-fold and two-fold redundancy means that when a motor or a push-pull rod fails, the remaining seven or corresponding six motors and / or push-pull rods can still fully control the platform and optionally bring the platform to a safe position. In addition, compared with a conventional six-motor system, the overdetermined system has advantages in increasing the available workspace of the simulator. Adding motors and rods as in the present invention will result in an overdetermined system and a smaller motion envelope. The applicant has found that despite this, the motion platform system of the present invention can still produce a larger and more symmetrical workspace while maintaining stability in a larger part of its motion envelope. This can be explained by the fact that by using two endless rails, the degrees of freedom of the platform, such as heave and roll, or pitch and sway, etc., can be decoupled between the rails, allowing greater simultaneous excursions of the platform in multiple degrees of freedom compared to prior art systems.

[0010] The motion platform of the present invention reduces complexity because it uses eight similar motors. In addition, one motor directly moves one push-pull rod, thereby avoiding the series connection of the motor and the actuator or the motor and the cable. This is much less than the number of motors described in the previously referenced prior art publication GB2585945. Further, the platform system has a variable transmission device depending on the platform posture. By pre-positioning the platform, more acceleration or speed performance can be utilized, which is unlikely in the platform of the prior art publication GB2585945.

[0011] Additionally, one or more additional motor-rod combinations or combinations can be used to select a force distribution between the motor-rod combinations from an infinite solution space where there is a force fight. This can be used to apply a preload on the push-pull rods. This preload can avoid the so-called zero force crossing in the push-pull rods. This can prevent backlash through mechanical components. By avoiding motion through backlash of certain components, the nonlinearity of the motion platform system stiffness can be reduced. This achieves a greater control bandwidth.

[0012] The one or more bases are fixed elements that are usually connected directly or indirectly to the ground. The base can be a vertical wall to which one or more endless tracks are connected. The base can also be two spaced vertical walls, each connected to an endless track. The endless tracks connected to the vertical walls will then run in a substantially vertical plane. The infinite rotation can then be an infinite roll or infinite pitch motion.

[0013] The base can also be two spaced apart horizontal fixed elements, such as a base directly connected to the floor and a base to the ceiling as spaced apart bases. The endless track connected to the floor base and the ceiling base will then run in a substantially horizontal plane. Preferably, a single base connected to the floor is used, to which the two endless tracks are connected. When such a base or bases are used, the infinite rotation will be an infinite yaw motion.

[0014] The motion platform can be described by a set of mathematical equations, where the number of equations matches the number of constraints. For this system, the number of constraints will be eight or more, which is equal to the number of movable motors along one or more endless rails or rails. For the motion platform system of the present invention, the number of equations is six due to the six degrees of freedom. The system is overdetermined because the number of constraints is greater than the number of degrees of freedom. Such an overdetermined system may have multiple mathematical solutions for a single motion, while a determined system always has a single mathematical solution for a given motion.

[0015] The motion of a motion platform is defined by the six degrees of freedom of the platform system. Platform motion is generated by changing the positions of the motors. Since the system has more motors than degrees of freedom, as the individual motor positions change, force imbalances are created in the system due to limitations in sensor accuracy, mechanical misalignments, losses in drives, joint friction, and other properties of the motion platform and its control system.

[0016] The result of an overdetermined system is that, depending on the orientation of the eight or more motors relative to the platform, there is a pattern of opposing push-pull rod forces that only deform the platform. This is known as a force-fight. To avoid or minimize such force-fights, preferably the motion platform system is provided with a controller that (a) is configured to adapt the desired platform motion set point to the commanded platform motion set point, (b) is configured to move the eight or more motors to achieve the commanded platform motion set point, and (c) is configured to dynamically redistribute the forces exercised on the platform between the motors by the motors and their connected push-pull rods.

[0017] The commanded and desired platform motion setpoints may be platform position setpoints.Preferably, the commanded and desired platform motion setpoints are commanded and desired setpoints for platform position, velocity and acceleration.

[0018] The desired platform motion setpoint may be an output of a simulation program or a host computer such as a driving simulator or a flight simulator. The desired motion setpoint may be provided directly from the simulation program or host computer, or may be the output of a motion cue filter. Such a motion cue filter may minimize motion that does not contribute to the desired motion cue experience.

[0019] The controller, and in particular part (c) of the controller, is based on locally linearized equations of motion for the motion platform system. The stability of the controller may be unfavorable outside the performance limits due to the nonlinearity of the system outside the performance limits. Further, external forces, such as end stop damping forces, may act on motors that are not modeled or are incorrectly timed. For these reasons, it is preferred to use a controller that includes a guidance module that is configured to adapt the required platform motion set point to the commanded platform motion set point by a reverse motion (also called an additional corrective motion) and is configured to calculate a force opposition set point, wherein the reverse motion and force opposition set point are derived from a model predictive control algorithm using a cost minimization control strategy. The platform system suitably has predetermined performance limits including platform and motor domain limits, wherein the model predictive control algorithm uses a cost minimization control strategy that is configured to keep the system within its platform and motor performance limits.

[0020] The counter-movement of the platform is intended to keep the platform and the motor within performance limits. The generation of a force antagonism set point results in a better load balance between the push-pull rods, so that the motor current limit is not exceeded, or so that the motor current is optimized. In most cases, the force antagonism set point may be zero. For example, when the individual push-pull rods exceed a predetermined force and / or when the individual motors and push-pull rod combinations have predetermined and defined speed and force antagonism set points close to zero, the force antagonism set point may deviate from zero. It has been found that when the individual motors and push-pull rod combinations have speed and force set points close to zero, an unstable system may be obtained, which may cause undesirable vibrations. By allowing a small force antagonism, such undesirable vibrations can be avoided.

[0021] The number of motors for the overdetermined system of the present invention is eight or more. On top of the eight motors, one, two or more motors may be added on each or both endless tracks. These additional motors are preferably connected to the platform via push-pull rods. Additional motors may also be present on a third or even fourth additional endless track connected to the same one or more bases. Such additional motors may be useful to further increase the forces that can be applied on the platform. Preferably, there are two endless tracks with four motors movably connected to each endless track. This is advantageous because it introduces minimal complexity to the system.

[0022] An endless track is defined as a motor that can move in two directions along a preferably closed curve in a plane. In this way, the motor can move from a starting position in one direction and return to its starting position. The closed curve shape can be oval, preferably elliptical, more preferably circular. Small deviations from a circular shape may occur.

[0023] Eight or more motors may be present on two endless tracks. Preferably, there are eight motors on the two endless tracks, four of which are movably connected to the first endless track and the remaining four motors are movably connected to the second endless track. In a further preferred embodiment, the eight motors are movably connected to two circular endless tracks having centers, wherein the two endless tracks run in the same plane or parallel planes. A common axis passes through the two centers in a direction perpendicular to one or more planes (the plane or planes). When the two circular tracks have different diameters and are connected to the same base, an inner track and an outer track are defined. Then, the inner track or its vertical projection will run appropriately within the outer track. Then, four or more motors are movably connected to the inner track and four or more motors are movably connected to the outer track.

[0024] In a first embodiment, a motion platform system having an inner annular track and an outer annular track is connected to a single base. Suitably, the distance between the single base and the plane on which the inner track runs is greater than the distance between the base and the plane on which the outer track runs. This reduces the chance of a push-pull rod connected to a motor running on the inner track colliding with a push-pull rod connected to a motor running on the outer track.

[0025] In a second embodiment of the motion platform system, two endless tracks are connected to two separate bases. The base consists of a first base and a second base. The movable platform is located between the first base and the second base, the first base is connected to the first endless track, and the second base is connected to the second endless track. The first base can be, for example, a floor, and the second base can be a ceiling of a building or a frame connected to the floor. Such an embodiment is advantageous because it avoids collisions between rods, will have a larger working space and is more stable.

[0026] Eight or more motors are individually connected to the platform via push-pull rods. Eight or more push-pull rods are appropriately connected to the platform at spaced locations on the platform to enable the platform to move. Preferably, there are four spaced connection areas on the platform, wherein in each area, two rods are connected to the platform. These first, second, third and fourth areas on the platform are preferably oriented relative to each other in that an imaginary line connecting the first and third areas intersects an imaginary line connecting the second and fourth areas directly or in their projections on the platform.

[0027] Preferably, these lines intersect each other perpendicularly. Preferably, the distance between the first connection area and the third connection area is smaller than the distance between the second connection area and the fourth connection area. This can be achieved by providing a platform of rhombus shape, wherein the first connection area, the second connection area, the third connection area and the fourth connection area of ​​the platform are located at the corners of the rhombus. Such a platform is suitably provided with a seat for a driver, which seat defines a driving direction for the driver, which driving direction coincides with the line extending from the second connection area and the fourth connection area. By having a simulated driving direction along this longer line, the motion platform workspace is optimized for applications such as motorsport driving simulators by having an improved field of view.

[0028] For the first and second embodiments described above, the platform suitably has the above-mentioned four connection areas, which are spaced apart from each other on the platform, wherein Two adjacently positioned motors on a first of the two endless tracks are each connected to a second connection area of ​​the platform via a push-pull rod, The remaining two adjacently positioned motors on the first endless track are each connected to a fourth connection area of ​​the platform via a push-pull rod, and Two adjacently positioned motors on a second of the two endless tracks are each connected to a first connection area of ​​the platform via a push-pull rod, The remaining two adjacently positioned motors on the second endless track are each connected to the third connection area of ​​the platform via a push-pull rod. This arrangement allows large combined surge and sway motions while maintaining stability and avoiding collisions between the push-pull rods.

[0029] The push-pull rod is a rigid element. Preferably, the push-pull rod is made of a light, high-rigidity material, such as a metal alloy, more preferably carbon fiber.

[0030] The push-pull rod is connected to the motor at one end and to the platform at the other end. One motor is connected to the platform through a single push-pull rod. The connection between the push-pull rod and the motor and between the push-pull rod and the platform allows the platform to move in 6 degrees of freedom. The connection is achieved through joints. When the platform requires certain surge and sway excursions, joints with a wide range of motion are required. In addition to the joint range, the joint preferably has sufficient joint stiffness.

[0031] Preferably, the push-pull rod is connected to the motor via a lower joint having two or more degrees of freedom. Possible examples of joints include ball joints, universal joints, and flexible joints. Preferred combinations of upper and lower joints are two ball joints, a ball joint and a universal joint, and two universal joints. If universal joints are used for both the lower joint and the upper joint, additional degrees of freedom should be added. This can be achieved by rotatably connecting the rod to one or both of the joints, wherein the rotation is performed along the axis of the rod. The push-pull rod may also include a flexible element to provide off-axis compliance while maintaining an axially rigid structure. Alternatively, the push-pull rod may include two aligned rod portions, wherein one portion of the rod can rotate along a common axis relative to the other portion of the rod via a central bearing assembly.

[0032] Preferably, the lower and upper joints are universal joints with double sided suspension. When larger deflections are required, it is preferred to use an upper joint consisting of an axle suspended on one side, for example with two preloaded bearings. Both bearings are suitably mounted in a bearing housing integrated in the frame of the mobile simulator at the connection area. A single-sided suspension allows a wider range of motion than a double-sided suspended axle. In the connection area of ​​the platform, there may be two joints. The axles of the two joints are preferably positioned parallel to each other.

[0033] The push-pull rod is preferably rotatably connected to the lower joint and / or the upper joint. Rotational connection means that the rod itself can rotate along its own axis relative to one or both of the lower head and the upper joint. This is advantageous because a certain amount of flexibility can be added to the push-pull rod assembly, thereby achieving greater workspace utilization within the motion system envelope.

[0034] The motor may be an electric motor movably connected to the track via a rack and pinion. Examples of such connections are described in CN107317446, WO2019 / 192228, and US6196081.

[0035] Preferably, the motor is a linear motor, also known as a linear electric motor. A linear motor comprises a movable armature that interacts with a fixed magnetic track present in an endless track. Through the magnetic interaction between the armature and the magnets, the motor is able to move along the endless track.

[0036] The linear motor may be an iron core or air core linear electric motor. The linear motor is preferably provided with two coil packages connected to the motor by structural members. In a preferred configuration, permanent magnets are mounted on the inner and outer surfaces of the vertical tubular section. The two coil packages extend downward from the linear motor so that one coil package faces the magnet on the radial outer surface of the vertical tubular section and the other coil package faces the magnet on the radial inner surface of the vertical tubular section. In this configuration, one coil package of the movable motor is therefore directly next to the magnet mounted on the inner surface of the tubular section and the second coil package is directly next to the magnet mounted on the outer surface of the vertical tubular section. This double-sided design keeps the linear motor compact and efficient while minimizing vibration and balancing the attraction of the magnet to the coil package. A compact motor is advantageous because it results in a smaller arc length on the endless track, thereby increasing the available excursion of the motor and push-pull rod combination.

[0037] In an alternative configuration, the linear motor is provided with 2 coil packages connected by a structural member so that one coil package is located above the permanent magnet of the fixed magnet present in the endless track and the other coil package is located below the permanent magnet of the fixed magnet present on the endless track.

[0038] The motion platform of US9109743 has a rotor as part of a circular track, which has the problem that a dedicated servo drive is required to control the motor. Therefore, it is preferred that the endless track comprises an endless track portion of permanent magnets, an endless bracket guide portion and an endless support track portion, to which the support bracket is movably connected. The linear motor is movably and functionally coupled to the endless track comprising permanent magnets. The linear motor is connected to the support bracket and supported on the support track by track rollers.

[0039] The endless carriage rail preferably runs radially outside the endless track portion of the permanent magnets.The endless support rail preferably runs radially inward from the endless track portion of the permanent magnets and may run in the same or different plane as the endless track portion of the permanent magnets.

[0040] The linear motors are powered and controlled by electric current. Therefore, each linear motor is preferably connected to a power distribution and control unit by a cable. Such a power distribution and control unit is suitably positioned in a space surrounded by one or more endless rails or rails. The space surrounded by one or more endless rails is the space below or above the platform, located within an imaginary column extending vertically from one or more endless rails. Preferably, the power distribution and control unit is suitably positioned on a base below or above the platform and is located within one or more endless rails. In order to achieve infinite yaw motion of the platform, the power distribution and control unit can be moved on the base to allow infinite yaw motion.

[0041] The present invention also relates to the following motion platform system, comprising one or more bases, a platform capable of moving along six degrees of freedom relative to the one or more bases and allowing infinite yaw motion, wherein one or more endless tracks following a closed curve are connected to the one or more bases, wherein six or more motors are movably connected to the one or more endless tracks, wherein each motor is connected to the platform by a push-pull rod, wherein a power distribution and control unit for the six or more motors is present in a space surrounded by the endless tracks, wherein the power distribution and control unit is individually connected to each of the six or more motors by one or more cables, wherein the power distribution and control unit is movable to allow infinite yaw motion.

[0042] In the above embodiments, the power distribution and control unit is suitably positioned on a base below or above the platform and is located within one or more endless tracks. In order to achieve infinite yaw movement of the platform, the power distribution and control unit can be moved on the base to allow infinite yaw movement. The one or more bases are suitably one or two bases of the main invention as described above. The one or more endless tracks are preferably one or two endless tracks. Examples of suitable embodiments comprising two endless tracks with one or more bases are those described for the present invention. DETAILED DESCRIPTION

[0043] The invention will be illustrated using the following non-limiting drawings.

[0044] Figure 1A motion platform system (1) is shown, comprising a base (2) and a platform (3) capable of moving relative to the base (2) and allowing infinite yaw motion. The motion platform system (1) is provided with eight linear motors (6), each of which is connected to the platform (3) via a push-pull rod (7). The platform (3) shown is capable of moving relative to the base (2) in 6 degrees of freedom and is overdetermined due to the presence of eight push-pull rods (7).

[0045] An inner circular endless track (4) and an outer circular endless track (5) are connected to the base (2). The inner endless track (4) and the outer endless track (5) are positioned concentrically relative to each other. As shown in the figure, the distance between the base (2) and the plane on which the inner endless track (4) runs is greater than the distance between the base (2) and the plane on which the outer endless track (5) runs.

[0046] Two adjacent motors (6) on the inner endless track (4) are each connected to a first connection area (8) of the platform (3) via a push-pull rod (7). The two remaining adjacent motors (6) on the inner endless track (4) are each connected to a third connection area (9) of the platform (3) (partially hidden by the platform (3)) via a push-pull rod (7). The two adjacent motors (6) on the outer endless track are each connected to a second connection area (10) of the platform (3) via a push-pull rod (7), and the two remaining adjacent motors on the outer endless track (5) are each connected to a fourth connection area (10) of the platform (3) via a push-pull rod (7). The platform (3) shown has a rhombus shape, wherein the first connection area (8), the second connection area (10), the third connection area (9) and the fourth connection area (11) of the platform (3) are located at the corners (12) of the rhombus.

[0047] Furthermore, a power distribution and control unit (13) is shown in the space (14) enclosed by the inner endless track (4). The power distribution and control unit (13) is movable, thereby allowing infinite yaw movement. Between the power distribution and control unit (13), cables can be extended through openings (15) in the platform (3) and push-pull rods (7) to each motor (6).

[0048] Figure 2 Shows Figure 1 The motion platform is shown, except that the inner endless track is now positioned above the platform (3) as a first endless track (16) and connected to a second base (18). Figure 1 The outer endless track (5) in is now the second endless track (19) connected to the first base (17). For the sake of clarity, the bases (17) and (18) are drawn schematically. The dimensions of the first and second endless tracks (16, 19) are as follows Figure 1 shown.

[0049] The two adjacent motors (6) on the first endless track (16) are connected to the first connection area (8) of the platform (3) via a push-pull rod (7). The two remaining adjacent motors (6) on the first endless track (16) are connected to the third connection area (9) of the platform (3) via a push-pull rod (7). The two adjacent motors (6) on the second endless track (19) are connected to the second connection area (10) of the platform (3) via a push-pull rod (7), and the two remaining adjacent motors (6) on the second endless track (19) are connected to the fourth connection area (11) of the platform (3) via a push-pull rod (7). For the sake of clarity, Figure 2 The power distribution and control unit are not shown.

[0050] Figure 3 and Figure 4 A linear motor (6) is shown which is movably connected to an endless track (5). The endless track (5) has an endless track portion (20) with a permanent magnet (20a), an endless bracket guide portion (21), and two support brackets (22) (one of which is visible) are movably connected to the endless bracket guide portion (21). The endless bracket guide portion (21) and its bracket support the linear motor (6) at their radially outer ends. The linear motor (6) is movably and functionally coupled to the endless track portion (20) with a permanent magnet. The linear motor is provided with two coil packages (24a, 24b), which are connected by a structural member (25) so that one coil package (24a, 24b) is located above the permanent magnet (20a) of the fixed stator and the other coil package is located below the permanent magnet (20a). The linear motor (6) is connected to the two support brackets. A circulating ball (27) is installed in the support bracket.

[0051] The guide rail portion (21) guides the motor along the endless track (5). The guide rail portion (21) is located radially outside the endless track portion (20) of the permanent magnet (20a). The linear motor (6) is also supported on the radial inside thereof by track rollers (26a, 26b) on the support rail (23). The track rollers (26a, 26b) are connected to the motor by arms (28) extending downwardly. In this way, the arms and track rollers provide additional vertical support for the linear motor (6). The support rail (23) can be a hardened and precision ground ring. Not shown, but preferably some kind of positioning measurement is provided for the motor. This can include read strips present on the endless track and a read head present as part of the motor. The read head is positioned to be able to detect the read strips and determine the position of the motor on the endless track.

[0052] Figure 3 Also shown is a universal joint as lower joint (30) having a lower fork (29) bolted to the electric motor (6). Figure 4 Only a portion of the lower fork (29) is shown. The lower joint shaft (31) passes through the lower fork (29). In the vertical direction, the pin (32) passes through the lower joint shaft (31). The pin (32) is connected at its end to a rod fork (33), which is rotatably connected to the lower end of the push-pull rod (7), allowing the push-pull rod (6) to rotate along its axis relative to the rod fork (32).

[0053] Figure 5 A universal joint pair is shown as an upper joint (34) at a connection region (11) consisting of a fork (35), a pin (36) and a shaft (37). The upper end of the push-pull rod (7) consists of a fork (35). The pin (36) passes through the fork (35) and rotatably fixes the end of the shaft (37). The shaft (37) is suspended in a bearing housing which is part of the connection region (11). Figure 3 This design allows a wider range of motion than when a universal joint is used as the upper joint.

[0054] Figure 6 Shows Figure 1 A motion platform system (1) is provided with a seat (38) for a driver (39), and a driving direction (40) is defined for the driver, the driving direction (40) being consistent with a line (41) extending from the second connection area (10) and the fourth connection area (12). An imaginary line (41) connecting the second connection area (10) and the fourth connection area (12) intersects an imaginary line (42) connecting the first connection area (8) and the third connection area (9) directly or perpendicularly in their projection on the platform (3). The distance between the first connection area (8) and the third connection area (9) is smaller than the distance between the second connection area (10) and the fourth connection area (11). The platform (3) shown has a rhombus shape, wherein the first connection area (8), the second connection area (10), the third connection area (9) and the fourth connection area (11) of the platform (3) are located at the corners (12) of the rhombus.

[0055] Figure 7 and Figure 8 An alternative design is shown in which the linear motor (6) is movably connected to the endless track (5). Figure 7 is a three-dimensional view of a portion of the endless track (5), showing the motor (6). Figure 8 yes Figure 7A cross section of an endless track (5) and a motor (6). Permanent magnets (43, 44) are mounted on the inner and outer surfaces of a vertical tubular portion (45) as an endless track portion of the permanent magnets. An outer tubular support portion (46) exists on the radially outer side of the vertical tubular portion (45) as an endless bracket guide portion. An inner tubular support portion (47) exists on the radially inner side of the vertical tubular portion (45) as an endless support track portion. All three tubular portions form an endless track (4, 5) and are connected to a base (2). A linear motor (6) is movably connected to the outer tubular support portion (46) and the inner tubular support portion (47). The motor (6) is connected to the outer tubular support portion (46) via a support bracket (48) which is part of the motor and a guide rail (48a) existing at the upper end of the outer tubular portion (46). The motor (6) is connected to the inner tubular support part (47) via a downwardly extending arm (49c) through track rollers (49a, 49b), which move along a horizontal support track (50) mounted on the upper end of the inner tubular support part (47). The motor is also provided with two coil packs (51a, 51b), which extend downwardly from a bracket base (52) which is part of the motor (6), so that one coil pack (51a) faces the magnet (43) on the radial outer surface of the vertical tubular part (45) and the other coil pack (51b) faces the magnet (44) on the radial inner surface of the vertical tubular part (45). A portion of the push-pull rod (7) and the lower joint (30) of the universal joint are shown as being present in the bearing housing (53). For the sake of clarity, Figure 8 The cross-sectional details of the lower joint (30) are not shown.

[0056] Fig. 9 Explained based on Figure 1 How the controller of the platform system (1) communicates with the eight linear motors (6). The host computer generates the desired platform motion set points at the platform position, velocity and acceleration. This set point can be adjusted by an optional motion cue filter to obtain a filtered set point (not shown). The controller is divided into two elements, namely the guidance law and the control law. The guidance law accepts the desired platform motion set points of platform position, velocity and acceleration from the external host computer. The desired set points are converted into commanded set points of platform position velocity and acceleration, as well as force opposition set points for the linear motors. The guidance law is designed so that when moving the platform (3) according to these set points, no operational or physical limitations are exceeded.

[0057] Fig. 9 The purpose of the control law is to move the motion platform to the commanded set point (3) as commanded by the guidance law. Figure 1The platform system can be described as a multi-channel (i.e. multiple degrees of freedom), overdetermined system (more motors than degrees of freedom) that is highly cross-coupled. The control law (CL) is designed as a multi-input multi-output controller with feedforward and feedback paths, which is designed to decouple the cross-coupling between the degrees of freedom and deal with the force opposition problem caused by more actuators than degrees of freedom. This is further described in WO2017 / 202920 for an overdetermined motion system including actuators.

Claims

1. A motion platform system comprising a base, a platform capable of moving relative to the base and allowing infinite rotational motion, the platform comprising an endless track following a closed curve, a plurality of motors movably connected to the endless track, wherein the motors are in turn connected to the platform by push-pull rods, The motion platform system is an overdetermined motion platform system, which includes one or more bases, a platform that can move along 6 degrees of freedom relative to the one or more bases and allows infinite rotational motion, wherein two endless tracks with different diameters and following a closed curve are connected to the same base, or wherein one endless track following a closed curve is connected to a first base, and another endless track following a closed curve is connected to a second base, and wherein four or more motors are movably connected to each endless track, and wherein each motor is connected to the platform via a push-pull rod.

2. The motion platform system of claim 1, wherein the infinite rotational motion is an infinite yaw motion.

3. The motion platform system according to any one of claims 1-2, wherein the one or more endless tracks have a circular shape.

4. A motion platform system according to any one of claims 1-3, wherein the two endless tracks are circular endless tracks having a center, and wherein the two endless tracks run in the same plane or in parallel planes, and wherein a common axis passes through the two centers in a direction perpendicular to one or more planes.

5. A motion platform system according to claim 4, wherein the platform is capable of moving along six degrees of freedom relative to a single base, wherein two endless tracks with different diameters define an inner track and an outer track, and wherein the distance between the single base and the plane in which the inner track runs is greater than the distance between the base and the plane in which the outer track runs.

6. The motion platform system according to any one of claims 1 to 4, wherein: One endless track following a closed curve is connected to a first base, another endless track following a closed curve is connected to a second base, and wherein the movable platform is positioned between the first base and the second base.

7. The motion platform system of any one of claims 1-6, wherein there are two endless tracks, and wherein four motors are movably connected to each endless track.

8. The motion platform system of any one of claims 1 to 7, wherein the platform has four connection areas spaced apart from each other on the platform, and wherein Two adjacently positioned motors on a first of the two endless tracks are each connected to a second connection area of ​​the platform via a push-pull rod, The remaining two adjacently positioned motors on the first endless track are each connected to a fourth connection area of ​​the platform via a push-pull rod, two adjacently positioned motors on a second of the two endless tracks are each connected to a first connection region of the platform via a push-pull rod, and The remaining two adjacently positioned motors on the second endless track are each connected to the third connection area of ​​the platform via a push-pull rod, and in, An imaginary line connecting the first end and the third end intersects an imaginary line connecting the second end and the fourth end directly or in their projections on the platform.

9. The motion platform system according to claim 8, wherein: An imaginary line connecting the first connection region and the third connection region perpendicularly intersects an imaginary line connecting the second connection region and the fourth connection region.

10. The motion platform system according to claim 9, wherein: The distance between the first connection region and the third connection region is smaller than the distance between the second connection region and the fourth connection region.

11. The motion platform system of claim 10, wherein the platform has a rhombus shape, and wherein the first connection area, the second connection area, the third connection area, and the fourth connection area of ​​the platform are located at corners of the rhombus.

12. The motion platform system according to any one of claims 10-11, wherein the platform is provided with a seat for a driver, the seat defining a driving direction for the driver, the driving direction being consistent with a line extending from the second connection area and the fourth connection area.

13. The motion platform system according to any one of claims 1 to 12, wherein: A push-pull rod connecting the motor to the platform is connected to the motor via a three-degree-of-freedom lower joint and to the platform via a two-degree-of-freedom upper joint, or wherein the push-pull rod connecting the motor to the platform is connected to the motor via a two-degree-of-freedom lower joint and to the platform via a three-degree-of-freedom upper joint.

14. The motion platform system of any one of claims 1-13, wherein the motor is a motor movably connected to the track via a rack and pinion.

15. The motion platform system of any one of claims 1-14, wherein the motor is a linear electric motor.

16. A motion platform system according to claim 15, wherein the endless track includes an endless track portion of permanent magnets, an endless bracket guide portion, and an endless support track portion, a support bracket is movably connected to the endless bracket guide portion, and wherein the linear motor is movably and functionally engaged to the endless track including permanent magnets, wherein the linear motor is connected to the support bracket and supported on the support track by track rollers.

17. The motion platform system according to claim 16, wherein: The permanent magnet is mounted on the inner and outer surfaces of the vertical tubular portion, wherein the endless bracket rail portion is an outer tubular support portion present on the radial outside of the vertical tubular portion, wherein the endless support track portion is an inner tubular support portion present on the radial inside of the vertical tubular portion, and wherein two coil packages extend downward from the linear motor such that one coil package faces the magnet at the radial outer surface of the vertical tubular portion and the other coil package faces the magnet at the radial inner surface of the vertical tubular portion.

18. The motion platform system according to any one of claims 14 to 17, wherein: A power distribution and control unit for eight or more motors resides in a space surrounded by the endless track, wherein the power distribution and control unit is individually connected to each of the eight or more motors by one or more cables, and wherein the power distribution and control unit is movable, allowing unlimited yaw motion.

19. The motion platform system according to any one of claims 1 to 5 or claims 7 to 18, wherein: Two endless tracks with different diameters and following a closed curve are connected to the same base, thereby defining an inner track and an outer track, and wherein one or more cables connect four motors movably connected to the outer track with a power distribution and control unit, and wherein one or more cables extend from each motor via a push-pull rod connecting the motor to the platform, and from the platform to the power distribution and control unit.

20. The motion platform system of claim 19, wherein the power distribution and control unit is movably positioned on a base, allowing unlimited yaw motion.

21. A motion platform system comprising one or more bases, a platform capable of moving relative to the one or more bases in six degrees of freedom and allowing infinite yaw motion, wherein: One or more endless tracks following a closed curve are connected to the one or more bases, wherein six or more motors are movably connected to the one or more endless tracks, wherein each motor is connected to the platform by a push-pull rod, and wherein a power distribution and control unit for the six or more motors is present in a space surrounded by the one or more endless tracks, wherein the power distribution and control unit is individually connected to each of the six or more motors by one or more cables, and wherein the power distribution and control unit is movable, allowing infinite yaw motion.

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