SU1492290A1 - Method and apparatus for measuring acceleration - Google Patents

Abstract

The invention relates to a measurement technique and can be used to determine the motion parameters of various objects. The aim of the invention is to increase the sensitivity and thermal stability of a device for measuring accelerations. The device comprises a bridge, the two arms of which comprise capacitive displacement sensors 2 and 3 and inductive elements 4 and 5. The bridge is driven by a sinusoidal voltage generator 1, tuned to resonance with one of the branches of the bridge. In the device, tuning is provided by positive feedback through one of the arms of the bridge. A voltage proportional to the acceleration is removed from the bridge diagonal to the differential amplifier 10. The thermal stability of the device is achieved by using piezoquartz resonators as inductive elements 4 and 5. 1 il.

Description

one

(21) 4205278 / 2A-10

(22) 03/04/87

(46) 07.07.89.BUL Number 25

(71) Leningrad State University

(72) B.I. Yevnevich, V.M. Krkko and N.G.Semenova

(53) 531.768 (088.8)

(56) USSR Copyright Certificate No. 901914, cl. G 01 P 15/08, 1980.

Dubovsky V.B. Measurement of low frequency accelerations. - M .: Science. 198I, p. 79.

(54) METHOD OF MEASUREMENT OF ACCELERATION AND DEVICE FOR ITS IMPLEMENTATION

(57) The invention relates to measurement technology and can be used to determine the motion parameters of various objects. Purpose

of the invention is the twisting of the sensitivity and thermal stability of a batch; Measurements for measuring accelerations. The device contains a bridge, the two arms of which comprise capacitive displacement sensors 2 and 3 and inductive elements 4 and 5. The bridge is excited by a sinusoidal voltage generator 1 tuned to resonance with one of the branches of the bridge. In the device, tuning is provided by positive feedback through one of the arms of the bridge. The voltage proportional to the acceleration is removed from the diagonal of the bridge to the differential amplifier 10. The thermal stability of the device is achieved by using piezo-quartz resonators as inductive elements 4 and 5. 2 sec. and I zp f-ly, I ill.

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The invention relates to a measurement technique and can be used to determine the motion parameters of various objects.

The purpose of the invention is to increase the sensitivity and thermal stability when measuring accelerations.

The drawing shows a diagram of a device implementing a method of measuring accelerations.

The device contains a generator of sinusoidal voltage I, a bridge, the two arms of which comprise successive resonant circuits consisting of capacitive displacement sensors 2 and 3, inductive elements 4 and 5, and resistors 6 and 7. Two other arms of the bridge form resistors 8 and 9. I sinusoidal voltage connected to the output of the diagonal of the bridge, denoted by the letters A and B. To the resistor 8 is connected to the input of the generator 1 so as to provide positive feedback of the generator through the branch of the bridge containing the capacitive sensor 2, ind element 4 and resistors 6 and 8 are active. The voltage of the bridge unbalance is taken from the diagonal D-E to the input of the differential amplifier 10.

Capacitive sensors 2 and 3 displacements can be made in the form of a differential capacitor with a common plate.

Acceleration measurements are made as follows.

In the absence of acceleration of the capacitive sensors 2 and 3, the displacements are equal to each other and the voltage in the diagonal D-F is zero.

Under the action of accelerating the capacitance of the capacitive sensors 2 and 3 are changed so that one of them increases, and the other decreases. The frequency of the generator 1 sinusoidal voltage is set so that it coincides with the natural frequency of the oscillatory circuit of one of the branches of the bridge, consisting of a capacitive sensor 2, an inductive element 4 of resistors 6 and 8. In the device, tuning the oscillator 1 into resonance with an oscillating circuit ensures positive feedback current oscillatory circuit through the resistor 8.

Another branch of the bridge is on the slope of a resonant frequency

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tests. Such a second circuit detuning along with unbalance of the bridge from changes in the capacitances of the capacitive sensors 2 and 3 provides a higher voltage of the unbalance of the bridge, which is characterized by a lower measured acceleration value. This voltage is amplified by the differential amplifier 10. For the case that the capacitances of the capacitive sensors 2 and 3 are equal and their changes under the action of accelerating the unbalance voltage of the bridge in the diagonal D-E, is determined by the expression

LU L, JQ- |.

where jjU is the voltage unbalance in the diagonal of mos: ta;

and - voltage at the output of a sinusoidal voltage generator;

O is the Q factor of the serial resonant circuit;

C is the capacity of each arm of the displacement sensor;

LS - the change in capacity under the action of acceleration.

In the device, the frequency instability of the generator does not affect the sensitivity of the device, since the frequency of generator 1 is determined by the parameters of one of the branches of the bridge, ensuring its operation in the resonance mode.

The use of piezo-quartz resonators with high temperature stability as inductive elements 4 and 5 ensures high thermal stability of the entire device.

Claims (3)

1. A method of measuring accelerations, implies that excite a bridge with two capacitive displacement sensors in its arms with sinusoidal voltage and measure the unbalance voltage of the bridge, characterized in that, in order to increase the sensitivity, the frequency of the sinusoidal voltage is set equal to the resonant frequency one of the branches of the bridge. 2. A device for measuring accelerations, containing a bridge with two capacitive sensors and connected in series with them inductive elements in the two arms of the bridge and resistors in two its other arms, a sinusoidal voltage generator connected by its output to one of the bridge diagonals and a measurer the bridal balance of the bridge connected to its other diagonal, characterized in that One of the bridge arms with a resistor is connected to the input of a sinusoidal voltage generator to form a positive feedback. 3. The device according to claim 2, about t and which is the fact that, in order to increase thermal stability, piezoquartz resonators are used as inductive elements.