WO2000074622A1

WO2000074622A1 - Transport means

Info

Publication number: WO2000074622A1
Application number: PCT/GB2000/002247
Authority: WO
Inventors: Maurice Andrew Jackson; Chandru Ray
Original assignee: The Royal Wolverhampton Hospitals 'nhs Trust; Thama Holdings Limited
Priority date: 1999-06-09
Filing date: 2000-06-09
Publication date: 2000-12-14
Also published as: AU5543400A; GB9913302D0; EP1185228A1

Abstract

A mobility aid (e.g. for use by infirm or disabled persons) comprises (a) an elongate frame member (2) having front and rear portions relative to the predominant direction of motion of the mobility aid; (b) a pair of first rotatable support members (10) operatively associated with said front portion; (c) a single second rotatable support member (3) operatively associated with said rear portion; and (d) steering means (12; 13; 14) adapted in use to change the direction of motion of the mobility aid. Each of the rotatable support members (b) and (c) may be capable of being independently driven, for example by means of electric motors (a) powered by one or more rechargeable batteries (8), all of which are mounted on the mobility aid.

Description

TRANSPORT MEANS

This invention relates to transport means and especially to transport means adapted for use by infirm or disabled persons. Although the present invention will be described hereinafter with particular reference to mobility aids for such persons, it is not to be construed as being limited thereto.

Some patients are capable of travelling only 20-30 yards without experiencing symptoms such as shortness of breath and/or pain. Such patients include, for example, amputees, those suffering from diseases such as asthma, arthritis and angina pectoris, or those born with a physical disability. Other conditions which can adversely affect mobility include: hemiplegia; severe osteo-arthritis of hip or knee; peripheral vascular disease; a history of poliomyelitis; chronic obstructive pulmonary disease; multiple sclerosis; major orthopaedic trauma; and multiple fractures.

Known mobility aids such as powered wheelchairs are heavy, bulky, cannot be stored or folded and cannot easily fit into a car. Powered wheelchairs are in general intended to have a travelling-range of 20 miles or more.

Lightweight, manually operated, wheelchairs are known but operation of these requires a relatively high level of arm function and physical fitness. The user needs to be trained in their operation, and to practise over several months. Hence, these wheelchairs are suitable only for use by the long-term disabled. Furthermore, known mobility aids neither make use of, nor assist, nor encourage development of the user's leg function. Legs are stronger than arms and more capable of effecting propulsion. Many of the conditions described above are temporary or capable of improvement. For these conditions, it is highly desirable to encourage walking as an integral part of the use of a mobility aid.

Powered wheelchairs and other mobility aids need to be highly manoeuvrable within a small space. Known aids are turned by steering the front or rear wheels. Increase in manoeuvrability can be achieved by shrinking the wheelbase of the vehicle i.e. by bringing the front wheels closer to the rear wheels. This requirement conflicts with the need for a stable aid which adequately and safely support the user over a variety of terrain. One method of achieving this stability with manoeuverability has been to increase the weight of the aid.

The present invention aims to provide a mobility aid which can be readily deployed and readily stored. A patient who has the use of a car may only require a mobility aid with a relatively short travelling-range (say 3-4 miles) , but such a mobility aid must be capable of being deployed by a patient with physical disability or infirmity.

The present invention uses a different approach to meet the manoeuvrability, stability, and treatment oriented goals of a mobility aid. It thereby achieves increased performance, and avoids traditional engineering compromises.

Accordingly, the present invention provides transport means comprising; (a) an elongate frame member having front and rear portions (relative to the predominant direction of motion) ;

(b) a pair of first rotatable support members operatively associated with said front portion;

(c) a single second rotatable support member operatively associated with said rear portion; and

(d) steering means adapted in use to change the direction of motion of the transport means.

Preferably, transport means according to the present invention is capable of being used in more than one mode. For example, a patient may "sit on" the device as a passenger or may, in suitable circumstances, use the device in the manner of a "scooter" by assisting propulsion from a "standing" position.

Preferably, the first rotatable support members (b) comprise wheels. For example, the first rotatable support members may consist of a pair of wheels mounted on and being rotatable about a common axle, and the axle may be pivotally connected to the elongate frame member (a) .

Preferably, the first rotatable support members (b) are adapted to be powered (e.g. by means of a motor driven by one or more batteries) . In a particularly preferred embodiment of the present invention, at least two of the first rotatable support members (b) are adapted to be powered in opposed circumferential directions relative to each other (i.e. independently driven) . In a particularly preferred embodiment the steering means is adapted to rotate the first rotatable support members (b) at different speeds (and/or in different directions) in order to change the direction of motion of the transport means.

If the first rotatable support means are individually or independently powered, they are mounted on and rotatable about an axle or other mounting means which may be fixed relative to the elongate frame. In a preferred embodiment, the mounting means is an axle which is fixed at right angles to the elongate frame to form a T-shaped or substantially T- shaped framework.

By varying the speed of rotation of one rotatable support means relative to the speed of rotation of other rotatable support means in the pair, the transport means may be steered either to the left hand side or the right hand side, relative to its direction of travel. For example, when turning (and where the first rotatable support means comprise a pair of wheels) the wheel located on the same side of the transport means as the intended direction of steering may stop rotating, or be powered in reverse. The other wheel of the pair, disposed on the opposite side of the transport means, may continue to be powered in a forwards direction, or the power to this wheel in the forwards direction may be increased to effect a tighter turn.

Preferably, the second rotatable support member (c) may comprise a ball- castor. Alternatively, the second rotatable support member (c) may comprise a wheeled castor. The single second rotatable support member, operatively connected at said rear portion of the transport means, allows rotation of the transport means about the second rotatable support member and the ability to swivel the transport means from a stationary position (i.e. with no forward motion needed beforehand) to select the direction of travel before moving forwards if desired. Alternatively, the second rotatable support member (c) may be fixed in position.

Preferably, the second rotatable support member (c) is adapted to be powered. In a particularly preferred embodiment of the present invention, the second rotatable support member (c) may be steerable. By means of such powered steering, torque may be applied between the member (c) and the surface over which it moves, thereby increasing the stability of the transport means.

Transport means according to the present invention may suitably be provided with a seat. The seat may be operatively associated with the elongate frame member (a) .

Preferably, the seat is adapted so as to be capable of adjustment of its height and position, relative to the elongate frame member (a) .

The steering means (d) may suitably comprise an elongate rod operatively associated with the common axle of the support members (b) . The rod may be adapted to be rotated about its longitudinal axis. Alternatively, the rod may be fixed and the steering provided by means of the powered wheels only. Preferably, the rod may be provided, at its end remote from the support members (b) , with hand-grips or handlebars. These may be adapted to support the user by the forearms, the elbows, the shoulders or the front part of the body.

Preferably, the length of the rod may be made variable, for example by making the rod to have two or more articulated or telescoping portions. Thus, the height of the steering means (d) relative to the frame member (a) will be adjustable. The steering means (d) may be provided with powered movement (e.g. by means of a motor driven by one or more batteries) . Preferably, only the pair of first rotatable support members is powered. Additionally or alternatively, powering of the transport means may be assisted or provided by the user supporting some of his weight on the seat and using a trailing leg to push the transport means forwards. The single second rotatable support member allows the trailing leg to assist powering of the transport means without catching or otherwise impeding the trailing leg.

Suitably, the powered movement may be actuated by manually-operable switching means such as a "joystick" and associated electronic components.

In a preferred embodiment, the elongate rod is not rotatable about its longitudinal axis and is fixed to the frame. Each member of the pair of first rotatable support members is, in the preferred embodiment, independently driven and the switching means varies the power supply to vary the rotation speeds of each of the first rotatable support members, effecting a desired steering direction. Suitably, a moveable joystick may be the switching means, the joystick being operatively connected to suitable electronic components.

The frame member (a) may conveniently be made of a metal. It may suitably be of hollow, generally tubular construction, for example of circular, elliptical or oval transverse cross-section. In an especially preferred embodiment of the present invention, the frame member (a) may be adapted to be reduced in overall dimensions, e.g. by having one or more articulated or telescoping portions so that the frame member (a) is effectively "foldable" for storage or removal. The frame member (a) may be further provided with means to receive one or more batteries for powering the rotatable supports (b) , and/or one or more electric motors, together with associated electronic components and circuitry. This may be achieved, for example, by providing one or more housings on the frame member (a) .

The aforesaid electronic components can conveniently include a charger for the batteries. A further housing may be provided for this purpose and can be located on the frame member (a) . If the transport means is used as a "scooter" , the manual power supplied by the user may assist charging of the battery.

The frame member (a) may optionally be provided with one or more foot- supports (running-boards) for the convenience of the user.

The frame member (a) may further be provided with means to adjust the height of the frame member (a) relative to the ground.

Similar means may be provided to adjust the height of a seat (when fitted) relative to the frame member (a) .

The seat may comprise one or a plurality of seats adapted to be fitted to and supported by seat support means.

The seat support means preferably comprises an elongate member which may be adapted to be extendible and/or retractable in length. The elongate member may therefore suitably comprise a rod with articulated or telescoping portions. The elongate member may, at its base, be movable relative the frame to a plurality of possible positions to allow the distance between the seat and the steering means to be adjusted. The seat support means may fold towards the frame to a more compact position prior to storage of the transport means.

Alternatively, the seat may be mounted on a central portion of an elongate, substantially C-shaped or curved, member which is rigid enough to support a person's weight. Each end of the rigid elongate member may be fixed to the frame so that the seat is supported at a height therefrom.

A gear-train may further be provided to transmit motive power from the electric motor to the front wheels. Preferably, this will be a reducing gear-train.

Where the transport means is to be used in the manner of a "scooter" , any foot-support (running-board) fitted may be so configured as to provide clearance for the heel of the user at the rearward end of the frame member (a) .

In another aspect, the present invention provides transport means comprising: (a) an elongate frame member having front and rear portions;

(b) a first rotatable support member operatively associated with said front portion;

(c) a second rotatable support member operatively associated with said rear portion; and (d) support means for a user, said support means being capable of adjustment from a first portion wherein the centre of gravity of the transport means in use is substantially operatively associated with the front portion of the frame member (a) to a second position wherein the centre of the gravity of the transport means in use is substantially operatively associated with the rear portion of the frame member (a) . In a further aspect the present invention provides a program on a carrier, the program being adapted to effect control of the transport means, e.g. by rotating at least two of the first rotatable support members at different speeds and/or in different circumferential directions relative to each other.

Preferred embodiments of the present invention will be illustrated, merely by way of example, in the following description and with reference to the accompanying drawings. In the drawings:

Figure 1 is a schematic perspective view of transport means according to a first embodiment of the invention;

Figure 2 is a side view of a second embodiment of the invention;

Figure 3 is a top view of the embodiment of Figure 2;

Figure 4 is a front view of the embodiment of Figure 2;

Figure 5 is a side view showing transport means according to the invention, in relation to a typical user;

Figure 6 is a rear view of transport means according to the invention, in relation to a typical user;

Figure 7 shows schematically an alternative embodiment of the second rotatable member;

Figure 8 illustrates schematically how, in transport means according to the invention, the seat support may be adjustable; and Figure 9 shows schematically an electronic control system according to the present invention.

Referring to Figure 1 , the transport means comprises a generally elongate frame 2 formed from a folded length of metal tubing having two substantially parallel elongate portions 2a, 2b. At the rear end of the frame there is a looped portion of tubing into which is mounted a rotatable castor 3 in the form of a ball member. The ball member is mounted so as to be rotatable in any direction about the point X.

Towards the front of the frame 2, wheel mounting means 4 in the form of folded metal tubing is fixed by welding to the frame. As can be seen from the figure, the strength of the welding connection is improved by welding the wheel mounting means at four positions on the two lengths 2a, 2b of the frame where the wheel support means and frame overlap. The welding connection defines a cavity 5. The framework which results from the welding connection between the frame 2 and the wheel mounting means 4 is generally T-shaped.

The wheel mounting means 4 is folded so as to be symmetrical about the elongate frame 2, forming two identical enclosures 6 and 7. In each of the enclosures 6 and 7, there is located and supported a battery 8, and an electric motor 9, together with electronic components to operatively connect a battery to each motor. The spatial arrangement of one battery and one motor on either side of the frame 2 provides ballast to and confers balance on the transport means 1.

A wheel 10 is fitted to each end face 11 of the wheel mounting means 4. Each motor 9 operatively engages a wheel 10 so that the motor can drive its associated wheel in either circumferential direction, and so that each wheel is driven independently of the other.

An elongate rod 12 extends perpendicularly upwards from the plane of the frame 2 and wheel mounting means 4. The base of the elongate rod 12 is inserted into the cavity 5 and fixed to the frame and/or wheel mounting means by, for example, welding. The elongate rod 12 has, at its end remote from the frame, a cross bar 13 with handle grips 14 fixed at each end of the cross bar.

Between the handle grips 14, there is located a steering control 15 which includes manually operated switching means in the form of a joystick 16. The steering control 15 is located at the junction of the elongate rod 12 and cross bar 13.

Suitable electronic components and wiring operatively communicate movements of the joystick 16 to the motors 9. Ideally, the elongate rod 12 is hollow, so that wiring can be passed through the rod 12 and emerge from its base to engage each motor 9.

The rod 12 is capable of a telescoping action owing to two telescoping components which allow adjustment of the height of the cross bar 13 relative to the frame 2. When the transport means 1 is not in use, for example when being transported in a vehicle, the rod 12 may be folded in the direction indicated by arrow 17, pivoting about a connection with the frame 2. In the folded position, the rod 12 lies against the frame 2. The folding may be effected by releasing a lock and catch mechanism (not shown) to allow the rod to fold against the frame 2. A seat 18 is detachably fitted to one end of a seat support rod 19. The opposite end of the seat support rod 19 is fixed to a slide member 20 which is located between parallel lengths of tubing 2a, 2b of the frame 2. The slide member 20 is moveable along the length of the frame between the two lengths of frame 2a, 2b. Once a position along the length of the frame has been selected, the slide member 20 can be locked to secure the seat 18 and seat support rod 19 in position. The lock (not shown) may be in the form of a nut or rotatable piece on the underside of the slide which can be tightened to effect locking of the slide member 20 relative to the frame 2.

The seat support rod 19 comprises two telescoping portions which allow adjustment of the height of the seat 18 relative to the frame. A locking mechanism (not shown) allows the length of the seat support rod 19 to be fixed, securing the seat 18 at a particular height above the frame 2. The angle of the seat on the seat support rod 19 relative to the frame 2 may be adjusted to suit the user, for example by operating a series of levers on the underside of the seat (not shown) . The seat 18 may be one of a range of possible seats each adapted to be fitted to the upper portion of the seat support rod 19. In this way, a seat can be selected which suits the user of the transport means 1.

The seat may fold against the frame in the direction indicated by arrow 21 , the seat support rod pivoting about a connection with slide 20. However, in a more preferred embodiment, the seat support rod 19 and the seat are easily detachable from the frame 2 and can be stored separately whilst the transport means is in storage.

In use, the user sets the height of the cross bar 13, and the height of the seat 18, and adjusts the position of the slide member 20 on the frame to suit his/her requirements. If the user is an invalid, the seat may be selected from a range of different seat shapes to ensure that the seat offers the most support and comfort for the user.

The tubing of the frame 2, the wheel mounting means 4, the seat support means 19, the rod 12 and the cross bar 13 is preferably hollow and extruded of aluminium, although any suitable material could be used. The tubing in transverse cross section is elliptical in shape to improve its strength. This choice of materials and construction helps to keep the weight of the transport means 1 to a minimum without compromising strength.

The user, in one embodiment, rests his/her weight on the seat, and grasps the handle grips 14. One hand can operate the joystick to power the front wheels and drive the transport means forwards or backwards. If the user wishes to make a turn in one direction, say for example to the right, the user moves the joystick 16 towards the right which, in turn, reduces or cuts power to the right hand wheel. Ideally, the right hand wheel stops and is then powered in reverse. The power to the left hand wheel remains constant, or increases in the forwards direction to effect the right hand turn. The transport means 1 can rotate about its rear castor 3.

In a second preferred embodiment, the user rests part of his/her weight on the seat, and uses one or both trailing legs to support the rest of his/her weight on the ground. The transport means can be powered by moving the joystick in a forwards direction to power the front wheels, whilst manual assistance can be provided from the trailing legs to push the transport means along. Alternatively, the transport means could be powered entirely by the trailing legs. The single rear castor, and the absence of a rear axle or protrusions from the sides of the frame 2 ensure that the trailing legs are not impeded. The second preferred embodiment is especially applicable to those patients who still have the use of one or both legs, or who wish to build up the strength in their leg after an operation or other medical treatment.

In the embodiment shown in Figure 2, transport means 25 is provided with a seat post 26, fixed to a rear portion of an elongate frame member 27. The elongate frame member is bifurcate towards its rearward portion, one part of the member extending upwardly to receive the seat post and a second part extending rearwardly. A rotatable member 28 is mounted rearwardly of the seat post 26. The seat post 26 can be telescoped in order to adjust the height of the seat relative to the elongate frame member. The seat post is easily removable from the elongate frame member 27.

The rotatable member 28 comprises a castor wheel. This castor wheel is fixed and independently driven by a motor (not shown) . Its horizontal position is adjustable in relation to the elongate member, for example by clamp means or by pivoting.

A shock absorber 29 is located between the castor wheel 28 and its mounting 30 on the elongate frame members 27. This increases the user's comfort and the stability of the transport means on uneven surfaces.

A seat 31 is removably mounted on top of the seat post 26. It may be pivotally mounted or adjustable horizontally or vertically, for example by means of clamping devices. The seat is custom-made for each user. The user is thus securely held and supported on the transport means. Additional support for the user may be provided by means of a front support 32 which may extend from the front part of the elongate frame member 27 or, as illustrated in Figure 2, from elongate rod 33 which supports the handlebars 34. A pad 35, secured to the front support, is contoured to the user's shape.

Further parts may be fitted to the transport means to support the user. These are shown in Figure 3. A removable stump support 31 A may extend from the seat post 26 or, as illustrated in Figure 3, from the elongate frame member. The stump support is also contoured to fit the user. Running boards 37, one for each foot, are removably mounted, for example by clips, to the twin portions of the elongate frame member. The running boards can be clipped together for extra security. They enable the user to sit back on the seat and to rest his/her feet, if he/she is tired.

Forearm or elbow supports 38 may also be provided on the front handlebars. These comprise shaped pads which may be contoured to fit the user and adjustably secured to the handlebars. A handgrip 39, for use with the supports, links the two supports.

Figures 3 and 4 illustrate the front portion of the transport means of Figure 2. Handlebars 40 and 41 are formed from two hollow aluminium extrusions and are supported on the front portion of the elongate frame member. This front portion comprises a platform 42, constructed from a metal or plastics tray riveted to the frame, which supports a battery 43, together with an electronics control unit 44 and wheel motors 46, 47 (shown in Figure 9) . The handlebars 40 and 41 do not act to steer front wheels 48, 49; the front wheels 48 and 49 are fixedly mounted in relation to the frame and steering is accomplished by means of differential circumferential driving of each wheel.

A plastics moulding 50, which may be highly decorative and/or brightly coloured or fluorescent, is mounted on the front of the handlebars. This moulding may act as a safety device and/or may be used to support lights and warning devices such as klaxons.

The seat post 26 and the handlebars 40 and 41 are both pivotally mounted on the elongate frame member 27. In order to conveniently transport the mobility aid, the handlebars 40 can be pivoted towards the back of the frame member 27 and the seat post 26 pivoted towards the front of the frame member 27. The mobility aid may then be easily lifted and transported, for example inside the boot of a car. A winch attachment (not shown) can be provided to enable the device to be lifted into a car boot. Even if the user is frail and/or without assistance the device can still be transported.

Figures 5 and 6 show the typical proportions of the mobility aid in relation to a user 51. In this example the user is 1.7 m tall. As shown in Figure 6, the proportions of the device relative to the user should be such that the user is able to propel the vehicle along the ground when sitting on the seat.

In Figure 7, an alternative embodiment of the second rotatable member is shown generally at 52. This embodiment comprises a castor wheel and can pivot with respect to the frame member. A plastics wheel 53 is mounted on an axle 54 which is supported in an external frame 55 and connected, via a shock absorber 56, to a shaft 57 engaging the frame member. The wheel 53 is shaped so that it contacts the ground by at least two points, spaced apart orthogonally with respect to the length of the elongate frame member. This increases the sideways stability of the mobility aid. The dual points of contact also reduce "castor clatter" . Alternatively, the same effect can be achieved by means of duplex wheels which rotate together. These are considered to comprise a single rotatable member in accordance with the present invention.

Figure 8 shows schematically an alternative embodiment of the seat post 26 and seat 31. These are pivotally mounted with respect to each other and the frame such that several positions of the seat post 26 and seat 31, for example those indicated at (a) , (b), and (c), are possible. For example spring members located on the seat post may engage suitably- positioned holes in the elongate frame member 27.

In position (a) the post and seat are folded against the elongate frame member, so that the mobility aid may be easily transported. In position (b) or "scooter mode" , the user's weight is directed on to the front portion of the mobility aid and the resulting lower position of the seat means that the user's legs may more easily be used to propel the vehicle. The forward position of the user's centre of gravity enhances the stability of the vehicle. In position (c) the user is in an upright "sitting" position and can, if required, rest his/her feet on the running boards, relying on the driven power of the vehicle. The centre of gravity of the vehicle is then largely on the rear portion of the vehicle. The increase in weight may act to pivot the castor wheel mechanism so that its point of contact with the ground is moved rearward to enhance stability. This comprises "sitting mode" .

Figure 9 shows schematically an electronic control system for the embodiment shown in Figure 2. Three motors, 46, 47 and 58, drive the front wheels and rear wheel respectively. These are powered by a 12v battery 43. This battery 43 is preferably lightweight but still able to provide adequate power for at least 5 miles. The electronic control system is contained in a box 44. It is microprocessor-control based. It receives input from switches 59, which are mounted on the end of the handlebars so that they may be easily controlled by the user's thumbs. It also receives input from a proportional joystick 60. The switches or joystick may each respectively alone control the system or they may both do so. They may be interchangeable so that the control system can receive input from either.

The control system may be set up for individual users in order to maximise their control of the mobility aid. For example, either the joystick or the switches may be used to control speed; the joystick may be used for directional control and the switches for acceleration, or vice versa. The software is sufficiently adaptive to allow this. Furthermore, the action of the joystick can be suitably damped, e.g. by electronic or software means, so that it is suitable for use by a person suffering with tremor. The version of the software shown in Appendix A (below) enables a user suffering with moderate to severe tremor to control the mobility aid effectively.

The software has four setup screens. Clicking on the MAIN tab brings up a joystick simulation screen. The joystick simulation screen shown in Appendix A comprises a simulator control (shown as a circle) . A cursor in the circle represents the relative position of the joystick in the forward, back, left and right directions. This position sets the power, speed and other motor settings as displayed on the charts headed "LEFT" and "RIGHT", for the left and right motor respectively. The path that the mobility aid will take as a result of the changes in these settings is displayed in the right hand box.

Clicking on the GRAPH tab brings up the motor speed characteristic setup, shown at the bottom of page 1 of Appendix A. The graph on the right hand side of the screen indicates the magnitude of the motor power settings at different steering angles. The "left" and "right" controls control the power of their respective motors. The user can control the numbers entered into the "left" and "right" and "angle" boxes to change the sensitivity of the steering at different angles. For example, the graph shown in Appendix A indicates that both motors are idle (with respect to each other) in the straight ahead (90°) direction and the flat gradient of the line means that the steering is relatively insensitive around this point. Tremor is thereby compensated for in this position - a positive movement of the joystick must be made to steer the mobility aid.

The COMMS and SETUP screens shown in Appendix A assist downloading and enable the user to set the parameters shown.

Once the user is satisfied with the settings they can be downloaded into the microprocessor-based controller. The acceleration of the motor can be controlled separately.

A mobility aid according to the present invention thus provides a complete mobility solution for users having a wide variety of impairments. It promotes and improves leg functioning and increases physical fitness, while enabling the user to rest when tired. It may be used indoors or outdoors, and is easily transportable. Its steering system ensures a high degree of manoeuvrability whilst stability is maintained or even enhanced. Many adaptations, variations and improvements will be apparent from the disclosure contained herein which fulfil the aims of and are encompassed by the present invention.

Claims

1. Transport means comprising: (a) an elongate frame member having front and rear portions relative to the predominant direction of motion of the transport means; (b) a pair of first rotatable support members operatively associated with said front portion; (c) a single second rotatable support member operatively associated with said rear portion; and (d) steering means adapted in use to change the direction of motion of the transport means.

2. Transport means according to Claim 1 , in which the first rotatable support members (b) comprise wheels.

3. Transport means according to either preceding claim, in which each of the rotatable support members (b) and (c) is adapted to be powered.

4. Transport means according to any Claim 3, in which each of the rotatable support members (b) and (c) is adapted to be independently driven.

5. Transport means according to any preceding claim, in which the second rotatable support member (c) comprises a wheeled castor.

6. Transport means according to any one of Claims 1 to 4, in which the second rotatable support member (c) is fixed in position in relation to the elongate frame member (a) .

7. Transport means according to any preceding claim, in which the second rotatable member (c) is adapted to be powered.

8. Transport means according to any preceding claim, further comprising a seat which is capable of adjustment of its height and position relative to the elongate frame member (a) .

9. Transport means according to any preceding claim, in which the steering means (d) comprises an elongate rod adapted to be rotated around its longitudinal axis.

10. Transport means according to Claim 9, in which the length of the rod is variable.

11. Transport means according to any preceding claim, in which the steering means (d) is provided with powered movement.

12. Transport means according to Claim 11 , in which only the pair of first rotatable support members (b) is powered.

13. Transport means according to any preceding claim, which is adapted, in use, to be propelled by the legs of a user.

14. Transport means according to Claim 11 or 12, in which the powered movement is actuated by manually-operable switching means.

15. Transport means according to Claim 14, in which each member of the pair of first rotatable support members (b) is independently driven and the switching means varies the power supply to vary the rotational speed of each of the first rotatable support members (b) , thereby effecting a desired steering direction.

16. Transport means according to any preceding claim, in which the elongate frame member (a) is made of a metal.

17. Transport means according to any preceding claim, in which the elongate frame member (a) is of hollow, generally tubular construction.

18. Transport means according to any preceding claim, in which the elongate frame member (a) is foldable for storage or transport.

19. Transport means according to any preceding claim, in which housings are provided on the elongate frame member (a) to receive one or more batteries, and/or electronic components and associated circuitry.

20. Transport means according to any preceding claim, further comprising seat support means, moveable relative to the elongate frame member (a) to a plurality of possible positions.

21. Transport means according to any preceding claim, further comprising a gear train to transmit motive power to the front wheels.

22. Transport means comprising:

(a) an elongate frame member having front and rear portions;

(b) a first rotatable support member operatively associated with said front portion; (c) a second rotatable support member operatively associated with said rear portion; and

(d) support means for a user, said support means being capable of adjustment from a first position wherein the centre of gravity of the transport means in use is substantially operatively associated with the front position of the frame member (a) to a second position wherein the centre of gravity of the transport means is substantially operatively associated with the rear portion of the frame member (a) .

23. A program on a carrier, the program being adapted to effect control of transport means according to any preceding claim.