GB2549463A

GB2549463A - Wearable sports sensor

Info

Publication number: GB2549463A
Application number: GB1606336.4A
Authority: GB
Inventors: Stroiescu Florin; Duggan Denis
Original assignee: Individual
Current assignee: Individual
Priority date: 2016-04-13
Filing date: 2016-04-13
Publication date: 2017-10-25

Abstract

Wearable sports sensor for determining impact parameters comprising: a first sensor configured to measure kinematics variables relating to acceleration, rotation and orientation of the wearable sports sensor; and a second sensor comprising a plurality of electrodes arranged as a grid of electrodes and configured to sense impact variables comprising location, contact area, magnitude and direction of the impact and wherein the impact variables are sensed based on a variance of an electrical parameter across the grid. Determining the impact parameters is based on a combination of the measured kinematics variables and sensed impact variables. The sports sensor can further include an accelerometer, a gyroscope and a magnetometer. Also disclosed is an impact sensor with a pair of sensor grids 1, 3 arranged on either side of a lamina 2, and an alternative impact sensor comprising piezoelectric elements (16; Fig 5) positioned between a first and a second lamina (Fig 5; 15).

Description

Wearabie sports sensor

Technicai Fieid [0001] The inventions relates to sports sensors and in particular wearable sports sensors for measuring an impact between a body part of the wearer and an external object.

Background Art [0002] For an effective sports sensor, it is desirable to provide as much information, and preferably real-time information as possible regarding a player's interaction with sporting equipment and indeed, interaction with other players. This assists in the evolution of the training and enables comparison between players.

[0003] During training and play, sensors and devices are increasingly worn, be it as wrist watches, integrated into clothing or other sporting equipment, as wearable toys, hearables, glasses, and the like. RFID chips and other communication technology is used to communicate statistics on position, pace, distance travelled and acceleration in real time. Data regarding the players movement, interaction with sporting equipment, interaction with other players is streamed and stored. This data includes timestamps, frequency, amplitude, position on the player’s body part which has a sensor thereon, impact data etc. These measurements are used to assess the player’s performance and the health status of the players.

[0004] It is desirable however, to provide an improved device sensor with additional detail on impact and a player’s interaction with sporting equipment.

Summary of invention [0005] It should be appreciated that all combinations of the foregoing concepts and additional concepts discussed in greater detail below (provided such concepts are not mutually inconsistent) are contemplated as being part of the inventive subject matter disclosed herein. In particular, all combinations of claimed subject matter appearing at the end of this disclosure are contemplated as being part of the inventive subject matter disclosed herein.

[0006] In accordance with the invention there is described a wearable sports sensor for determining a plurality of parameters associated with an impact comprising: a first sensor configured to measure a plurality of kinematics variables relating to acceleration, rotation and orientation of the wearable sports sensor; and a second sensor comprising a plurality of electrodes arranged as a grid of electrodes and configured to sense a plurality of impact variables said impact variables comprising location of the impact, contact area of impact, magnitude of the impact and direction of the impact relative to the contact area of impact and wherein said plurality of impact parameters are sensed based on a variance of an electrical parameter across the grid; and wherein determining the plurality of parameters associated with the impact is based on a combination of the measured plurality of kinematics variables and sensed impact variables.

[0007] The combination of kinematics variables and impact variables provides an improved sensor allowing additional information regarding the effectiveness of the player's interaction with the sports devices in order to assess the evolution of training and to enable comparison between different players. By determining the contact area of impact and the magnitude of impact in combination with the additional variables improved feedback is provided.

[0008] Calculations based on the kinematics variables measured by the first sensor before and after the impact (e.g. acceleration, direction, amplitude) when combined with the sensed impact variables provided by the second sensor, makes the wearable sports sensor able to estimate relative direction, rotation status and spin, relative velocity and other characteristics of an object impacting on the wearable sports sensor, before, during and after the impact.

[0009] The kinematics sensor may comprise one or more accelerometers for measuring said plurality of kinematics variables before, during and after said impact. The kinematics sensor may further comprise one or more gyroscopes and/or one or more magnetometers for measuring said plurality of kinematics variables before, during and after said impact.

[0010] These sensors improve the feedback which is being provided.

[0011] The wearable sensor may further comprise a lamina and wherein the grid of electrodes may comprise a pair of sensor grids arranged on opposing faces of the lamina.

[0012] The electrical parameter may comprise a capacitance measured between an electrode in the first sensor grid of the pair of sensor grids and an electrode in the second sensor grid of the pair of sensor grids and wherein the electrode in the first sensor grid and the electrode in the second sensor grid are axially aligned.

[0013] The plurality of electrodes in each sensor grid may be arranged in a plurality of rows and columns and wherein the electrical parameter may comprise a mutual capacitance measured between the electrode rows and columns at each intersection of the rows and columns, and wherein an electrode in the first sensor grid of the pair of sensor grids and an electrode in the second sensor grid of the pair of sensor grids are axially offset.

[0014] In this way, the mutual capacitance between each row and each column can be measured independently. Thus, a reduced total number of row and column electrodes can be used to provide an increased number of sensing points because the number of sensing points will be the product of the number of columns and the number of rows. In this way, greater areas or better resolutions of sensing points can be achieved with a relatively small number of electrodes.

[0015] The electrical parameter may be periodically sampled.

[0016] The lamina may comprise an insulating substrate [0017] The wearable sensor may further comprise a filter for filtering measurements of the electrical parameters across the pair of sensor grids.

[0018] The filter is used to reduce, and preferably eliminate, electrical noise and measurements which have been generated through the detection of a movement which is not associated with an impact. In other embodiments, multiple filters can be configured, in order to extract information from the sensor in relation to different types of movements. For example, a high pass filter can be used to isolate rapidly changing signals associated with an impact. Additional, a low pass filter can be to isolate slower changing signals associated with a user’s body movements.

[0019] The lamina may comprise a flexible compressible substrate having a plurality of apertures therein for accommodating a reservoir for an inert gas.

[0020] Prior to an impact, the pressure in the gas reservoirs in the apertures maintains two electrodes placed on the opposite sides of the aperture at a preferred stand-by distance, thereby creating a stand-by capacitance between the two electrodes. The inert gas reservoirs are configured as small elastic pillows, which in turn provides elasticity in the distance between the two electrodes. When an impact occurs, the aperture is compressed. As a result, the electrodes on each side of the aperture are pressed together and the distance between the two electrodes is reduced, thereby increasing the mutual capacitance between the electrodes. After the impact, the elasticity of the gas reservoir pushes the electrodes apart, so that they return to being spaced apart by the stand-by distance, thereby decreasing the mutual capacitance of the electrodes to the stand-by value. Preferably, the gas in the reservoirs is an inert gas, in order to protect the electrodes from corrosion. However, other means of protecting the electrodes from corrosion can be used. In this embodiment, the gas need not be inert. Instead, common and inexpensive gasses (e.g. air) can be used.

[0021] The plurality of apertures may be coincident with the intersections of the rows and columns of electrodes.

[0022] At the intersections of the rows and columns of electrodes, the elasticity of each of the apertures helps maintain the spacing between rows and columns of electrodes at the stand-by distance, even when the sensor is bent or movement are happening. Thus the stand-by capacitance is kept relatively constant until an impact occurs.

[0023] Each face of the lamina may further comprise a supporting film on which the sensor grids are disposed.

[0024] The wearable sensor may further comprise a protector film arranged to protect the plurality of electrodes in each sensor grid of the pair of sensor grids.

[0025] In a second embodiment, the wearable sensor may comprise a plurality of piezoelectric elements positioned between a first lamina and a second lamina, and wherein the piezoelectric elements are in electrical contact with the first and second lamina and arranged to sense the location and magnitude of the impact based on a voltage generated across the piezoelectric elements, said voltage being proportional to a deformation of the first and second lamina.

[0026] The use of piezoelectric elements are advantageous as they are easy and cheap to manufacture, they provide big amplitude signals with very well defined frequency domains, and resonance frequency of piezoelectric elements for the dimensions required to implement the wearable sensor device is well above the frequencies of interest in body and sports devices movements. As a result, a measurements taken with a piezoelectric element in the wearable sensor will be taken in the linear area of operation of the piezoelectric element.

[0027] Each of the plurality of piezoelectric elements may be connected to a common ground signal, the wearable sensor further comprising a multiplexer arranged to select between piezoelectric elements.

[0028] The wearable sensor may further comprise an accelerometer configured to measure the acceleration of the wearable sports sensor and wherein the plurality of parameters are further based on the measured acceleration.

[0029] The wearable sports sensor may further comprise a gyroscope configured to measure the angular velocity of the wearable sports sensor and wherein the plurality of parameters are further based on the measured angular velocity.

[0030] The wearable sports sensor may further comprise a magnetometer configured to determine the geographical orientation of the wearable sports sensor and wherein the plurality of parameters are further based on the determined geographical orientation.

[0031] The wearable sensor may further comprise a processing device, arranged to determine the plurality of parameters.

[0032] The wearable sensor may further comprise a data storage device.

[0033] The wearable sensor may further comprise a communication interface.

[0034] The wearable sensor may further comprise a power supply.

[0035] The power supply may be rechargeable and/or replaceable.

[0036] The plurality of parameters associated with the impact comprises at least one of a time of impact, cadence of impact, intensity of impact, energy transfer, off-centre measurement or measurement of energy expenditure of the wearer.

[0037] The wearable sensor may be included in a shoe, a glove, a helmet or any other item of sporting equipment.

[0038] A further embodiment of the invention includes an impact sensor for a wearable sports sensor comprising a lamina having a pair of sensor grids arranged on opposing sides of the lamina, each sensor grid comprising a plurality of electrodes arranged as a grid of electrodes and configured to sense a plurality of impact variables said impact variables comprising location of the impact, contact area of impact, magnitude of the impact and direction of the impact relative to the contact area of impact.

[0039] The electrical parameter may comprise a capacitance measured between an electrode in the first sensor grid of the pair of sensor grids and an electrode in the second sensor grid of the pair of sensor grids and wherein the electrode in the first sensor grid and the electrode in the second sensor grid are axially aligned.

[0040] The plurality of electrodes in each sensor grid may be arranged in a plurality of rows and columns and wherein the electrical parameter comprises a mutual capacitance measured between the electrode rows and columns at each intersection of the rows and columns, and wherein an electrode in the first sensor grid of the pair of sensor grids and an electrode in the second sensor grid of the pair of sensor grids are axially offset.

[0041] The electrical parameter may be periodically sampled.

[0042] The lamina may comprise an insulating substrate.

[0043] The impact sensor may further comprise a filter for filtering measurements of the electrical parameters across the pair of sensor grids.

[0044] The lamina may comprise a flexible compressible substrate having a plurality of apertures therein for accommodating a reservoir for an inert gas.

[0045] The plurality of apertures may be coincident with the intersections of the rows and columns of electrodes.

[0046] Each face of the lamina may further comprise a supporting film on which the sensor grids are disposed.

[0047] The impact sensor may further comprise a protector film arranged to protect the plurality of electrodes in each sensor grid of the pair of sensor grids.

[0048] A further embodiment of the invention includes an impact sensor for a wearable sports sensor comprising a plurality of piezoelectric elements positioned between a first lamina and a second lamina, and wherein the piezoelectric elements are in electrical contact with the first and second lamina are arranged to sense the location, contact area, and magnitude of the impact based on a voltage generated across the piezoelectric elements, said voltage being proportional to a deformation of the first and second lamina.

[0049] Each of the plurality of piezoelectric elements may be connected to a common ground signal, the sports sensor further comprising a multiplexer arranged to select between piezoelectric elements.

Brief description of drawings [0050] Various non-limiting embodiments of the technology described herein will not be described with specific reference to the following figures. It should be appreciated that the figures are not necessarily drawn to scale.

[0051] Figure 1 shows an impact sensor in accordance with an embodiment of the present invention.

[0052] Figure 2 depicts a layered view of the impact sensor in accordance with an embodiment of the present invention.

[0053] Figure 3 shows a plan view of an electrode grid of a wearable sensor in accordance with the invention.

[0054] Figure 4 is an architecture embodiment of a wearable sensor in accordance with the invention.

[0055] Figure 5 shows a layered view of an impact sensor comprising a plurality of piezoelectric elements in accordance with an embodiment of the present invention [0056] Figure 6 depicts a view of a piezoelectric element for use in the embodiment of Figure 5.

[0057] Figure 7 shows a multiplexed version of the measuring area using a grid of piezo electric elements in accordance with the invention.

[0058] Figure 8 shows the kinematics of an impact detected with the wearable sensor in accordance with the invention.

Description of embodiments [0059] The aspects of the technology mentioned above, as well as additional aspects, will now be described in greater detail. The aspects may be used individually, all together or in any combination of two or more, as the technology is not limited in this respect.

[0060] The wearable sports sensor of the present invention is configurable to determine a plurality of parameters associated with an impact. These parameters include: • the time and date when an impact between the wearable sports sensor being worn by the player; • the impact direction; • the exact position or contact area of the impact; • the intensity of the impact; and • the direction of the impact.

[0061] In one configuration the wearable sports sensor may store the plurality of parameters or data for later retrieval. In an alternative configuration the wearable sports sensor may also include a communications interface for real time transmission of the data for external analysis. In an alternative configuration, the parameters may be processed local to the device, however, it will be appreciated that the additional power requirements associated with local processing may be prohibitive to the flexibility and usage of the device. In order to maximise power efficiency any of the embodiments described here may also include power management for the wearable sensor as described further below.

[0062] The wearable sports sensor of the present application provides a combination of impact and kinematics variables to provide improved feedback information regarding a player wearing the sports sensor.

[0063] As shown in Fig. 1 the impact sensor, which is configured to sense a plurality of impact variables, comprises a grid sensor. The grid comprises a lamina, 2. This lamina is an insulating substrate. In an embodiment the insulating substrate is an elastic insulation substrate. The lamina comprises a pair of sensor grids, 1, and 3 arranged on opposing faces of the lamina. The impact variables are determined based on a variance of an electrical parameter across the grid sensor. This electrical parameter may be capacitance or voltage.

[0064] In one configuration, for each point on the sensor grids arranged on opposing sides of the lamina, there is a stored impact variables for an impact in a perpendicular direction to the surface of the sensor. It will be appreciated that having these stored variables a stored reference facilitates a determination of the effectiveness of a strike or effects of a strike. For example, the stored impact variables can be easily compares with the sensed plurality of impact variables to determine if the direction of the impact is perpendicular to the surface of the surface of the sensor. Additionally, a determination can be made as to whether the strike is a straight strike or a spinning effect producing strike. The weighted direction of impact is computed by summing the weighted vectorial orientation of the normal for each of the sensing points with the amplitude of impact for each of the sensing points. Comparing the weighted direction of the impact with a value for acceleration determined using the kinematics variables provides information about the eccentricity of the impact between the wearable sensor device (and in turn a user’s limb or body part where the wearable sensor device is worn) and the object being impacted, thus being possible to evaluate not only the impact amplitude, but also rotation and spinning effects. As used herein, eccentricity refers to a parameter associated a conic section formed in the surface of the wearable device by an impact of an object (e.g. a ball). As such, eccentricity is a measure of how much the conic section deviates from being circular.

[0065] In a first configuration, such as that shown in fig. 1, the electrical parameter determined is capacitance. The grid sensor is formed by the intersection of an angled or perpendicular network of electrodes.

[0066] Using a scan technique the parameters associated with the impact are determined by repeatedly measuring the capacitance of points formed at the intersection of the two networks of electrodes, i.e. formed by the intersection of the sensor grids, 1 and 3 arranged on opposing faces of the lamina. The capacitance may be monitored continuously or monitored only when an impact happens. In one configuration where the capacitance is also measured when no impact happens, the data measured may be stored as offset data further refining the quality of the measurements of impact data.

[0067] The scan technique can be performed in a number of different ways. In one embodiment, a step pulse signal is sent through each of the rows, and the response is measured on each of the columns. The amplitude of the measured signal on each of the columns is proportional to the mutual capacitance between the step pulse row and the column being measured. In another embodiment, a sinusoidal signal is sent through a single row at a time, the amplitude of the signal is measured on each of the columns, and is again, proportional to the mutual capacitance between the row and the column. In both embodiments mentioned above, the role of rows and columns can be reversed. In a third embodiment, each row and columns mutual capacitances are measured via sampling the resonant frequency of a self-oscillating oscillator. Other methods of measuring the mutual capacitance in the points of intersection between a row and columns of a matrix will be apparent to the skilled practitioner and may be utilized in different embodiments of the wearable sensor device.

[0068] As can be seen from Figure 1, the bottom sensor grid, i.e. the grid on the underside of the lamina is placed at an angle (90 degrees in Figure 1) relative to the top or grid on the topside of the lamina. It will be appreciated that while described as top and bottom the orientation of the grid will vary depending on where on the wearer it is positioned. For example, the sensor grids and lamina may be vertically orientated or at an angle as opposed to the horizontally orientation shown in figure 1. The electrodes in each sensor grid are axially aligned. In an alternative configuration the electrodes in each sensor grid may be axially offset.

[0069] During an impact, the lamina or insulation substrate, 2 is squeezed or compressed. It will be appreciated that this increases the capacitance in the contact area of impact. This contact area of impact corresponds to the area of the wearable sensor which is squeezed or compressed during the impact. It will further be appreciated that the capacitance measured will be higher when measured between the points of intersection of the grid which are closer the centre or point of impact. This measured capacitance can be used to determine the impact variables. The impact variables include, but are not limited to the location of the impact, contact area of the impact, magnitude of the impact and direction of the impact relative to the contact area of impact.

[0070] The insulating substrate 2 can be formed using an elastic compressible foam, or other flexible material. In the configuration shown in Rg. 2 the insulation substrate comprises a special geometry employing pockets at each of the intersection points. The insulation substrate includes a plurality of apertures and these apertures are arranged to accommodate reservoirs or pockets. Alternatively, the insulation substrate may be formed with the reservoirs or pockets integral thereto. These pockets, in either configuration, are filled with an inert gas or alternatively filled with a gelatinous substance. In the configuration shown in Figure 2, the insulating lamina 2 includes an aperture or hole 8 therein. This hole is configured to accommodate a pocket or reservoir as described above. The insulating lamina is preferably flexible but non-compressible. Sensor grids 1 and 3 are arranged on opposing faces of the lamina 2. The sensor grids shown in figure 2 have a protective outer layer, 4, 7 and a supporting film 5, 6. These additional layers provide support and protection for the grid.

[0071] As shown in figure 3 the intersections of the sensor grids preferably align with the apertures or holes 8 in the lamina 2.

[0072] The mutual capacitance between any of the two wires, one on the top layer and one of the bottom layer is described as follows: 1. C = ERxA/d - where C is the mutual capacitance, Er is the permittivity of the insulation medium between the electrodes, A is the mutual surface of the electrodes, and d is the distance between the electrodes.

[0073] It will be appreciated that this equation is approximate. It will be appreciated that other factors such as the non-homogenous insulation medium between the electrodes and the wire rather than plate shape will alter the equation. What is evident from the equation above is the inverse proportionality between the capacitance and the distance between the electrodes.

[0074] The mutual capacitance between the electrodes slowly varies due to motion artefacts, humidity in the field and other noise factors, but it varies fast due to impacts.

[0075] In accordance with the invention, further filtering may be applied to filter out the fast variance from the slow variance to extraction valid data. While not described herein it will be appreciated that both hardware and software filtering techniques or a combination of the two may be applied. Filtering may include noise filtering to remove background noise. For example, noise may be generated by external factors, like motion artefacts, humidity, and internal factors such as electronic noise.

[0076] An embodiment of the wearable sensor including the impact sensor as described in relation to figures 1 to 3 is shown in fig. 4. The wearable sensor 9 is connected to a communication or sensor interface 10. This communication interface is arranged to transmit the measured capacitances of the grid or individual sensor points, and additional kinematics data to a microcontroller 11, or interfacing with a communication device 12 to transmit the data/variables or parameters and events to an external computing device.

[0077] The external computing device may include a computer, smartphone, any other user interface device or data aggregator.

[0078] Data may be stored on a data storage device 13. The wearable sensor is also provided with a power supply 14. It will be appreciated that the data storage may be local to the wearable sensor or remote therefrom. The data storage may be integrated with the external computing device.

[0079] Further the microcontroller 11 may be integral to the wearable sensor or remote therefrom, for example integrated with the external computing device.

[0080] As mentioned above, where the sensor 9 is configured as a grid and the fast variance of the capacitance of the points where the impact occurs is sampled by the sensor interface 10. This sampling is then transferred to the microcontroller 11.lt will be appreciated that a sensor for measuring kinematics variables is also included in the sensor. This kinematics sensor is further described below in relation to Fig. 8.

[0081] In a configuration where the microcontroller is local to the sensor, the microcontroller may apply filtering, detection and decision algorithms to extract the useful information. The microcontroller 11 may store the data in the data storage device 13 and/or transmit live data via the communication device 12 to the external computing device. The microcontroller is preferably a low power device.

[0082] It will be appreciated that the communication device 12 can be used as well for transmitting the stored data on data storage device 13 to a computer, smartphone, any other user interface device or data aggregator, after the data collection session happens. The communication can be wired (USB, Ethernet, etc.) or wireless (Bluetooth, Bluetooth Low Energy, Zigbee, Wi-Fi, UWB, etc.). In a preferred configuration, the wireless interface permits the live data streaming. In an alternative configuration, the provision of a USB connection would facilitate re-charging of the device where the power supply is re-chargeable. In an alternative configuration, the power supply may be a battery or removable power source.

[0083] The data storage device 13 may comprises any non-volatile memory and may be integral or removable. For example, the data storage device may include a flash memory, an SD card or the like.

[0084] As mentioned above, the power supply 14 may include a battery.

Additional battery management (not shown) and/or charging circuitry (not shown) may be provided. The battery management circuitry appreciably will enable a wearer or user to monitor the power level of the battery or other power source. This will facilitate recharging or allow an alert to be generated to change the batter or power source. Further this battery management may facilitate altering the power source, for example from an internal source to an external source. In addition, battery management circuitry may be used to monitor a change from a wired (e.g. via USB) charging system to a wireless charging system for example a wireless charger in a shoe, etc. The power supply may also include an energy harvester, for example a piezoelectric, electromagnetic or thermoelectric charger. The energy harvester may collect energy from a player’s movement. In an embodiment, this may be used to charge a power supply local to the wearable sensor.

[0085] An alternative sensor 9 is shown in figures 5 and 6. This alternative sensor may be used with the configuration of Figure 4 as an alternative to the capacitive sensor arrangement of figures 1 to 3. In the configuration shown, the impact sensor comprises a plurality of piezoelectric elements 16 positioned between a first lamina 15 and a second lamina 15. The lamina may be formed from a flexible material, synthetic, textile or leather. Piezo electric elements, for example small pills of piezoelectric material 16 are maintained in electrical contact with the first and second lamina. In the configuration shown in figure 6, the piezoelectric elements have two opposing metalized faces. These opposing faces are electrodes. The piezoelectric elements are connected via perpendicular or aligned wires. The piezoelectric elements are grouped in a mesh.

[0086] On impact, the piezoelectric material in the pills or elements generates a voltage proportional to the deformation or compression of the impact sensor. An electrical signal is generated which is representative of the impact, i.e. following the shape and amplitude of the deformation of the wearable sensor device caused by the impact. In particular, the impact pressure is usually higher in the center of impact and lower when measuring it further away from the center of impact, thus, the measured amplitude of the electric signal will be highest for the elements in the center of impact, and the measured amplitude will progressively diminish for each elements with increasing distance from the center of the impact.

In this way, the measured amplitudes of the electric signal on the various piezoelectric elements measures the ‘shape’ of the impact pressure.

[0087] Alternative arrangements of the piezoelectric elements are also envisaged. For example in Figure 7, each element is connected to a common ground signal through one electrode. Each element is also connected to a multiplexer through the second electrode. The electrodes correspond to the opposing metalized faces as shown in Figure 6. This is then fed to an analog to digital converter, ADC. From the ADC the output signal travels to a measuring circuit, (not shown). In either configuration, as shown in Figures 5 or 7, additional filtering can be added in order to avoid motion artefacts and only the useable signal to reach the measuring circuit. In the configuration of Figure 7, at impact, the piezoelectric material in the piezoelectric elements 16 generates a voltage proportional with the deformation. The electrical field generated again is representative of the impact, i.e. the electrical field generated is following the shape and amplitude of the impact.

[0088] The kinematics of the impact detected by the combination between the kinematics sensor included in the device and the impact sensor surface is depicted in figure 8. The impact sensor material detects the location and the area of the impact like ellipses of high level voltage around the centre of the impact 25 and lower voltages on areas away from the centre of impact 26. The direction of the averaged normal on the surface 21, precalculated for each sensor element area, is compared with the data coming from the accelerometer, which, at the moment of impact, will change initial movement direction 22 to the new direction 23, through the speed variation 24, which produces a proportional measurement as the acceleration of the device due to the impact. The difference in direction between the two vectors is calculated and indicates how off-centre the strike or impact is. It will be appreciated that other metrics and sensors, like gyroscopes and magnetometers may be used so as to obtain a better definition of the measured impact. The kinematics sensor may comprise one or more accelerometers. The accelerometer in a preferred configuration is a tri-axial accelerometer. It will be appreciated that such an accelerometer signals the appearance of an impact and data therefrom is useable to determine a kind of impact. Further, the kinematics sensor may comprise one or more gyroscopes. The gyroscope in a preferred configuration is also tri-axial. It will be appreciated that the output of the gyroscope may be used to show the angular velocity of the device and facilitate in the calculation of pre-, during and post kinematics data.

[0089] Further, the kinematics sensor may comprise one or more magnetometers. The magnetometer, preferably tri-axial, facilitates the indication of the geographical orientation of the device. It will be appreciated that such a device is power hungry. Alternatively, a switchable power source to meet the power requirements of this device may be provided.

[0090] It will be appreciated that the information obtained from the kinematics sensor in combination with the impact sensor augments the quality of the information determined.

[0091] The measured parameters may include, but not limited to: - The time and cadence of hits; - Impact intensity, (the modulus of the acceleration measured by the accelerometer); - Energy transfer to the object hit, due to the area and amplitude of the voltages measured on the sensor surface; - Off-centre effect due to the difference in direction between the normal on the centre of the impact area on the sensor surface and the acceleration during the hit; - Indirect energy expenditure of the player during the movements measured by the accelerometer.

[0092] This wearable sensor in accordance with the invention will enable the trainer and / or the player that has to hit a sports device or another player during the play, to determine the time, position, intensity and other parameters of the strike. With these recorded parameters the trainer/player can assess the effectiveness of the training, compare the way the players are performing. The wearable sensor in accordance with the invention may be included in a sports or fitness shoe; boxing gloves; protection helmets both for commercial and sports applications; fencing costumes or other item of sporting equipment or clothing.

[0093] The words “comprises/comprising” and the words “having/including” when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. It is appreciated that certain features of the invention, which are for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity described in the context of a single embodiment, may also be provided separately or in any suitable combination.

Claims

Claims Claim 1. A wearable sports sensor for determining a plurality of parameters associated with an impact comprising: a first sensor configured to measure a plurality of kinematics variables relating to acceleration, rotation and orientation of the wearable sports sensor; and a second sensor comprising a plurality of electrodes arranged as a grid of electrodes and configured to sense a plurality of impact variables said impact variables comprising location of the impact, contact area of impact, magnitude of the impact and direction of the impact relative to the contact area of impact and wherein said plurality of impact parameters are sensed based on a variance of an electrical parameter across the grid; and wherein determining the plurality of parameters associated with the impact is based on a combination of the measured plurality of kinematics variables and sensed impact variables. Claim
2. The wearable sports sensor according to claim 1 wherein the kinematics sensor comprises an accelerometer for measuring said plurality of kinematics variables before, during and after said impact. Claim
3. The wearable sensor according to claim 2 further comprising: a gyroscope for measuring said plurality of kinematics variables before, during and after said impact; a magnetometer for measuring said plurality of kinematics variables before, during and after said impact; or a gyroscope and a magnetometer for measuring said plurality of kinematics variables before, during and after said impact. Claim
4. The wearable sensor of claim 1 or 2 further comprising a lamina and wherein the grid of electrodes comprises a pair of sensor grids arranged on opposing faces of the lamina. Claim
5. The wearable sensor of claim 4 wherein the electrical parameter comprises a capacitance measured between an electrode in the first sensor grid of the pair of sensor grids and an electrode in the second sensor grid of the pair of sensor grids and wherein the electrode in the first sensor grid and the electrode in the second sensor grid are axially aligned. Claim
6. The wearable sensor of claim 4 wherein the plurality of electrodes in each sensor grid are arranged in a plurality of rows and columns and wherein the electrical parameter comprises a mutual capacitance measured between the electrode rows and columns at each intersection of the rows and columns, and wherein an electrode in the first sensor grid of the pair of sensor grids and an electrode in the second sensor grid of the pair of sensor grids are axially offset. Claim
7. The wearable sensor of claim 4 wherein the electrical parameter is periodically sampled. Claim
8. The wearable sensor according to any of claims 4 to 7 wherein the lamina comprises an insulating substrate Claim
9. The wearable sensor of any of claims 4 to 8 further comprising a filter for filtering measurements of the electrical parameters across the pair of sensor grids. Claim
10. The wearable sensor of any of claims 4 to 9 wherein the lamina comprises a flexible compressible substrate having a plurality of apertures therein for accommodating a reservoir for an inert gas. Claim
11. The wearable sensor of claim 10 wherein the plurality of apertures are coincident with the intersections of the rows and columns of electrodes. Claim
12. The wearable sensor of any of claims 4 to 11 wherein each face of the lamina further comprises a supporting film on which the sensor grids are disposed. Claim
13. The wearable sensor of any of claims 4 to 12 further comprising a protector film arranged to protect the plurality of electrodes in each sensor grid of the pair of sensor grids. Claim
14. The wearable sensor of claim 1 or 2 wherein the second sensor comprises a plurality of piezoelectric elements positioned between a first lamina and a second lamina, and wherein the piezoelectric elements are in electrical contact with the first and second lamina and arranged to sense the location and magnitude of the impact based on a voltage generated across the piezoelectric elements, said voltage being proportional to a deformation of the first and second lamina. Claim
15. The wearable sports sensor of claim 14 wherein each of the plurality of piezoelectric elements are connected to a common ground signal, the sports sensor further comprising a multiplexer arranged to select between piezoelectric elements. Claim
16. The wearable sports sensor according to any previous claim further comprising a gyroscope configured to measure the angular velocity of the wearable sports sensor and wherein the plurality of parameters are further based on the measured angular velocity. Claim
17. The wearable sports sensor according to any previous claim further comprising a magnetometer configured to determine the geographical orientation of the wearable sports sensor and wherein the plurality of parameters are further based on the determined geographical orientation. Claim
18. The wearable sensor of any previous claim further comprising a processing device, arranged to determine the plurality of parameters. Claim
19. The wearable sensor of any previous claim further comprising a data storage device. Claim
20. The wearable sensor of claim 14 or 15 further comprising a communication interface. Claim
21. The wearable sensor of any previous claim further comprising a power supply. Claim
22. The wearable sensor of claim 21 wherein the power supply is rechargeable and/or replaceable. Claim
23. The wearable sensor according to any previous claim wherein the plurality of parameters comprises at least one of a time of impact, cadence of impact, intensity of impact, energy transfer, off-centre measurement or measurement of energy expenditure of the wearer. Claim
24. The wearable sensor as described herein with reference to the appended drawings. Claim
25. A shoe comprising the wearable sensor according to any of claims 1 to 24. Claim
26. A glove comprising the wearable sensor according to any of claims 1 to 24. Claim
27. A helmet comprising the wearable sensor according to any of claims 1 to 24. Claim
28. An impact sensor for a wearable sports sensor comprising a lamina having a pair of sensor grids arranged on opposing sides of the lamina, each sensor grid comprising a plurality of electrodes arranged as a grid of electrodes and configured to sense a plurality of impact variables said impact variables comprising location of the impact, contact area of impact, magnitude of the impact and direction of the impact relative to the contact area of impact. Claim
29. The impact sensor of claim 18 wherein the electrical parameter comprises a capacitance measured between an electrode in the first sensor grid of the pair of sensor grids and an electrode in the second sensor grid of the pair of sensor grids and wherein the electrode in the first sensor grid and the electrode in the second sensor grid are axially aligned. Claim
30. The impact sensor of claim 28 or 29 wherein the plurality of electrodes in each sensor grid are arranged in a plurality of rows and columns and wherein the electrical parameter comprises a mutual capacitance measured between the electrode rows and columns at each intersection of the rows and columns, and wherein an electrode in the first sensor grid of the pair of sensor grids and an electrode in the second sensor grid of the pair of sensor grids are axially offset. Claim
31. The impact sensor of claim 30 wherein the electrical parameter is periodically sampled. Claim
32. The impact sensor according to any of claims 28 to 31 wherein the lamina comprises an insulating substrate. Claim
33. The impact sensor of any of claims 28 to 32 further comprising a filter for filtering measurements of the electrical parameters across the pair of sensor grids. Claim
34. The impact sensor of any of claims 30 to 33 wherein the lamina comprises a flexible compressible substrate having a plurality of apertures therein for accommodating a reservoir for an inert gas. Claim
35. The impact sensor of claim 34 wherein the plurality of apertures are coincident with the intersections of the rows and columns of electrodes. Claim
36. The impact sensor of any of claims 28 to 35 wherein each face of the lamina further comprises a supporting film on which the sensor grids are disposed. Claim
37. The impact sensor of any of claims 28 to 36 further comprising a protector film arranged to protect the plurality of electrodes in each sensor grid of the pair of sensor grids. Claim
38. An impact sensor for a wearable sports sensor comprising a plurality of piezoelectric elements positioned between a first lamina and a second lamina, and wherein the piezoelectric elements are in electrical contact with the first and second lamina are arranged to sense the location, contact area, and magnitude of the impact based on a voltage generated across the piezoelectric elements, said voltage being proportional to a deformation of the first and second lamina. Claim
39. The impact sensor of claim 38 wherein each of the plurality of piezoelectric elements are connected to a common ground signal, the sports sensor further comprising a multiplexer arranged to select between piezoelectric elements. Claim
40. The impact sensor as described herein with reference to the appended drawings.