RU137953U1 - DEVICE FOR DETERMINING THE POSITION OF THE OBJECT IN THE SPACE - Google Patents

Abstract

A device for determining the position of an object in space, containing an inductor, a three-axis magnetometer interacting with a computing unit, characterized in that the inductor is stationary and interacts with a current stabilizer that is interconnected with the computing unit, while the device contains digital three-axis accelerometer located on the object and a magnetometer, the outputs of which are connected directly to a computing unit containing a measured vector separation unit magnetic induction on the Earth’s magnetic field induction vector and the magnetic field induction vector of the inductance coil, as well as an angular coordinate calculation unit, a directional correction module of the magnetic field induction vector of the inductance coil and a linear coordinate calculation unit, while the magnetometer output is connected to the input of the separation unit of the measured magnetic vector induction, the first output of which is connected to the first input of the block for calculating the angular coordinates, and the second output is connected to the first input of the block of directional correction induction vector of the magnetic field of the inductor, the output of which is connected to an input of the calculation of linear coordinates and the accelerometer output is connected to the second input of the calculating angular coordinates whose output is connected to the second input of the correction direction of the induction vector of the magnetic field of the inductor.

Description

The proposed utility model relates to measuring technique, namely, devices for determining the linear and angular coordinates of an object freely moving in a space with six degrees of freedom. The device can be used in human-machine interfaces, as a gesture input device, in particular, in robotics for intuitive manual control of robotic manipulators (robot surgeon, robot sapper), in augmented and virtual reality technologies. In addition, the device allows you to control the position of various mechanisms and elements of technological equipment located in environments with a high degree of pollution.

A device is known according to the method of determining a location on the plane of an object having a magnetic moment according to autosw. USSR No. 1372261, G01R 33/02, with the help of which the component of magnetic induction of the magnetic field vertical to the plane is measured at three points by meters located on the axes of the Cartesian coordinate system lying in the plane with an additional measurement of the component of the Earth's magnetic field induction vertical to the plane. To obtain more accurate coordinates, the signal with the measured component of the Earth's magnetic field induction is subtracted from the signals measured at three points.

The disadvantages of the known device include the ability to determine the position of the object only in the Cartesian coordinate system on the plane and only if it is in the same plane with the meters. The determination of the angular position of the object is not carried out. In addition, the device contains a distributed on a plane system of four meters, which complicates its design, leads to an increase in its size and mass.

A known method for determining the coordinates of a magnetic field source according to the patent of Russian Federation No. 2452652, G01R 33/02, solves the problem of determining the coordinates of an object in space by moving the sensor carrier relative to the object and measuring the module of the magnetic induction vector of the object. The disadvantages of this method include the need for the carrier to carry out four measurements at different points in space with known coordinates. Therefore, it is required by some known methods to move the carrier and determine its coordinates at each measurement point. In this case, the immobility of the object in the process of measuring and moving the carrier is a prerequisite. Thus, the known method has an extremely low speed and extremely high implementation complexity. In addition, the known method does not allow to determine the angular position of the object.

As a prototype of the claimed device selected technical solution according to the patent of the Russian Federation No. 2171476, G01R 33/02 (options). The device for determining the position of an object according to the first embodiment includes one inductor that interacts with an alternating voltage generator, three three-component (three-axis) magnetosensitive sensors (magnetometers) and a system of converters and amplifiers for transmitting signals from magnetosensitive sensors to a computing unit.

The device according to the second embodiment includes two inductors located mutually perpendicular to the object and interacting with alternating voltage generators, three three-component magnetosensitive sensors and a system of converters and amplifiers for transmitting signals from magnetosensitive sensors to the computing unit.

The disadvantages of the prototype according to the first option include the impossibility of determining one of the three angular coordinates of the object.

The disadvantages of the prototype in the second embodiment include the need to use an additional inductor perpendicular to the first for the task of determining three linear and three angular coordinates of the object. This additionally complicates the design, increases energy consumption, size and weight of the positioned part of the device.

A common disadvantage of the device (in two versions) is the placement of inductors on the object, which leads to a significant increase in power consumption, size and weight of the positioned part of the device. In addition, the device requires the presence of three three-component magnetosensitive sensors located at the vertices of the triangle, which leads to a complication of the design and an increase in the size of the stationary part of the device.

The applicant's task is to create a device that is simple in design and easy to use to determine the linear and angular coordinates of an object that makes arbitrary movements in a certain limited area of three-dimensional space.

The technical result consists in quickly obtaining the exact coordinates of an arbitrarily moving object with a compact, economical device.

The technical result is achieved by the fact that in the device for determining the position of an object in a space containing an inductor, a three-axis magnetometer interacting with a computing unit, according to the invention, the inductor is stationary and interacts with a current regulator, which is controlled by a signal from the computing unit. The device also contains digital three-axis accelerometer and magnetometer located on the object, the outputs of which are connected directly to the computing unit. The computing unit contains: 1. a unit for separating the measured magnetic induction vector into the Earth's magnetic field induction vector and the magnetic field induction vector of the inductor; 2. block for calculating angular coordinates; 3 block correcting the direction of the vector of induction of the magnetic field of the inductor; 4. block for calculating linear coordinates. In this case, the magnetometer output is connected to the input of the separation unit of the measured magnetic induction vector, the first output of which is connected to the first input of the angular coordinate calculation unit, and the second output is connected to the first input of the direction correction module of the induction vector of the magnetic field of the inductor, the output of which is connected to the input of the calculation unit linear coordinates, the accelerometer output is connected to the second input of the angular coordinate calculation unit, the output of which is connected to the second input of the direction correction unit induction vector of the magnetic field of the inductor.

The use of a digital three-axis magnetometer and accelerometer makes it possible directly, bypassing the amplifier-conversion blocks, to transmit data on the measured magnetic field induction at a given point in space to a computing unit that implements an algorithm for determining the orientation and position of the object.

Thanks to MEMS technology (microelectromechanical systems), the size of the sensors is about 4 × 4 × 2 mm or less. A platform with a digital three-axis magnetometer and accelerometer is a positioned part of the device and is placed on the object. The dimensions of the platform can be about 20 × 20 × 5 mm or less.

Using a single three-axis magnetometer and a single three-axis accelerometer, combined on one platform, the computing unit implements an algorithm for determining the coordinates of an object based on information about the magnitude of the artificial magnetic field vector at a given point in space, together with an algorithm for determining the orientation of an object.

Using a miniature platform with two sensors and a single inductance coil can significantly reduce the complexity, size and power consumption of the device, increase the ease of installation and configuration. In addition, the placement of the platform with the sensors on the site instead of the inductor can significantly reduce the size and power consumption of the positioned part of the device.

In FIG. 1 shows a block diagram of a device for determining the position of an object in space.

The proposed device consists of an inductor 1, the inductor 1 interacts with a current stabilizer 2.

Digital three-axis magnetometer 3 and accelerometer 4 are located on the platform 5 so that their own coordinate axes are aligned. Platform 5 is rigidly fixed to the object. The magnetometer 3 and the accelerometer 4 interact with the computing unit 6, which contains: a unit for dividing the measured magnetic induction vector 7 into the Earth’s magnetic field induction vector and the magnetic field induction vector of the inductor 1; block for calculating angular coordinates 8; a unit for correcting the direction of the induction vector of the magnetic field of the inductor 9 and a unit for calculating linear coordinates 10. The output of the magnetometer 3 is connected to the input of the separation unit of the measured vector of magnetic induction 7, the first output of which is connected to the first input of the unit for calculating the angular coordinates 8, and the second output of the unit 7 is connected to the first input of the unit for correcting the direction of the induction vector of the magnetic field of the inductor 9, the output of which is connected to the input of the linear coordinate calculation unit 10, and the output of the accelero Etra 4 is connected to the second input of the calculation of the angular coordinate 8, whose output is connected to the second input of the correction direction of the induction vector of the magnetic field coil 9.

The inductor 1 has a cylindrical shape, the diameter is greater than or comparable with the length, the core is absent, the winding is made with an insulated wire, the winding turns are flush; the diameter of the coil, the number of turns of the winding and the cross-section of the wire are determined based on the problem to be solved, in order to provide the necessary positioning radius, power consumption and dimensions of the coil, it is necessary to control the inductance and electrical resistance of the coil in order to switch the polarity of its current for a given time interval (the test coil has base diameter 150 mm, 255 coils of wire with a diameter of 0.31 mm, made in 5 layers, resistance 28 Ohms, inductance 16 mH, and rated for current 0 , 7 A).

The magnetometer 3 and accelerometer 4 are made by MEMS technology and can be represented by both separate and combined sensors (for example, the combined sensor LSM303DLHC from STMicroelectronics).

Platform 5 is a printed circuit board on which a magnetometer 3 and an accelerometer 4 are located.

The computing unit 6 is a personal or single-board computer, while the internal units 7, 8, 9, 10 of the computing unit 6 are subroutines.

The device operates as follows.

The controlled current stabilizer 2 of the coil 1 supplies a constant current of a certain value to the coil. The polarity of the current is set by the signal generated by the computing unit 6. The current passing through the coil 1 creates a magnetic field. The artificial magnetic field of coil 1 is added to the Earth’s magnetic field and magnetometer 3 measures the magnetic induction vector of the resulting field. At the same time, the accelerometer 4 measures the acceleration vector of gravity.

The readings of sensors 3 and 4 are transmitted in digital form to the computing unit 6. After receiving the readings of the sensors 3 and 4, the computing unit 6 sends a polarity reversal signal to the controlled current stabilizer 2. The stabilizer 2 reverses the current polarity (for example, there was a current of 1 A, and becomes -1 A), and the process repeats.

To determine the linear and angular coordinates of the object by the magnetic induction vector measured by the magnetometer 3 and the gravitational acceleration vector measured by the accelerometer 4, the computing unit performs the following operations.

At the first step, block 7 separates the measured magnetic induction vector into the Earth’s magnetic field induction vector and the magnetic field induction vector of the inductor 1. Separation is made by adding and subtracting two successive measurements of magnetometer 3 obtained with opposite current polarity of coil 1 and, respectively, with opposite directions of the magnetic field induction vector of coil 1:

,

,

,

,

,

,

,

,

- текущее измерение;Where

- current measurement;

- вектор индукции магнитного поля Земли;

- vector of the induction of the Earth's magnetic field;

- вектор индукции магнитного поля катушки 1 (меняет направление на противоположное при переключении полярности тока стабилизатором 2);

- the induction vector of the magnetic field of coil 1 (reverses the direction when the current polarity is switched by stabilizer 2);

- предыдущее измерение.

- previous measurement.

In the next step, in the direction of the found magnetic field vector of the Earth’s magnetic field and the gravitational acceleration vector measured by the accelerometer 4, the angular coordinates of the object in block 8 are calculated in a known manner [1].

In the third step, the obtained information on the angular coordinates of the object is used in block 9 to correct the direction of the found induction vector of the magnetic field of coil 1. In general, the object has an arbitrary orientation unknown in advance, and magnetometer 3 measures the induction vector of the magnetic field of coil 1 in its system coordinates, therefore, it is necessary to translate this vector from the coordinate system of the sensor into the coordinate system associated with the fixed coil 1. For this purpose, the direction of the inductor of the magnetic field of the coil 1 by reversing it at angles equal to the angular coordinates of the object. The rotation of the vector is carried out, for example, using rotation matrices [2].

At the last step, block 10, based on the adjusted magnetic field induction vector of the coil 1, determines the linear coordinates of the object relative to the coil 1. The transition from the magnetic field induction vector of the coil 1 to the coordinates of the object is carried out, for example, using a table-defined function. The table is an array of space points selected with a certain step, where each point is associated with a magnetic induction vector created by an inductor 1 at a given point in space. Calculation of vectors is performed using the law of Bio-Savard-Laplace [3, p. 205], using modern software, for example, the mathematical package MATLAB. To determine the linear coordinates of the object, it is necessary to find in the table the vector closest to the magnetic field induction vector of coil 1 obtained in the previous step. The coordinates associated with this vector are the desired coordinates of the object.

Information sources:

1. Implementing a Tilt-Compensated eCompass using Accelerometer and Magnetometer Sensors / Talat Ozyagcilar // Freescale Semiconductor Application Note. - Document Number AN4248, Revision 3, January 2012.

2. The rotation matrix [Electronic resource] // Wikipedia. - Access mode: http://ru.wikipedia.org/wiki/Gold_Matrix.

3. Physics course: textbook. manual for universities / Trofimova T.I. - 11th ed. - M.: Publishing Center "Academy", 2006. - 560 p.

4. Auto USSR No. 1372261, G01R 33/02

5. RF patent No. 2452652, G01R 33/02

6. RF patent No. 2171476, G01R 33/02

Claims (1)

A device for determining the position of an object in space, containing an inductor, a three-axis magnetometer interacting with a computing unit, characterized in that the inductor is stationary and interacts with a current stabilizer that is interconnected with the computing unit, while the device contains digital three-axis accelerometer located on the object and a magnetometer, the outputs of which are connected directly to a computing unit containing a measured vector separation unit magnetic induction onto the Earth’s magnetic field induction vector and the magnetic field induction vector of the inductor, as well as the unit for calculating the angular coordinates, the correction unit for the direction of the induction vector of the magnetic field of the inductor and the unit for calculating linear coordinates, while the magnetometer output is connected to the input of the separation unit of the measured magnetic vector induction, the first output of which is connected to the first input of the block for calculating the angular coordinates, and the second output is connected to the first input of the block of directional correction induction vector of the magnetic field of the inductor, the output of which is connected to an input of the calculation of linear coordinates and the accelerometer output is connected to the second input of the calculating angular coordinates whose output is connected to the second input of the correction direction of the induction vector of the magnetic field of the inductor.

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