D.Yu. Balanev, associate professor, Ph.D.
L.V. Kapilevich, professor, Dr.Med.
V.G. Shil'ko, professor, Dr.Hab.
National Research Tomsk State University, Tomsk

Keywords: dynamics of development, motor activity, techniques, monitoring.

Introduction. Owing to the rapid development of measuring techniques of the characteristics of human motor activity researchers, physiologists, psychologists, health professionals in the field of sport, can solve the problem of formation of motor skills in a new way. It becomes possible to organize continuous monitoring of athlete's motor activity during any period of his life, as well as design well-controlled learning environments meant for work on individual motor acts and the system of motor activity in general. The dynamics of development of such systems can be seen not only in scientific publications and patents for inventions and utility models, representing the state of the market solutions for practical use.

Evaluation of human motor activity is among the major subjects of theoretical and practical activities aimed at improvement of sports achievements. Depending on the goals and opportunities, such an evaluation can be based on subjective and objective, direct and indirect criteria, be carried out using the method of observation and instrumental measurements, is performed by an athlete and his trainer, includes some elements of the training process and involves all spheres of life. When the process is organized, carried out on a regular basis and is a source of reflection for an athlete and his trainer, we qualify it as monitoring of motor activity. However, researchers believe, one more condition should be implemented: monitoring is to be a source of generalizations that can be evaluated using the criteria of scientific novelty. In this case, the knowledge gained will probably be converted into new technologies that can ensure an increase in quality, reliability, staginess of sports achievements and prevent injuries.

The required level of scientific novelty is provided via choosing an adequate measuring system and methods of mathematical processing of measurement results. As we believe, it is most promising in this respect to use an array of patent information not only on the current state of the market of measuring systems, but also on its development trends. Moreover, if knowing such a trend in-house developments can be presented in this market, indicating the high practical importance of research aimed at improving of motor skills in sport.

As seen from analysis of the development trends of the motor activity monitoring systems, the most common and promising technologies are those that can generally be described as "motion capture systems”. We distinguish them from the systems aimed at traditional sports use of indirect measures of motor activity including: heart rate, breathing characteristics, frequency and speed indices of cyclic exercises, fixing of visually observed movement features [2]. Motion capture systems ensure measurement of processual characteristics of motor activity, related to the values of displacements, velocity, acceleration, and rotation angle of particular points on the athlete’s body. There are many of such systems, differing in action: mechanical, optical, electromagnetic, inertial, acoustic and radio frequency. In our research, we use the most common optical system based on the Phantom Miro Ex2 digital high-speed imaging camera (Vision Research Inc. (USA), the FASTRAK electromagnetic system (Polhemus Inc. (USA), and the self-design inertial system based on the MPU-6000 integrated microelectromechanical device comprising a 3-axis gyroscope and a 3-axis accelerometer (InvenSense Inc. (USA). The Xsens MVN solution of Xsens Technologies BV (Netherlands) can be taken as the closest analogue. Among the criteria of choosing this equipment was the available patent on the technologies applied in it [3-5]. This approach provides a more adequate assessment of the hardware capabilities, the necessary level of innovation, forms the technology benchmark and the prototype that can be used as a basis for unconventional solutions.

The reason why it is impossible to use any single technology for all forms of monitoring of motor activity is that each of them has its pros and cons. The optical motion capture system is good due to its high speed capability. The video camera we use records with an accuracy of 5 ms. Another advantage is the possibility to assess a sufficiently large number of key points up to a few dozen. The disadvantages are its high cost, high computing requirements for data processing and workspace limitations.

An electromagnetic tracking system provides acceptable operation speed (120 frames per second) but only in the case of one key point. All in all, up to four points with a proportional reduction in the resolution can be tracked simultaneously. Electromagnetic system is costly and imposes significant constraints on the workspace. These constraints are different from those characteristic of optical systems and can partially make up for them. However, this system provides data on six degrees of freedom of motion of the key point without using additional computing power, which is its biggest advantage over other solutions.

The measuring system is based on inertial sensors, has a high potential as a mobile solution, does not limit the workspace, is zoomed well to tens of key points, provides a minimal resolution level (100-200 frames per second). But the solution based on the microelectromechanical triaxial accelerometer requires for calculation motion data, a double integration operation, which significantly reduces the measurement accuracy. However, in most cases, motor activity can be estimated only on the basis of accelerograms.

Despite their novelty, acoustic and radar technologies of the motion capture system are not common in the solutions available in the market and can be promising [6, 1].

It should be noted that speaking about motor activity monitoring systems, we mean not only the measurement of the parameters of this activity, but also the equipment and methods that ensure the conditions of motor skill formation along with simultaneous recording of results and parameters. As an example, below is a description of three devices involving human motor activity monitoring devices for the purpose of formation of motor skills. Analysis of the patents’ descriptions given for these devices shows their basic features in view of the twenty years long patent search depth. We used these devices as a basis to develop our own solution, issued in the form of a utility model patent designed to develop motor skills, inclusive of sports application [7].

The system of training a person to move along a path in a virtual environment [8] was proposed in 1994 by employees of Massachusetts Institute of Technology. This system represents a device and a method for learning motor skills, based on the “student” simulating his "teacher’s" motion. The electromagnetic motion capture system is suggested by the authors for motion detection with the sensor fixed to the surface of the sports equipment. Racket is specified in the claim as an object which defines the nature of the "student’s" motion, and a ball model interacting with the racket is introduced in the three-dimensional interactive virtual environment. Thus, the racket’s motion in the digital form is saved in the non-volatile computer memory, and the video sequence representing the "teacher’s" motion reconstruction is displayed on a computer screen. Then the device used to record the "teacher’s" motion fixes the "student’s" motions, which are also displayed on the screen in another video sequence, superimposed onto the image of the "teacher’s" motions. This process is repeated until the teacher and the student’s motions match in the temporal and spatial characteristics. The specific features of the invention include the ability to control the time scale during which the "teacher’s" motion is displayed on the screen and the ability to estimate the "student’s" performance based on his actions – hitting the target with a virtual ball.

The system and method of training and evaluation of human motion proposed in 2004 by C. Choquet [9] can be used to train athletes using special physical exercises and estimate their actions in an organized workspace. The training environment is made of the space set with special reference points, within which objects, imitating objects that interact with an athlete can move freely. The learning environment is set by means of computer. Changes in the spatial position of objects are controlled using special detectors. The effects caused by the actions of the user who performs the operating control are displayed via a three-dimensional modeling system. The user can see the data of the three-dimensional modeling on the screen in real time. The user's action data and the effect from them are saved and used for assessment of his skills.

The “Virtual trainer" system and method, reported in 2007 by the employees of Health Hero Network, Inc. (USA) [10] is described by the authors as a human health managing tool. Motor activity is measured only in quantitative terms - taking into account the frequency of movements when doing a repetitive exercise. The user performs a pre-programmed physical exercise. The major parameters specific for this exercise like body temperature, heart rate, blood pressure are measured using a set of sensors. The frequency of movements, typical for this exercise, is also measured using a motion sensor. The findings are uploaded to the remote server via the user’s communication device. The Virtual Trainer application is available as a set of remote server services. The server side includes matching of the obtained data with the pattern or results of other users. The matching results are used to provide correcting feedback for the user. The correcting feedback can be provided via user’s communication device, computer, digital assistant or mobile phone. This feedback does not inform on the correctness of performance of a particular movement in terms of the structure of the movement that forms it. One of the server services implies the possibility of remote participation in the training of a human trainer, involved in the exercise preparation.

Conclusions. According to the findings, the common feature of all the examined systems of motor skill formation is that they solve the problem of creating a specialized environment, which includes objects of interaction with a person or equivalent models. These actions are designed to construct a safe-to-use environment controlled well by technical means. The educational effect of this technologically rich environment is provided by the organization of feedback needed to perform the sensory correction of athlete’s movements. The possibility of control depends on the ability of a trainer to set an algorithm of actions for an athlete and monitor the characteristics of his motor activity. The technical effect in this case is represented by changes in the environment and is estimated by the typical change in the indicators of motion sensors, fixed on the working objects or parts of the human body. Mechanical devices, optical tracking systems, electromagnetic tracking systems and inertial systems are used as motion detectors.

One of the main conditions for creating a workspace is ensuring autonomic control, intended not only for decreasing the degree of involvement in training of qualified personnel, but also for reducing the response time of the elements of the training environment to athlete’s actions, which is crucial in the case of motor skills.

It is also possible to use new techniques to arrange the developing environment and implement feedback. First of all it refers to the organization of team work and methodical support, based on the use of the results of psychological, psycho-physiological and pedagogical research in the field of formation of motor skills. Here the main drawback of the earlier systems should be eliminated, which is in the fact that for assessment and self-assessment of athlete’s motor activity the authors almost invariably use the obvious, but theoretically wrong approach, based on the work with the visualization of the path of movement, which the student should mechanically reproduce, striving for the standard set by a more skilled athlete.

References

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Corresponding author:  kapil@yandex.ru