| 其他摘要 | Piezoelectric ceramic is a functional material which can make a conversion
between mechanical energy and electrical energy. Mechanical stresses in the
piezoelectric materials produce measurable electric charge, which is referred to the
direct piezoelectric effect. Vice verse, mechanical strains are geneeated in response to
an applied electric field and this is called the inverse piezoelectric effect. Piezoelectric
actuator is a precise positioning mechanism which is utilized the inverse piezoelectric
effect.
Piezoelectric actuator has been widely used in the fields of micro and nano
positioning applications such as aerospace, data storage, optical communication,
ultra-precision machining, biological engineering and semiconductor technology, due
to the excellent advantages of small volume, fast response time, extremely fine
resolution, large mechanical force and noiseless. In this paper, the actuator is applied
in cavity ring-down spectroscopy (CRDS), In the detection of trace gas in atmosphere
by CRDS, the precision and stability of length of optical cavity have a great influence
on the final result, so it is necessary to control the length of the cavity precisely.
According to system requirements, the positioning accuracy of the cavity length is
3nm.
This paper studies the positioning principle and driving method of piezoelectric actuator, design and construct a control system of piezoelectric actuator based on
stm32. In the system, a digital-analog conversion unit, a power amplifier unit, a
displacement detection unit and a analog-digital conversion unit have been included,
the designed system has advantages such as small size,easy control,and versatility.
The testing results show that outputs of the control system have a good performance,
and fit the design requirement well.
Besides, piezoelectric actuator suffers from the inherent hysteresis effect because of
loss phenomena taking place inside piezoelectric materials, the hysteresis effect
exhibits complex nonlinear characterisitics, which usually introduces descent of
accuracy or oscillation and even instability. In aim to reduce the influence of
hysteresis nonlinear, this paper studies the theory and methodology of hysteresis
modeling, nonlinear compensation and control, a Prandtl-Ishlinskii (PI) model has
been proposed to describe the hysteresis loop of actuator, and radient descent method
has been utilized to identify the model parameters, through the simulation of
Matlab/Simulink, we can found that the model output and the actual data are well
fitted. According to the PI model, a compounding control method with feedforward
compensation based on inverse model has been designed, an inverse hysteresis
compensator is developed to cancelate hysteresis in the feedforward loop, and a PID
controller has been designed as a feedback controller to minimize the tracking errors.
The simulation results demonstrate the effectiveness of the proposed control method.
Finally, an experiment has been carried out, and the results show that the average
positioning error is 10.5nm, the main reasons why there existing a gap when
compared to the expected are the drawback of circuit designing and PCB layout, the
test environment also have an influence on the results. |
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