This document discusses active vibration control of antenna reflectors using piezoelectric materials as sensors and actuators. Piezoelectric sensors detect vibrations in the antenna structure and piezoelectric actuators apply counteracting forces to reduce vibrations. The system is tested on a cantilever beam model. Simulation results show that the controlled system experiences significantly less vibration than the uncontrolled system. The method provides effective vibration reduction for precision antenna structures.

1. Active Vibration Control of
Antenna Reflector
SHUBHAM.G.M.,
M.TECH SENSOR
SYSTEM TECHNLOGY
VIT UNIVERSITY,
VELLORE -632014.
Shubham.gangadhar2016@vit
student ac.in
A.MADHUSUDANAN
M.TECH SENSOR
SYSTEM TECHNLOGY
VIT UNIVERSITY,
VELLORE -632014.
a.madhusudanan2016@vit
student.ac.in
S.PRABHAKARAN
M.TECH SENSOR
SYSTEM TECHNLOGY
VIT UNIVERSITY,
VELLORE -632014
Prabhakaran.s2016@vit
student.ac.in.
GUIDE:
DR.Z.C.ALEX
PROFESSOR
DEPT OF MEMS AND
SENSORS,
VIT UNIVERSITY,
VELLORE -632014
zachariahcalex.
@vit.ac.in
Abstract—Vibration control is the ubiquitous operation found in
wide variety of application in various fields, especially in mechanical
structures. Many times unwanted vibrations are propagated
through the structures in mechanical fields. The vibration control
of an active smart structure of antenna reflector is employed
through a set of sensor and actuator connected by a feedback loop.
Here the piezoelectric material is attached to the active structure for
effective vibration reduction. Simulation results show the difference
between controlled and uncontrolled vibration of the system.
Key Words—PZT, Lab VIEW, sensor, actuator, MYDAQ.
I. INTRODUCTION
This paper is about controlling the active vibration
Occurs in space antenna reflector.
Vibrations occur in various field of applications. These vibrations
may be desirable or disturbing. This paper studies about vibration
detection and methods to prevent them. Vibration is a movement
of particle or system connected with devices dispersed around the
balanced position.
Most vibrations are unavoidable in machines and equipment due
to overload, bearing loads, creating comfortless for people
travelling in vehicles and absorption of energy from system.
Surface precision for antenna reflector is important and even
small distortion may reduce the performance. The abrupt
vibrations causes bending of antenna structure.
To develop an active structure needed sensors, actuators and data
acquiring machines embedded with antenna reflector. The unique
feature of active structures is that the actuators and sensors are
frequently separated with a high degree of isolation inside the
structure that makes a separate modelling impossible.
Although several research found in the active vibration control of
beams, plates but the examination on vibration control of antenna
reflector is limited.
Active vibration control is the application of force in equal and
opposite direction to forces imposed by external vibration. An
active vibration control reliable on the use actuator. The actuator
provides a force to the system. The actuator force compensate the
vibration force in the system. Piezoelectric materials will
elongate when an electric field is applied in a fixed direction. In
Alter, when a deformation is applied to a piezoelectric material
with an external force, an electric potential will be developed. In
this manner the piezoelectric material can be used both a structural
sensor and as an actuator.
Piezoelectric materials are anisotropic in nature. Applied
deformations in the direction Perpendicular to the poling axis
cause an electric field in poling axis due to the mechanical
coupling.
When building structure, piezoelectric materials bonded to the
structure in a uniform manner along with that both materials must
have electrical contact on each side of the material. Surface
bonding for piezoelectric actuators
is better access for fabrication, easier inspection, and less
maintenance.
II. PROPOSED SYSTEM
In the proposed system Space Antenna Reflector is
incorporated with the smart structure. Smart structures consists
of sensor, actuator. Piezoelectric used as actuator in order to
generate counter balance the free vibrations the structure of
antenna reflector is mathematically modelled and analyzed using
Lab VIEW software.
Two waves with equal amplitude and 180 degree phase shift
add together resulting in a cancelling of overall amplitude. Fig 1
refers to the concept of vibration control.
Fig 1: Concept of vibration control
The Transfer Function for a host structure is given by:
Wn2
---------------------------- (1)
s2
+ 2§Wn s+ Wn2

2. Wn : Resonance Frequency
§ : Damping coefficient
In the Frequency in HZ =537 and Damping co: = .5
Transfer function is follows :
1.138e007 (2)
----------------------------------
s^2 + 3374 s + 1.138e007
Fig 2: Block diagram of proposed system
A cantilever beam (steel scale) is used as host structure. The
piezoelectric material is used as sensor and actuator. The
cantilever boundary condition is generated by clamping edge
of beam using C-clamp. The free vibrations are set in the
smart cantilever beam by providing initial displacement in
the vertical direction. Fig 3 refers to the experimental setup
of the system. Piezoelectric sensor generates charge when it
is subjected to mechanical strain. The amplitude and
frequency depends on the mechanical deformation. The
analog voltage signal is then converted into digital signal by
feed into MYDAQ (National Instruments).By analyzing the
sensor signal, the counter signal is generated using lab view
and feed into actuator in the beam using MYDAQ. Vibration
on beam gets suppressed. Fig 2 refers the entire process of
system through block diagram representation.
Fig 3: Experimental setup
III.) COMPONENTS USED
A.)Piezoelectric Sensor
Piezoelectric sensors works on the principle that when a
piezoelectric material is stressed electric charge is generated and
it results in deformation. These sensors are highly sensitive, high
frequency noise rejection and provides superior signal-to-noise
ratio. Piezo film has an advantage that it is approximately ten times
as sensitive as semi-conducting gauges and it is over 300 times as
sensitive as resistance gauges. When the sensors are bonded to
another material it causes the sensor to disfigure with the base
structure. By measuring the voltage across its electrodes the
deformation of the sensor can be measured. In this case the sensor
is bonded to the
surface of the beam using adhesive.
B.) Piezoelectric Actuator
The piezoelectric actuator is a device which is based on the counter
piezoelectric effect. It creates a
displacement when a voltage is applied to it. PZT actuator is a
controllable and micro-displacement actuator which is operated by
electric field. PZT actuator consists of a very high-speed response,
a relatively light mass and a little quantity of heat. As the
performance of PZT actuator is excellent, thus it has a considerable
potential in the field of active control.
By consuming electrical energy during movement, this Piezo
effect converts electrical energy into motion. There is no power
consumption in Static operation and even holding of heavy loads.
The PZT actuators produce the quickest response time available
which is in microsecond time constants. The PZT actuators do not
have gears and rotating shafts. Its displacement is traced from solid
state dynamics which shows no wear and tear.
C.) Data Acquisition Card-NI MY DAQ
NI myDAQ is a data acquisition (DAQ) device that provides
measure and analyze live signals anywhere, anytime. This
hardware with eight ready-to-run software-defined instruments,
including a FG, CRO, and DMM. NI myDAQ includes two analog
inputs and two analog outputs at 200 kS/s and 16 bits. It is pocket-
size, portable, and completely USB-powered. NI ELVISmx is the
driver software that supports NI myDAQ. NI ELVISmx uses Lab
VIEW based software instruments to control the NI myDAQ
device, providing the functionality of lab instruments.
IV.) RESULTS
Here the data acquisition card acquires the signal from Piezo
sensor and display in the front panel in Lab View. Using one of
the graphical programming functions in lab view the actuator
signal is generator and given to Piezo actuator. Fig 4 refers to
simulated results of sensor and actuator.
Fig 4: Simulated results of sensor and actuator

3. The results shows that reduction in vibration amplitude in
controlled compared to uncontrolled is considerable. Fig 5
shows the comparison between controlled and uncontrolled
vibration.
Fig 5: comparison between uncontrolled and controlled
vibration.
V.) ADVANTAGES
 This type of active control provide features for
structural vibrations control.
 The dynamics of sensors and actuators permit wide
range of frequency control.
 Piezoelectric transducers provide high frequency
response, high transient response and high output.
 The piezoelectric actuator has low power
consumption, fast expansion and no wear and tear.
 The efficiency of the system can be increased.
VI.) CONCLUSION
Using the procedure as described above, the vibration controller
was implemented on the system. A cantilever beam was made to
vibrate and its vibrations were measured using a piezoelectric
sensor and a counter force vibrations were developed using the
piezoelectric actuator which is given to the cantilever beam in
order to suppress the vibrations. Several experiments were
conducted to suppress the Vibration response using various
vibration levels and the results were simulated.
VII.) FUTURE SCOPE
Results from this experiment can be further improved. Further
focus will be the creation of better controllers through more
accurate models. As the experiment of active vibration controller
has come to a conclusion, various opportunities for expansion
have been identified. This experiment paves way into many
applications of aerospace and structural engineering. The
obstacle vibrations in the following airplane wings, helicopter
propellers, or any type of slender beam can be overcome in the
near future.
VIII.) ACKNOWLEDGMENT
We are thankful to our guide DR.Z.C.Alex
(Professor, DEPT OF MEMS and Sensors) for his
valuable guidance, encouragement and co-operation
throughout the project.
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