EA011541B1 - A method for determining the motion trajectory (orientation) of a person (sportsman) or the members thereof and a device for carrying out said method - Google Patents

Abstract

A 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

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

There is a method of registering movements of a person (athlete) or parts of his body (limbs), which consists in carrying out high-speed photography, entering images into a computer and its subsequent processing in order to calculate the trajectories of movement of both the person as a whole and its individual parts. This method has several disadvantages: low accuracy in determining the trajectory of movement due to different angles of the position of the subject and the lack of accurate referencing of the coordinates of individual body parts; the lengthy process of making calculations associated with the need to enter a large number of image frames in a computer and its analysis; assumes certain conditions of illumination of a person during filming; involves the presence of a person within the line of sight of the camera (s); has a high cost.

There is another method of registering human movements, which consists in placing elements sensitive to changes in their position in space at significant points of the human body (limbs, head, body), using information sensitive to the signals from these elements, 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 reflecting elements are used - tags that illuminate and carry out high-speed shooting using 3 or more television cameras connected using high-speed analog input channels from a specialized computer [1-3].

However, this method also requires the mandatory presence of a person within sight, the availability of additional equipment for highlighting tags, a device for implementing this method is characterized by 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 drawbacks: the need for a person to be exposed to electromagnetic or electrostatic fields; limited scope due to the finite sensitivity of the sensors; lower than optical methods accuracy, high cost.

The closest in essence (prototype) are the method of registration of human movements and the 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 of the human body, using information sensitive to the signals from these elements, and recording the information recorded by the computer with the help of a computer. person One three-coordinate microcontroller device for measuring angular accelerations (deviations) is placed on the human body, including three angular acceleration sensors, each of which are oriented in the direction of one of the three mutually perpendicular axes (X, Υ, Ζ) and record signals from the output of these sensors into the non-volatile memory information from which is then used for further processing.

The described method and device prototype have a number of disadvantages.

One of the drawbacks is the described method and device is the relatively low accuracy of the reconstruction (subsequent calculation) of the trajectory of the body part (arms, legs or torso) of a person (athlete), on which a three-coordinate microcontroller device measuring angular accelerations is fixed, which is due to the fact that 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 motion. With uniform motion, such sensors after the reaction time, measured as a rule, 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 aircraft of the integration chain connected to the sensor.

The fact that the angular acceleration sensors have a constantly accumulated measurement error with constant long-term movement in one direction also affects the accuracy of the recovery of the trajectory of movement.

There is a special area of knowledge - inertial navigation, in which it is proved that for more or less accurate recovery of the motion paths of a point by sensor readings, it is necessary to have readings not only of three-coordinate angular acceleration sensors at the point studied, but also three-dimensional linear acceleration sensors, as well as know the angle directions of movement compared with the direction of the north [5,6]. This means that every microcontroller measuring device, fixed at a significant point in the body, must have such a set of sensors.

In addition, for retrospective recovery of the trajectory of the entire body of one microcontroller device with the above set of sensors, mounted on one of the limbs

- 1 011541 is clearly not enough. It is necessary to have at least one such device with a set of sensors on each of their extremities and at least one set on the body (belt) of a person (athlete). Measuring devices with sensors must be attached to 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 movement of the hands and feet. The measuring device on the belt of a person will allow to conditionally restore the trajectory of the torso 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 a more or less accurate recovery of the trajectory of a person, at least five sets of microcontroller measuring devices with a full set of sensors are needed. For an even more accurate reconstruction of the trajectory of human movement, it is necessary to increase the number of measuring systems and fix them on each moving fragment of the human body.

The aim of the present invention (method and device) is to improve the accuracy of determining (reconstructing) the trajectory of movement (orientation) of a person (athlete) or an individual part of it. In this case, the method and device should be free from the above disadvantages, namely, it would not be required for the implementation of mandatory external exposure (illumination) of the subject, binding to a specific limited area (sensor range), mandatory human presence in the line of sight and a certain orientation regarding sensor-receiving means.

This goal is achieved by the fact that in the method of registration of the trajectory of movement (orientation) of a person (athlete) or its individual parts, the method consists in placing elements (three-coordinate autonomous measuring devices) sensitive to changes in their position in space and able to determine the complete spatial movement of these points, using the signal-sensitive means of these elements, record the information received from them into memory (autonomous wearable devices), counts 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 human body, a person’s body is placed on it depending on the required reconstruction accuracy from 5 to 11 three-coordinate autonomous measuring devices, each of which includes three sensors of angular and linear accelerations (three semiconductor gyroscopes and accelerometers ), each of which is oriented in the direction of one of three mutually perpendicular axes (X, Υ, Ζ), and a semiconductor compass. The signals from the outputs of these sensors are digitized at a time interval of about 1 ms, they are pre-processed on the built-in microcontroller (scaled, normalized, compressed) and the signals are recorded in P1agy (nonvolatile) memory, information from which is then read into the computer via a fast interface (for example , I8B) and used for further processing - reconstruction of the trajectory of movement of the human body.

The task is also solved by the fact that the means for determining the movement of a given point is made in the form: three oriented in three mutually perpendicular axes (X, Υ, Ζ) angular acceleration sensors (semiconductor gyroscopes), three oriented in three mutually perpendicular axes of linear acceleration sensors (semiconductor 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-digital converter, the output of which is connected to a mic okontrollerom whose output is connected to R1a§y (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.

Large memory (non-volatile) memory can be implemented either as a non-detachable built-in (soldered) memory, or as an external memory memory inserted into a special slot (slot), for example, conventional MiF MeFa Sagb (MMS) or Sesig Eschya1 Sagb (8Ό) cards.

An example implementation of the method. To implement the described method, small-sized microcontroller stand-alone devices are used, powered by batteries, i.e., in working condition, they are not connected with any other device by wires. The set of sensors contains three mutually perpendicular angular acceleration sensors — semiconductor gyroscopes (oriented along the X, Υ and Ζ axes), three mutually perpendicular linear acceleration sensors — 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 into a digital form - digitized. The digitized signals are sent to the corresponding inputs of the microcontroller, which perform the preliminary signal processing operations (scaling, normalizing, calculating the absolute increments for each of the 3 axes, and Ζ). Further, the set of increments in three coordinates is written in a compressed form into the P1aAG large-volume memory along with time stamps. Such measuring devices are attached to at least 5 significant points of the athlete's body - wrists, ankles and belt. This allows the athlete to perform arbitrary exercises fairly accurately (without taking into account movements of the hands and feet, and also without taking into account possible bends and turns of the torso and head), with high speed (up to 1000 measurements per second) and

- 2 011541 quite a long time (for example, with a memory capacity of 8 GB of Yaky memory - approximately 8 minutes) at an arbitrary distance and, if necessary, outside the line of sight, record all its movements. After an athlete completes an exercise kit, the recorded data from the memory can be quickly read to an external computer via a high-speed interface, for example, the I8B. The read data in an external computer can be used to restore the trajectories of movement of the main parts of the athlete’s body and to obtain on the computer screen a schematic image of a person - an athlete performing certain exercises. Reproduction of recorded information in a slow or accelerated pace, for example, will allow you to identify errors or inaccuracies in the movements of the athlete when performing certain exercises. It is obvious that such a 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 areas, etc.

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

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

FIG. 1 shows a functional diagram of a device for detecting the trajectory of a person or an individual part of it (arms, legs, torso) - a three-coordinate autonomous wearable measuring microcontroller device containing three (1, 2 and 3) semiconductor sensors of angular acceleration (semiconductor gyroscope) located on mutually -perpendicular axes (X, Υ, Ζ), three semiconductor sensors (4, 5 and 6) linear accelerations (semiconductor accelerometers) located on mutually perpendicular axes (X, Υ, Ζ), sensor - semi odnikovy compass 7, voltage sensor 8, an analog multiplexer 9, an analog-digital converter 10, microcontroller 11, sensor control unit 12, a high-speed interface I8V 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 6, semiconductor compass 7 and supply voltage sensor 8 are connected to the inputs of analog multiplexer 9, the output of which is connected to the input of analog-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 sensors 1-8, another group of inputs / outputs of the microcontroller 11 is connected to the inputs / outputs of the high-speed I8B interface 13, the output of which can be connected with a computer, and the third group of I / Os of the microcontroller 11 is connected to the I / Os of the high-speed Iaky (non-volatile) memory 14.

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

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

The device works as follows. All three semiconductor sensors of angular accelerations 1, 2 and 3 are located on mutually perpendicular axes (X,, Ζ) made, for example, on the basis of semiconductor gyroscopes ΕΒ.8150ΕΒ [7] of the company Apalod ES1CP5. When the sensor rotates around the measuring axis (when the position of the control point changes during human movement), a voltage equivalent to the angle of rotation of the sensor per unit of time is generated at the signal output relative to the average supply voltage, i.e. angular velocity (speed of rotation of the sensor). All three semiconductor sensors of linear accelerations 4, 5 and 6 are located on mutually perpendicular axes (X,, Ζ) made, for example, on the basis of semiconductor accelerometers ΑΌΧΕ202Ε [8] of the company Apalod ES1CP5. When the sensor is displaced along the measuring axis (when the control point is shifted along the axis during human movement), a voltage equivalent to the sensor shift per unit of time is generated at the signal output relative to the average supply voltage, i.e. equivalent to linear velocity. The semiconductor compass 7 can be made, for example, on the basis of a three-coordinate microcircuit NMS1055 [9] of the company Nopsu \ rc11. At its output, the voltage is equivalent to the deviation of the sensor axis from the north direction. Sensor 8 is designed to measure the supply voltage of the sensors in order to calculate the average point of the supply voltage. The middle point 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 are fed to the input of the analog-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 interface I8B 13, the output of which can be

- 3 011541 connected to an external computer for fast reading of accumulated data. The third inputs / outputs of the microcontroller 11 are connected to the inputs / outputs of the large-capacity P1a8I (non-volatile) memory 14, which serves to accumulate data. The memory module P1a8Y 14 can be executed, for example, on the basis of a soldered IC ΌΒ45ΌΒ642Ό chip [10] or on the basis of an ordinary MiScheF card inserted into a special slot, for example, by ZiiOEk company. The nodes of the analog multiplexer 9, analog-digital converter 10, microcontroller 11, and interface 8В 13 are the internal nodes of the modern C8051P342 chip [11] used by the company 8 of the SoboFpec.

The microcontroller 11 with a high speed, several hundred times higher than the frequency of the registration of the trajectory of a person, 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 by calculating the difference between the output signal and the midpoint of the supply voltage measured by sensor 8. The signals from the outputs of all the sensors allow us to calculate the offset along each of the X, Υ and Ζ axes, which is saved every millisecond in P1a § 14. 14. Since for the comprehensive registration of movements several such devices can be used, for example, mounted on the trunk and limbs, it is used to synchronize the recording in the microcontroller 11. rogrammny real-time clock (Kea1 T1te S1osk - CCC), which can be synchronized by i8V 13 interface.

For a given registration period, for example, 1 ms, the number of bytes written for 1 ms is 4 (1 hd - long without a sign number) for recording the current time + 3 coordinates * 4 bytes for each coordinate, a total of 16 bytes. It is obvious that 16 Kbytes of data are saved for 1 second. With such a write speed, the memory chip of memory P45A64ΆΤ642, having a capacity of 8 MB, is enough for 500 seconds (8 minutes) of recording, and MMS cards with a capacity of 128 M - for 8000 s or 500 minutes (approximately 8 hours). This is quite enough for a man-athlete to perform any exercise that requires registration. When the device is connected to an external computer via the i8B 13 interface, the accumulated data is read from the device into the computer.

The advantages of the proposed method and device consist in a higher accuracy of recording the trajectory of movement of the human body (athlete);

no need for human exposure to external electrostatic, electromagnetic or other fields harmful to health;

the test person is completely free of territorial restrictions (not connected with anything either by wires, or by fasteners, or by the equipment used, or by the zone of visibility or radio reception);

the test person is free from a certain orientation in space, for example, so that the sensors are illuminated or rotated towards the receiving antenna or the photodetector; the registration rate with this method and device is significantly higher than in opposed devices, since not limited by the need for manual measurements, bandwidth of communication channels, etc.

the devices used in the claimed method are autonomous, i.e. during measurements and registration, they have neither a connection with a computer nor an external power supply; consequently, they have no wires and other elements that interfere with the natural movement of the tested person.

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Claims (2)

CLAIM 1. The method of registration of the trajectory of movement of a person or its individual parts, consisting in that elements that are sensitive to a change in their position in space are placed at significant points of the human body, using information sensitive to the signals of these elements of the element, the information received from them is processed using an external computer to obtain data on the nature of the trajectory of a person’s movement, characterized in that on the arms, legs, and belt - 4 011541 harnesses place at least five three-coordinate autonomous microcontroller displacement measurement devices, including three angular and linear acceleration sensors, each of which orient in one of three mutually perpendicular axes and three-coordinate semiconductor compass, and the signals obtained from their outputs through an analog the multiplexer is fed to an analog-to-digital converter, digitized and recorded into non-volatile memory, data from which can be read through high-speed an interface to an external computer for further processing. 2. The device according to claim 1, characterized in that the means of determining movement is made in the form of three pairs oriented in three mutually perpendicular axes X,, Ζ of sensors of angular and linear accelerations and a three-coordinate semiconductor compass connected to the inputs of an analog multiplexer, the output of which is connected with the input of an analog-digital converter, the output of which is connected to the inputs of the microcontroller, the inputs / outputs of which are also connected to the E-memory unit and the high-speed I8B interface.