Patent Application
20240342588
The present invention relates to virtual reality (VR) footwear, that is, a shoe-like device which counteracts the walking movements of a person wearing the VR footwear, thereby allowing the wearer to move around in VR environments whilst the wearer actually remains in the same physical or real-life location, or within a predefined area.
VR systems (sometimes called augmented reality systems) generally generate a three-dimensional virtual environment, using devices such as goggles, helmets including a display, gloves fitted with sensors, screens, sound systems and the like. The devices contain sensors, data processors and communications devices to communicate with an external computing device which tracks the movements made by and inputs made to the devices, processes this data to make appropriate changes in the VR environment and outputs the associated data to the devices so that the devices can respond appropriately (for example by displaying a changed view in goggles, or by delivering a haptic response to be felt by or a sound to be heard by the user). When the user is immersed in the VR environment, the various devices allow interaction with that environment and virtual objects within that environment, and the wearer to move around in the virtual environment. VR systems exist within the physical, or real-life world, and so have physical boundaries and/or physical objects and features which could limit and/or impede the user's movement should movement in the virtual environment bring the wearer into contact with a physical limit, object or feature. A person wearing goggles which display a VR environment is usually blind to the physical environment, and there is therefore a risk that if the person's real-life movements across the ground are communicated to the system so as to replicate that movement in the virtual environment, the person could trip or bump into objects in the real world.
VR footwear has therefore been developed which counteract the walking or other movements over the ground of a person wearing the VR footwear, so enabling the wearer to stay in one safe spot, or within a safe area, while enjoying apparent motion in the VR environment during a VR game or other experience. One such apparatus is disclosed in US 2018/0326286; another has been designed by the private company Ekto VR, of Pittsburgh USA (see www.ektovr.com). Both of these start from the concept of a “powered roller skate” such as in US 2014/0262576 or U.S. Pat. No. 6,059,062, in which powered footwear is used to transport a person wearing the footwear and essentially reverse it to apply the concept to the VR environment. Position sensors, gyroscopes, processors and computing devices and communications devices in the footwear work in combination with the external computing device of the VR system and the locomotory features of powered roller skates (motors, wheels, belts, etc.) to sense the mechanical walking action of the person wearing the footwear and to counteract or negate it, so that although the person carries out the real-life actions of walking, running, jumping, etc. those actions are rendered ineffective and the person remains in the same physical position or area. Thus the wearer of such footwear in these systems will expend physical effort as if moving, while the actions taken by the systems to keep the person in the same physical location can be sensed and utilised by the system so as to transfer the person's real-life movements and replicate them in the VR environment. Both of the known systems accommodate the natural flexure of the foot during normal walking motion, and they can be arranged so as to minimise motion sickness. The present invention is a development of these known concepts.
One problem with known VR footwear is that it is inefficient at dealing with physical movement of the wearer's feet in anything other than the straight ahead or longitudinal direction; people do not only walk with their feet exactly longitudinally, they sidestep and the flexibility of the ankle joint allows the foot to swivel and the person to walk at an angle sideways, transversely, in a rearwards direction or in curved paths, and conventional VR footwear is not good at rapidly accommodating these non-longitudinal or turning movements. Another problem is that they can be excessively tall, so that the wearer feels as if they are walking on high, platform soled shoes; this makes for an unnatural “feel” to the wearer, is uncomfortable, affects the ability of the wearer to balance properly and risks the wearer tripping and falling. They are also often heavy, bulky, mechanically complicated and expensive to manufacture. The footwear disclosed in US 2018/0326286 appears to be able only to compensate for walking in a forwards/rearwards direction in a VR environment, and does not describe or explain how the footwear might compensate for sideways steps (despite referring to a “return zone”, which is illustrated as a circle on the ground). The Ekto VR system appears to compensate for sideways movement as well as forward/rearward movement, and achieves this by having multiple powered caster wheels; however, this results in footwear which is tall, heavy, and significantly broader than the human foot, and such broad footwear is difficult to walk in until sufficiently acclimatised to the breadth.
To explain some of the directional terminology as used herein we refer to the anatomy of a human, which may be defined by three orthogonal planes:
The terms “forward”, “front”, “back” and “rear” and like or related terms used herein should generally be interpreted in relation to the sagittal plane of the user of the footwear, terms such as “left”, “right”, “transverse” and like or related terms used herein should be interpreted in relation to the coronal plane of the wearer of the footwear, and terms such as “up”, “down”, “above”, “below” and like or related terms used herein should be interpreted in relation to the horizontal plane of the wearer of the footwear. It should also be noted that, although when walking a person's feet are usually aligned with the body and operate in the longitudinal plane, the ankle joint also allows the foot to rotate about the lower leg so that the foot is no longer aligned longitudinally relative to the user's; in this case the directional terms should be construed as relating to the foot of the wearer and to the footwear itself—and in particular to the parts of the footwear which are in close contact with the wearer's foot.
The present invention is predicated on the realisation that an existing means of propulsion addresses many of the problems of conventional VR footwear and provides additional advantages.
The present invention therefore provides a footwear assembly for use in a virtual reality environment comprising a front platform portion having an upper surface adapted and configured for supporting and releasably retaining the forward part of a user's foot and a rear platform portion having an upper surface adapted and configured for supporting and releasably retaining a rear part of the user's foot, the front and rear platform portions being joined by a transverse hinge so that the platform portions can pivot relative to one another in the longitudinal plane to accommodate flexing of the user's foot as this occurs in walking, in which each platform portion has mounted to a lower surface thereof at least one drive motor, each drive motor driving a continuous belt, and two continuous belts on each platform portion being arranged substantially in parallel, one located to each side of the platform portion, and in which the drive motor or motors and continuous belts of the front platform portion are mounted to a front drive module and the drive motor or motors and continuous belts of the rear platform portion are mounted to a rear drive module, the drive modules being mounted beneath their respective platform portions so each drive module may rotate in the horizontal plane relative to the platform portion it is mounted beneath.
With such an arrangement there are two separate continuous belts on each side of the assembly, arranged front-to-rear, the continuous belts operating in the same way as do caterpillar tracks or tank tracks, and which can allow a degree of turning in the same manner as do caterpillar tracks, but the relatively short length of each “track” (in use, the length of the front and rear platform portions together is preferably approximately the same as that of a large human foot with each “track” being no more than about half the length of a foot) allows this to a greater extent than could a system which uses belts of the same length as a foot (such as the system in US 2018/0326286).
There may be two motors in each drive module, each motor driving one continuous belt; the use of four driven continuous belts beneath a user's foot means that the driving forces for the compensatory movements as the user walks wearing the assembly can be split between four motors (two in each module), which allows the motors to be smaller than if there were only a single motor per module and also, if the motors are independently controlled, allows the assembly better to adapt to and compensate for variations in distribution of bodyweight along and across the foot during both normal walking in a forward direction and also in sidestepping, sideways or turning movements. Independent control of the motors also facilitates a reduction in motion sickness inducing effects, as will be described below. Finally, such an arrangement permits a very compact and low-height assembly, as will be seen in the embodiment described below. The hinge, as in US 2018/0326286, allows for the normal flexing of the user's foot (at the ball of the foot, between the toes and the heel) when walking in a forward direction. The word “substantially” is used deliberately above, to accommodate the fact that, as in caterpillar tracks, when the belts are used to compensate for turning or lateral movements, this can be assisted by allowing a certain amount of temporary flexing and/or transverse movement of a belt along its length during which the two belts are temporarily not aligned in parallel. It will be understood that there could be only one motor to drive both continuous belts in a module, and also that the footwear assembly could easily be configured to be used by a user with or without outer footwear, and the word “foot” used herein should be construed accordingly.
Allowing the drive modules to rotate relative to the platforms and the foot the platforms support improves the maneuverability of the assembly and hence its ability to compensate for a broad range of possible foot movements by the user/wearer of the assembly, including sidesteps, steps at an angle to the forward direction, and steps in which the direction of the foot changes mid-step (i.e. turning).
Preferably there is a front turn motor adapted to selectively rotate the front drive module relative to the front platform portion and a rear turn motor adapted to selectively rotate the rear drive module relative to the rear platform portion. The turn motors may be adapted to drive the two drive modules to rotate so that they remain aligned and parallel as they rotate, or so that they rotate in the same direction but at different rates, or so that they rotate in different directions and/or at different rates; this allows for maximum adaptability to the range of possible movements a user may make, whilst being controllable so as to minimise potential motion sickness effects. The rotational movement of the drive modules may be constrained to a maximum of 90° in either direction from the longitudinal plane; this is advantageous because it means that power and control can be easily achieved by wires/cables without fear of tangling or catching, and the turn motors only need to turn each drive module through a total of 180°. The drive motors could be operable in two directions so as to effectively provide for 360° of movement of the drive modules. The turn motors may be stepper motors or they could be geared DC motors (otherwise known as servos), with either being coupled to a position sensor; these are easily adapted, through suitable gear movements, to provide a controlled degree of indexed rotary movement, whilst supporting a person's bodyweight, the index movement permitting straightforward calculation of the compensatory effect each step would have on the actual movement of the user's foot.
The continuous belts may be of the same length, and the motors may be located within a continuous belt. The motors may drive a continuous belt either directly, by acting on one of two pulley wheels between which the continuous belt stretches, or indirectly by way of a motor which drives a primary belt which engages with one of the two pulley wheels; the primary belt is preferably smaller (in width and length) than the continuous belts. Providing equal length belts gives improved weight and load capability, and increases the lifespan of the apparatus, it also simplifies the design and reduces the number of different consumable components needed for long term maintenance of the apparatus. Preferably, when the continuous belts are of equal length, the motors drive the primary belt via a splined wheel which is coaxial with the motor, so that the motor and the associated primary belt can be located on opposite sides of the drive module so that they can fit within the continuous belts. Locating the motors inside the belts protects them from damage, as does locating the primary belt within the continuous belt, and locating the motor and the splined wheel on opposite sides of the drive module helps distribute and/or equalise the forces exerted on the apparatus in use whilst enabling an overall compact size and configuration.
The continuous belts on each module may be of different lengths. This may be thought to be an undesirable or unnecessary feature, because it suggests that the belts on opposite sides of each module have different surface areas in contact with the ground surface and therefore less grip/traction to transmit the driving motion; however, the actual contact area that matters is the part of the belt immediately underneath the drive wheels and drive pulleys, because these press the belt beneath them against the ground surface. The middle part of each belt between the drive wheels does not contribute significantly to the traction/grip because it is not pressed as firmly against the ground surface as that sandwiched between the ground and the drive wheels/pulleys. Having one belt longer than its pair on the other side of the module also allows the motors to extend fully across the module (from one side of the module to the other side of the module), but for the motor of the shorter belt to be located within longer belt, which permits the overall design to be very compact in the horizontal plane, not substantially more than a large footprint, and not excessively tall.
The shorter continuous track under the front platform portion may be aligned longitudinally on the same side of the front platform portion as the longer continuous belts under the rear platform portion, and vice versa. This ensures that, in forward walking at least, differences between bodyweight support and frictional engagement by the different length belts can be evened out transversely; this may be assisted by giving the longer belt a surface having a greater friction coefficient than the shorter belt.
Each continuous belt may extend between at least one drive wheel having axial ribs and at least one pulley wheel having axial ribs, an inner surface of each continuous belt may have transverse ribs which are complementary to the ribs on the drive wheel and pulley wheel, and the inner surface of the continuous belt may have a rib extending longitudinally over substantially the entire inner surface of the belt. Such an arrangement can be used to limit the amount of transverse movement of the belts relative to the drive/pulley wheels and prevent the belt disengaging therefrom. Circumferential channels can be provided in the drive wheel and the pulley wheel, the longitudinal rib being located and configured so as to fit within these channels, so that the belt is retained against transverse disengagement. Additionally or alternatively the or each drive wheel and/or the or each pulley wheel is formed of a pair of separate, axially-spaced ribbed wheels, the axial spacing of the or each pair of wheels providing the same effect as the circumferential channels described above. Preferably the transverse size of the longitudinal rib is less than the axial size of the circumferential channels; this allows some lateral movement of the belt (which is good for turning) but limits it (which reduces the risk of the belt disengaging).
Preferably the drive motors are brushless DC electric motors. These are compact, reliable, and capable of providing high torques suitable for applying the forces and speeds/accelerations which are required to compensate for the movements of a person (up to about 100 kg, say) in a manner which reduces the risk of motion sickness.
A system for use in a virtual reality environment may comprise a pair of footwear assemblies described above, with each footwear assembly comprising a transmitter/receiver for transferring data between assemblies and/or between the assemblies and an external VR environment computer. Each assembly would have its own power supply, located either behind the wearer's heel (as in US 2018/0326286) or within one or both of the modules of each assembly and/or within the chassis to which the modules are mounted. There may be a processor in the external VR environment computer for handling and manipulating the data, and/or processors may be provided in each footwear assembly for distributing these functions.
The system may be adapted to calculate a correction vector representing the distance and direction between the actual coordinate of the centre of the user's body and the origin (starting position) coordinate at least once for every stride (or single step) made by each foot. The system may be adapted to utilise the correction vector and the actual heading of each VR footwear assembly to calculate a rotation angle of each drive module and to adjust the speed of the drive motors (faster or slower than user's actual walking speed) in order to gradually return the user to the user's original starting position. The system may be adapted to combine positional data from both footwear assemblies to determine their heading/direction relative to the user's body (torso), and to use this heading for direction control within the VR environment and/or for positional correction. This is advantageous because no additional electronics and sensors need be attached to the user's body, thereby reducing cost and complexity.
The invention will now be described by way of example and with reference to the accompanying figures, in which;
b and 6c are perspective views of the front end of the footwear assembly of
The present invention is concerned with products for Virtual Reality (VR) that aim to solve one of the biggest problems with current technology: that is natural and unrestricted ‘Walking in VR’. Generally, these products are known as VR locomotion systems. Current VR technology limits the user to the confines of a small ‘clear area’ within their homes, usually a living-room or office. The user can take a few steps but will soon reach the boundary of their play area, this is often described as ‘immersion breaking’ and is an annoyance to the user in what is otherwise a great experience. The challenge is to create a technological solution that can allow a user to walk normally, as well as stopping, turning etc, but prevent the user from physically moving outside a small area (˜1.1×1.1 m). When combined with a VR headset, the user will experience change in speed and direction within a virtual environment. Some known VR locomotion systems only provide forwards/backwards movement; the present invention is capable of omni-directional movement and positional correction.
After activating the system and after a period of movement by the user (several seconds or minutes, for example), the user may have stopped, changed direction and started walking again, or taken side steps. Over time, this will cause the user to drift away from the centre of the play area, as shown in
As the user walks in the forward direction, when either of the VR footwear assemblies is lifted off the ground, the opposite VR footwear assembly performs the inverse movement. High torque Brushless DC (BLDC) Motors provide a low latency response rate and PID control ensures the desired speed is achieved rapidly as load changes. Both VR footwear assemblies communicate wirelessly using a radio link such as Bluetooth, Wi-Fi, or generic packet radio for digital transmission. This is configured to relay a constant stream of data between each VR footwear assembly and a central controller, which also connects to a computer 40 (see
To provide compensatory movements in all directions, not just forwards/backwards, each VR footwear assembly has two motor drive modules (front and rear) which independently rotate 180°, or +90° to −90° around a centre position. Rotating these drive modules allows lateral (sideways) movement to occur. The magnitude of the lateral movement depends on the angle at which the two drive modules are rotated, for example +/−90° would result in full sideways movement and zero forward movement, whereas +5° would result in substantial forwards/backwards movement while at the same time a small lateral movement. The resulting vector of distance and direction depends on the speed of drive motors and drive module angle, which is determined by a control system for walking and positional correction. This closed loop control system receives inputs from number of sensors, including but not limited to optical, magnetic, MEMSs accelerometers, magnetometers and gyroscopes. The control system outputs signals to control drive motors and turn motors, as well as speed and direction data which is sent to the VR environment computer.
In addition to the BLDC motors, there are also turn motors embedded within the central part of each drive module that provide the rotation through a set of gears. The turn motors may be stepper motors or geared DC motors (also known as servos). The geared attachment mechanism allows wires to pass through from the rotating drive module to the electronics housing in the middle section of each VR footwear assembly. There is also a position feedback sensor coupled to the rotation motors either directly or by a gear, which allows measurement and precise control of the rotation angle. The absolute rotation angle can be determined, allowing the centre position (0°) to be found and the correct position to be verified during operation.
Each VR footwear assembly tracks its own location on a two dimensional surface (environment floor) using optical sensors. No tracking sensor devices external to the VR footwear assemblies are required in order to track the position of the VR footwear assemblies. Sensors detect when each VR footwear is lifted off the surface, by means of optical sensors, acceleration sensors or mechanical contacts switches. The speed of each drive motor is measured using magnetic or optical based sensors attached or integrated into each motor. The surface tracking is based on a relative coordinate system, where the centre of the user's play area is the origin (e.g. 0,0) and may be determined by the starting position or otherwise configured by the VR environment computer. The user's actual position and direction (or heading) is determined from sensors on each VR footwear assembly and transmitted between each VR footwear assembly, and/or to an external processing device or VR environment computer.
The external processing device or VR environment computer calculates a correction vector at least once for every stride (or single step) made by each foot. This correction vector represents the distance and direction between the actual coordinate of the user's body centre and the origin (starting position) coordinate. The correction vector and the actual heading of each VR footwear assembly are used to calculate the rotation angle of each drive module and to adjust the speed of the drive motors (faster/slower than user's actual walking speed) in order to correct the user's position over time.
Beneath the flexible platforms 18, 20 is a rigid chassis 26, which bends at the transverse hinge 22 and to which are mounted two independently rotatable drive modules, a rear drive module 28 and a front drive module 30. Each drive module 28, 30 has a rigid drive frame 28a (see
Referring now to
The drive frames 28a, 30a support the motors 34, drive wheels 36 and pulley wheels 38 and, when combined with the drive module cover 30b provide a strong and rigid support for the wheels on each side. The frames and chassis also provide channels for routing wires and cables, and space (mainly in the centre of the chassis, between the two drive frames) for locating electronics, sensors, and receiver/transmitters for communicating with an external VR computer 40 (shown in
Turning to
One of the objectives of the VR footwear assembly design is to support the weight of a person (i.e. about 100 kg), this is the load that each VR footwear assembly is designed to handle. This weight is distributed across a total of eight Pulleys, where each pair of wheel pulleys (forward and rear) is designed to cope with the largest dynamic loads. The four motors generate a high torque relative to their size, which is transferred through four independent belts. The speed of each motor is regulated using a feedback signal and a PID control loop. There are a number of advantages to this design, compared to a design with one or two motors: the compact arrangement of four motors allows the device to have a low profile (˜45 mm from ground excluding the heel cup 14 and battery pack 42). Such a low profile and even mass distribution within the device, together with the large surface contact area provided by the belts, results in a stable platform to walk-on, with high surface traction.
The rear drive module 28″ (which could equally be a front drive module) shown schematically from beneath with both continuous drive belts and one drive wheel removed for clarity has a single drive motor 34″ which, as with the embodiments described above, drives one splined drive wheel 36″ to drive the continuous belts (not shown) via a transversely-splined drive wheel 58 and a toothed primary drive belt 56″. The illustrated drive wheel 36″ is fixed to one end of a shaft 66″ extending transversely across the drive module 28″ and which is rotatably supported by bearings (not shown) within the drive assembly 28a″ and/or the drive frame cover 28b″. The other drive wheel (not shown for clarity) is fixed to the other end of the shaft 66″, so that as the motor 34″ drives the belt 56″ and the drive wheel 36″, the drive wheel on the other side of the drive module is driven in unison so that both continuous drive belts are driven together.
The footwear assembly described above is normally one of a pair for each user and has the following features and characteristics:
Each VR footwear assembly can be configured to be worn either directly on a user's foot, where a cushioned sole is attached to the upper surface of the platform, or alternatively the footwear device may be strapped to a person that is wearing normal shoes, in which case the cushioned sole may be removed by the user and shoes placed directly onto the platform, and held in place using a system if straps. The cushioned sole is designed to provide comfort as well as keeping the user's foot in the correct position, additionally multiple straps hold the foot onto the device.
It will of course be understood that many variations may be made to the above-described embodiments without departing from the scope of the present invention. For example, the heel cap and/or platforms may incorporate means to adjust for different foot sizes, so that the assemblies can be easily adapted for use by other users. The platforms are shown as flat but they could be moulded to accept lower surface of the foot, to provide a more comfortable fit. The battery pack may be located in a different location than as shown, for example it may be located under the heel support and re-configured as a flattened battery pack; the same applies to the electronics/sensor/transmitter receiver elements, these may also move from the central chassis location, such as by being located behind the heel cup, packaged as a small box. Whilst the footwear assembly has been described in connection with VR equipment, this is not essential; the VR footwear assembly could be used without AR/VR equipment, for example rehabilitation in Health Care, where this type of locomotion system is used by patients regaining the ability to walk. The upper platforms 18, 20 which are intended for a foot, may be swapped/exchanged for different platforms designed to accommodate a shoe with fixings and straps as appropriate. The heel cup 14 may be mounted to the rear end 12 by way of a slide arrangement or the like so that the position of the heel cup on the rear end can be adjusted in a forward or rearward direction; this allows the footwear assembly to fit and be used by persons having smaller or bigger feet. The pulley and/or drive wheels may be adjustably mounted so as to place the continuous belts under tension, and the directly driven drive wheel may be similarly adjustable to tension the primary drive belt. The outer surface of each belt is shown in the drawings as smooth, but there may be a tread pattern (such as simple transverse ribs, or a more complicated configuration) provided to improve traction. The drive modules in a footwear assembly may be any combination of any of the different drive modules shown in
Where different variations or alternative arrangements are described above, it should be understood that embodiments of the invention may incorporate such variations and/or alternatives in any suitable combination.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2111576.1 | Aug 2021 | GB | national |
| 2202740.3 | Feb 2022 | GB | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/072474 | 8/10/2022 | WO |
