GB2383783A

GB2383783A - Motion simulator

Info

Publication number: GB2383783A
Application number: GB0200303A
Authority: GB
Inventors: Paul Michael Brown; Alexander Guy Wallis; David William Smith; Richard Martin Greenhill; Hugo Elias; Matthew Godden; Richard Walker
Original assignee: GENTILE WILLIAMS MARC DE
Current assignee: GENTILE WILLIAMS MARC DE
Priority date: 2002-01-08
Filing date: 2002-01-08
Publication date: 2003-07-09
Also published as: GB0200303D0

Abstract

A motion simulator, replicating the movements experienced in a motor vehicle or aeroplane, for example, comprises four pivotally-mounted jack arrangements, two under each side of a seat portion 27, differential operation of which in pairs on each side of the seat by actuators (19c, 19d, Fig. 6) causes the seat to pivot about a fore-and aft axis below the level of the seat portion 27. Operating the jack arrangements together causes the seat to rise or "heave". Two further actuators (19a, 19b, Fig. 6) to cause the seat to move forwards or backwards, one actuator for each direction, whilst pivoting about a transverse axis above the level of the portion 27 of the seat. The actuators may be "air muscles", comprising air-pressurisable rubber tubes which shorten when expanded, these acting through pulleys. The actuators are controlled electronically through a computer and in response to controls, e.g. 107, 111, controlled by the operator of the simulator.

Description

MOTION SIMULATOR APPARATUS This invention relates to motion simulator apparatus, intended primarily for use as or as part of a system in the simulation of the sensation, the'feel', that would be experienced by an occupant of a seat, were that seat occupant to be subject to high accelerations such as are to be expected when travelling in a road vehicle at high speed over tortuous courses, or to aerodynamic manoeuvres performed at high speed by an aircraft, for examples.

The contribution to the art on which the present invention in its broader aspect is concerned is predicated on the appreciation, arrived at in the course of investigation of possible modes of operation of a seat for a computer game, that in the simulation of the acceleration sensations, the'feel', experienced by a user of a motion simulation platform, a chair, say, a greater realism is to be achieved if the platform be constrained for pitch angular displacement about a first axis extending transversely of the platform at a position which, at all times, is above the head of a platform user, and a second axis extending in the direction fore and aft of the platform at a position below the platform. The prior art, to the best evidence available, appears not to have recognized this.

The hereinafter described embodiment of the invention not only presents a motion simulator apparatus the operational characteristics of which are consonant with the insight gained as to the aforestated desirable characteristics, but also an account of a novel and

ingenious manner of implementing the principle in an economic and efficient manner.

Throughout the description hereinafter given of a preferred embodiment of apparatus and system in accordance with the invention, reference is had to the use of air muscles as actuators for the several parts of the apparatus.

An air muscle sometimes referred to, variously, as fluidic muscle, rubbertuator, or McKibben muscle, comprises: an expansible tubular chamber, generally of an elastomeric material, most commonly rubber, having an air inlet port and an air exhaust port, a common port being, generally, employed for both of these functions; a braided sheath which embraces said tubular chamber throughout its length; and first and second closure arrangements, at the ends, respectively, of the tubular chamber.

The Specification of UK Patent GB No 2255961, dated 13 March 1992, contains a disclosure of a mechanical actuator having an air muscle as above stated, the air muscle serving as actuator traction element.

The air inlet and exhaust porting means of the air muscle may be constituted as a single combined port commonly integral with one or the other of the closure arrangements, but it may be separate from such closure arrangement, being, advantageously, a tapping at the midlength position of the tubular chamber.

Introduction of air, or other suitable fluid, under pressure, to the chamber causes it to expand rapidly, this, in turn, producing radial expansion, also, of the

braided sheath. It is characteristic of the braided sheath, that radial expansion of its expansible tubular chamber is accompanied by a contraction in sheath length.

If the ends of the sheath are respectively coupled, the one to a, possibly movable, frame part, a force-reaction part of the actuation system, the other to a system part movable with respect to said reaction part, contraction of the braided sheath gives rise to a tensile force which acts on the movable system part, moving it against reaction at the datum force-reaction part through a displacement determined by the extent of contraction in the sheath length.

Air muscles need to be pulled out when'empty' (relaxed) in order to be able, when called upon, to deliver their full stroke when inflated.

Commonly this extension of the muscle is achieved by a conventional mechanical spring arrangement or other similar elastic means which carries out the return movement of a part to be moved.

Sometimes, as with certain of the air muscles employed in the hereinafter described embodiment of the apparatus, recovery of the air muscle to the extended state is accomplished using a second air muscle coupled to the first such as to act antagonistically, contraction in length of the sheath of the first muscle acting to extend the second muscle to its uninflated length.

Sometimes, also, as with certain other air muscles employed in the hereinafter described embodiment, return of the muscles is effected under the action of gravity.

In each case, a return movement is effected of a part that has been moved by the sheath of an air muscle under previous inflation of its tubular chamber.

According to the invention, a motion simulator apparatus and a system incorporating said apparatus are as specified in the claiming clauses, or any of them, accompanying this Application and, accordingly, the content of said claiming clauses and the interrelationships therebetween are to be regarded, notionally, as being here set forth, mutatis mutandis, also.

A motion simulator apparatus and a motion simulator system incorporating such apparatus, all in accordance with the invention, are hereinafter described with reference to the accompanying drawings in which: Fig. 1 shows, in side elevation, the motion simulator of the system; Fig. 2 shows the seat of Fig. 1 in front elevation; Fig. 3 is a scrap diagram showing part of the mechanism incorporated in the seat base of the seat of Figs. 1 and 2, together with a representation, in ghost, of the seat base of the motion simulator; Fig. 4a is a view corresponding to Fig. 2 but with the seat occupant-part of the seat tilted to one of its extreme roll positions; Fig. 4b is a scrap view of a portion of the seat occupant-part shown in Fig. 4a; Fig. 5a is a view again corresponding to Fig. 2 but with the seat occupant part tilted to the extreme roll position opposite to that of Fig. 4a;

Fig. 5b is a scrap view of a portion of the seat occupant-part shown in Fig. 5a ; Fig. 6 is an exploded pictorial diagram showing the platform portion of the seat occupant-part of the motion simulator together with essentially all of the elements of the mechanism for imparting motion to the seat occupant-part with respect to the seat base; Figs. 7a and 7b are views taken at sections A---A and B--B, respectively, and show the modus operand of the seat in fore and aft movements of the seat occupant-part with respect to the seat base; Figs. 8a to 8c are diagrams illustrating changes in the geometry of the seat in the course of fore and aft movements of the seat occupant part executed as shown in Figs. 7a and 7b ; Figs. 9a and 9b are diagrams showing the modus operand of the seat in roll movements of the seat occupant-part with respect to the seat base; Figs. l0 and 11 are scrap diagrams illustrating features of the mechanism; and, Fig. 12 is a block schematic diagram of a system incorporating the motion simulator apparatus of Figs. l to 11.

The motion simulator apparatus 11 of the system comprises: a seat base 13; a seat occupant-part 15; between said seat-occupant part 15 and said seat base, and forming part of said seat base, interface adaptor means 13', and coupling said adaptor means 13'and said seat occupant-part 15, a seat occupant-part motion director

mechanism 17; a multiplicity of actuators, as 19a to 19d (Fig. 6); and a multiplicity of sensors, certain ones, as 21a, of which, being sensors respectively associated with said actuators 19a to 19d, serve to sense extension of the associated said actuator, others, as 21b, of which are located such as to sense angular displacements occurring in the motion director mechanism 17 consequent upon rectilinear displacements occurring, in use of the system, in said actuators.

The seat base 13 comprises, in the example, a pillar 23 upstanding from the hub of a spider-form, groundcontacting part 25. The seat occupant-part 15 has a platform portion 27, and a seat back portion 29. The platform portion 27 comprises a rigid frame, suitably a substantially rigid sheet member 31 of steel, or of a structural plastic material, overlaid with cushioning material 33.

The adaptor means 13'of the base 13 comprises a subframe having first and second beams 35a, 35b, respectively, said beams being held parallel to one another by first and second cross-struts 37a, 37b, respectively, secured, as by welding, to the undersides of the beams 35a, 35b.

The beams 35a, 35b, are each pierced through from side to side with two aligned holes, correspondingly located in the beams, and first and second spindle members 39a, 39b, extend, respectively, through said aligned holes, to form spar portions, as 41, projecting laterally from the beams 35a, 35b, adjacent to the ends thereof.

The adaptor means 13'also comprises a plate 43 (Fig. 6) which is screw-connected to the cross-struts 37a, 37b, of the adaptor sub-frame and which has a central opening 43' adapted to receive the upper end of the pillar 23 of the seat base 13. Housings 44a, 44b, respectively, the one 44a housing electronic components, the other 44b housing pneumatic valves (not shown) operable, as hereinafter indicated, in response to signals from electronic components within the housing 44a.

The mechanism 17 comprises first and second seat occupant-part motion-director means 45a, 45b, respectively, best recognized in the representation of Fig. 6.

The first motion-director means 45a comprises first and second laterally spaced fore and aft extensive track members 47,49, respectively, of a, generally, bow shape, concave upwards and residing in parallel planes laterally of the platform portion 27.

The track members 47,49, each comprise two contiguous track portions, 47a, 47b ; 49a, 49b, as the case may be, supported each at one end by a bracket, 51a, 51b, as the case may be, dependant from straight bars 53,55, respectively, at their mid-length positions, and at the other end at a cranked end-portions, 53', 55', respectively, the two portions of each track member 47, 49, converging to said central brackets 51a, 51b, being

inclined downwardly from said cranked end portions 53', 55', to meet at said central brackets 51a or 51b, as the case may be. The straight bars 53, 55, each have two

lugs 57a, 57b; 59a, 59b, as the case may be, the rigid sheet member 31 of the platform 27 being secured to the bars 53,55, by nut and bolt connectors (not shown) the bolts of which extend through holes, as 59a', 59b', through the lugs 57a, 57b; 59a, 59b, and through correspondingly distributed holes, as 31a, through said rigid sheet member 31. With the bars 51,53, so secured, the longitudinal axes of the track members 45,47 are contained in transversely spaced parallel planes, to extend in the fore and aft direction of the seat platform portion 27.

The second motion director 45b means comprises first and second jack arrangements 61,63, respectively. Each said jack arrangement comprises first and second jack devices 61a, 61b; 63a, 63b, respectively. Each said jack device comprises a pair of identically contoured plates, as 65a, 65b, respectively, held spaced apart, parallel to one another, by means of cross-pin members, as 67.

Corresponding ends of the plate-pairs 65a, 65b, are bridged by end-walls, as 69, each said end-wall 69 having an aperture within which is housed a bearing 71, see, especially, Fig. 10, being a composite bearing having a ball joint portion 73, and a cylindrical bearing portion 75. The segments 47a, 47b; 49a, 49b, of the track members 47,49, extend through respective ones of the cylindrical bearing portions 75 of the composite bearings 71.

The plate-pairs 65a, 65b, have aligned apertures, as 77a, 77b, to receive respective ones of projecting spar

portions 41 of spindles 39a, 39b. The plate-pairs 65a, 65b, are free for pivotal movement about and are axially slideable along the spindle spar portions 41 on which they are respectively mounted.

Corresponding plates of each of the plate-pairs 65a, 65b, of the jack devices are strapped together by first and second tie members, as 79,81, respectively, said tie members being pivotally connected at their ends for angular movement about pins the axes of which are transverse to the plate-pairs 65a, 65b. The axial position of the spindle spar portions 41 and the positions of the composite bearings 71 are such that angular displacement of the plate-pairs 65a, 65b, about their respective spar portions 41 gives rise to an amplified vertical displacement component at the radial distance between the axes of the spar portions 41 and the positions of the bearings 71, and, hence, of the associated track member 47,49, as the case may be, extending therethrough.

The tie members 79,81, constrain the jack devices 61,63, such as to ensure angular movement of equal magnitude and opposite sense of the so-coupled jack devices about their respective spar portions 41.

The actuators 19, of which there are four, are preferably, and as shown, air muscles. Two 19a, 19b, of the air muscles are associated with the first motion director means 45a, the other two 19c, 19d, with the second motion director means 45b.

One end 83 of each air muscle, as 19b, is closed by a cylindrical bung member, as 19b', the muscle sheaths 85

being clamped at their ends by circlips, as 87, each said circlip ensuring tight end-closure of the muscle bladder 89. Air is admitted to and exhausted from the air muscle bladders 89 by way of inlets, as 91, which communicate, respectively, with the bladders, the outer ones directly with the bladders at the mid-length positions thereof, the inner ones by way of the cylindrical bungs, 19b'.

The bungs 19a', 19b', of the inner air muscles 19a, 19b, have, each, a diametral passage through which extend the spindles 39a, 39b, respectively, the inner air muscles 19a, 19b, being thereby anchored to the adaptor means 13' of the seat base 13.

The air inner muscles 19a, 19b, are connected at their other ends to first and second lugs 93a, 93b, (Figs. 7a and 7b) which project from the platform portion 27, by way of first and second pulley systems 95a, 95b, respectively, see, especially, Fig. 11.

Each of said pulley systems 95a, 95b, comprises first, second, and third pulleys, as 97a, 97b, and 97c, respectively. The pulley 97a is rotatable on an axle, as 99, projecting radially outwardly from a bung as 19b', being a bung remote from a spindle, such as 39a, to which the muscle, as 19b, is anchored as aforesaid. The pulleys 97b, 97c, associated with the two inner air muscles 19a, 19b, are independently rotatable, those associated with the air muscle 19a on the spindle 39a, those associated with the air muscle 19b on the spindle 39b.

The other element of each pulley system comprises a

strong rope 101 which extends around the several said pulleys, being connected at one end to the axle 99 and, at the other to one or the other of the lugs 93a, 93b projecting from the seat platform portion 27. The rope 101 is, suitably, of a kind commonly employed as sheets in present day sailing vessels, and, typically, comprises a core part composed of the synthetic plastic material Spectra (Registered Trade Mark), and a woven Nylon sheath cladding, the latter to enhance resistance of the rope to abrasion. The essential property, apart from tensile strength, of the rope, however, is that it shall be substantially inextensible.

The outer air muscles 19c, 19d, are coupled, the one 19c between said jack devices 61a, 61b, the other 19d between said jack devices 63a, 63b. More particularly, the bungs 19c', 19d', at the ends of the outer air muscles 19c, 19d, have axial connector pieces, as 103, linking the muscle ends to the jack devices 61a, 61b,; 63a, 63b, as the case may be.

Expansion of the bladder 89 of one or the other of the outer air muscles 19c, 19d, under air, under pressure, admitted, from an air compressor (not shown), produces a contraction in the length in the muscle sheath 85, and the consequent development, by the sheath, of a tractive force which, acting on the tie-coupled jack devices, as 61a and 61b, gives rise to a displacement of the so-coupled jack devices, in opposite senses and through equal angles, about their respective spindles 41. The track members 47, 49, extending, as they do, through respective ones of the

two bearings 71, one in each jack device, angular displacement of the tie-coupled jack devices 61a, 61b, or the tie-coupled jack devices 63a, 63b, raises the relevant track member 47 or 49, as the case may be, the ball joint portions 73'of the composite joints 71 adopting an appropriate angular position, and the cylindrical bearing portions 75 of the composite joints sliding along the track member, the magnitude of the angular and sliding displacements occurring in the composite joint being determined by the extent of the lengthwise contraction of the sheath of the affected outer air muscle, 19c or 19d, as the case may be.

It will be evident that differential operation of the jack arrangements 61,63, will result in pivotal movement of the platform portion 27 about a roll axis, being an axis which is below the platform portion 27 and which extends in the fore and aft direction of the platform, the instantaneous position of the roll axis varying within limits depending upon the contributions of the two differentially operable jack arrangements, whilst remaining at all times below the platform.

The jack arrangements 61,63, are adapted for differential displacement, displacements of the jack arrangements in unison through identical displacements giving rise to'heave'motion of the seat platform portion 27, the amplitude of such heave motion being determined, as with all other motions of the first and/or second motion-director arrangements, by the amplitude of displacement of the motion-director arrangements and,

hence, of contractions in the lengths of the braided sheaths 85 of the air muscles 19a to 19d.

Whilst the jack devices 61a, 61b, are contra-rotated in raising the track members 47,49, the contra-rotation of the jacks devices, and the resetting of the air muscle responsible for the prior contra-rotation of the jack devices is achieved under gravity, the weight of a user bearing down on the platform portion 27 contributing to this.

Whereas the outer muscles are differentially operable to produce a desired roll effect in the platform portion 27 and, hence, the seat of which the platform is a part, operation of the inner muscles is mutually exclusive in character. When one air muscle, 19a, say, is activated to move the platform portion 27, the other 19b is to be quiescent.

So far as either of the inner muscles 19a, 19b, is concerned, expansion of the bladder 89 of the muscle creates, as with the outer muscles, a traction force, this acting, in the case of the inner muscles, by way of the pulley systems 95a, 95b, or either of them, at one or the other of the lugs 93a, 93b, depending upon which of the inner air muscles is activated instantaneously.

Activation of the muscle 19a applies a tractive force, by way of its associated pulley system 95a, to the platform portion 27, in the sense to propel the platform in the rearward direction as indicated, the platform being constrained by its coupling to the track members 47,49 for pivotal motion in one sense about an axis extending

transversely to the platform, the transverse axis being at a position above the platform portion 27. Similarly, activation of the air muscle 19b gives rise to a tractive force propelling the platform in the forward direction, the platform portion 27 pivoting about said transverse axis in the sense opposite to that given by action of the muscle 19a.

The track members being each composed of two straight inclined portions, the transverse axis about which the platform portion 27 swings varies intantaneously in position as the track members 47, 49, rock under the tractive force derived from one or the other of the inner air muscles 19a, 19b, this without taking into account the effect of movements of the tie-coupled jack devices 61a, 61b ; 61c, 61d, on the position of said transverse axis.

The track members 47,49, could, to achieve a nominally 'fixed'position for the transverse axis have been shaped as circular arcs. The choice of straight segmented track members is a matter of expedience and cost. The disturbances in altitude incurred in the position of the transverse axis as a result of the departure from the true circular arc are as will be appreciated, lost in the more prominent disturbances in both altitude and transverse attitude of the transverse axis attributable to the movements of the jack devices.

The position above the platform at which the transverse pivotal axis of the platform portion 27 is to be found at all times is determined, inter alia, by the contour of the track members 47,49.

Combined actions of variable amplitude in the first and second motion-director means, the track members 47,49, and the jack arrangements 61,63, that is to say, as determined by the controlled extent of inflation of the bladders of the air muscles, are capable of producing highly complex motion of the platform portion 27 in three dimensions under high and variable accelerations. Such complex motion of the platform involving, as it does, roll movement of the platform about a fore and aft axis below the platform as well as pitch motion about a transverse axis above the platform, the transverse spacing between the tie-coupled jack devices 61a, 61b and the tie-coupled jack devices 63a, 63b, varies in vertical projection with roll angle. It is to accommodate this variation that the jack members are permitted sliding motion with respect to the spindles 39a, 39b, on which they are mounted.

In the context of a simulation involving the manoeuvring of a road vehicle, the transverse pivotal axis is preferably to be found at an elevation above the head of an operator of the motion simulator apparatus when seated on a seat platform portion 27. For the avoidance of nauseous reaction to the platform motion it is recommended that the transverse pivot axis should not be at the ear level of the apparatus operator.

To accommodate the apparatus to variation in the length from the seat to the crown of the head of potential users of the apparatus, the transverse axis should at all times, preferably be at a position substantially above the head

of any such seated user.

The aforedescribed actions of the air muscles 19a to 19d in producing such complex motion in the motiondirector apparatus 17 are in response to inputs at manual means 105 of the seat, in directing the movement of a cursor having the form of a vehicle, on a raster scanned display, such as a c. r. t.

The aforesaid manual means 105 comprises a'steering' wheel 107 mounted on a pedestal 109, and'accelerator'and 'brake'pedals 111,113, respectively. The steering wheel platform 109, and said pedals 111,113, are supported, forward of the seating platform portion 27, rigid with said platform.

Referring to Fig. 12, the air muscles 19a to 19d are there diagrammatically represented as part of an error driven, closed loop, vehicle acceleration simulator system, the system comprising, in addition to said air muscles, the aforesaid sensors 21a, 21b; a digital computer 117; electrical interface means 119 including A to D converter 121, being electronic circuitry seat mounted within the housing 44a, is associated with the computer 117; pneumatic valve means 123; electrical and pneumatic supplies 125a, 125b, respectively; and a display device 127 for presenting raster scanned images of the motion of a vehicle.

The display presented at the display device 127 may, typically, be of a vehicle travelling along a highway at high variable speed and under high time varying acceleration, the user of the system, seated before the

display, notionally viewing the highway ahead as through the windshield of the vehicle. At the start of the simulation, the vehicle is stationary with respect to the highway. Depression of the accelerator pedal 111 causes the computer 117 to develop an output which causes the scene ahead, the highway with it, to appear to travel towards and past the vehicle from which the viewer is, notionally, viewing the scene ahead, fresh portions of the terrain ahead appearing, with the ever closer approach of near portions of the terrain ahead, to pass, notionally, to the rear of the vehicle.

The highway image may, in the forward scene, have tortuous bends such as may be encountered in the real world. Vehicle and other stationary images may be distributed along the notional highway. Other vehicle images may appear to be travelling along the highway towards the'observer'viewing the scene ahead.

The computer 117 receives outputs developed by transducers (not shown) in response to movements of the wheel 107 and/or the accelerator and brake pedals 111, 113, together with signals developed by the A to D converter 119 in response to outputs of the several sensors 21a, 21b, in the course of actuation of the several air muscles 19a to 19d and of the motion director mechanism 17.

In response to outputs from the aforesaid transducers associated variously with the air muscles 19a to 19d, the steering wheel 107 and accelerator and brake pedals 111, 113, the computer 117 develops outputs for controlling the

platform motion-director apparatus 17.

The electrical interface means 119 performs multiple tasks. It develops outputs serving to actuate various pneumatic valves (not specifically shown) associated with the several air muscles 19a to 19d, this in response to output signals developed at certain ones of said sensors 21 in the course of operation, and it activates various other sensors 21 such as to develop sensor output signals to serve as inputs to the A to D converter 119, all as directed by the computer software.

The computer software, overall, may be regarded as being in software functional blocks. In the diagram these are represented by flow diagram blocks labelled 129a to 129d.

Functional block 129a may be referred to a the physics engine of the system. It relates to logic operations to be performed on outputs from the transducers associated with the manual input means 105, being logic operations representative of algorithms descriptive of prescribed physical laws and phenomena to which a real vehicle might be subject in its movement over the terrain, along a highway, say.

The software of block 129a offers a model, among other matters, of speeds and accelerations resulting from the power developed by a real vehicle of given specification and performance, and of the outcome of encounters by the vehicle of events, random or otherwise.

The flow diagram block 129b may be referred to as the movement processor. It performs logic operations on data

arising as a result of logic operations at block 129a, producing data signals which are employed at flow diagram data comparator block 129c, together with feedback from sensors 21a and/or 21b, arrive at data employed at flow diagram block 129d in the development of valve actuation commands.

The software of block 129c serves as a comparator for the signals received thereat from the software functional block 129b and from the sensors 21. At the execution of a command by the platform motion-director mechanism 17, the sensor-derived output of the A to D converter 119 becomes diminishingly small, approaching the command signal in value, the output from the comparator 125c to the valve approaching a null.

In driving the comparator output, and hence, the output from flow diagram block 125d towards a null, data from flow diagram block 125d is utilized at the electrical interface means 123, to develop electrical signals of a character to actuate, as appropriate, the several pneumatic valves for the admission to and exhaustion from the air muscles 19a to 19d, of air under pressure, by way of the air passages 91 associated with the air muscles.

The several pneumatic valves are housed together with air pressure reduction means (not shown) from which air supplied thereto at an accurately controlled pressure of, in the example, 3 bar, for a period determined by the opening and closing of the relevant pneumatic valve or valves 19a to 19d, the consequent contraction in muscle sheaths 85, as appropriate, determining the extent of

pivotal displacement of the jack arrangements 61,63, or of the track members 47,49, as the case may be.

Digital signals, developed from analogue signals received at the A to D converter 119 from sensors 21, serve, as remarked earlier, as inputs to the comparator software of functional block 125c.

Movements of the manual input means, 107,111, 113, in executing the vehicle manoeuvres necessary to achieve the last stated goal give rise, as previously indicated, to outputs which, in accordance with the software with which the computer 117 is armed, cause the electrical interface means 123 to develop outputs serving to actuate pneumatic valve means, in a manner determined by the software, to create tractile movements of the air muscles, or any of them, such as to impart to the first and/or second seat motion-director means 47,49 ; 61,63, in due measure, motions, synchronous with the manoeuvres of the notional vehicle on travelling along the notional highway, being motions calculated to provide a good simulation of the accelerations to be expected in a real vehicle travelling a real highway nominally identical with that viewed.

Such computer simulations are commonplace, and it is known, moreover, to impart, to a system user seat, motions giving rise, in a system user, of physical sensations arising from accelerations akin to those that such person would experience were that person de facto driving a real vehicle in like manner in a like environment.

The system has been described broadly with reference to Fig. 12 in the context of a simulation of the sensations

experienced by the driver of a road vehicle driven at high speeds and with high accelerations along a highway. As remarked previously, the motion simulator apparatus of which the seat previously described is part has application not only to cars and other road vehicles, it has application also in the simulation of the'feel' experienced by the driver of a flight simulator.

Claims

CLAIMS 1. A motion simulator apparatus which comprises: simulator platform base; . a simulator platform for occupation by a user of the apparatus; coupling said platform base and said platform, . a platform motion-director mechanism; and also coupling said platform base and said platform, . a multiplicity of independently operable actuators; and, . motion-director mechanism manually operable input means; and in which, . the aforesaid parts of the apparatus are constructed, arranged and adapted such as, in operation, to cooperate to produce in said platform, a composite motion with respect to said base, being a composite motion derived from the several motions to which said platform motion-director mechanism may, instantaneously, be subject, as a result of action of said actuators, or any of them, together or separately, and being such that said platform is constrained: .. for pivotal motion with respect to said platform base about a transverse first axis, the instantaneous position of which is to be, at all times, substantially above the platform; and, concurrently with said pivotal motion about a transverse axis, .. for pivotal motion about a fore and aft-extensive second axis, the instantaneous position of which is, at all times, not to be substantially above the platform.

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2. A motion simulator apparatus as claimed in claim 1 in which said mechanism is such that said transverse axis is constrained in such manner as never to occupy a position substantially below the ear level a notional platform occupant.
3. A motion simulator apparatus as claimed in claim 2 in which said platform constitutes the seating platform of a seat having a seat back member.
4. A motion simulator apparatus as claimed in claim 1,2 or 3 in which said platform motion-director mechanism comprises: . integral with said platform, a first platform-motion director means, being platform-motion director means comprising: .. first and second laterally spaced, fore-and-aft extensive, track members of corresponding longitudinal contour, the longitudinal axes of said track members being contained in parallel planes; and, coupled to said track members and to said platform base, a second seat-motion director means comprising: first and second independently operable jack arrangements, being jack arrangements constructed, arranged and adapted and being operable such as to constrain said first and second track members, respectively, for independent displacement thereof, in elevation, with respect to said platform base; and in which: . the couplings between said first and second

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independently operable jack means and said track members and the couplings between said independently operable jack means and said platform base are such as to permit sliding of the track members in unison with respect to said jack means, and, hence, said platform base over the range of permissible independent displacements of each of the several said jack means.
5. A motion simulator apparatus as claimed in claim 4 in which: the individual couplings between said jack members and said track members each comprise a ball joint and a cylindrical bearing adapted to receive a track member, being a cylindrical bearing the longitudinal axis of which is coincident with a diameter of said ball joint.
6. A motion simulator apparatus as claimed in claim 4 or 5 in which said first and second independently operable jack arrangements pivotally coupled to said platform base, each said jack arrangement comprising first and second jack devices ganged together by tie members coupling the devices together such that the coupled jack devices are constrained for equal and opposite angular displacement with respect to said platform base.
7. A motion simulator apparatus as claimed in claim 4,5, or 6 in which said first and second track members each comprise first and second rectilinear contiguous track members inclined with respect to one another to meet endto-end.

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8. A motion simulator apparatus as claimed in any of claims 4 to 7 in which: said platform base incorporates interface adaptor means to which the several said jack devices are coupled.
9. A motion simulator apparatus as claimed in claim 8 in which: said adaptor means has spars, one for each jack means, said spars projecting laterally from the body of said adaptor means, and the several said jack means being both axially slideable with respect to their respective said spars and angularly displaceable with respect to the longitudinal axes of said spars.
10. A motion simulator apparatus as claimed in claim 9 in which said adaptor means comprises first and second parallel beam members from which said spars project, and, between said beam members, first and second parallel cross-strut members, the beam members being rigid with said cross-strut members.
11. A motion simulator apparatus as claimed in any one of claims 4 to 10 in which first and second ones of said actuators are connected between said base and said platform in an arrangement such that, upon actuation thereof, said first actuator acts on said platform in a sense to cause said track members to slide in one direction with respect to said base, and upon actuation thereof, said second actuator acts on said platform in a sense to cause said track members to slide in the opposite direction with respect to said base, the platform, by

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virtue of its rigid connection with said track members, being correspondingly displaced in sympathy with said movements of said track means.
12. A motion simulator apparatus as claimed in claims 9 or 10 and 11 in which said first and second actuators are coupled, the one at one end to one of said cross-struts, the other at one end to the other of said cross-struts, the other ends of said first and second actuators being coupled to the platform at or adjacent to the forward and rear ends, respectively, thereof.
13. A motion simulator apparatus as claimed in claim 12 and which comprises actuator displacement multiplier means, being first and second pulley systems respectively associated with said first and second actuators, each said pulley system comprising first and second pulley means, said first pulley means of each of said first and second pulley systems being carried by and being rotatable with respect to said other end of said first or second actuator, as the case may be, said second pulley means mounted on and rotatable with respect to said crossstruts, and a substantially inextensible elongate member, of a limp material, extending around said first and second pulley means and being connected at one end to said actuator at said other end thereof, and, at the other end to said platform or other part integral with said platform.

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14. A motion simulator apparatus as claimed in any of claims 4 to 13 in which third and fourth actuators are respectively connected between said first and second jack devices of said first or second independently operable jack arrangements, actuation of said third or fourth actuator producing pivotal movement of opposite sense of the jack members of said first or second jack arrangement, as the case may be, with consequent change in elevation of the first or second track member, as the case may be.
14. A motion simulator apparatus as claimed in any preceding claim in which: said actuators are constituted by air muscles, the air muscles coupling together said first and second jack devices of said first and second jack arrangements are adapted to be restored from the contracted to the extended state under gravitational force exerted on said platform.
15. A simulator system for simulating the sensation experienced by the occupant of a vehicle whilst following a track, being a system which comprises: a motion simulator apparatus as claimed in any preceding claim; display means; data processor means; a multiplicity of sensor means operative to develop outputs respectively representative of instantaneous states of the several said motion simulator actuators; and, manual input means; and in which:

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said data processor means is programmed such as to cause cues for the movement of a vehicle-representing cursor in the performance of a cursor tracking task simulating the movement of a vehicle, to be presented at said display means, being cursor movement to be effected in response to signals derived from inputs at said manual input means; and, in response to output signals developed by said sensors as a result of input movements at said manual input means, said actuators are to be caused, in the tracking by said cursor of said cues, to impart motions to said first and second motion-director means such as to produce motions in said seat part such as to convey to an occupant of said seat part, a sensation akin to that which would be experienced by the occupant were the cursor a vehicle and the occupant an occupant thereof.
16. A motion simulator apparatus substantially as hereinbefore described with reference to the accompanying drawings.
17. A simulator system substantially as hereinbefore described with reference to the accompanying drawings.