GB2179605A - Motion simulator - Google Patents

Description

1 GB 2 179 605 A 1

SPECIFICATION

Motion simulator 4 v 1 50 This invention relatesto motion simulator systems 70 and more particularlyto a ground vehicle motion simulator system.

When training peopleto control such thingsas aircraftand largevehicles it is more convenientto begin with simulated experience before embarking on expensive and potentially less safetraining on the real thing. Forthis purpose simulators have been developed.

The simulation of motion by means of a simulator relies partially upon thefactthatthe human brain can be influenced into experiencing apparent motion by a combination of momentary accelerations, inclina tions of the body and visual effects.

In simulating ground vehicles it is necessaryto represent, not onlythe motion of the vehicle butalso sometimes severe attitudes induced bytheterrain overwhich the vehicle is supposed to betravelling.

To achievethis simulation of motion there are cur rently several simulated motion systems forvarious applications. One of these is a synergistic six degrees of freedom (6 D.O.F.) system,which is primarily used forsimulating the flying characteristics of aircraft.

The six degrees of freedom are pitch, roll, yaw, surge, sway and heave. Also there arethree degrees of free dom (3 D.O.F.) systems which are derived according tothe characteristics required to be simulated and are adequate in the simulation of the principal character istics of some single seat light aircraft and ground vehicles.

6 D.O.F. systems are usually designed with the 100 simulation of acceleration in mind as well asthe simulation of attitude. This acceleration simulation is acheived by accelerating thetrainee awayfrom a mean position on the simulator and graduallyfading them backto the mean position; a procedure known as'washing out'. As ground vehicle development has progressed, the need to provide more complex and expanded training programs has increased. This has to be reflected in the performance of motion simula tion systems. Thusfor ground vehicles, a motion simulation system must be capable of providing both the simulation of the supposed terrain (static) andthe characteristics of the vehicle in reaction thereto (dynamic), i.e. pitching, rolling, yawing and heaving, whilst still achieving the simulation of longitudinal accelerations clueto the vehicle acceleration, braking, gearchanging and the like. Natural physical limits occur in the use of synergistic motion systems which prevent such longitudinal acceleration simulation without it adversely affecting the quality of the simu lation of the various other effects.

Previous synergistic 6 D.O.F. systems will simulate the general terrain effects, whether static or dynamic, as feitthrough vehicle suspension, but may not pro vide the additional requirements of acceeleration or surge on top of this, particularly when at extreme attitudes.

The current 3 D.O.F. systems have f ixed centres of rotation. This particularly limits their ability to place the driver in the correct relationship with respect to the simulated vehicle centre of rotation. This is not the case in a 6 D.O. F. motion system asthe instantaneous centre of rotation may be in any position. 3 D.O.F. motion systems also sufferfrom the disadvantagethatthey may not settle in a level position when the powersystem malfunctions, hence a level of agility may be required bythe traineeto enable him or her to evacuate the vehicle. Furthermore, such fixed centres of rotation in 3 D.O.F. systems only allow pitch- ing, rolling and yawing effects in addition to the static ground effects. Dynamic ground effects, such as heaving, and surge effects, such as braking, acceierating and gear changing, can only be added via the pitch axis which is not strictly realistic.

Thus, according to the present invention there is provided apparatus for simulating motion comprising a main frame, a plurality of extensible and retractable legs, each leg being secured to the main frame at one end thereof by means of a corresponding univer- sal pivot and independently actuated to extend and retract by leg actuating means, a foot, secured to the other end of each leg by means of a further corresponding universal pivot, anchoring the other ends of the legs in their relative positions, and a surgeframe slidably mounted on a straighttrack on the main frame and actuated to move on the track by means of frame actuating means.

A specific embodiment of the invention will now be described byway of example with reference to the accompanying drawings in which:

Figure 1 is a schematic diagram of a motion simulator incorporating the invention, and Figure2 is an exploded view of the frames of Figure 1 and illustrating the mounting position of a suitable cabin.

Referring to the figures, a main frame 10 is supported on a set of six extensible and retractable legs 11. Each leg 11 is secured at one end to the underside of the frame 10 by means of a corresponding univer- sal pivot (not shown) to define a generally triangular shape, such thatthe ends of a pair of legs 11 is located nominally at each vertex of the generally triangular shape. Each leg 11 from one vertex is secured at its other end to a foot 12, along with the adjacent leg 11 of an adjacentvertex, also by means of a corresponding universal pivot 13.

The legs 11 are independently actuated such that the attitude of the frame 10 is variable according to the relative extension and retraction of each leg 11. As such,the frame is able to simulate motion according to the basic 6 D.O.F. system which, in this embodiment, is designed around a motion leg extension with the abilityto achieve 30.060 of pitch.

The main frame 10 hasthree halves 14 of three linear bearings mounted on its upper surface,the axis of each bearing half 14 being in the fore/aft direction of the frame 10. The other half 15 of each bearing is attached to the underside of a surgeframe 16. With the corresponding halves 14 and 15 of the bearing cooperating the surge frame 16 is f reeto movefore and aftwithin the bearing limits.

The surgeframe 16 is moved on the linear bearings by means of an independently actuated hydraulic piston and cylinder device 17. The cylinder isfixedly securedtothe mainframe 10 bya trunnion 19 andthe 2 GB 2 179 605 A 2 piston is connected with the surge frame 16 bya piston rod 18. A driver's cabin 20 is rigidly secured to thesurgeframe 16 such that a trainee will experience the supplementary surge effects inthedirection heis 5 facing atthattime.

The surgeframe 16 is symmetrically disposed aboutthe mainframe roll axiswith the longitudinal actuator 17 being mounted directly above the roll axis.When the main motionframe 10 is driven inthe modes of pitch, roll,yaworheave etc., oranycombination of these,the actuator 17 can be driven separateiyto provide acceleration cues, in the direction of motion being simulated atthetime, withoutdegradation of the other motion cues.

Signals to drivethe longitudinal actuator 17 will be generated either bythe operation of an accelerator, footbrake orgearselector. Translation of the signals will be via pre-programmed softwarewhich controls the movement of the actuators.

Claims (6)

1. Apparatus for simulating motion comprising a mainframe, a plurality of extensible and retractable legs, each leg being secured to the mainframe, ata first end thereof, by means of a corresponding universal pivot, and secured at the second end thereof, by means of a further corresponding universal pivot, to a foot such that the second end of each leg is anchored in a fixed position relative to the second ends of the remaining legs, leg actuating means, actuableto extend and retract each leg independently, and a surge frame si idably mounted on a straight track on the main frame and actuated to move on the track by means of frame actuating means,

2. Apparatus as claimed in claim 1, wherein the frame actuating means area hydraulic piston and cylinder device the cylinderthereof being secured to the mainframe atone end and a piston rod connected with the piston being secured to the surge frame frame atthe other, such thatthe axis of the device is substantial iy parallel to that of the track.

3. Apparatus as claimed in claim 1 or 2, wherein six extensible and retractable legs are secured to the underside of the mainframe in a genrallytriangular formation such that each vertex of the triangularformation is generally defined by the one ends of a pair of legs.

4. Apparatus as claimed in claim 3, wherein a pair of adjacent legs from adjacent vertices of the triangularformation converge to be secured to a common foot.

5. Apparatus as claimed in any of the preceding claims, wherein a seating arrangement and appar- atus control means are fixedly mounted on the surge frame.

6. Apparatus substantially as described herein with reference to the accompanying drawings.

Printed for Her Majesty'sStationery Office by Croydon Printing Company (UK) Ltd, 1187, D8817356. Published byThe Patent Office, 25 Southampton Buildings, LondonWC2A lAY, from which copies may be obtained.

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