GB2551570A

GB2551570A - Transportation device

Info

Publication number: GB2551570A
Application number: GB1610997.7A
Authority: GB
Inventors: Artemev Timur; Anatolevich Annenkov Grigory
Original assignee: Uniwheel Ltd
Current assignee: Uniwheel Ltd
Priority date: 2016-06-23
Filing date: 2016-06-23
Publication date: 2017-12-27
Also published as: GB201610997D0

Abstract

A self-balancing transportation device having an adjustable track. The device includes a first ground contacting member 100 and a second ground contacting member 101 adapted to contact a ground surface at a respective contact position. A distance between the contact positions X1 is adjustable so as to adjust a track of the transportation device. The adjustment may be achieved by altering an inclination on the wheels 100, 101 of the device. The adjustment may be made in dependence on the speed of travel of the device.

Description

TRANSPORTATION DEVICE

FIELD OF THE INVENTION

This invention relates to the field of transportation devices, and in particular to selfbalancing transportation devices having at least two ground contacting members.

BACKGROUND OF THE INVENTION

Powered self-balancing vehicles for transporting loads, such as packages or individuals, are known. In particular, it is known for a powered self-balancing device to comprise one or more wheels aligned in a single axis, for example, a single wheel positioned between a user’s legs.

Typically, such powered self-balancing transportation devices have an electronic and/or mechanical system that is adapted to control the rotation of a wheel so as to control the fore-and-aft balance of the device. In such devices, such as those described by US Patent Number US 6,302,230, a sensor and an electronic arrangement are provided. Information detected by the sensor and electronic arrangement is passed to a motor, which drives the wheel in the appropriate direction and at a suitable speed so as to maintain or preserve fore-and-aft balance.

Self-balancing devices are often seen as having a steep learning curve, such that an inexperienced or unpractised user may have difficulty in learning how to use and safely mount the device appropriately.

SUMMARY OF THE INVENTION

The invention is defined by the claims.

According to an aspect of the invention there is provided a self-balancing powered transportation device, comprising: a ground contacting arrangement comprising: a first ground contacting member adapted to contact a ground surface at a first contact position; and a second ground contacting member adapted to contact the ground surface at a second contact position; a load support adapted to support a load; a drive arrangement adapted to drive at least one of the ground contacting members; and a balance control system adapted to maintain a fore-aft balance of the self-balancing powered transportation device; wherein the transportation device is operable in at least: a first configuration, in which the first contact position and the second contact position are spaced a first distance apart; and a second configuration, in which the first contact position and the second contact position are spaced a second, different distance apart.

In other words, there is provided a concept of adjusting a track of a self-balancing powered transportation device having at least two ground contacting members.

It should be apparent that the device may be operated (e.g. a user may be transported by the transportation device) when the device is in the first configuration and when the device is in the second configuration. Put another way, the balancing system may maintain a fore-aft balance of the transportation device both when the transportation device is in the first configuration and when the transportation device is in the second configuration.

It may be understood that the ground contacting arrangement of the transportation device is adapted to contact a ground surface with at least two contact points so as to contact the ground surface at at least two contact positions, wherein the transportation device is operable in a first configuration, in which the first contact position and the second contact position are spaced apart; and a second configuration, in which the first contact position and the second contact position are more proximate to one another or vice versa.

In such embodiments, in the first configuration, the transportation device may have a wider track than when in the second configuration. In other words, in the first configuration, the contact positions are separated or spaced further apart than when the transportation device is in the second configuration.

In this way, a stability and manoeuvrability of the transportation device with respect to, for example, speed of the transportation device may be readily adjusted.

By way of explanation, it may be appreciated that when a transportation device has a narrow track (i.e. the first contact position and the second contact position are proximate to one another), the device has a low lateral stability and low manoeuvrability at low speeds, but may have a good lateral stability and high manoeuvrability at high speeds (e.g. due to an increased ease in maintaining balance). When a transportation device has a low lateral stability, it may be difficult for a user or load to be positioned on the load support (e.g. there is a high difficulty of a user mounting the transportation device).

However, although devices with a wide track base may have high lateral stability and high manoeuvrability at all speeds (especially if the wheels of such a device may turn in opposing direction when performing a turning manoeuvre), the manoeuvrability of the device may be less intuitive than that of a transportation device with a narrow track base. This is because a device with a narrow track base may turn using the phenomenon of precession (i.e. a load/user may lean to a side causing the device to turn). Such a phenomenon may be unavailable to a wide wheel-based device. Turning (using the effect of precession) may also be seen as a more natural or intuitive method of turning a transportation device as a user simply needs to lean the device to turn the device. A narrow track also provides a narrowed profile of the transportation device.

It has also been recognised that a safety or ease of use of the transportation device may be dependent upon a width of the track base, as there is an increased difficulty of balancing a load on the load support if the device has a low lateral stability (i.e. narrow track base operating at low speeds).

The present invention therefore recognises the desire for adjusting a track width of a transportation device. In particular, it has been recognised that such an adjustable track size is of particular advantage for a self-balancing transportation device, due at least to the above described trade-off between manoeuvrability, safety, stability and speed. As self-balancing transportation devices typically operate on the principle of a person leaning to turn (later described), there is a particular desire to have a narrow track with high stability at low speeds.

Adjusting a stability of the device may also allow a safety of the transportation device to be improved, as a device with a wider track base may more readily allow a user (or load) to be positioned on the load supports (e.g. as the likelihood of the device unintentionally tipping will be reduced). Thus, an ease of accessibility of the transportation device may be improved. It may therefore be understood that there is a link between the stability of the transportation device, and a safety for a user stepping on and off the transportation device.

In preferable embodiments, the track is adjusted based on at least a control parameter of the transportation device. Put another way, a distance between the two contact points of the ground contacting arrangement may be adjustable based on a control parameter of the transportation device.

Purely by way of example, the control parameter may comprise one or more of the following: a speed of the transportation device; an acceleration of the transportation device; a distance travelled by the transportation device; a time since power on the transportation device; an average speed of the transportation device; a fore-aft balance of the transportation device; a fore-aft balance of at least one ground contacting member of the transportation device; an amount of desired yaw rotation of the transportation device; and a torque applied by the drive arrangement.

In an embodiment, the transportation device may further comprise a control system adapted to control the distance, separation or spacing between the first contact position and the second contact position.

In other words, a control system may be provided to actively adjust or manage the track of the powered transportation device. In particular, the control system may be adapted to determine or obtain a value of a control parameter and, based on the obtained value, control a distance between the contact positions of the two ground contacting members.

In some embodiments, an angle of the first ground contacting member relative to the second ground contacting member is adjustable so as to adjust the spacing between the first contact position and the second contact position. That is to say, in embodiments, in order to adjust the spacing between the first contact position and the second contact position, the angle between the first ground contacting member and the second ground contact member may be respectively adjusted with respect to a direction perpendicular or orthogonal to the ground surface.

It may be recognised that an axis of rotation of the first ground contacting member and an axis of rotation of the second ground contacting member is adjustable, so as to perform at least one of the following: adjust the distance between the first contact position and the second contact position; adjust an angle of the first ground contacting member and the second ground contacting member with respect to a ground surface; adjust an angle of the first ground contacting member and the second ground contacting member with respect to one another; adjust an angle of the first ground contacting member and the second ground contacting member with respect to a direction of travel; and adjust an angle of the first ground contacting member and the second ground contacting member with respect to a direction perpendicular to the ground surface.

Optionally, moving the first ground contacting member with respect to the second ground contacting member angles the first ground contacting member with respect to the second ground contacting member. Put another way, in some embodiments, as the distance between the contact position changes, so the angle between the first ground contacting member and the second ground contact member changes.

There is also proposed an embodiment further comprising a hinging mechanism adapted to rotatably or pivotably couple the first ground contacting member and the second ground contacting member. Put another way, the first ground contacting member may be hinged to the second ground contacting member, so as to allow the first ground contacting member to rotate with respect to the second ground contacting member. Preferably, the hinging mechanism is positioned towards the upper end (i.e. positioned away from the ground surface) of the first and second ground contacting members.

In at least one embodiment: at a first speed of the transportation device, the first ground contacting member and the second ground contacting member are angled with respect to one another; and at a second speed of the transportation device, the first ground contacting member and the second ground contacting member lie substantially parallel to one another. Preferably the first speed is less than the second speed, such that when the speed of the transportation device is lower, so the ground contacting members are further apart.

In optional embodiments, the first ground contacting member and the second ground contacting member are substantially parallel with one another; and a distance between the first ground contacting member and the second ground contacting member is adjustable so as to adjust the spacing between the first contact position and the second contact position.

In some embodiments the distance between the first ground contacting member and the second ground contacting member is adjustable between Omm and 2000mm. Put another way, the distance between the first ground contacting member and the second ground contacting member may be varied within a predetermined range. Further proposed is a concept of a minimum distance (below which the ground contacting members are unable to move closer together) and a maximum distance (above which the ground contacting members are unable to move further apart). Put another way, the distance between the first and second ground contacting members may vary between a minimum and a maximum distance.

In preferable embodiments, the maximum distance to which the contact positions are separable is at least 100mm, in even more preferable embodiments, the maximum distance to which the contact positions are separable is at least 200mm, for example, at least 500mm, for example, at least 1000mm. By way of further example, a maximum distance may be 2000mm, such that the first ground contacting member and the second ground contacting member may be separated by up to 2000mm.

In other embodiments, the maximum distance to which the contact positions are separable is less than 100mm, in yet other embodiments, the maximum distance to which the contact positions are separable is less than 200mm, for example, less than 500mm, for example, less than 1000mm.

Preferably, the minimum distance to which the contact positions are separable is at least the width of the first ground contacting member or the second ground contacting member. In other words, in preferable embodiments, the ground contacting members are positionable directly side by side.

The skilled person will readily appreciate that above identified distances are merely exemplary embodiments. The skilled person may select a particular range using identified maximum and minimum values to be used in different embodiments to provide various advantages.

Optionally, the first ground contacting member is movable with respect to the second ground contacting member in response to a user input. In other words, a user may input a user signal (using, for example, a Bluetooth communication methodology) and the distance between the contact positions may be adjusted based on this signal.

Optionally, the self-balancing powered transportation device comprises a control parameter detection unit adapted to detect a control parameter of the unicycle device.

BRIEF DESCRIPTION OF THE DRAWINGS

Examples of the invention will now be described in detail with reference to the accompanying drawings, in which:

Figure 1 is a view of a transportation device according to an embodiment of the invention;

Figure 2 is a view of a ground contacting member and drive arrangement of a transportation device according to an embodiment;

Figure 3 is a second view of the transportation device according to the embodiment of the invention;

Figures 4A and 4B illustrate a coupling arrangement for a transportation device according to an embodiment;

Figure 5 illustrates a transportation device according to another embodiment;

Figure 6 illustrates a transportation device according to yet another embodiment;

Figure 7 is a view of a transportation device according to another embodiment.

Figure 8 is a detailed view of a hinging mechanism of a transportation device according to an embodiment;

Figures 9A and 9B are plan views of the hinging mechanism in different configurations;

Figure 9C illustrates various configurations of a transportation device according to an embodiment;

Figures 10A and 10B illustrate embodiments of the transportation device;

Figure 11 illustrates an embodiment of the transportation device; and

Figures 12A to 12D illustrate various control systems for a transportation device according to various embodiments.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The invention provides a self-balancing transportation device having an adjustable track. The device includes a first ground contacting member and a second ground contacting member, each adapted to contact a ground surface at a respective contact position. A distance between the contact positions is adjustable so as to adjust the track of the transportation device.

The term vertical, as used herein, means substantially orthogonal to a ground surface. The term lateral, as used herein, means substantially parallel to the ground surface. Also, terms describing positioning or location (such as above, below, top, bottom, etc.) are to be construed in conjunction with the orientation of the structures illustrated in the diagrams.

The diagrams are purely schematic and it should therefore be understood that the dimensions of features are not drawn to scale. Accordingly, the illustrated thickness of any of the components or features should not be taken as limiting. For example, a first component drawn as being thicker than a second component may, in practice, be thinner than the second component. It will also be understood that identical reference numerals in the Figures indicate the same or similar features. A general concept of the invention may be understood with reference to Figures 1 and 2. Firstly, with particular reference to Figure 1, there is depicted a self-balancing transportation device 1. The transportation device 1 comprises a ground contacting arrangement comprising a first ground contacting member 100 and a second ground contacting member 101. Each ground contacting member 100, 101 comprises a respective wheel 110, 111 adapted to contact a ground surface 900 at a respective contact position 951, 952.

Put another way, in embodiments, each ground contacting member is associated with a respective wheel 110, 111, the wheel(s) 110, 111 being adapted to contact a ground surface 900 at a respective contact position 951, 952 or contact point. In other words, there may be defined a first contact position 951 or first contact point (associated with the first wheel 110, and thereby the first ground contacting member 100) and a second contact position 952 or second contact point (associated with the second wheel 111, and thereby the second ground contacting member 101).

It will be apparent that there may be defined a distance x i or spacing between the contact positions 951, 952 between the first wheel 110 and the second wheel 111. Put yet another way, there may be considered a ‘track’ of the transportation device, the track being the distance xi between the centre line of the first ground contacting member and the centre line of the second ground contacting member, when measured in a direction perpendicular to the fore-aft direction of the transportation device

For the avoidance of doubt, although herein described as such, references to a ground contacting arrangement are not limited to embodiments in which wheels are present, but may instead refer to embodiments comprising any at least two ground contacting members (e.g. two or more caterpillar tracks). Thus the term ‘ground contacting member’ is not limited to simply a wheel, but may also be considered to be any ground contacting member having a controllable drive, for example, a caterpillar track.

Reference to a contact position should be understood to be a position or point at which a ground contacting member makes contact with the ground surface. This will generally be assumed to be the centre point of the contact patch of the ground contacting member. Typically, when a ground contacting member comprises a wheel the contact position may be approximated by identifying the centre line of the wheel.

For the avoidance of doubt, specific reference to a “wheel” should be taken to mean a generally circular unit adapted to rotate about an axis to propel the transportation device in a direction during use. The wheel may therefore be formed from one or more tyres and/or hubs that are coupled together (via a differential, for example). For example, an embodiment may comprise a single hubless wheel having a single hubless rim with a plurality of separate tyres fitted thereon. Alternatively, an embodiment may comprise a single hubless wheel formed from a plurality of hubless rims (each having a respective tyre fitted thereon), wherein the plurality of hubless rims are coupled together via a differential bearing arrangement. A wheel may therefore be considered as any element adapted to roll or otherwise rotate with respect to a ground surface (e.g. a castor, a roller and so on).

The transportation device 1 further comprises a first load support 120 and a second load support 121. In embodiments, each load support is a foot support adapted to support a foot of a user thereon. In other words, each load support is adapted to support a weight of the user. In other embodiments, each load support (or the combination of the load supports) is adapted to support a load (e.g. a non-human weight, such as luggage) thereon. In some embodiments, the transportation device may comprise only a single load support.

As shown, the load support(s) may be positioned on the exterior of the ground contacting member (i.e. outwardly projecting from the transportation device). In other embodiments, the load support(s) may be positioned between the first and second ground contacting members, such that a load is support between the ground contacting members. In yet further embodiments, the position of the load support relative to the ground contacting members may be adjusted as the transportation device moves from the first configuration to the second configuration, as described in detail below. It some embodiments, when the transportation device is in at least one particular configuration, the load supports are positioned to the exterior of or outside of the contact positions. In other words, the position of the load support with respect to the contact position(s) and/or ground contacting members may vary based on the configuration of the transportation device.

For the purposes of further explanation, an embodiment of a ground contacting member and components associated therewith may be described with reference to Figure 2. As the first ground contacting member 100 and the second ground contacting member 101 operate in substantially the same manner, only the first ground contacting member 100 shall be hereafter described.

Specifically, Figure 2 illustrates an exploded view of components associated with the first ground contacting member 100, namely a first wheel 110 and a drive arrangement 135. The first wheel 110 is a wheel adapted to rotate about the drive arrangement 135.

In other words, a drive arrangement 135 may be formed as an aspect of the ground contacting member 100.

Rotation of the first wheel 110 is driven by the drive arrangement 135 according to a hereafter described embodiment. The drive arrangement 135 includes guide wheels 140 attached to an outwardly facing side of respective batteries 145. In this embodiment, there are two pairs of angled guide wheels 140, wherein the two guide wheels in each pair are tapered or conical such that they have a sloped surface which is not perpendicular to the radial plane of the first wheel 110. Put another way, the contact surface of each guide wheel is inclined with respect to the radial plane of the first wheel 110 or ground contacting member 100. The guide wheels 140 of each pair are also positioned spaced apart to provide a gap between the two guide wheels of a pair. A rib 150 is provided around the inner rim of the first wheel 110 and fits into the gap between the two guide wheels 140 in each pair. The guide wheels 140 are therefore adapted to contact with the inner rim of the first wheel 110 and hold the first wheel 110 in place by way of the rib 150. Of course, it will be appreciated that other arrangements, including those with only one guide wheel per battery 145, or even only a single guide wheel, are possible.

The batteries 145 are mounted on a motor 155 which drives a pair of drive wheels 160 positioned at the lowermost point along the inner rim of the first wheel 110. The batteries 145 supply power to motor 155 and, in this embodiment, there are two batteries in order to create a balanced distribution of volume and weight. However, it is not necessary to employ two batteries 145. Also, alternative energy storage arrangements may be used, such as a flywheel, capacitors, and other known power storage devices, for example.

The drive arrangement 135 is adapted to be fitted inside the ground contacting member 110. In other words, the drive arrangement is sized and shaped so that it can be positioned in the void defined by the inner rim of the first wheel 110. Further, the drive arrangement 135 is movable between a locked configuration and an unlocked configuration.

In the locked configuration, when fitted inside the first wheel 110, the drive arrangement 135 engages with the rim of the wheel 110 to prevent its removal from the wheel. Here, in the embodiment shown, the guide wheels 140 contact the inner rim of the first wheel 110 and hold the first wheel 110 in place by way of the rib 150 when the drive arrangement is in the locked configuration.

In the unlocked configuration, when fitted inside the wheel 110 or ground contacting member 100, the drive arrangement 135 may disengage with the rim of the first wheel 110 to permit its removal from the ground contacting member. Here, in the embodiment shown, the drive arrangement contracts in size when moved from the locked configuration to the unlocked configuration so that the guide wheels 140 no longer contact the inner rim of the first wheel 110 and no longer hold the first wheel 110 in place by way of the rib 150. Such reduced size (e.g. diameter) of the drive arrangement 135 when in the unlocked configuration thus enables the drive arrangement 135 to be removed from first wheel 110, and thereby the ground contacting member 100.

It will therefore be understood that the drive arrangement 135 of the illustrated embodiment can be quickly and easily connected or removed to/from the ground contacting member 100 for repair or replacement, for example. Arranging the drive arrangement 135 in the unlocked configuration permits its removal or fitting from/to the ground contacting member 100 (because, for example, its dimensions when in the unlocked configuration permit it to fit inside the ground contacting member). When fitted inside the wheel 110, the drive arrangement can be arranged in the locked configuration so that it engages with the rim of the wheel 110 to prevent its removal (because, for example, its dimensions when in the locked configuration prevent the drive arrangement from being removed from the ground contacting member).

As briefly indicated before, when the drive arrangement 135 is fitted inside the wheel and in the locked configuration, a pair of drive wheels 160 is adapted to contact the inner rim of the wheel 110. Here, the pair of drive wheels comprises first and second rollers that are inclined with respect to the radial plane of the ground contacting member. By way of contact with the inner rim of the wheel 110, the drive wheels transmit torque from the motor 155 to the wheel 110. It will be understood that this drive system operates by friction and it may be preferable to avoid slippage between the drive wheels and the inner rim of wheel 110.

Positioning the drive wheels at the lowermost point enables the weight of a user or load to provide a force that presses the drive wheels against the inner rim of the wheel 110, thereby helping to reduce or avoid slippage.

In other conceivable embodiments, rather than the drive arrangement comprising a pair of drive wheels 160 to drive the wheel 110 (and guide wheels 140), the drive arrangement 135 instead comprises a stator and a rotor (the latter being coupled to or forming part of the first wheel 110). In this way, the drive arrangement may act as an outrunner motor, wherein an outer shell (i.e. rotor) of the drive arrangement directly drives a wheel or tyre of the wheel about a stator of the motor. The stator may, for example, comprise windings which may be alternately pulsed, and the rotor may comprise a plurality of permanent magnets. Control of the motor speed and/or acceleration may thereby be controlled by controlling the current through the winding(s). Such a drive arrangement operates on the well-known principles of a standard electric motor. It has been recognised that such a described outrunner motor provides a greater amount of torque than a conventional (i.e. inrunner) motor.

In such embodiments, the unicycle device may comprise a bearing system adapted to couple the ground contacting member to the stator, thereby allowing the ground contacting member to rotate about the stator of the drive arrangement.

The drive arrangement 135 includes a gyroscope or accelerometer system 170 (i.e. a balance control system) that senses forward and backward tilt of the drive arrangement in relation to the ground surface and regulates the motor 155 accordingly to keep the drive arrangement upright. In this way, a user of the transportation device is provided a way of controlling the acceleration and deceleration of the transportation device by varying the pressure applied to various areas of the load supports 121,122. It also enables the transportation device to self-regulate its balance in the fore-and-aft plane. In other words, the transportation device may regulate or maintain pitch of the transportation device relative to a ground surface.

In some embodiments, the wheels of each ground contacting member are driven independently of one another. That each to say, each ground contacting member 100, 101 may be associated with its own respective drive arrangement 135 and associated balance control system adapted to independently control a rotation of a wheel of the ground contacting member.

In particular embodiments, a tilting of the first and second ground contacting members may be independent of one another. A balance control system may be associated with each ground contacting member, so as to control and/or regulate the motor of each drive arrangement 135 associated with each respective ground contacting member.

In such embodiments, a user may control a rotation of the transportation device 1 by controlling a pitch of each drive arrangement 135 associated with a respective ground contacting member 100, 101. In other words, each drive arrangement (and each ground contacting member) is associated with its own balance control system, wherein the balance control system controls a fore-aft balance of the respective drive arrangement/ground contacting member so as to control a fore-aft balance of the transportation device.

For example, if a user pitches a first drive arrangement (associated with the first ground contacting member 100) in a first direction, and a second drive arrangement (associated with the second ground contacting member 101) in an opposing direction, the transportation device may rotate (e.g. without the need for an overall forward or rearward movement of the transportation device). The user may control the pitch, for example, by controlling an amount of pressure applied to various areas of the load supports 121, 122.

Such embodiments allow for a narrow turning circle, as the device may be rotated (e.g. on the spot).

In such embodiments, the first ground contacting member 100 and the second ground contacting member 101 may be adapted to rotate with respect to one another. In other words, the first ground contacting member and the second ground contacting member may be rotatably coupled together (i.e. connected via a rotating hinge).

In other, preferable, embodiments, the driving of the first ground contacting member is linked to the driving of the second ground contacting member (and vice versa). In such embodiments, as a first drive arrangement (associated with the first ground contacting member 100) is pitched forward, both the first ground contacting member and the second ground contacting member are driven simultaneously. In other words, a tilting of the first ground contacting member may cause a same tilting of the second ground contacting member and vice versa.

In similar embodiments the driving of the first and second ground contacting member is based on a tilting of the load support(s). In other words, a single balance control system may attempt to maintain a fore-aft balance of the load support(s), said load supports being linked together.

Proposed embodiments may thereby only comprise a single balance control system. This may be of particular advantage in reducing the cost and weight of a transportation device.

In order to control a rotation of such a transportation device 1, that is to perform a turning manoeuvre, the user may lean or tilt the (ground contacting members or load supports of the) transportation device sideways (i.e. from side-to-side). The gyroscopic effect of the lean or tilt will cause the device to begin performing a turn (e.g. undergo a banked turn). This well-known phenomenon may also be called precession. In this way, the user (e.g. supported by the load supports) is given a degree of control over the direction of travel by shifting his weight on the load supports 121, 122 so as to cause the device to lean and thereby change direction. In other words, the user may steer the transportation device by changing an amount of leaning (by shifting a body weight of the user).

The transportation device may thereby be thought to lean in at least a fore-and-aft direction (thereby controlling an acceleration/deceleration) and in a side-to-side direction (thereby controlling a turn).

In at least one embodiment, there is further provided one or more weight sensors, pressure sensors or force sensors positioned on or in the load support(s). Such force sensors may be adapted to detect a force (e.g. weight or applied pressure) being applied to various parts of the load support. The drive arrangement 135 is adapted to drive the first ground contacting member and the second ground contacting member based on a signal received from such sensors.

Provision of a plurality of weight sensors may permit a load to indicate when and/or in which direction a turning manoeuvre is to be performed. In other words, a user or load may provide input to the pressure/force sensors in order to indicate when a turning manoeuvre (e.g. ground contacting members rotating in opposite directions) is to be performed.

By way of example, there may be considered an embodiment comprising a first and second force sensor respectively positioned at a fore and aft end of the first load support, and a third and fourth force sensor respectively positioned at a fore and aft end of the second load support. In response to a particular force (e.g. minimum force) being sensed at the first and fourth force sensor, the device may perform a turning manoeuvre in a first direction. In response to a particular force (e.g. minimum force) being sensed at the second and third force sensor, the device may perform a turning manoeuvre in a second, opposite direction.

In further embodiments, in response to a particular force (e.g. minimum force) being sensed at the first and third force sensor, the device will accelerate. Optionally, in response to a particular force (e.g. minimum force) being sensed at the second and fourth force sensor, the device will decelerate.

It will be apparent that such a transportation device still comprises a balance control system adapted to maintain a fore-aft balance of the transportation device.

Provision of such weight sensors thereby allows a device to rotate with a minimal turning circle (i.e. on the spot), without the need for more than one balance control system.

In an embodiment the transportation device comprises a first drive arrangement for the first ground contacting member and a second drive arrangement for the second ground contacting member, but only a single balance control system. Such a transportation device may comprise one or more force sensors to allow a user to indicate when and/or in which direction they wish to perform a turning manoeuvre.

It has been recognised that independently rotating wheels may be more dangerous or less safe when moving at a high speed (as a device may unexpectedly rotate). Thus, in at least one embodiment, the transportation device may be further switchable between at least a first mode (in which the wheels may rotate independently) and a second mode (in which the wheels may not rotate independently of one another). The switching of the modes may be based on a control parameter of the transportation device (e.g. a speed of the transportation device).

Now that an understanding of a transportation device has been elucidated, a concept of the invention will be understood from the following description and with reference to at least Figure 1. The transportation device 1 is adapted such that a distance xi between the first contact position 951 and the second contact position 952 is adjustable. That is to say, the size of the track of the transportation device may be adjusted.

Put another way, the transportation device may be operable in at least two configurations or modes, between which a distance between the first contact position and the second contact positions is altered or adjusted. By way of example, the first contact position (first wheel) and second contact position (second wheel) may be configured to be in at least a first configuration (in which they are spaced apart) and in a second configuration (in which they are more proximate to one another). Thus, the transportation device may be associated with at least two configurations.

The adjustment may, for example, be based on a control parameter of the transportation device. In alternative embodiments, the adjustment may be effected manually (e.g. using a manual screw thread) so as to allow adjustment of the distance between the first contact position and the second contact position.

By way of example, the distance or spacing between the first contact position 951 and the second contact position 952 may be adjusted based on a speed of the transportation device. At a low speed (e.g. < 5kph), the distance xi may be a first predetermined distance, whereas at a high speed (e.g. >5kph), the distance xi may be a second, lower predetermined distance. That is to say, the higher the speed of the transportation device, the closer the first ground contacting member and the second ground contacting member are to one another.

Other control parameters on which the proximity of the first and second contact position may be based will be readily apparent to the person skilled in the art. By way of example only, such parameters may include: a distance travelled by the device, a time since power on the device, an acceleration of the device, a torque applied by the drive arrangement 135 of the device, user characteristics, a detected amount of lean of the device and so on.

It will therefore be apparent that the transportation device may comprise a control parameter detection unit adapted to detect or sense a control parameter (e.g. a speedometer or an accelerometer). Such a control parameter detection unit may be adapted to generate a control parameter signal based on a detected control parameter (e.g. a speed or distance travelled). The control parameter detection unit may be embodied as an aspect of the balance control system (e.g. to detect acceleration / amount of lean) or the drive arrangement (e.g. to detect an amount of torque applied or a speed).

With further reference to Figure 3, a particular embodiment of the transportation device 1 may be further described, in which the transportation device 1 further comprises a control system 300 adapted to control a distance between the first contact position 951 and the second contact position 952.

The control system 300 comprises a first drive 310 adapted to control a distance between lower portions of the first and second ground contacting members, and thereby a size of a track of the transportation device.

The first drive 310 may be housed in a drive housing 305. The first drive 310 is coupled to a lower portion 190 of the first ground contacting member 100 via a first screw 315. Similarly, the first drive 310 is coupled to a lower portion 191 of the second ground contacting member 101 via a second screw 316.

The first and second screws 315, 316 may be coupled to their respective ground contacting member via a respective coupling arrangement 318, 319, which for the purposes of clarity and further explanation, may be described with reference to Figures 4 A and 4B.

An exemplary coupling arrangement 318 comprises a screw receiving portion 410 adapted to receive the first screw 315. Thus, as the screw rotates with respect to the screw receiving portion, the coupling arrangement is brought towards the first drive 310 and the drive housing 305. In other words, the first drive 310 may rotate the first screw 315 so as to change a position of the coupling arrangement 318 (and thereby the lower portion of the ground contacting member) with respect to the first drive 310.

The coupling arrangement 318 may further comprise a spring component 420 and an actuating component 430. The actuating component may be controlled or activated to slide the coupling arrangement with respect to the ground contacting arrangement (as in Figure 4B), providing at least one additional degree of freedom. The spring component 420 is adapted to restore the coupling arrangement to its original position (as in Figure 4A) when the actuating component is no longer controlled or activated.

Referring back to Figure 3, it will therefore be apparent that a distance between the first drive 310 and the first ground contacting member 100 is controlled by rotating the first screw 315 with respect to the first coupling arrangement 318. Similarly, a distance between the first drive 310 and the second ground contacting member 101 is controlled by rotating the second screw 316 with respect to the second coupling arrangement 319.

In this way, a distance between the lower portion 190 of the first ground contacting member 100 and the first drive 210 and the lower portion 191 of the second ground contacting member 101 and the first drive 210 may be controlled. As shown in Figure 3, as a distance between the first drive 310 and the first ground contacting member 100 increases, so a distance between the lower portions 190, 191 of the first ground contacting member 100 and the second ground contacting member 101 correspondingly increases. Thus, control of the distance between the lower portions of the first and second ground contacting members is permitted.

By controlling a distance between lower portions of the first and second ground contacting members, it will be apparent that the first drive 310 is adapted to control the distance xi between respective contact positions of the first and second ground contacting member.

Preferably, the distance xi between the respective contact positions is controlled to vary up to 2000mm, for example, up to 1000mm, for example, up to 500mm. In more preferable embodiments, the distance xi is controllable up to a maximum of 100mm, as this would allow a user to comfortably place their feet on either side of the transportation device, whilst having an increased level of support (at least when the transportation device is stationary).

Preferably, the minimum distance between the respective contact positions is such that the ground contacting members are directly side-by-side (i.e. touching along their length). In such embodiments, the two ground contacting members may be analogous to a single wheel, having improved manoeuvrability and a high stability when the transportation device is moving at speed.

It has been recognised that the greater the distance between the contact positions, the more stable the transportation device becomes (at least at low speeds or when the transportation device is stationary). It has also been recognised that the smaller the distance between the contact positions, the greater an ease and intuitiveness of manoeuvring the transportation device (particularly at high speeds) becomes.

It may therefore be preferable to have a large distance between the contact positions when a user is mounting the device (where stability is desired and ease of manoeuvrability is less important), and have a small distance between the contact positions when the user is operating or moving on the device (as lateral stability is then naturally provided by a preservation of momentum, and manoeuvrability is of increased importance). It has been recognised that in preferable embodiments, the distance between the contact positions is based on a speed of the transportation device.

In embodiments, the first ground contacting member 100 and the second ground contacting member 101 are further coupled together by a linking arrangement 320. In the present embodiment, the linking arrangement 320 connects upper portions 192, 193 of the first ground contacting member 100 and the second ground contacting member 101 together. The linking arrangement 320 is further adapted to maintain a same or similar distance between the upper portions 192, 193 of the first ground contacting member 100 and the second ground contacting member 101.

In particular, the linking arrangement 330 may comprise a first linking element 321 rotatably coupled, at a first end, to the upper portion 192 of the first ground contacting member 100 and, at a second end, to the drive housing 305 or the first drive 310. Such a linking arrangement further comprises a second linking element 322 rotatably coupled, at a first end, to the upper portion 193 of the second ground contacting member 101 and, at a second end, to the drive housing 305 or the first drive 310.

In this way, as the upper portions 191, 192 are maintained a same or similar distance from one another, controlling a distance between lower portions of the respective ground contacting members thereby controls an angle of the ground contacting members with respect to one another. Thus the first ground contacting member may be angled with respect to the second ground contacting member by controlling the first drive 310.

Put another way, respective upper portions of each ground contacting member may be maintained or remain substantially proximate to one another, whereas a proximity of lower portions (i.e. more proximate to the ground surface) may be altered so as to adjust an angle of the first ground contacting member with respect to the second ground contacting member.

It may be alternatively understood that an axis about which the first ground contacting member rotates may be angled with respect to an axis about which the second ground contacting member rotates. By adjusting this angle of the axes, so the angle of the first ground contacting member (i.e. the plane of the first ground contacting member) is adjusted relative to the angle of the second ground contacting member (i.e. the plane of the second ground contacting member).

In some embodiments, the first ground contacting member is hinged to the second ground contacting member, such that the second ground contacting member rotates or pivots about the first ground contacting member (and vice versa). A hinging arrangement may be positioned to connect to an upper portion of each of the first and second ground contacting members. In embodiments, the hinging arrangement hinges about an axis lying in a forward and rearward direction of the transportation device. Such a hinging arrangement may replace the linking arrangement as previously described.

It has been herein recognised that controlling an angle of the ground contacting members of the transportation device 1 may be particularly advantageous, as wheels angled toward one another (i.e. having upper portions more proximate to one another) cause the transportation device to move more consistently in a single forward direction, mitigating a ‘weaving’ or ‘snaking’ effect (where the device does not travel in a straight line) of the transportation device.

The control system 300 may be adapted to receive and/or determine a control parameter value. Based on the control parameter value, the control system may adjust the distance between at least the lower portions 190, 191 of the ground contacting members 100, 101 (and thereby the distance between the contact positions 951, 952.

By way of example, the control system 300 may be adapted to obtain a speed value indicative of a speed of the transportation device. The control system may control the distance between the contact position based on the speed value (e.g. proportional to the speed value). For example, if a speed value is below a first predetermined speed vi, the control system may control the distance to be as small as possible. If the speed value is above a second predetermined speed V2, the control system may control the distance to be as large as possible (i.e. as large as permitted). In some further embodiments, when the speed is between vi and V2 the distance xi is proportional to the speed. Put another way, if the distance xi is adjustable between a first distance di and a second distance d2, the distance xi may be increased between these values proportional to a change in velocity between vi and V2.

In other embodiments, the control system 300 may be adapted to obtain values indicative of other control parameters. By way of example, the control system may be adapted to obtain a value indicative of: an acceleration of the transportation device; a distance travelled by the transportation device; a time since power on the transportation device; an average speed of the transportation device; a fore-aft balance of the transportation device; a fore-aft balance of at least one ground contacting member of the transportation device; an amount of desired yaw rotation of the transportation device; a torque applied by the drive arrangement and so on.

In at least one embodiment, the control system is adapted to receive a user input from a user input unit (not shown). Based on the user input, the control system may be adapted to control the distance between the contact positions of the first ground contacting member and the second ground contacting member. In this way, a user may manually control the stability and/or manoeuvrability of the device. The user input may be in the form of a wireless signal, for example, a Bluetooth signal or other suitable wireless communication methods.

Some such suitable wireless communication protocols that may be used to communicate with the control system include an infrared link, Zigbee, Bluetooth, a wireless local area network protocol such as in accordance with the IEEE 802.11 standards, a 2G, 3G or 4G telecommunication protocol, and so on. Other formats will be readily apparent to the person skilled in the art.

In other embodiments, the control system is adapted to control the distance between the contact positions based on a user characteristic, such as an experience level, a weight, an indication of intended usage, an age and so on. The control system may, for example, comprise a user characteristic sensor (e.g. a scale) adapted to obtain such a user characteristic.

In yet other embodiments, the control system is adapted to control the distance between the contact positions based on a signal received from a government or authority (e.g. council, employee or even shopping mall). In other words, the control system may receive a signal transmitted from an authorised non-user (of the transportation device), and control the distance between the contact positions based on this signal. In this way, the transportation device may be required to place the transportation device in a more stable configuration (i.e. space the two ground contacting members apart) in response to an authoritative signal (e.g. when in particular areas and/or at particular times).

In yet other embodiments, the transportation device comprises a device location unit adapted to determine a location of the device (e.g. a GPS unit). Based on the determined location, a distance between the contact positions may be controlled. This may allow, for example, the device to be placed in a more stable configuration when in certain areas (e.g. known pedestrianized areas, shopping malls and so on).

The control system may thereby comprise control logic (e.g. a processor or processing system) adapted to receive signals, including a control parameter, a location, a received signal, a time and so on, and control the movement of at least the first drive 310 so as to control a distance xi between the first contact position 951 and the second contact position 952.

Referring now to Figure 5, in a further embodiment, the control system 300 may be adapted to further comprise a second drive 330 (e.g. mounted in the drive housing 305).

The second drive 330 is adapted to control a movement of a third coupling arrangement 335 with respect to the second drive 330. The second drive may control the movement of the third coupling arrangement in the same manner as previously described with reference to Figures 4A and 4B.

In such an embodiment, the first linking element 321 and the second linking element 322 are adapted to each be rotatably coupled at one end to the third coupling arrangement 335 and at the other end to their respective ground contacting member 100, 101. Movement of the third coupling arrangement 335 with respect to the second drive 330 thereby causes movement of the respective upper portions 192, 193 of the first and second ground contacting members with respect to one another. In other words, as the third coupling arrangement 335 moves, so the distance between the upper portion 192 of the first ground contacting member 100 and the upper portion 193 of the second ground contacting member 101 changes.

Thus, the control system 300 may be adapted to control a distance xi between lower portions of the first and second ground contacting members (i.e. a distance between the first contact position and the second contact position or the track of the transportation device) as well as a distance between the upper portions of the first and second ground contacting members. In this way, a distance between of the first and second ground contacting members along their length may be controlled (by controlling the distance between the upper/lower portions). Furthermore, an angle between the first and second ground contacting members may be readily controlled by controlling the distance between the upper portions relative to a distance between the lower portions (i.e. by altering the ratio between the distance between the upper portions and the distance between the lower portions). Such an embodiment allows for control of the distance between the contact positions and the angle of each ground contacting member with respect to one another independently.

In particular embodiments, the first drive 310 and the second drive 330 are adapted such that the upper portion of each ground contacting member and the lower portions of each ground contacting member are separated at a same rate. That is to say, the orientation of the first ground contacting member (relative to a direction y perpendicular to the ground surface) may be kept substantially the same as an orientation of the second ground contacting member (relative to a direction y perpendicular to the ground surface).

In conceivable embodiments, each ground contacting member 100, 101 is kept substantially perpendicular or normal with respect to the ground surface. Put another way, an orientation of the first ground contacting member 100 with respect to the second ground contacting member 101 may be maintained so as to be substantially parallel to one another, and a distance between the two ground contacting members may be altered using a control system.

Other embodiments of controlling a movement of the ground contacting members (e.g. with respect to one another) will be readily apparent to the person skilled in the art, and may include, by way of example, only, magnetic arrangements, worm drives, gearing systems and so on.

In yet other conceivable embodiments, the transportation device does not comprise a control system adapted to change the distance xl between the first contact position 951 and the second contact position 952. In other words, there may be embodiments in which the distance between the contact positions is not actively changed by a control system or control logic. Rather the distance between the contact positions may or alter due to a natural change in response to a change in a control parameter of the transportation device.

By way of example, with reference to Figure 6, there is proposed an embodiment in which a transportation device 6, comprising a first ground contacting member 600 and a second ground contacting member 601 as previously described. In the present embodiment, the transportation device 6 further comprises a track size adjuster 605.

The track size adjuster 605 comprises a central unit 607 coupled to the first ground contacting member 600 and the second ground contacting member 601 by a respective coupling element 610, 611. That is to say, the track size adjuster 605 comprises a first coupling element 610 fixedly coupled to the first ground contacting member 600 and rotatably coupled to the central unit 607 by a first rotating hinge 620. The track size adjuster 605 also comprises a second coupling element 611 fixedly coupled to the second ground contacting member 601 and rotatably coupled to the central unit 607 by a second rotating hinge 620.

The first coupling element 610 is further coupled to the central unit 607 by a first spring 630 and the second coupling unit 611 is further coupled to the central unit by a second spring 631. In other embodiments, instead of a spring and rotating hinge, the first and second coupling units are coupled to the central unit via a torsion spring (i.e. they are rotatably connected to the central unit via a torsion spring).

The springs 630, 631 provide a force away from the central unit 607, such that the springs attempt to angle the ground contacting members with respect to a direction perpendicular the ground surface (and the central unit 607).

When a speed of the transportation device increases, the ground contacting members 600, 601 move inwardly, against the force of the springs 630, 631, due at least to a precession of the ground contacting members and an angle of the ground contacting members. In other words, as the speed of the transportation device increases, so the angle of the ground contacting members with respect to one another and a direction perpendicular to the ground surface changes. It will be understood that the angle of the wheels may be further considered to change, for example, at least partially due to a gyroscopic effect and/or movement due to the slip angle of the ground contacting members. This may be due to a weight of the user pressing the wheels together, causing the ground contacting member to move inwardly when rotated (due to the slip angle, for example). Thus, as speed and/or distance increases, so the ground contacting members move with respect to one another.

From such an embodiment, it will therefore be apparent that it is not necessary for a transportation device to comprise a control system to control the distance between the contact positions of the ground contacting members, as this may be automatically or naturally performed in response to a control parameter changing over time (e.g. speed, velocity or distance travelled).

Another embodiment of a transportation device 7 may be described with reference to Figure 7, which illustrates the transportation device 7 in a first, stable configuration (A) and a second, manoeuvrable configuration (B). The transportation device 7 comprises a foot support 720 (i.e. load support) and a ground contacting arrangement comprising a first wheel 710 and a second wheel 711 (i.e. a first ground contacting member 710 and a second ground contacting member 711). Each wheel is embodied as a hubless or centreless wheel.

The foot support 720 may be adapted to extend through the open or cut-out area of the hubless or centreless wheels. Put another way, a load support may extend through an empty space or void in the ground contacting member(s). In other words, the foot support 720 may comprise a first foot rest 721 which is extendable through the first wheel 710, and a second foot rest 722 which is extendable through the second wheel 711. A user may place a respective foot on each foot rest 721, 722 as shown in Figure 7.

In other embodiments, the foot support 720 is a load support adapted to support a load (i.e. the load need not be a foot or feet of a user, but may instead be a non-human load such as luggage).

The transportation device 7 comprises a drive arrangement (not shown), for example, a rotor and stator arrangement as previously described or even drive wheels adapted to drive the first wheel and second wheel. Such drive wheels may, for example, be mounted in the foot support).

The wheels may be considered to each have a rotating component and a non-rotating component. The rotating component is adapted to contact the ground surface at a contact position, and is adapted to rotate about the non-rotating component. In embodiments, the nonrotating component comprises a stator and the rotating component comprises a rotor, so as to allow the rotating component to rotate about the non-rotating component. Thus, the first wheel 710 contacts the ground surface at a first contact position 790, and the second wheel contacts the ground surface at a second contact position 791.

The wheels 710, 711 are adapted to rotate about the foot support 720, for example, about at least an axis lying parallel to a fore-aft direction of the transportation device. That is to say, a distance between the contact positions of the wheels is adapted to change by a movement of the lower end of the wheels towards one another. The foot support may therefore be rotatably coupled to the non-rotating component of the wheels, such that the wheels may move with respect to the foot support.

In other words, the transportation device is configurable to be in a first configuration A, in which the contact positions of the wheels are spaced apart, and in a second configuration B, in which the contact positions of the wheels are proximate to one another.

When in configuration A, the transportation device may be considered to be analogous to an “A-shape”, when in configuration B, the transportation device may be considered to be analogous to an “I-shape”. That is to say, in configuration A, the transportation device resembles the letter A, whereas when in configuration B, the transportation device more closely resembles the letter I.

Thus, if we consider a first axis of rotation, representing the axis about which the first wheel rotates, and a second axis of rotation, representing the axis about which the second wheel rotates, an angle between these axes may be changed. When in the first configuration A, the axes are not parallel with one another, and when in the second configuration B, the axes are parallel with one another.

When in configuration A, the foot rests 721, 722 are both positioned between the contact positions 790, 791. This provides an extremely stable platform for a user, for example, to mount and dismount from the transportation device, improving an ease and safety of mounting the device. When in configuration B, the foot rests 721, 722 are both positioned to lie either side of the contact positions 790,791 (i.e. they lie either side of the wheels 710,711). In such a configuration, the transportation device resembles a self-balancing electric unicycle, and may have increased ease of manoeuvrability and improved agility when the device is moving at speed. Such an above-described embodiment is preferable, but embodiments are not limited thereto. For example, in some embodiments, the foot rests may always lie either side of the contact positions (i.e. they may not lie between the ground contacting members in any configuration).

To enable the first wheel and the second wheel to be angled with respect to one another, with reference now to Figures 8, 9A and 9B, the first wheel 710 and the second wheel 711 may be coupled together via a hinging mechanism 800. The hinging mechanism comprises a first hinging element 810 adapted to rotatably or pivotably couple a second hinging element 820 to a third hinging element 830. The second hinging element 820 rotatably couples the first hinging element 810 to the first wheel 710 and the third hinging element 830 rotatably couples the first hinging element 810 to the second wheel 711.

In other words, the hinging mechanism 800 is formed from three hinges connected in series, the hinging mechanism connecting the non-rotating component of the first wheel 710 to the non-rotating component of the second wheel 711. A middle hinge (first hinging element 810) is arranged to be substantially perpendicular to the two outer hinges (second hinging element 820 and third hinging element 830). In other words, an axis about which the first hinging element hinges is substantially perpendicular to the axes about which the second and third hinging elements hinge. Preferably, an axis about which the second hinging element hinges is substantially parallel to an axis about which the third hinging element hinges.

As will be understood in the common parlance, a hinging element may be thought to comprise of at least three components: a first leaf; a second leaf and a pin, wherein the first and second leaf are each adapted to rotate around the pin. Thus, the position of the pin defines the axis about which a hinging element hinges. In this way, the first and second leaf may rotate with respect to one another. It will be understood that leaves of the hinging elements may be shared between hinging elements. In the present embodiment, a first leaf of the first hinging element is also the first leaf of the second hinging element, and a second leaf of the first hinging element is also the first leaf of the third hinging element.

For the sake of clarity, the axes about which each respective hinging element hinges is shown in Figures 8, 9A and 9B, indicated by the crosshairs. Thus, the crosshairs are indicative of a position of a pin of a hinging element.

The hinging mechanism 800 (and the second and third hinging element in particular) permits the wheels 710, 711 to be angled with respect to one another (and with respect to a direction perpendicular to the ground surface). The angle of the wheels with respect to each other should be understood to mean the angle of the comer of the two wheels marked or identified by the hinging mechanism. It will therefore be understood that a large angle implies that the contact positions of the first and second wheels are distantly spaced, whereas a small angle implies that the contact positions of the first and second wheels are proximate to one another.

Alternatively, it could be interpreted that the angle of the wheels is the inverse of the angle between the respective axes of rotation of each wheel. It will be apparent that distantly spacing contact positions implies that there is a smaller angle between respective axes of rotation of each wheel, whereas proximately spaced contact positions implies a larger angle between respective axes of rotation.

In particular, it is noted that the first hinging element 810 allows the first wheel 710 and the second wheel 711 to be positioned about an axis perpendicular to a ground surface. In other words, the first hinging element allows the first and second wheel to be angled with respect to a forward and rearward (i.e. fore-and-aft) direction of the transportation device.

The second 820 and third 830 hinging elements allow the first wheel and the second wheel to be positioned with respect to a vertical direction, being a direction perpendicular or orthogonal to the ground surface (direction y).

Thus, we may consider the angle between the leaves of the first hinging element as representative of the angle of the wheels with respect to a forward and backward (i.e. fore-and-aft) direction of the transportation device. Similarly, we may consider the angle between the leaves of the second hinging element and the angle between the leaves of the third hinging element as representative of the angle of the wheels 710,711 with respect to a vertical direction (i.e. perpendicular to the ground surface). By way of example, as the angle between the leaves of the second hinging element changes, so the angle of the first wheel with respect to a vertical direction y changes. The sum of the angle between the leaves of the second hinging element and the angle between the leaves of the third hinging element may be representative of the angle between the first and second wheel.

The above described hinging element further causes, when the first hinging element is closed, an angle of the wheels to move from an initial angle ai (as shown in configuration A of Figure 8) to a smaller angle as the wheels begin to rotate, due to at least a natural precession effect. Put another way, as both wheels point inwardly (and are able to be angled with respect to one another) - as the wheels move forward, the contact positions are drawn closer together so as to be more proximate to one another. This causes the angle between the wheels to be reduced, and the second and third hinging elements to close. In other words, as initially angled wheels begin to move, the angle between the wheels decreases due at least to a natural precession effect.

Such an embodiment will allow a user to have an increased stability when mounting the device (as the contact positions may be spaced apart). However, the user will still maintain a good or more intuitive manoeuvrability when moving at speed (i.e. when the wheels have been brought together), as the contact positions will be proximate to one another, analogous to a single-wheeled device.

An embodiment will now be described in which the angle of the wheels (e.g. with respect to a direction perpendicular to a ground surface) may be increased (as opposed to merely reducing), with specific reference to Figures 9A and 9B, which both depict a bird’s-eye view (i.e. viewed along the direction y) of the first hinging element, in different configurations, when viewed from the cross section bi-b2.

In Figures 9A and 9B, the transportation device comprises an actuating element 900, adapted to control the hinging action of the first hinging element 810. In other words, the extent to which the first hinging element is opened and closed may be controlled by an actuating element. The actuating element may, for example, comprise a worm drive or preferably a magnet 910 and corresponding solenoid 911 (coupled to either leaf of the hinging element). In such a latter embodiment, control of the current passing through the solenoid controls an attractive force between the solenoid and the magnet, and thereby the opening and closing of the first hinging element.

To cause the angle ai between the wheels to be increased, the first hinging element is moved from a closed configuration (Figure 9A) to an open configuration (Figure 9B) by the actuating element 900. This causes the first 710 and second 711 wheel to be angled with respect to a forwards and backwards direction (i.e. fore-and-aft) of the device, whilst maintaining a same distance between the contact positions of the wheels. As the wheels continue to turn (i.e. the device moves forward), the wheels move apart from one another (due to the angle of the wheels) and become angled with respect to one another and a direction y perpendicular to a ground surface. Put another way, it will be apparent that the distance or spacing between the contact positions increases as the device continues to move forward.

This process can be more readily understood with reference to Figure 9C, which depicts the transportation device 7 in a variety of configurations. Views I, Π and III illustrate the transportation device 7 in a respective three different configurations when viewed from a rearward to a forward direction (i.e. viewed along a z-axis). View IV, V and VI illustrate the transportation device 7 in the same three different configurations when viewed from a top down view (i.e. viewed along a y-axis).

Put another way, Views I and IV show the transportation device 7 in a same configuration from different perspectives. Views II and V also show the transportation device 7 in a same configuration (different to that of Views I and IV) from different perspectives. Views ΠΙ and VI also show the transportation device 7 in a same configuration (different to that of Views I, II, IV and V) from different perspectives.

Initially, the device may be in a first configuration (Views I and IV), in which the wheels are substantially parallel to one another, and are not angled with respect to a direction perpendicular to a ground surface (direction y) or in a direction perpendicular to a forward and backward direction (direction z). Thus, as the transportation device 7 moves forward, the wheels attempt to move in a same forward direction (i.e. direction z). The first hinging element 810, the second hinging element 820 and the third hinging element 830 are all in in a respective closed configuration.

As the first hinging element 810 moves to an open configuration (Views II and V), for example due to the actuating element 900), the wheels 710, 711 become angled with respect to a direction parallel to a forward and backward direction (direction z). However, the wheels remain non-angled with respect to a direction perpendicular to the ground surface (direction y)·

Due in part to the fact that the wheels are directed away from one another - as the wheels continue to rotate (i.e. the transportation device moves forward in a z direction), the distance between the contact positions of the wheels begins to increase such that they attempt to move in different directions. Put another way, both wheels attempt to move in a direction angled with respect to direction z. However, it is noted that the resultant movement of the transportation device typically remains generally in the direction z. This causes the wheels to become angled with respect to one another (as the two wheels remain coupled by the hinging mechanism 800, such that outward movement of the wheels causes the wheels to become angled) and with respect to a direction perpendicular to a ground surface (View III and VI). In other words, the second 820 and third hinging elements 830 automatically move from a closed configuration to an open configuration.

The herein presented embodiment of a hinging mechanism 800 thereby allows for alteration of an angle of the first wheel 710 and an angle of the second wheel 711 with respect to a vertical direction (i.e. perpendicular to the ground) and with respect to a forward and backward direction (i.e. a fore-aft direction or a direction of travel).

The actuating element 900 is preferably adapted to control the first hinging element based on a control parameter of the transportation device. Preferably, the control parameter is either a speed (i.e. at low speed, the actuating element 900 opens the first hinging element 810) or an acceleration (e.g. when a deceleration is detected, the actuating element opens the hinge). Other control parameters on which the control of the first hinging element may be based will be readily apparent to the person skilled in the art.

Such a proposed embodiment allows for a simple and readily implementable method of controlling the distance and angle between the two ground contacting members.

In one embodiment, the actuating element is adapted to maintain the first hinging element 810 a predetermined distance apart when the device is in motion (i.e. keep the first hinging element 810 open). In this way, the actuating element 900 may maintain the ground contacting members a predetermined distance apart and counteract the precession effect caused by the angled wheels, which attempts to bring the wheels closer together. Thus, the distance between the first and second hinging element may be maintained. Preferably, the actuating element 900 maintains the ground contacting members such that (in motion) they are substantially parallel to the one another, and perpendicular to a ground surface.

It will be clear that the hinging mechanism 800 and the actuating element 900 may together be considered as a control system of the transportation device 7.

In some embodiments, there may be provided further actuating elements adapted to control the hinging of the second and/or third hinging elements. In this way, an angle of the first and second wheels with respect to a vertical direction of the transportation device may be actively controlled. This may be particularly advantageous to ensure a high accuracy and consistency of movement of the first and second wheels.

In some embodiments, the actuating element may be adapted to be maintained in the open configuration (Figure 9B) when the device is rotating, this will cause the wheels to remain angled with respect to one another and thereby maintain a spacing or distance between the wheels (i.e. maintain the device in configuration A as shown in Figure 7).

In preferable embodiments, the distance between the contact positions of the ground contacting members 710, 711 is adjustable up to a maximum distance of more than 25cm (250mm). This would allow (e.g. at a maximum separation) the contact positions to lie outside of the position of a user’s foot (when the user is supported by the load support 720). This advantageously provides a high amount of stability for a user, for example, when mounting the device.

Preferably, the minimum distance between the ground contacting members is equal to the width of a ground contacting member (assuming both ground contacting members are the same). In other words, in preferable embodiments, the first ground contacting member is positionable to lie directly alongside (e.g. in contact with) the second ground contacting member. It will be apparent that in preferable embodiments, the ground contacting members are substantially the same.

Although above described embodiments describe a hinging mechanism comprising three hinging elements, it will be readily apparent to the person skilled in the art that the hinging mechanism may instead comprise any number of hinging elements. For example, the hinging mechanism may comprise a single hinging element adapted to rotatably couple the first wheel 710 to the second wheel 711.

With reference to Figure 10A, in an embodiment a transportation device 1000 comprises a handle 1010. The handle 1010 may be adapted to connect around an outside of the ground contacting arrangement such that the ground contacting members may lie substantially alongside one another when the transportation device in in a closed configuration.

The transportation device 1000 may comprise at least one load support 1020 adapted to be positioned in an open configuration (in which it can support a load) and a closed configuration (in which it cannot support a load). In other words, the load support 1020 may be adapted to rotate with respect to the transportation device so as to selectably support a load (e.g. a user) thereon.

In further embodiments, the angle of the load support(s) 1020 with respect to the ground contacting member may be adjusted in response to an angle of the ground contacting member with respect to a ground surface changing. By way of example, the load support may adjust so as to remain substantially horizontal to a ground surface, for example, in response to the angle of the ground contacting member adjusting with respect to the ground surface. It will be apparent that the angle of the ground contacting member may adjust due either to a leaning of the device (in performing a turn) or as the distance between the contact positions changing.

In another embodiment, shown in Figure 10B, there is provided a transportation device 1050 having a handle 1060 which passes or lies between the first ground contacting member 1070 and the second ground contacting member 1080 of the ground contacting arrangement. In such an embodiment, when the contact positions of the wheels are proximate to one another, the ground contacting members may be angled with respect to a vertical direction (i.e. a direction y). In other words, the ground contacting arrangement may resemble a ‘V-shaped’ device, where upper portions of the ground contacting members are spaced further apart than lower portions of the ground contacting members.

Figure 11 shows further configurations of the transportation device 1100 according to at least one embodiment.

In particular, there is a configuration C in which the transportation device 1100 is configured to resemble a “V-shape” (i.e. a letter V). In such an embodiment, the contact positions 1151,1152 of the ground contacting members are proximate to one another, but upper portions 1192, 1193 of the ground contacting members are spaced apart from one another. Put another way, the ground contacting members are angled with respect to a direction perpendicular to the ground surface, with the contact positions of the ground contacting members being proximate to one another. Angling wheels in this manner may improve an agility of the transportation device.

There may also be considered a configuration D, in which the transportation device 1100 is configured to resemble a letter H (i.e. “H-shaped”). In such an embodiment, the contact positions of the ground contacting members are spaced apart from one another, and the wheels are substantially parallel to one another. Thus, upper portions of the ground contacting members and lower portions of the ground contacting members are both spaced apart.

In such above embodiments, the transportation device may not (for example) comprise a hinging mechanism, but may rather comprise the control system as described with reference to Figures 3 to 5. Other embodiments of suitable control system would be readily apparent to the skilled person.

In the above described configurations (C and D), a user standing on the load support 1120 may stand with their feet between the first ground contacting member and the second ground contacting member. This may allow for improved ease of manoeuvring the transportation device, as a user’s feet would be closer to the centre of gravity of the transportation device (such that the transportation device is less sensitive to minor shifts of the user’s weight for example).

In embodiments, the ground contacting arrangement of the transportation device is configurable between any above described configuration (e.g. configuration A or B, Figure 7, or configuration C or D, Figure 11). In other embodiments, the ground contacting arrangement of the transportation device is only configurable between selected configurations. By way of example, the transportation device may be configured so as to only be configurable between configuration C and D (of Figure 11), or to only be configurable between configuration A and B of Figure 7.

An understanding of yet further embodiments of a control system for controlling the distance between the first ground contacting members and the second ground contact member may be elucidated with reference to at least Figure 12A- 12D. Each of these identified control systems is adapted to be positioned above the ground contacting arrangement (i.e. not positioned between the first and the second ground contacting members).

With reference to Figure 12A and 12B, in a particular embodiment a control system 1200 comprises a drive 1210 adapted to control the position of a coupling element 1220 relative to the drive 1210. This may be in a same manner as previously described, such that the drive 1210 is adapted to control the rotation of a screw, so as to control the position of the coupling element 1220 with respect to the drive 1210.

The coupling element 1220 is coupled to a linking arrangement 1230, which connects to the upper portions of the ground contacting members 100, 101 of the transportation device. Movement of the coupling arrangement 1220 (i.e. by the drive 1210) causes a change in the configuration of the linking arrangement 1230, so as to control the angle between the first ground contacting member 100 and the second ground contacting member 101.

Figure 12A identifies the linking arrangement in a first configuration, such that the ground contacting element are substantially perpendicular with respect to a ground surface. Figure 12B illustrates the linking arrangement in a second configuration, such that the ground contacting members are angled with respect to the ground surface.

The linking arrangement 1230 comprises a first hinging rod 1231 and a second hinging rod 1232 adapted to couple the coupling element 1220 to a respective ground contacting member. Each hinging rod 1231 comprises a first 1233 and second 1234 portion hinged or rotatably coupled together, the first portion 1233 coupling to the coupling element 1220 and the second portion 1234 coupling to the ground contacting member 100. The angle of the second portion 1234 (i.e. relative to a direction orthogonal to a ground surface) defines an angle of the ground contacting member relative to the ground surface.

It will be apparent that as the coupling element 1220 moves relative to the drive 1210, so the angle of the first portion relative to the second portion changes. Furthermore, as the coupling element 1220 moves relative to the drive 1210, so the angle of the first portion 1233 and the second portion 1234 relative to a direction perpendicular to a ground surface changes.

In this way, movement of the coupling member 1220 causes an angle of the ground contacting members 100, 101 (relative to the ground surface) to change. Thus, movement of the coupling member 1210 (causing by the first drive 1210) causes a distance between contact positions of the ground contacting members 100, 101 to be altered.

The linking arrangement 1230 may further comprise a support rod 1236 rotatably coupled to the first 1231 and second 1232 hinging rod, in particular, rotatably coupled to the second portion of each of the first and second hinging rod at a connecting position 1235. It will be apparent that the connecting position 1235 is part way along the second portion 1234 of the hinging rod 1231. Put another way, the support rod may brace the first 1231 and second 1232 hinging elements apart.

The support rod 1236 maintains the respective connecting positions of the first 1231 and second 1232 hinging rod at a same distance apart. This allows for a greater degree of control over the angle of the ground contacting members with respect to a ground surface. Furthermore, this helps ensure that the angle of the ground contacting members is defined by the position of the coupling element 1220 with respect to the drive 1210.

As the support rod 1236 is rotatably connected to both hinging rods 1231, 1232, it will be apparent that the linking arrangement 1230 may act as a suspension-like arrangement, allowing the ground contacting members 100, 101 to be displaced with respect to the ground surface (whilst maintaining a same angle with respect to the ground surface).

In another (more compact) embodiment, such as that shown in Figures 12C and 12D, the drive 1210 may be formed as an aspect of the support rod 1236, such that the first hinging rod 1231 and the second hinging rod 1232 are rotatably coupled to the connecting member 1210, the drive 1210 and a respective ground contacting member 100. It is noted that Figure 12D illustrates a side view of the embodiment shown in Figure 12, when viewed from the line ki-k2.

In order to perform the movement of the connecting member 1220 with respect to the drive 1210, the drive 1210 may instead control the position of a first 1241 and second 1242 movement member. Each movement member 1241, 1242 is rotatably coupled to a first end of a respective movement rod 1243, which is in turn rotatably coupled at the other end to the connecting member 1220. By moving the movement member(s), so the position of the connecting member 1220 may be controlled.

This may allow for a more precise control of the movement of the connecting member 1220 with respect to the drive, so as to more accurately and precisely control the angle of the first and second ground contacting members with respect to the ground surface.

In other or further embodiments, the ground contacting arrangement comprises more than two ground contacting members, for example, three ground contacting members that may be separated from one another or angled with respect to one another. The provision of additional ground contacting members will improve the stability provided to the device. It will be understood that in preferable embodiments, each ground contacting member is positioned to lie in a same axis, although embodiments are not limited thereto.

In at least one conceivable embodiment, each ground contacting member forms a part of a single wheel. That is to say, a single wheel may be divided into two or more ground contacting members, each ground contacting member being associated with a respective contact position.

By way of example, there may be provided a single wheel formed from an expandable hub, having two or more tyres mounted thereon (each tyre representing a respective ground contacting member). It will be apparent that each tyre is adapted to contact the ground surface at a respective contact position. A size of the expandable hub may be altered so as to alter the difference between the two or more tyres, based on at least a control parameter of the transportation device.

In this way, the distance between the contact positions may alter and/or be controlled based on at least a control parameter of the transportation device.

In other examples, each of the first and second ground contacting members comprise a tyre shaped as a half-tyre profile, such that when the first and second ground contacting members are positioned next to each other, they resemble a single tyre. This may be of particular advantage to ensure a high manoeuvrability device (i.e. to be analogous to a device having only a single tyre, such as a self-balancing unicycle).

Although above embodiments may describe scenarios in which the position of the first ground contacting member and the second ground contacting member may be individually controlled, it will also be apparent that in other conceivable embodiments, only the movement or angle of a single ground contacting member is controlled. In such embodiments, for example, only the movement of the first ground contacting member is controlled, whilst the position of the second ground contacting member remains substantially stationary.

Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit may fulfil the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. A self-balancing powered transportation device, comprising: a ground contacting arrangement comprising: a first ground contacting member adapted to contact a ground surface at a first contact position; and a second ground contacting member adapted to contact the ground surface at a second contact position; a load support adapted to support a load; a drive arrangement adapted to drive at least one of the ground contacting members; and a balance control system adapted to maintain a fore-aft balance of the self-balancing powered transportation device, wherein the transportation device is operable in at least: a first configuration, in which the first contact position and the second contact position are spaced a first distance apart; and a second configuration, in which the first contact position and the second contact position are spaced a second, different distance apart.

2. The self-balancing powered transportation device of claim 1, wherein a distance between the first contact position and the second contact position is adjustable based on a control parameter.

3. The self-balancing powered transportation device of claim 2, wherein the control parameter comprises at least one of the following: a speed of the transportation device; an acceleration of the transportation device; a distance travelled by the transportation device; a time since power on of the transportation device; an average speed of the transportation device; a fore-aft balance of the transportation device; a fore-aft balance of at least one ground contacting member of the transportation device; an amount of desired yaw rotation of the transportation device; and a torque applied by the drive arrangement.

4. The self-balancing powered transportation device of any preceding claim, further comprising a control system adapted to control the distance between the first contact position and the second contact position.

5. The self-balancing powered transportation device of any preceding claim, wherein an axis of rotation of the first ground contacting member and an axis of rotation of the second ground contacting member is adjustable, so as to perform at least one of the following: adjust the distance between the first contact position and the second contact position; adjust an angle of the first ground contacting member and the second ground contacting member with respect to a ground surface; adjust an angle of the first ground contacting member and the second ground contacting member with respect to one another; adjust an angle of the first ground contacting member and the second ground contacting member with respect to a direction of travel; and adjust an angle of the first ground contacting member and the second ground contacting member with respect to a direction perpendicular to the ground surface.

6. The self-balancing powered transportation device of any preceding claim, wherein moving the first ground contacting member with respect to the second ground contacting member angles the first ground contacting member with respect to the second ground contacting member.

7. The self-balancing powered transportation device of any preceding claim, further comprising a hinging mechanism adapted to pivotably couple the first ground contacting member and the second ground contacting member.

8. The self-balancing transportation device of any preceding claim, wherein: at a first speed of the transportation device, the first ground contacting member and the second ground contacting member are angled with respect to one another; and at a second speed of the transportation device, the first ground contacting member and the second ground contacting member lie substantially parallel to one another.

9. The self-balancing powered transportation device of claim 8, wherein the first speed is less than the second speed.

10. The self-balancing powered transportation device of any of claims 1 -4, wherein: the first ground contacting member and the second ground contacting member are substantially parallel with one another; and a distance between the first ground contacting member and the second ground contacting member is adjustable so as to adjust the spacing between the first contact position and the second contact position.

11. The self-balancing powered transportation device of any preceding claims, wherein the distance between the first contact position and the second contact position is adjustable between Omm and 2000mm.

12. The self-balancing powered transportation device of any preceding claim, wherein the distance between the first contact position and the second contact position is adjustable in response to a user input.

13. The self-balancing powered transportation device of any preceding claim, further comprising a control parameter detection unit adapted to detect a control parameter of the unicycle device.

14. The self-balancing powered transportation device of any preceding claim, wherein the load supports are adapted to extend through an empty space of the ground contacting members.

15. A self-balancing powered transportation device substantially as herein described with reference to the accompanying figures.