A land mine detector has given a new
direction to the field of defense. The land mine detector is a device which
locates the destination of the mine and then blows it away or is defused by
itself. The robot is controlled by a remote control and thus helps in
preventing the loss of human life. This technology indicates the person the
exact location of the mine in the surrounding area. Detection and removal of
antipersonnel landmines is at present a serious political, economic,
environmental and humanitarian problem. There exists a common interest in
solving this problem, and solutions are being sought in several engineering
fields. The best solution, albeit perhaps not the quickest, would be to apply a
fully automatic system to this important task. However, any such solution still
appears to remain a long way from succeeding. First of all, efficient sensors,
detectors and positioning systems would be needed to detect, locate and, if
possible, identify different mines. Next—and this is of paramount
importance—adequate vehicles would have to be provided to carry the sensors
over the infested fields. The case posited above would require simple sensor
arrays or terrain-scanning manipulators using just one simple sensor. During
demining operations human operators would have to stay as far away as possible
for safety. Full automation tends to produce complex systems. A reasonable
intermediate solution might be found in tele-operation and human-machine
collaboration in the control loop, a scheme that is becoming known as
collaborative control (Fong 1999, Estremera et al. 2002). The landmine detector
is a new piece of technology which is used to find mines underneath the ground.
By locating the danger it either diffuses it or blows it by its own weight.
Thus the piece of machine helps to prevent any such human disasters. Being
manually controllable the robot is much handy and much useful one in the field
of war for locating the deadly traps like mines or hand grenades.
DEFINITION OF WORK
This robot consists of a
microcontroller chip (89s52) which is programmed to follow instructions given
by the user.
It consists of a landmine detector
circuit.
On locating the bomb or threat it
gives a signal by creating a noise with the help of a buzzer on it.
A RF transmitter circuit is used to
give signals and control the robot.
The robot works on 1.3 Amp current and
12V AA size battery.
The signal given to RF receiver is
then given to the microcontroller which controls the wheels of the robot.
The robot has been provided with two
stepper motors on it having an angle of 1.8 degrees of
The signal from microcontroller is then
given to ULN 2003A IC which makes the signal of sufficient power to drive the
motors.
The mine detector circuit has a coil
of 20 turns made up of pure copper.
Due to the current flowing through it
the electromagnetic field is induced in it due to which the magnet detects the
presence of any metallic object.
On the detection of any object it
buzzes or makes noise due to a buzzer on the circuit.
P. Gonzalez de Santos et.al [1]
DYLEMA:
Using walking robots for landmine
detection and location Industrial Automation Institute-CSIC
Detection and removal of antipersonnel
landmines is an important worldwide concern. A huge number of landmines has
been deployed over the last twenty years and demining will take several more
decades, even if no more mines were deployed in future. An adequate
mine-clearance rate can only be achieved by using new technologies such as
improved sensors, efficient manipulators and mobile robots. This paper presents
some basic ideas on the configuration of a mobile system for detecting and
locating antipersonnel landmines efficiently and effectively. This paper
describes the main features of the overall system, which consists of a sensor
head that can detect certain landmine types, a manipulator to move the sensor
head over large areas, a locating system based on a global-positioning system,
a remote supervisor computer and a legged robot used as the subsystems’
carrier. The whole system has been configured to work in a semi-autonomous mode
with a view also to robot mobility and energy efficiency.
Any potential vehicle can supposedly
carry sensors over an infested field; wheeled, tracked and even legged vehicles
can accomplish demining tasks effectively. Wheeled robots are the simplest and
cheapest, and tracked robots are very good for moving over almost all kinds of
terrain, but legged robots also exhibit interesting potential advantages in
demining. For instance: robots only require a finite number of ground-contact
points, thus reducing their likelihood of stepping on an antipersonnel mine. After
detecting an antipersonnel mine, a legged robot has a higher likelihood of going
farther than do wheeled or tracked rovers. Wheels and tracks describe a continuous
path, whilst legs only need to stand on discrete points along the path. This
would enable all of a field’s potential alarms to be located before starting
the removal task, which is normally accomplished by experienced human teams or different
kinds of robots.
The inherent omni-directionality of
robots is also a great advantage for changing steering direction without
performing turning-and-backing maneuvers. Robots can negotiate irregular
terrain whilst keeping their body always leveled. This is important when
carrying onboard sensors and pieces of equipment that need to be leveled whilst
measuring. Robots can easily walk on a slope with their body leveled without jeopardizing
their stability. Mobility on stairs, over obstacles and over ditches is one of
the main advantages of robots. That means legged robots can be used to reach
dangerous areas in both structured and unstructured environments. Robots can
walk over loose and sandy terrain, and legs fitted with the proper force
sensors can identify stepped terrain to prevent slippage. A robot provides
additional motion along the x, y and z components and even body rotations
without changing its footprints. Such motion can therefore be considered
additional degrees of freedom for the robot’s sensors and onboard equipment.
Stepper motor interfacing
• The
sequence to be given to stepper motor for rotating step by step.
• Half-step-8
step sequence to drive the motor 1.8 degrees per step making 200 steps per
revolution.
• The
direction of the rotation is dictated by the stator poles. The stator poles are
determined by the current sent through the wire coils. As the direction of
current is changed, the polarity is also changed causing ht reverse motion of
the motor.
ULN 2003A
• The
89S52 lacks sufficient current to drive stepper motor windings, use driver such
as ULN 2003 to energize the stator.
• ULN
2003 is preferable over the use transistors as drivers is that it has an
internal diode to take care of back EMF.
Designing the Program
• An
algorithm is any scheme, such as a list of actions or a diagram, by which the
programmer is guided in solving the problem.
• A
common technique used to document an algorithm is diagrams called flowcharts.
• Flowcharts
visually show the program operates or flows and can be a valuable aid in
visualizing the programs.
Hardware Design
The circuit is supported by single 12V
power supply. Its functioning can be explained as follows
The Mine Detector vehicle runs with
the help of 2 stepper motors supported by microcontroller IC 89S52. The vehicle
is operated by the user with the help of remote control. The remote control
consists of RF transmitter and provides a range of up to 100 meters. The RF
receiver is mounted on PCB and is connected to the controller IC. When the user
sends a signal from the remote control, the RF receiver receives the signal.
Accordingly it sends a signal to the controller and the output of the
controller is given to the stepper motor through a current amplifier which
makes the motor run. The program for running the motor for a particular signal
from the RF transmitter is initially stored in the controller IC. The wheels of
the vehicle are attached to the motor, so as the rotor of the stepper motor
rotates, the wheels also start rotating, thus moving the vehicle in a direction
specified by the incoming signal. Now, say the vehicle is being moved in the
forward direction, and if the metal/mine detector coil comes in contact with a
nearby metal there is change in flux of the coil which sends a current through
the detector circuit. A buzzer is connected o the output of this circuit, and
an amplified voltage is applied to the metal. In this way the user is able to
detect metals or landmines (as they contain metal) with the help of landmine
detector vehicle. The main advantage of the detector vehicle is that there is
no need for the user to go near the mine to detect it underground. Thus, the
mine detector works quite in a simple way and supports the user to detect
landmines.
MICROCONTROLLER AT89S52:
• Compatible
with MCS-51 Products
• 8K
Bytes of In-System Programmable (ISP) Flash Memory Endurance: 1000 Write/Erase
Cycles
• 4.0V
to 5.5V Operating Range
• Fully
Static Operation: 0 Hz to 33 MHz
• Three-level
Program Memory Lock
• 256
x 8-bit Internal RAM
• 32
Programmable I/O Lines
• Three
16-bit Timer/Counters
• Eight
Interrupt Sources
• Full
Duplex UART Serial Channel
• Low-power
Idle and Power-down Modes
• Interrupt
Recovery from Power-down Mode
• Watchdog
Timer
• Dual
Data Pointer
• Power
off flag
ULN2003
• Seven
Darlington per package
• Output
Current 500 mA(600mA Peak)
• Output
Voltage 50 V
• Integrated
Suppressed Diodes For Inductive Loads
• TTL/CMOS
compatible inputs
78—SERIES
• Output
current in excess of 1A
• Internal
thermal overload protection
• No
external components required
• Output
transistor safe area protection
• Internal
short circuit current limit
• Available
in the aluminum TO-3 package
STEPPER MOTOR
• Current
rating: 150mA
• Voltage
rating: 12V
• Step
angle: 1.8 deg per step
RF MODULE
• Size:
42 x 29 mm.
• Frequency:
433.92 MHz.
• Sensitivity:
-108 DBm
• Modulation
Type: ASK
• Bandwidth:
±200 KHz
• Current
rating: 12 mA. (Rx), 30 mA (Tx)
• Voltage
rating: 5V.(Rx), 12V (Tx).
SENSOR COIL
• Material:
Copper.
• Length:
5m
• No
of turns: 20.
• 40
mm diameter
SELECTION CRITERIA
The Project needs following hardware
components
1. The Microcontroller AT89s52, 40
pin, 8kb flash memory.
2. ULN 2003A, 16 pin, 8bit resolution.
3. 78xx, 3 pin, internal short circuit
current limit
4. Crystal, 11.0592MHz (from
datasheet)
5. RF MODULE, Range 100 meters.
6. DARLINGTON PAIR, BC 547, 2 pairs.
7. PULLUP RESISTOR, 4k7 ohms x2.
Working
The circuit consists of one crystal
and two capacitors. The crystal is used to give the microcontroller the
required periodic pulses to make it function properly. The crystal used in the
project is of 12 MHz. The two capacitors are connected to two pins of the
crystal and are grounded at the other ends.
RESET CIRCUIT
Working
The circuit gives the required
starting pulse to the microcontroller to start the operation from the very
beginning. The 89S52 microcontroller requires the active high reset pulse. So
the capacitor is connected to positive supply and the resistor is grounded.
PULL UP RESISTORS
Working
The microcontroller pins cannot be
connected to the STEPPER MOTOR directly because the microcontroller
cannot supply all the required current. So the required remaining current is
provided through the pull-up resistors. They are designed to supply just the
enough current to the motor driver circuit.
MICROCONTROLLER:
Pin Connections of microcontroller is
as given in table below. STEPPER MOTOR is connected to Motor driver IC. Two
Motor Driver IC’s are connected to eight pins of Port 0 of Microcontroller. RF
module is connected to 4 pins of Port 1. Also we have to connect some external
devices to microcontroller such as Reset circuit, crystal circuit and pull-up
resistor along with DC power supply of 5 volts. Reset circuit consists of a 10
micro farad capacitor along with 10 K Ohm resistor, Crystal circuit consist of
a 12 MHz crystal along with two capacitors of 33 pico-farad. And pull-up
resistor consist eight inbuilt resistors.
Pin no. Description Pin no. description
P0.0 STEPPER
MOTOR 1 P2.0 Not Connected
P0.1 STEPPER
MOTOR 1 P2.1 Not Connected
P0.2 STEPPER
MOTOR 1 P2.2 Not Connected
P0.3 STEPPER
MOTOR 1 P2.3 Not Connected
P0.4 STEPPER
MOTOR 2 P2.4 Not Connected
P0.5 STEPPER
MOTOR 2 P2.5 Not Connected
P0.6 STEPPER
MOTOR 2 P2.6 Not Connected
P0.7 STEPPER
MOTOR 2 P2.7 Not connected
P1.0 Not
Connected P3.0 Not Connected
P1.1 Not
Connected P3.1 Not Connected
P1.2 Not
Connected P3.2 Not Connected
P1.3 Not
Connected P3.3 Not Connected
P1.4 RF
MODULE P3.4 Not
Connected
P1.5 RF
MODULE P3.5 Not
Connected
P1.6 RF
MODULE P3.6 Not
Connected
P1.7 RF
MODULE P3.7 Not
Connected
Supply voltage : 12 volts / 1.2 Amp
(Battery)
Microcontroller : Supply voltage 5
volts / 1 Amp
Buzzer circuit : Supply voltage 9
volts / 1 Amp
Current limiting resistor
Rlimit = 1KΩ
METAL DETECTOR
In this circuit colpitt’s oscillator
is built around first transistor. The coil L and two capacitors form a tank
circuit. 5k preset and 0.1uf capacitor sets +ve feedback to the transistor,
converting it into an oscillator. When the piece of metal (Generally Iron)
comes very close to the centre of the coil, the value L changes and the voltage
at the base of the third transistor rapidly increases and the 4th transistor
base, receives high voltage setting the transistor goes into saturation (As a
switch) and activates LED and buzzer. But when metal piece is taken away from
the coil, the base of third transistor does not get any voltage and hence
remains OFF and there by switching off the 4th transistor. The output of the
colpitt’s oscillator is a very good since wave is observed of the emitter of
the second transistor (seen on CRO). At the base of the third transistor DC
voltage is seen, because of the rectifying action of Diode and 0.1uf capacitor.
ALGORITM.
1. Start.
2. Initialize the port_1 for RF module
and port_0 for motors.
3. Define 4 direction functions for
port_0 with appropriate logic values.
4. Set pins of port_1 to logic 1.
5. Wait for signal from RF
transmitter.
6. If p_4 goes low, initialize forward
direction function.
7. If p_5 goes low, initialize reverse
direction function.
8. If p_6 goes low, initialize turn
right function.
9. If p_7 goes low, initialize turn
left function.
10. If all pins of port_1 are
logically high (1), then go back to step 5.
11. End.
PROGRAM CODE
#include<at89x52.h>
#include<math.h>
void
SF ();
void
SR();
void
SRT();
void
SLT();
void
delay(int);
int
x=200;
int
iCnt;
///port1 RF module,/port0 motor
void
main()
{
p1_4=1;p1_5=1;p1_6=1;p1_7=1;
while(1)
{
if(p1_4==0)
{
SF();
}
if(p1_5==0)
{
SR();
}
if(p1_6==0)
{
SRT();
}
if(p1_7==0)
{
SLT();
}
}
}
void
SF()
{
p0_0=0;
p0_1=0;
p0_2=0;
p0_3=1;
p0_4=1;
p0_5=0;
p0_6=0;
p0_7=0;
delay(x);
p0_0=0;
p0_1=0;
p0_2=1;
p0_3=0;
p0_4=0;
p0_5=1;
p0_6=0;
p0_7=0;
delay(x);
p0_0=0;
p0_1=1;
p0_2=0;
p0_3=0;
p0_4=0;
p0_5=0;
p0_6=1;
p0_7=0;
delay(x);
p0_0=1;
p0_1=0;
p0_2=0;
p0_3=0;
p0_4=0;
p0_5=0;
p0_6=0;
p0_7=1;
delay(x);
}
void SR()
{
p0_0=1;
p0_1=0;
p0_2=0;
p0_3=0;
p0_4=0;
p0_5=0;
p0_6=0;
p0_7=1;
delay(x);
p0_0=0;
p0_1=1;
p0_2=0;
p0_3=0;
p0_4=0;
p0_5=0;
p0_6=1;
p0_7=0;
delay(x);
p0_0=0;
p0_1=0;
p0_2=1;
p0_3=0;
p0_4=0;
p0_5=1;
p0_6=0;
p0_7=0;
delay(x);
p0_0=0;
p0_1=0;
p0_2=0;
p0_3=1;
p0_4=1;
p0_5=0;
p0_6=0;
p0_7=0;
delay(x);
}
void
SLT()
{
p0_0=0;
p0_1=0;
p0_2=0;
p0_3=1;
p0_4=0;
p0_5=0;
p0_6=0;
p0_7=1;
delay(x);
p0_0=0;
p0_1=0;
p0_2=1;
p0_3=0;
p0_4=0;
p0_5=0;
p0_6=1;
p0_7=0;
delay(x);
p0_0=0;
p0_1=1;
p0_2=0;
p0_3=0;
p0_4=0;
p0_5=1;
p0_6=0;
p0_7=0;
delay(x);
p0_0=1;
p0_1=0;
p0_2=0;
p0_3=0;
p0_4=1;
p0_5=0;
p0_6=0;
p0_7=0;
delay(x);
}
void
SRT()
{
p0_0=1;
p0_1=0;
p0_2=0;
p0_3=0;
p0_4=1;
p0_5=0;
p0_6=0;
p0_7=0;
delay(x);
p0_0=0;
p0_1=1;
p0_2=0;
p0_3=0;
p0_4=0;
p0_5=1;
p0_6=0;
p0_7=0;
delay(x);
p0_0=0;
p0_1=0;
p0_2=1;
p0_3=0;
p0_4=0;
p0_5=0;
p0_6=1;
p0_7=0;
delay(x);
p0_0=0;
p0_1=0;
p0_2=0;
p0_3=1;
p0_4=0;
p0_5=0;
p0_6=0;
p0_7=1;
delay(x);
}
void
delay(int m)
{
int j;
for(j=0;j<=m;j++)
{
}
return;
}
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