EP3142757B1

EP3142757B1 - Wearable device comprising one or more impact sensors

Info

Publication number: EP3142757B1
Application number: EP15732369.2A
Authority: EP
Inventors: Marco MIGLIORATI; Samuele GRILLO; Franscesco CASTELLI-DEZZA
Original assignee: Italian Fight Wear Srl
Current assignee: Italian Fight Wear Srl
Priority date: 2014-05-15
Filing date: 2015-05-15
Publication date: 2019-04-17
Anticipated expiration: 2035-05-15
Also published as: HRP20191037T1; JP2017532461A; EP3142757A1; US20170157488A1; WO2015173776A1

Description

The present invention relates to a wearable device as claimed in claim 1 comprising one or more impact sensors and at least one unit transmitting the detected signals to a remote station.
This type of devices are known and used for measuring performances of athletes, above all in the martial art field.
The document US 5,723,786 describes a boxing glove wherein an impact measuring device is incorporated which comprises a fluid bag in the impact area of the glove, which bag is connected by a tube to a pressure sensor provided in the cuff.
The document US 4,761,005 describes a device for generating an analog output signal indicative of an impact to a transducer.
The transducer may be mounted on protective equipment used in various martial art fields, such as boxing gloves, shin guards, vests and it is of the piezoelectric type and it is indicative of the amount of deformation.
The transducer is composed of a piezoelectric film coupled to a deformable material, or it is inserted between two layers of deformable material, and the output signal is generated on the basis of the impacts on the deformable material.
The transducer may be connected to a remote receiver and transmitter for providing an indication of the impact to a remote station.
Therefore the known devices are part of the protective equipment of the athlete, for example they are composed of boxing gloves.
This condition has some drawbacks.
Firstly the boxing glove by its nature is subjected to many and repetitive stresses even of considerable level and therefore it is subjected to wear above all in the external part which can be subjected to tearing or other similar damages.
Therefore, over time, the boxing glove has to be replaced, and all the sensor part incorporated therein has to be necessarily replaced with it. This causes the use of such type of devices to be expensive, which currently are not widely spread and do not have a suitable success in the market.
Secondly, it is not rare for an athlete to perform more than one martial art, and for each martial art a different type of boxing glove is necessary.
In this case, in order to use the same type of sensors in the different martial arts, the athlete must necessarily have a plurality of specific gloves, each pair of gloves comprising the same type of sensors and components, with a substantial increase in costs and a useless redundancy in the components themselves.
Moreover the known devices have a single impact sensor and therefore they do not allow the type of impact to be finely detected, providing more detailed information above all as regards the geometry of the impact.
The fact of providing a single sensor, moreover, can lead to inaccuracies in the measurement, for example a wrong calibration or due to too much high tolerances in the detection.
Therefore there is the unsatisfied need in the prior art for a device allowing costs to be considerably reduced, which is usable in different martial arts and that contemporaneously guarantees a good accuracy and reliability of the impact measurement.
The document US 2006/0047447 A1 describes a gauze bandage provided with monitoring components, that wraps the hand of the athlete. This arrangement does not allow for a correct positioning of the sensors, because the gauze bandage needs to be wrapped around the hand of the athlete and a different tensioning of the bandage during the wrapping can lead to completely different positions of the sensors. The athlete must take an excessive cure on positioning the bandage, because an incorrect positioning of the sensor can lead to results that are distorted, even to a great extent.
The present invention overcomes the drawbacks of the known devices by providing a device such as described hereinbefore, which is composed of an inner glove wearable under a martial art glove.
Thus the inner glove or glove liner can be used with different types of gloves or boxing gloves.
This allows the same inner glove to be reusable even when the glove has to be replaced, and it allows only one inner glove to be used with different specific gloves for different martial arts.
The inner glove allows for a univocal and precise positioning of the sensors, when the athlete wears it.
The term inner glove means a glove with a thickness lower than 4 mm, composed of stretch or non-stretch fabric, made of any material, such as cotton or synthetic fibers.
It is possible to use at least partly engineered fibers, which incorporate several types of sensors therein.
According to one embodiment one or more inertial sensors are provided.
The inertial sensors can comprise accelerometers and gyroscopes in combination or as an alternative with each other.
This allows speeds and linear and angular accelerations to be measured without the need of an external reference.
According to a further embodiment there are provided one or more biometric sensors.
Biometric sensors can be of any type, for example heart beat sensors, body temperature sensors, blood pressure sensors, oxygen saturation sensors, perspiration sensors.
Usually the athlete under the martial art gloves wears, as an alternative to the inner glove, wraps which are wrapped around the hand and the wrist.
Therefore biometric sensors cannot be mounted directly on the glove, since the inner glove or the wraps prevent them from directly contacting the athlete skin.
This would make it necessary to use wires for reaching an area of the forearm not covered by the wraps or by the inner glove, such area being clearly disadvantageous with respect to the wrist for example in the case of detection of the heart beat.
In the device of the present invention, on the contrary, biometric sensors are advantageously arranged on the inner glove, which is in direct contact with the athlete skin, guaranteeing an accurate detection of the biometric values desired to be monitored.
According to one embodiment, one or more of the fingers of the inner glove are truncated, such that the inner glove, in the worn condition, covers only the first phalange of one or more of the corresponding fingers of the user.
This strengthens the flexibility concept characterizing the device of the present invention, since thus the inner glove can be worn with the glove of any martial art, also those martial arts that provide an open-fingered glove, such as for example MMA (Mixed Martial Arts).
According to a further embodiment said impact sensors are of the piezoelectric type.
As an alternative or in combination impact sensors can be of the capacitive type or of another type, for example strain gauges.
According to a further embodiment there is provided a plurality of said impact sensors, which impact sensors are arranged in such a manner to form an array.
Thus information about the impact are detected from different positions such to perform more accurate evaluations on the impact and such to have a more accurate estimation of the detected values and of their correctness.
According to an improvement there are provided one or more impact sensors at the forefinger, middle finger, ring finger and little finger respectively.
Thus it is possible to cover with the sensors a detection area that is distributed on all the impact area of the fist.
It is further possible to make an evaluation of the impact for each individual finger, allowing the geometrical characteristics of the impact to be reconstructed.
In a further improvement there are provided three sensors for each one of said fingers.
Thus the array of sensors is composed of 12 sensors, although more or fewer sensors are possible, also distributed in a non-homogeneous manner on the fingers.
It has been found that an array of 12 sensors has good dimensions to be mounted on the inner glove and to guarantee a sufficiently detailed detection of the impact.
In an advantageous embodiment only two impact sensors are provided for each finger.
Advantageously there are provided four sensors on the knuckles, that is on the area more involved in the impact.
In one variant embodiment there are provided 8 sensors, two sensors being provided for each finger.
In a further embodiment, at least one sensor is placed on the glove portion corresponding to the back of the hand.
This allows hits on the back of the hand to be detected and measured.
According to a further embodiment the unit transmitting the detected signals is set such to transmit the signals to the remote station in real-time.
This has the great advantage of allowing the detected signals to be used for supplementing television shooting of the matches with real-time data of the athlete performances.
The present invention further relates to a wearable device comprising one or more impact sensors and at least one unit transmitting the detected signals to a remote station, which device comprises a plurality of said impact sensors, which impact sensors are arranged such to form an array.
The device advantageously is a part of the protective equipment of an athlete, such as for example boxing gloves, shin guards, vests, knee-pads, elbow guards, helmets, shoes.
According to one embodiment the device is composed of a glove or an inner glove and it comprises one or more of the characteristics listed above. Even if the characteristics listed above are described with reference to an inner glove, they can be considered valid for a glove or a boxing glove.
The signals generated by the accelerometer can be used to obtain an estimation of velocity in the three directions. Theoretically it is possible to obtain the velocity from the acceleration, by performing the following integration: $v (T) = \int_{- \infty}^{T} a (t) dt$
However, the measures of the acceleration generated by the accelerometer have some offsets that are not constant in time and that would lead the integral to diverge. In order to obviate to this problem, the integral is approximated with a low-pass filter, so to diminish the drift problems. Furthermore, in order to diminish these effects at low frequencies, also a high-pass filter is applied.
Anyway, this estimation is not sufficiently reliable for the hand's movement during a hit. Without an estimation of the trajectory in the three dimensions, in fact, it is not possible to remove from the acceleration the components due to the centrifugal forces and the change of gravity given by changes of orientation of the device.
An accurate estimation of the trajectory would be possible only with an IMU with nine degrees of freedom, which would increase exaggeratedly the cost, weight and complexity of the device.
In order to obviate to these problems, the present invention relate also to a method as claimed in claim 12 for estimating the velocity starting from the velocity lost during the hit. Thanks to this approach, it is possible to ignore the velocity variations before the impact and, therefore, also the problems related to them.
This method of measuring the power of an impact of a wearable device comprising one or more impact sensors and at least one accelerometer, comprises the following steps:

a) acquiring signals of acceleration from the accelerometer;
b) obtaining the velocity vector along a predetermined direction by integrating the acceleration signals;
c) obtaining the force vector of the impact from the impact sensors, said sensors being positioned in such a way that the force vector is along the said predetermined direction of the velocity vector;
d) calculate the power of the impact as the dot product of the force vector and the velocity vector.

The energy of each impact is also calculated from the power.
According to an advantageous embodiment the velocity vector is taken into account for the calculation of the power of the impact only in the time period when said velocity is decreasing during the impact.
This allows to overlook the velocity before the impact, and to obtain a more precise calculation.
According to an embodiment, a low-pass filter is applied to the acceleration signal before step b).
According to a further embodiment, wherein a high-pass filter is applied to the acceleration signal before step b).
These and other characteristics and advantages of the present invention will be more clear from the following description of some non limitative embodiments shown in the annexed drawings wherein:

Figs. 1 to 3 are different views of the device;
Fig. 4 is a functional block diagram of the device;
Fig. 5 shows the measured velocity;
Figs. 6 to 8 show the velocity, force and power of an impact;
Fig. 9 shows the calculated energy.

Figure 1 shows the wearable device of the present invention, which is composed of an inner glove 1 wearable under a martial art glove.
The inner glove 1 is shown in the worn condition and with the user hand closed in a fist.
The fingers of the inner glove 1 are truncated, such that in the worn condition the inner glove 1 covers only the first phalange of the user's fingers.
As an alternative it is possible to provide an inner glove with non-truncated fingers, or with the fingers truncated such to cover also the second phalange of the user's fingers.
The inner glove 1 is composed of stretch or non-stretch fabric, made of any material, such as cotton or synthetic fibers.
On the inner glove 12 impact sensors 2 are fastened arranged such to form an array.
There are provided three impact sensors 2 at the forefinger, middle finger, ring finger and little finger respectively, such to define a detection area that is distributed all over the impact area of the fist, one sensor of which being placed on the knuckle.
According to one embodiment the impact sensors 2 are of the piezoelectric type, but they can be, as an alternative or in combination, force sensing resistors (FSR) or of the capacitive type or of other type.
Figure 2 shows a view of the back of the hand with the inner glove 1 in the worn condition, wherein the array of impact sensors 2 is visible placed on the truncated fingers of the forefinger, middle finger, ring finger and little finger.
The device comprises an inertial sensor 3 or inertial measurement unit, which can comprise one or more accelerometers and/or gyroscopes in combination or as an alternative to one another.
For example it is possible to provide three accelerometers and three gyroscopes in order to produce a three-dimensional measurement of the linear and angular accelerations.
Figure 3 shows a view of the hand palm with the inner glove 1 in the worn condition, wherein a biometric sensor 4 is visible, advantageously placed in the wrist area.
It is possible to provide only one or more biometric sensors, which can be of any type, for example heart beat sensors, body temperature sensors, blood pressure sensors, oxygen saturation sensors, perspiration sensors.
Sensors 2, 3 and 4 are connected to a central processing unit 5 which comprises a unit transmitting the detected signals to a remote station.
The processing unit 5 preferably is composed of a flexible electronic card, in order to be better secured to the inner glove 1, which acts as a support, which electronic card comprises a microprocessor and a plurality of electronic components conditioning the input signals. However, in a different embodiment the electronic card is non-flexible.
All this can be covered by a layer of resin or the like such to prevent components from being unwelded during the use.
As an alternative or in combination a curing process can be used for insulating the components.
The connection is guaranteed by electric wires, preferably housed into coulisses formed on the inner glove 1.
Advantageously, the wires have a zigzag pattern such to have a length enough for guaranteeing a connection without tearing or damages for any type of deformation and elongation to which the inner glove 1 or a part thereof is subjected during the use.
The processing unit 5 is powered by an electric energy source, preferably a battery.
The battery can be housed in a pocket formed in the inner glove 1 which can be accessed from the outside to allow the battery to be replaced once it is depleted.
As an alternative the battery is rechargeable, for example it is composed of a lithium-ion battery or a lithium-ion polymer battery or a nickel-metal hydride battery (NiMH) or another type, there being provided a recharging circuit comprising a connector to an external power supply, such recharging circuit being outside of or integrated with respect to the processing unit 5.
As an alternative, the recharging circuit can comprise an inductive charging system, which comprises a receiver coupled to the battery and which is arranged to communicate with a transmitter coupled with an external electric source. Both the transmitter and the receiver are provided with one or more coils, in order to perform inductively this wireless energy transfer, by simply bring near the transmitter and the receiver. Preferably the standard Qi is used. However, other standards or protocols can be used.
The device can be switched on or off by means of a switch. The switch can comprise a very thin button, a tactile button, which is sensitive to pressure like the pressure sensors, or a magnetic switch, which can be activated or deactivated by means of a small magnet.
In another embodiment, the device is switched in stand-by consequently to an inactivity period as detected by the accelerometer, and can be switched on again once a movement is detected.
Figure 4 shows a functional block diagram of the device, wherein impact sensors 2, inertial sensors 3 and biometric sensors 4 are visible, connected to the central processing unit 5.
The data detected by the different sensors are sent to the central processing unit 5, which comprises a unit 51 transmitting the detected signals to a remote station.
The unit 51 transmitting the detected signals is configured such to transmit the signals to the remote station in real-time, such that the data can be displayed during television live broadcasts of the matches.
The communication between the unit 51 transmitting the detected signals and the remote station can occur according to any protocol, preferably according to the ZigBee protocol or Bluetooth protocol.
The central processing unit 5 comprises an average unit 50, which averages two or more of the signals detected by the impact sensors 2 and it sends the calculated values as an alternative or in combination with the signals detected by the impact sensors 2.
In one embodiment all the signals detected by the impact sensors 2 are averaged for obtaining a single calculated signal indicative of all the impact sensors 2.
According to a variant embodiment the signals about each finger are averaged, therefore 4 signals are obtained indicative of each finger.
The central processing unit 5 further comprises a unit measuring the residual charge of the battery 54, which generates an alarm signal when the residual charge goes below a predetermined threshold.
The signal can be sent to the remote station from the unit 51 transmitting the detected signals or it is possible to provide signalling means for the user, such as a buzzer or a LED.
The central processing unit 5 comprises a patient health alarm unit 55, which compares the signals received from the biometric sensors 4 with threshold values, which can be predetermined or set by the user, and it generates an alarm signal if the detected values exceed the threshold values.
The central processing unit 5 further comprises a unit 56 recognizing the given punch, which processes the signals generated by the inertial sensors 3 for defining known patterns referable to particular moves of the athlete.
The data are further compared with the signals coming from the impact sensors 2 in order to estimate the punch given by the athlete.
All the received or generated signals can be stored by the central processing unit in a local storage unit 52, which is accessible by means of an input/output unit 53, such as a USB port or a slot for a flash card or similar non volatile storage devices.
The signals generated by the accelerometer can be used to obtain an estimation of velocity in the three directions. The velocity is obtained from the acceleration, by performing the following integration: $v (T) = \int_{- \infty}^{T} a (t) dt$
and applying a low-pass filter and a high-pass filter.
Furthermore, the velocity is estimated starting from the velocity lost during the hit. Thanks to this approach, it is possible to ignore the velocity variations before the impact and, therefore, also the problems related to them.
Figure 5 shows the velocity measured for two impacts. As can be seen, the velocity is always ignored except for during the impacts.
Once the velocity is calculated from the acceleration, as explained above, it is possible to calculate and plot the power of an impact, using the following formula: $P (t) = \vec{F} (t) \times \vec{v} (t)$
where × is the dot product of the force vector and the velocity vector.
Figure 6, 7 and 8 show respectively the velocity, force and power of the same impact, as measured and calculated above.
The direction of interest is obviously that with versor coming out from the fingers. The force measured by the sensors, thanks to their positioning, is already the component in that direction, and it will be sufficient to multiply it with the direct velocity in the same way to obtain an estimation of the power.
The energy is linked to the power by the following integration: $E = \int_{t 1}^{t 2} P (t) dt$
where t1 and t2 are the start and end instants of the hit.
In this way the energy of every single hit is calculated from the power, as can be seen in Figure 9.

Claims

Wearable device comprising a plurality of impact sensors (2), at least one inertial sensor (3), the said sensors (2, 3) being connected to a central processing unit (5) provided with a transmitting and receiving unit (51) able to communicate with a remote station, the said impact sensors (2) being disposed, on the surface of an inner glove wearable under a martial art glove, in such manner so as to form an array.
Device according to claim 1, wherein there are provided one or more biometric sensors (4), connected to the central processing unit.
Device according to claim 1 or 2, wherein one or more of the fingers of the inner glove (1) are truncated, such that the inner glove (1), in the worn condition, covers only the first phalange of one or more of the corresponding fingers of the user.
Device according to anyone of the preceding claims 1 to 3, wherein said impact sensors (2) are of the piezoelectric type.
Device according to anyone of the preceding claims 1 to 4, wherein there are provided one or more impact sensors (2) at the forefinger, middle finger, ring finger and little finger respectively.
Device according to claim 5, wherein there are provided three impact sensors (2) for each one of said fingers.
Device according anyone of the preceding claims 1 to 6, wherein the unit (51) transmitting the detected signals is set such to transmit the signals to the remote station in real-time.
Device according to one or more of the preceding claims, wherein the device is powered by a rechargeable battery, there being provided a recharging circuit comprising an inductive charging system.
Device according to one or more of the preceding claims, wherein said one or more inertial sensors comprise an accelerometer and the device is switched in stand-by consequently to an inactivity period as detected by the accelerometer, and the device can be switched on again once a movement is detected.
Wearable device according to anyone of the preceding claims 1 to 9, wherein the said processing unit (5) is composed of a flexible electronic card.
Method of measuring the power of an impact of the wearable device according to claim 1 comprising a plurality of impact sensors (2) and at least one inertial sensor,
characterized in that
it comprises the following steps:
a) acquiring signals of acceleration from the inertial sensor;

b) obtaining the velocity vector along a predetermined direction by integrating the acceleration signals;

c) obtaining the force vector of the impact from the impact sensors, said sensors being positioned in such a way that the force vector is along the said predetermined direction of the velocity vector;

d) calculate the power of the impact as the dot product of the force vector and the velocity vector and
wherein the velocity vector is taken into account for the calculation of the power of the impact only in the time period when said velocity is decreasing during the impact.
Method according to claim 11, wherein a low-pass filter is applied to the acceleration signal before step b).
Method according to claim 11 or 12, wherein a high-pass filter is applied to the acceleration signal before step b).