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ABSTRACT
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 control corresponding to
the button pressed is heard at the other end of the call. This tone is called dual tone multi
frequency tome (DTMF) 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
HT9170 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 centre. The version of DTMF used for telephone tone dialing is known as ‘Touch-
Tone.’
DTMF assigns a specific frequency (consisting of two separate tones) to each key So that it can
easily be identified by the electronic circuit. The signal generated by the DTMF encoder is a
direct algebraic summation, in real time, of the amplitudes of two sine (cosine) waves of
different frequencies.
CHAPTER 1
INTRODUCTION
Robotics is an interesting field where every engineer can showcase his creative and technical
skills. Pleasing aspect of robotics is that a robot can be made indigenously by anyone. In this
competitive world there is need for every enthusiastic, amateur to professional, to make a simple
robot having innovated applications and with robust control.
Mobile phones today became an essential entity for one and all and so, for any mobile based
application there great reception. In this scenario making a mobile phone operated land rover is a
good idea. Conventionally wireless controlled robots utilize RF circuits, which had limitations
like limited range, limited frequency ranges and controls. But a mobile phone controlled robot
can hold up these limitations. It has a robust control, unlimited range (coverage area of the
service provided), no fear of interfering with other controllers and we can have as much as
12controls.
Although the appearance and capabilities of robots vary vastly, all robots share the features of a
mechanical, moveable structure under some form of control. This control of robot involves three
distinct phases: perception, processing and action. In common preceptors are sensors mounted on
the robot, processing is done by on-board microcontroller or processor and task (action) is
performed using motors or with some other actuators.
CHAPTER 2
TECHNOLOGY USED
2.1Dual-Tone Multi-Frequency (DTMF)
Dual-tone multi-frequency (DTMF) signaling is used for telecommunication signaling over
analog telephone lines in the voice-frequency band between telephone handsets and other
communications devices and the switching center. The version of DTMF used for telephone tone
dialing is known by the trademarked term Touch-Tone, and is standardized by ITU-T. It is also
known in the UK as MF4. Other multi-frequency systems are used for signaling internal to the
telephone network.
As a method of in-band signaling, DTMF tones were also used by cable television broadcasters
to indicate the start and stop times of local commercial insertion points during station breaks for
the benefit of cable companies. Until better out-of-band signaling equipment was developed in
the 1990s, fast, unacknowledged , and loud DTMF tone sequences could be heard during the
commercial breaks of cable channels in the US and elsewhere.
2.1.1Telephone keypad
The contemporary keypad is laid out in a3x4 grid, although the original DTMF keypad had an
additional column for four now-defunct menu selector keys. When used to dial a telephone
number, pressing a single key produce a pitch consisting of two simultaneous pure tones
sinusoidal frequencies. The row in which the key appears determines the low frequency, and the
column determines the high frequency. For e.g., pressing the ‘1’ key will result in a sound
composed of both a 697 and a 1209Hz tone. The original keypads had levers inside, so each
button activated two contacts. Multiple tones are the reason for calling the system multi
frequency. These tones are then decoded by the switching center to determine which key was
pressed.
2.1.2 Tones #, *, A, B, C AND D
The Engineers had envisioned phones being used to access computers, and surveyed a number of
companies to see what they would need for this role. This led to the addition of number sign (#
sometimes called ‘octothorpe’ in this context) and asterisk or “star” (*) keys as well as a group
of keys for menu selection: A, B, C and D. In the end the lettered keys were dropped from most
phones, and it was many years before these keys became widely used for vertical service codes
such as *67 in United States and Canada for suppressing caller ID.
The U.S. military also used the letters, relabeled in their new defunct Autovon phone system.
Here they were used before dialing the phone in order to give some calls priority, cutting in over
existing calls if need be. The idea was to allow important traffic to get through every time. The
levels of priority available were Flash Override (A), Flash (B), Immediate ©, and Priority (D),
with Flash Override being the highest priority.