SU732751A1 - String accelerometer - Google Patents

Description

(54) STRING ACCELEROMETER

The invention relates to instrumentation, measurement technology and can be used to measure the acceleration of the movement of an object. In the PMOD differential differential axometer, the action of the inertial force caused by acceleration measurements changes the tension of the strings 1. At the same time, the tension of one string increases, and the other decreases, which leads to a change in the natural frequencies of their vibrations. has a quadratic dependence on the change in tension, and, consequently, on the measured acceleration. The nonlinearity of the output characteristic is a significant drawback even in the differential scheme, in which, to reduce the error of nonlinearity, it is necessary to significantly limit the range of the tension change 2. The inertial mass associated with the strings, under the action of the input action, moves by elastic properties of the material of the string. The mass on the string is a high-pass-and-oscillating system, and in the case of,. if the string accelerometer is vibrated, it has a pronounced ansny peak. Usually, a damper is introduced to reduce the amplitude of oscillations of the inertial mass. However, small displacements of inertial mass in a string accelerometer practically exclude the possibility of using conventional dampers, for example air, to reduce the amplitude of mass oscillations. 4 The closest to the invention in its technical essence is string; a sensor comprising a housing with a clamped foam in it by means of string clamping elements, an inertial mass, an excitation and pick-up system for the oscillations of the string 3. The disadvantages of the string sensor are small displacements of the inertial mass determined by the elastic properties of the string material and limiting the use of known dampers string accelerometer for measurements with a high level of vibration noise; non-linearity of the dependence of the output characteristic relating the frequency of oscillation of the string with the input action. The aim of the invention is to improve the measurement accuracy by linearizing the dependence of the frequency

string oscillations from peremoz

To achieve this goal, holes are made in the inertial mass, by means of which it is placed on the inserted, rigidly fixed in the side walls of the case, the string being reinforced with perpendicular guides.

The drawing shows a diagram of a string accelerometer.

The string accelerometer includes a housing 1 in which guides are fixed, for example, two axes 2 and 3. The inertial mass 4 is compressed with double springs with reference springs 5. The string end is fixed to one end of the string 6 by means of an electric tape clamp 7 The second end of the string is fixed in the element clamp 8 of the case of the string accelerometer. The string is placed in the gap of the system 9 of excitation and removal of vibrations. The inertial mass has a cylindrical bore in which a piston H is placed, for example, an air damper. The movement of the inertial mass is limited by the stops 11 and 12.

The device works as follows.

 Under the action of a force, the inertial mass deviates from the equilibrium position by the value of d, and the length becomes equal to

i, v.

(one)

where .Q is the length of the string in the initial

the position of the inertial mass; the extension of the string from moving the inertial mass. Based on the connection of the string and the inertial mass, the elongation of the string is defined as the hypotenuse in the right-angled triangle, where one of the legs is a string, the length of which is, and the second is the displacement d of the inertial mass

  C + - 2) Substituting the expression (I) and the expression 2), we have

vS. "Y- -2

( )- WITH-

(3)

After the transformation, we get about D

 (1 +, 5.

("2 g, then expression (4) is written as

BUT

(five)

2nd,

Analyzing expression (5) we see that in the first part of the equality d – c 2, whence it follows that S & i.e. string elongation is less than the inertial mass displacement.

Elongation of the string with Hooke's law is equivalent to a change in the force F equal to

„ES о F -, 6,

(6)

V

where E is the modulus of elasticity of the material

strings;

S is the cross-sectional area of the string.

The change in the oscillation frequency of the strings C1 taking into account (5) we write in the form

-)

where c is the linear density of the material

. If-: strings;

 Y-- is the transform coefficient.

According to expression (7), the change in the frequency of oscillation of the string is proportional to the movement of the inertial mass.

Claims (2)

1. Seleznev V.P. Navigation devices. M., 1974, p.351-353. 2. Novitsky P, V. and others. Digital devices with frequency sensors. Energie, l., 1970. 3, USSR Copyright Certificate No. 299748, cl. G 01 L 1/10, 1968 (prototype). s fff UA 7 ///// 7} /// L fi