IMPROVEMENTS RELATING TO MOTION GENERATORS

Abstract: A motion generator, for a fairground ride for example, is designed to provide complex movement with a selection of linear degrees of freedom (surge, sway and heave) and with a selection of rotary degrees of freedom (roll, pitch and yaw). There is a sequence of members, a first member (6) carried by a base (1), a second member (10) carried by the first member (6) and so on, either through swinging arms (2; 9) for approximately linear motion or by journals (14) for rotary motion. The base (1) and all but the final member of the sequence have rotary drive units (15, 18, 21) which couple to the succeeding member (6, 10, 13) to impart one of the motions. These drive units can be under computer control.

Description: 1 Improvements relating to Motion Generators This invention relates to motion generators. It is primarily intended for simulating rides, either for amusement or for training. These are well known, but complex and costly. It is generally considered desirable to offer most if not all the six theoretically possible degrees of movement, which are: Linear - Surge (fore and aft) Sway (sideways) Heave (up and down) Rotational - Roll (about a horizontal fore and aft axis) Pitch (about a horizontal transverse axis) Yaw (about a vertical axis) It is usual, particularly for the linear movements, to employ sliding joints. Hydraulic actuators are commonplace as the drive units, but pneumatic ones may be used, as well as electromagnets and electric motors . Computer control can activate these in all manner of combinations to give a complex motion. It is the aim of this invention to eliminate sliding joints and linear actuators and to produce a simpler, less costly motion generator, but one equally susceptible to computer control . According to the present invention there is provided a motion generator comprising a fixed base and a member carried by the base and forming the last of a sequence of 2 mobile members, each member having, at least as the main component of its permitted motion with respect to the base or the member immediately preceding in the sequence, to which it is pivotally connected, one of said degrees of freedom, each degree being different through the sequence, and rotary drive units, carried by the base and each member of the sequence except the last one, respectively coupled to the member succeeding in the sequence and to the said last member to impart said permitted motions under computer control. The three rotational degrees of freedom present no problem and can be achieved by direct pivoting of one member to another. But the three linear degrees of freedom may be approximated by connecting one member to the next by making a parallel or four bar linkage. The longer those arms, the "flatter" is the arc of movement of the downstream member and the more it approximates to rectilinear motion. This will be acceptable for most practical purposes. When one member is elongate and its motion relative to the immediately preceding member or the base is transverse to its length, said one member may be carried by said arms at one end and by a pivot at the other end. The transverse movement will then be arcuate about the pivot . So if the elongate member has sway imparted by the arms at one end, it also has an element of yaw imposed by the pivot. However, if the length is substantial, the angle of yaw will be small and to someone at the arms' end the predominant motion will be sway. For practical purposes, the member can be regarded 3 as having one of the linear degrees of motion. This can considerably reduce the amount of structure, a single pivot being much simpler and more compact than swinging arms from a supporting frame. It is not necessary for many applications to provide all six degrees of freedom and a selection may be made. Generally, it will be convenient to have the "linear" ones first in the sequence and then the rotational ones. Thus , in one preferred form three degrees of freedom are offered: surge, sway and roll. These are suitable for vehicle driving simulations. The first member of the sequence is suspended by swinging arms from the base and the second member of the sequence is suspended by swinging arms from the first member, the pivot axes all being horizontal, with those of the second set of arms at right angles to those of the first set. The last member is directly pivoted to the second member of the sequence, the pivot axis being horizontal . Either the first or second member could be the elongate member referred to above, carried by arms at one end and a pivot at the other. Generally the arms of each set will be parallel, but if desired they could be non-parallel, making a four bar linkage that would introduce into the surge motion, for example, an element of pitch and into the sway motion an element of roll . For a better understanding of the invention, one embodiment will now be described, by way of example, with 4 reference to the accompanying drawings, in which: Figure 1 is a side elevation of a motion generator, Figure 2 is a perspective view of one end of the generator, with some parts omitted, Figure 3 is a perspective view of that one end from another angle with other parts omitted, and Figure 4 is a perspective view of the opposite end of the generator with further parts omitted. The apparatus has an elongate rectangular base 1 with pairs of triangulated upright sub- frames 2 at opposite ends. The tops of these sub-frames have journals 3 for suspending further sub-frames 4 which can swing in the longitudinal direction of the base between the associated sub-frames 2. They carry, through journals 5 at their lower ends, another frame 6, referred to herein as the surge frame, and this has a pair of triangulated upright sub-frames 7 at one end joined by a cross-bar 8 at the top. Two arms 9 are pivoted to and hang down from this cross-bar, one on each side of the surge frame 6 and can swing transversely to the frame and hence to the base 1. They carry between them at their lower ends the rear end of a frame 10, referred to herein as the sway frame. There could be a similar swinging suspension at the forward end of the sway frame, but to simplify the construction that end is pivoted, using a spherical bearing 11, on the centre line of the surge frame. This allows the transverse swing or sway of the rear end of the frame 10 where the payload 12 will be while accommodating the slight up and down movement at that end imposed by the 5 links. The sway frame 10 carries a platform 13 pivoted by journals 14 about a central longitudinal axis between the ends of the frame 10. This will be referred to as the roll platform and the payload 12 is carried by it. There are therefore the following possible motions, alone or in combination: 1) . Surge, when the frame 6 swings backwards and forwards. If the sub- frames 4 are parallel, there will be a small amount of heave, while if they are not there will be traces of heave and pitch. 2) . Sway, when the frame 10 swings from side to side. There will be a bit of yaw by virtue of the pivot 11, and a negligible amount of heave. 3) . Roll, when the platform 13 tilts about its longitudinal axis. They can be generated and controlled by respective motors and control units . The surge motor 15 is mounted on the base and couples to the surge frame 6 through an arm 16 and connecting rod 17, as best seen in Figure 2. As the arm 16 swings, so the rod 17 pushes and pulls the frame 6 longitudinally of the base 1. The sway motor 18 is mounted between the sub-frames 7 and couples to the sway frame 10 through an arm 19 and connecting rod 20, as best seen in Figure 3. As the arm 19 swings so the rod 20 pushes and pulls the rear end of frame 10 sideways of the frame 6 and thus of the base 1. The roll motor 21 is mounted on the surge frame 6 at 6 the end opposite the sway motor 18 and couples to the platform 13, to one side of its longitudinal axis, through an arm 22 and connecting rod 23, as best seen in Figure 3. As the arm 22 swings, so the rod 23 tilts the platform 13. The control units 24 for all these motors can be grouped together on a bracket 25 attached between one of the pairs of sub-frames 2, as seen in Figure 2. The motors themselves are conveniently standard 3 -phase electric motors with standard speed controllers, which provide position control by potentiometer feedback. It will be understood that there can be differences in the order in which the various frames and platforms are arranged. For example, sway may come before surge in the sequence from the base. But generally, the "linear" motions will precede the rotational ones.

Claims: 7 Claims 1. A motion generator comprising a fixed base and a member carried by the base and forming the last of a sequence of mobile members, each member having, at least as the main component of its permitted motion with respect to the base or the member immediately preceding in the sequence, to which it is pivotally connected, one of said degrees of freedom, each degree being different through the sequence, and rotary drive units, carried by the base and each member of the sequence except the last one, respectively coupled to the member succeeding in the sequence and to the said last member to impart said permitted motions under computer control . 2. A motion generator as claimed in claim 1, wherein at least one of the three rotational degrees of freedom is achieved by direct pivoting of one member to another. 3. A motion generator as claimed in claim 1 or 2 , wherein at least one of the three linear degrees of freedom is approximated by connecting one member to the next by arms, making a parallel or four bar linkage. 4. A motion generator as claimed in claim 3, wherein one member is elongate and its motion relative to the immediately preceding member or the base is transverse to its length, and wherein said one member is carried by said arms at one end and by a pivot at the other end, whereby the transverse movement is arcuate about the pivot. 5. A motion generator as claimed in any preceding 8 claim, wherein linear degrees of freedom precede the rotational ones in the sequence. 6. A motion generator as claimed in any preceding claim, wherein there are less than six members. 7. A motion generator as claimed in claim 6, wherein there are three members giving three degrees of freedom, surge, sway and roll. 8. A motion generator as claimed in claim 7, wherein the first member of the sequence is suspended by swinging arms from the base and the second member of the sequence is suspended by swinging arms from the first member, the pivot axes all being horizontal, with those of the second set of arms at right angles to those of the first set, and wherein said last member is directly pivoted to the second member of the sequence, the pivot axis being horizontal. 9. A motion generator as claimed in claim 8, as appendant to claim 4, wherein either the first or second member is said one, elongate member. 10. A motion generator as claimed in claim 8 or 9, wherein the arms of each set are parallel. 11. A motion generator as claimed in claim 8 or 9, wherein the arms of the set which generates surge are non- parallel, making a four bar linkage that introduces into the surge motion an element of pitch. 12. A motion generator as claimed in claim 8, 9 or 11, wherein the arms of the set which generates sway are non- parallel, making a four bar linkage that introduces into the sway motion an element of roll.

Inventors: MCCALLUM IAN REID, MCCALLUM, IAN, REID
Applicants: MCCALLUM IAN REID, MCCALLUM, IAN, REID
Application year: 1999
Main classification: A63G31
IPC codes: A63B22, A63B26, A63G9, A63G31