WO2008075926A1

WO2008075926A1 - Method for determining the motion trajectory (orientation) of a person (sportsman) or the members thereof and a device for carrying out said method

Info

Publication number: WO2008075926A1
Application number: PCT/MD2007/000004
Authority: WO
Inventors: Eugen Moraru; Oleg Nicolaiciuc
Original assignee: Eugen Moraru; Oleg Nicolaiciuc
Priority date: 2006-12-21
Filing date: 2007-11-09
Publication date: 2008-06-26
Also published as: EA011541B1; EA200701569A2; EA200701569A3

Abstract

The inventive method for method for determining the motion trajectory of a person or the members thereof (arms, legs or body) consists in fixing to the body at least five self-contained three-dimensional displacement microcontroller devices comprising three angular acceleration sensors (gyroscopes) (1, 2, 3), each of which is oriented in the direction of one of mutually perpendicular axes (X, Y, Z), three linear acceleration transducers (accelerometers) (4, 5, 6), each of which is oriented in the direction of one of mutually perpendicular axes (X, Y, Z), and a three-dimensional semiconductor compass, the output signals of which are multiplexed, digitized and recorded in a Flash bulk memory, and, once the task is performed, said signals can be fetched, via a high-speed USB interface, into an external computer, for recovering the motion trajectory of the entire body or of the members thereof.

Description

METHOD FOR DETERMINING THE TRAJECTORY OF MOTION (ORENTATION)

HUMAN (ATHLETE) OR SEPARATE ITS PARTS

AND DEVICE FOR ITS IMPLEMENTATION

The invention relates to the field of sports medicine and more specifically relates to a method for recording the movement path (orientation) of a person (athlete) or its individual parts and device for its implementation.

A known method of recording the movements of a person (athlete) or parts of his body (limbs), which consists in carrying out high-speed photography, inputting images into a computer and its subsequent processing in order to calculate the motion paths of both the person as a whole and its individual parts. This method has several disadvantages: low accuracy of determining the trajectory of motion due to various angles of the position of the subject and the lack of accurate reference coordinates of individual parts of the body; a lengthy process of computing, associated with the need to enter a large number of image frames into a computer and analyze it; involves certain lighting conditions of a person during the shooting; involves a person within the direct line of sight of movie camera (s); has a high cost.

There is another way of registering human movements, consisting in the fact that at sensitive points of the human body (limbs, head, torso) are placed elements that are sensitive to changes in their position in space, using information sensitive to the signals of these elements means record information received from them, and process the recorded information using a computer to obtain data on the nature of human movements. In the known method, a number of passive reflective elements are used — marks that illuminate and conduct high-speed shooting using 3 or more television cameras connected using high-speed analog input channels with a specialized computer [1-3].

However, this method also requires the presence of a person within sight, the availability of additional equipment for highlighting tags, a device for implementing this method is characterized by a high cost.

A number of similar methods are also known, based on measuring distances to marks on certain parts of the human body by measuring other physical quantities, based on the use of the Hall effect, piezoresistive, electromagnetic and electrostatic sensors. All these methods and devices that implement them have common disadvantages: the need for exposure to humans by electromagnetic or electrostatic fields; limited scope due to the finite sensitivity of the sensors; lower accuracy than optical methods, high cost.

The closest in essence (prototype) are a method of recording human movements and a device for its implementation, described in [4]. The described method consists in placing elements sensitive to changes in their position in space at significant points in the human body, using the means sensitive to the signals of these elements, recording information received from them, and processing the recorded information using a computer to obtain data on the nature of movements person. A three-coordinate microcontroller device for measuring angular accelerations (deviations) is placed on the human body, including three angular acceleration sensors, each of which is oriented in the direction of one of three mutually perpendicular axes (X, Y, Z) and the signals from the output of these sensors are recorded in non-volatile memory , information from which is then used for subsequent processing.

The described method and device prototype have several disadvantages.

One of the disadvantages of the described method and device is the relatively low accuracy of reconstruction (subsequent calculation) of the trajectory of the body part (arm, leg or body) of a person (athlete), on which a three-coordinate microcontroller device for measuring angular accelerations is fixed, due to the fact angular deviation sensors measure short-term relative angular deviations, i.e. their readings depend on the initial position of the object, and give the result only in a short period of time with accelerated movement. With uniform motion, such sensors after a reaction time, usually measured in tens of microseconds, show a zero result. The reaction time of these sensors is determined by the time constant of the internal or external RC integration circuit connected to the sensor.

The fact that the angular acceleration sensors have a constantly accumulating measurement error with constant continuous movement in one direction also affects the accuracy of restoring the trajectory of motion.

There is a special area of knowledge - inertial navigation, in which it is proved that for more or less accurate restoration of the point's trajectories according to the sensor readings, it is necessary to have at the studied point the readings of not only three-coordinate angular acceleration sensors, but also three-coordinate linear acceleration sensors, and also know the angle direction of travel compared to direction to the north [5,6]. This means that each microcontroller measuring device, mounted on a significant point in the body, must have such a set of sensors.

In addition, for retrospective restoration of the trajectory of the entire body of one microcontroller device with the above set of sensors, mounted on one of the limbs is clearly not enough. It is necessary to have at least one such device with a set of sensors on each of their limbs and at least one set on the body (belt) of a person (athlete). Measuring devices with sensors must be fixed on the last free fragments of the limbs, for example, on the wrists and ankles. Obviously, in this case it will not be possible to restore the trajectories of the hands and feet. The measuring device on the human belt will allow you to conditionally restore the trajectory of the body without taking into account possible turns, for example, the lower part of the body relative to the upper, or bends of the body. Thus, for more or less accurate restoration of the trajectory of a person’s motion, at least five sets of microcontroller measuring devices with a full set of sensors are needed. For even more accurate reconstruction of the trajectory of a person’s movement, it is necessary to increase the number of measuring systems and fix them to each moving fragment of the human body.

The aim of the present invention (method and device) is to increase the accuracy of determination (reconstruction) of the trajectory of movement (orientation) of a person (athlete) or its individual part. At the same time, the method and device should be free from the above disadvantages, namely, it would not be required to carry out mandatory external exposure (illumination) of the test subject, binding to a certain limited territory (sensor coverage area), mandatory presence of a person in a line of sight and a certain orientation relative to the signal receiving means sensors.

This goal is achieved by the fact that in the method of recording the trajectory of movement (orientation) of a person (athlete) or its individual parts, consisting in the fact that at significant points in the human body are placed elements (three-coordinate autonomous measuring devices) that are sensitive to changes in their position in space and capable of determining the total spatial displacements of these points, using the means sensitive to the signals of these elements, write the information received from them into memory (autonomous wearable devices), yvayut synchronized data received from the portable autonomous device in a computer and treated to obtain the information reconstruction movement trajectories as individual parts of the human body and the whole body in general. According to the invention, for accurate reconstruction of the trajectory of a person’s body, a person is placed on it (body) depending on the required accuracy of reconstruction from 5 to 11 three-coordinate autonomous measuring devices, each of which includes three angular and linear acceleration sensors (three semiconductor gyroscopes and accelerometers), each of which is oriented in the direction of one of the three mutually perpendicular axes (X, Y, Z), and a semiconductor compass. The signals from the outputs of these sensors are digitized with a time interval of about 1 millisecond, pre-processed by the built-in microcontroller (scaled, normalized, compressed) and written to Flash memory (non-volatile) memory, the information from which is then read into a computer via a fast interface (for example, USB ) and used for subsequent processing - reconstruction of the trajectory of the human body.

The problem is also solved by the fact that the means of determining the movement of a given point is made in the form of: three angular acceleration sensors (semiconductor gyroscopes) oriented along three mutually perpendicular axes (X, Y, Z), three linear acceleration sensors (semiconductor) oriented on three mutually perpendicular axes accelerometers), and a semiconductor compass connected to the inputs of an analog multiplexer, the output of which is connected to the input of an analog-to-digital converter, the output of which is connected to a mic controller whose output is connected to a Flash (nonvolatile) memory large volume and the other output is connected to the high speed interface which can be connected to the computer reading the stored data.

A large flash memory (non-volatile) can be made either as a one-piece internal (soldered) memory, or as an external flash memory inserted into a special slot (slot), for example, an ordinary Multi Media Card (MMC) or Secure Digital Card (SD) ) cards.

An example implementation of the method. To implement the described method, small-sized microcontroller autonomous devices powered by rechargeable batteries are used, i.e. in working condition not connected by wires to any other device. The set of sensors contains three mutually perpendicular sensors of angular accelerations - semiconductor gyroscopes (oriented along the axes X, Y and Z), three mutually perpendicular sensors of linear accelerations - semiconductor accelerometers and a semiconductor compass. The output signals of all sensors through an analog multiplexer are fed to the input of an analog-to-digital converter, where they are converted to digital form - they are digitized. The digitized signals are fed to the corresponding inputs of the microcontroller, which performs the operations of preliminary signal processing

(scaling, normalization, calculation of absolute increments along each of the 3x axes X, Y and Z). Next, a set of increments in three coordinates is written in compressed form to a large Flash memory along with timestamps. Such measuring devices are fixed on at least 5 significant points of the athlete’s body - wrists, ankles and belt. This allows the athlete to perform arbitrary exercises quite accurately (without taking into account the movements of the hands and feet, as well as without taking into account possible bends and turns of the body and head), at a high speed (up to 1000 measurements per second) and for a rather long time (for example, with capacity Flash memory of 8GB - about 8 minutes) at an arbitrary distance and, if necessary, outside the line of sight, record all its movements. After the athlete performs a set of exercises, the recorded data from Flash memory can be quickly read into an external computer via a high-speed interface, for example, USB. The read data in an external computer can be used to restore the motion paths of the main body parts of the athlete and obtain on the computer screen a schematic image of a person - an athlete performing certain exercises. Playing back recorded information in slow motion or accelerated pace, for example, will allow you to identify errors or inaccuracies in the movements of the athlete when he performs certain exercises. Obviously, this method can also be used in a number of other practical areas, for example, for the formation of human movements when creating animated films, in military fields, etc.

The described method provides high measurement accuracy, does not require harsh lighting conditions or irradiation of a person with any fields, does not limit the area of a person; provide a higher speed of data recording than high-speed photography, allow you to register the movement of a person (or parts thereof) for a considerable time and at a considerable distance.

The description of the device is illustrated by a description of a specific variant of its implementation and the attached drawing, which shows a functional diagram of the device.

Figure l presents a functional diagram of a device for recording the trajectory of a person or a part of it (arms, legs, torso) - a three-coordinate autonomous wearable measuring microcontroller device containing three (1, 2 and 3) semiconductor angular acceleration sensors (semiconductor gyroscopes) located on mutually perpendicular axes (X, Y, Z), three semiconductor sensors (4, 5 and b) of linear accelerations (semiconductor accelerometers) located on mutually perpendicular axes (X, Y, Z), the sensor - along uprovodnikovy compass 7, voltage sensor 8, an analog multiplexer 9, an analog-digital converter 10, microcontroller 11, sensor control unit 12, the high-speed USB interface 13 and nonvolatile memory 14 of large volume. The outputs of all three mutually perpendicular angular acceleration sensors 1, 2 and 3, three mutually perpendicular linear acceleration sensors 4, 5 and b, the semiconductor compass 7 and the voltage sensor 8 are connected to the inputs of the analog multiplexer 9, the output of which is connected to the input of the analog-to-digital converter 10, the output of which is connected to the input of the microcontroller 11, one group of outputs of which is connected to the control inputs of the sensor control unit 12, the outputs of which are connected to the corresponding inputs of each of the sensors ovs 1-8, another group of inputs / outputs of the microcontroller 11 is connected to the inputs / outputs of the high-speed USB interface 13, the output of which can be connected to a computer, and the third group of inputs / outputs of the microcontroller 11 is connected to the inputs / outputs of the high-speed Flash (non-volatile) memory 14 .

The method of recording human movements will become clear from the description of the operation of the device.

At significant points on the human body (of the limbs, head), elements are placed that are sensitive to their change in position in space. For example, for minimal accuracy in reconstructing the movement of the whole body on the wrists, ankles of the legs and the belt, one three coordinate autonomous measuring microcontroller device is fixed according to the invention.

The device operates as follows. All three semiconductor angular acceleration sensors 1, 2 and 3 are located on mutually perpendicular axes (X, Y, Z) made, for example, on the basis of ADXRS 15 OEB [7] semiconductor gyroscopes manufactured by Apalog Devices. When the sensor rotates around the measuring axis (when the position of the control point changes during the movement of a person), a voltage equivalent to the angle of rotation of the sensor per unit time is generated at the signal output relative to the average value of the supply voltage, i.e. angular velocity (speed of rotation of the sensor). All three semiconductor linear acceleration sensors 4, 5 and 6 are located on mutually perpendicular axes (X, Y, Z) made, for example, on the basis of ADXL202E [8] semiconductor accelerometers from Apalog Devices. When the sensor is shifted along the measuring axis (when the control point is shifted along the axis during the movement of a person), a voltage equivalent to the sensor shift per unit time is generated at the signal output relative to the average value of the supply voltage, i.e. equivalent to linear speed. The semiconductor compass 7 can be performed, for example, on the basis of a three-coordinate microcircuit HMC1055 [9] from Nopeuwell. At its output, the voltage is equivalent to the deviation of the sensor axis from the north direction. The sensor 8 is designed to measure the supply voltage of the sensors in order to calculate the midpoint of the supply voltage. The midpoint of the supply voltage is necessary to calculate the positive or negative signals at the output of the sensors. The signals from the outputs of all sensors are fed to the inputs of the analog multiplexer 9, and from its output fed to the input of an analog-to-digital converter 10, the outputs of which are connected to the inputs of the microcontroller 11, the outputs of which are connected to the inputs of the sensor control unit 12, the outputs of which are connected to the corresponding inputs of all sensors. Sensor control is necessary to minimize measurement errors. Other inputs / outputs of the microcontroller 11 are connected to the inputs / outputs of the high-speed USB 13 interface, the output of which can be connected to an external computer for quick reading of the accumulated data. The third inputs / outputs of the microcontroller 11 are connected to the inputs / outputs of the Flash unit (non-volatile) memory 14 of a large volume, which serves to accumulate data. Flash memory block 14 can be made, for example, on the basis of a soldered AT45DB642D microcircuit [10] or on the basis of a conventional Multimedia card inserted into a special slot, for example, SшiDisk. The nodes of the analog multiplexer 9, the analog-to-digital converter 10, the microcontroller 11, the USB 13 interface are internal nodes of the used modern C8051F342 [l 1] microcircuit manufactured by Silicop Labors.

The microcontroller 11 with a high speed, several hundred times higher than the frequency of registration of the trajectory of human movement, sequentially polls the inputs of the multiplexer 9, and the analog-to-digital converter 10 converts them into digital form. The microcontroller then filters the data and normalizes the data, calculating the difference between the output signal and the midpoint of the supply voltage measured using sensor 8. The signals from the outputs of all sensors allow you to calculate the offset along each of the X, Y, and Z axes that is stored every millisecond in Flash 14. Since several such devices can be used for comprehensive registration of movements, mounted, for example, on the trunk and limbs, to synchronize recording in microcontroller 11, Real-time gram timer (Real Time Closk - RTC), which can be synchronized via USB 13.

For a given registration period, for example, 1 ms, the number of bytes recorded in 1 ms is 4 (lopg is a long unsigned number) for registering the current time + 3 coordinates * 4 bytes per coordinate, a total of 16 bytes. Obviously 16 seconds of data is saved in 1 second. At this write speed, the AT45DB642 Flash memory chip, which has a capacity of 8 MB, is enough for 500 seconds (8 minutes) of recording, and an MMC card with a capacity of 128M can last 8000 seconds or 500 minutes (about 8 hours). This is quite enough for a human athlete to perform any exercise that requires registration. When connecting the device to an external computer via the USB 13 interface, the accumulated data is read from the device to the computer.

The advantages of the proposed method and device are: • higher accuracy of recording the trajectory of the body of a person (athlete);

• no need for exposure to humans by external electrostatic, electromagnetic or other fields harmful to health;

• the test person is completely free from territorial restrictions (not connected to anything with wires or mounts, nor with the equipment used, nor with the zone of visibility or reliable radio reception);

• the test person is free from a certain orientation in space, for example, so that the sensors are lit or turned towards the receiving antenna or photodetector;

• the registration speed with this method and device is significantly higher than in opposed devices, because not limited to the need for manual measurements, the bandwidth of communication channels, etc.

• the devices used in the claimed method are autonomous, i.e. during measurements and registration, they have neither communication with a computer nor external power, therefore, they do not have wires or other elements that interfere with the natural movement of the test person.

Literature:

1. Achel Mulder - Schoof of Kipesiologu, Simop Fraser Upiversitu, 8 Mau 1998.

2. Wipegipeeripes Technology & Systems / Superfluo: ELITE Data.

3. Selsrot AB: SELSPOT II Date; Northem Digital Ips. : Ortotrak Date.

4. RU 2257846 Cl "Method for registering human movements and a device for its implementation

5. V.V. Podzubny Restrictive filtering in navigation systems / Scientific and Technical Library of Ternopol State Polytechnical University, http: //library.tetu,edu.ua/resources/fileserver, vroddl.рdf.

6. IM. Danilin, EM. Medvedev, CP. Melnikov - Laser location of land and forest, Chapter 4, Navigation support for laser location, http://www.ssga.ru/metodich/les/j4.html

7- Mtp: //www.atia1og.com/UploadedFiles/Bvaluation_ _ιι Boards / Tools / 9303074ADXRS, 150EB_ _d 0.pdf

8- http: / '/ www.analog.com/UploadedFilcs,Oata_Sheets/ADXL202E.pdf

9.Http: //www.ssec.hoдeywell.comUmagnetic/datasheets/hmc l Q55.pdf

10.http: //www.atmel.cotti/dvn/resoιιrces/prod_documents/doc3542.pdf

11. h1tp: //www.silabs.com/public/docmcnts/tpub doc / dsheet ^/ MicrocontrollersΛJSB / en / C8051F34x.pdf

Claims

CLAIM

1. The method of recording the trajectory of movement (orientation) of a person (athlete) or its individual parts (arms, legs, torso), consisting in the fact that at sensitive points on the human body are placed elements that are sensitive to changes in their position in space, using sensitive to the signals of these elements of the tools record the information received from them, process the recorded information using an external computer to obtain data on the nature of the trajectory of a person’s movement, characterized in that at least five are placed on the human body (on arms, legs and belt) of three-coordinate autonomous microcontroller devices for measuring displacement, including three angular and linear acceleration sensors, each of which is oriented in the direction of one of three mutually perpendicular axes (X, Y and Z) and a three-coordinate semiconductor compass, and those obtained from them outputs through an analog multiplexer, are fed to an analog-to-digital converter, digitized and written to Flash (non-volatile) memory, data from which can be read out via a high-speed interface to an external computer for further processing.

2. A device, characterized in that the displacement determination means is made in the form of three pairs of angular and linear acceleration sensors oriented along three mutually perpendicular axes (X, Y, Z) and a three-axis semiconductor compass connected to the inputs of an analog multiplexer, the output of which is connected to the input analog-to-digital converter, the output of which is connected to the inputs of the microcontroller, the inputs / outputs of which are also connected to the Flash memory unit and a high-speed USB interface.