NZ615260B2 - Step-climbing attachment for a wheeled chair - Google Patents

Abstract

step-climbing attachment for a wheeled chair, the attachment including a wheel-mounting chassis for mounting wheels, a first and a second wheel each mounted on the wheel-mounting chassis for rotation about their axes, the first and second wheels are each adapted to move relative to the other, the relative movement in use being between a ground engaging position and a step-engaging position so that in use at least one of the first or second wheels engages a step, and respective link arms 128 connected to the chassis so as to mount the first wheel and the second wheel to the chassis and allow each wheel to swing from the ground engaging position to the step-engaging position. At least one of the wheels has a hub 135 and a motor 190 and gearbox mounted within the hub. The motor and gearbox are connected to the respective link arms 128 so as to pivot the other of the first or second wheels into a step engaging position. relative movement in use being between a ground engaging position and a step-engaging position so that in use at least one of the first or second wheels engages a step, and respective link arms 128 connected to the chassis so as to mount the first wheel and the second wheel to the chassis and allow each wheel to swing from the ground engaging position to the step-engaging position. At least one of the wheels has a hub 135 and a motor 190 and gearbox mounted within the hub. The motor and gearbox are connected to the respective link arms 128 so as to pivot the other of the first or second wheels into a step engaging position.

Description

STEP-CLIMBING ATTACHMENT FOR A WHEELED CHAIR Field 9! the Immm The present invention relates generally to step climbing attachments suitable for use in a range of movable items such as for example trolleys. walkers. wheelbarrws. chairs. scooters and the like. In selected embodiments. the invention relates to wheeled chairs including hairs to afford increased accessbility for infirm people and less able people.

Emma . movable baskets and trolleys. walkers. rs and the like are useful for carrying and moving items such as luggage. groceries. heavy items. as well as people. Some of these items may be motorised. but many ns of these devices have imitations when negotiating stairs. Some wheeled attachments are also known but e cumbersome. large and inflexible apparatus.

Wheelchairs in ular can be very difficult to operate over uneven ground. kerbs. gutters, and. most difficult of all: staircases. This is so It the wheelchair is a manually-pushed chair but particularly so for a powered chair which uses electrical power for propulsion and steering. These latter types of chair. due to the propulsion and onboard energy storage systems are heavy and large, and known models are not easy to drive over uneven ground, and particularly. as mentioned. staircases.

The present Invention provides Improved step climbing attachments le for use with Wheeled chairs and other vehicles such as wheelchairs.

Throughout this specification and the claims that follow. the ing s are given the meanings that a person of ordinary skill in the art would apply to them as well as the clarifications set out below.

Gromd engaging position: a support position adopted by an element of an apparatus described herein wherein the element abuts a portion of open ground. , usually from above to rest on the open ground to support at least some of the mass of a movable item. such as for example a chair.

Step engaging position: a position adopted by an t of the apparatus described herein wherein the eiernent abuts or engages a tread portion of a step so as to t at least some of the mass of a moving item, such as for example a chair. me i According to one aspect of the present invention there is provided a step cll'nbing attachment suitable for facilitating the negotiation of irregular patl-nuays. road and open ground and suitable for use with a wheeled chair, the step climbing attachment including: ' a chassis adapted to mount to a base region of the wheeled chair; at least a first and a second ground engaging unit iveiy mounwd to the chassis, at least one of the first and second ground engaging units adapted to move relative to the other of the first or second ground engaging units and the chassis. the relative mOVement be'ng between a ground engaging position and a ngaging on. ' There are optionally provided several different alternativearrangements. including wholly passive ements. where the support assemblies are pushed into step engagement positions by the momentum of. for example, chair to which it Is attached. to assive arrangements, where the support assembly Is not self— propsllsd but motors elevate the ground engaging units into a step engaging position, to fully powered arrangements where both ambuletion and stepping is accomplished by motors. Other combinations are also le, such as ropelled but passive stepping arrangements- assive arrangements (Castor Wheels) The ground engaging units may be arranged in any suitable way including where the ground engaging units include one or more posts. sleds. skids and/orwheei assemblies. In a preferred embodiment. the first and second groUnd engaging unils are wheel assemblies and each includes ground engaging caster wheels. in one example embodiment the ground engaging mstor wheels include a hub for rotating a main castor wheel body thereabout. The hub may include any suitable arrangement. including a typical central rotating axis or a rotating eral or circumferential hub. wherein a peripherd or annular tyre or outer wheel assembly is mounted on a bearing _ receandrotatesaboutadiscwheei body.

The chassis itself may have an Integral ground engaging portion. Optionally, however. the chassis includes a mounting assembly to mount the first and second ground engaging units to the chassis so that one or more of the ground engaging units can engage the ground rather than the chassis itself. Movement of the mounting assembly to move the ground engaging units may be a vertical, horizontal. extension. rotating about a yaw axis. or plvoting movement about a horizontal axis or a ation of one or more of those movements. in a preferred embodiment the mounting assembly includes a pivoting element so that the ground engaging units and/or chassis in use are rotated orswung about a 1O horizontal axis and in so doing the ground ng units are swung n the ground engaging support position and the step-engaging support on.

Optionally the plvoting element includes at teem one link arm which extends n a chassis and mouthed to a chassis mounting point; and a wheel and mounted to a wheel or ground engaging unit mounting point: Optionally the wheel end of the link arm is mtatabiy mounted to the wheel or ground engaging unit to bly mount the link arm to the wheel or ground engaging unit.

The wheel and of the or each link arm is ally eccentricaliy mounted to the ground engaging unit, however. it may be momted to the centre of the ground engaging unit lithe latter has a centre, such as for example when the ground engaging unit is in the form of a wheel. The s and may be mounted to the chassis at a position efromthewh‘eel’scentreofrotation. and is optionallycutslde the circumference of the wheel. ferred embodimentthelinkanhsareinthefonnoflinkageesothatthe wheel may be moved and controlled by being mounted at one of the nnkage joints. in one embodiment the centre of rotation of the wheel can be moved outside the wheel itself. Optbnally. a first linkage is in the form of a four bar linkage wherein first and second links are liy mounted at spaced-apart locations on the chassis. the first link being disposed lower than the second unit. A third link is in the term of one ofthe wheels, and the fourth link is formed by the chassis . in typical four—bar link fashion. Optionally the first link is shorter than the second link so as not to jam when in Operation. Optionally the second link includes a spring andlor damper arrangement to provide a suspended chassis.

Optionally a motor and gearbox is mounted within the wheel for pivoting of the ground engaging units into a step engaging position.

Thewhe'el huboptionally connecteto adistalendoftnefirstitnk. Optionally a gearbox outlet is disposed at this connection.

A motor plate is optionally provided and optionally mounts to a distal end-of the second link. The motor plate s over the tread ofthe wheel rim and tyre and mounts to an outboard side of the wheel at its centre.

Optionally one or other of the ground engaging units is disposed In use on the chassis in a position relatively forward of the other ground engaging units so as to facilitate step climbing or descending.

Optionally one or more motors are provided to rotate the links or linkages so that the ground ng units can be quickly and tely positiomd above or on the step tread. Optionally the motor and links and linkages are adapted to be strong enough to Iitt or lower its tion of the mass of the chair when in use. The link arm may be integral with a disc main wheel body.

Optionally the s is disposed between two wheels.

Optionally the s Includes a swivel mount so that the chassis may swivel about a yaw axis. either passively or actively under control of a control system and motor to be turned or steered In response to operator input. Optionally the swivel mount is in use ed forward of the link arm pivot mounts for increased stability under forward motion.

Optionallythe first and second ground engaging unite orwheels, and chassis are independently relatively movable and operable. Optionally this ndent ion ls under power of separate drive motors. ropelled limbing Arrangements- In one arrangement, the first ground engaging unit a powered wheel .26 assembly in that It can provide propulsion to a chair or trolley. In that arrangement, though it could be employed in other non-powered arrangements. the second ground engaging unitis lnthet’orrnofa planetalywheel assemblywhich is mounbd so asto orbit the first powered wheel assembly. An idler wheel ls optionally provided and is disposed to be in contactwith thetread ofthe powered wheel assembly, and in operation is in contact with the first and second wheels for additional support and to change the direction of rotation ot the second planet wheel or ground engaging unit.

Optionally one or more brackets are provided to support the planet wheel radially outwardly mlative to the first powered wheel. A proximal end of the or each bracket is in this embodiment engageable to the hub assembly or chassis assembly thattheplanetwheeimtatesatashnlarmtafionalspwdtotheflratpoweredmeel.

Optionally the second wheel ly moves Into the ngaging position relatively higher or lower than the ground engaging position. in some red ments the same bracket or a further provided different bracket supportthe idler wheel at Its radially outward disposition relative to the front powered wheel.

In operation the planetary wheel may itself run on the ground and be pomred by the first powered wheel, through the idler Wheel.

Optionally there are ed two planetary wheels -— one disposed generally at the front and one disposed lly at the rear of the powered wheel.

Another arrangement for a self propelled stair cimbing wheel optionally uses the wheelchair drive motor for propulsion and climbing so that a separate dedicated motor is not required forstair ng. A belt may be used. stretched batman a large and small puley, or the other arrangement abovedescribed could be used. in an alternative arrangement. the gearbox provided may be a variation of a standard two stage planetary gearbox. Thus. a first stage includes a frat gear forming the sun gear. second gears forming the planetary gears. and an outer ring ton-hing an annular gear. A spider is provided which also acts as the sun gear for a second stage.

. A third set of gears disposed adjacent the first stage may be provided which are ln‘the form of planet gears and a solid ring acts as an r gear of the second stage and is fixed to a frame of the wheeled chair. A wheel arm may be provided which tonne the spider forthe second stage and is the output of the gearbox. A tyre may be ted to the annular gear of the first stage so that it forms the driven or propelled ' wheel. _- .

When the geared arrangement descrim above is in operation. the first stage annular gear is feed to the wheeled chair. for example, using a brake. and under power, thewheel armthen rotateewith respectto an inputshattwltha ratio of between 4:1 and 12:1: the tyre will beflxed in position.

For g or propulsion mode. the first stage annular gear (and tyre) are released and the first stage spider is fixed instead, the Wheel arm remains fixed and the annular gear and tyre rotate with a ratlo'ol -1 :1 which is a substantially similar speed but in an opposite direction.

In this geared embodiment the gear arrangement s the same result as using two clutches and two brakes to e and engage the wheel arm and tyre but only requires two . in one of the Castor Wheel, Power Wheel, or Manual Wheel arrangements or one ofthe PoweredWheelArrangements for a ManualWheel. the aide eta wheel can be operativeiy mounted to. or can be integral with the chassis of the support attachment.

In another embodiment there is provided a step dimbing arrangement tor a powered or even unpowered wheel which Includes a rotating chassis wiich includes . two spaced-apart pulleys and between which is mounted a track extending in an endless loop between the two -apart pulleys. One of the pulleys includes the geared arrangement as described above and the other pulley is smaller than the other otthe pulleys. Thetrackin usepropelethe chairalongtheground andwhensstep is encountered. the chassis is rotated so as to elevate the small pulley, and the track s the chair up the steps. the track simply allowing the chair to propel Itself up an incline rather than flat tenaln. The track is in some optional embodiments a rubber loop or tyre.

~ The geared arrangement described above and the d'riferential may be incorporated so as to facilitate climbing up the stairs. since it selects a lower gear. in accordance with an alternative arrangement of the present hvention there is provided a step climbing attachment for a d chair. the step climbing arrangement including a chassis. a first pulley. and a second pulley spaced from the first pulley, and a track extending between the pulleys. n the chassis is rotatable so that in use the track can be inclined for the dish to ascend a staircase.

In accordance with another aspect otthe present invention there is provided a wneeed chair suitable for negotiating tnagular'ground including stairs. the d chair including at least one step ng attachment. the step climbing attachment ing: a chassis adapted to mount to a base region of the wheeled chair; at least a first and a second ground engaging unit operatively mounted to the chassis. at leastone of the first and second ground engaging mite adapted to move relative to the other of the first or second ground ng unite and the chassis. the relative movement being between a ground engaging on and a step-engaging position.

In accordance with yet another aspect of the present invention there is ed a control system for lling a step climbing unit attached to a wheeled chair and including a chassis and a first and a second ground engaging assembly mounted to the chassis, the control system being configured to: move the first ground snowing ly together with or separately from the ascend ground ng ly. the movement being relative to one another orthe chassis. the nt further being such that the first orthe second ground engaging assembly moves between a ground engaging position and a step-engaging position; the control system further being configured to exbnd, lift or lower the ground support s through a 1O height equal to a height or drop of the step.

In accordance with still another aspect of the present invention there is provided a medrod of negotiating a step with a wheeled chair, the method ing the steps ct mounting a first ground engaging assembly and a second ground engaging assembly to a t chassis; moving at least the first ground engaging assembly relative to the support diesels andlor second ground engaging assembly between a ground engaging on and a step-engaging position; extending. lifting or ng the support chassis through a height equal to height or depth at the step.

In accordance with a yet further aspect of the present Invention. there is ed a computer m product for configuring a control system to control a step climbing attachment unit ed to a d chair, the computer program product configuring the control system to negotiate a amp by: causing the movement of a first ground engaging assembly or a second ground engaging assembly; the movement being relative to the other ground engaging assembly or a chassis to which the first and second ground engaging assembly are directly or indirectly attached. the movement further being such thstthe first orthe second ground engaging assembly move beMen a ground engaging position and a step-engaging position: and extending. lifting or lowering the ground support chassis through a height equal to a height or drop of the step; Awarding to a yet further aspect of the present Invention there is provided a kit of parts for modifying a wheeled chair to negotiate steps and irregular ground. the kit at parts including a step climbing attachment suitable forfacilltatlng the negotiation of irregular pattwvays, road and open ground and suitable for use with a wheeled chair. , the step climbing attachment comprising: a chassis adapted to mountto a base region of the wheeled chair. the chassis further adamd fOr operatively mounting one or more ground engaging units; at least a first and a second ground engaging unit operatively mounted to the chassis. at least one of the first and second ground engaging units adapted to move relative to the other of the first or second ground engaging units and the chassis. the relatIVe movement being between a ground er-rgaging on and a step-engaging position.

According to a still further aspect of the present invention there is provided a method of modifying a manual hair or a one. two. three. four or more wheel drive self-propelled wheelchair or r so that it ates undulating or uneven ground or steps. the method including providing a step clmblng attachment suitable for tating the negotiation of irregular pathways. road and open ground and suitable for use with a wheeled chair. the step climbing attachment including: a chassis adapted to mount to a base region of the wheeled chair. at least a first and a second ground engaging unit operatively mounted to the chassis. at least one of the first and second ground engaging units adapted to move relative to the other of the first or second ground engaging units and the chassis. the ve movement being batman a ground engaging position and a step-engaging position: and connecting the step climbing attachment to the wheeled chair.

Optionally the control system controls the relative movement of the first and second ground ng units. Optionally the control system includes hardware and software ecture such as a processor. memory means. storage means. input/output devices and like le peripherals.

Optionally the control aysbm ls adapted to receive inputs from suitable input units. in response to Which the control system may make selected adjuetments to the 26 relative nt of the first and second ground engaging units.

Optionally the Input units include step-detectors or detectors for detecting variations in ground surface level. such as lasers. . light beams. ultrasound units. or the like. Further optional inputs include receivers to receive inputs from radio- transmitters or other networks such as the intemet or other control signals.

Furthermore. optimal electronics, modules and/or input units may be provided so as to provide position control information mgarcling the chassis height. «Miser or skid rotation or movement or extension to the processor. These units may Include. for example. r units. ucer units. either linear or rotational. and the like.

Optionally the circuits are powered drcuits with a voltage of 24V DC. however it will be appreciated that other voltages would be suitable. Optionally compact and electrically commutated electric motors are provided to power the red eccentric and independent rotation of each “meet. Optionally a motor driver is ed to provide an independent speed and direction control for each motor. The motor driver also allows motor als to be shorted to increase locking ability when not in use. ally a microcontrolier decodes the encoder output and provides speed and direction signals to the motor driver and communicates with the wheelchair l system for the self-propelled wheelchair.

Optionally the motors are of a form which the into a space envelope provided by the caster wheel. Optionally these motors include compact gearboxes such as hannonlc drives and/or gearboxes and integral encoders.

Optionally slip rings are included for power lines to allow continuous rotation of the caster wl'reet Optionally the control apparatus or mechanism or electronic system . 16 also controls the attitude and height of the chassis and support unit. This control codd be achieved by either driving the caster axles directly or providing a second joint over the wheel contact point.

In one arrangement. a passive mechanism may be included which Is not d but which may use a spring or other device to use momentum associated with pushing a chair or trolley, and the impact ated with t with a step to move the first and/or second ground engaging units or wheels and ultimately the chassis into a step engaging position. either simultaneously or consecutively.

Throughout this specification. unless the context requires otherwise. the word ise". or variations such as ”comprises" or "comprising". will be understood to imply the inclusion of a stated element, Integer or step, or group of elements. integers or steps. but not the exclusion of any other t, integer or step. or group of elements. integers or steps. - Any discussion of documents, acts. materials. devices. articles or the lflte which ~hasbeenincludedinthepreeentspecilicaticnlssoieiytorthepurposeoiprovidinga context for the present Invention. It Is not to be taken as an admission that any or all of these matters form part of the prior on base or were common general knowledge in the field relevant to the present invention before the ty date of each claim of this . specification.

In order that the present invention maybe more clearly understood. eitample embodiments will be described with reference to the following drawings. n the s Figure 1 is an ric view of a step climbing attachment for use with a d chair or other d or moving item. the step ng attachment disposed on a flat surface in accordance with a fist embodiment of the present invention; Figure 2 is an isometric view of a step climbing mechanism showing a ground engaging tyre or belt. the mechanism disposed on a flat surface, the mechanism in accordance with a second ment of the present invention: Figure 3 is an isometricviewofameled chairwhich is in accordmcewith an embodiment of the present invention. the d chair being adapted to receive the first and second embodiments of the present invention shown in Figures 1 and 2; Figure 4 is an Isometric view of a portion of the geared mechanism shown in Figure 2; Figure 5 is an isometric view of a step climbing attachment according to a third - embodiment of the present invention. the step climbing attachment being disposed at a base of a step: Figure 6 is an isometric view of the step ng attachment of Figure 5 disposed in a position having a first wheel elevated and ready for extension Into a step engaging position. and a chassis being elevated above a second wheel; Figure 7 Is an isometric view of the step cfimblng attachment of Figure 5, the. first wheel in a step engaging position; Figure 8 is an isometric view of the step climbing attachment of Figure 5, the second wheel being drawn up offthe ground and readyto be drawn into astep ensnrrins position; Figure 9 Is an isometric view of the step climbing attachment of Figure 5. both wheels engaging the step: Figure 10 is an isometric view of a step climbing ment in accordance with another embodiment of the t invention: Figure 11 is a plan View of the step climbing attachment of Figure 10; Figure 12 is an isometricview ofa step climbing attachment in accordance with another embodiment of the present invention: - Figure 13 shows the embodiment of Figure 12 in a step engaging posflion; Figure 14 shows the embodiment shown in Figure 13 in a side elevation view.

‘ Flgure15isan isometrioviewoftheembodimentofths presentinvention shovm in Figures 12 -14with some items removed forclarity; Flgure16isatiowdiagramofanexsmplemethodofstepciimbingwithan ment of the present invention; Figure 17 Is a schematic view of control system architecture for implementing example step ng s used with embodiments of the t ion; Figure 18 Is another schematic View of control system components; and Figure 19 is a schematic of control system components; i n a th lnvsn e or Idie Castor Wheel Arrangement Referring to Figures 5 to 9 there IS‘ShOWI'i a step climbing ment generally indicated at 10. the step climbing attachment 10 suitable for attachment to a wheeled chair orwheeichair (Figure 3) or other wheeled or e item such as a scooter. trolley orthe like. The step climbing attachment includes a chassis 12 for mounting a first ground engaging unit 14 and second ground engaging unit 16. The first and second ground engaging units 14. 16. are in the form of castor wheel assemblies 16. 17. however. they could be in the form of skids. sleds, posts or the like.

The caster wheel assemblies 15. 17 include hubs 18. 19 for passive rotation of a main caster wheel body 20. 22 thereabouts. The hubs 18. 19 include a central axle assembly 24. 25. Connected to the hub is a link arm 26. 27. extending en a chassis end 28 and wheel axle end 29‘ The link arm 26. 27 is rotatably connected with bearings atboth Its endstoailwrotation ofan eiementtowhioh itisconnected.

The chassis and 28 ofthe link arm is mounted to the chassis at a position remote from the wheel axle end 29. the latter orwhloh is disposed at the wheel's central axis.

The points of rotation forthe chassis and of the link Inns 26. 27 are remote irornihecentre ol’rotationofthewheel 20, 22 and are as shown iguree. wherein the rotation porn 30 for the first ground engaging main Mteel body 20 is d of the rotation point 31 for the second ground engaging main wheel body 21 so as to provide sddltional reach for the attachment 10. ssis12lnc|udesamountingpoint32intheformofapivoteubaxle33 sothattheattechmentmaypesslvelyrotateeboutayawaide, abouttheaide33. An alternative arrangement hcludes steering or powered yaw rotation control for the axis Passively ng main link aims is contemplated as an . However, in . the preferred embodiment shown, motors 35 and gearboxes 34 are provided in order to rotetethe link arms 26. 27. The motors 35 may be hydraulic or, as is preferred, they 1O are electric. and disposed fore and sit in use.

A connection or mechanism is contemplated as an option to join the motion of the link arms 26. 27. However. in the preferred embodiment shown, the link arms 26, 27 in use are independently controlled and moved.

A control system (not shown) is provided to control the Independent motion of the two link arms 26. 27. The control system moves the enns either automatically, in response to inputs from sensors. encoders 90 or manually by other Input devices such as control Joysticks. The control sysbm includes a software product which operates the link arms according to a method hereindescribed.

In the dlffsmnt embodiments shown in the Figures. like numerals denote like parts. For example, 10. 110 and 210 show dlfierent embodiments of the same conceptual wheeled attachment. and so on.

One difference between the concepts shown in Figures 5 -'9 and 12 - 15, is that the one in Figures 12 — 15 includes ng circumferential tyres 40, 42 on a stationary hub 118. 119. This tends to reduce the annular thickness of the main wheel body 120 required.

Another difference between the embodiments bed in Figures 6 — 9 and Figures 1 and s 12 - 15 is thatthe Inks are in the form of four-bar linkages. and the motors 135 are d on the wheels 120. The first link, 126, is in the form of a short arm and is connected y to plate 125A. The second link 127 is plvotally connected to the top of the chassis spaced from the first link 126. The second link is also pivotelly connected to the third link. 128, and the third link may also be considered the wheel hub. so that the motor 135 and link 128 are rigidly connected together. The chassis may be considered the fourth link as in all four bar mechanisms.

The second link 127 also Includes a suspension device. including a spring and damper 129.

Self-propelled Wheel Arrangement The arrangement shown in Figures 9. 10 and 11 Includes a first ground engaging unit 214 in the fonn'or ropelled or powered main wheel body 220, and a second ground engaging unit 216 in the form of a secondarywheel 222 which is mounted on a ary drive arrangement 280. The planetary drive arrangement 280 includes a support bracket 282 upon which is mounted an idler wheel 284 and the secondary wheel 222.

In some arrangements the planetary drive arrangement 280 may include a locking ism (not shown) whichcan be selectively locked to the rotation of the main wheel body 220 to passively lift the main wheel body 220 up Into a cup engaging position to engage one or more steps. The locking mechanism may include a friction device. a cog, dog arrangement, chain and sprocket or like means. ' In other anangemants the rotation of the ary drive arrangement may be powered by a dedicated actuator. to provide a drive force n the bracket and chassis. or bracket 282 and main wheel body 220.

A differential gear system may be provided so that when the main wheel body 220 Is In a ground engaging position and is being powered along the ground unobstructed. the ditlerential gear system transfers power to the drive wheel. When in usetl'iemelnpcweredwheelmis ctedbyoneormoresteps.thediflerentiei gears transfer power to the support bracket 282 so that the ary wheel 222 is moved to a step-engaging positIOn and then lifts the main wheel body 220 up the step and into its own step-engaging position.

The planetary drive arrangement may also include s. dampers and other mechanisms to facilitate climbing and lowering, up and down steps respectively; The secondary wheel 22 may be used as a ground ng wheel upon which to drive a wheelchair along the ground in an elevated position.

Other Castor Wheel Arrangements The four-bar ism advantageously provides upright orientation of the wheels during extension and a greater lifting strength.

The wheel hub optionally connects to a distal end of the first link. A gearbox outlet is disposed at this connectlon.

Another embodiment of the powered step ng wheel is shoWn in Figure 2.

The gearbox provided in this embodiment is a variation of a standard two stage . planetary gearbox A first stage includes a first gear forming the sun gear. second gears forming the planets, and an outer ring forming an r gear. In this arrangement a spider is provided which also acts as the sun gear for a second stage.

A third set of gears disposed adjacent the first stage are provided which are in the form of'planet gears and a solid ring acts as an annular gearof the second stage and is fixed to the wheelchair frame. A wheel arm is proVided which forms the spider for the second stage and isthe outputolthe gearbox. Thetyre will emdtolhe annular gear of the first stage.

The first stage annular gear is fixed to the wheelchair (using a brake) and the wheat arm then rotates with respectto the input with a ratio of between 4:1 arid 12:1 and the tyre will be fixed. When the first stage annular gear (and tyre) are rebased and the first stage spider is fixed instead then the wheel arm will remain fixed and the annular gear and tyre will rotate with a ratio of -1:1 (same speed but opposite direction). Which means that the.wheelchair will drive at the same speed as normal.

This gear arrangement is advantageous In that the same result can be achieved as using two clutches and two brakes to isolate and engage the wheel arm and tyre but only requires Mo brakes. in operafiomtheembodimem ofFigure 1. FiQLI’eS5-9 and 12-1 5 actasset out below. The attachment 10 negotiates steps as follows: Figure 1 shows the attachment to ching or abutting a step 5. The first and second ground engaging wheel lies are disposed side by side.

Then, as shown in Figure 6, the attachment 1o responds to an input from an or or other sensor or controlbr to move the attachment into a step-engaging position by ng both the link arms 26, 27 (or linkages) under power. Movement of a second wheel arm elevates the chassis 12 and movement of the first wheel assembly 15 places the first wheel onto a step tread 6. It is of course possible that only one link arm needs to rotate to place the wheel 20 onto the tread or into the step- (or tread-) engaging position, but it will depend on the height of the riser 7.

ThenextstepisshowninFigure?inthatitisshownthatflteilnkannZ'lisina al position. which causes the chassis 12 to be elevated to its highest possible relative position, and the other Iinkarm 26 is extencfing up andforward so thatthe wheel 15 engagesthstread 6. Thewheei 22 isthen titted olf(Flgure 8)from its ground engaging position so as to clear the riser 7. The wheeled chair may then, as shown in Figure 9. be pushed or powered so as to move the chair up the step.

Usually the front wheels are simply passive casters and the rear wheels at the wheelchair are powered and have the embodiment shown in Figure 2 and 10 - 11. and the powered wheels will push the wheeled chair and the front asters Up the step.

When the wheeled chalr'a rear wheels 20 and 222 meet the step. the powered rear wheels negotiate the step by uslng the planetary drive arrangement 280.

The operation of the system is controlled by the ller. a block diagram of ive components of which is shown at Figure 17, 18 and 19. the controller being indicated at 100. The controller of preferred embodiments of the present invention may be in the form of such a machine or smartphone or other computer. generally as hereinafier described.

The-control system 100 includes a controller 101 having a processor 102. instructions and data to control ion of the processor 102 in accordance with the present invention are stored in a memory 103 which Is In data communication with the processor 102.

Typically, the control system 100 will e both volatile and non- volatile memory and more than one of each type of memory. with such memories being collectively nted by the memory 103.

Figure 18 shows a block‘dlagram of the main components of an exemplary memory 103. The memory 103 includes RAM 103A, EPROM 1038 and a mass storage device 1030. The RAM 103A typically temporarily holds program files for ion by the processor 102 and related data. The EPROM 1038 may be a boot ROM device and/or may contain some sysmm or control related code. The mass storage device 1030 is typically used to store control programs, the integrity ofwhich may be verified and/or authenticated by the processor 102 using protected code from the EPROM 1038 or elsewhere.

The control system has an Input/output (IIO) tion 105 for communicating with a display interface 120. the display interface 120 having several peripheral devices. The output ace 105 andlor the penpheral devices may be Intelligent devices with their own memory for storing ‘ ated instructions and, data for use with the input/output interface or the peripheral devices. in the example shown in Figure 17. the peripheral devices that communicate with the controller 101 comprise one or more sensors and/or actuators arid/or displays 106. a touch screen and/or bank of buttons 107: a printer 109. Additional hardware may be Included as part of the control system 100, or hardware may be d as required for the specific implementation.

In on, the control system 100 may Include a communications interface, for example a network card 112. The network card may, for example, send status information, accounting information or other information to a central controller, server or database and receive data or commands from the central controller, server or database.

It is also le for the operative components of the control system 100 to be distributed. for example input/output devices 106, 107. 108, 109. 110, 111 may be provided remotely from the controller 101. ' Figure 19 shows a centrol system 200 in accordance with an tlve ment The control system 200, includes a network 201. which for example may be an Ethernet network. a LAN or a WAN. In this example. three 16 banks 203 ofhrro controllers 202 are connected to the network 201. The control systems 202 provide a user interface and may be the same as the control systems 100 shown in Figures 17 and 18. or may have simplified functionality ing on the requirements for enting control. While banks 203 of two controllers are Illustrated in Figure 19, banks of one. three or more control systems are also envisaged.

One or more actuators 204 may also be connected to the network 201.

The actuators 204 may, for example, be ated with one or more banks 203 of control systems. The actuators 204 may be used to implement outcomes associated with control situations associawd with the control systems 202.

In a thick client embodiment, a control server 205 implements part of the control system using a control machine 202 and the l machine 202 implements part of the control algorithm. With this embodiment, as both the control server 205 and the control machine 202 implement part of the control algorithm. they collectively provide a ller. A database management server 206 may manage storage of l programs and associated data for downloading or access by the control s 202 in a database 206A.

In variation of the above thick client embodiment, the l machine 202 may implement the control, with the control server 205 t’unctbning merely to serve data indicative of a control algorithm to the l machine 202 for implementation.

With this Implementation, a data signal ning a oornputer program usable by the client What to implement the control system may be erred from the controlserver to the client terminal, for example In response to a request by the client terminal.

In a thin client embodiment. the control sewer 206 implements most or all of the control using a l machine 202 and the control machine 202 essentially provides only the control interface. With this embodiment, the control server 205 provides the controller. The control machine will receive control instructions, and pass the instrtlctlons to the control server which will process them and return control outcomes to the actuators for implementation.

In a thin client embodiment. the control machines could be computer terminals. e.g. PCs g software that provides a player Interface operable using standard computer input and output components.

It will be appreciated that support attachments in accordance with the preferred embodiments of the invention are suitable for being incorporated with powered wheelchairs and In that case. the support attachments can be used with rear—wheel- " drive wheelchairs such as for example those described in the above paragraph, or with -vlmeeI-drive hairs or mid-wheel drive wheelchairs. the latter ofwhich typically have two sets of castor wheels respectively toward the front and back of the wheelchair on either side of the drive wheels.

It will be iated by persons skilled in the an that numerous variations and/or modifications may be made to the ion as shown in the specific embodiments without departing from the spirit or scope of the Invention as y described. The present embodiments are, therefore, to be considered in all respects as illustrative and not motrlctlve

Claims (19)

Claims:

1. A step-climbing attachment for a wheeled chair, the attachment including: a wheel-mounting chassis for mounting wheels; a first and a second wheel each mounted on the wheel-mounting chassis for rotation about their axes; the first and second wheels each being adapted to move relative to the other, the relative movement in use being between a ground engaging position and a step-engaging position so that in use at least one of the first or second wheels engages a step; and respective link arms connected to the chassis so as to mount the first wheel and the second wheel to the chassis and allow each wheel to swing from the ground engaging position to the step-engaging position; at least one of the wheels having a hub and said at least one wheel having a motor and gearbox d within the hub, said motor and gearbox being connected to the tive link arms so as to pivot the other of the first or second wheels into a step engaging on.

2. The step-climbing ment in accordance with claim 1 wherein the attachment is mounted to a stub axle on a wheel chair so that the wheel-mounting s pivots thereabout.

3. The step-climbing attachment in accordance with claim 2 wherein the first and second wheels both include a hub for rotating a main castor wheel body thereabout.

4. The step-climbing ment in accordance with claim 1 wherein the link arms are linked so as to form a four bar linkage.

5. The step-climbing attachment in accordance with claim 4 wherein the four bar linkage is arranged so that first and second links of the four bar linkage are pivotally mounted at spaced-apart locations on the wheel-mounting chassis and are ted at their distal ends by a connecting arm.

6. The step-climbing attachment in accordance with claim 5 wherein the first link is shorter than a fourth link so as not to encounter a jam when in operation.

7. The step-climbing attachment in accordance with claim 6 wherein at least one link includes a spring and/or damper arrangement to provide an at least partially suspended chassis.

8. The step-climbing ment in ance with claim 4 wherein the wheel hub connects to a distal end of the first link of the four-bar linkage.

9. The step-climbing attachment in accordance with claim 4 wherein a motor plate is provided and mounts to a distal end of the second link of the four-bar linkage.

10. The step-climbing attachment in accordance with claim 1 wherein one of the first or second wheels is disposed in use on the chassis in a position relatively forward of the other wheel so as to facilitate step climbing or descending.

11. The step-climbing attachment in accordance with claim 10 wherein the chassis is disposed between the first and second wheels.

12. The step-climbing ment in accordance with claim 2 wherein a ng l motor is provided to facilitate rotation of the stub axle for steering control in se to operator input.

13. The step-climbing attachment in accordance with claim 1 wherein the first wheel is a powered wheel ly to provide propulsion to the chassis.

14. The step-climbing attachment in accordance with claim 13 wherein the second wheel is in the form of a planetary wheel assembly and is mounted so as to orbit the first powered wheel assembly.

15. The step-climbing attachment in accordance with claim 14 wherein an idler wheel is ed and is disposed to be in contact with the tread of the powered wheel assembly, and in operation is disposed between the first and second wheels.

16. The step-climbing attachment in ance with claim 14 wherein two planetary wheels are provided.

17. The limbing attachment in accordance with claim 16 wherein a differential or belt system is used so that the motor is a drive motor and used for propulsion and climbing.

18. The step-climbing attachment in accordance with claim 17 wherein a two stage planetary gearbox is provided with a third stage reduction so as to isolate and engage a wheel arm to cause the movement of the planetary wheel into a ngaging position.

19. A self-propelled wheeled chair ing a step-climbing attachment according to any one of claims 1 to 18.