DUAL TONE MULTIPLE FREQUENCY

CONTROLLED ROBOT

BY:

SHEETAL DADLANI

RONAK KHARA

SHANTANU KHARE

RINKU ROHIRA

PROJECT GUIDED BY:MRS. ARCHANA SINGHI MAM

HEAD OF DEPARTMENT:MRS. SUNITA SHARMA MAM

ABSTRACT

DTMF controlled robot is proposed that can move in any direction on a plain surface which can be controlled by using a GSM or CDMA mobile phone where the medium of communication is DTMF tones.

The robot can revolutionize the transport system of the robots and the way we operate it by a small embedded system device.

The robot is an Omni-directional robot which can be manoeuvred by a cell phone and can be used as a compact, quiet, mobile, and durable transport vehicle in cramped environments and in loading and unloading stations.

The main focus was laid on the type of movement the robot makes on the spot and its control using a cell phone.

INTRODUCTION

Conventionally, Wireless-controlled robots use RF circuits, which have the drawbacks of limited working range, limited frequency range and the limited control. Use of a mobile phone for robotic control can overcome these limitations. It provides the advantage of robust control, working range as large as the coverage area of the service provider, no interference with other controllers and up to twelve controllers.

Although the appearance and the capabilities of robots vary vastly, all robots share the feature of a mechanical, movable structure under some form of control. The Control of robot involves three distinct phases: perception, processing and action.  Generally, the preceptors are sensors mounted on the robot, processing is done by the on-board microcontroller or processor, and the task is performed using motors or with some other actuators.

BLOCK DIAGRAM

CELL PHONE

DTMF

DECODE

R

MICROCONTROLLE

R

MOTOR

DRIVER

RIGHT

MOTOR

LEFT MOTOR

WORKING OF BLOCK DIAGRAM

In this project the robot, is controlled by a mobile phone that makes call to the mobile phone attached to the robot. In the course of the call, if any button is pressed, a tone corresponding to the button pressed is heard at the other end of the call. This tone is called DTMF tone. The robot receives this DTMF tone with the help of phone stacked in the robot.

The received tone is processed by the atmega16 microcontroller with the help of DTMF decoder MT8870. The decoder decodes the DTMF tone in to its equivalent binary digit and this binary number is send to the microcontroller. The microcontroller is preprogrammed to take a decision for any give input and outputs its decision to motor drivers in order to drive the motors for forward or backward motion or a turn.

The mobile that makes a call to the mobile phone stacked in the robot acts as a remote. So this simple robotic project does not require the construction of receiver and transmitter units.

DTMF signaling is used for telephone signaling over the line in the voice frequency band to the call switching center. The version of DTMF used for telephone dialing is known as ‘Touch –Tone’.

DTMF assigns a specific frequency (consisting of two separate tones) to each key s that it can easily be identified by the electronic circuit. The signal generated by the DTMF encoder is the direct al-gebraic submission, in real time of the amplitudes of two sine (cosine) waves of different frequencies, i.e., pressing ‘5’ will send a tone made by adding 1336Hz and 770Hz to the other end of the mobile. The tones and assignments in a DTMF system shown below

DTMF BASICS

DTMF is a tone composed of two sine waves of given frequencies. Individual frequencies are chosen so that it is quite easy to design frequency filters, and so that they can easily pass through telephone lines (where the maximum guaranteed bandwith extends from about 300 Hz to 3.5 kHz). DTMF was not intended for data transfer; it is designed for control signals only.

DTMF USAGE

DTMF is the basis for voice communications control. Modern telephony uses DTMF to dial numbers, configure telephone exchanges, and so on. It is used to transfer information between radio transceivers, in voice mail applications, etc.

HOW TO TRANSMIT DTMF

Most often, dedicated telephony circuits are used to generate DTMF. On the other hand, a microprocessor can do it, too. Just connect a RC filter to two output pins, and generate correct tones via software.

FREQUENCY TABLE

HOW TO DECODE DTMF:

It is not easy to detect and recognize DTMF with satisfactory precision. Often, dedicated integrated circuits are used, although a functional solution for DTMF transmission and receiving by a microprocessor .It is rather complicated, so it is used only marginally. Most often, a MT 8870 or compatible circuit would be used.

1209 Hz

1336 Hz

1477 Hz

1633 Hz

697 Hz

1 2 3 A

770 Hz

4 5 6 B

852 Hz

7 8 9 C

941 Hz

* 0 # D

This table resembles a matrix keyboard. The X and Y coordinates of each code give the two frequencies that the code is composed of. There are 16 codes; however, common DTMF dialers use only 12 of them. The "A" through "D" are "system" codes. Most end users won't need any of those; they are used to configure phone exchanges or to perform other special functions

SERVO MOTORS

Specialized motors that can move their shaft to a specific positionDC motors can only move in one direction“Servo” • capability to self-regulate its behavior, i.e., to measure its own position and

compensate for external loads when responding to a control signalHobby radio control applications:• Radio-controlled cars: front wheel steering• RC airplanes: control the orientation of the wing flaps and rudders

Servo motors are built from DC motors by adding:• Gear reduction• Position sensor for the motor shaft• Electronics that tell the motor how much to turn and in what direction

Movement limitations• Shaft travel is restricted to 180 degrees• Sufficient for most applications

OPERATION OF SERVO MOTORS

The input to the servo motor is desired position of the output shaft.

This signal is compared with a feedback signal indicating the actual

position of the shaft (as measured by position sensor).

An “error signal” is generated that directs the motor drive circuit to power

the motor

The servo’s gear reduction drives the final output.

CONTROL OF SERVO MOTORS

Input is given as an electronic signal, as a series of pulses

• length of the pulse is interpreted to signify control value:

pulse-width modulation

Width of pulse must be accurate (s)

• Otherwise the motor could jitter or go over its

mechanical limits

The duration between pulses is not as important (ms

variations)

• When no pulse arrives the motor stops

Three sample waveforms for controlling a servo motor

DEGREES OF FREEDOM (DOF)

DOF: any direction in which motion can be made

The number of a robot’s DOFs influences its performance of a task

Most simple actuators (motors) control a single DOF

• Left-right, up-down, in-out

Wheels for example have only one degree of freedom

Robotic arms have many more DOFs

USES OF EFFECTORS

Locomotion

• Moving a robot around

Manipulation

• Moving objects around

Effectors for locomotion

• Legs: walking/crawling/climbing/jumping/hopping

• Wheels: rolling

• Arms: swinging/crawling/climbing

• Flippers: swimming

Most robots use wheels for locomotion

STABILITY

Robots need to be stable to get their job done

Stability can be

• Static: the robot can stand still without falling over

• Dynamic: the body must actively balance or move to remain stable

Static stability is achieved through the mechanical design of the robot

Dynamic stability is achieved through control

STATICALLY STABLE WALKING

If the robot can walk while staying balanced at all times it is statically

stable walking

There need to be enough legs to keep the robot stable

• Three legged robots are not statically stable

• Four legged robots can only lift one leg at a time

• Slow walking pace, energy inefficient

• Six legs are very popular (both in nature and in robotics) and allow

for very stable walking

GETTING THERE

Robot locomotion is necessary for

• Getting the robot to a particular location

• Having the robot follow a particular path

Path following is more difficult than getting to a destination

Some paths are impossible to follow

• This is due to non-holonomicity

Some paths can be followed, but only with discontinuous velocity (stop,

turn, go)

• Parallel parking

TYPES OF JOINTS

There are two main types of joints

Rotary

• Rotational movement around a fixed axis

Prismatic

• Linear movement

ANOTHER BASICS INVOLVED

DC MotorsMotor EfficiencyOperating VoltageOperating/Stall CurrentTorqueStall TorquePower of a MotorHow Fast do Motors Turn?GearingMeshing GearsGearing Effect on SpeedTorque – Speed Tradeoff

LIST OFCOMPONENTS

SR. No Description

1 Transformer 12-0-12V,750mA

2 Diode 1N4007

3 Capacitor1000uF,25V

4 Voltage regulator IC 7805

5 Capacitor 1uF

6 LED

7 Resistors

8 Disc capacitors

9 IC Base

10 PCB

11 Wires

12 Solder wire

13 Cabinet

14 Mains cord

15 Transistor BC548

FUTURE SCOPE

IR Sensors  • IR sensors can be used to automatically detect & avoid obstacles if the robot goes beyond line of sight. This avoids damage to the vehicle if we are maneuvering it from a distant place.

Password Protection  • Project can be modified in order to password protect the robot so that it can be operated only if correct password is entered. Either cell phone should be password protected or necessary modification should be made in the assembly language code. This introduces conditioned access & increases security to a great extent.

 

Alarm Phone Dialer • By replacing DTMF Decoder IC CM8870 by a 'DTMF Transceiver IC’ CM8880, DTMF tones can be generated from the robot. So, a project called 'Alarm Phone Dialer' can be built which will generate necessary alarms for something that is desired to be monitored (usually by triggering a relay). For example, a high water alarm, low temperature alarm, opening of back window, garage door, etc. • When the system is activated it will call a number of programmed numbers to let the user know the alarm has been activated. This would be great to get alerts of alarm conditions from home when user is at work.

Adding a Camera  • If the current project is interfaced with a camera (e.g. a Webcam) robot can be driven beyond line-of-sight & range becomes practically unlimited as GSM networks have a very large range.

APPLICATIONS

Scientific • Remote control vehicles have various scientific uses including hazardous environments, working in the deep ocean , and space exploration. The majority of the probes to the other planets in our solar system have been remote control vehicles, although some of the more recent ones were partially autonomous. The sophistication of these devices has fueled greater debate on the need for manned spaceflight and exploration.

Military and Law Enforcement • Military usage of remotely controlled military vehicles dates back to the first half of 20th century. Soviet Red Army used remotely controlled Teletanks during 1930s in the Winter War and early stage of World War II.

Search and Rescue  • UAVs will likely play an increased role in search and rescue in the United States. This was demonstrated by the successful use of UAVs during the 2008 hurricanes that struck Louisiana and Texas.

Recreation and Hobby  • See Radio-controlled model. Small scale remote control vehicles have long been popular among hobbyists. These remote controlled vehicles span a wide range in terms of price and sophistication. There are many types of radio controlled vehicles. These include on-road cars, off-road trucks, boats, airplanes, and even helicopters. The "robots" now popular in television shows such as Robot Wars, are a recent extension of this hobby (these vehicles do not meet the classical definition of a robot; they are remotely controlled by a human).

ADVANTAGES

DTMF’s technology is simple, low cost, as well as its already popular status in the telephone industry of today.

In the networks there are large number of nodes that are very simple and act merely as relay stations.

In healthcare (hospital and home environments), a robot that is capable of sending acoustic commands to turn on/off devices such as light switch or closing door while letting the user know that the process is taking place will be very helpful in allowing the user to feel more comfortable around robots.

CONCLUSION

This paper has described the design and implementation of experiments to test the feasibility of using the Dual Tone Multi-Frequency encoding scheme as a method for communicating simple messages.

ANY QUESTIONS??????