RU1827659C - Meter of acceleration and vertical gradient of gravity force - Google Patents

Abstract

Usage: measuring technique for measuring a vertical gradient and accelerating gravity. SUMMARY OF THE INVENTION: a sensitive system contains only one load, which (the load) is equipped with a traverse, one end of which is rigidly fastened to the load through a support, and the other end is suspended on an elastic element in the form of threads or torsion bars, the load is equipped with a movement indicator, a main force sensor and an additional force sensor, the sensitive system is equipped with a device for changing places in height. 2 ill.

Description

The invention relates to a measurement technique for measuring a vertical gradient of gravitational acceleration Wzz and gravitational acceleration d.

The aim of the invention is to increase the accuracy of measuring the vertical gradient and to be able to measure the acceleration of gravity, i.e. expanding the functionality of the meter.

In FIG. 1 is a schematic diagram of the proposed vertical gradient and gravity acceleration meter.

Its sensitive system contains only one load, for example, in the form of a permanent magnet 1, a magnetic circuit 2, a pole piece 3, which is equipped with a beam 4. One end of the beam 4 through the support 5 is rigidly connected to the load, and the other end is suspended on an elastic element, for example, in the form of horizontally spaced threads or torsions 6,7, fixed in the housing 8. The load is equipped with a displacement sensor 9, for example, an inductive (or capacitive or raster photoelectric primary converter with a resolution equal to ten to microns. The output of the displacement sensor 9 is connected to the displacement indicator 10, for example, in the form of an ammeter in the case of an inductive displacement sensor. The load is equipped with a main force sensor in the form of a permanent magnet 1, magnetic core 2, pole piece 3 and winding 11 and an additional force sensor in in the form of a permanent magnet 1, a magnetic circuit 2, a pole piece 3 and a winding 12. The windings 11.12 are connected to a constant current source 13 through devices for changing the supply current (or voltage), for example, in the form of variable resistance 14, 15 and a contact switch 16, 17. A current indicator 18 is installed in the winding circuit 12, the value of which determines Wzz (the pointer can be calibrated immediately in the dimension WZz). The load is also suspended on a spring

cl

with

00

Yu

Vj

about sl u

19 provided with a vertical displacement device of its upper end (the device is not shown in the drawing).

The housing 8 with a pin 20 using the support 21 is installed in the rod 22 of the device for changing the position of the housing 8 with a sensitive height system. The rod 22 is mounted on a stand 25 using a pin 23 and a support 24. A counterweight 26 is provided on the rod 22 (to balance the housing 8 with the sensing system).

By turning the rod 22, the housing 8 with the sensitive system can change its height position. Cages (not shown) are provided for locking the bar 22 with the casing 8 in the upper and lower positions.

The displacement sensor 9 in the manufacture (assembly) of the meter is set to the zero position (zero indication of the displacement indicator 10) with the horizontal position of the yoke 4.

In the operating position, the measuring axis of the sensitive system (axis of symmetry of the load) is located in the direction of gravity.

The housing 8 is sealed and can be evacuated. To attenuate the oscillations of the load, damping is provided (for example, due to the corresponding gaps between the magnetic core 2, the tip 3 and the frame 27 of the windings 11, 12 in the case of an non-vacuum housing 8).

The device for changing places along the height of the sensitive system can have another design, for example, moving the housing 8 manually from the platform at one height to the platform of another height and

other

In the considered example of the schematic diagram of the meter, a permanent magnet with a magnetic circuit is used as a load, or vice versa, a magnetic circuit with a magnet can be fixed to the housing, and the frame 26 with coils 11, 12 can be suspended as a load.

Instead of the spring 19, another elastic element can be used, for example, in the form of a float protruding above the surface of the liquid, when the Archimedean force and other elastic forces are used as the elastic force. The elastic element of the traverse 4 suspension can also be made in the form of a flat spring 28 (see figure 2), one end of which is bonded to the traverse 4, and the other end to the housing 8.

The proposed meter works as follows.

The measurement is determined by the algorithmic method in two measurement steps.

The first beat. The contact switch 16 is closed, the contact switch 17 is open, the housing 8 with the sensitive system is installed in the upper position.

By changing the supply voltage of the winding 11 of the main force sensor with resistance 14, the zero indication of the movement indicator 10 is set. The final zero value can be set by moving the upper end of the spring 19 with a micrometer screw (not shown).

As a result, the gravity of the load is balanced by the force of the main force sensor and

forces of mechanical springs

mg FAci + + cs,

0)

where m is the mass of the cargo;

g is the acceleration of gravity at the level of the center of gravity of the load in the upper position;

RdS1 - force of the main force sensor; t - total angular stiffness of the threads

6.7;

p is the angle of rotation of the beam 4 from the neutral position;

I is the distance from the axis of symmetry of the load to threads 6, 7 (see drawing);

C is the linear stiffness of the spring 19; s is the tensile value of spring 19.

35

p arctg -,

(2)

where z is the deviation of the load from the calculated zero position of the load (i.e., the deviation from the ideal zero by pointer 10). Since z «l, we can put with sufficient accuracy

and from (1) and (3) we have

mg FACi + -J2- + CS,,

(3)

(4) (5)

5

where B is the magnetic induction in the gap between the pole piece 3 and the magnetic circuit 2;

LI is the length of the conductor of the winding 11;

and - current in the winding 11.

The second beat. Housing 8 with a sensitive system is installed in the lower position. Acceleration acts in the center of mass of the load

g + WzZH,

(6)

where H is the height distance between the upper and lower positions of the load.

Under the influence of force

m (g + WzzH)

the load is moving, the z value is changing.

We close the contact switch 17 and change the magnitude of the supply voltage of the winding 12 of the additional force sensor with resistance 15, set the zero indication of the displacement indicator 10, and the force Rds2 of the additional force sensor is applied to the load. As a result, we have

By measuring the current in the winding 12 of the additional force sensor with a meter 18 calibrated in accordance with formula (11) and formula (8), we obtain the values of WZz.

The relative measurement error according to (11) is equal to (5)

P

Wtz

 G + 1r. + 3,

(12)

Where

fifteen

(thirteen)

m (g + WzzH) FAci + FAc2 + - & (z + Az) +

+ c (s + Az), (7)

where Rdc2 is the strength of the additional force sensor;

Az is the value of the error of setting the zero position of the load in the second measure relative to the position of the first measure,

,

(8)

where is the length of the conductor of the winding 12;

i2 is the current in the winding 12.

According to two measurement steps from (4) and (7) we have

Fgc2

Hm

+ | + s

Az

Ntg

(9)

The second term due to the uncertainty of Az gives the instrumental error AWZZ from Az

A,.,, AZ

Awzzi b + s w

(10)

Asked by real values, 3 kg, 5 m, gsm2 / s2 / 2, s. 256, line 22 from below /,, n / m (i.e., spring 19 may be absent),, 1 m, D, 0-0.1 MK 10 fi-10 7M we get

AWZ2 (1.33-, 67) Oe

whence we see that AWZz can be provided sufficiently small and from (9) to determine WZz by the formula

Wzz

Fgc2

Hm

(eleven)

where A RDS2 is the absolute measurement error of FAc2;

AN is the absolute error in keeping N.

Am - change in the mass of the load (equal to O, because the load is one and its mass is unchanged).

From (11), (12) we see that the methodological measurement error from g, unlike the prototype, is absent. Since by (8)

.

0

then; i

AB

AT

+

AZ2

Z2

+

Ai2

12

(14)

5

0

5

0

5

and J / 1 is determined only by the accuracy of measurement 2.

For ni, tft, 3 of order 10, we obtain from (12) the value of d) of the same order, i.e. at E

AWZ2, 04 Oe

For the prototype, as described above in this description and in the known value of 773 (and other parameters) to ensure accuracy of 5 Oe, it is necessary to maintain within 10, i.e. 5 times stiffer and so the accuracy of the proposed gradiometer will be higher by 5-6 orders of magnitude in comparison with the prototype.

The same meter allows you to measure and.

In particular, for relative measurements of g, it is sufficient in the starting point to configure the meter according to the first measurement step (in the upper or lower position of the sensitive system) and with unchanged BiLi, And determine Hell, transfer the meter to definable observation points and perform a second clock cycle according to RDS2, t .e. by iz.

It is quite obvious that by applying compensation feedback with the integrating links of the displacement transducer to the force sensors, the measurement process of the proposed meter can be automated.

Thus, in comparison with the prototype, the accuracy of measuring Wzz by the proposed meter is not less than 5-6 orders of magnitude higher, and the meter can measure q.

Claims (1)

SUMMARY OF THE INVENTION An accelerometer and a vertical gravity gradient meter comprising a sensing system including loads enclosed in a housing and a recording system, characterized in that, for the purpose of 0 increasing the accuracy of measurements and expanding the functionality, the sensitive system contains an OAVIH load attached to the body by means of a spring, while the load is rigidly fastened to one end of the beam, the other end of which is suspended on an elastic element, the load is equipped with a displacement sensor, main and additional force sensors, the windings of which are connected to a constant current source, the registration system is made in the form of a current meter included in the winding circuit of an additional force sensor, and the case of the sensitive system We are equipped with a device for changing places in height, five i