A multi-layer electro elastic drive is used promising for micro and nano robotics in the micro and nano displacement.1−8 This drive based on the piezoelectric or electrostriction effects.9s−19 A multi-layer electro elastic drive of robotics is applied in adaptive optics of compound telescope, scanning microscopy, micro surgery, interferometry, nano pump, nano stabilization and nanotechnology.20−53 The deformations of a multi-layer drive are described with the matrix equation. Its parametric model, scheme and functions are obtained by using of mathematical physics method.
Parametric model
The parametric model6−53 of multi-layer piezo actuator with the voltage or current controlled are determined using the equation of inverse piezo effect in the form at the control of voltage
at the control of current
here
,
,
,
,
,
,
,
are the relative deformation, the strength of electric field, the electric induction, the strength of mechanic field, the piezo module, the piezo constant, the elastic compliances at
and at
, and
are the indexes.
The equation of the direct piezo effect has the form6−53
here
is the dielectric constants at
, k is the index
Then the electroelasticity equation of a multi-layer drive6−53 has the form
here
is control parameter at the control of voltage and the control of current.
A multi-layer drive consist from the piezo layers connected the series mechanically and the parallel electrically [6 − 44]. We have the system of equations for T-form quadripole of k piezo layer
where
,
,
,
,
,
,
,
,
are the resistances of quadripole k piezo layer, the transform parameter, the thickness, the coefficient wave propagation, the Laplace transform of the forces at the input and output ends of k piezo layer, the transforms of the displacements at input and output ends of k piezo layer.
The system of the equations for k piezo layer has the form
This system is founded in the matrix form
The equation of forces at the boundary between two layers is obtained in the form
For a multi-layer electro elastic drive with n layers and l length its system has the matrix form
then
The equations of forces a multi-layer drive we have in the form
at
at
The transform of its force causes deformation has the equation in the form
Then the parametric model and scheme on Figure 1 of a multi-layer electro elastic drive are obtained in the form
Figure 1 Parametric scheme multi layer electro elastic drive.
here
,
,
,
,
,
.
The matrix function of a multi-layer drive has the form
then
,
The functions of a multi-layer drive are determined
The function of the multi-layer longitudinal piezo drive with one fixed face is determined at the elastic-inertial load and the control of voltage in the form
Its transient response has the form
,
,
For the multi-layer longitudinal PZT drive at
=60 V,
= 4∙10-10 m/V, n= 8, M= 1 kg,
= 5.8∙107 N/m,
= 0.6∙107 N/m its parameters
= 174 nm and
= 1.25∙10-4 s are obtained with error 10%.