INTRODUCTION:-
In my schooldays, I played with a stick by adjusting it with my fingertip. To balance the stick, I made to regularly to change the area of my finger to keep stick vertically. The inverted pendulum is also the same in control and instrumentation. Moreover, the shift is limited to only in one way compared to the stick balancing by moving the hand up and down, right and left directions.
The balance of an open loop unstable system is determined by using an Inverted pendulum system. This is the most popular and widely used method in academic and research areas for demonstration and experimental propose.
The objective of this experiment to succeed step by step procedure to explain the inverted pendulum and its balancing using feedback control system. The main steps involved in this
1. Considering and working with QNET Rotary inverted pendulum trainer kit ,Elvis II board and its working. Convey the output captured in LABVIEW to excel and plot graphs.
2. Explain the MATLAB and simulink softwares and design the mathematical model of the open loop inverted pendulum model in MATLAB and simulink software backdrop.
3. Perform the experiment by simulating the inverted pendulum model is open loop and closed loop.
4. Take the generated simulation output and show the data in graphical formats.

2. Modeling of a Rotary Inverted Pendulum
2.1. FEATURES OF QNET ROTARY INVERTED PENDULUM
The above diagram shows the QNET Rotary Inverted pendulum kit. This kit has two major peripherals
1.QNET ROTOPENT
2.NI Elvis II
QNET ROTOPENT : QNET ROTOPENT is an assembly various parts listed below a.
DC motor b.
L- shaped arm c.
Pendulum d.
Two optical encoders

I ELVIS II contains of multiple components as listed below a.
Function generator b.
Digital multimeter c.
Ode analyser d.
Oscilloscope e.
Variable power supply f.
Other instruments
This is connected to PC using USB cable. This also has portable circuit board which helps user to construct circuits.
This QNET Rotary pendulum is a special servo system designed to understand and teach the basics of balancing of controlling of inverted pendulum.
It is uniquely designed to work in sync with ELVIS platform and system design platform & Development of environment LABVIEW software. This system can be constructed easily to understand different control techniques.
2.2. WORKING OFQNET ROTARY INVERTED PENDULUM KIT
1.
DC motor
2.
ARM angle encoder
3.
Metal chamber
4.
Rotary arm pivot
5.
Rotary arm
6.
Pendulum encoder
7.
Pendulum pivot
8.
Pendulum link
9.
Pendulum weight
10.
PCI connector to NI ELVIS
11.
QNET PWM/Encoder board
12.
24V QNET power jack
13.
Fuse
14.
+15V,-15V,5V LED’s
Figure 2 Inverted Pendulum kit

This inverted pendulum contains of a
. Direct drive direct current motor vertically seated in a frame made of solid aluminum.
. A pendulum is hanging at the end of L shaped arm on horizontal axis.
. The L shaped arm is connected to a motor shaft and swivels between ±180 0 .
The DC motor is driven by the Pulse width modulated amplifier, where the input voltage was a control variable and output variable is a pendulum angle and angular position of a DC motor which is measured by one ended rotary encoder.
2.3. OPERATION OF QNET ROTARY INVERTED PENDULUM
This experiment is performed to view, determine and understand the basics of inverted pendulum balance and control. By understanding how the controller in the kit balances and maintains the pendulum in vertical point.
The presentation of the operation of QNET Rotary inverted pendulum kit is done as explained below in step by step procedure.
. Establish the QNET Rotary inverted pendulum kit is connected computer with USB cable.
. PC, NI ELVIS II, and QNET is powered on.
. Executed the QNET ROTPEN Quick start .Vi downloaded from Blackboard
NI measurement & automation (NIMA) explorer window launched
. Selected the connected device from device dropdown list . This selections facilitates data flow from NI kit to NIMA explorer window.
. Choose the white arrow available in the top toolbar with left mouse button Virtual instrument is launched.
. At this point slowly taken the pendulum with hand to upright spot.When the pendulum reach vertical position controller activates automatically and started controlling the pendulum to maintain it in upright side, and removed the use of manual support.

Now the pendulum is vertically balanced with the help of controller.
Angle v/s Time and voltage v/s Time graphs are drawn in response the adjusting the pendulum in NIMA explorer window.
. Exported the plots to computer in jpeg type by using export option ready in graph context (RMB click) menu.

. As the experiment is finished, selected stop button to block the virtual instrument.
2.4. ROTARY INVERTED PENDULUM MODELLING IN SIMULINK SOFTWARE
The structural model of NI ROTAPEN kit is below. The component have restricted changes, it has two degrees of freedom and can be moved in two different axis .

. The arm can be moved freely about Y o
axis within +90 and -90 degrees.
. The angle of the arm is represented by
This value of rotation angle is considered positive when arm moves in clockwise direction, and
The value of the rotation angle is taken as negative when arm changes in anti clockwise direction.