1 INTRODUCTION HISTORY Remotely controlled robots have been being used when a human cannot be present on site to perform a job because it is dangerous, far away, or inaccessible. Like in case of detecting land mines. Rather than following a predetermined sequence of movements, a robot is controlled from a distance by a human operator. The robot may be in another room or another country, or may be on a very different scale to the operator. In case of a DTMF controlled robot, the range is the mobile operator’s coverage area. Dual-tone multi-frequency (DTMF) signaling is used for telecommunication signaling over analog telephone lines in the voice-frequency band between mobile 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 (canceled March 13, 1984), and is standardized by ITU-T Recommendation Q.23. It is also known in the UK as MF4. Other multi-frequency systems are used for signaling internal to the telephone network. In the combat zone, the process is referred to as mine clearance. The priority is to breach the minefield quickly to create a safe path for troops or ships. Speed is vital, both for tactical reasons and because units attempting to breach the minefield may be under enemy fire. In this situation, it is accepted that mine clearance will be imperfect and there may be casualties from undiscovered mines. Correspondingly, in these mine clearance operations, the methods that are applied for detection and removal are quicker, but not exact. These methods include those that detect and remove in a single action The first step in manual demining is to scan the area with metal detectors, which are sensitive enough to pick up most mines but which also yield about one thousand false positives for every mine,and cannot detect landmines with very low metal content. (While some mines have significant metallic content and are fairly easy to detect with metal detectors, many anti-personnel mines and some anti-tank mines have a very low metal content and are much more challenging to locate). Areas where metal is detected
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Transcript
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INTRODUCTION
HISTORY
Remotely controlled robots have been being used when a human cannot be present on site
to perform a job because it is dangerous, far away, or inaccessible. Like in case of
detecting land mines. Rather than following a predetermined sequence of movements, a
robot is controlled from a distance by a human operator. The robot may be in another
room or another country, or may be on a very different scale to the operator. In case of a
DTMF controlled robot, the range is the mobile operator’s coverage area. Dual-tone
multi-frequency (DTMF) signaling is used for telecommunication signaling over analog
telephone lines in the voice-frequency band between mobile 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 (canceled March
13, 1984), and is standardized by ITU-T Recommendation Q.23. It is also known in the
UK as MF4. Other multi-frequency systems are used for signaling internal to the
telephone network.
In the combat zone, the process is referred to as mine clearance. The priority is to breach
the minefield quickly to create a safe path for troops or ships. Speed is vital, both for
tactical reasons and because units attempting to breach the minefield may be under
enemy fire. In this situation, it is accepted that mine clearance will be imperfect and there
may be casualties from undiscovered mines. Correspondingly, in these mine clearance
operations, the methods that are applied for detection and removal are quicker, but not
exact. These methods include those that detect and remove in a single action
The first step in manual demining is to scan the area with metal detectors, which are
sensitive enough to pick up most mines but which also yield about one thousand false
positives for every mine,and cannot detect landmines with very low metal content.
(While some mines have significant metallic content and are fairly easy to detect with
metal detectors, many anti-personnel mines and some anti-tank mines have a very low
metal content and are much more challenging to locate). Areas where metal is detected
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are carefully probed to determine if a mine is present, and must continue until the object
that set off the metal detector is found.
Toward the end of the 19th century, many scientists and engineers used their growing
knowledge of electrical theory in an attempt to devise a machine which would pinpoint
metal. The use of such a device to find ore-bearing rocks would give a huge advantage to
any miner who employed it. The German physicist Heinrich Wilhelm Dove invented the
induction balance system, which was incorporated into metal detectors a hundred years
later. Early machines were crude, used a lot of battery power, and worked only to a very
limited degree. Alexander Graham Bell used such a device to attempt to locate a bullet
lodged in the chest of American President James Garfield in 1881; the attempt was
unsuccessful because the metal bed Garfield was lying on confused the detector.
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GENERAL CONCEPTS
In this project the robot, is controlled by a mobile phone that makes call to theGSM modem 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 89c51 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-gebric 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
The signals generated are used by 89c51 as control inputs to the motor driver chip L293D
which controls the direction of the robot.
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A metal detector is attached at the end of the vehicle to detect the mine like objects
proactively. And give the necessary signal to the operator. For better navigation, a
wireless camera is implemented which sends the high quality pictures of the site.
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ADVANTAGES
• Simple design and construction
• Reliable control mechanism
DISADVANTAGES
• Time lag in DTMF communication
• Limitation in the range of remote surveillance owning to limited range of wireless
transmission of camera footages.
• Performance of the DC motor limit the performance of the Robot
• The metal detection cannot be performed beyond a particular distance.
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DETAILS
Dual-tone multi-frequency
Dual Tone Multi-Frequency, or DTMF, is a method for instructing a telephone switching
system of the telephone number to be dialed, or to issue commands to switching systems
or related telephony equipment.
The DTMF system uses eight different frequency signals transmitted in pairs to represent
sixteen different numbers, symbols and letters - as detailed below.
Working of IC MT8870:
The MT-8870 is a full DTMF Receiver that integrates both band split filter and decoder
functions into a single 18-pin DIP. Its filter section uses switched capacitor technology
for both the high and low group filters and for dial tone rejection. Its decoder uses digital
counting techniques to detect and decode all 16 DTMF tone pairs into a 4-bit code.
External component count is minimized by provision of an on-chip differential input
amplifier, clock generator, and latched tri-state interface bus. Minimal external
components required include a low-cost 3.579545 MHz crystal, a timing resistor, and a
timing capacitor. The MT-8870-02 can also inhibit the decoding of fourth column digits.
MT-8870 operating functions include a band split filter that separates the high and low
tones of the received pair, and a digital decoder that verifies both the frequency and
duration of the received tones before passing the resulting 4-bit code to the output bus.
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The low and high group tones are separated by applying the dual-tone signal to the inputs
of two 6th order switched capacitor band pass filters with bandwidths that correspond to
the bands enclosing the low and high group tones.
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Block diagram of IC MT8870
The filter also incorporates notches at 350 and 440 Hz, providing excellent dial tone
rejection. Each filter output is followed by a single-order switched capacitor section that
smoothes the signals prior to limiting. Signal limiting is performed by high gain
comparators provided with by stresses to prevent detection of unwanted low-level signals
and noise. The MT-8870 decoder uses a digital counting technique to determine the
frequencies of the limited tones and to verify that they correspond to standard DTMF
frequencies. When the detector recognizes the simultaneous presence of two valid tones
(known as signal condition), it raises the Early Steering flag (ESt). Any subsequent loss
of signal condition will cause ESt to fall. Before a decoded tone pair is registered, the
receiver checks for valid signal duration (referred to as character- recognition-condition).
This check is performed by an external RC time constant driven by ESt. A short delay to
allow the output latch to settle, the delayed steering output flag (StD) goes high, signaling
that a received tone pair has been registered. The contents of the output latch are made
available on the 4-bit output bus by raising the three state control input (OE) to logic
high. Inhibit mode is enabled by a logic high input to pin 5 (INH). It inhibits the detection
of 1633 Hz.
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The output code will remain the same as the previous detected code. On the M- 8870
models, this pin is tied to ground (logic low).
The input arrangement of the MT-8870 provides a differential input operational amplifier
as well as a bias source (VREF) to bias the inputs at mid-rail. Provision is made for
connection of a feedback resistor to the op-amp output (GS) for gain adjustment.
The internal clock circuit is completed with the addition of a standard 3.579545 MHz
crystal.
The input arrangement of the MT-8870 provides a differential input operational amplifier
as well as a bias source (VREF) to bias the inputs at mid-rail. Provision is made for
connection of a feedback resistor to the op-amp output (GS) for gain adjustment.
The internal clock circuit is completed with the addition of a standard 3.579545 MHz
crystal.
Single ended Input Configuration
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Tone Decoding
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89C61 8-bit Flash microcontroller
The Intel 8051 is Harvard architecture, single chip microcontroller (µC) which was
developed by Intel in for use in embedded systems. It uses CMOS technology for low
power consumption
In addition, the devices are static designs which offer a wide range of operating
frequencies down to zero. Two software selectable The Philips microcontrollers
described in this data sheet are modes of power reduction — idle mode and power-down
mode high-performance static 80C51 designs. They are manufactured in are available.
The idle mode freezes the CPU while allowing the an advanced CMOS process and
contain a non-volatile Flash RAM, timers, serial port, and interrupt system to continue
program memory that is programmable in parallel (via a parallel functioning. The power-
down mode saves the RAM contents but programmer) or In-System Programmable (ISP)
via boot loader. freezes the oscillator, causing all other chip functions to be They support
both 12-clock and 6-clock operation. inoperative. Since the design is static, the clock can
be stopped The P89C60X2 and P89C61X2 contain 512 bytes RAM and without loss of
user data. Then the execution can be resumed from 1024 bytes RAM respectively, 32 I/O
lines, three 16-bit the point the clock was stopped. counter/timers, a six-source, four-
priority level nested interrupt structure, a serial I/O port for either multi-processor
communications, I/O expansion or full duplex UART, and on-chip.
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Block Diagram
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FEATURES
• LQFP, PLCC, and DIP packages
• 80C51 Central Processing Unit
• Dual Data Pointers
– 64 kbytes Flash
• Three security bits
– 512 bytes RAM (P89C60X2)
– 1024 bytes RAM (P89C61X2)
• Four interrupt priority levels
– Boolean processor
• Six interrupt sources
– Fully static operation
• Four 8-bit I/O ports
• In-System Programmable (ISP) Flash memory
• Full-duplex enhanced UART
• 12-clock operation with selectable 6-clock operation (via software
– Framing error detection
or via parallel programmer)
– Automatic address recognition
•Memory addressing capability
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• Three 16-bit timers/counters T0, T1 (standard 80C51) and