WO2001050958A1

WO2001050958A1 - Method and system for analyzing a movement

Info

Publication number: WO2001050958A1
Application number: PCT/FI2000/000014
Authority: WO
Inventors: Simo Taimela
Original assignee: Dbc International Oy
Priority date: 2000-01-10
Filing date: 2000-01-10
Publication date: 2001-07-19
Also published as: AU2113400A

Abstract

The invention relates to a method and a system for analyzing a movement performed with a muscular exercise apparatus (1). From the measured velocity quantity, a statistical model describing its smoothness is generated; the statistical model is compared with predetermined models; and, based on the comparison, feedback regarding the quality of the movement is given. The system comprises means (7) for generating from the measured velocity quantity a statistical model describing the smoothness of the velocity quantity; means (8) for comparing the statistical model with predetermined models; and means (9) for giving feedback based on the comparison, regarding the quality of the movement.

Description

METHOD AND SYSTEM FOR ANALYZING A MOVEMENT

The present invention relates to a method as defined in the preamble of claim 1 and to a system as defined in the preamble of claim 5 for the analysis of a movement made with a muscle exercise apparatus.

Specification US 4,893,808 presents a device for the measurement of functional properties of the cervical spine or neck. According to the specification, the apparatus can be used to measure and analyze e.g. the velocity of movement and its changes in order to analyze deficiencies in the performance of the neck, but the specification does not disclose any concrete means or method for analyzing the measured information. A feature typical of musculoskeletal disorders is abnormal, e.g. jerky movement. The human mo- toric regulation system is disturbed e.g. in consequence of pain. From a medical point of view, research on this phenomenon is important ^for diagnosing. The problem is that current research methods are largely based on the observer's own experience, his/her opinion of correct and incorrect movement . An examination made by a rough estimation cannot be considered commensurate with other observers. Moreover, the instru- ments, such as a goniometer, used in the examination are very sensitive in respect of correctness of the method of measurement and calibration. Previously known is a system in which a movement is examined e.g. by means of a video system. In this case, special points whose movement is monitored via a digitized image recognition system are attached to the person testing the apparatus. The problems with this type of investigation are a complexity of the resources required by the system and the number of degrees of freedom; the essential features of the movement are difficult to distinguish from two-dimensional measurement data. The object of the invention is to eliminate the problems referred to above. A specific object of the invention is to disclose a new type of method and system that will make it possible to analyze the qual- ity of a movement performed with a muscular exercise apparatus .

The method of the invention is characterized by what is presented in claim 1. The system of the invention characterized by what is presented in claim 5. In the method of the invention, the velocity quantity of a movement is measured by means of a device connected to a part of a muscular exercise apparatus resisting the movement. A part resisting the movement means a part of the muscular exercise appara- tus which is moved by the user performing an exercise.

According to the invention, from the measured velocity quantity, a statistical model describing its smoothness is generated; the statistical model is compared with predetermined models; and, based on the comparison, feedback regarding the quality of the movement is given.

Based on measurement data obtained from tests with a larger number of persons, different models have been generated, on the basis of which the movement can be classified as a correct or an incorrect type of performance. Thus, it is possible e.g. to qualify the level of the movement performed with the muscular exercise apparatus. The user of the muscular exercise apparatus is given feedback about the quality of the performance. The feedback may be e.g. of a visual or auditory nature, and it is given e.g. during the performance, thus allowing the user to observe the quality of his/her own performance.

In a preferred embodiment, the statistical model is generated by dividing the path of the movement of the muscular exercise apparatus into sections and saving information regarding the time spent in 8

different sections. In this way, a statistical element representing the time spent in a section of the path of movement is generated. In addition, the direction of motion in the section of the path can be indicated with a sign digit.

The device measuring the movement is preferably connected to a rotatable main shaft of the muscular exercise apparatus. In an embodiment, the muscular exercise apparatus is an apparatus for the exercise of the cervical and upper spinal muscles. Thus, the statistical model can be generated by only considering the effect of appropriate groups of muscles.

Moreover, the invention relates to a system for the analysis of a movement performed with a muscu- lar exercise apparatus. According to the invention, the system comprises means for generating from a measured velocity quantity a statistical model describing the smoothness of the velocity quantity; means for comparing the statistical model with predetermined models; and means for giving feedback based on the comparison regarding the quality of the movement.

The system preferably comprises means for giving visual and/or auditory feedback to the user of the muscular exercise apparatus . The feedback may be given e.g. via a display device, a light system or equivalent, allowing the user to see the appraisal generated by the system regarding the level of the performance or movement. The feedback may also consist of a sound signal, a summer, speech synthesizer or equivalent.

In an embodiment of the invention, the system comprises means for dividing the path of motion of the muscular exercise apparatus into sections and means for storing information regarding the time spent in different sections of the path. From the statistical elements thus obtained, a statistical model is generated. In an embodiment, the device measuring the movement is connected to a rotating main shaft of the muscular exercise apparatus. The muscular exercise apparatus is preferably an apparatus for the exercise of the cervical and/or upper spinal muscles. In an embodiment, the means used to divide the path of movement into sections is a pulse detector. In an embodiment, the means for generating a statistical model and the means for performing a comparison are fitted in a computer system.

The advantages of the invention include simplicity of the measuring system; simple and cheap technical implementation requiring few components. In addition, the system of the invention can be easily connected to existing muscular exercise apparatus without any major changes. The invention also makes it possible to obtain immediate feedback regarding the level of the performance, so that the person doing the exercise can either interrupt the performance or change the parameters so as to make them more appropriate for him/herself. In addition, possible problems associated with the locomotor system can be detected. By means of the invention, the average velocity and accuracy of a movement within a limited extent of mo- tion and with a limited load is analyzed. The time derivatives thus obtained are analyzed by statistical means .

In the following, the invention will be described by the aid of a few examples of its embodi- ments with reference to the attached drawing, wherein

Fig. 1 presents a diagram representing a system according to the invention;

Fig. 2a and 2b present examples of muscular exercise apparatus to which the invention can be ap- plied; and

Fig. 3a and 3b present examples of statistical models according to the invention. The diagram in Fig. 1 represents a system according to the invention. The system is connected to a muscular exercise apparatus 1. The muscular exercise apparatus 1 comprises a part resisting the movement. A part resisting the movement means a part which moves in the muscular exercise apparatus 1 while the user is performing an exercise with the apparatus . The exercise can also be performed with zero resistance or with a minimal resistance, in which case the function of the muscular exercise apparatus 1 is not to create a strain but primarily to guide the user towards performing a movement correctly in respect of its path. The system comprises means 6 for measuring the smoothness of a velocity quantity. The means 6 are connected to the part of the muscular exercise apparatus 1 which resists the movement, e.g. to a rotating main shaf . The velocity quantity of the movement, the smoothness of which is measured, is e.g. the velocity of the movement, in which case the smoothness measurement is obtained as an acceleration value. In other words, the acceleration values are obtained as derivatives of velocity. Using means 6, the path of movement of the muscular exercise apparatus 1 can be divided into sections, thus permitting a sample to be obtained from each section of the path with respect to time. The path is divided into sections by means of a pulse detector attached to the main shaft . The output of the pulse detector consists of two rectangular wave signals, and the direction of rotation can be deduced from the phase difference between the signals.

The samples obtained from the path of movement of the muscular exercise apparatus are stored using means 10, and a statistical model can be generated using means 7. Using means 8, the statistical model thus generated is compared with predetermined statistical models. The predetermined statistical models have been generated on the basis of a large random sample of patients, thus creating different classes; for example, the magnitude of a functional disorder of the cervical spine can be defined by the aid of the classification. Based on the comparison, using means 9, feedback is given to the person doing the exercise or to a person making a diagnosis . The feedback may consist of e.g. three different light signals implemented using LED ' s corresponding to the level of the performance according to the classification.

The system of the invention is partly implemented using a computer system 11. The output of a pulse detector 6 is connected to the computer system 11 e.g. via a parallel port of the computer. The com- puter converts the rectangular wave into a pulse defined with respect to time, collects the pulses into a file and generates a statistical model on the basis of the file. The comparison with a predetermined statistical model and the feedback given on the basis of the comparison can also be implemented using a computer.

Fig. 2a and 2b present examples of muscular exercise apparatus in which the system of the invention can be incorporated. Fig. 2a shows an apparatus, presented in Finnish patent application FI-980039, for the exercise and rehabilitation of the motional pattern of the cervical spine and/or the muscles around the cervical spine via a rotational exercise movement of the head. The apparatus can be used to perform rotational exercise movements of the cervical spine in order to learn a correct three-dimensional motional pattern of the rotation of the cervical spine. By attaching a pulse detector to the main shaft 12, it is possible to distinguish from the three-dimensional motion a movement rotating in one plane only, thus pro- ducing a pulse detector output describing the function of a more precisely defined group of muscles. Another example of the placement of the pulse detector is the main shaft 12 of the muscular exercise apparatus as shown in Fig. 2b. Fig. 2b presents an apparatus described in Finnish patent application FI-974645, which can be used to exercise and rehabilitate neck exten- sors by a flexion and extension movement of the neck.

Fig. 3a and 3b present examples of statistical models according to the invention, representing neck movements in the muscular exercise apparatus. In both figures, the x-axis describes the pulse duration while the y-axis represents the number of pulses, in other words, the figures present a histogram divided according to the pulse duration.

Fig. 3a shows a histogram with two sharp peaks, from which it can be seen that the movement has been smooth in both directions. A smooth movement produces pulses of even length. Such a movement is normal neck movement. Fig. 3b represents a jerky movement of a neck suffering from disorders. It can be seen from the figure that the duration of the pulses is more evenly distributed, even into several peaks of different lengths. By forming classes from the reference material thus obtained, the performance of the user of the muscular exercise apparatus can be compared with a larger user group. The quantities that may be used for the comparison include zero point symmetry, peak sharpness, distribution width and absolute location of the peak. If there occurs a jerk in the other direction, then the histogram will show a dual -peak distribution. The invention is not restricted to the examples of its embodiments described above, but many variations are possible within the scope of the inventive idea defined in the claims.

Claims

1. Method for analyzing a movement performed with a muscular exercise apparatus (1) , in which method the velocity quantity of the movement is meas- ured by means of a device (6) connected to a part of the muscular exercise apparatus resisting the movement , charact eri zed in that from the measured velocity quantity, a statistical model describing its smoothness is generated; - the statistical model is compared with predetermined models; and

- based on the comparison, feedback regarding the quality of the movement is given.

2. Method as defined in claim 1, cha - acteri zed in that the statistical model is generated by dividing the path of the movement of the muscular exercise apparatus (1) into sections and storing information regarding the time spent in different sections.

3. Method as defined in claim 1 or 2, characteri zed in that the device (6) measuring the measurement is connected to a rotatable main shaft (12) of the muscular exercise apparatus (1) .

4. Method as defined in any one of claims 1 - 3, charact eri zed in that the muscular exercise apparatus is an apparatus for the exercise of the cervical and/or upper spinal muscles .

5. System for the analysis of a movement performed with a muscular exercise apparatus (1) , said system comprising means (6) for measuring the velocity quantity of the movement by means of a device connected to a part of the muscular exercise apparatus resisting the movement, charac t eri zed in that the system comprises - means (7) for generating from the measured velocity quantity a statistical model describing the smoothness of the velocity quantity; - means (8) for comparing the statistical model with predetermined models; and means (9) for giving feedback based on the comparison, regarding the quality of the movement.

6. System as defined in claim 5, char act eri zed in that the system comprises means (6) for dividing the path of movement of the muscular exercise into sections and means (10) for storing information regarding the time spent in different sec- tions, thus generating a statistical model from the velocity quantity.

7. System as defined in claim 5 or 6, characteri zed in that the device (6) measuring the movement is connected to a rotatable main shaft (12) of the muscular exercise apparatus (1) .

8. System as defined in any one of claims 5 -

7, charact eri zed in that the muscular exercise apparatus is an apparatus for the exercise of the cervical and/or upper spinal muscles .

9. System as defined in any one of claims 5 -

8, characteri z ed in that the means (6) dividing the path of movement into sections is a pulse detector.

10. System as defined in any one of claims 5 - 9 , c h a r a c t e r i z e d in that the means for generating a statistical model and the means (8) for performing a comparison have been fitted in a computer system (11) .