FR3058538A1 - MULTIPARAMETRIC METHOD FOR QUANTIFYING BALANCE - Google Patents

Abstract

The invention relates to a method for quantifying the equilibrium of an individual to obtain a value representative of the equilibrium of said individual, said method being implemented by a device comprising at least one data processing module connected to a device. storage means and said method comprising: a) a step of recording, on the storage means, at least one statokinesigram of the individual obtained from a platform comprising pressure and / or force sensors, b) a step of extraction, by the data processing module and from the statokinesigramme (s) of the individual recorded on the storage means, values of at least one relative trajectory parameter the position of the center of pressure and the values of at least one trajectory parameter relative to the stability of the center of pressure, c) a step of determination, by the data processing module, of the value of more their quantifiers, from the values of the trajectory parameters extracted in step b), d) a step of comparing, by the data processing module, said values of several quantizers with the values of the same quantizers obtained from statokinesigrams of reference, and e) a step of determining, by the data processing module, said value representative of the equilibrium of the individual at the end of the comparison.

Description

Holder (s): National center for scientific research, FRENCH state - MINISTRY OF DEFENSE - CENTRAL DIRECTORATE OF ARMY HEALTH SERVICE, HIGHER NORMAL SCHOOL OF ACHAN, UNIVERSITE PARIS DESCARTES.

Agent (s): API CONSEIL.

MULTIPARAMETRIC PROCESS FOR QUANTIFYING BALANCE.

FR 3 058 538 - A1 f5 // The invention relates to a method for quantifying the balance of an individual to obtain a value representative of the balance of said individual, said method being implemented by a device comprising at least a data processing module connected to a storage means and said method comprising:

a) a step of recording, on the storage means, at least one statokinesigram of the individual obtained from a platform comprising pressure and / or force sensors,

b) a step of extraction, by the data processing module and from the statokinesigram (s) of the individual recorded on the storage means, of the values of at least one relative trajectory parameter the position of the center of pressure and the values of at least one trajectory parameter relating to the stability of the center of pressure,

c) a step of determining, by the data processing module, the value of several quantifiers, from the values of the trajectory parameters extracted in step b),

d) a step of comparison, by the data processing module, of said values of several quantifiers with the values of the same quantifiers obtained from reference statokinesigrams, and

e) a step of determination, by the data processing module, of said value representative of the balance of the individual at the end of the comparison.

The present invention relates to the field of quantifying the equilibrium of an individual. The present invention relates more particularly to a multi-parameter method for quantifying the balance of a person, a device capable of implementing this method and a system integrating said device. The present invention allows in particular a monitoring of the evolution of this balance, for example in the context of a rehabilitation process, in a process of self-quantification or in the elderly person, in particular so as to alert to risks of fall, in a home maintenance approach.

[Prior art] [002] Self-measurement (“quantified self”) is an increasingly common practice and it includes more and more parameters. Likewise, the devices on the market allowing the quantification of different functions relating to self-measurement such as sleep or walking are increasing.

Static and dynamic balances are essential components of our daily movements and a lack of balance is a major cause of fall. In addition, the balance can be modified (i.e. reduced) following life accidents such as accidents targeting the lower limbs but also in connection with the manifestation of mental disorders or strokes such as strokes. This postural instability linked to a disturbance in motor, sensory and / or cognitive functions can favor a fall which can be fatal or lead to serious decompensations.

According to estimates from the World Health Organization in 2012, nearly 424,000 people worldwide lose their lives each year as a result of falls, placing falls second among the causes of accidental death in the world. According to the Institut de Veille Sanitaire, every year in France there are 450,000 falls in people over the age of 65 and it is the most common cause of death in the elderly with 4,000 to 4,500 cases per year. France.

The fall of people is therefore a major public health problem because of its frequency and its medical and social consequences; especially and especially in the elderly. For example, post-fall syndrome results in a phobia of falling with a loss of self-confidence to perform acts of life

Ref: 0504-064a daily and eventually leads to a grabatisation. Thus, many treatments aim to restore the balance of individuals and exercises are aimed at maintaining it.

Despite these challenges, there is today no intuitive, reliable and inexpensive process or device for quantifying an individual's balance.

Doctors nowadays appreciate balance through methods of visual monitoring of the patient, most often via standardized tests such as the Romberg test. The latter can help the doctor make a diagnosis and identify the possible causes of static ataxia. However, such monitoring allows to qualify and not to quantify objectively the balance of an individual. However, quantitative methods could make it possible to reinforce the objectivity, the homogeneity of the interpretations, give the possibility of making comparisons of such tests (eg follow-up over time or within a group of individuals) and to identify imperceptible behavior via methods of visual monitoring of the patient.

There are today methods of evaluating the balance generally based on the study of the displacement of the center of pressure measured from a force platform. An effort of standardization was notably carried out in the years 80-90 with the establishment of "standards 85", including the definition of a protocol including the placement of individuals in a cabin with standardized dimensions, imposing a position of the feet in order to ensure reproducibility of the parameters with an acquisition time of 51.2 seconds at a sampling frequency of 5 Hz (Gagey et al 1988 - Statistical studies of measurements made on normal humans using the standardized clinical stabilometry platform).

In this context, the parameters usually determined from the pressure center displacement data, generally at a frequency of 10 Hz minimum, make it possible to account for the subject's ability to maintain their orthostatic equilibrium and can be selected from :

- the length of the movement,

- the area of the plot of the statokinesigram corresponding to the area on which the center of pressure moves and is measured in mm ² via the calculation of the area of the confidence ellipse (based on a Gauss curve) which contains 90% pressure center support points,

- the length as a function of the surface (LFS) which corresponds to the ratio between the distance traveled by the center of pressure and the surface of the confidence ellipse,

- the variance of the speed along the Y axis (VFY), or

- the oscillation frequencies.

Ref: 0504-064a [0010] If posturography is the most suitable means in the assessment of standing, its place in the assessment of balance disorders remains disputed. Several reasons hinder its use: cost of acquisition, completion, reproducibility of exams, their sensitivity, their specificity, the difficulties of interpreting the results (large number of measurements to compare between two states). Indeed, these methods are interested in the parameters of the displacement of the center of pressure independently and do not combine them. They do not make it possible to obtain, in the absence of a professional and by a simple and rapid method, a value representative of the balance of the individual.

The force platform designated Wii fit balance board (registered trademark) makes it possible to follow the displacement of the center of pressure and also offers a function for measuring the "Wii fit age" in particular based on a measurement of the displacement of the center pressure. Many articles have been interested in the evaluation of equilibrium via this force platform and although it makes it possible to obtain data of displacement of the center of pressure similar to those obtained with force platforms based on sensors with Wheastone bridges (Clark et al, 2010 - Validity and reliability of niintendo wii balance board for assessment of standing balance), the measurement of balance by this type of device is not very conclusive (Gobie et al 2014 - Using the Wii Fit as a tool for balance assessment and neurorehabilitation: the first hait decade of “Wii-search”).

This lack of performance or at best this reduced performance is probably linked to the mono factorial appreciation of the displacement of the pressure center and to random modifications of the acquisition frequency over time which may lead to over-acquisition or a sub-acquisition. The rare times when multi-parameter methods are used, the latter are not able to produce satisfactory results because the data to be studied are very complex and difficult to model. Thus, the analytical methods previously used to assess the balance do not provide a single, reliable value, easily measurable using a simple and inexpensive device.

There is therefore a need for a device for quantifying the balance which can be performed routinely by anyone concerned with monitoring their balance and this at low cost, but also by the public authorities or the health personnel.

Ref: 0504-064a

Technical problem The aim of the invention is to remedy the drawbacks of the prior art. In particular, the object of the invention is to propose a method for quantifying the reliable equilibrium, that is to say making it possible to establish a value representative of the state of equilibrium of the individual, rapid, simple, and not necessarily requiring the intervention of a specialist in the field of posturology. Note that this process is not intended to replace the general practitioner or specialist and does not pose a diagnosis.

The invention further aims to propose a device for quantifying the balance which can be integrated into a complete system for quantifying the balance.

[Short description of the invention] To this end, the invention relates to a method for quantifying the balance of an individual to obtain a value representative of the balance of said individual, said method being implemented by a device comprising at least one data processing module connected to a storage means and said method comprising:

a) a step of recording, on the storage means, at least one statokinesigram of the individual obtained from a platform comprising pressure and / or force sensors,

b) a step of extraction, by the data processing module and from the statokinesigram (s) of the individual recorded on the storage means, of the values of at least one relative trajectory parameter the position of the center of pressure and the values of at least one trajectory parameter relating to the stability of the center of pressure,

c) a step of determining, by the data processing module, the value of several quantifiers, from the values of the trajectory parameters extracted in step b),

d) a step of comparison, by the data processing module, of said values of several quantifiers with the values of the same quantifiers obtained from reference statokinesigrams, and

e) a step of determination by the data processing module of said value representative of the balance of the individual at the end of the comparison.

Ref: 0504-064a The implementation of this method includes the determination of several quantifiers being then treated jointly in a step of comparison and determination of a value representative of the equilibrium. Unlike the prior art, the method according to the invention includes taking into account and combining trajectory parameters related to the position and stability of the center of pressure so as to obtain a value representative of the equilibrium.

According to other optional characteristics of the process:

- step b) further comprises extracting the values of at least one trajectory parameter relating to the dynamics of the center of pressure. Taking into account the values of a trajectory parameter linked to the dynamics of the pressure center makes it possible to improve the relevance of the representative value obtained as can be shown by the curves of ROC (Receiver Operating Characteristic) curves and more particularly the area data under the curve (AUC).

- at least one of the quantifiers determined in step c) is selected from: the average value, the median value, the variance value, and an extreme value, of said trajectory parameter. Alternatively, at least one of the quantifiers determined in step c) is selected from: the mean value, the median value, the variance value, the mean value of the squares and an extreme value, of said trajectory parameter.

- step b) is carried out using two statokinesigrams generated during a Romberg test. The Romberg test is a test used by many posturology professionals for decades and it makes it possible to obtain a value representative of the balance in the context of the invention, in particular by comparing the values of the statokinesigrams obtained. eyes closed or eyes open.

at least one of the quantifiers determined in step c) is an extreme value of said trajectory parameter, said extreme value corresponding to a percentile between a percentile greater than or equal to 5 and a percentile less than or equal to 15, or else to a percentile between a percentile greater than or equal to 85 and between a percentile less than or equal to 95, values of the trajectory parameter. The analysis of extreme values, which is generally not

Ref: 0504-064a not found in current methods of balance analysis, allows to generate particularly relevant results in the context of the invention.

- steps d) and e) are carried out by implementing the values of the quantifiers determined in step c) in a notation algorithm previously calibrated on the basis of the values of the same quantifiers obtained from the reference statokinesigrams. The use of a notation algorithm integrating steps d) and e) notably makes it possible to shorten the duration of implementation of the method.

- the previously calibrated notation algorithm was obtained by implementing a statistical method of supervised learning, preferably a RANKING FOREST or RANDOM FOREST method. The inventors have discovered that in the context of the quantification of the balanced, the RANKING FOREST or RANDOM FOREST methods are very effective. Preferably, the statistical method of supervised learning is used in combination with a Bagging step. Thus, the previously calibrated scoring algorithm can be obtained by the implementation of a statistical method of supervised learning including the implementation of a Bagging step.

- The method comprises in step c) determining the value of at least five quantifiers. The methods of the prior art are generally based on the one-to-one comparison of values extracted from the statokinesigrams whereas, in the context of the method according to the invention, the combination of at least five quantifiers allows better performance.

The invention further relates to a device for quantifying the balance of an individual, said device comprising:

- a communication module capable of receiving a statokinesigram of said individual,

a storage means capable of recording the statokinesigram, and

at least one data processing module able to connect to the storage means, said data processing module being configured to:

Ref: 0504-064a o Extract, from a statokinesigram of said individual transmitted by the communication module, values of at least one trajectory parameter relating to the position of the pressure center and values of at least one parameter of trajectory linked to the stability of the center of pressure, o Determine several quantifiers, from the values of the extracted trajectory parameters, o Compare the values of said quantifiers with the values of the same quantifiers obtained from reference statokinesigrams, and o Determine a value representative of the individual's balance based on said comparison.

The invention further relates to a system for quantifying the balance of an individual, comprising:

a platform, said platform being adapted to receive an individual and comprising pressure and / or force sensors configured to generate raw data, at a first frequency, as a function of a pressure exerted by the feet of the individual on the platform,

- a raw data processing unit, arranged to obtain at least one statokinesigram of the individual from the raw data generated by the platform, and

- a device for quantifying the balance according to the invention, capable of communicating with the processing unit.

Other advantages and characteristics of the invention will appear on reading the following description given by way of illustrative and nonlimiting example, with reference to the appended figures which represent:

• Figure 1 shows a diagram of the method for quantifying the balance according to the invention.

• Figure 2 shows a statokinesigram according to the invention where the axis y corresponds to the anteroposterior axis and the x axis to the medio-lateral axis.

• Figure 3A and 3B represent a statokinesigram according to the invention, Fig 3A corresponding to the projection on the X axis of all the values of the parameter "position of the center of pressure along the X axis" and Fig 3B representing projection

Ref: 0504-064a on the Y axis of all the values of the parameter "position of the center of pressure along the Y axis"

• Figure 4, represents the set of values as a function of time (X axis) of the “time balance” parameter calculated on the basis of the statokinesigram presented in Figure 2. The dotted line representing a threshold value for the calculation of the parameter ballistic interval according to the invention.

• Figure 5, represents the projection on the X axis of all the values of the parameter "position of the center of pressure along the X axis" as well as four quantifiers calculated from this parameter.

• Figure 6 shows an example of implementation of the method for quantifying the balance according to the invention. The numbers arranged in oval shapes correspond to process steps while those arranged in the rectangles correspond to values obtained after the implementation of these steps.

• Figure 7 represents a decision tree built from a Ranking Forest type algorithm. F1 corresponds to the closed eyes / open eyes ratio for the 90th percentile of the ballistic interval, F2 is the closed eyes / open eyes ratio for the variance of the position on the Y axis and F3 is the variance of the temporal equilibrium eyes closed.

• Figure 8 shows a device for quantifying the balance according to the invention.

• Figure 9 shows a system for quantifying the balance according to the invention.

[Description of the invention!

In the following description, the "balance" within the meaning of the invention corresponds to the postural balance related to the stability of the body and more particularly to the stability of the center of gravity of an individual. The concept of balance according to the invention is linked to the ability of an individual to avoid falling and includes static balance and dynamic balance.

The “quantification of equilibrium” corresponds, within the meaning of the invention, to the assignment of a value for example a score, a classification or a note to a trajectory or a displacement of the center of pressure d 'an individual. This quantification of

Ref: 0504-064a the balance allows to obtain a value representative of the balance and can be performed on the basis of many scales of different sizes (e.g. 1.5, 10, 100) linear or not. The representative value of the balance assigned during the quantification of the balance can also allow an individual to be assigned to a group, for example via a decision rule. The quantification according to the invention can be carried out in particular by the implementation of a notation algorithm generated from a learning method.

By "model" or "rule" or "notation algorithm" is meant within the meaning of the invention a finite series of operations or instructions for quantifying the equilibrium, that is to say classify one or more individuals within previously defined groups Y, or to prioritize one or more individuals within a classification. The implementation of this finite sequence of operations makes it possible for example to assign a label Y _o to an observation described by a set of characteristics X _o thanks for example to the implementation of a function f capable of reproducing Y having observed X.

Y = f (X) + e where e symbolizes noise or measurement error By “supervised learning method”, we mean within the meaning of the invention a method making it possible to define a function f from a base of n labeled observations (Xi ... _n , Yi ... _n ) where Y = f (X) + e.

Within the meaning of the invention, the term "center of pressure" means the projection onto the horizontal plane passing through the point of contact between the subject and the ground of the barycenter of the vertical forces exerted on the ground by the body of the subject (Benda, BJet al 1994. Biomechanical relationship between center of gravity and center of pressure during standing. Rehabilitation Engineering, IEEE Transactions on 1994, 2, 3-10). These measurements can be carried out using a platform analyzing the distribution of pressures under the sole such as a force platform or a shoe or deformable soil. Without being an exact projection of the center of gravity, the center of pressure is strongly linked to the center of gravity. The displacement of the center of pressure is generally faster and wider than that of the center of gravity in order to keep it in balance. It reflects the efforts made by an individual to control the position of his center of gravity.

For the purposes of the invention, the term "center of gravity" means the body center of gravity of an individual. It corresponds to the meaning of the invention at the barycenter of the masses of the individual. The center of gravity cannot be maintained in perfect stability and by

Ref: 0504-064a example when standing the center of gravity swings back and forth and left to right.

The term "statokinesigram" or "trajectory of the center of pressure" means data relating to the trajectory or displacement of the center of pressure. The statokinesigram can also be called a stabilogram and is generally generated by means of a platform such as a force platform, "intelligent" ground equipped with sensors or soles equipped with pressure sensors. It corresponds to the calculated trajectory of the center of pressure over time. The trajectory of the center of pressure is defined by a set of position data in an orthonormal reference frame x, y as a function of time and during a defined duration.

The “platform” within the meaning of the invention corresponds to a device resting on the ground comprising sensors, for example of the force or pressure sensors type, producing an electrical, optical or magnetic signal proportional to the force applied on said platform by the feet of an individual. The sensors used can for example be strain gauges mounted in a Wheastone bridge in order to generate the 3 components of force and moment Fx, Fy, Fz, Mx, My and Mz; piezoelectric pressure sensors, piezoresistive pressure sensors or capacitive pressure sensors. Within the meaning of the invention, the platform is configured to generate "raw data" from said sensors.

By "parameter" and more particularly by "parameter calculated from the trajectory of the center of pressure" is meant in the sense of the invention a transformation of the trajectory of the center of pressure into a set of values.

By “quantifier” and more particularly by “quantifier calculated from transformation of a parameter obtained”, is meant within the meaning of the invention a single value obtained by selection or transformation of the set of values of a setting.

By "reference quantifier" means a value obtained from a reference statokinesigram from a person whose balance has been previously qualified.

Within the meaning of the invention, the "ROC curve (Receiver Operating Characteristic)" represents the change in sensitivity (rate of true positives) as a function of the specificity (rate of false positives) of a model for each given threshold value. It’s a curve

Ref: 0504-064a increasing between point (0,0) and point (1,1) and in principle located above the first bisector. Indeed, a random prediction would give a line corresponding to the first bisector. For an ROC curve, the more the curve is above the first bisector, the better the prediction and the area under the ROC curve (AUC - Area Under the Curve) gives an indicator of the quality of the model (1 for a ideal prediction, 0.5 for a random prediction).

In the following description, the same references are used to designate the same elements.

According to a first aspect, the invention relates to a method of quantification 1 of the balance of an individual to obtain a value representative of the balance of said individual. While, until now, the recognized methods are based on assessments or visual observations and are not completely objective, the method according to the present invention has the advantage of generating a value also designated by a score, and more particularly an encrypted value. In addition, this value can be generated completely automatically, objectively and without it being necessary to supply the process with information on the individual in addition to one or more statokinesigram (s).

This quantification method 1, shown in Figure 1, is implemented by a device at least one data processing module 220 connected to a storage means 280. Advantageously, the device can be the quantization device 2 according to the invention.

More particularly, as presented in FIG. 1, the quantification method 1 according to the invention comprises:

a) a recording step 10, on the storage means 280, of at least one statokinesigram of the individual 110 obtained from a platform 310 comprising pressure and / or force sensors 312,

b) an extraction step 20, by the data processing module 220 and from the statokinesigram of the individual 110 recorded on the storage means 280, values of at least one trajectory parameter relating to the position 121

Ref: 0504-064a of the pressure center and values of at least one trajectory parameter relating to the stability 122 of the pressure center,

c) a step 30 of determining, by the data processing module 220, the value of several quantifiers 130, from the values of the trajectory parameters 121, 122 extracted in step b),

d) a step of comparison 40, by the data processing module 220, of said values of several quantifiers 130 with the values of the same quantifiers obtained from reference statokinesigrams 111, and

e) a step 50 of determining, by the data processing module 220, said representative value 160 of the balance of the individual at the end of the comparison 40.

The quantification method 1 of the balance according to the invention is based on the processing of trajectory data of the center of pressure of an individual as transcribed in a statokinesigram 110.

This trajectory data of the center of pressure of an individual generally corresponds to the trajectory data of the center of pressure and is generally acquired when the individual is standing.

Preferably, the acquisition is done standing, for example with feet together or at the hips.

The influence of visual afferents on stability is measured by generating two kinetics of displacement or trajectory of the center of pressure, a first with open eyes and a second with closed eyes. Thus, preferably, the extraction step 20 is carried out from a statokinesigram 110 obtained while the individual with open eyes and a statokinesigram 110 obtained while the individual with closed eyes.

In particular, the duration of acquisition of a statokinesigram 110 can be between 5 and 70 seconds, preferably between 20 and 60 seconds and even more preferably between 20 and 40 seconds.

Advantageously, the trajectory data of the center of pressure can be obtained during a Romberg test. Romberg’s test involves placing the individual standing, motionless, arms alongside, looking straight ahead. The displacement of the pressure center is recorded for 30 seconds. For example, a 30 second recording is made with eyes open and another 30 second recording is made with eyes closed.

Ref: 0504-064a [0024] Alternatively, it is possible to increase the sensitivity of the process by using a foam placed on a support and capable of deforming or disturbing proprioceptive and tactile information. This foam may for example have a thickness of 1 to 10 millimeters and a density of between 100 and 500 kg / m ³ .

The method according to the invention can be implemented from data relating to the displacement of the pressure center, that is to say on the basis of at least one statokinesigram 110 or else on the basis of the data raw from the sensors and relating to the displacement of the pressure center.

The quantification method 1 according to the invention comprises a step of recording 10 of at least one statokinesigram 110 of the individual, on a storage means 280. This recording can be carried out on all types of memory such as transient or non-transient memories. This recording is preferably carried out on a non-transient memory.

The statokinesigram 110 can be generated well before the implementation of the method according to the invention and at a remote location. Alternatively, the statokinesigram 110 can be generated just before the implementation of the quantification method 1 of the balance according to the invention and by the same system. Thus, the quantification method 1 according to the invention can previously include a step of generating the raw data relating to the displacement of the pressure center 11. This step is nevertheless optional and it can be carried out upstream of the quantification method 1 according to the invention. invention by known devices and methods. The raw data relating to the displacement of the pressure center correspond for example to the pressure values measured by each of the sensors present on the platform.

This raw data can be the subject of a transformation step 12 into trajectory data of the center of pressure (i.e. a statokinesigram). This transformation step is also optional because it can be carried out upstream of the process according to the invention by known methods. FIG. 2 is a graphic representation of a statokinesigram 110 according to the invention and more particularly of the plot 125 of the statokinesigram 110.

The quantification method 1 according to the invention comprises a step of extracting 20 the values of several trajectory parameters 120 from a statokinesigram 110 of the individual. This extraction step can be carried out by a

Ref: 0504-064a data processing module 220 from the statokinesigram of the individual 110 recorded on a storage means 280.

This extraction step 20 allows the transformation of the pressure center trajectory data (i.e. a statokinesigram), so as to obtain parameters retranscribing the properties of this displacement of the pressure center. The parameters thus calculated are for example, for each of the instants t, the speed, the acceleration, the position on an axis of the center of pressure.

This extraction step 20 can be carried out from a set of data relating to the displacements of the pressure center such as for example the trajectory data of the pressure center or the raw data of the force platform. In fact, alternatively, the extraction of the parameters according to the invention can be carried out directly from the raw data of the sensors in a single step including the generation of trajectory data 12 of the pressure center then the transformation into parameters120.

In the context of the implementation of the method according to the invention, the inventors have classified these transformations carried out during the extraction step 20 into three categories: i) those associated with the position of the pressure center, ii) those associated with the stability of the center of pressure, and iii) those associated with the dynamics of the displacement of the center of pressure. The inventors have discovered that in order to obtain a reliable quantification of an individual's equilibrium, a multi-parameter method combining the analysis of several parameters from different families of parameters is essential.

Among a multitude of trajectory parameters, the inventors have selected the most effective trajectory parameters for quantifying the balance. They discovered that the method must integrate the calculation of at least one trajectory parameter linked to the position 121 of the pressure center and at least one trajectory parameter linked to the stability 122 of the pressure center.

Thus, the trajectory parameters calculated within the framework of the quantification method 1 according to the invention include:

at least one parameter relating to the position 121 of the pressure center, and

- At least one parameter relating to the stability 122 of the pressure center.

In fact, the inventors have determined that the use of at least one parameter of these two classes makes it possible to increase the precision of the quantification and thus to obtain

Ref: 0504-064a significantly superior performance, both compared to the literature but also compared to the rating algorithms according to the invention using the descriptors from the literature.

In addition, the inventors have also shown that the addition of a parameter relating to the dynamics 123 of the pressure center, to the stability and position parameters of the pressure center, could make it possible to improve the quantification. Thus, according to the invention, advantageously, the calculated trajectory parameters can also include at least one parameter linked to the dynamics 123 of the pressure center.

Transformations associated with the position 121 of the center of pressure, The position of the center of pressure along the X axis [0039] This position corresponds to the position of the center of pressure with respect to the midline of the orthonormal coordinate system in a plane of the X axis. For example, in the case of a position shifted from the center of pressure to the left at an instant t, the position along the X axis presents, for this instant t a negative value sign of a hyper left support. This position can for example be measured in millimeters.

FIG. 3A represents a set of values of the parameter "position of the center of pressure along the X axis" 121a obtained from the statokinesigram 110 presented in FIG. 2.

The position of the center of pressure along the Y axis. This position corresponds to the position of the center of pressure with respect to the midline of the orthonormal reference frame in a plane of the Y axis. For example, in the case position shifted backwards at an instant t, the position along the Y axis presents, for this instant t a negative value sign of a posterior hyper support. This position can for example be measured in millimeters.

FIG. 3B represents all the values of the parameter "position of the center of pressure along the Y axis >> 121b obtained from the statokinesigram 110 presented in FIG. 2.

The radius in polar coordinates [0045] This distance corresponds to the distance from the center of pressure relative to the average position of the center of pressure according to the orthonormal plane (0,0). For example, in the event of a 4-millimeter offset of the center of pressure from the mean position of the center of pressure along an axis of 60 °, at an instant t, the radius in polar coordinates has, for this instant t, a value of 4 millimeters.

Ref: 0504-064a [0046] Such a transformation makes it possible to quantify the overall distance of the center of pressure from a point of origin without being limited to the X and Y coordinates of the center of gravity.

Transformations associated with the stability 122 of the pressure center [0048] Radial equilibrium The radial equilibrium corresponds to the maximum distance of the pressure center from its current value at a given instant over a predefined duration of t seconds .

The duration taken into account for the calculation of the radial balance may be between 0.05 to 10 seconds, preferably from 0.1 to 2 seconds.

The radial balance is calculated for all the sampling points of the displacement of the center of pressure over the duration of the acquisition. It is thus a function of time and can be measured for example in millimeters.

Temporal equilibrium Temporal equilibrium corresponds to the time necessary for the center of pressure to move more than r millimeters from its current position at a given time. The distance r taken into account for the calculation of the temporal equilibrium can be between 0.1 to 20 millimeters, preferably from 1 to 10 millimeters.

The time equilibrium is calculated for all the sampling points of the displacement of the pressure center over the duration of the acquisition. It is thus a function of time and can be measured for example in seconds.

Ballistic interval [0057] The ballistic interval corresponds to the time interval between two positions of equilibrium. An equilibrium position corresponds to a strong value of temporal equilibrium. Preferably, an equilibrium position corresponds to a moment when the temporal equilibrium is greater than 60%, preferably greater than 80%, of the maximum observed on the statokinesigram.

The ballistic interval is calculated over the duration of the acquisition and the number of values obtained can vary depending on the acquisitions. It is not a function of time and can be measured, for example, in seconds. FIG. 4 represents as a function of time all the values of the “temporal balance” parameter calculated on the basis of the statokinesigram 110 presented in FIG. 2. The values of the “ballistic interval >>” parameter 122a are for example expressed in seconds and correspond at the times between the values between P1 and P3, and P4 and P6. For example, this setting

Ref: 0504-064a includes the values corresponding to the time differences between: P3 - P2; P3 - P1; P6 - P1; P6 - P2; P6 - P3; P6 - P5; P5 - P1; P4 - P3.

Transformations associated with the dynamics 123 of the center of pressure [0060] Speed of the displacement of the center of pressure [0061] The speed of the displacement of the center of pressure is calculated for all the sampling points of the displacement of the center of pressure on the duration of the acquisition. It is thus a function of time and can be measured for example in millimeters per second.

Acceleration of the displacement of the pressure center [0062] The acceleration of the displacement of the pressure center is calculated for all the sampling points of the displacement of the pressure center over the duration of the acquisition. It is thus a function of time and can be measured for example in millimeters per second squared.

Power The power according to the invention corresponds to the value of the dot product of speed and acceleration. This parameter represents the energy expended by the individual to modify the norm of the speed of the center of pressure.

Deviation [0067] The deviation according to the invention corresponds to the vector product standard of speed and acceleration. It represents the energy expended by the individual to modify the direction of the velocity of the center of pressure (i.e. its displacement, its trajectory or its movement).

In the context of the study of a statokinesigram 110, the power and the deviation are two parameters which can advantageously replace the length of the displacement of the pressure center, the variance of the speed as a function of the Y axis (VFY ) or also the LFS (ie ratio of the length on the surface), providing information according to the prior art on the energy consumption expended by the subject to control his posture. In particular, the deviation proposed by the inventors makes it possible to assess the individual's energy expenditure from a new angle and is more relevant in the method according to the invention than the parameters proposed in the prior art (eg VFY, LFS ).

Ref: 0504-064a The quantification method 1 according to the invention can also include a step 30 of determining several quantizers 130 from the trajectory parameters 120. This step of determining 30 can be carried out by a processing module 220. Once the trajectory parameters 120 have been generated during the step of extracting the trajectory data from the pressure center, the works of the prior art have generally focused exclusively on the mean and the variance of these parameters during an acquisition period.

In the method developed by the inventors, the latter are interested in many other methods of transforming these parameters in order to generate, from these sets of values and in combination with other sets of values, a single value representative of an individual's balance. Thus, new quantifiers never used in the past have been generated.

The determination step 30 of several quantizers 130 from the trajectory parameters 120 therefore consists in transforming, for each trajectory parameter 120, the set of values into a single value which can be used in the context of a comparison for example through a statistical comparison model. This transformation into a single value (quantifiers) can be repeated for several trajectory parameters or for the same trajectory parameter. FIG. 5 represents some of these quantifiers as calculated for the parameter "position of the center of pressure along the X axis".

The most informative quantifiers in the context of the quantification method according to the invention are the mean value, the median value, the variance, of the mean of the squares, or an extreme value, of a trajectory parameter 120 extract. Thus, preferably, the quantification method 1 according to the invention comprises, for at least one parameter, the calculation of the mean value 127, of the median value 128, of the variance, of the mean of the squares or of at least minus an extreme value, of said trajectory parameter (121,122,123). Even more preferably, the quantification method 1 according to the invention comprises, for at least one parameter, the calculation of at least one extreme value of said parameter.

The extreme values of a parameter are obtained by determining a percentile. A percentile, or percentile, can for example be calculated by ordering and then sorting all of the values of a parameter into 100 subsets comprising the same number of values. FIG. 5 represents the percentilel 126 and the percentile 95 129 of the parameter “position of the center of pressure along the X axis” corresponding respectively to the highest value of the position of the center of pressure along the X axis within the 10

Ref: 0504-064a% of the lowest values and the lowest value of the position of the center of pressure along the X axis within the 5% of highest values. Thus, percentile 10 is the value separating 10% of the lowest values and 90% of the highest values while percentile 95 is the value separating 95% of the lowest values and 5% of the highest values Preferably , an extreme value of a trajectory parameter 120 corresponds to a percentile less than or equal to 15 or else to a percentile greater than or equal to 85; more preferably, at a percentile less than or equal to 10 or else at a percentile greater than or equal to 90 and even more preferably at a percentile less than or equal to 5 or else at a percentile greater than or equal to 95.

Alternatively, an extreme value of a trajectory parameter 120 may correspond to a percentile greater than or equal to percentile 5 and less than or equal to percentile 15 (low extreme values) or to a percentile greater than or equal to percentile 85 and a percentile less than or equal to percentile 95 (high extreme values).

In addition, beyond the calculation of a quantifier 130, the inventors have shown that the comparison of open eyes (O) / closed eyes (F) on certain parameters or quantifiers would make it possible to differentiate performance in terms of equilibrium . Thus, in particular, the quantification method 1 according to the invention comprises for at least one quantifier, the calculation of an O / F or F / O ratio.

During their development, the inventors have selected a set of quantifiers 130 which are particularly relevant for quantifying the equilibrium. Preferably, within the framework of the quantification method 1 according to the invention, the quantizer linked to the position of the pressure center is selected from the following values:

- the average or median value on the X or Y axis of the pressure center,

- the average value of the squares of the X or Y axis values of the center of pressure,

- the extreme values on the X or Y axis of the pressure center, and

- the variance on the X or Y axis of the pressure center.

In particular, within the framework of the quantification method 1 according to the invention, the quantizer linked to the extreme values on the X or Y axis of the pressure center is selected from:

the low extreme values of the position of the center of pressure along the transverse axis (Y), preferably included in the percentiles less than or equal to 10, these values correspond to the maximum of retropropulsion observed, and

Ref: 0504-064a

- the extreme high values of the trajectory of the center of pressure along the transverse axis (Y), preferably included in the percentiles greater than or equal to 90.

Preferably, the quantification method according to the invention comprises the calculation of at least one, more preferably at least two, quantifiers linked to the position of the pressure center which can be independently selected from the following quantifiers:

- percentile 15, preferably percentile 10 and even more preferably percentile 5 of the position of the center of pressure on the X axis, preferably for a displacement of the center of pressure measured while the individual had the eyes closed,

- the median value on the Y axis of the center of pressure, preferably for a displacement of the center of pressure measured when the individual had his eyes closed,

- the median value on the X axis of the center of pressure, preferably for a displacement of the center of pressure measured when the individual had his eyes open,

- percentile 15, preferably percentile 10 and even more preferably percentile 5 of the position of the center of pressure on the Y axis, preferably for a displacement of the center of pressure measured while the individual had the eyes closed,

- the variance on the Y axis of the trajectory of the center of pressure, preferably for a displacement of the center of pressure measured when the individual had his eyes closed,

- the variance on the X axis of the trajectory of the center of pressure, preferably for a displacement of the center of pressure measured when the individual had his eyes closed,

- the values of mean or median on the Y axis and more particularly of the ratio between these values for a statokinesigram recorded while the individual had the eyes open and these values for a statokinesigram recorded while the individual had the eyes closed ,

- the extreme values of the radius in polar coordinates such as for example:

o percentile 15, preferably percentile 10 and even more preferably percentile 5 of the radius in polar coordinates of the center of pressure, preferably for a displacement of the center of pressure measured when the individual had his eyes closed,

Ref: 0504-064a o percentile 85, preferably percentile 90 and even more preferably percentile 95 of the radius in polar coordinates of the center of pressure, preferably for a displacement of the center of pressure measured when the individual had Open eyes,

- the median of the radius in polar coordinates of the center of pressure, and

- the mean value of the squares of the radius in polar coordinates of the center of pressure.

Preferably, the quantification method 1 according to the invention comprises the calculation of at least one, more preferably at least two, quantifiers related to the stability of the pressure center which can be independently selected from the following quantifiers :

- the 10th percentile of the radial equilibrium for a period of 0.5 seconds, preferably for a displacement of the center of pressure measured when the individual had his eyes closed,

- the 90th percentile of the radial equilibrium for a duration of 0.1 seconds, preferably for a displacement of the center of pressure measured when the individual had his eyes open,

- the variance of the temporal equilibrium for a distance between 1 to 10 millimeters, preferably from 1 to 5 millimeters, preferably the ratio of the value obtained for a displacement of the center of pressure measured while the individual had the eyes open to the value obtained for a displacement of the center of pressure measured when the individual had his eyes closed,

- the mean value, of the mean value of the squares or the median value, preferably the mean value of the ballistic interval values, preferably for a displacement of the center of pressure measured while the individual had his eyes closed, and

- the extreme high values of the ballistic interval such as for example the 85th percentile, preferably the 90th percentile and even more preferably the 95th percentile of the ballistic interval.

Preferably, within the framework of the quantification method according to the invention the quantizer linked to the dynamics of the center of pressure is selected from the mean, the median, the mean of the squares or the variance of the power, preferably for displacement of the center of pressure measured while the individual's eyes were open.

Ref: 0504-064a Preferably, the quantification method according to the invention comprises the calculation of at least one, more preferably at least two, quantifiers linked to the dynamics of the pressure center which can be independently selected among the following quantifiers:

- the extreme low values of the acceleration of the displacement of the center of pressure such as for example the percentile 15, preferably the percentile 10,

- the extreme low values of the deviation of the displacement of the center of pressure such as for example the percentile 15, preferably the percentile 10, even more preferably the percentile 5, preferably for a displacement of the center of pressure measured while the individual's eyes were open, and

- the extreme high values of the speed of displacement of the center of pressure such as for example the percentile 85, preferably the percentile 90, preferably for a displacement of the center of pressure measured while the individual had his eyes open.

The inventors propose for the first time a multi-parameter method based on the combination of a plurality of parameters and / or quantifiers. Thus, in addition to extracting at least one parameter linked to the stability 122 of the pressure center and at least one parameter linked to the position 121 of the pressure center, they determined that in order to obtain a more reliable value in the method of quantization 1 according to the invention, it is preferable to calculate and then combine several quantifiers, for example several quantifiers relating to the same trajectory parameter. Thus, in order to best quantify the equilibrium and more particularly to allow the prediction of a risk of falling, it is preferable to calculate, from the trajectory parameters 120, at least five quantifiers 130, even more preferably at least eight quantifiers 130.

In addition, the quantification method 1 according to the invention comprises a step 40 of comparing several values of quantifiers 130 with the values of the same quantifiers obtained from reference statokinesigrams 111.

This comparison step can be implemented by means of a data processing module 220 and it can be carried out using known statistical methods. Preferably, this comparison step 40 can be carried out on the basis of comparison, classification or learning models such as: perceptron, Kernel, Multiple kernel learning, Support vector machine, decision trees, drills

Ref: 0504-064a random, Bagging, AdaBoost, k-nearest neighbor and / or penalized linear fisher discriminant.

Among the statistical methods, the linear regression models are simple and easy to implement. However, these linear models are limited because of the linearity assumption and they are not optimal for the quantification method 1 according to the invention. Thus, the comparison step 40 includes the use of a non-linear statistical model.

More preferably, the comparison step 40 is based on a model, trained on a data set and configured to predict the label of a new observation of the population. For example, for the purposes of calibration, it is possible to use a data set coming from a set of individuals representative of a population, characterized by several reference statokinesigrams 111 and their associated parameters and / or reference quantifiers and by a binary label (label or class), for example of the form "good balance" / "bad balance". The data set can also include multiple labels. In the context of the present invention, the quantification method 1 can be based on at least twenty-five reference statokinesigrams 111, preferably at least fifty, and even more preferably at least one hundred.

The comparison step 40 includes the use of a supervised statistical learning model. In fact, the inventors have determined that, within the framework of the quantification method 1 according to the invention, the best quantification results are obtained from methods based on principles of supervised statistical learning, preferably methods adapted to multivariate data. .

Within supervised learning methods, the inventors have identified certain more effective treatment methods. This could be linked to the fact that the quantifiers resulting from the method according to the invention come from data sets exhibiting a large imbalance and generally non-uniform metrics. Thus, preferably, this comparison step 40 is carried out via various non-linear supervised statistical learning methods. It can for example be cited:

kernel methods (e.g. Large Margin Separators - Support Vector Machines SVM, Kernel Ridge Regression) described for example in Burges, 1998 (Data Mining and Knowledge Discovery. A Tutorial on Support Vector Machines for Pattern Recognition).

Ref: 0504-064a the methods of sets (eg Bagging, Boosting, decision trees, Random Forest) described for example in Brieman, 2001 (Machine Learning. Random Forests), or the neural networks described for example in Rosenblatt, 1958 (The perceptron: a probabilistic model for information storage and organization in the brain).

As discussed above, the aim of the method according to the invention, beyond the prediction of belonging to a group of individuals, is to quantify an equilibrium, that is to say to associate a quantified value or an equilibrium quality level of an individual. Thus, the quantification method 1 according to the invention comprises a step 50 of determining a representative value 160 of the balance of the individual on the basis of the results of the comparison step 40.

Preferably, the representative value 160 can be based on the definition of an order relation on the population in order to prioritize the individuals who compose it. This step can be designated by the term binary scheduling. In practice, the binary ordering problem consists in learning a model, from a sample Sn = {(Xi, Yi), 1 <i <n} of copy of the couple (X, Y) in order to order the minus a new observation X _o of the random variable X, for which the label Y _o is not known. Such a model makes it possible to order the new observations by positioning at the top of the classification the observations having the highest probability of being positive and at the bottom of the classification the most probably negative observations.

Alternatively, the assignment of this representative value 160 can be based on several statistical methods such as SVMs with flexible margins or Gaussian Mixture Models.

Preferably, the quantification method 1 of the balance according to the invention includes the use of a notation algorithm 500 which can be integrated into a data processing module 220 and configured to implement:

the step 40 of comparing the values of several quantifiers 130 with the values of the same quantifiers obtained from reference statokinesigrams 111, and

- the step of determining 50 of a representative value 160 of the balance of the individual at the end of the comparison.

This 500 scoring algorithm may have been constructed from different supervised learning models. Even more preferably, this algorithm of

Ref: 0504-064a notation 500 is based on a supervised statistical learning model configured so as to minimize a risk of the scheduling rule and thus making it possible to obtain more efficient prediction rules such as the methods: Rankboost, Adarank, Rank SVM, Lambda rank, Ranking Forest or neural network.

Even more preferably, the scoring algorithm 500 was constructed from a combination of several nonlinear supervised statistical learning models. Thus, preferably, the creation of the scoring algorithm 500 a includes a "Bagging" step and / or a Boosting step. For example, the 500 scoring algorithm can include several Ranking trees constructed using a Bagging step. Indeed, the notation algorithms developed by the inventors in the context of the present invention are very effective if they incorporate a Bagging step.

Even more preferably, the previously calibrated 500 rating algorithm was obtained by the implementation of a Ranking Forest or Random Forest method.

Bagging, or Bootstrap Aggregating is a method of training a learning algorithm on different subsets of the initial learning set. In practice, we generate B subsets by drawing each of them randomly N times with delivery to the initial learning set. The subsets are called bootstrap samples. Bagging and its implementation are described in detail in Galar et al 2011 (A Review on Ensembles for the Class Imbalance Problem: Bagging-, Boosting-, and Hybrid-Based Approaches). Bagging is very effective in combination with learning algorithms such as decision trees and the inventors have also discovered that the underbagging method is particularly well suited to the method according to the invention.

Boosting includes a set of algorithms such as: Adaboost, LPBoost, TotalBoost, BrownBoost, xgboost, MadaBoost, LogitBoost. Boosting refers to a method consisting in training a learning algorithm in order to produce precise decisions by combining "weak" decision rules (ie able to recognize two classes at least as well as chance would) . Boosting allows, through successive iterations of weak rules, the generation of a strong classification, or decision rule. Boosting is therefore a sequential method and each sample is drawn according to the performance of the basic rule on the previous sample. Boosting and its implementation are described in detail in

Ref: 0504-064a

Freund & Schapire 1999 (Machine Learning Large. Margin Classification Using the Perceptron Algorithm).

Random forest analysis is one of the methods of supervised statistical learning. It is based on the principle of Bagging, the originality of the analysis is the aggregation of K trees constructed with a small number of variables. Each node is constructed with a small number of variables but always constant and chosen randomly. For example, several independent models are built to predict the same variable Y and then the predictions of these models are aggregated. This aggregation of independent models reduces the variance and therefore reduces the prediction error.

Preferably, the quantification method 1 according to the invention makes it possible to obtain a quantification of the balance in the form of a score or a value between zero and one hundred, proportional to the quality of the balance . For example, a value less than 30 indicates a weak equilibrium. Preferably, the step of determining an equilibrium value on the basis of the results of the comparison is followed by a step of recording 60 of the representative value 160 of the balance obtained and possibly the association of said value with a unique identifier linked to said individual.

[00101] Thus, this allows the individual to compare his representative value of the equilibrium 160 over time. Thus, preferably, the quantification method 1 according to the invention can be implemented in the same individual on different dates so as to follow the evolution of its value representative of the equilibrium 160 and therefore of the quality of its balance.

As shown in Figure 1, the quantification method 1 of the balance according to the invention can also include a step of graphical representation 70 of said value representative of the balance 160. The value can be the subject of a display via a display module 340a. This display can be a simple display indicating a value or a graphical representation.

This graphical representation can represent the evolution of the value representative of equilibrium 160 over time or the placement of this value within its own group of individuals.

Ref: 0504-064a [00104] Said value representative of the balance 160 can also be transmitted on remote systems such as tablets, servers or personal computers. Thus, the quantification method 1 according to the invention may comprise a step of transmitting the value representative of the balance 160, of the calculated quantifiers and / or of the parameters calculated towards at least one communicating system such as a tablet, a server or a computer, via at least one communication network.

Preferably, the invention relates to a method of quantification 1 of the equilibrium comprising the quantification of the static equilibrium and of the dynamic equilibrium. Even more preferably, the invention relates to the quantification of the static equilibrium.

As part of the development of this new equilibrium quantification method 1, the inventors verified the relevance of the value representative of the equilibrium 160 obtained via the statistical models developed and in particular the rating algorithms used by the intermediate of ROC curves. The statistical models developed and in particular the 500 rating algorithms used by the inventors make it possible to obtain AUCs greater than 0.7, preferably greater than 0.8.

Figure 6 shows a particular embodiment of the invention. From this embodiment, the inventors analyzed the statokinesigrams of 49 individuals as presented in the examples.

FIG. 7 represents a decision tree according to the invention as constructed by a Ranking Forest model.

F1 and F2 correspond, within the meaning of the invention, to quantifiers relating to a parameter linked to the position 121 of the center of pressure. In addition, the 90th percentile of the ballistic interval is a particularly preferred quantifier within the meaning of the invention. F3 corresponds to a quantifier relating to the stability 122 of the pressure center. The combination of these quantifiers by means of a notation algorithm 500 makes it possible to generate a representative value 160 of the equilibrium (e.g. 0; 0.33; 0.66; 1).

Ref: 0504-064a According to one aspect, the invention relates to a device 2 for quantifying the balance capable of implementing the method 1 for quantifying the balance according to the invention.

More particularly, the device 2 for quantifying the balance according to the invention comprises:

- a communication module 210, capable of receiving a statokinesigram

110 of said individual,

a storage means 280, and

- a data processing module 220.

A device for quantifying the equilibrium 2 according to the invention is shown diagrammatically in FIG. 8. These modules are distinct in FIG. 8 but the invention can provide various types of arrangement such as for example a single cumulative module all the functions described here. These modules can be divided into several electronic cards or combined on a single electronic card.

The communication module 210 is configured to receive and transmit information to remote systems such as platforms, tablets, telephones, computers or servers. The communication module allows data to be transmitted over at least one communication network and can include wired or wireless communication. Preferably, the communication is carried out via a wireless protocol such as wifi, 3G, 4G, and / or Bluetooth.

The communication module 210 allows for example to receive the raw displacement center pressure data or statokinesigrams. It is also configured to send the data relating to the calculated parameters, to the calculated quantifiers and to the value representative of the equilibrium 160. These data exchanges can take the form of sending and receiving files containing the raw values of the pressure sensors. , of files containing the coordinates of the trajectory of the center of pressure, and of files comprising the parameters, the quantifiers and the values representative of the balance 160 determined from the statokinesigram 110.

The data exchanged can preferably be transferred in an encrypted manner and associated with a specific key of the individual studied.

The data processing module 220 is configured to:

• Extract, from a statokinesigram 110 of an individual transmitted by the communication module 210, values of at least one trajectory parameter

Ref: 0504-064a relating to the position 121 of the pressure center and the values of at least one trajectory parameter linked to the stability 122 of the pressure center, • Determine several quantifiers 130, from the values of the trajectory parameters 121 , 122 extracted, • Compare the values of said quantifiers 130 with the values of the same quantifiers obtained from reference statokinesigrams 111, and • Determine a value 160 representative of the equilibrium of the individual on the basis of said comparison.

The data processing module 220 advantageously includes a processor and is able to connect to a storage means 280.

The storage means 280 may include a transient memory and / or a non-transient memory. It is suitable for recording, for example in the form of files, the raw values of the pressure sensors, the coordinates of the trajectory of the pressure center, the parameters 120, the quantifiers 130 and the values representative of the balance 160 determined at from the statokinesigram (s) 110. The non-transient memory allows for example to save the configuration of the data processing module while the non-transient memory allows for example to save the statokinesigram 110. The non-transient memory can be a medium such as a CDrom, a memory card, or a hard disk hosted by a remote server.

Preferably, the data processing module 220 is configured to implement the different steps of the quantification method 1 according to the invention. Thus, the preferred steps of the quantification method 1 of the balance according to the invention are also preferred configurations for the data processing module 220 according to the invention.

The quantification device 2 according to the invention may also include a module 230 for generating a statokinesigram 110. This module is configured to generate the data relating to a statokinesigram 110 (eg position along the x and y axes as a function of time) ) from raw pressure center displacement data as it can be generated by force or pressure sensors.

The quantification device 2 according to the invention may also include a resampling module 240. In fact, the devices able to generate raw data for displacement of the center of pressure or statokinesigram 110 do not all offer a frequency controlled sampling. So some devices can

Ref: 0504-064a result in the generation of statokinesigram 110 having a first random frequency, the frequency of which cannot be predicted because it varies constantly during acquisition, for example understood, for the same statokinesigram 110, between 10 and 1000 Hz. However, such a frequency variation can lead to decreases in the performance of the quantization method 1 of the equilibrium according to the invention. Thus, preferably, the resampling module is configured to process the raw data or the statokinesigram 110 at a first frequency so as to generate statokinesigrams 110 resampled at a second frequency and having a substantially constant frequency. By substantially constant frequency, it is necessary to understand a frequency varying by less than 10% within the statokinesigram 110, preferably varying by less than 5%, even more preferably varying by less than 1%.

The statokinesigram 110 at a second frequency, generated by the resampling module 240, has a sampling frequency at least equal to 25 Hz. Preferably, the second frequency is substantially identical to the frequency of the reference statokinesigrams 111.

The equilibrium quantification device according to the invention may include a denoising module 290 configured to filter the raw data generated by the pressure or force sensors so as to reduce or eliminate the spurious signals. Denoising can be based on various methods such as denoising by wavelet, thresholding, Wiener filter and deconvolution.

The device can also include a control interface 260. This control interface is configured to allow the interaction of a user with the device for quantifying the balance. It can include, for example, manual actuators (e.g. buttons) or a touch screen capable of receiving user commands.

The device may also include a display module 270. This display module may include a liquid crystal screen. It makes it possible to display various information such as the results of the quantification, the value representative of the balance 160, the progression over time of said value and its positioning with respect to the values representative of the balance 160 within a group of people.

Ref: 0504-064a [00128] According to another aspect, the invention relates to a system for quantifying the equilibrium 3 shown in FIG. 9, suitable for implementing the quantification method 1 according to the invention. Preferably, the system for quantifying the balance 3 of an individual comprises:

a platform 310, said platform 310 being adapted to receive an individual and comprising pressure and / or force sensors 312 configured to generate raw data 313, at a first frequency, as a function of a pressure exerted by the feet of the on the platform 310,

a raw data processing unit 320, arranged to obtain at least one statokinesigram 110 of the individual from the raw data 313 generated by the platform 310, and

a device for quantifying the balance 2 described above, capable of communicating with the processing unit 320.

As shown in Figure 9, the platform 310 according to the invention is a support for receiving an individual and able to measure the displacement of a pressure center through force and / or pressure sensors . Any sensor system for measuring the center of pressure can be used. The only prerequisite is that the platform 310 is able to produce raw data making it possible to position the center of pressure. This support can, for example, be a pair of insoles, an “intelligent” floor equipped with a sensor or a balance. Preferably, the platform 310 comprises a plate 311. In general, the dimensions of one side of the plate 311 may be between 15 and 70 cm, preferably of the order of 25 to 40 cm. This plate 311 may for example include a template allowing reproducible positioning of the feet, between individuals and over time for the same individual. The platform 310 is configured to measure the pressure or the forces applied to the plate at a given instant and therefore includes sensors 312. The sensors will transform the force applied into an electrical, optical or magnetic signal corresponding to the raw data . This raw data can be combined and processed in order to specify the coordinates of the center of pressure and to follow its variations over time. These sensors can be pressure or force sensors. A force sensor measures the result of the support forces of a standing subject. The measurement of the forces and moments exerted on the platform makes it possible to specify the coordinates of the center of pressure and to follow its variations over time. A pressure sensor may for example include a pressure cell configured to measure or detect the pressure induced by the weight of the individual placed on the platform

Ref: 0504-064a or the pressure exerted by the feet of the individual on the platform. The data from these sensors is the raw data. The platform 310 can also include a plurality of resistive or piezoelectric sensors (for example between 1000 and 6000 sensors). The sensors are preferably 4 in number, and located at the ends of the platform, for example separated by 20 to 50 cm for the right and left or top and bottom sensors. For example, as shown in FIG. 9, the platform 310 includes four sensors 312 located at the four corners of the tray (Top left, Top right, Bottom left, Bottom right).

The platform 310 advantageously includes a time counting module and can be configured to measure the values of its various sensors 312 at random intervals, at a frequency which can vary for example from 10 Hz to 1000 Hz. Preferably, the platform 310 is configured to measure the values of its various sensors 312 at a frequency greater than or equal to 25 Hz, more preferably greater than or equal to 50 Hz.

Even more preferably, the platform 310 is configured to measure, during the acquisition of a statokinesigram 110, the values of its various sensors 312 at a frequency greater than or equal to 25 Hz and in a substantially constant manner. Indeed, if the sampling frequency is too low, or too random, the quantification of the balance will not be precise enough. If the frequency is not constant then preferably the average acquisition frequency is greater than or equal to 60 Hz, more preferably greater than or equal to 75 Hz.

The platform 310 may include a display device, preferably positioned so that the individual, standing on the tray 311 can see the display device.

The platform 310 can also include a loudspeaker device which can give instructions to the individual (e.g. getting on or off the tray 311). These instructions can also be given by the display device.

The platform 310 may also include a module for measuring the individual's weight, his fat, water, bone, muscle mass, his heart rate and / or his body mass index.

The equilibrium quantification system 3 also includes a raw data processing unit 320 generated by the platform. This raw data processing unit 320 is arranged and / or configured to generate at least one statokinesigram 110 of the individual from the raw data generated by the sensors 312. This raw data processing unit 320 can for example be

Ref: 0504-064a integrated into the platform 310 as shown in Figure 9. However, it can also be integrated into a remote server 330, to the quantification device 2 (eg it then integrates the statokinesigram generation module 230 therein 110) or to a control device 340.

The equilibrium quantification system 3 may include a remote server 330 as shown in FIG. 9. It is for example possible to access this remote server 330 via a web interface or directly via the appropriate functions directly implemented on a control device 340. All the communications between the control device (s) 340 and the remote server 330 can be secured for example by HTTPS protocols and AES 512 encryption.

This remote server can host the quantization device 2. Thus, a single quantification device 2 can follow a plurality of individuals.

The quantification system according to the invention may include a control device 340 of the system configured to interact with the platform 310 and the balance quantization device 2. This control device 340 of the system allows for example to control acquiring data from platform 310 and displaying the results from the quantification device 2.

This control device 340 of the system is present a mobile device such as a tablet 340a, a laptop, or a watch.

According to another aspect, the invention relates to a computer program product 4 configured to implement the quantification method 1 of the balance according to the invention. The computer program product 4 is recorded on a non-transient memory medium and is capable of being executed on a computer, a tablet or a server; said computer program comprising at least:

an algorithm suitable for extracting, from a statokinesigram 110 of an individual, values of at least one trajectory parameter relating to the position 121 of the center of pressure and values of at least one trajectory parameter related to stability 122 of the pressure center

an algorithm adapted to determine several quantifiers 130, from the values of the trajectory parameters 121, 122 extracted,

an algorithm suitable for comparing the values of said quantifiers 130 with the values of the same quantifiers obtained from reference statokinesigrams 111, and

Ref: 0504-064a

- an algorithm adapted to determine a value 160 representative of the equilibrium of the individual on the basis of said comparison.

More preferably, the computer program product 4 is recorded on a non-transient memory medium and is capable of being executed on a computer, a tablet or a server; said computer program comprising at least:

an algorithm suitable for extracting, from a statokinesigram 110 of an individual, values of at least one trajectory parameter relating to the position 121 of the center of pressure, values of at least one trajectory parameter linked to the stability 122 of the center of pressure and the values of at least one trajectory parameter linked to the dynamics 123 of the center of pressure

an algorithm adapted to determine several quantifiers 130, from the values of the trajectory parameters 121, 122, 123 extracted, and

a notation algorithm suitable for comparing the values of several quantifiers 130 and determining a value 160 representative of the balance of the individual on the basis of said comparison [00143] The method, the device, the system and the program product d computer according to the invention allow the quantification of the balance of an individual and can have many applications.

In fact, the invention makes it possible to provide a measurement tool, namely a method, the device for implementing the method and the system integrating the device, which makes it possible to obtain a quantified and objective value of the balance of an individual in order to answer three main questions relating to the balance of an individual:

- A] the evolution of balance, natural or under treatment,

- B] the quality of the balance and therefore, its corollary, the severity of a possible balance disorder (e.g. what is the risk of falling?), And

- C] the cause (s) of the possible balance disorder.

Indeed, the generation of a value representative of the balance 160 of an individual and indicative of the quality of his balance allows the individual, or other people, to assign a quantified value and objective to this balance.

These values or these scores can be used in the context of time monitoring aimed at identifying deviations from the learned reference.

Similarly, the invention can be used to highlight the effects of different treatments and the recovery rate could be followed by the quantification of

Ref: 0504-064 has the balance according to the invention. Thus, the invention can be implemented in the context of the evaluation of the performance of a sports program, prostheses, sports shoes, compensating soles, rehabilitation protocols, treatment of neurological disorders and / or surgical techniques. The process according to the invention is particularly suitable for the elderly. In addition, the invention can be used to compare the quality of the balance of an individual with the quality of the balance of other individuals and to determine by example if this individual is at risk of falling. Thus, the invention can be implemented as part of the measurement of a risk of fall, for example at 6 months. In this context, the value representative of the balance 160 determined by the quantification method 1 according to the invention, a value indicative of a risk of fall at 6 months. In particular, the individual within the meaning of the invention is a person over 60 years old, preferably over 70 years old.

In addition, comparing the values of the quantifiers 130 obtained from an individual to values of the quantifiers obtained from different categories of people can make it possible to target the care of individuals and to direct them towards the appropriate services (eg trauma, rheumatology, neurology). Thus, the invention can be implemented in the context of determining the origin of the balance disorder.

Examples [00150] Individuals studied [00151] The results presented below were carried out according to a protocol approved by the National Agency for the Safety of Medicines and Health Products and written consent was obtained for all of the participants.

The invention was implemented on a group of 49 individuals with the following characteristics:

- over the age of 70;

- able to stand on the platform,

BMI less than 21 at the time of the consultation, and gave informed consent.

Among the 49 individuals included in the study:

- 27 declared a fall during the 6 months preceding the consultation,

Ref: 0504-064a

- 7 falls led to trauma and hospitalization, led to trauma and no hospitalization, and

- 4 were classified as benign (no trauma, no hospitalization).

Measurement of the displacement of the pressure center [00155] During the consultation, the displacements of the pressure center of the individuals were monitored using a Wii Balance Board (registered trademark) and recorded using a personalized application specially developed in the part of the invention. The feet were positioned in the most comfortable position for the patient, without exceeding the width of the shoulders. The trajectory of the center of pressure was recorded for 20 seconds with eyes open, then 20 seconds with eyes closed. A fall questionnaire was completed for each individual to record the falls reported to have occurred in the past 6 months.

Pretreatment Before calculating the statokinesigrams, the output of the raw signals by the WBB were de-noised and resampled.

Statistical analysis.

For each statokinesigram, fifteen quantifiers were calculated from the statokinesigrams.

The quantifiers obtained from the statokinesigrams of the references make it possible to configure a rating algorithm based on a Ranking Forest algorithm such as the sub-part of a decision tree represented in FIG. 7. F1 corresponds to the closed eyes / eyes open for the 90th percentile of the ballistic interval, F2 is the ratio eyes closed / eyes open for the variance of the position on the Y axis and F3 is the variance of the temporal balance with eyes closed. The quantifiers obtained from a statokinesigram to be analyzed serve as input for this scoring algorithm which calculates a value, between 0 and 1, indicative of the balance and more particularly of the risk of falling of the individual. A low score corresponds to a high risk of falling, while a high score is characteristic of a low risk of falling.

[00161] Thus, unlike the prior art, the invention provides a measurement tool making it possible to obtain a quantified and objective value for the balance of an individual.

Ref: 0504-064a

Claims (10)

Claims 1. Method for quantifying the balance of an individual to obtain a value representative (160) of the balance of said individual, said method being implemented by a device comprising at least one data processing module (220) connected storage means (280) and said method comprising: a) a step of recording (10), on the storage means (280), of at least one statokinesigram of the individual (110) obtained from a platform (310) comprising sensors (312) of pressure and / or force, b) an extraction step (20), by the data processing module (220) and from the statokinesigram (s) of the individual (110) recorded on the storage means (280) , values of at least one trajectory parameter relating to the position (121) of the center of pressure and values of at least one trajectory parameter relating to the stability (122) of the center of pressure, c) a step of determining (30), by the data processing module (220), the value of several quantifiers (130), from the values of the trajectory parameters (121, 122) extracted in step b ), d) a step of comparison (40), by the data processing module (220), of said values of several quantifiers (130) with the values of the same quantifiers obtained from reference statokinesigrams (111), and e) a step of determining (50), by the data processing module (220), of said representative value (160) of the balance of the individual at the end of the comparison (40). 2. Quantification method according to claim 1, characterized in that step b) further comprises the extraction (21) of the values of at least one trajectory parameter relating to the dynamics (123) of the center of pressure. 3. Quantification method according to one of claims 1 or 2, characterized in that step b) is carried out from two statokinesigrams (110) generated during a Romberg test. Ref: 0504-064a 4. Quantification method according to any one of claims 1 to 3, characterized in that at least one of the quantifiers (130) determined in step c) is an extreme value of said trajectory parameter (121, 122, 123 ), said extreme value corresponding to a percentile between a percentile greater than or equal to 5 and a percentile less than or equal to 15, or else to a percentile comprised between a percentile greater than or equal to 85 and comprised between a percentile less than or equal to 95, values of the trajectory parameter (121, 122, 123). 5. Quantification method according to any one of claims 1 to 4, characterized in that steps d) and e) are carried out by implementing the values of the quantizers (130) determined in step c) in an algorithm notation (500) previously calibrated on the basis of the values of the same quantifiers obtained from the reference statokinesigrams (111). 6. Quantification method according to claim 5, in which the grading algorithm (500) previously calibrated was obtained by the implementation of a statistical method of supervised learning, preferably a RANKING FOREST or RANDOM method. FOREST. 7. Quantification method according to one of claims 5 or 6, in which the previously calibrated notation algorithm (500) was obtained by the implementation of a statistical method of supervised learning comprising the implementation of 'a stage of Bagging. 8. A quantification method according to any one of claims 1 to 7, characterized in that it comprises in step c) determining the value of at least five quantifiers (130). 9. Device for quantifying (2) the balance of an individual, said device comprising: a communication module (210) capable of receiving a statokinesigram (110) of said individual, a storage means (280) capable of recording the statokinesigram (110), and - at least one data processing module (220), able to connect to the storage means (280), said data processing module (220) being configured to: Ref: 0504-064a o Extract, from a statokinesigram (110) of said individual transmitted by the communication module (210), values of at least one trajectory parameter relating to the position (121) of the center of pressure and values of at least one trajectory parameter linked to the stability (122) of the pressure center, o Determine several quantifiers (130), from the values of the extracted trajectory parameters (121, 122), o Compare the values said quantifiers (130) to the values of the same quantifiers obtained from reference statokinesigrams (111), and o Determine a value (160) representative of the balance of the individual on the basis of said comparison. 10. System for quantifying (3) the balance of an individual, comprising: - a platform (310), said platform (310) being adapted to receive an individual and comprising pressure and / or force sensors (312) configured to generate raw data (313), at a first frequency, function of pressure exerted by the feet of the individual on the platform (310), a raw data processing unit (320), arranged to obtain at least one statokinesigram (110) of the individual from the raw data (313) generated by the platform (310), and - a device for quantifying the balance according to claim 9, capable of communicating with the processing unit (320). Ref: 0504-064a 1/6