MOTION GENERATOR

Abstract

According to a first aspect of the invention there is provided a motion generator comprising an effector for applying forces, moments and movements to a payload relative to a surface connected to one or more elongate rigid struts, each strut being connected at one end thereof by a first joint to the effector and being connected at its other end by a second joint to an associated rocker, the rocker having a pivot axis, such that movement of a rocker about the pivot axis leads to movement of the effector, and forces applied to an associated rocker lead to forces being applied to the effector, in which the movement of a rocker and forces applied by the rocker are controlled by an actuator, the actuator being in the form of an elongate belt, cable, rope drive, or linear motor arranged to apply a force to a point on an associated rocker away from the pivot axis of the rocker. According to a second aspect of the invention there is provided a motion generator comprising an effector for applying forces, moments and movements to a payload relative to a surface, the effector being connected to four, or more elongate rigid struts, each strut being connected at one end thereof by a first joint to the effector and being connected at its other end by a second joint to an associated rocker, the rocker having a pivot axis, such that movement of a rocker leads to movement of the effector, and forces applied to an associated rocker lead to forces being applied to the effector, in which the movement of a rocker and forces applied by the rocker are controlled by an actuator, the actuator being arranged to apply a force to a point on an associated rocker away from the pivot axis of the rocker. The invention also relates to motion systems, and driving simulators including such motion generators, and to methods using such motion generators and systems.

Claims

1-31. (canceled)

32. A motion generator comprising an effector for applying forces, moments and movements to a payload relative to a surface connected to one or more elongate rigid struts, each strut being connected at one end thereof by a first joint to the effector and being connected at its other end by a second joint to an associated rocker, the rocker having a pivot axis, such that movement of a rocker about the pivot axis leads to movement of the effector, and forces applied to an associated rocker lead to forces being applied to the effector, in which the movement of a rocker and forces applied by the rocker are controlled by an actuator, the actuator being in the form of an elongate belt, cable, rope drive, or linear motor arranged to apply a force to a point on an associated rocker away from the pivot axis of the rocker.

33. A motion generator comprising an effector for applying forces, moments and movements to a payload relative to a surface, the effector being connected to four, or more elongate rigid struts, each strut being connected at one end thereof by a first joint to the effector and being connected at its other end by a second joint to an associated rocker, the rocker having a pivot axis, such that movement of a rocker leads to movement of the effector, and forces applied to an associated rocker lead to forces being applied to the effector, in which the movement of a rocker and forces applied by the rocker are controlled by an actuator, the actuator being arranged to apply a force to a point on an associated rocker away from the pivot axis of the rocker.

34. The motion generator according to claim 33, in which the actuator is in the form of an elongate belt, cable, or rope drive, or a linear motor.

35. The motion generator according to claim 33, in which there are six struts arranged in three pairs, each of the struts being connected at one of their respective ends with an associated rocker, and the other respective ends of the paired struts connecting to three mounting points or joints of the effector.

36. The motion generator according to claim 33, in which at least one actuator comprises a belt which is attached at at least one end to the associated rocker and applies a force or forces to the rocker.

37. The motion generator according to claim 33, in which the first and second joint together have a total number of degrees of freedom which is at least five.

38. The motion generator according to claim 33, in which one of the first or second joints includes a universal, cardan, spherical joint or flexure, while the other is a spherical joint, or a universal joint or cardan joint or flexure in series with a revolute joint.

39. The motion generator according to claim 33, comprising a plurality of such rockers where the pivot axis of the or each rocker is fixed relative to the surface.

40. The motion generator according to claim 33, comprising a plurality of such rockers where the pivot axes of each rocker are fixed relative to each other.

41. The motion generator according to claim 33, in which at least one rocker's pivot axis is inclined relative to the surface.

42. The motion generator according to claim 41, in which at least one rocker's pivot axis is perpendicular to the surface.

43. The motion generator according to claim 33, in which a rocker forms an obtuse angle with a connected strut.

44. The motion generator according to claim 33, in which there are 5 or 6 elongate struts.

45. The motion generator according to claim 33, wherein the motion generator comprising X elongate struts, where X is less than six, and the motion generator comprising at least one mechanical constraint means which constrains Y degrees of freedom of the effector where Y=6−X.

46. The motion generator according to claim 33, wherein at least one actuator comprises an elongate belt, cable or rope drive, in which that actuator is actuated by a pulley or capstan.

47. The motion generator according to claim 46, wherein the actuator includes a belt, cable, or rope drive, in which both the ends of the belt, cable, or rope drive are attached to an associated rocker, forming a closed loop in the belt, cable, or rope between two attachment points on the associated rocker.

48. The motion generator according to claim 47, in which a passive tensioning device including a pulley is applied to the closed belt, cable, or rope drive to maintain tension in the belt, cable, or rope drive.

49. The motion generator according to claim 33, in which one end of the belt, cable or rope drive is connected to an associated rocker and the other end of the belt, cable or rope drive is attached to a passive force application device which maintains tension in the belt, cable or rope.

50. The motion generator according to claim 33, and wherein the actuator connected to an associated rocker comprises a linkage and a linear motor whereby the linkage connects the rocker to the linear motor.

51. The motion generator according to claim 50, in which the linkage is a fixed length elongate strut having a joint at either end selected from revolute joints, spherical joints, universal or cardan joints, and flexures.

52. The motion generator according to claim 33, in which a passive force application device is connected to a rocker so as to provide assistance such as static preload or damping to the actuator.

53. The motion generator according to claim 33, in which one or more passive force application devices such as a spring, gas strut, bungee is connected to the effector or the payload so as to provide assistance to the actuator.

54. The motion generator according to claim 33, in which at least one rocker and/or actuator is mounted on or to the surface, or is fixed relative to the surface.

55. A combination comprising the motion generator according to claim 33, the motion generator being arranged to operate as a secondary motion generator in series with a primary motion generator.

56. A combination according to claim 55, in which at least one rocker and or actuator of the secondary motion generator is mounted on or to the end effector or payload of the primary motion generator.

57. A combination according to claim 56, in which the primary motion generator includes a frame and at least one of the rockers of the secondary motion generator is pivotally mounted to the frame of the primary motion generator.

57. A combination according to claim 55, in which the secondary motion generator has six struts.

59. A motion system comprising: a control system; and one or more of: one motion generator comprising an effector for applying forces, moments and movements to a payload relative to a surface, the effector being connected to four, or more elongate rigid struts, each strut being connected at one end thereof by a first joint to the effector and being connected at its other end by a second joint to an associated rocker, the rocker having a pivot axis, such that movement of a rocker leads to movement of the effector, and forces applied to an associated rocker lead to forces being applied to the effector, in which the movement of a rocker and forces applied by the rocker are controlled by an actuator, the actuator being arranged to apply a force to a point on an associated rocker away from the pivot axis of the rocker, or at least one combination according to claim 55.

60. A driving simulator comprising: at least one environment simulation means selected from visual projection or display means, and audio means; and one or more of: a combination according to claim 55, or a motion system comprising an effector for applying forces, moments and movements to a payload relative to a surface, the effector being connected to four, or more elongate rigid struts, each strut being connected at one end thereof by a first joint to the effector and being connected at its other end by a second joint to an associated rocker, the rocker having a pivot axis, such that movement of a rocker leads to movement of the effector, and forces applied to an associated rocker lead to forces being applied to the effector, in which the movement of a rocker and forces applied by the rocker are controlled by an actuator, the actuator being arranged to apply a force to a point on an associated rocker away from the pivot axis of the rocker.

61. A method of producing the motion generator according to claim 32, the method comprising providing an effector suitable for applying forces, moments and movements to a payload relative to a surface, connecting to four or more elongate rigid struts, connecting each strut at one end thereof by a first joint to the effector and at its other end by a second joint to a rocker, the rocker having a fixed pivot axis, such that movement of a rocker leads to movement of the effector, and forces applied to a rocker lead to forces being applied to the effector, and in which the movement of a rocker and forces applied by the rocker are controlled by an actuator, the actuator being arranged to apply a force to a point on a rocker away from the pivot axis of the rocker.

62. A method of producing a motion system according to claim 59, comprising connecting a control system to a motion generator comprising an effector for applying forces, moments and movements to a payload relative to a surface, the effector being connected to four, or more elongate rigid struts, each strut being connected at one end thereof by a first joint to the effector and being connected at its other end by a second joint to an associated rocker, the rocker having a pivot axis, such that movement of a rocker leads to movement of the effector, and forces applied to an associated rocker lead to forces being applied to the effector, in which the movement of a rocker and forces applied by the rocker are controlled by an actuator, the actuator being arranged to apply a force to a point on an associated rocker away from the pivot axis of the rocker.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Motion generators, motion systems, and driving simulators and their operation and production in accordance with the invention will now be described, by way of example only, with reference to the accompanying drawings, FIGS. 1 to 28, in which:

[0035] FIG. 1 is a schematic perspective view of a motion system in accordance with the invention, from above and one side;

[0036] FIG. 2 is a schematic perspective view of the motion system of FIG. 1 with the frame removed for clarity;

[0037] FIG. 3 is a plan view of the motion system as shown in FIG. 2;

[0038] FIG. 4 is a schematic detailed plan view of a rocker of the motion system of FIG. 1;

[0039] FIG. 5 is a schematic perspective view of the rocker shown in FIG. 4;

[0040] FIG. 6 is a detailed plan view of a different rocker for use in a motion generator in accordance with the invention;

[0041] FIG. 7 is a detailed view of passive tension devices of a motion generator in accordance with the invention;

[0042] FIG. 8 is a perspective view of the motion system as shown in FIG. 2 in a surge forward condition;

[0043] FIG. 9 is a plan view from below of the motion system in the surge forward condition of FIG. 8;

[0044] FIG. 10 is a perspective view of the motion system as shown in FIG. 2 in a sway left condition;

[0045] FIG. 11 is a plan view from below of the motion system in the sway left condition of FIG. 10;

[0046] FIG. 12 is a perspective view of the motion system as shown in FIG. 2 in a heave up condition;

[0047] FIG. 13 is a plan view from below of the motion system in the heave up condition of FIG. 12;

[0048] FIG. 14 is a perspective view of the motion system as shown in FIG. 2 in a roll right side down condition;

[0049] FIG. 15 is a plan view from below of the motion system as shown in FIG. 14 in the roll right side down condition;

[0050] FIG. 16 is a perspective view of the motion system as shown in FIG. 2 in a pitch nose down condition;

[0051] FIG. 17 is a plan view from below of the motion system in the pitch nose down condition of FIG. 16;

[0052] FIG. 18 is a perspective view of the motion system as shown in FIG. 1 in a yaw nose left condition;

[0053] FIG. 19 is a plan view from below of the motion system in the yaw nose left condition shown in FIG. 18;

[0054] FIG. 20 is a perspective view of a driving simulator in accordance with the invention;

[0055] FIG. 21 is a schematic perspective view of another motion system in accordance with the invention;

[0056] FIG. 22 is a perspective detail view of another motion generator in accordance with the invention;

[0057] FIG. 23 is a further detail view of the motion generator of FIG. 22;

[0058] FIG. 24 is a partial view of another motion generator showing an alternative rocker arrangement;

[0059] FIG. 25 is a further partial rear view of the motion generator of FIG. 24 showing the inclination of a rocker arrangement;

[0060] FIG. 26 is a schematic view of a control system for use with motion generators of the invention;

[0061] FIG. 27A is a schematic view of a combination including a motion generator in accordance with the invention, and another motion generator; and

[0062] FIG. 27B is a schematic view of another combination including a motion generator in accordance with the invention, and another motion generator; and

[0063] FIG. 28 is a schematic view of an alternative rocker arrangement.

[0064] 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.

DESCRIPTION

[0065] Motion System Including a Motion Generator

[0066] A motion system 1 including a motion generator 2 in accordance with a first aspect of the invention is shown in FIGS. 1 to 19. The motion system 1 comprises a motion generator 2 mounted on a surface 4, and supports a vehicle chassis 3, which, in this embodiment, constitutes the payload of the motion generator 2, and control means (for example as described in relation to FIG. 26) above a frame 5. The frame 5 has 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 chassis 3 is a replica of a racing car cockpit. The chassis 3 is supported by pairs of elongate rigid rods or struts, 11, 12; 13, 14; and 15, 16 which at their upper ends are connected by upper joints 11 UJ, 12 UJ, 13 UJ, 14 UJ, 15 UJ, and 16 UJ respectively to the chassis 3. The elongate rigid rods 11-16 may be made, for example, of carbon fibre to reduce resonance. The upper joints 11UJ-16UJ may be spherical, cardan, or universal joints, and/or may comprise flexures. The lower end of each elongate rod 11-16 is connected by a lower joint 11LJ, 12LJ, 13LJ, 14LJ, 15LJ, and 16LJ respectively to an associated rocker 11R, 12R, 13R, 14R, 15R, and 16R, respectively which are arranged for pivotal movement on the inside of the triangular frame 5 of the motion generator 2. The lower joints 11 LJ-16 LJ may also be spherical, cardan or universal joints, and/or may comprise flexures. Linear actuators 11LA-16 LA 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 rockers 11 R-16R and the linear actuators 11 LA-16 LA is shown in more detail in FIGS. 4-7.

[0067] It is contemplated that a motion generator in accordance with the invention may not include a frame 5. In such an arrangement, at least some of, or all, the rockers and/or actuators could be mounted directly on the surface 4 rather 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.

[0068] FIGS. 4 and 5 show rocker 16R and connected elements in more detail. The continuous toothed belt B connects with the rocker 16R 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. In FIGS. 4 and 5, the elements E are circular. In FIG. 6, the corresponding elements E are curved. It should be noted that the belt B shown in FIG. 6 is 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 to FIG. 26).

[0069] It will also be noted that the passive tension elements P in the embodiment of FIGS. 4 and 5 are bungees or springs. In the embodiment shown in FIGS. 6 and 7, 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 rocker 11R-16R against the belt B connected to that rocker. By movement of one or more of the rockers 11R-16R driven by the associated belts B and capstans C under the control of the control system, the rods or struts 11-16 move the chassis 4, at high bandwidth in any of six degrees of freedom into a wide variety of conditions, some of which are described below.

[0070] The motion generator 2, 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.

[0071] In the following description, the position of the rockers 11 R-16R in use is described in more detail. For simplicity, only the position of the rockers 11 R-16 R 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 struts 11-16, 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 to FIGS. 1 to 3 and 7-17.

[0072] The motion generator 2 is shown with the chassis 3 in a neutral condition in FIGS. 1 to 3. In this condition, the state of the rockers is as follows:

TABLE-US-00001 Rocker Position from below 11R Neutral 12R Neutral 13R Neutral 14R Neutral 15R Neutral 16R Neutral

[0073] The motion generator is shown with the chassis 3 in a surge forward condition in FIGS. 8 and 9. In this condition, the states of the rockers is as follows:

TABLE-US-00002 Rocker Position from below 11R Anti-clockwise 12R Anti-clockwise 13R NEUTRAL 14R Neutral 15R CLOCKWISE 16R CLOCKWISE

[0074] The motion generator is shown with the chassis 3 in a sway left condition in FIG. 10 and FIG. 11. In this condition, the position of the rockers is as follows:

TABLE-US-00003 Rockers Position from below 11R CLOCKWISE 12R CLOCKWISE 13R ANTI-CLOCKWISE 14R ANTI-CLOCKWISE 15R CLOCKWISE 16R CLOCKWISE

[0075] The motion generator is shown with the chassis 3 in a heave up condition in FIG. 12 and FIG. 13. In this condition, the position of the rockers is as follows:

TABLE-US-00004 Rocker Position (from below) 11R CLOCKWISE 12R ANTI-CLOCKWISE 13R CLOCKWISE 14R ANTI-CLOCKWISE 15R CLOCKWISE 16R ANTI-CLOCKWISE

[0076] The motion generator is shown with the chassis 3 in a roll right side down condition in FIG. 14 and FIG. 15. In this condition, the position of the rockers is as follows:

TABLE-US-00005 Rocker Position (from below) 11R CLOCKWISE 12R ANTI-CLOCKWISE 13R Neutral 14R Neutral 15R ANTI-CLOCKWISE 16R CLOCKWISE

[0077] The motion generator is shown with the chassis 3 in a pitch nose down condition in FIG. 16 and FIG. 17. In this condition, the position of the rockers is as follows:

TABLE-US-00006 Rocker Position (from below) 11R ANTI-CLOCKWISE 12R CLOCKWISE 13R CLOCKWISE 14R ANTI-CLOCKWISE 15R ANTI-CLOCKWISE 16R CLOCKWISE

[0078] The motion generator is shown with the chassis 3 in a yaw nose left condition in FIG. 18 and FIG. 19. In this condition, the position of the rockers is as follows:

TABLE-US-00007 Rocker Position (from below) 11R CLOCKWISE 12R CLOCKWISE 13R CLOCKWISE 14R CLOCKWISE 15R CLOCKWISE 16R CLOCKWISE

[0079] It will be noted that only a limited number of conditions is described above in relation to the motion generator 2. It will be appreciated by the skilled addressee that the motion generator 2 may 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 generator 2 may 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, chassis 3.

[0080] Control System

[0081] FIG. 26 shows a control system 501 for use in controlling operation of a motion generator in accordance with the invention. In relation to FIG. 26, the motion generator is referred to as 502, but the control system 501 is applicable to the other motion generators, motion systems, and motion simulators described herein. The control system 501 comprises a motion controller 504 which executes a computer program, preferably in a deterministic or real time manner, and which takes motion demand inputs 505 from a demand generator such as a simulation environment 503 or a set point generator 506. The motion controller computes the positions, accelerations and/or forces 507 required to be produced at each actuator 509 to in order to generate the demanded motion profile 505. The control system 501 also comprises servo drives 508 which provide precisely controlled electrical currents 510 to drive the actuators 509.

[0082] In operation, the motion controller sends to each servo drive 508 a demanded position or force 507. The actuator 509 has a motion measurement device 511, such as an encoder, which provides motion feedback 512 to the motion controller, optionally via the servo drive. The motion controller compares the demanded motion profile 505 to the one measured 512 and updates the actuator demand 507 accordingly.

[0083] FIG. 26 also shows the control system with a simulation environment 503, 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 system 501 receives motion demands from the simulation environment 503, which represent the motion of a virtual vehicle. The computer program determines the motion of the vehicle in a virtual world 514, then applies a motion cueing algorithm 513 (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 demands 505. The MCA 513 could be part of the simulation environment 503 or the control system 501 or separate to both. The simulation environment 503 may receive inputs signals 515 from control devices 516 such 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 generator 502. These inputs 515 may 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 display 517 for the driver, passenger, or other user or operator. The simulation environment may also require additional data 518 from the control system, such as relating to the position of the motion generator, or control device inputs signals.

[0084] Combination of Motion Generators

[0085] 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. 27A shows a combination 600, which is in accordance with the invention, and comprising a first (or “primary”) motion generator 602, and a second (or “secondary”) motion generator 604 (which is a motion generator in accordance with the invention). The combination is installed on a planar surface 601 (not shown) typically a building floor. The primary motion generator 602 is a simple X and Y frame arrangement, comprising a lower frame 606, including lower frame members 607, 608, and an upper frame 610. The lower frame member 608 supports a motor 612 which can be operated, under commands from a control system 605 (for example as shown in FIG. 26) to move the frame 610 in the X direction. A similar motor 614 is correspondingly arranged on the frame 610 to move that frame in the Y direction under commands from the control system 605. The secondary motion generator 604, which is a motion generator in accordance with the first aspect of the invention mounted on the primary motion generator 602, comprises a rocker 616 (directly mounted on upper frame 610 of the primary motion generator i.e. it is mounted in a plane above the surface 601) which is drivably connected to an actuator (comprising a motor 617, and elongate belt 618 which is attached to the movable end of the rocker, which passes around capstans 618CA), and to an elongate rigid strut 620. The elongate strut 620 is connected by a joint at one end to the free end of the associated rocker 616 and at its other end by a joint to an end effector supporting payload 619. When the motor 617 is operated under commands from the control system, it drives a driven capstans 618CA and in turn the belt 618 to move the associated rocker 616. The rocker 616 pivots about a vertical pivot axis (passing though rocker pivot 616P), with the rocker arm describing a horizontal arc (shown as A). The movement of rocker 616 moves the associated strut 620 to move the end effector/payload 618/619 in the X and Y directions, as well permitting yaw, heave and pitch motions. The combination 600 is advantageous in that the primary motion generator 602 is relatively inexpensive but provides good excursion ranges in the X and Y directions and the secondary motion generator 604 provides a higher bandwidth and lower levels of inertia and friction which increase the accuracy of the movements imparted to the payload.

[0086] Combination of Motion Generators

[0087] FIG. 27B shows another combination 300 in accordance with the invention, comprising a first (or “primary”) motion generator 302, and a second (or “secondary”) motion generator 304 (which is a motion generator in accordance with the invention). The combination 300 is installed on a planar surface 301 such as a floor in a driving simulator building. The primary motion generator 302 is a simple X and Y frame arrangement, generally as described above in relation to primary motion generator 602, comprising a lower frame 306, including lower frame members 307, 308, and an upper frame 310. The lower frame member 308 supports a motor 312 which can be operated, under commands from a control system 305 (for example as shown in FIG. 26) to move the frame 310 in the X direction. A similar motor 314 is correspondingly arranged on the frame 310 to move that frame in the Y direction under commands from the control system. The secondary motion generator 304 which is a motion generator in accordance with the second aspect of the invention, comprises six rockers 316A-F, each rocker being drivably connected to an actuator (comprising motors 317A-F and associated elongate toothed belts 318A-F which pass around a correspondingly splined capstan of the associated motor 317A-F and a free-moving capstan e.g. 318CA or 318CB), generally as described in relation to the FIG. 1 motion generator, and to an elongate rigid strut (struts 320A-F). Each of the elongate rigid struts 320A-F is connected by a joint at one end to the free end of the associated rocker 316A-F and at its other end by a joint to an end effector (platform 321 supporting payload 3322. It will be noted that the rockers 316A-F are mounted on the upper frame 310 of the primary motion generator 302 in a plane defined by the upper surface of that frame 310 which is spaced above the surface 301. When a motor 317A-F is operated under commands from the control system, it drives an associated belt 318A-F so that the associated rocker 316A-F pivots about a horizontal pivot axis with the rocker arm describing an arc (for example as shown as A for rocker 316A). The movement of a rocker 316A-F therefore moves the associated strut 320A-F to move the end effector/payload 318/319 in the X and Y directions, as well permitting yaw, heave and pitch motions. The combination 300 is advantageous in that the primary motion generator 302 is relatively inexpensive but provides good excursion ranges in the X and Y directions and the secondary motion generator 304 provides a higher bandwidth and lower levels of inertia and friction which increase the accuracy of the movements of the payload.

[0088] Driving Simulator

[0089] A driving simulator 200 in accordance with the invention is shown in FIG. 20. The driving simulator 200 comprises a motion system 202 including a motion generator 204 in accordance with the invention, for example as described above in relation to FIGS. 1 to 19 or below in relation to FIGS. 21-23, or a combination as described in relation to FIG. 27B. The motion system 202 mounted on a surface 206 in front of a projection system 206 on 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 generator 204 of the driving simulator 200 is operated under the command of a control system 207 (for example, as described in relation to FIG. 26).

[0090] 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 generator 204 used in the driving simulator 200 may 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.

[0091] Motion System Including a Motion Generator

[0092] Another motion system 700 in accordance with the invention is shown in FIG. 21. The motion system 700 includes a motion generator 702 in accordance with the invention which supports a payload 704 above a surface 706. The motion generator 702 comprises four rocker systems 710, 712, 714 and 716 (rocker systems 714 and 716 being obscured in FIG. 21) which are generally as described above. Linear constraints 720 and 722 are arranged at right angles between rocker arrangements 710, 716 and 716, 714 respectively. The motion system 700 also includes a control system (for example as described in relation to FIG. 26).

[0093] In use, the rockers 710-714 are moved by belt drives B, generally as described above so that elongate struts interposed between the rockers and the payload 704 (again generally as described above) move the payload in four degrees of freedom with high bandwidth. The constraints 720, 722 prevent excessive movement of the payload 704 in the fore and aft and side to side directions respectively.

[0094] It will be appreciated by the skilled addressee that the motion system 700 may 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.

[0095] Further Motion Generator

[0096] A further motion generator 400 in accordance with the invention is shown in FIGS. 22 and 23. The motion generator 400, which is constructed and arranged generally as described above in relation to the motion generator 2 shown in FIGS. 1 to 19, except that the six belt-drive linear actuators 11LA-16 LA are replaced by six linear motors and six linkages which drive corresponding rockers and struts to move a platform 402, which constitutes an effector. The six linear motors are operable to move a platform 402 in six degrees of freedom. FIGS. 22 and 23 show one of the six linear motors 411 in more detail. More specifically, FIG. 22 shows the coil 412 and magnetway 414 of linear motor 411. The linear motor 411 is pivotally connected by pivot 416 to an elongate lower strut 418. A further pivot 419 connects the strut 418 to a rocker 420. The rocker 420 is mounted for horizontal pivotal movement on pivot 421 above and parallel with a surface on which the motion generator 400 is mounted. An upper strut 422 is connected by its lower end to the rocker 420 by a clevis joint 424. The upper strut 422 is, in turn, pivotally connected at its upper end by a further clevis joint 425 (shown in FIG. 23) to the platform 402 (omitted for clarity in FIG. 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 to FIG. 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.

[0097] Alternative Rocker Arrangement

[0098] An alternative rocker arrangement is shown schematically in FIGS. 24 to 25. In this embodiment, a motion generator 100 is mounted on a planar surface generally indicated as 102, and supports a chassis 103, which constitutes the payload of the motion generator 102, and control means (not shown) above a triangular frame 105 (omitted for clarity). The chassis 103, which is constructed of a lightweight rigid material such as aluminium, or carbon fibre, is a replica of a racing car cockpit. The chassis 103 is supported by pairs of elongate rigid rods or struts, 111, 112; 113, 114; and 115, 116 which are connected at their upper ends by upper joints 111 UJ, 112 UJ, 113 UJ, 114 UJ, 115 UJ, and 116 UJ respectively to the chassis 103. The elongate rigid rods 111-116 may be made, for example, of carbon fibre to reduce resonance. The upper joints 111UJ-16UJ may be spherical, cardan, or universal joints, and/or may comprise flexures. The lower end of each elongate rod 111-116 is connected by a lower joint 111LJ, 112LJ, 113LJ, 114LJ, 115LJ, and 116LJ (which may also be spherical, cardan or universal joints and/or may comprise flexures) respectively to rockers 111R, 112R, 113R, 114R, 115R, and 116R, respectively which are arranged for pivotal movement on the inside of the triangular frame 105 of the motion generator 100, being driven by linkages 111L, 112L; 113L, 114L; and 115L, 116L connected to linear actuators 111LA, 112 LA; 113 LA, 114 LA; and 115LA, 116 LA.

[0099] 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 rockers 111R, 112R, 113R, 114R, 115R, and 116R are arranged for angled pivoting movement which is non-parallel with the surface (in this case 102) 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 surface 102 and the axis A around which the rocker 113R pivots is shown in FIG. 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.

[0100] Further Alternative Rocker Arrangement

[0101] A further alternative rocker arrangement suitable for use in a motion generator in accordance with the invention is illustrated in FIGS. 28 A and B. FIG. 28 A shows a rocker 400 which includes a rocker base 402, connected by a flexure 404, to rocker arm 406. 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 flexure 404 allows an arcing movement ((indicated as arc C) of the rocker arm 406 in a plane perpendicular to the flexure 404 which approximates rotation around an imagined axis in the middle of the flexure 404. The rocker arm 406 is shown in one position on arc C in FIG. 28 B. 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.

[0102] Methods of Producing Motion Systems

[0103] 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.