SU1185247A1 - Compensation pendulous accelerometer - Google Patents

Abstract

KOZHENSATSIONNYE PENDULAR ACCELEROMETER, comprising a case, a sensitive element fixed to it on an elastic suspension with electrically conductive surfaces, two fixed on the case on both sides of the sensitive element stationary electrodes, a pulse electronics unit connected to the sensitive element and stationary electrodes, characterized in that In order to improve accuracy, a voltage source and two additional electrodes are inserted in it, mounted on the housing of the PS, both sides of the sensing element and offset relative to the axis of the suspension, the voltage source being connected to one sensing element, and the other to two additional electrodes. (L

Description

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The invention relates to a measurement technique and can be used to measure linear accelerations in inertial navigation systems. ..

The purpose of the invention is to improve the accuracy of the accelerometer by compensating for the ultimate stiffness of the elastic suspension of the sensitive element.

Fig. 1 shows the construction of an accelerometer with a non-conductive sensitive element, for example, quartz in Fig. 2, section A-A in Fig. 1; on fig.Z - section bb in fig. G; FIG. 4 is a variant of the design with an electrically conductive sensitive element; FIG. 3 — section BB, FIG. four ; in fig. 6 - section G-Y in FIG. four

The accelerometer contains a central plate 1, a sensitive element 2 attached to the central plate through elastic beams 3. Electrically conductive layers 4 are sprayed onto flat surfaces of a non-electro-conductive sensitive element. Fixed plates 5 are located on both sides of the sensitive element. an electrically conductive layer 6 is printed on them. Sensitive element 2 and plates 5 form elements of an electrostatic angle sensor combined with a moment sensor a.

The central plate 1 is fixed with respect to the fixed plates 5 by means of gaskets 7 and 8. On the outer sides of the sub-plates there are elements of a pulsed electronics unit 9 connected electrically with; electrodes of fixed plate and sensitive element. The carrier element of the accelerometer design is the housing 10. A protrusion 11 is made on the sensitive element. Two additional electrodes 12 are located on either side of the projection connected to the voltage source of the electronic unit 9.

The device works as follows.

Under the action of acceleration on the sensitive element 2, the inertial force is balanced by the compensating force of the torque sensor through the sensing circuit. As an angle sensor combined with a capacitive-type torque sensor, the sensing element 2 with the electrically conductive layer 4 deposited on it and the fixed plates 5 with the electrically conductive layers 6 are used. The operation of these elements as an angle sensor and an axial sensor is divided in time and provided by a pulse unit electronics 9. At one of the time intervals, the electronics 9 determines the position of the sensitive element. In the next interval, the pulse unit 9 forms a voltage on the plates 2 and 5, creating a compensating force proportional to the deviation of the sensitive element from the equilibrium position. From the magnitude of this stress, the magnitude of the acceleration acting on the sensitive element is judged.

The presence of a static error in the angle of deflection of the sensitive element under the action of acceleration on it, the discrepancy between the equilibrium position of the sensitive element with the zero position of the angle sensor, the displacement and drift of the DC amplifier included in the electronics unit 9 create an additional force determined by the rigidity of the elastic beams 3 and introduces an error in the measurement of acceleration. In the device, the stiffness of the beams 3 is compensated by the protrusion 11 on the sensing element and two interconnected electrodes 12 connected to an additional voltage source included in the electronics unit 9. The electrodes 11 and 12 with an additional voltage source create negative rigidity. At a certain voltage of the additional source and a certain mutual arrangement of the electrodes 12 relative to the electrode 11, taking into account the displacements of the latter, this negative rigidity is almost linear and can be equal to the rigidity of the beams 3.

Indeed, the electrostatic force of attraction of the moving electrode .11 to one of the fixed electrodes 12 is equal to

.5 S; () and to another

,, U2, / (e,) S

where E is the dielectric constant of the medium between the accelerometer electrodes; 3 Sj - the area of the electrode 12; U is the voltage between the electrodes 1 1 and 1 2 v de, is the displacement of the electrode 11 from the neutral position, in which the distance between the electrodes 11 and 12 is equal to e The resulting force acting on the moving electrode 11 is determined by the expression., And, e , le, / (e, + le |) Therefore, by providing constructively that not more than a few microns, and e to be several tenths of a millimeter, we will have F (i.e. electrodes 11 and 12 with an additional source wives create

A-A

. 3

// 74 almost linear negative stiffness. When the accelerometer's sensitive element is deflected by an angle θ, the moment created by the resultant force F on arm f relative to the axis of suspension of the sensitive element is equal to M, (, / e .. Proceeding from the condition of stiffness compensation C, 3 M, C, hence. The additional power source should be equal to T | ee3 / (). Thus, a complete compensation of the stiffness of the beams of the elastic suspension of the accelerometer sensitive element is achieved.

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Claims (1)

COMPENSATING PENDULAR ACCELEROMETER, comprising a housing, a sensing element mounted thereon on an elastic suspension with electrically conductive surfaces, two fixed electrodes mounted on the housing on both sides of the sensing element, a pulse electronics unit connected to the sensing element and the fixed electrodes, characterized in that, in order to increase accuracy, a voltage source and two additional electrodes are introduced into it, mounted on the housing on both sides of the sensitive element and offset tnositelno suspension axis, whereby the voltage source is connected to one end of the sensing element, and the other - to the two additional electrodes. Tig!