DIGITAL CONTROLLER DESIGN BY POLE PLACEMENT FOR IBM LOTUS DOMINO EMAIL SERVER

International Journal of Innovative Science and Modern Engineering (IJISME)

ISSN: 2319-6386, Volume-3 Issue-3, February 2015

Published By:

Blue Eyes Intelligence Engineering

& Sciences Publication

Retrieval Number: C0808023315/2015©BEIESP

DC Motor Speed Control using PID Controller in

Lab View

Pratap S Vikhe, Neelam Punjabi, Chandrakant B Kadu

Abstract- Proportional-Integral-Derivative (PID) control is the

most common control algorithm used in industry and has been

universally accepted in industrial control. One of the applications

used here is to control the speed of the DC motor. Controlling the

speed of a DC motors is very important as any small change can

lead to instability of the closed loop system. The aim of this paper

is to show how DC motor can be controlled by using a PID

controller in LabVIEW. DC Motor will be interfaced with

LabVIEW using an ATmega 8A Microcontroller. The speed of

the DC motor will be set by creating a Graphic User Interface

(GUI) for PID Controller in LabVIEW. LabVIEW will send

serial command to the DC motor using the PWM pins on the

Microcontroller board. DC motor will move with the speed set by

the user in LabVIEW. The speed of the dc motor will be sensed

by using the IR sensor. From the sensor, the output is sent back

to the PID Controller in LabVIEW via ATmega Microcontroller.

PID Controller compares the actual speed of the DC motor with

the set speed. If its speed is not same, PID Controller will try to

minimize the error and bring the motor to the set point value [1].

Keywords: DC Motor, LabVIEW, PID Controller, IR Sensor,

Open-Loop, Closed-Loop

I. INTRODUCTION

DC (Direct Current) Motors are two wire (power &

ground), continuous rotation motors. When the supply

power is provided, a DC motor will start spinning until that

power is removed. Most DC motors run at a high RPM

(revolutions per minute), examples being computer cooling

fans, or radio controlled car wheels.

The speed of DC motors is controlled using pulse width

modulation (PWM), a technique of rapidly pulsing the

power on and off. The percentage of time spent cycling the

on/off ratio determines the speed of the motor, e.g. if the

power is cycled at 50% (half on, half off), then the motor

will spin at half the speed of 100% (fully on). Each pulse is

so rapid that the motor appears to be continuously spinning.

A control system is an interconnection of components

forming a system configuration that will provide a desired

system response. DC Motor will be interfaced with

LabVIEW using ATmega 8A Microcontroller. The role of

Microcontroller is to pass the set speed to the DC motor

using the PWM pins and to get the data (speed) from the

motor using the IR sensor through Interrupt.

This paper is organized as follows: Section I includes the

introduction to control system, dc motor and the IR sensor.

Manuscript Received on February 2015.

Pratap S Vikhe, Associate Professor, Instrumentation &Control

Engineering Department, Pravara Rural Engineering College, Loni,

Maharashtra, India.

Neelam Punjabi, Lecturer, Biomedical Engineering Department,

Vidyalankar Institute of Technology, Wadala, Maharashtra, India.

Chandrakant B Kadu, Associate, Instrumentation Engineering

Department, Pravara Rural Engineering College, Loni, Maharashtra, India.

Section II gives the basics of proportional integral and

derivative controller. Section III gives the Hardware

Implementation Section IV Implementation of Open-Loop

and Closed Loop in Lab VIEW Section V is Conclusion

showing the results obtained.

II. PID CONTROLLER

The proportional integral derivative (PID) controller is the

most common form of feedback used in the control systems.

The popularity of PID controllers can be attributed partly to

their robust performance in a wide range of operating

conditions and partly to their functional simplicity, which

allows engineers to operate them in a simple,

straightforward manner. It can be used for various Industrial

applications. As the name suggests, PID algorithm consists

of three basic coefficients; proportional, integral and

derivative which are varied to get optimal response [3].

Unlike a simple proportional control algorithm, the PID

controller is capable of manipulating the process inputs

based on the history and rate of change of the signal. This

gives a more accurate and stable control method [5]. The

basic idea is that the controller reads the system state by a

sensor. Then it subtracts the measurement from a desired

reference to generate the error value. The error will be

managed in three ways, to:

1. Handle the present, through the proportional term,

2. Recover from the past, using the integral term,

3. Anticipate the future, through the derivative term.

In this paper we will have shown an open loop system and a

closed loop system with PID system to control the DC

motor.

1. CONTROL SYSTEM

The basic idea behind a PID controller is to read a sensor,

then compute the desired actuator output by calculating

proportional, integral, and derivative responses and

summing those three components to compute the output [2].

2. OPEN LOOP SYSTEM

An open-loop controller, also called a non-feedback

controller, is a type of controller that computes its input into

a system using only the current state and its model of the

system. A characteristic of the open-loop controller is that it

does not use feedback to determine if its output has achieved

the desired goal of the input. This means that the system

does not observe the output of the processes that it is

controlling. An open-loop controller is often used in simple

processes because of its simplicity and low cost, especially

in systems where feedback is not critical.

DC Motor Speed Control using PID Controller in Lab View

Published By:

Blue Eyes Intelligence Engineering

& Sciences Publication

Retrieval Number: C0808023315/2015©BEIESP

Figure below shows an Open-Loop System

Figure 1: Open Loop System

3. CLOSED LOOP SYSTEM

In a typical control system, the process variable is the

system parameter that needs to be controlled, such as

temperature (ºC), pressure (psi), or flow rate (liters/minute).

A sensor is used to measure the process variable and provide

feedback to the control system. The set point is the desired

or command value for the process variable. At any given

moment, the difference between the process variable and the

set point is used by the control system algorithm

(compensator), to determine the desired actuator output to

drive the system (plant).

Figure 2: Closed Loop System with PID controller

III. HARDWARE IMPLEMENTATION

This designed controller is implemented in real time for

12volt, 1500rpm, and 1.5A DC motor. The motor is

interfaced through ATmega 8A to LabVIEW and was thus

controlled. The hardware components used are as follows:

Figure 3: Hardware

ATmega 8A

The high-performance, low-power Atmel 8-bit AVR RISC-

based microcontroller combines 8KB ISP flash memory

with read-while-write capabilities, 512B EEPROM, 1KB

SRAM, 23 general purpose I/O lines, 32 general purpose

working registers, three flexible timer/counters with

compare modes, internal and external interrupts, serial

programmable USART, a byte oriented two-wire serial

interface, 6-channel 10-bit A/D converter (8-channel in

TQFP and QFN/MLF packages), programmable watchdog

timer with internal oscillator, SPI serial port, and five

software selectable power saving modes. The device

operates between 2.7-5.5 volts. By executing powerful

instructions in a single clock cycle, the device achieves

throughputs approaching 1 MIPS per MHz, balancing power

consumption and processing speed. The main aim of

ATmega microcontroller is to write the speed on the dc

motor set by the user using its PWM pins and to read the

speed sensed by the IR sensor.

Encoder

Optical encoders are devices that convert a mechanical

position into a representative electrical signal by means of

a patterned disk or scale, a light source and photosensitive

elements. With proper interface electronics, position and

speed information can be derived. Encoders can be

classified as rotary or linear for measurements of

respectively angular and linear displacements. Rotary

encoders are available as housed units with shaft and ball-

bearings or as "modular" encoders which are usually

mounted on a host shaft (e.g. at the end of a motor)[1].

Speed sensor

The sensor is always ON, meaning that the IR led is

constantly emitting light. This design of the circuit is

suitable for counting objects, or counting revolutions of a

rotating object, that may be of the order of 1500 rpm or

much more.

Driver circuit

The circuit is built around an L293D motor driver. A driver

circuit is an electrical circuit or other electronic component

used to control another circuit or other component, such as a

high-power transistor. They are usually used to regulate

current flowing through a circuit or are used to control the

other factors such as other components, some devices in the

circuit.

IV. IMPLEMENTATION OF OPEN-LOOP &

CLOSED-LOOP IN LABVIEW

A. Open-Loop System

The Block Diagram of Open-Loop is as shown below:

Figure 4: Block diagram of Open-Loop System

International Journal of Innovative Science and Modern Engineering (IJISME)

ISSN: 2319-6386, Volume-3 Issue-3, February 2015

Published By:

Blue Eyes Intelligence Engineering

& Sciences Publication

Retrieval Number: C0808023315/2015©BEIESP

The program usually begins with the while loop on the

block diagram and initializing the driver connections to

LabVIEW. VISA Write will write the command (speed) set

by the user on the ATmega microcontroller. VISA Read will

read the data (speed) sensed by the sensor. Between every

write command and read command there is a delay of

1000ms. At the end of the while loop, VISA Close

command is used which will close the session.

Front Panel of Open-Loop system is as shown below:

Figure 5: Front Panel of Open-Loop System

The front panel is the actual GUI (Graphic user Interface)

for the user to set the speed of the DC motor. For every

control on the front panel there is a respective block in

the block diagram.

B. Closed-Loop System

The Front Panel Diagram of Closed-Loop System is as

shown below:

Figure 5: Front Panel of Closed-Loop System

PID controller will compare the setpoint value with the

value received from the IR sensor. If the two values are not

same, PID controller will try to minimize this error and

bring the DC Motor to the desired speed.

The Block diagram of the Closed-Loop System is as

shown below:

Figure 7: Block diagram of Closed-Loop System

Duty cycle can be varied from 0-255 by varying the user

controlled interactive graphical dial on the front panel. The

response of the system can be changed by varying the gains

of PID controller. These VI’s will be burnt in the ATmega

microcontroller and interfaced with the dc motor. Setpoint,

set by the user will be fed into the pid controller and passed

on to the Microcontroller PWM pins. Microcontroller will

pass those PWM pulses to the motor along with supply

voltage that moves the motor. Shaft of the DC motor will

move and number of times it moves will give us the speed at

which the motor is moving. IR sensor is used for measuring

the rotation of the DC motor.

IV. CONCLUSIONS

The method adopted in this paper is low cost technique of

controlling the speed of the DC motor. DC motor is

interfaced with PID Controller in LabVIEW via ATmega

8A Microcontroller. Speed of the motor is sensed by using

the Infrared Sensor which is sent back to PID Controller as

feedback for calculating and compensating the error

produced if any. The method implemented can be used for

various industrial applications. This technique helps in

maintaining the stability of the system.

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DC Motor Speed Control using PID Controller in Lab View

Published By:

Blue Eyes Intelligence Engineering

& Sciences Publication

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