A device for tracking hand movements of a user

Abstract

A device for tracking hand movements of a user, the device comprising : at least one digit unit comprising two digit sensing modules, each digit sensing module comprising a sensor, a sensor housing and a digit holder extending from the sensor housing, the digit holder being configured to receive a digit of the user wherein the digit holder comprises an adjustable internal dimension determined according to a digit of the user; a hub configured to receive data from the at least one digit unit; and a processor configured to process data received by the hub.

Description

[0001]A DEVICE FOR TRACKING HAND MOVEMENTS OF A USER This invention relates to a device for tracking hand movements of a user and a method of manufacturing said device for tracking hand movements of a user. Known devices for tracking hand movements of a user comprise a glove or glove-like structure with sensors and other electrical components fixed thereto. It will be appreciated that a ‘glove or glove-like structure’ will be considered as a structure configured to receive a human hand including four fingers and a thumb, a palm and, at least partially, a wrist. According to a first aspect of the invention, there is provided a device for tracking hand movements of a user, the device comprising: at least one digit unit comprising two digit sensing modules, each digit sensing module comprising a sensor, a sensor housing and a digit holder extending from the sensor housing, the digit holder being configured to receive a digit of the user wherein the digit holder comprises an adjustable internal dimension determined according to a digit of the user; a hub configured to receive data from the at least one digit unit; and a processor configured to process data received by the hub. A disadvantage of known glove or glove-like structures for supporting devices used to track hand movements is that they are not customisable to a specific user and instead rely on a ‘one-size-fits-all’ approach. This approach is particularly ineffective when applied to devices intended for use by children of different ages and widely varying hand sizes. Also, devices for tracking hand movements are of particular use for habilitative or rehabilitative exercises and therapies for people with cerebral palsy (CP) or people other disorders or disabilities affecting a person’s upper limb, such as Stroke patients. Such individuals may already suffer from discomfort in their hands which may exacerbated by an ill-fitting glove or glove like-structure. Such individuals may also hold their hands in an atypical way which might be restricted by a glove or glove-like structure designed only with typical hand gestures and shapes in mind. Furthermore, individuals with atypically shaped hands or missing digits, such as amputees, may find it very difficult or impossible to wear a traditionally designed glove or glove-like structure. Another consideration is that accurate tracking of hand movements, particularly accurate tracking of individual digit movements, requires sensors to be securely fastened to the relevant parts of the hand so that measurements can be made reliably and repeatably. An ill-fitting glove or glove-like structure, with no customisation to a specific user, is unlikely to provide the level of stability of sensors relative to that user’s hand that is required to ensure accurate measurements for that user. In other words, the sensors would be measuring the movements of the glove or glove-like structure, but this may not be an accurate reflection of the user’s hand movements. By means of the invention, each sensor used for measuring the user’s hand movements is securely attachable to a respective digit of the user via the sensor housing and digit holder which comprises an adjustable internal dimension determined according to a digit of the user. In other words, each digit holder is sized according to the size of the specific user’s digit it is intended to hold. The internal dimension may be an internal diameter, an internal circumference, an internal volume or any other internal dimension of the digit holder which may correspond to a respective dimension of the user’s digit. Although each digit holder is sized according to the size of the specific user’s digit it is intended to hold, it is understood that the exact size of a digit will vary over time. For example, fingers are prone to swelling in warmer temperatures and contraction in cooler temperatures. Also, a child’s growth may result in increased digit circumference, even within a period of time that a rehabilitation program may be expected to extend over. Accordingly, providing the digit holder with adjustability allows the digit holder to securely and comfortably attach the sensor to the user’s digit despite size-fluctuation or growth of the digit in question. With respect to the processor, processing data received by the hub may include at least one of: classifying and sorting raw data received by the hub; transforming raw data into spatial positioning data; and transmitting the data to be used in a virtual reality (VR) or augmented reality (AR) environment, for example as part of a game- based therapy. In some embodiments, the processor may comprise a plurality of processors. In some embodiment of the invention the processor(s) may be configured to communicate with one or more processors forming part of a third-party device, such as a personal computer, tablet, smart TV, smart phone, games console or VR headset, which may generate the virtual reality (VR) or augmented reality (AR) environment. In embodiments of the invention, each digit holder may comprise two grips extending from the sensor housing in different directions, each grip having a first end coupled to the sensor housing and a second end overlapping the other grip. The provision of two grips that wrap around the user’s digit in different directions provides the digit holder with adjustability while the overlapping of both second ends ensures that the digit holder remains comfortable and the sensor remains secure as the internal dimension of the digit holder expands to receive the digit. In embodiments of the invention, the grips of at least one digit holder may overlap in an axial direction and the second end of both grips may be joined together by a strut. Additionally or alternatively, the grips of at least one digit holder may overlap in a radial direction and the second end of both grips may be movable independently of one another. In embodiments of the invention, each digit holder comprises a material suitable for additive manufacturing. Any material suitable for additive manufacture may be used. In some embodiments of the invention, thermoplastic polyurethane (TPU) is used because its inherent flexibility improves the adjustability and comfort of the digit holders. Accordingly, each digit holder may be manufactured using an additive manufacture technique to have the adjustable internal dimension determined according to a digit of the user. Additive manufacturing provides improved capability to customise the adjustable internal dimension to a specific user. For example, the digit holder may be 3D printed according to a model modified according to measurements of the user’s digit user. Despite the customisation involved, the digit holder can be manufactured in a matter of hours, or even minutes, following measurement of the user’s digits. In embodiments of the invention, for each digit sensing module, the adjustable internal dimension may comprise a maximum internal circumference determined to be a predetermined amount larger than a measured finger circumference of the user, and a minimum internal circumference determined to be a predetermined amount smaller than the measured finger circumference of the user. In embodiments of the invention, the hub may comprise a processing module attachable to the user and comprising the processor. In embodiments of the invention, the hub may comprise a connection module attachable to the user and being electrically connectable to the at least one digit unit. The connection module may be connectable to up to at least five digit units and may comprise at least one further sensor. In some embodiments, the hub may be in the form of a single unit which may be attachable to the user’s body. In other embodiments, the hub may comprise multiple units which may be individually attachable to the user’s body. In other words, the processing module and connection module may be joined in a single unit or may be separate units connected to one another via a wired and / or wireless connection. The hub may further comprise a power source, such as a replaceable battery or a rechargeable battery. The hub may alternatively comprise a connection port for receiving a power cord configured to supply power from a remote source such as an external battery. Or, the hub may comprise a power cord configured to be received by a remote connection port and allow for power to be supplied from a remote source such as mains electricity. In embodiments of the invention, each digit unit may comprise a digit connector connecting the two digit sensing modules to one another and which may also be connectable to the connection module. Preferably, the digit connector is flexible to avoid limitation of the user’s hand movement. Also, the digit connector may be detachably connectable to the connection module, thereby providing the device with modularity to enable further customisation to a specific user. In some embodiments, the digit connector may be a physical connector such as a cable along which electrical and / or optical signals may be transmitted. In other embodiments, the digit connector may be a means for wireless connection, such as a network of Bluetooth®or Wi-Fi™ transmitters and receivers. In further embodiments, the digit connector may comprise a combination of physical (or ‘wired’) connections and wireless connections. The digit connector may allow power to be transmitted from the hub to the sensors as well as allowing measured data to be transmitted from the sensors to the hub, particularly the processor. In embodiments of the invention, the processor may be configured to detect the number of digit units connected to the connection module. Further, the processor may be configured to identify each digit unit connected to the connection module according to a user’s digit. Therefore, the processor may be able to detect that three digit units are connected to the connection hub and may also be able to identify which digits of the user the digit units are fitted to (e.g., the thumb, index finger and middle finger). This may negate the need for the wearer, or other operator (such as a physiotherapist), of the device to manually calibrate the device in this regard. In embodiments of the invention, each sensor housing may be configured to encase the respective sensor. In embodiments of the invention, the device may further comprise a splint to which the hub is mounted. People with CP may wear a splint, which may be defined as a brace, orthosis, cast, or any similar external structure applied to one or more joints, to correct the position of a grip, prevent contractures and allow a wearer to assume a more functional hand position, that may support the execution of motor tasks and / or prevent deformity. It may be counterproductive if a person is unable to wear the device for tracking hand movements while also wearing a splint, particularly if the splint assists that person in performing active hand movements. Accordingly, embodiments of the invention combine the two elements together. However, a person’s usual splint (the splint that the person wears on a day-to-day basis) may be configured uniquely for that person and may include one or more design elements having a specific therapeutic purpose. It may therefore be uncomfortable or otherwise ineffective to replace that splint with a differently designed splint when using the device. Accordingly, in embodiments of the invention, the splint may be configured according to a pre-existing splint belonging to the user and modifications for the mounting of the hub. In other words, the device may comprise a splint designed to replicate the user’s usual splint in form and fit except that it also has features necessary to mount elements of the device, such as the hub, to the splint. In embodiments of the invention, the splint may comprise a material suitable for additive manufacturing so that an additive manufacturing technique can be used to produce the splint, replicating the user’s pre-existing splint, with minimal delay. In embodiments of the invention, each sensor may be a motion capture sensor, optionally comprising an inertial measurement unit. According to a second aspect of the invention, there is provided a modular device for tracking hand movements of a user, the device comprising: at least one replaceable digit unit comprising two digit sensing modules, each digit sensing module comprising a sensor, a sensor housing and a digit holder extending from the sensor housing, the digit holder being configured to receive a digit of the user; a hub configured to receive data from the at least one replaceable digit unit; and a processor configured to process data received by the hub. The features and advantages of the first aspect of the invention and its embodiments apply mutatis mutandis to the second aspect of the invention and its embodiments. For example, in embodiments of the invention, the hub may comprise a connection module attachable to the user and being electrically connectable to the at least one replaceable digit unit. Further, the connection module may be connectable to up to at least five replaceable digit units at any one time. Also, in embodiments of the invention, each digit unit may comprise a digit connector connecting the two digit sensing modules to one another. The digit connector may be detachably connectable to the connection module, thereby providing the device with its modularity. The modularity of the device enables digit units to be interchanged and replaced at will. For example, a damaged digit unit may be replaced. Also, if the user is a child and outgrows a first set of digit units, new digit units may be provided to the user that have digit holders with an increased internal dimension. This means that only the digit units require replacement and not the entire device. The modularity can also allow multiple users to take turns using a single hub while each using unique digit units, thereby making the device more accessible while maintaining the device’s personalisation to specific users. In embodiments of the invention, the processor may be configured to detect the number of digit units connected to the connection module. Further, the processor may be configured to identify each digit unit connected to the connection module according to a user’s digit. Therefore, the user may decide how many digit units to use and which digits to wear them on. Moreover, the user may be able to do so without needing to manually calibrate the device according to the chosen configuration. This may be particularly useful if the user is focusing on particular rehabilitative exercises concerning only certain digits, of if the user has fewer than five digits. Using only three digit units, for example, may also provide the user with a cost saving in comparison to using five digit units, thereby making the device more accessible. In embodiments of the invention, each digit holder comprises an adjustable internal dimension determined according to a digit of the user. According to a third aspect of the invention, there is provided a method of manufacturing a device for tracking hand movements of a user, the method comprising: creating a profile for the user comprising first and second digit dimensions for at least one digit; using an additive manufacturing technique to manufacture first and second digit sensing modules, each digit sensing module comprising a sensor, a sensor housing and a digit holder, each digit holder having an adjustable internal dimension determined according to the first and second digit dimensions in the profile, respectively; and assembling the device comprising a processor, a hub and at least one digit unit comprising the first and second digit sensing modules. The features and advantages of the first and second aspects of the invention and their embodiments apply mutatis mutandis to the third aspect of the invention and its embodiments. Creating a profile for the user may comprise measuring and recording anthropomorphic data to form part of the user’s profile, including first and second digit dimensions for at least one digits, preferably all five digits of one or both hands. Measuring the anthropomorphic data may be done manually or with the aid of an automated system and / or method, 3D scanning methods may be used for example. By means of the invention, a prospective user of a device for tracking hand movements may have necessary measurements taken and a customised device may be manufactured according to those measurements with a very short lead time. For example, the device may be ready for calibration and use in the same day that the measurements are taken. Any suitable additive manufacturing technique may be used. One such example is fused deposition modelling (FDM). In embodiments of the invention, manufacturing each digit sensing module may comprise: using a first printer head, configured for printing a first material, to 3D print the sensor housing; using a second printer head, configured for component gripping, to mount a sensor to the sensor housing; using a third printer head, configured for printing a second material, to 3D print the digit holder. Any materials suitable for additive manufacturing techniques may be used as the first and second materials. In some embodiments of the invention, the first material may be polylactic acid (PLA) because its mechanical properties provide a sensor housing that supports, and optionally encloses, the sensor securely. The second material may be TPU because its inherent flexibility improves the adjustability and comfort of the digit holders. Further, PLA and TPU exhibit favourable adhesiveness to one another when printed together, making the combination of the two materials especially practical for this application. These materials are also available in various colours, which can cater to the users’ different preferences. Thus, the device can be easily additive manufactured depending to a child’s colour preferences, thereby making the device more attractive to wear so that the child is encouraged to continue the exercises forming part of their therapy. The second printer head may comprise any suitable means for mounting the sensor to the sensor housing. For example, the second printer head may comprise a vacuum suction tool. Such embodiments of the invention may comprise using a multi-head 3D printer capable of operating with a variety of different printer heads and automatically switching between the printer heads as required. It will be appreciated that the 3D printer may alternate between the first, second and third printer heads, numerous times, in the process of manufacturing each digit sensing module. In embodiments of the invention, each digit holder may comprise two grips extending from the sensor housing in different directions, each grip having a first end coupled to the sensor housing and a second end overlapping the other grip. In embodiments of the invention, 3D printing each digit holder may comprise printing each grip directly into connection with the sensor housing, whereby the grips extend vertically from the sensor housing, overlap in an axial direction and the second end of both grips are joined together by a strut. In embodiments of the invention, 3D printing each digit holder may comprise printing each grip such that each grip extends from its first end to its second end in a horizontal direction, the grips overlap in a radial direction and the second end of both grips are movable independently of one another. In such embodiments of the invention, the step of using a second printer head, configured for component gripping, to mount a sensor to the sensor housing may not be suitable. Rather, the method may comprise a separate step of manually mounting a sensor to the sensor housing. In embodiments of the invention, manufacturing the first and second digit sensing modules may comprise 3D printing each digit holder such that the adjustable internal dimension comprises a maximum internal circumference that is a predetermined amount larger than a respective digit circumference of the profile, and a minimum internal circumference that is a predetermined amount smaller than the respective digit circumference of the profile. In embodiments of the invention, the method may further comprise using an additive manufacturing technique to manufacture a splint to which the hub is mounted during assembly of the device. In embodiments of the invention, the method may further comprise, prior to manufacturing the splint: 3D scanning a pre-existing splint belonging to the user to create a splint model; and modifying the model for the mounting of the hub; wherein manufacturing the splint comprises 3D printing the splint according to the modified model. It will be appreciated that the use of the terms “first” and “second”, and the like, in this patent specification is merely intended to help distinguish between similar features and is not intended to indicate the relative importance of one feature over another feature, unless otherwise specified. Within the scope of this application, it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, and the claims and / or the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and all features of any embodiment can be combined in any way and / or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and / or incorporate any feature of any other claim although not originally claimed in that manner. Preferred embodiments of the invention will now be described, by way of non-limiting examples, with candidate to the accompanying drawings in which: Figures 1 and 2 show schematically a device according to a first embodiment of the invention; Figure 3 shows schematically a device according to a second embodiment of the invention; Figures 4 and 5 show schematically alternative examples of a digit sensing module that may form part of the devices shown in Figures 1 to 3; Figure 6 shows schematically the device of Figures 1 and 2, particularly the internal components thereof; Figure 7 shows schematically a device according to a third embodiment of the invention; and Figure 8 shows schematically a method according to a fourth embodiment of the invention. The figures are not necessarily to scale, and certain features and certain views of the figures may be shown exaggerated in scale or in schematic form in the interests of clarity and conciseness. A device according to a first embodiment of the invention is shown in Figures 1 and 2 and is designated generally by the reference numeral 2. The device 2 is being worn by a user 4 and comprises a hub 6 and a plurality of digit units 8. In this embodiment, the hub 6 comprises a processing module 10 and a connection module 12, each of which is attachable to the user 4. The hub 6 further comprises a hub connector 14 providing a flexible electrical connection between the processing module 10 and connection module 12. However, in other embodiments of the invention, the hub 6 may be provided as a single unit or the processing and connection modules may be wirelessly connected to one another. Each digit unit 8 comprises two digit sensing modules 16, 17 and a digit connector 18 electrically connecting the two digit sensing modules to one another. Each digit connector 18 is also connectable to the connection module 12, thereby electrically connecting each digit sensing module 16, 17 to the connection module 12 and, in turn, the processing module 10. Each digit connector 18 is flexible to avoid restricting movements by the user 4. The digit connector 18 is also detachable from the connection module 12 such that the digit units 8 may be considered interchangeable and replaceable and the device 2 may be considered modular. In use, a first digit sensing module 16 of each digit unit 8 is fitted to the user’s respective digit between the digit’s proximal and intermediate joints. Meanwhile, a second digit sensing module 17 is fitted to the user’s respective digit between the digit’s intermediate and distal joints. For the thumb, which has no intermediate joint, the first digit dimension may be measured between the proximal and distal joints and the second digit dimension may be measured between the distal joint and the nail, for example. Known glove or glove-like devices used to track hand movements include additional sensors located on, or near to, the user’s fingertips. In contrast to this known practice, the device 2 includes only two digit sensing modules 16, 17 on each digit and allows the fingertips to be free from obstruction. In addition to maintaining the user’s natural touch sensitivity while using the device 2, the reduced number of sensors reduces the complexity and cost of the device with minimal loss of accuracy as movement of the distal joint (i.e., fingertip movement) can be extrapolated with sufficient accuracy from the flexion / extension of the intermediate joint. In this embodiment, the device 2 comprises five digit units 8, each of which is worn on a separate digit of the user 4. However, in another embodiment shown in Figure 3, a device 102 comprises just three digit units 8, worn on the thumb, index finger and middle finger of the user 4. In every other way, the device 2 and 102 are identical. In further embodiments, the device may be used with just one digit unit 8 or any number of digit units up to five. In even further embodiments, it is feasible for a user to wear more than one digit unit on a particular digit. Accordingly, the connection module 12 may be configured to connect to more than five digit units at any one time. Figure 4 shows an example of a digit sensing module 16. The digit sensing module 16 comprises a sensor housing 20 and a digit holder 22. In this embodiment, the sensor housing comprises an enclosure 24, which houses a sensor (not shown), and a connector port 26 for receiving the digit connector 18 shown in Figure 1. The digit holder 22 comprises two grips 30 extending from the sensor housing 20 in different directions. Each grip 30 having a first end 31 coupled to the sensor housing 20 and a second end 32 overlapping the other grip 30. In this embodiment, the grips 30 overlap in an axial direction and the second ends 32 are joined together by a strut 34. It is to be understood that the digit holder 22 is configured to receive a digit of a user such that the digit extends along an axis through the digit holder. Accordingly, the axial direction may be considered as the direction in which a digit would extend through the digit holder 22. The grips 30 of the digit holder are configured to enable additive manufacturing to be used to manufacture the digit sensing module 16 while it is oriented vertically, as shown in Figure 4. Printing the digit sensing module 16 vertically enables a multi-head 3D printer to 3D print and assemble the entire digit sensing module without requiring manual intervention. One or more printer heads may be used to print the sensor housing 20 and digit holder 22 while a separate printer head configured for component gripping may mount a sensor (not shown) into the sensor housing 20 at the appropriate time within the printing process. This automation reduces manufacturing time and cost because a manual step of mounting a sensor into the sensor housing 20 is avoided. However, due to limitations of known 3D printing apparatuses, which are generally capable of printing in a vertical direction only, the grips 30 cannot extend past one another to the extent that the printing quality of the grips 30 would be compromised. If the grips 30 were free-standing, independently of one another, from the sensor housing 20, limiting the degree to which the grips 30 overlap past one another would also limit how securely the grips 30 would be able to hold a digit without causing discomfort. The strut 34 is therefore provided to improve the strength of the digit holder 22 when gripping a digit without needing to make the grips 30 more rigid and uncomfortable. Figure 5 shows an alternative embodiment of a digit sensing module 216. The sensor housing 20 is identical to that of the digit sensing module 16 shown in Figure 2. However, in this embodiment, a sensor (not shown) is mounted into the sensor holder 20 as a separate, manual step. This means that the grips 230 may be 3D printed so that they extend horizontally across a printing bed, rather than extending vertically from it, because vertical orientation of the sensor housing is not required. Accordingly, although manufacturing this embodiment of the digit sensing module 216 requires an additional manual step of mounting the sensor, the limitations on the configuration of the grips 230 are reduced. The grips 230 may overlap one another in a radial direction and to a much greater extent than the grips 30 of the digit sensing module 16 shown in Figure 2. The radial direction may be considered with respect to a user’s digit once received within the digit holder if the digit is modelled as a cylinder. The radial overlapping and the fact that the second ends 232 of the grips 230 extend further past one another means that the digit holder 222 is able to grip a digit more securely without being uncomfortable and without requiring a strut to join the grips 230 together to provide additional strength and stability. Either of the digit holder configurations shown in Figures 4 and 5 may be used. The choice may be determined by manufacturing constraints. For example, the configuration shown in Figure 4 may be preferred so to enable greater automation of manufacturing. The choice may also be determined by considering how much flexibility in digit size is required. For example, if the same digit sensing units are to be shared by different users then the greater flexibility of the configuration shown in Figure 5 may be preferable. Also, the choice may ultimately be made by the user depending on which configuration is found to be more comfortable and / or secure. Figure 6 shows internal components of the device 2 shown in Figures 1 and 2. Although the external components of the device 2 are hidden it will be appreciated that the internal components are housed within the corresponding external components shown in Figures 1 and 2. The processing module 10 comprises a processor 36 configured to process data received by the hub 6 from the digit sensing modules 16, 17 via the digit connectors 18, connection module 12 and hub connector 14. In this embodiment, the processor 36 is configured to detect the number of digit units 8 connected to the connection module 12. Furthermore, the processor 36 is configured to identify each digit unit 8 connected to the connection module 12 according to a user’s digit. In other words, based on the data processed by the processor 36, the processor 36 is able to detect how many digit units are connected and the digits that they are being used for. In this embodiment, the connection module 12 comprises a connection board 38 comprising connection ports adapted to receive the digit connector 18 of a digit unit 8. The processor 36 may determine the number and arrangement of digit units 8 according to the connection ports through which it is receiving data. In other embodiments, which may involve wireless connections for example, each digit unit may be assigned to a particular digit and data received from each digit unit may be tagged with information identifying the digit unit that transmitted the data, thereby allowing the processor to identify the number and arrangement of digit units being used. In some embodiments, the processor 36 may be configured to estimate the size of a user’s hand and / or update an existing model of the user’s hand using data received from each digit unit 8, particularly the distance between the digit sensing modules 16, 17. The accuracy of this functionality may depend on the precision with which the digit sensing modules 16, 17 can be fitted to the user’s digits. Preferably, each digit sensing module 16, 17 would be positioned equidistantly between the adjacent joints of the respective digit. Monitoring the size of the user’s hand may be particularly beneficial if the user is a child whose hand may grow considerably during an extended period of using the device. The processor may additionally be configured to issue an alert to a guardian or clinician to signify that the user’s hand has grown sufficiently to consider the creation of new digit sensing modules 16, 17 with larger digit holders 22, 222. In further embodiments, the processor 36 may be configured to detect if the device 2 is being worn on the user’s right or left hand. This configuration of the processor may be achieved in a number of different ways. In one example, the processor may be configured to receive a signal indicating whether the device 2 is worn on the right or left hand. The signal may be transmitted by a third-party device, such as a personal computer, tablet, smart phone, smart TV, games console or VR headset, and transmission of the signal may be instigated by the user pushing a button on a touchscreen or carrying out an equivalent action. In another example, particularly if fewer than five digit units 8 are used (e.g., three digit units for the thumb and first two fingers), the processor 36 may be configured to identify which connection ports the digit units 8 are connected to / not connected to and infer the hand being used accordingly. In a further example, particularly if five digit units 8 are used, the processor may be configured to identify which two adjacent sensors are not in alignment along corresponding axes of the sensors (this is information that may be captured in data received from the sensors). Since the digit sensing modules used for the user’s thumb have a start position oriented significantly away from parallel with the digit sensing modules used for the user’s finger, the processor may be configured to infer which digit unit 8 is being used for the user’s thumb and, hence, the hand on which the device 2 is being worn. The connection module 12 further comprises a hand sensor 42. In this embodiment of the invention, the hand sensor 42 comprises an inertial measurement unit (IMU) configured to measure flexion / extension of the wrist, radial / ulnar deviation and wrist rotation. Data representative of these measurements is then transmitted from the hand sensor 42 to the processor 36 via the hub connector 14. Each digit sensing module 16, 17 also comprises a digit sensor 44 mounted to the sensor housing 20. More specifically, in this embodiment of the invention, each digit sensor 44 is housed in the enclosure 24 of the respective digit sensing module 16, 17. In this embodiment of the invention, each digit sensor 44 comprises an IMU configured to measure both flexion / extension and abduction / adduction of the respective digit. In practice, the digit sensors 44 may be identical to the hand sensor 42. However, the processor 36 may be configured to ignore certain data measured and transmitted by the hand sensor 42 which is not useful for understanding the hand’s spatial positioning. In other embodiments of the invention, types of sensor other than IMUs may be used for the hand sensor, digit sensors, or both, provided that the processor is suitably configured to process the data measured by such sensors. Figure 7 shows a device 302 which is similar to the device 2 shown in Figures 1 and 2 except that it further comprises a splint 350 and the hub 306 is suitably modified to be attached to the user 4 via the splint rather than a direct attachment. In this embodiment, the splint 350 is configured according to a pre-existing splint belonging to the user 4 and modifications for the mounting of the hub. In this example, the user 4 has CP and, before using the device 302 for the first time, already had a splint specially designed to assist with motor tasks. Designing the splint 350 according to that pre-existing splint therefore avoids the user 4 having to sacrifice the benefits that the pre-existing splint provided in order to use the device 302. The splint 350 comprises a material suitable for additive manufacturing so that an additive manufacturing technique can be used to produce the splint 350, replicating the user’s pre-existing splint, with minimal delay. Figure 8 shows a method 400 of manufacturing a device for tracking hand movements of a user, such as the devices 2, 102 and 302 shown in the preceding figures. Accordingly, the method 400 is described below with reference to features shown in Figures 1 to 7. However, it is to be understood that other embodiments of a device for tracking hand movements of a user may also be manufactured with the same steps. The method 400 comprises: 402) creating a profile for the user 4 comprising first and second digit dimensions for at least one digit; 404) using an additive manufacturing technique to manufacture first and second digit sensing modules 16, 17, each digit sensing module 16, 17 comprising a digit sensor 44, a sensor housing 20 and a digit holder 22, each digit holder 22 having an adjustable internal dimension determined according to the first and second digit dimensions in the profile, respectively; and 406) assembling the device 2 comprising a processor 36, a hub 6 and at least one digit unit 8 comprising the first and second digit sensing modules 16, 17. Step 402 may comprise measuring and recording anthropomorphic data to form part of the user’s profile, including first and second digit dimensions for at least one digits, preferably all five digits of one or both hands. The first digit dimension may be a diameter, circumference or volume of the user’s respective digit between the digit’s proximal and intermediate joints. The second digit dimension may be a diameter, circumference or volume of the user’s respective digit between the digit’s intermediate and distal joints. For the thumb, which has no intermediate joint, the first digit dimension may be measured between the proximal and distal joints and the second digit dimension may be measured between the distal joint and the nail, for example. Step 402 may further comprise measuring and recording additional data of the user such that the profile includes the user’s: - Age; - Gender; - Types of sensory, motor and / or cognitive disabilities (if any); - Functional goals; and - Aesthetic preferences (e.g., a colour preference for the device). Step 402 may be carried out during a consultation between a clinician who ideally is a Rehabilitation specialist such as an Occupational Therapist or Physiotherapist and the user 4. If the user 4 is a child, a guardian of the child may also be present and involved. In one example, the data may be entered by the clinician into an electronic framework and uploaded to backend software stored in cloud-based storage. However, other means of recording and storing data that are well known to those skilled in the art may also be used. Step 404 comprises using an additive manufacturing technique to manufacture first and second digit sensing modules 16, 17 according to the user’s profile. In particular, the first and second digit dimensions are used to manufacture the first and second digit sensing modules 16, 17 so that the digit holders 22 have suitable internal dimensions. For example, manufacturing the first and second digit sensing modules 16, 17 may comprise 3D printing each digit holder 22 such that the adjustable internal dimension comprises a maximum internal circumference that is a predetermined amount larger than a respective digit circumference of the profile, and a minimum internal circumference that is a predetermined amount smaller than the respective digit circumference of the profile. Other manufacturing considerations may also be based on the user’s profile. For example, the digit sensing modules may be manufactured with a material coloured in accordance with the user’s aesthetic preferences. Also, if the user’s functional goals were focussed on motor skills using the thumb and index finger only, then step 404 may comprise manufacturing digit sensing modules only for those two digits, for example. In this embodiment of the invention, manufacturing each digit sensing module 16, 17 comprises: using a first printer head, configured for printing a first material, to 3D print the sensor housing 20; using a second printer head, configured for component gripping, to mount a sensor 44 to the sensor housing 20; using a third printer head, configured for printing a second material, to 3D print the digit holder 22. More particularly, 3D printing each digit holder 22 comprises printing each grip 30 directly into connection with the sensor housing 20, whereby the grips 30 extend vertically from the sensor housing 20, overlap in an axial direction and the second end 32 of both grips 30 are joined together by a strut 34. In other words, the digit holders 22 are 3D printed according to the configuration shown in Figure 4. This means that the manufacturing of each digit sensing unit 16, 17 may be largely automated, allowing for fast and cost effective preparation of the device. However, some post processing of the 3D printed parts may be required to remove support material before the digit sensing modules are ready to use. If the configuration of the digit sensing unit 216, shown in Figure 5, is used, mounting the sensor 44 in the sensor housing 20 may require a separate, manual step. Step 406 comprises assembling the device 2. However, it will be appreciated that other components which form part of the device may be manufactured using additive manufacturing techniques, similarly to the digital sensing modules. In particular, the hub 6 may comprise 3D printed parts. By virtue of being 3D printed, additional customisation for a particular user is available. As with the digit sensing modules, the colour of the materials used may be selected according to the user’s profile. Further examples of customisation according to the user’s profile include the size of the hub 6 / processing module 10. In some examples the hub 6 / processing module 10 may comprise replaceable or rechargeable batteries. If the intended user is a child, a lightweight configuration may be manufactured with a smaller battery pack so that the child is not carrying a heavy weight for prolonged periods of time. On the other hand, if the intended user is an adult, a durable configuration may be manufactured with a larger batter for extended battery life because the added weight would be less of a burden. Another example of potential customisation available to the user by virtue of 3D printing parts of the device 2 is the ability to include decoration of the parts. Such decoration may include printing the parts to appear as though words, initials or other characters are engraved into the respective parts. In particular, including an ‘engraving’ in the casing of the processing module 10 and / or connection module 12, which include larger surfaces, may be attractive to the user. In some embodiments, the method 400 may also comprise using an additive manufacturing technique to manufacture a splint 350 to which the hub 306 is mounted during assembly of the device 302. Prior to manufacturing the splint, the method may comprise 3D scanning a pre-existing splint belonging to the user 4 to create a splint model. This step may be considered as forming part of step 402 - creating a profile for the user 4. The model may then be modified to enable mounting of the hub 306 to the splint, as shown in Figure 7 for example. Manufacturing the splint 350 would then comprise 3D printing the splint 350 according to the modified model. Once assembled, the device 2, 102, 302 may be used to track hand movements of the user 4. For example, the user 4 may carry out rehabilitative exercises as part of a therapy program. Particularly if the user 4 is a child, the exercises may be incorporated into games incorporating virtual reality (VR) or augmented reality (AR) technologies to engage the child more effectively. The processor 36 of the device 2, 102, 302 may be configured to receive hand movement data from the sensors 42, 44 and apply that data to a VR- or AR-based game so that the user’s actions affect the VR- or AR-based game environment. The processor 36 may also be configured to record performance metrics such as game / task / activity success percentages and a log of play time. The processor 36 may further be configured to update the user’s profile with quantitative performance metrics such as accuracy, speed and endurance. For example, the processor may be configured to upload the performance metrics to backend software, for the device 2, 102, 302, stored in cloud-based storage. Additional qualitative parameters, such as level of enjoyment and satisfaction for the user, may also be uploaded to the same backend software. This may be done by the user or by a guardian / other caregiver. It will be appreciated that any aforementioned numerical value is merely intended to help illustrate the working of the invention and may vary depending on the requirements of the invention. The listing or discussion of an apparently prior published document or apparently prior published information in this specification should not necessarily be taken as an acknowledgement that the document or information is part of the state of the art or is common general knowledge. Preferences and options for a given aspect, feature or parameter of the invention should, unless the context indicates otherwise, be regarded as having been disclosed in combination with any and all preferences and options for all other aspects, features and parameters of the invention.

Claims

CLAIMS 1. A device for tracking hand movements of a user, the device comprising: at least one digit unit comprising two digit sensing modules, each digit sensing module comprising a sensor, a sensor housing and a digit holder extending from the sensor housing, the digit holder being configured to receive a digit of the user wherein the digit holder comprises an adjustable internal dimension determined according to a digit of the user; a hub configured to receive data from the at least one digit unit; and a processor configured to process data received by the hub.

2. A device according to Claim 1, wherein each digit holder comprises two grips extending from the sensor housing in different directions, each grip having a first end coupled to the sensor housing and a second end overlapping the other grip.

3. A device according to Claim 2, wherein the grips of at least one digit holder overlap in an axial direction and the second end of both grips are joined together by a strut.

4. A device according to Claim 2 or Claim 3, wherein the grips of at least one digit holder overlap in a radial direction and the second end of both grips are movable independently of one another.

5. A device according to any preceding claim, wherein each digit holder comprises a material suitable for additive manufacturing.

6. A device according to Claim 5, wherein each digit holder is manufactured using an additive manufacturing technique to have the adjustable internal dimension determined according to a digit of the user.

7. A device according to any preceding claim, wherein, for each digit sensing module, the adjustable internal dimension comprises a maximum internal circumference determined to be a predetermined amount larger than a measured finger circumference of the user, and a minimum internal circumference determined to be a predetermined amount smaller than the measured finger circumference of the user.

8. A device according to any preceding claim, wherein the hub comprises a processing module attachable to the user and comprising the processor.

9. A device according to any preceding claim, wherein the hub comprises a connection module attachable to the user and being electrically connectable to the at least one digit unit.

10. A device according to Claim 9, wherein the connection module is connectable to up to at least five digit units.

11. A device according to Claim 9 or Claim 10, wherein the connection module comprises at least one sensor.

12. A device according to any of Claims 9 to 11, wherein each digit unit comprises a digit connector connecting the two digit sensing modules to one another and connectable to the connection module.

13. A device according to Claim 12, wherein the / each digit connector is flexible.

14. A device according to Claim 12 or Claim 13, wherein the / each digit connector is detachable from the connection module.

15. A device according to any of Claims 9 to 14, wherein the processor is configured to detect the number of digit units connected to the connection module.

16. A device according to Claim 15, wherein the processor is configured to identify each digit unit connected to the connection module according to a user’s digit.

17. A device according to any preceding claim, wherein each sensor housing is configured to encase the respective sensor.

18. A device according to any preceding claim, further comprising a splint to which the hub is mounted.

19. A device according to Claim 18, wherein the splint is configured according to a pre-existing splint belonging to the user and modifications for the mounting of the hub.

20. A device according to Claim 18 or Claim 19, wherein the splint comprises a material suitable for additive manufacturing.

21. A device according to any preceding claim, wherein each sensor is a motion capture sensor, optionally comprising an inertial measurement unit.

22. A modular device for tracking hand movements of a user, the device comprising: at least one replaceable digit unit comprising two digit sensing modules, each digit sensing module comprising a sensor, a sensor housing and a digit holder extending from the sensor housing, the digit holder being configured to receive a digit of the user; a hub configured to receive data from the at least one replaceable digit unit; and a processor configured to process data received by the hub.

23. A method of manufacturing a device for tracking hand movements of a user, the method comprising: creating a profile for the user comprising first and second digit dimensions for at least one digit; using an additive manufacturing technique to manufacture first and second digit sensing modules, each digit sensing module comprising a sensor, a sensor housing and a digit holder, each digit holder having an adjustable internal dimension determined according to the first and second digit dimensions in the profile, respectively; and assembling the device comprising a processor, a hub and at least one digit unit comprising the first and second digit sensing modules.

24. A method according to Claim 23, wherein manufacturing each digit sensing module comprises: using a first printer head, configured for printing a first material, to 3D print the sensor housing; using a second printer head, configured for component gripping, to mount a sensor to the sensor housing; using a third printer head, configured for printing a second material, to 3D print the digit holder.

25. A method according to Claim 23 or Claim 24, wherein each digit holder comprises two grips extending from the sensor housing in different directions, eachgrip having a first end coupled to the sensor housing and a second end overlapping the other grip.

26. A method according to Claim 25, wherein 3D printing each digit holder comprises printing each grip directly into connection with the sensor housing, whereby the grips extend vertically from the sensor housing, overlap in an axial direction and the second end of both grips are joined together by a strut.

27. A method according to Claim 25, wherein: 3D printing each digit holder comprises printing each grip such that each grip extends from its first end to its second end in a horizontal direction, the grips overlap in a radial direction and the second end of both grips are movable independently of one another; and the method further comprises coupling each digit holder to a respective sensor housing.

28. A method according to any of Claims 23 to 27, wherein manufacturing the first and second digit sensing modules comprises 3D printing each digit holder such that the adjustable internal dimension comprises a maximum internal circumference that is a predetermined amount larger than a respective digit circumference of the profile, and a minimum internal circumference that is a predetermined amount smaller than the respective digit circumference of the profile.

29. A method according to any of Claims 23 to 28, further comprising using an additive manufacturing technique to manufacture a splint to which the hub is mounted during assembly of the device.

30. A method according to Claim 29, further comprising, prior to manufacturing the splint: 3D scanning a pre-existing splint belonging to the user to create a splint model; and modifying the model for the mounting of the hub; wherein manufacturing the splint comprises 3D printing the splint according to the modified model.

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