In the thesis, a new piezoelectric gravimeter of the automated aviation gravimetric
system (AGS) is explored. The author analysed literary sources in the field of modern
aviation gravimetry, determined the methods and means for determining the gravity
acceleration by various gravimeters, developed a constructive scheme.
The ideology of the development of a dual-channel piezoelectric gravimeter of the
AGS is substantiated. The modern precision requirements for AGS gravimeters are
determined. A new dual-channel piezoelectric gravimeter of the AGS, the features of
which make it possible to overcome all the abovementioned disadvantages of the existing
AGS gravimeters, are proposed.
An overview of scientific works on piezoelectric transducers is given and a
functional diagram of a new dual-channel aviation piezoelectric gravimeter is developed.
The mathematical model of a dual-channel piezoelectric gravimeter has been developed
and its basic design and electrical parameters are calculated. Methods for placing PE in
the structure of the dual-channel PG have been considered and their comparative
characteristics are completed, their advantages and disadvantages are determined. The
following way of placing the PE has been chosen – off-centre and attached by a screw.
The analysis of the main types of piezoelectric materials (quartz, lithium niobate,
tourmaline, Rochelle salt, lithium sulfate, ammonium dihydrogen phosphate, ceramics)
for the SE of a new dual-channel PG has been carried out. Lithium niobate was chosen as
the material for the SE of a new dual-channel PG. Lithium niobate has a high resistance
to changes in external temperatures and pressures, a high coefficient of electromechanical
coupling and stable piezoelectric properties, which is important directly for the dualchannel
PG design.
The problem of filtering the output signal of a dual-channel PG from highfrequency
interference was solved by using the piezoelectric element of a new dualchannel
PG both as a SE and a low-frequency filter. Methods of the structural
achievement of PG natural frequency of 0.1 rad/s were proposed. The optimal one has
been chosen by increasing the input resistance of the operational amplifier.
The main characteristics of the dual-channel PG were determined. They are: the
operating range of the GE, the operating frequency range, the temperature dependence of
the piezoelectric parameters of the PE, and others.
Methodological errors of automated AGS were analysed. The main errors of a new
PG have been identified and the ways to reduce them are proposed.
A mathematical model of an aviation gravimetric system for measuring GE
anomalies has been developed, which differs from the known ones by additional
corrections, the error from neglect of which is unacceptably large (3.67 mGal). The
equations of motion were obtained, the block diagrams of all the main components of the
AGS were determined: the systems of stabilization, navigation and determination of GE
anomalies.
The block diagram of the GE signal transformation in the piezoelectric element of
the new dual-channel PG was studied and described, and a method for input voltage
compensation by introducing negative feedback based on the inverse piezoelectric effect
was proposed. The transmission coefficient of PE made of lithium niobate was
determined, and it is 1.682.
The permissible error of the dual-channel PG sensitivity axis stabilization to the
vertical position of 1 arcmins for an accuracy of 0,5 mGal was calculated and ways of its
reduction by using the methods of the high-precision setting of the dual-channel PG
sensitivity axis are proposed.
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The composition and structure of dual-channel PG errors were identified, and the
main ones were studied and calculated. Instrumental measurement error did not exceed
0.1 mGal. Errors caused by noise of various origins, the method of attachment to the base
and the offset of the zero point can be completely eliminated with the help of design
features of a dual-channel PG.
With the help of a computer the influence of frequencies and amplitudes of
perturbing vibrational accelerations for the most unfavourable resonant cases was
studied: = 0, = 20, = 30, 2 = 0, 3 = 0, where 0 is the frequency of dualchannel
PG natural oscillations, is the perturbation frequency.
Digital simulation of the influence on the dual-channel PG perturbation parameters,
as well as on its own parameters confirms the main advantage of dual-channel PG over
known gravimeters – its higher accuracy (1 mGal).
Possibilities of using the neural network approach in problems of algorithms
development of AGS functioning with a new dual-channel PG were considered.
Experimental studies of AGS with dual-channel PG using neural networks are performed.
An experimental facility to study the main characteristics of dual-channel PG is created
and the expediency of its application as a part of AGS is substantiated.
