Patent ID: 12205494

References in this specification to particular orientations and positions, such as upper or lower refer to those orientations or positions as shown in the accompanying drawing.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

Motion System Including a Motion Generator

A motion system1including a motion generator2in accordance with a first aspect of the invention is shown inFIGS.1to19. The motion system1comprises a motion generator2mounted on a surface4, and supports a vehicle chassis3, which, in this embodiment, constitutes the payload of the motion generator2, and control means (for example as described in relation toFIG.26) above a frame5. The frame5has a generally triangular shape and is constructed of a lightweight rigid material such as aluminium. Other shapes and types of frames, such as space frames, and other materials are contemplated for use in such frames. In the embodiment shown, the chassis3is a replica of a racing car cockpit. The chassis3is supported by pairs of elongate rigid rods or struts,11,12;13,14; and15,16which at their upper ends are connected by upper joints11UJ,12UJ,13UJ,14UJ,15UJ, and16UJ respectively to the chassis3. The elongate rigid rods11-16may be made, for example, of carbon fibre to reduce resonance. The upper joints11UJ-16UJ may be spherical, cardan, or universal joints, and/or may comprise flexures. The lower end of each elongate rod11-16is connected by a lower joint11LJ,12LJ,13LJ,14LJ,15LJ, and16LJ respectively to an associated rocker11R,12R,13R,14R,15R, and16R, respectively which are arranged for pivotal movement on the inside of the triangular frame5of the motion generator2. The lower joints11LJ-16LJ may also be spherical, cardan or universal joints, and/or may comprise flexures. Linear actuators11LA-16LA which may be, for example, belt drives, linear motors (a suitable example of which would be an I-Force Ironless Linear Motor by Parker) or ball screw-driven actuators (a suitable example of which would be a PC Series Actuator by Thomson driven by an AKM2G Servo Motor by Kollmorgan). Belt drives are preferred. The connection between the rockers11R-16R and the linear actuators11LA-16LA is shown in more detail inFIGS.4-7.

It is contemplated that a motion generator in accordance with the invention may not include a frame5. In such an arrangement, at least some of, or all, the rockers and/or actuators could be mounted directly on the surface4rather than to a frame. Such a motion generator may be advantageous in that the surface may be more rigid than the frame. The frame has the advantage that it can be used to carry the entire the motion generator, particularly when it is used as a secondary motion generator in series with a primary motion generator.

FIGS.4and5show rocker16R and connected elements in more detail. The continuous toothed belt B connects with the rocker16R via rounded elements E which reduce wear on the connected belt B. An example of a suitable toothed belt is a Conti® Synchrochain Carbon belt made by Continental. InFIGS.4and5, the elements E are circular. InFIG.6, the corresponding elements E are curved. It should be noted that the belt B shown inFIG.6is spaced away from the curved elements simply for clarity, in practice the belt will closely fit to the curved elements. The toothed belts B pass around drivable correspondingly toothed electrically powered capstans (indicated as “C”). A suitable example of an electrically-powered capstan would be a synchronous belt sprocket by Martin, driven by an AKM2G Servo Motor by Kollmorgan. The capstans C operate under the control of a control system (for example as described in relation toFIG.26).

It will also be noted that the passive tension elements P in the embodiment ofFIGS.4and5are bungees or springs. In the embodiment shown inFIGS.6and7, the passive tension elements are compression springs. The belt B passes round freely rotating pulleys marked as P which are tensioned by the passive tensioning devices PT which provide a preload tension on a connected rocker11R-16R against the belt B connected to that rocker. By movement of one or more of the rockers11R-16R driven by the associated belts B and capstans C under the control of the control system, the rods or struts11-16move the chassis4, at high bandwidth in any of six degrees of freedom into a wide variety of conditions, some of which are described below.

The motion generator2, is particularly compact in a vertical direction. This compactness is advantageous when the motion generator is included in a motion system used in driving simulators.

In the following description, the position of the rockers11R-16R in use is described in more detail. For simplicity, only the position of the rockers11R-16R is described, and those rockers identified in the drawings with other elements unnumbered in some drawings. It will be appreciated by the skilled addressee that the other elements, such as the elongate struts11-16, belt drives, and connected passive tension devices will also be affected by movement of the rockets but this is not described in detail in the description below in relation toFIGS.1to3and7-17.

The motion generator2is shown with the chassis3in a neutral condition inFIGS.1to3. In this condition, the state of the rockers is as follows:

RockerPosition from below11RNeutral12RNeutral13RNeutral14RNeutral15RNeutral16RNeutral

The motion generator is shown with the chassis3in a surge forward condition inFIGS.8and9. In this condition, the states of the rockers is as follows:

RockerPosition from below11RAnti-clockwise12RAnti-clockwise13RNEUTRAL14RNeutral15RCLOCKWISE16RCLOCKWISE

The motion generator is shown with the chassis3in a sway left condition inFIG.10andFIG.11. In this condition, the position of the rockers is as follows:

RockersPosition from below11RCLOCKWISE12RCLOCKWISE13RANTI-CLOCKWISE14RANTI-CLOCKWISE15RCLOCKWISE16RCLOCKWISE

The motion generator is shown with the chassis3in a heave up condition inFIG.12andFIG.13. In this condition, the position of the rockers is as follows:

RockerPosition (from below)11RCLOCKWISE12RANTI-CLOCKWISE13RCLOCKWISE14RANTI-CLOCKWISE15RCLOCKWISE16RANTI-CLOCKWISE

The motion generator is shown with the chassis3in a roll right side down condition inFIG.14andFIG.15. In this condition, the position of the rockers is as follows:

RockerPosition (from below)11RCLOCKWISE12RANTI-CLOCKWISE13RNeutral14RNeutral15RANTI-CLOCKWISE16RCLOCKWISE

The motion generator is shown with the chassis3in a pitch nose down condition inFIG.16andFIG.17. In this condition, the position of the rockers is as follows:

RockerPosition (from below)11RANTI-CLOCKWISE12RCLOCKWISE13RCLOCKWISE14RANTI-CLOCKWISE15RANTI-CLOCKWISE16RCLOCKWISE

The motion generator is shown with the chassis3in a yaw nose left condition inFIG.18andFIG.19. In this condition, the position of the rockers is as follows:

RockerPosition (from below)11RCLOCKWISE12RCLOCKWISE13RCLOCKWISE14RCLOCKWISE15RCLOCKWISE16RCLOCKWISE

It will be noted that only a limited number of conditions is described above in relation to the motion generator2. It will be appreciated by the skilled addressee that the motion generator2may be operated into many more conditions including, and not exclusively surge rearward, sway right, heave down, roll left side down, pitch nose up and yaw nose right. Furthermore, it will also be appreciated by the skilled addressee that the motion generator2may be operated into multiple combinations of such conditions. For example, the motion generator may be operated into a combined heave up and yaw nose left condition. The motion generator has the advantages of the invention including high bandwidth, low friction and low inertia which increase the accuracy of the movements of the payload, chassis3.

Control System

FIG.26shows a control system501for use in controlling operation of a motion generator in accordance with the invention. In relation toFIG.26, the motion generator is referred to as502, but the control system501is applicable to the other motion generators, motion systems, and motion simulators described herein. The control system501comprises a motion controller504which executes a computer program, preferably in a deterministic or real time manner, and which takes motion demand inputs505from a demand generator such as a simulation environment503or a set point generator506. The motion controller computes the positions, accelerations and/or forces507required to be produced at each actuator509to in order to generate the demanded motion profile505. The control system501also comprises servo drives508which provide precisely controlled electrical currents510to drive the actuators509.

In operation, the motion controller sends to each servo drive508a demanded position or force507. The actuator509has a motion measurement device511, such as an encoder, which provides motion feedback512to the motion controller, optionally via the servo drive. The motion controller compares the demanded motion profile505to the one measured512and updates the actuator demand507accordingly.

FIG.26also shows the control system with a simulation environment503, such as a driving simulation in which the physics of a simulated vehicle and its environment, such as a racetrack or city roads, are computed. In this embodiment the control system501receives motion demands from the simulation environment503, which represent the motion of a virtual vehicle. The computer program determines the motion of the vehicle in a virtual world514, then applies a motion cueing algorithm513(MCA, also known as washout filters) to transform the simulated vehicle motions into those that can be represented by the motion generator. These calculated motions are then provided to the control system as motion demands505. The MCA513could be part of the simulation environment503or the control system501or separate to both. The simulation environment503may receive inputs signals515from control devices516such as steering, throttle or brake inputs, which an operator, I.e. a human user such as a driver, passenger or pilot uses to control the virtual vehicle in the simulation environment. The operator would likely be a passenger on the motion generator502. These inputs515may be passed back to the simulation environment via the control system or directly. The simulation environment is also likely to produce an output on a visual display517for the driver, passenger, or other user or operator. The simulation environment may also require additional data518from the control system, such as relating to the position of the motion generator, or control device inputs signals.

Combination of Motion Generators

A motion generator in accordance with either aspect of the invention may be used in series with a further motion generator. For example, a motion generator in accordance with the invention may be used as a secondary motion generator, that is to say the motion generator itself becomes the payload of a primary motion generator.FIG.27Ashows a combination600, which is in accordance with the invention, and comprising a first (or “primary”) motion generator602, and a second (or “secondary”) motion generator604(which is a motion generator in accordance with the invention). The combination is installed on a planar surface601(not shown) typically a building floor. The primary motion generator602is a simple X and Y frame arrangement, comprising a lower frame606, including lower frame members607,608, and an upper frame610. The lower frame member608supports a motor612which can be operated, under commands from a control system605(for example as shown inFIG.26) to move the frame610in the X direction. A similar motor614is correspondingly arranged on the frame610to move that frame in the Y direction under commands from the control system605. The secondary motion generator604, which is a motion generator in accordance with the first aspect of the invention mounted on the primary motion generator602, comprises a rocker616(directly mounted on upper frame610of the primary motion generator i.e. it is mounted in a plane above the surface601) which is drivably connected to an actuator (comprising a motor617, and elongate belt618which is attached to the movable end of the rocker, which passes around capstans618CA), and to an elongate rigid strut620. The elongate strut620is connected by a joint at one end to the free end of the associated rocker616and at its other end by a joint to an end effector supporting payload619. When the motor617is operated under commands from the control system, it drives a driven capstans618CA and in turn the belt618to move the associated rocker616. The rocker616pivots about a vertical pivot axis (passing though rocker pivot616P), with the rocker arm describing a horizontal arc (shown as A). The movement of rocker616moves the associated strut620to move the end effector/payload618/619in the X and Y directions, as well permitting yaw, heave and pitch motions. The combination600is advantageous in that the primary motion generator602is relatively inexpensive but provides good excursion ranges in the X and Y directions and the secondary motion generator604provides a higher bandwidth and lower levels of inertia and friction which increase the accuracy of the movements imparted to the payload.

Combination of Motion Generators

FIG.27Bshows another combination300in accordance with the invention, comprising a first (or “primary”) motion generator302, and a second (or “secondary”) motion generator304(which is a motion generator in accordance with the invention). The combination300is installed on a planar surface301such as a floor in a driving simulator building. The primary motion generator302is a simple X and Y frame arrangement, generally as described above in relation to primary motion generator602, comprising a lower frame306, including lower frame members307,308, and an upper frame310. The lower frame member308supports a motor312which can be operated, under commands from a control system305(for example as shown inFIG.26) to move the frame310in the X direction. A similar motor314is correspondingly arranged on the frame310to move that frame in the Y direction under commands from the control system. The secondary motion generator304which is a motion generator in accordance with the second aspect of the invention, comprises six rockers316A-F, each rocker being drivably connected to an actuator (comprising motors317A-F and associated elongate toothed belts318A-F which pass around a correspondingly splined capstan of the associated motor317A-F and a free-moving capstan e.g.318CA or318CB), generally as described in relation to theFIG.1motion generator, and to an elongate rigid strut (struts320A-F). Each of the elongate rigid struts320A-F is connected by a joint at one end to the free end of the associated rocker316A-F and at its other end by a joint to an end effector (platform321supporting payload3322. It will be noted that the rockers316A-F are mounted on the upper frame310of the primary motion generator302in a plane defined by the upper surface of that frame310which is spaced above the surface301. When a motor317A-F is operated under commands from the control system, it drives an associated belt318A-F so that the associated rocker316A-F pivots about a horizontal pivot axis with the rocker arm describing an arc (for example as shown as A for rocker316A). The movement of a rocker316A-F therefore moves the associated strut320A-F to move the end effector/payload318/319in the X and Y directions, as well permitting yaw, heave and pitch motions. The combination300is advantageous in that the primary motion generator302is relatively inexpensive but provides good excursion ranges in the X and Y directions and the secondary motion generator304provides a higher bandwidth and lower levels of inertia and friction which increase the accuracy of the movements of the payload.

Driving Simulator

A driving simulator200in accordance with the invention is shown inFIG.20. The driving simulator200comprises a motion system202including a motion generator204in accordance with the invention, for example as described above in relation toFIGS.1to19or below in relation toFIGS.21-23, or a combination as described in relation toFIG.27B. The motion system202mounted on a surface206in front of a projection system206on which can be displayed images of a driving environment, the projection system constituting an example of an environment simulation means. An audio system (not shown) provides sound to the user replicating the sounds of a driving environment, constituting another example of an environment simulation means. The motion generator204of the driving simulator200is operated under the command of a control system207(for example, as described in relation toFIG.26).

A motion generator in accordance with the invention, as described in several embodiments above, which is suitable for use as used in a driving simulator as described in this embodiment may be advantageous in some or all of several respects compared with known motion generators for such applications. First, it may have low levels of friction within its moving parts owing to a) the use of revolute joints or rotary bearings rather than linear bearings for reacting weight and inertial loads b) dispensing with recirculating ball screw linear actuators. Second, it may have low inertia particularly where rotary motors rather than linear motors are used, particularly linear actuators that move in their entirety with a strut in a mechanism. Where a linear motor is used as an actuator in a motion generator according to this invention, only its forcer need move while its stator or magnetway can remain stationary. Third, it may have high bandwidth typically better than 50 Hz, in more than one degree of freedom. In some embodiments it may have significantly higher bandwidth than 50 Hz, for example 80, 90, 100 or more Hz. It will also be appreciated that the motion generator204used in the driving simulator200may be especially compact in the vertical direction. This better replicates the height of a vehicle being simulated, in comparison with other motion systems requiring ramps/bridges for a user to enter/exit the driving simulator.

Motion System Including a Motion Generator

Another motion system700in accordance with the invention is shown inFIG.21. The motion system700includes a motion generator702in accordance with the invention which supports a payload704above a surface706. The motion generator702comprises four rocker systems710,712,714and716(rocker systems714and716being obscured inFIG.21) which are generally as described above. Linear constraints720and722are arranged at right angles between rocker arrangements710,716and716,714respectively. The motion system700also includes a control system (for example as described in relation toFIG.26).

In use, the rockers710-714are moved by belt drives B, generally as described above so that elongate struts interposed between the rockers and the payload704(again generally as described above) move the payload in four degrees of freedom with high bandwidth. The constraints720,722prevent excessive movement of the payload704in the fore and aft and side to side directions respectively.

It will be appreciated by the skilled addressee that the motion system700may be relatively simple yet offer good performance in terms of bandwidth. The system could have a bandwidth in excess of 50 Hz or even 100 Hz in all degrees of freedom, despite having a lower bandwidth primary motion generator, because the secondary motion generator is highly performing in this regard.

Further Motion Generator

A further motion generator400in accordance with the invention is shown inFIGS.22and23. The motion generator400, which is constructed and arranged generally as described above in relation to the motion generator2shown inFIGS.1to19, except that the six belt-drive linear actuators11LA-16LA are replaced by six linear motors and six linkages which drive corresponding rockers and struts to move a platform402, which constitutes an effector. The six linear motors are operable to move a platform402in six degrees of freedom.FIGS.22and23show one of the six linear motors411in more detail. More specifically,FIG.22shows the coil412and magnetway414of linear motor411. The linear motor411is pivotally connected by pivot416to an elongate lower strut418. A further pivot419connects the strut418to a rocker420. The rocker420is mounted for horizontal pivotal movement on pivot421above and parallel with a surface on which the motion generator400is mounted. An upper strut422is connected by its lower end to the rocker420by a clevis joint424. The upper strut422is, in turn, pivotally connected at its upper end by a further clevis joint425(shown inFIG.23) to the platform402(omitted for clarity inFIG.23). In use, linear movement of the coil (e.g.412) under operation of the linear motor (e.g.411) as controlled by a control system (for example, as described in relation toFIG.26) moves the associated rocker (e.g.420) and connected struts (e.g.418,422) to move the platform (402) in six degrees of freedom.

Alternative Rocker Arrangement

An alternative rocker arrangement is shown schematically inFIGS.24to25. In this embodiment, a motion generator100is mounted on a planar surface generally indicated as102, and supports a chassis103, which constitutes the payload of the motion generator102, and control means (not shown) above a triangular frame105(omitted for clarity). The chassis103, which is constructed of a lightweight rigid material such as aluminium, or carbon fibre, is a replica of a racing car cockpit. The chassis103is supported by pairs of elongate rigid rods or struts,111,112;113,114; and115,116which are connected at their upper ends by upper joints111UJ,112UJ,113UJ,114UJ,115UJ, and116UJ respectively to the chassis103. The elongate rigid rods111-116may be made, for example, of carbon fibre to reduce resonance. The upper joints111UJ-16UJ may be spherical, cardan, or universal joints, and/or may comprise flexures. The lower end of each elongate rod111-116is connected by a lower joint111LJ,112LJ,113LJ,114LJ,115LJ, and116LJ (which may also be spherical, cardan or universal joints and/or may comprise flexures) respectively to rockers111R,112R,113R,114R,115R, and116R, respectively which are arranged for pivotal movement on the inside of the triangular frame105of the motion generator100, being driven by linkages111L,112L;113L,114L; and115L,116L connected to linear actuators111LA,112LA;113LA,114LA; and115LA,116LA.

In contrast with previous embodiments, where the rockers move parallel with the surface on which the motion generator is mounted, as the pivot axis for each rocker is perpendicular to the surface, the rockers111R,112R,113R,114R,115R, and116R are arranged for angled pivoting movement which is non-parallel with the surface (in this case102) on which the motion generator is mounted. In this description, the opposite end of the rocker to the pivot axis is termed the free end. In this embodiment, the rockers are inclined at 45° from the surface (The angle indicated as Θ, between the surface102and the axis A around which the rocker113R pivots is shown inFIG.25). In other embodiments, the pivot rockers may be inclined at 0 to 45° from the surface. Where the surface on which the motion generator is mounted is not planar, the angle of inclination of the rockers is taken from a datum line. Where the motion generator is arranged in a combination as a secondary motion generator, the angle of inclination of the rockers may be taken from a plane defined above the surface, such as by a planar surface of an upper frame of the primary motion generator on which the rockers are mounted. Such a plane may be considered as a “surface”. In some situations, such an inclined rocker arrangement is preferable as it may reduce unwanted resonances. An inclined rocker arrangement may also be more compact. It may also reduce loads reacted by bearings thereby further reducing friction.

Further Alternative Rocker Arrangement

A further alternative rocker arrangement suitable for use in a motion generator in accordance with the invention is illustrated inFIGS.28A and B.FIG.28A shows a rocker400which includes a rocker base402, connected by a flexure404, to rocker arm406. The flexure is formed from a predictable elastic material such as spring steel, tool steel, or a composite such as E-glass or S-glass. The flexure404allows an arcing movement ((indicated as arc C) of the rocker arm406in a plane perpendicular to the flexure404which approximates rotation around an imagined axis in the middle of the flexure404. The rocker arm406is shown in one position on arc C inFIG.28B. The imagined axis may be considered as an equivalent to the pivot axis of the other rockers described above. Such a rocker arrangement incorporating a flexure may be advantageous in that it avoids the use of bearings, it may eliminate backlash, and/or provides increased stiffness.

METHODS OF PRODUCING MOTION SYSTEMS

A motion system in accordance with the invention including a motion generator, such as those described above, and control means may be assembled from custom and standard components by conventional means. In particular, a motion system may be produced by connecting a motion generator in accordance with the invention with a control system.