WO2019219961A1

WO2019219961A1 - A method and a system for analyzing an asymmetric movement pattern of a subject

Info

Publication number: WO2019219961A1
Application number: PCT/EP2019/062904
Authority: WO
Inventors: Andreas Jakobsson; Johan SWÄRD
Original assignee: Medotemic Ab
Priority date: 2018-05-18
Filing date: 2019-05-20
Publication date: 2019-11-21

Abstract

A method for analyzing an asymmetric movement pattern of a subject, such as a person or an animal, the method (300) comprising: obtaining time-resolved data (110, 210) representing the movement of said subject, transforming (302) the time-resolved data (110, 210) to a frequency-resolved representation (120, 220) of the time-resolved data (110, 210), determining (304) one or more markers representative of the asymmetric movement pattern, wherein the one or more markers are based on one or more features in the time-resolved data (110, 210) and/or on one or more features in the frequency-resolved representation (120, 220) of the time-resolved data (110, 210), and creating (306) an index representing a degree of asymmetry of the asymmetric movement pattern based on the one or more markers.

Description

A method and a system for analyzing an asymmetric movement pattern of a subject

The present invention relates to a method and a system for analyzing an asymmetric movement pattern of a subject.

Background of invention

Accurately determining an asymmetry in the movement of a person or an animal is typically a long and tedious process which often involves a visit to a specialized test center. In order to accurately determine the asymmetry, multiple visits to the test center, where each visit may last for several hours, are often required. Such repeated recordings can, however, still fail to record specific features of the asymmetry, for instance when the movement is varying over time. Also, the movement of a test subject is typically different in a test environment as the test subject may be fitted with a lot of awkward measuring equipment and general being nervous and out of his or her comfort zone. Such a test may easily result in an inaccurate determined movement of the test subject.

Hence there is a need for determining the movement of a person or an animal in a simpler and less time-consuming manner.

Summary of invention

It is an object of the present inventive concept to at least reduce the above problems, and to provide a method and a system for analyzing an asymmetric movement pattern of a subject, preferably by creating an index of an asymmetric movement pattern. The method may be a computer-implemented method.

According to a first aspect, the above and other objects are achieved by a method for analyzing an asymmetric movement pattern of a subject, such as a person or an animal, the method (300) comprising:

- obtaining time-resolved data (1 10, 210) representing the movement of said subject,

- transforming (302) the time-resolved data (1 10, 210) to a frequency- resolved representation (120, 220) of the time-resolved data (1 10, 210), - determining (304) one or more markers representative of the asymmetric movement pattern, wherein the one or more markers are based on one or more features in the time-resolved data (1 10, 210) and/or on one or more features in the frequency-resolved representation (120, 220) of the time- resolved data (1 10, 210), and

- creating (306) an index representing a degree of asymmetry of the

asymmetric movement pattern based on the one or more markers.

The method may, in particular, be a method for analyzing gait. The method may also be a method for creating an index of an asymmetric movement pattern, comprising: transforming time-resolved data to a frequency-resolved representation of the time- resolved data, determining one or more markers representative of the asymmetric movement pattern, wherein the one or more markers are based on one or more features in the time-resolved data and/or on one or more features in the frequency- resolved representation of the time-resolved data, and creating the index of the asymmetric movement pattern based on the one or more markers.

The time-resolved data may comprise time-resolved acceleration data. Preferably, the time-resolved acceleration data is obtained from a device, such as a handheld electronic device, which is, preferably worn or carried by the subject. The time-resolved data may comprise time-resolved gyro data. Preferably, the time-resolved gyro data is obtained from a device, such as a handheld electronic device, which is, preferably worn or carried by the subject.

By means of the present method it is possible to create a reproducible index of an asymmetric movement pattern, and to determine a degree of asymmetry in the asymmetric movement pattern. A reproducible index of the asymmetric movement pattern in turn enables a comparison of asymmetric movement patterns relating to different occasions. The index may represent a degree of asymmetry of the asymmetric movement pattern. The time-resolved data may be related to the asymmetric movement pattern.

According to the present method, time-resolved data is transformed to a frequency- resolved representation of the time-resolved data. The transformation may comprise a discrete cosine transform (DOT). The transformation may comprise a wavelet transform. The transformation may comprise a Fourier transform. The Fourier transform may be a discrete Fourier transform (DFT). Preferentially, the transformation comprises a fast Fourier transform (FFT).

An advantage of transforming time-resolved data to the frequency-resolved

representation of the time-resolved data is that dominant frequencies of the asymmetric movement pattern may be determined.

According to the present method, one or more markers representative of the

asymmetric movement pattern is determined. This may be advantageous since the one or more markers may be used to determine a degree of asymmetry in the movement pattern.

The one or more markers are based on one or more features in the time-resolved data and/or on one or more features in the frequency-resolved representation of the time- resolved data. In other words, the markers may be based on features in the time- resolved data, the frequency-resolved representation of the time-resolved data, or both. For example, the features in the time-resolved data may comprise a number of local extrema, and a moment of the time-resolved data. For example, a moment of the time- resolved data may be a variance of the time-resolved data. The features in the frequency-resolved representation of the time-resolved data may, for instance, be a number of local extrema, a ratio between amplitudes of local extrema, a moment of the frequency-resolved representation of the time-resolved data, or a linear combination of amplitudes of local extrema.

An advantage of basing the one or more markers on one or more features in the time- resolved data and/or the frequency-resolved representation of the time-resolved data may be that the one or more markers are a better representation of the asymmetric movement pattern.

An advantage of basing the one or more markers on one or more features in the time- resolved data and the frequency-resolved representation of the time-resolved data may be that the one or more markers are a more robust representation of the asymmetric movement pattern.

According to the present method, the index of the asymmetric movement pattern is created based on the one or more markers. In other words, the index is a composite statistic based on the one or more markers. The index of the asymmetric movement pattern may aggregate the one or more markers. The index of the asymmetric movement pattern may be a sum of the one or more markers. The index of the asymmetric movement pattern may be a weighted sum of the one or more markers.

An advantage of creating the index of the asymmetric movement pattern based on the one or more markers may be that the index is based on the degree of asymmetry in the movement pattern. In other words, the index may summarize and rank the asymmetry in the movement pattern.

In one embodiment of the presently disclosed method for analyzing an asymmetric movement pattern of a subject, each marker constitutes a dimension in a

multidimensional space, and wherein the markers are translated to a combined marker representative of the asymmetric movement pattern by projecting the markers from the multidimensional space to a one-dimensional representation. Each marker may thereby constitute one dimension in a multidimensional space. A linear combination of markers may also constitute one dimension in the multidimensional space. During training the markers are projected from the multidimensional space to a one-dimensional space, wherein two clusters may be identified: one cluster which is considered to have a normal or symmetric movement and one cluster characterized by asymmetric movement, such as limping. The markers may also be projected to a space of higher dimensions than one. Preferably, the projection to the one-dimensional space is performed such that maximum separation of the two clusters is achieved. The projection may apply linear or non-linear discriminant analysis, for example Fisher linear discriminant, using non-linear or linear classifiers for separation of the two clusters. Therefore, in one embodiment of the presently disclosed method for analyzing an asymmetric movement pattern of a subject, an asymmetry reference level is represented by two clusters of training data projected from the multidimensional space to the one-dimensional representation, wherein the asymmetry reference level is a level between two clusters of training data in the one-dimensional representation. This may correspond to a point in the one-dimensional representation having equal distance to the two training clusters. Hence, the asymmetry reference level may be selected as a level having equal distance to the two clusters of training data. In the presently disclosed method a check may be performed as a first step determining whether a movement is symmetric or asymmetric. If the measurement, and in particular the one or more markers projected to the one-dimensional space, is closer to the asymmetric group, the measurement is considered to be asymmetric. In this case the calculated index may be calculated as a distance between the one or more markers projected to the one-dimensional space and the asymmetry reference level. A projected point close to the asymmetry reference level may, in this regard, correspond to a low index of asymmetry, whereas a projected point at a greater distance from the asymmetry reference level may correspond to a high index of asymmetry.

The one or more features in the time-resolved data (1 10, 210) and/or frequency- resolved representation (120, 220) of the time-resolved data (1 10, 210) may further comprise a correlation of the acceleration data and/or gyro data. The correlation may thereby form a separate dimension, which can be combined in a linear or non-linear manner with other features.

According to one embodiment of the presently disclosed method for analyzing an asymmetric movement pattern of a subject, acceleration data from the accelerometer (428) is evaluated to determine at least one interval of the time-resolved data (1 10, 210) that corresponds to gait of the subject, and using the time-resolved-data (1 10, 210) of the interval in the step of determining (304) the one or more markers representative of the asymmetric movement pattern.

Preferably, after the step of evaluating acceleration data from the accelerometer (428) to determine at least one interval of the time-resolved data (1 10, 210) that corresponds to gait of the subject, which may be performed at predefined intervals, a frequency domain representation of a combination of accelerometer and gyro data is extracted. Fig. 2A and B show time-resolved acceleration data (2A) and corresponding frequency domain representation (2B) for a limping subject. Fig. 1 A and B show time-resolved acceleration data (1 A) and corresponding frequency domain representation (1 B) for a subject having symmetric movement. The subject associated with symmetric movement has a more repetitive pattern in the acceleration data and more

distinguished peaks in the spectrum. Based on these diagrams, markers indicative of the asymmetric movement pattern can be determined, which is described in further detail below.

The time-resolved data may comprise time-resolved acceleration data, which may be advantageous since the time-resolved acceleration data relates to acceleration components of the asymmetric movement pattern. A further advantage may be to use the time-resolved acceleration data to transform a coordinate system of the time-resolved data.

A further advantage may be to use the time-resolved acceleration data to transform a coordinate system of the time-resolved acceleration data.

The time-resolved data may further comprise time-resolved gyro data, which may be advantageous since the time-resolved gyro data relates to rotational components of the asymmetric movement pattern.

A further advantage may be to use the time-resolved gyro data to transform a coordinate system of the time-resolved data.

A further advantage may be to use the time-resolved gyro data to transform a coordinate system of the time-resolved acceleration data.

The one or more features in the time-resolved data may comprise: a number of local extrema in the time-resolved data, and a moment of the time-resolved data. It may be advantageous to base the one or more markers on any one of these features since these features relate to the asymmetry of the movement pattern.

The one or more features in the frequency-resolved representation of the time-resolved data may comprise: a number of local extrema in the frequency-resolved

representation of the time-resolved data, a ratio between amplitudes of local extrema in the frequency-resolved representation of the time-resolved data, a moment of the frequency-resolved representation of the time-resolved data, and a linear combination of amplitudes of local extrema in the frequency-resolved representation of the time- resolved data. It may be advantageous to base the one or more markers on any one of these features since these features relate to the asymmetry of the movement pattern.

The one or more features in the frequency-resolved representation of the time-resolved data may comprise a number of local maxima for the gyro data. The variance for this frequency representation may be larger for subjects having asymmetric movement, such as limping. Moreover, the variance of low-pass filtered combination of acceleration and gyro measurement may be indicative of a higher degree of asymmetry, thus a higher index.

A further feature may be maximum correlation periodicity for the acceleration data and the gyro data in any of the dimensions in the multidimensional space.

The one or more features in the time-resolved data may be one or more features in one or more subsets of the time-resolved data. The one or more features in the frequency- resolved representation of the time-resolved data may be one or more features in one or more subsets of the frequency-resolved representation of the time-resolved data.

It may be advantageous to base the one or more markers on one or more features in one or more subsets of the time-resolved data, since it may reduce related

computational costs, bandwidths, and/or memory requirements. A further advantage is that a reduction of network usage of a handheld electronic device used for recording the time-resolved data may reduce the energy consumption of the handheld electronic device.

It may be advantageous to base the one or more markers on one or more features in one or more subsets of the frequency-resolved representation of the time-resolved data, since it may reduce related computational costs, bandwidths, and/or memory requirements.

The one or more markers may be at least two different markers, which may be advantageous since it results in a more robust index of the asymmetric movement pattern. Each marker may constitute a dimension in a

multidimensional space. The markers may then be translated to a combined marker representative of the asymmetric movement pattern by projecting the markers from the multidimensional space to a one-dimensional representation. The index may then be calculated as a distance between the reference level and the combined marker.

A further advantage if the one or more markers are at least two different markers may be that the created index becomes a better representation of the asymmetry in the asymmetric movement pattern. The method may further comprise: filtering the time-resolved data through a bandpass filter and determining a measure of an energy of the filtered time-resolved data.

It may be advantageous to bandpass filter the time-resolved data since it may reduce noise in the time-resolved data. A further advantage to bandpass filter the time- resolved data may be an improvement of the time-resolved data.

The method may further comprise: checking if a moment of the time-resolved data is above a predetermined threshold, and checking if a dominant frequency of the frequency-resolved representation of the time-resolved data is above a predetermined frequency threshold.

According to a second aspect the present disclosure relates to a movement analysis system for analysis of an asymmetric movement pattern of a subject. The system comprises: a processor configured to: obtain time-resolved data (1 10, 210)

representing the movement of said subject, transform the time-resolved data to a frequency-resolved representation of the time-resolved data, determine one or more markers representative of an asymmetric movement pattern for the user of the handheld electronic device, wherein the one or more markers are based on one or more features chosen from the group of features consisting of: a number of local extrema in the time-resolved data, a moment of the time-resolved data, a number of local extrema in the frequency-resolved representation of the time-resolved data, a ratio between amplitudes of local extrema in the frequency-resolved representation of the time-resolved data, a moment of the frequency-resolved representation of the time- resolved data, and a linear combination of amplitudes of local extrema in the frequency-resolved representation of the time-resolved data, and create an index of the asymmetric movement pattern based on the one or more markers. The system may further comprise a non-transitory computer-readable recording medium having recorded thereon a program which is executable on a handheld electronic device having processing capabilities, wherein the program comprises program code portions which when executed on the handheld electronic device is configured to: establish a communication channel between the handheld electronic device on which the program is executed and the server, evaluate acceleration data from an accelerometer of the handheld electronic device to determine if a user of the handheld electronic device is moving, as long as it is determined that the user is moving, transmit, via the

communication channel, time-resolved data from the handheld electronic device. One option is to transmit data from the handheld electronic device and process data in substantially real-time.

The system comprises a server comprising a processor and a non-transitory computer- readable recording medium having recorded thereon a program which is executable on a handheld electronic device having processing capabilities. The server may be a stationary electronic device or a mobile electronic device. The handheld electronic device may be any kind of wearable electronic device, such as a mobile phone, a smartphone or a smartwatch.

The program comprises program code portions which when executed on the handheld electronic device is configured to: establish a communication channel between the handheld electronic device on which the program is executed and the server. In other words, the handheld electronic device and the server may communicate with each other. The communication channel may be a wired or wireless communication channel. The wireless communication channel may be cellular radio (e.g. 3G, 4G, 5G), Wi-Fi, Bluetooth, NFC, or any other dedicated protocol for wireless communication.

The program comprises program code portions which when executed on the handheld electronic device is further configured to: evaluate acceleration data from an

accelerometer of the handheld electronic device to determine if a user of the handheld electronic device is moving, and as long as it is determined that the user is moving, transmit, via the communication channel, time-resolved data from the handheld electronic device. In other words, time-resolved data is transmitted from the handheld electronic device to the server as long as the program code portions determines that the user of the handheld electronic device is moving. This may be advantageous since it reduces an amount of time-resolved data sent from the handheld electronic device to the server. In other words, an advantage may be a reduction of computational costs, bandwidths and/or memory requirements related to the amount of time-resolved data received by the server. A further advantage is that a reduction of network usage of the handheld electronic device may reduce the energy consumption of the handheld electronic device.

The processor of the server is configured to: transform the time-resolved data to a frequency-resolved representation of the time-resolved data and determine one or more markers representative of an asymmetric movement pattern for the user of the handheld electronic device. The time-resolved data may be transformed to a frequency-resolved representation of the time-resolved data by means of Fourier transformation. For example, the resulting Fourier transform may be a discrete Fourier transform (DFT). Preferentially, the resulting Fourier transform is a fast Fourier transform (FFT). The one or more markers are based on one or more features chosen from the group of features consisting of: a number of local extrema in the time-resolved data, a moment of the time-resolved data, a number of local extrema in the frequency- resolved representation of the time-resolved data, a ratio between amplitudes of local extrema in the frequency-resolved representation of the time-resolved data, a moment of the frequency-resolved representation of the time-resolved data, and a linear combination of amplitudes of local extrema in the frequency-resolved representation of the time-resolved data.

The processor of the server is further configured to create an index of the asymmetric movement pattern based on the one or more markers.

In general, features of this aspect of the inventive concept provide similar advantages as discussed above in relation to the previous aspect of the invention, why said advantages will not be repeated in detail to avoid undue repetition.

The time-resolved data may comprise time-resolved acceleration data.

The time-resolved data may comprise time-resolved gyro data.

The processor of the server may further be configured to: filter the time-resolved data from the handheld electronic device through a bandpass filter, and determine a measure of an energy of the filtered time-resolved data.

The program may comprise program code portions which when executed on the handheld electronic device is further configured to evaluate if a user of the handheld electronic device is moving by, for a predetermined time period of the time-resolved acceleration data: check if a moment of the time-resolved data is above a

predetermined threshold. In other words, the program code portions, when executed, may determine that the user of the handheld electronic device is moving if the user of the handheld electronic device moves for a time longer than the predetermined time period. This may be advantageous since it reduces the amount of time-resolved data sent from the handheld electronic device to the server. In other words, an advantage may be a reduction of computational costs, bandwidths and/or memory requirements related to the amount of time-resolved data received by the server. A further advantage is that a reduction of network usage of the handheld electronic device may reduce the energy consumption of the handheld electronic device.

The predetermined time period of the acceleration data may be in the range of 1 -10 seconds, preferably 5 seconds.

The handheld electronic device may be a smart wearable electronic device, such as a smartphone and/or a smartwatch, which is advantageous since it may reduce costs associated with the creation of the index of the asymmetric movement pattern. A further advantage is that a smartphone or a smartwatch may gather time-resolved data for longer time periods. Further advantages are that a smartphone or a smartwatch may gather time-resolved data for a plurality of different situations and/or during normal behavior of the user of the handheld electronic device. In other words, the user of the handheld electronic device may not need to be aware that time-resolved data is gathered.

The program may be an application downloadable to the smartphone via an application providing service.

A further scope of applicability of the present invention will become apparent from the detailed description given below. However, it should be understood that the detailed description and specific examples, while indicating preferred variants of the present inventive concept, are given by way of illustration only, since various changes and modifications within the scope of the inventive concept will become apparent to those skilled in the art from this detailed description.

Hence, it is to be understood that this invention is not limited to the particular steps of the methods described as such method may vary. It is also to be understood that the terminology used herein is for purpose of describing particular embodiments only, and is not intended to be limiting. It must be noted that, as used in the specification and the appended claims, the articles“a”,“an”,“the”, and“said” are intended to mean that there are one or more of the elements unless the context clearly dictates otherwise. Thus, for example, reference to“a unit” or“the unit” may include several devices, and the like. Furthermore, the words“comprising”,“including”, and similar wordings does not exclude other steps.

Description of drawings

The aspects of the present inventive concept will now be described in more detail, with reference to the appended drawings. The figures are provided to illustrate the general structures of the present inventive concept. As illustrated in the figures, the sizes of layers and regions are exaggerated for illustrative purposes and, thus, are provided to illustrate the general structures of the present invention. Like reference numerals refer to like elements throughout.

Figure 1 A is a graphical representation of a subset of time-resolved data recorded for a person with a normal movement pattern.

Figure 1 B is a frequency-resolved representation of a subset of time-resolved data recorded for a person with a normal movement pattern.

Figure 2A is a graphical representation of a subset of time-resolved data recorded for a person with an asymmetric movement pattern.

Figure 2B is a frequency-resolved representation of a subset of time-resolved data recorded for a person with an asymmetric movement pattern.

Figure 3 is a block scheme of a method for creating an index of an asymmetric movement pattern.

Figure 4 illustrates a system for creating an index of an asymmetric movement pattern. Figure 5A is an illustration of a person moving in a direction holding a handheld electronic device.

Figure 5B is an illustration of a person moving in a direction with a pocketed handheld electronic device.

Detailed description of the invention

The present inventive concept will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred variants of the inventive concept are shown. This inventive concept may, however, be implemented in many different forms and should not be construed as limited to the variants set forth herein; rather, these variants are provided for thoroughness and completeness, and to fully convey the scope of the inventive concept to the skilled person. Figure 5A is an illustration 500 of a person 502 moving in a direction 504 holding a handheld electronic device 520, and Fig. 5B is an illustration 600 of a person 602 moving in a direction 604 with a pocketed handheld electronic device 620. The handheld electronic device 520 in Fig. 5A and the pocketed handheld electronic device 620 in Fig. 5B are not necessarily separate devices, but may be two examples of placements of a single device. For instance, the handheld electronic device 520 may be placed in, e.g., a pocket. This is illustrated in Fig. 5B by a pocketed handheld electronic device 620. In the following, Fig. 5A and Fig. 5B will be described

simultaneously, except in relation to differences related to the position of the handheld electronic device 520 and the pocketed handheld electronic device 620. Hence, the pocketed handheld electronic device 620 may be referred to as the handheld electronic device 620 in the following.

An index of an asymmetric movement pattern of the person 502, 602 may be created from time-resolved data recorded by the handheld electronic device 520, 620. The handheld electronic device 520, 620 in the examples shown in Fig. 5A and Fig. 5B is a smartphone, but may, for instance, be a smartwatch. It is beneficial that the handheld user device 520, 620 is a device that the person 502, 602 normally carries, since it may reduce the need of awkward measuring equipment and may in turn increase the amount of collected time-resolved data. It may also reduce a number of visits to a specialized test center in case the person 502, 602 suffers from an asymmetric movement pattern. In other words, the handheld electronic device 520, 620 may simultaneously increase data related to the movement pattern of the person 502, 602 and reduce the complexity related to the measurement procedure.

The handheld electronic device 520, 620 shown in Fig. 5A and Fig. 5B is shown to comprise means 524, 624 for communications, however, the handheld electronic device 520, 620 comprise additional components, e.g. a processor, a data bus, a non- transitory computer-readable recording medium, an accelerometer, and a gyro. These additional components will be described in more detail in relation to Fig. 4. The means 524, 624 for communications are in the examples shown in Fig. 5A and Fig. 5B a cellular phone antenna capable of communicating via, e.g., 3G, 4G, and/or 5G. A skilled person realizes that there is a plurality of suitable means 524, 624 for communications, such as devices capable of communicating via cellular radio (e.g. 3G, 4G, 5G), Wi-Fi, Bluetooth, NFC, or any other dedicated protocol for wireless

communication.

The handheld electronic device 520, 620 is configured to establish a communication channel 530, 630 to a server, and to transmit time-resolved data via the communication channel 530, 630. The time-resolved data may be time-resolved acceleration data provided by the accelerometer of the handheld electronic device 520, 620 and time- resolved gyro data provided by the gyro of the handheld electronic device 520, 620. In other words, the time-resolved data may be related to the movement of the person 502, 602. The server is not shown in Fig. 5A or Fig. 5B, and it, together with its functions, will be described in more detail in relation to Fig. 4. The time-resolved data may pertain to normal movement of the person 502, 602. For example, normal movement may be that the person 502, 602 is walking normally. An example of time-resolved data pertaining to normal movement of a person is shown in, and will be described in relation to, Fig. 1 A. The time-resolved data may alternatively pertain to an asymmetric movement of the person 502, 602. For example, asymmetric movement may be that the person 502, 602 is limping. An example of time-resolved data pertaining to asymmetric movement of a person is shown in, and will be described in relation to,

Fig. 2A.

In the example shown in Fig. 5B, an orientation in space of the pocketed handheld electronic device 620 is tilted and may vary as the person 602 is moving. This may happen since the pocketed handheld electronic device 620 is positioned adjacent to a thigh of the person 602. In other words, a coordinate system of the pocketed handheld electronic device 620 is translated and rotated as the person 602 is moving. More specifically, a direction of a vertical axis 695 of the coordinate system of the pocketed handheld electronic device 620 is tilted, and may vary as the person 602 is moving, compared to a vertical axis 690 of a global coordinate system.

This may be compared to a coordinate system for the handheld electronic device 520, which, in the example shown in Fig. 5A, may only be translated in response to the movement of the person 502, given that the person 502 holds the handheld electronic device 520 such that it does not rotate. More specifically, a direction of a vertical axis 595 of the coordinate system of the handheld electronic device 520 may not vary as much as the direction of the vertical axis of the coordinate system of the pocketed electronic device. Since the direction of the vertical axis 695 of the coordinate system of the pocketed handheld electronic device 620 is varying, the coordinate system of the pocketed handheld electronic device 620 may be transformed such that the vertical axis 695 is oriented along the global vertical axis 690. In other words, the vertical axis 595, 695 of the coordinate system of the handheld electronic device 520, 620 may be transformed such that it aligns with the vertical axis 590, 690 of the global coordinate system. A transformation of the coordinate system may be performed at the server, and will be explained in greater detail in relation to Fig. 4.

It is to be understood that the specific example described above may be interchanged, such that the vertical axis 595 of the coordinate system of the handheld electronic device 520 is tilted and may vary, in relation to the global vertical axis 590, and that the vertical axis 695 of the coordinate system of the pocketed handheld electronic device 620 is not tiled, in relation to the global vertical axis 690. In other words, a skilled person realizes that the handheld electronic device 520 and the pocketed handheld electronic device 620 may be interchanged in the description above.

Figure 1 A is a graphical representation 101 of a subset 1 12 of time-resolved data 1 10 recorded for a person with a normal movement pattern. For example, the normal movement pattern may be a person walking. In the specific example shown in Fig. 1 A, the time-resolved data 1 10 is time-resolved acceleration data. The subset 1 12 of the time-resolved data 1 10 has a duration of 5 seconds. Alternatively, the subset 1 12 may have a duration in a range of 1 -10 seconds. Another alternative may be to use a plurality of subsets of different durations. In one embodiment the duration of a subset is based on previous analyses of asymmetric movement pattern.

As can be seen in Fig. 1A, there are a number of local extrema 1 16 relating to the movement pattern of the person. For the example shown in Fig. 1 A, ten local extrema 1 16 with amplitudes larger than a threshold value 1 14 may be identified. The local extrema 1 16 may be related to a number of steps taken by the person during the duration of the subset 1 12 of the time-resolved data 1 10. Markers representative of the asymmetric movement pattern may be based on the number of local extrema 1 16, which in the case shown in Fig. 1 A is ten for the duration of the subset 1 12. It is to be understood the markers above have been described in relation to local maxima as an example only, and that the markers may, alternatively or additionally, be based on local minima and/or a moment of the time-resolved data 1 10.

The local extrema 1 16 in Fig. 1A are separated by similar time differences, which in this specific case is about 0.5 seconds. This is one example of a feature that may relate to a movement pattern of low asymmetry.

Figure 1 B is a graphical representation 102 of a frequency-resolved representation 120 of a subset 122 of time-resolved data 1 10 recorded for a person with a normal movement pattern. In other words, Fig. 1 B is a graphical representation 102 of a frequency-resolved representation 120 of the time-resolved data 1 10 in Fig. 1 A. A marker related to the frequency-resolved representation 120 of the subset 122 of time- resolved data 1 10 may be based on relative amplitudes of frequencies present in the frequency-resolved representation 120 of the subset 122 of time-resolved data 1 10.

For instance, it may be possible to determine and compare amplitudes of a

fundamental frequency and related overtones in the frequency-resolved representation 120 of the subset 122 of time-resolved data 1 10. As a specific, non-limiting example, a marker may be based on a ratio of the amplitude of the fundamental frequency and the amplitude of the first overtone, and on a ratio of the amplitude of the second overtone and the amplitude of the third overtone. The marker related to the frequency-resolved representation 120 of the subset 122 of time-resolved data 1 10 may, additionally or alternatively, be based on a number of overtones. Preferably, only the overtones over a predefined frequency are taken into account. Dominating overtones above the predefined frequency are added up to a sum, which may serve as a reverse indication of asymmetry, such as limping (for limping subjects the overtones may generally have less energy than non-limping subjects). Moreover, in one embodiment of the presently disclosed method for analyzing an asymmetric movement pattern of a subject, the one or more features in the frequency-resolved representation (120, 220) of the time- resolved data (1 10, 210) comprise a quote of an amplitude of a first overtone for acceleration and/or gyro data and the sum of amplitudes of the remaining overtones. Figure 2A is a graphical representation 201 of a subset 212 of time-resolved data 210 recorded for a person with an asymmetric movement pattern. For example, the asymmetric movement pattern may be a person limping. In the specific example shown in Fig. 2A, the time-resolved data 210 is time-resolved acceleration data. The subset 212 of the time-resolved data 210 has a duration of 5 seconds. Alternatively, the subset 212 may have a duration in a range of 1 -10 seconds. Another alternative may be to use a plurality of subsets of different durations.

A number of local extrema 216 with amplitudes larger than a threshold value 214 similar to the threshold value 1 14 in Fig. 1 A, is seven for the example shown in Fig. 2A. The local extrema 216 in Fig. 2A is separated by a varying time difference, which is in a range of about 0.25-1.75 seconds. This is one example of a feature that may relate to a movement pattern of high asymmetry. This may be compared to Fig. 1 A, which shows a subset 1 12 of time-resolved data 1 10 related to a person with a normal movement pattern. In Fig. 1 A, the local extrema are separated by similar time differences of about 0.5 seconds. In other words, the movement pattern related to the subset 1 12 of time- resolved data 1 10 in Fig. 1 A is less asymmetric than the movement pattern related to the subset 212 of time-resolved data 210 in Fig. 2A. It is to be understood the markers above have been described in relation to local maxima as an example only, and that the markers may, alternatively or additionally, be based on local minima and/or a moment of the time-resolved data.

Figure 2B is a graphical representation 202 of a frequency-resolved representation 220 of a subset 222 of time-resolved data 210 recorded for a person with an asymmetric movement pattern. In other words, Fig. 2B is a graphical representation 202 of a frequency-resolved representation 220 of the time-resolved data 210 in Fig. 2A. It is to be understood that markers related to the frequency-resolved representation 220 of the subset 222 of time-resolved data 210 may be based on similar features as described in relation to Fig. 1 B.

Comparing the frequency-resolved representation 120 Fig. 1 B with the frequency- resolved representation 220 in Fig. 2B, it may be seen that a number of overtones in Fig. 1 B is higher than a number of overtones in Fig. 2B. This may be an indication of a lower asymmetry in the movement pattern related to Fig. 1 B compared to the movement pattern related to Fig. 2B.

Figure 3 is a block scheme of a method 300 for creating an index of an asymmetric movement pattern. The method 300 comprises the following acts:

Transforming 302 time-resolved data 1 10, 210 to a frequency-resolved representation 120, 220 of the time-resolved data 1 10, 210. The time-resolved data 1 10, 210 is related to an asymmetric movement pattern of a test subject. In this specific example, the frequency-resolved representation 120, 220 is a fast Fourier transform (FFT) of the time-resolved data 1 10, 210. A skilled person realizes that it there are other ways to transform 302 the time-resolved data 1 10, 210 to a frequency-resolved representation 120, 220 of the time-resolved data 1 10, 210. The time-resolved data 1 10, 210 in this case comprise time-resolved acceleration data, which relates to acceleration components of the asymmetric movement pattern. The time-resolved acceleration data may also be used to transform a coordinate system of the time-resolved data 1 10, 210. Alternatively, or additionally, the time-resolved data 1 10, 210 may comprise time- resolved gyro data relating to rotational components of the asymmetric movement pattern. The time-resolved gyro data may also be used to transform a coordinate system of the time-resolved data 1 10, 210. In this context, operations on the time- resolved data 1 10, 210 is described as being performed on the entire set of the time- resolved data 1 10, 210. However, an alternative is to perform operations on subsets 1 12, 212 of the time-resolved data 1 10, 210 and the frequency-resolved representation 120, 220 of the time-resolved data 1 10, 210. It is to be understood that different subsets may be used for different features. It is also to be understood that different subsets may be used for the time-resolved data 1 10, 210 and for the frequency- resolved representation 120, 220 of the time-resolved data 1 10, 210.

Prior to transforming 302 the time-resolved data 1 10, 210 to a frequency-resolved representation 120, 220 of the time-resolved data 1 10, 210, the time-resolved data 1 10, 210 may be filtered using a bandpass filter. This may be done, for example, in order to reduce noise present in the time-resolved data 1 10, 210. A measure of an energy of the filtered time-resolved data 1 10, 210 may also be determined.

Determining 304 one or more markers representative of the asymmetric movement pattern. The one or more markers are based on one or more features in the time- resolved data 1 10, 210 and on one or more features in the frequency-resolved representation 120, 220 of the time-resolved data 1 10, 210. Alternatively, the one or more markers may be based on either one or more features in the time-resolved data 1 10, 210 or one or more features in the frequency-resolved representation 120, 220 of the time-resolved data 1 10, 210.

For example, it is possible to determine dominant frequencies in the frequency- resolved representation 120, 220 of the time-resolved data 1 10, 210. The dominant frequencies are examples that may be used as features that the markers are based on. Examples of additional or other features in the time-resolved data 1 10, 210 or in the frequency-resolved representation 120, 220 of the time-resolved data 1 10, 210 that the markers may be based on are a number of local extrema, a ratio between amplitudes of local extrema, a moment of the time-resolved data 1 10, 210, a moment of the frequency-resolved representation 120, 220 of the time-resolved data 1 10, 210, and a linear combination of amplitudes of local extrema.

Creating 306 the index of the asymmetric movement pattern based on the one or more markers. The index created in this specific example is a weighted sum of the markers. Alternatively, other combinations of the markers may be a base used to create the index. The index may be created such that it is reproducible, for example by basing the index on at least two different markers. In other words, the index may be compared to other indices created at other occasions. This creates indices for different test subjects that may be compared.

The method may further comprise: checking 312 if a moment of the time-resolved data 1 10, 210 is above a predetermined threshold, and checking 314 if a dominant frequency of the frequency-resolved representation 120, 220 of the time-resolved data 1 10, 210 is above a predetermined frequency threshold. In other words, an amount of noise in the time-resolved data 1 10, 210 may be determined by checking 312 if the moment of the time-resolved data 1 10, 210 is above a predetermined threshold. By checking 314 if the dominant frequency of the frequency-resolved representation 120, 220 of the time-resolved data 1 10, 210 is above a predetermined frequency threshold, it may be possible to distinguish the movement the time-resolved data 1 10, 210 pertains to, for example, if the movement pertains to walking or a car ride.

The method 300 may further comprise filtering 308 the time-resolved data 1 10, 210 through a bandpass filter.

The method 300 may further comprise determining 310 a measure of an energy of the filtered time-resolved data 1 10, 210.

The method 300 may further comprise checking 312 if a moment of the time-resolved data 1 10, 210 is above a predetermined threshold. The method 300 may further comprise checking checking 314 if a dominant frequency of the frequency-resolved representation 120, 220 of the time-resolved data 1 10, 210 is above a predetermined frequency threshold.

Figure 4 illustrates a system 400 for creating an index of an asymmetric movement pattern. In Fig. 4, a server 410 comprising a processor 412 is shown. In the example shown in Fig. 4, the server 410 further comprises means 414 for communications and a data bus 415. The processor 412 and the means 414 for communications are connected by the data bus 415. The server 410 in this specific example is a stationary server. Alternatively, the server may be mobile. The means 414 for communications in the example shown in Fig. 4 is Wi-Fi. Alternatively, the means 414 for communications may be wired Ethernet, USB, cellular radio. A skilled person realizes that there is a plurality of suitable means 414 for communications, such as devices capable of communicating via cellular radio (e.g. 3G, 4G, 5G), Wi-Fi, Bluetooth, NFC, or any other dedicated protocol for wireless communication.

The system 400 shown in Fig. 4 further comprises a handheld electronic device 420. In the example shown in Fig. 4, the handheld electronic device 420 is a smartphone. Alternatively, the handheld electronic device 420 may be a smartwatch or another kind of wearable handheld electronic device. In case the handheld electronic device 420 is a device that the user normally carries, the time-resolved data 1 10, 210 may be gathered over an extended period of time.

The handheld electronic device 420 comprises processing capabilities in the form of a processor 422, means 424 for communications, a data bus 425, a non-transitory computer-readable recording medium 426, an accelerometer 428, and a gyro 429. In this case, the time-resolved data 1 10, 210 comprises time-resolved acceleration data. Alternatively, or additionally, the time-resolved data 1 10,120 may further comprise time-resolved gyro data. In the example shown in Fig. 4, the time-resolved acceleration data is provided by the accelerometer 428. The time-resolved gyro data may be provided by the gyro 429. The processor 422, means 424 for communications, the non- transitory computer-readable recording medium 426, the accelerometer 428, and the gyro 429 in Fig. 4 are configured to communicate with each other via the data bus 425.

The handheld electronic device 420 in Fig. 4 has means 424 for communications in the form of a cellular radio, capable of receiving and transmitting the time-resolved data 1 10, 210. Other means 414 of communications may be Wi-Fi, Bluetooth, NFC, or a dedicated protocol for wireless communication. In case the server 410 is a mobile server or if the handheld electronic device 420 is in the vicinity of the server 410, wired communication, such as Ethernet or USB, may be used between the server 410 and the handheld electronic device 420.

The non-transitory computer-readable recording medium 426 has recorded thereon a program which is executable on the handheld electronic device 420. The program may be an application downloadable to the handheld electronic device 420 via an application providing service. The program comprises program code portions which when executed on the handheld electronic device 420 is configured to establish a communication channel 430 between the handheld electronic device 420 on which the program is executed and the server 410. The communications channel 430 in Fig. 4 is establish using the means 414, 424 for communications of the server 412 and the handheld electronic device 420.

The program comprises program code portions which when executed on the handheld electronic device 420 is further configured to evaluate acceleration data from the accelerometer 428 of the handheld electronic device 420 to determine if a user of the handheld electronic device 420 is moving. As long as it is determined that the user is moving, the program code portions are further configured to transmit, via the communication channel 430, time-resolved data 1 10, 210 from the handheld electronic device 420. In other words, the time-resolved data 1 10, 210 is transmitted to the server 410 as long as the program code portions determines that the user of the handheld electronic device 420 is moving. This configuration may result in a reduced energy consumption of the handheld electronic device 420, as the time-resolved data 1 10, 210 is not transmitted in case the user is not moving. For example, the program may comprise program code portions which when executed on the handheld electronic device 420 is further configured to evaluate if the user of the handheld electronic device 420 is moving by, for a predetermined time period of the time-resolved acceleration data: check if a moment of the time-resolved data 1 10, 210 is above a predetermined threshold. In the example shown in Fig. 4, the predetermined time period is 5 seconds, but may alternatively be in a range of 1 -10 seconds.

The processor 412 of the server 410 is configured to transform the time-resolved data 1 10, 210 to a frequency-resolved representation 120, 220 of the time-resolved data 1 10, 210. In the example shown in Fig. 4, the processor 412 is configured to transform the time-resolved data 1 10, 210 using a fast Fourier transform (FFT).

The processor 412 may further be configured to filter the time-resolved data 1 10, 210 using a bandpass filter in order to reduce noise, and to determine a measure of an energy of the filtered time-resolved data. In case the time-resolved data 1 10, 210 is to be filtered, it is preferably filtered prior to the transform of the time-resolved data 1 10, 210 to a frequency-resolved representation 120, 220 of the time-resolved data 1 10, 210.

The processor 412 is further configured to determine one or more markers

representative of an asymmetric movement pattern for the user of the handheld electronic device 410. The one or more markers are based on one or more features chosen from the group of features consisting of: a number of local extrema in the time- resolved data 1 10, 210, a moment of the time-resolved data 1 10, 210, a number of local extrema in the frequency-resolved representation 120, 220 of the time-resolved data 1 10, 210, a ratio between amplitudes of local extrema in the frequency-resolved representation 120, 220 of the time-resolved data 1 10,210, a moment of the frequency- resolved representation 120, 220 of the time-resolved data 1 10, 210, and a linear combination of amplitudes of local extrema in the frequency-resolved representation 120, 220 of the time-resolved data 1 10, 210.

The processor is further configured to create an index of the asymmetric movement pattern based on the one or more markers.

The person skilled in the art realizes that the present inventive concept by no means is limited to the preferred variants described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. Additionally, variations to the disclosed variants can be understood and effected by the skilled person in practicing the claimed inventive concept, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word“comprising” does not exclude other elements or steps, and the indefinite article“a” or“an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage. Further details of the invention

1. A method for creating an index of an asymmetric movement pattern, the

method (300) comprising:

- transforming (302) time-resolved data (1 10, 210) to a frequency-resolved representation (120, 220) of the time-resolved data (1 10, 210), determining (304) one or more markers representative of the asymmetric movement pattern, wherein the one or more markers are based on one or more features in the time-resolved data (1 10, 210) and/or on one or more features in the frequency-resolved representation (120, 220) of the time- resolved data (1 10, 210), and

- creating (306) the index of the asymmetric movement pattern based on the one or more markers.

2. The method (300) according to item 1 , wherein the time-resolved data (1 10, 210) comprises time-resolved acceleration data.

3. The method (300) according to item 2, wherein the time-resolved data (1 10, 210) further comprises time-resolved gyro data.

4. The method (300) according to any one of items 1 -3, wherein the one or more features in the time-resolved data (1 10, 210) comprise:

- a number of local extrema in the time-resolved data (1 10, 210), and

- a moment of the time-resolved data (1 10, 210),

and wherein the one or more features in the frequency-resolved representation (120, 220) of the time-resolved data (1 10, 210) comprise:

- a number of local extrema in the frequency-resolved representation (120, 220) of the time-resolved data (1 10, 210),

- a ratio between amplitudes of local extrema in the frequency-resolved representation (120, 220) of the time-resolved data (1 10, 210), - a moment of the frequency-resolved representation (120, 220) of the time- resolved data (1 10, 210), and

- a linear combination of amplitudes of local extrema in the frequency- resolved representation (120, 220) of the time-resolved data (1 10, 210). The method (300) according to item 1 -4, wherein the one or more features in the time-resolved data (1 10, 210) are one or more features in one or more subsets (1 12, 212) of the time-resolved data (1 10, 210), and wherein the one or more features in the frequency-resolved representation (120, 220) of the time- resolved data (1 10, 210) are one or more features in one or more subsets (122,

222) of the frequency-resolved representation (120, 220) of the time-resolved data (1 10, 210). The method (300) according to any one of items 1 -5, wherein the one or more markers are at least two different markers. The method (300) according to any one of items 1 -6, the method (300) further comprising:

- filtering (308) the time-resolved data (1 10, 210) through a bandpass filter, and

- determining (310) a measure of an energy of the filtered time-resolved data

(1 10, 210).

The method (300) according to any one of items 1 -7, the method (300) further comprising:

- checking (312) if a moment of the time-resolved data (1 10, 210) is above a predetermined threshold, and

- checking (314) if a dominant frequency of the frequency-resolved

representation (120, 220) of the time-resolved data (1 10, 210) is above a predetermined frequency threshold.

A system comprising:

- a server (410) comprising a processor (412),

- a non-transitory computer-readable recording medium (426) having

recorded thereon a program which is executable on a handheld electronic device (420) having processing capabilities (422), wherein the program comprises program code portions which when executed on the handheld electronic device (420) is configured to:

o establish a communication channel (430) between the handheld electronic device (420) on which the program is executed and the server (410), o evaluate acceleration data from an accelerometer (428) of the handheld electronic device (420) to determine if a user of the handheld electronic device (420) is moving,

o as long as it is determined that the user is moving, transmit, via the communication channel (430), time-resolved data (1 10, 210) from the handheld electronic device (420),

wherein the processor (412) of the server (410) is configured to:

transform the time-resolved data (1 10, 210) to a frequency-resolved representation (120, 220) of the time-resolved data (1 10, 210),

determine one or more markers representative of an asymmetric movement pattern for the user of the handheld electronic device (420), wherein the one or more markers are based on one or more features chosen from the group of features consisting of:

o a number of local extrema in the time-resolved data (1 10, 210), o a moment of the time-resolved data (1 10, 210),

o a number of local extrema in the frequency-resolved representation (120, 220) of the time-resolved data (1 10, 210),

o a ratio between amplitudes of local extrema in the frequency- resolved representation (120, 220) of the time-resolved data (1 10, 210),

o a moment of the frequency-resolved representation (120, 220) of the time-resolved data (1 10, 210), and

o a linear combination of amplitudes of local extrema in the frequency- resolved representation (120, 220) of the time-resolved data (1 10, 210), and

create an index of the asymmetric movement pattern based on the one or more markers.

10. The system (400) according to item 9, wherein the time-resolved data (1 10, 210) comprises time-resolved acceleration data.

1 1. The system (400) according to item 9 or 10, wherein the time-resolved data (1 10, 210) comprises time-resolved gyro data. 12. The system (400) according to any one of items 9-1 1 , wherein the processor

(412) of the server (410) is further configured to: - filter the time-resolved data (1 10, 210) from the handheld electronic device (420) through a bandpass filter, and

- determine a measure of an energy of the filtered time-resolved data. 13. The system (400) according to any one of items 10-12, wherein the program comprises program code portions which when executed on the handheld electronic device (420) is further configured to evaluate if a user of the handheld electronic device (420) is moving by, for a predetermined time period of the time-resolved acceleration data:

- check if a moment of the time-resolved data (1 10, 210) is above a

predetermined threshold.

14. The system (400) according to item 13, wherein the predetermined time period of the time-resolved acceleration data is in the range of 1 -10 seconds, preferably 5 seconds.

15. The system (400) according to any one of items 9 to 14, wherein the handheld electronic device (420) is a smart wearable electronic device, such as a smartphone or a smartwatch.

16. The system (400) according to item 15, wherein the program is an application downloadable to the smartphone via an application providing service.

Claims

1. A method for analyzing an asymmetric movement pattern of a subject, such as a person or an animal, the method (300) comprising:

- transforming (302) the time-resolved data (1 10, 210) to a frequency- resolved representation (120, 220) of the time-resolved data (1 10, 210), determining (304) one or more markers representative of the asymmetric movement pattern, wherein the one or more markers are based on one or more features in the time-resolved data (1 10, 210) and/or on one or more features in the frequency-resolved representation (120, 220) of the time- resolved data (1 10, 210), and

- creating (306) an index representing a degree of asymmetry of the

asymmetric movement pattern based on the one or more markers.

2. The method (300) according to claim 1 , wherein the time-resolved data (1 10, 210) comprises time-resolved acceleration data, preferably time-resolved acceleration data obtained from a device, such as a handheld electronic device.

3. The method (300) according to claim 2, wherein the time-resolved data (1 10, 210) further comprises time-resolved gyro data, preferably time-resolved gyro data obtained from said device.

4. The method (300) according to any one of claims 1 -3, wherein the method is a method for analyzing gait and wherein the asymmetric movement pattern is a movement pattern for gait.

5. The method (300) according to any one of claims 1 -4, wherein the one or more features in the time-resolved data (1 10, 210) comprise:

- a number of local extrema in the time-resolved data (1 10, 210), and

- a moment of the time-resolved data (1 10, 210),

- a number of local extrema in the frequency-resolved representation (120,

220) of the time-resolved data (1 10, 210), - a ratio between amplitudes of local extrema in the frequency-resolved representation (120, 220) of the time-resolved data (1 10, 210),

- a moment of the frequency-resolved representation (120, 220) of the time- resolved data (1 10, 210), and

- a linear combination of amplitudes of local extrema in the frequency- resolved representation (120, 220) of the time-resolved data (1 10, 210).

6. The method (300) according to claim 1 -5, wherein the one or more features in the time-resolved data (1 10, 210) are one or more features in one or more subsets (1 12, 212) of the time-resolved data (1 10, 210), and wherein the one or more features in the frequency-resolved representation (120, 220) of the time- resolved data (1 10, 210) are one or more features in one or more subsets (122, 222) of the frequency-resolved representation (120, 220) of the time-resolved data (1 10, 210).

7. The method (300) according to any one of claims 1 -6, wherein the one or more markers are at least two different markers.

The method (300) according to any one of claims 1 -7, wherein each marker constitutes a dimension in a multidimensional space, and wherein the markers are translated to a combined marker representative of the asymmetric movement pattern by projecting the markers from the multidimensional space to a one-dimensional representation.

9. The method (300) according to any one of claims 1 -8, wherein an asymmetry reference level is represented by two clusters of training data projected from the multidimensional space to the one-dimensional representation, wherein the asymmetry reference level is a level between two clusters of training data in the one-dimensional representation.

10. The method (300) according to claim 9, wherein one of the two clusters is

representative of reference symmetric movement of the subject, and the other of the two clusters is representative of reference asymmetric movement of the subject.

1 1. The method (300) according to any one of claims 9-10, wherein the asymmetry reference level is selected as a level having equal distance to the two clusters of training data.

12. The method (300) according to any one of claims 9-1 1 , wherein the index is calculated as a distance between the reference level and the combined marker.

13. The method (300) according to any one of claims 9-12, wherein the one or more features in the time-resolved data (1 10, 210) and/or frequency-resolved representation (120, 220) of the time-resolved data (1 10, 210) further comprises a correlation of the acceleration data and/or gyro data.

14. The method according to any one of claims 1 -13, wherein acceleration data from the accelerometer (428) is evaluated to determine at least one interval of the time-resolved data (1 10, 210) that corresponds to gait of the subject, and using the time-resolved-data (1 10, 210) of the interval in the step of determining (304) the one or more markers representative of the asymmetric movement pattern.

15. The method (300) according to any one of claims 1 -14, the method (300) further comprising:

- determining (310) a measure of an energy of the filtered time-resolved data

(1 10, 210).

16. The method (300) according to any one of claims 1 -15, the method (300) further comprising:

- checking (314) if a dominant frequency of the frequency-resolved

17. A movement analysis system for analysis of an asymmetric movement pattern of a subject, comprising: a processor (412) configured to:

obtain time-resolved data (1 10, 210) representing the movement of said subject,

18. The system (400) according to claim 17, further comprising:

- a non-transitory computer-readable recording medium (426) having

o establish a communication channel (430) between the handheld electronic device (420) on which the program is executed and the processor (412),

o evaluate acceleration data from an accelerometer (428) of the handheld electronic device (420) to determine if a user of the handheld electronic device (420) is moving, o as long as it is determined that the user is moving, transmit, via the communication channel (430), time-resolved data (1 10, 210) from the handheld electronic device (420).

19. The system (400) according to any one of claims 17-18, wherein the time- resolved data (1 10, 210) comprises time-resolved acceleration data.

20. The system (400) according to any one of claims 17-19, wherein the time- resolved data (1 10, 210) comprises time-resolved gyro data.

21. The system (400) according to any one of claims 17-20, wherein the processor (412) of the server (410) is further configured to:

- filter the time-resolved data (1 10, 210) from the handheld electronic device (420) through a bandpass filter, and

- determine a measure of an energy of the filtered time-resolved data.

22. The system (400) according to any one of claims 17-21 , wherein the program comprises program code portions which when executed on the handheld electronic device (420) is further configured to evaluate if a user of the handheld electronic device (420) is moving by, for a predetermined time period of the time-resolved acceleration data:

- check if a moment of the time-resolved data (1 10, 210) is above a

predetermined threshold.

23. The system (400) according to claim 22, wherein the predetermined time period of the time-resolved acceleration data is in the range of 1 -10 seconds, preferably 5 seconds.

24. The system (400) according to any one of claims 17-23, wherein the handheld electronic device (420) is a smart wearable electronic device, such as a smartphone or a smartwatch.

25. The system (400) according to claim 24, wherein the program is an application downloadable to the smartphone via an application providing service.

26. The system (400) according to any one of claims 17-25, further comprising an accelerometer and/or a gyroscope for providing the time-resolved acceleration data and/or time-resolved gyro data.