About some problem for dynamically tuned gyroscope with flexible gimbal

I.V.Balabanov, T.V.Balabanova

National Technical University of Ukraine

"Kiev Polytechnic Institute"

37 Prospekt Pobedy, 03056, Kiev-56, Ukraine

G.M.Vinogradov, N.A.Temlyakov

Ramenskoye Instrument Design Bureau

2 Gurjev St., 140103, Ramenskoye, Moscow Region, Russia

 

In the present paper it is shown that elastic elements of the structure of a flexible gimbal of a dynamically tuned gyroscope of the GVK-18 type, in case of the rotor force acting along the gyro spin axis, undergo an axial deformation of the same type (tension or compression). An appropriate theoretical substantiation is given to explain the influence of axial force on functional angular stiffness of elastic elements of a variable cross-section. In order to obtain an approximate analytical solution, respective calculations have been carried out for an elastic element of a constant section showing that tensile force reduces its functional angular stiffness, whereas compressive force increases it.

The device GVK-18 is a dynamically tuned gyroscope (DTG) having a flexible gimbal assembled on the basis of a single-ring design concept. It is known that dynamic tuning is of great importance for proper operation of dynamically tuned gyros.

During the operation of GVK-18, it has been revealed that dynamic tuning of the device changes depending on the device orientation in the gravity field.љ In this case, the maximum difference of dynamic tuning frequencies occurs when the axis of proper rotation of the gyroscope is first directed vertically up and then vertically down.

Thus, the purpose of the given paper is to present calculation results showing the change in angular stiffness of the flexible gimbal of the GVK-18 device under the action of gravitational force causing the change in the frequency of dynamic tuning.

It should be noted that the value of the angular stiffness of the flexible gimbal of GVK‑18 about its measurement axes almost fully depends on angular stiffness of elastic elements of the gimbal, and the rotor weight exceeds substantially the weight of the flexible gimbal. Therefore in order to achieve the aim stated in this paper, it is necessary to calculate functional angular stiffness of elastic elements of GVK-18 changing under the action of the rotor weight.

When dealing with the structure of a flexible gimbal of DTG of the GVK-18 type, it should be noted that it consists of two "parallel"-connected structural parts ("internal" and "external") representing, in fact, two simple flexible gimbals, each including one inertial element . The forces of non-elastic nature acting from the side of rotor R in the direction of axis Ox₀ (the DTG spin axis) will essentially be balanced by elastic forces of elastic elements of the "internal" structural part of the gimbal whose longitudinal lines are parallel to axis Ox₀. In addition to that, the arrangement of elastic elements of the "internal" structural part of the gimbal and the diagram of their connection with the rotor, ring element and drive shaft, in case of the rotor force acting along the gyro spin axis Ox₀, cause a longitudinal deformation of all elastic elements that will be of the same type (tension or compression).