VIBRATION SENSING AND CONTROL FOR A CANTILEVER BEAM USING LABVIEW

Table of contents

Introduction Material Specifications Active and passive vibrations Experimental Setup PD Controller Experimental Results Observations Conclusion and recommendation References

Introduction

Material specification and instruments used

1. Dimension length- 27cm Breadth- 2.5cm Height- .07cm2. Material used- Mild Steel3. Software Used-Lab view

Active vibration control is defined as a technique in which the vibration of a structure is reduced or controlled by applying counter force to the structure that is approximately out of phase but equal in amplitude to the original vibration.

Techniques like the use of spring, dampers and pads are known as passive vibrations controlled.

Active and passive vibration

Experimental setup

Data acquisition system

Soldered PZT crystals

Basic Outline and Experimental setup

Lab view code

A PID controller is a control loop feedback mechanism (controller) extensively used in control systems.

What it does?? It calculates an "error" value as the

difference between a measured process variable and a desired set point which is given as input initially. It attempts to minimize the error by adjusting the process control inputs.

Theory behind PID controller

Proportional it depends on the present error Integral it depends on the accumulation of past

errors Derivative it is a prediction of future errors which is

based on current rate of change.

Parameters involved in PID

How PID affects the system

The effect of increasing each of controller parameters kp, ki and kd.

Typical steps for designing a PID controller are

1. Determine what characteristics of the system needs to be improved.

2. Use KP to decrease the rise time.3. Use KD to reduce the overshoot and settling

time.

This works in many cases, but what would be a good starting point? What if the first parameters we choose are totally crappy? Can we find a good set of initial parameters easily and quickly?

How do we use this table??

Experimental Results

Output by giving an impulse

Damping frequency = 50.24 rad/secNatural frequency = 50.26rad/secDamping ratio = 0.019Settling time = 4.188 sec Rise time = 0.015 sec

Input signal (Black wave) as well as output signal from controller (red wave)

Kp=1Kd=0.001

Kp=1Kd=.007

Following parameters are obtained Damping frequency = 50.24 rad/sec

Natural frequency = 50.26rad/secDamping ratio = 0.019Settling time = 4.188 sec Rise time = 0.015 sec

During controller design, the proportional

gain was set to 1. Increasing the Proportional gain to more than 1 increase the amplitude of the output signal.

Observations

Proportional Derivative (PD) controller can be used to control the vibrations.

we were unable to actuate the cantilever beam because the output signals produced by the controller were too weak to produce mechanical vibrations and hence cannot be implemented without an amplifier, nevertheless we observed the output signals on Labview

In order to accomplish it we need some amplifier to amplify the actuation given by PZT crystal

Conclusions

Block Diagram

K. B. Waghulde et al. /International Journal of Engineering and Technology Vol.2(4), 2010, 259-262.

Journal of Vibration and Control March 2012 vol. 18 no. 3 366-372.

http://www.kyu.edu.tw/93/epaperv6/93-033.pdf Wikipedia – The free encyclopaedia.. National Instruments (NI) manual. Tutorials on Controller design by National

Instruments (NI).

Reference

Thank You