SU1569724A1 - Two-components acceleration transducer - Google Patents

Abstract

This invention relates to a measurement technique. The self-adjusting acceleration sensor allows determining the magnitude and direction of the acceleration by measuring the sign and magnitude of the output voltage of two Hall sensors associated with an inertial mass placed in a non-uniform magnetic field. For this, the inertial mass 4 is made of a diamagnetic material and is placed with the possibility of deviating from the axis of symmetry of the magnetic system. The magnetic system, which is rigidly connected to the housing 1, consists of four permanent magnets 2 with pole tips 3 of the hyperbolic profile and forms a magnetic quadrupole. The plates of two mutually perpendicular Hall sensors 5, 6 are associated with an inertial mass and are located parallel to the axis of symmetry of the magnetic system. 2 Il.

Description

The invention relates to a measurement technique, namely, devices for converting mechanical motion parameters to an electrical signal.

The aim of the invention is to improve the measurement accuracy by self-adjusting the sensor.

FIG. 1 shows the principal structural diagram of the proposed sensor; in fig. 2 is a block diagram of signal processing.

The sensor consists of a housing 1 connected to the moving object in which the magnetic system is fixed. The magnetic system consists of four magnets 2 (for example, cylindrical Samaritz cobalt magnets) with pole pieces 3. The pole tips have a cross section of hyperbola, placed so that the poles of the same name lie in opposite squares. In the center of the magnetic system, with the possibility of deviation from it (for example, on a stretch or suspension), an inertial mass 4, made of a diamagnetic material (bismuth, copper, etc.), is strengthened. Two interstate mass sensors are rigidly connected to each other by two perpendicular Hall sensors 5 and 6, which are mounted so that their plates are placed at an angle of 45 to the axes of the permanent magnets.

The acceleration sensor works as follows

SP

About WITH

J

KD

4b

315

Inertial mass 4 with Hall sensor plates, 5 and 6 is deflected by inertial forces proportional to acceleration in any direction on the XY plane (Fig. 1). The values of the output signals of the Hall sensors U,, U g change by values proportional to Hrsin C and Hrcoatf,

where H is the magnetic intensity

l at the location of the sensors, Hall; av is the angle compiled by the acceleration vector with the x axis.

The deviation of the inertial mass from the equilibrium position occurs until the inertial force acting on it is balanced by the ponderomotive force acting on the diamagnetic field placed in a non-uniform magnetic field.

The magnitude of the ponderomotive force is determined by the formula. Hj .. grad4r, where m is body mass;

x - magnetic susceptibility. The direction of the force depends on the sign of the magnetic susceptibility of the substance from which the inertia mass is made. 4. For diamagnetic bodies, the magnetic susceptibility is negative and such bodies are pushed out of the field with greater intensity. Considering that for a used magnetic system, the magnetic field strength is expressed by the formula

H

Mr. N.,

where Hv is the magnetic field strength at the pole tip j

r is the radius vector of the system. Taking into account that the magnitude of the magnetic field intensity is constant, we can write:

F m-x-gradH-Hor,

those. the greater the deviation of the inertial mass 4 from the axis of symmetry, the

0

five

0

five

0

five

more balancing ponderomotive force acting on it. Thus, when the acceleration is removed, the inertial mass returns to its original state.

In the proposed sensor, no special initial alignment is required, i.e. establishing inertial mass 4 and magnetically sensitive elements 5 and 6 connected to it at a certain point in the field, since the inertial mass, pushing out from any region of the field with a non-zero intensity, is spontaneously set along the axis of the magnetic system, where. In this way, the error associated with the initial setup error and the error of the subsequent reproduction of the initial reference point is eliminated, thereby improving the measurement accuracy.

The magnitude of the measured acceleration is proportional to the intensity of the magnetic field at the point of location of the Hall sensors. A comparative analysis of the output EMF of the Hall sensors, taking into account their signs, allows us to determine the magnitude of the acceleration, as well as its voltage. As an example, the following signal processing scheme is considered (FIG. 2).

The inputs 7 and 8 of the Hall sensors 5 and 6 are sequentially supplied with direct current from the source 9 of the stabilized current. Next, two parallel output signal processing circuits are used. The first includes two similar multipliers 10 and 11, the inputs of which are supplied by the Hall emf, the series-connected adder 12, the logarithm 13, the divider 14, the inverse logarithm 15 and the indicator 16. The unit sequentially performs the following operations:

U, .sinV b 7g / pCHw -

U2 -cHrcos - c., J

HCH ZlnHj.,

As a result, the indicator records a value proportional to the intensity of the magnetic field, i.e. a value directly proportional to the determined acceleration. The second, parallel to the first, signal processing circuit includes two indicators 17 and 18, fixing the magnitude and sign of the output emf

Hall sensors, divider 19 and analog block 20 and performs the following conversions:

 ypH, l ± ypHrsinif

9 JpHj- fyf Hrcosi /

&

tgi /

The uncertainty associated with the uncertainty tg p (/ three changes of 0-360 - (/ + fJ) J, is excluded when taking into account the signs of the output signals, since in the first quadrant the values of U and U are positive, in the second - U is positive, U2 negative, in the third - U, and U is negative, in the fourth - U, negative, U is positive. Consequently, the simultaneous recording of + H sirMp, ± Hrcos if values and their processing allow us to uniquely determine the value and direction of the measured acceleration. the origin should be the direction perpendicular to the axis immetrii magnetic system in the plane of arrangement of one of the Hall sensors as when moving in a predetermined direction (x) values Hrcosif Hr, and HpSiiupO.

Claims (1)

Invention Formula A two-component acceleration sensor comprising a housing, an inertial mass on the suspension, and a displacement transducer, characterized in that, in order to improve the measurement accuracy, the displacement transducer made in the form of a magnetic system of four permanent magnets with pole pieces placed on the body and forming a magnetic quadrupole and two mutually perpendicular 5 Hall sensors mounted on an inertial mass placed in the center of the quadrupoles, with pole pieces made of a hyperbolic profile, the inertial mass is from 0 of the diamagnetic material, and the plates of the Hall sensor are placed at an angle of 45 to the axis of the permanent magnets. ag.1 20 1