RF CONTROLLED GPS BASED HOVERING MINE DETECTOR Mujtaba Hussain

Comsats Institute of Information Technology, Lahore Pakistan

(92) –(42)-7512080 0333 4712685

Email: coolpakistan@hotmail.com smhussain@.ciitlahore.edu.pk

Abstract: In normal practice, the traditional method used for the detection of mines is by sending a human being into the minefield that carries with him the mine detector [4]. Keeping in view the importance of human life, machines can be used to detect the mines, thus minimizing the casualty rate to zero percent. Due to the advancement in satellite receiver tracking systems, an integrated system employing latest tracking techniques using satellite receiver in the form of GPS integrated with an aerospace vehicle can be used to detect the exact location of mine in the mine field. Radio frequency transmitter controls the aerospace vehicle [2]. The idea of detecting mines by integrating the above-mentioned technologies is implemented on a hovercraft using Global Positioning System as a tracking tool. 1. Introduction: An estimated 110 million landmines are strewn across our planet in more than 70 countries. One hundred million of these landmines are small anti-personnel mines that cannot distinguish between the combat boots of a soldier and the footfall of an innocent child. Landmines kill and wound over 20,000 people each year. The most heavily mine-affected countries in the world, according to a UN study, are: Afghanistan, Angola, Bosnia-Herzegovina, Cambodia, Croatia, Eritrea, Iraq, Mozambique, Namibia, Somalia, Nicaragua and Sudan. These 12 countries together account for almost 50 percent of the landmines currently deployed in the world and also suffer the highest number of landmines casualties. Apart from aerospace vehicles like helicopters, which have an ability to hover in air, hovercrafts provide an excellent approach to solve our problem. Hovercrafts, as we know are vehicles capable of flying few inches above the ground irrespective of nature of surface on which it is hovering [1]. The surface can be land or sea or river. Placing a mine detector over it can help us to locate the mine by creating an RF link between the source and station. Integration of mine detector with GPS receiver thorough embedded system can help us to transmit the exact location of mines through this RF

link. At the same time a wireless controller controls the land marine vehicle. This minimizes the presence of humans into the minefield. The present work addresses the finding the position of mine through the integration of land marine vehicle with embedded systems, mine detector, RF link and a tracking module consisting of battery operated hand held displays along with tracking software used on Pc. The remaining organization of paper is as follows. In section 2 the block diagram and each module of the system is discussed. Module integration is also discussed in this section. Practical results of the system are presented in section 3. Problem difficulties and limitations and improvements of this prototype are outlined in section 4. Section 5 concludes the paper.

2. System Modeling

Figure 1: PAYLOAD KEPT ON LAND MARINE VEHICLE

METAL DETECTOR

RUDDER AND THRUST CONTROL

GPS RECEIVER

MICROCONTROLLER BASED CONTROL UNIT

RF TX

RF DATA RECEIVER

PC BASED SOFTWARE

MCU BASED LCD DISPLAY

MICROCONTROLLER BASED SIGNAL GENERATOR

RF CONTROL SIGNAL TRANSMITTER

Figure 2: BASE STATION SIDE

Keeping in view tracking and control features the description of this system is divided into two parts. 2.1 Control System

as shown in (Figure 5). This pulse frame generated by microcontroller is sent to the transmitter. Receiving side in (Figure 4) has pulse generator that initiates its signal ranging from 1-2ms, when it is edge triggered by the above sequence of pulses. The code written in the microcontroller generates these outputs, depending upon the signal received from parallel port.

The user has an option to control the vehicle by 2 ways Figure 3. One way is through PC based interface and other way is by joystick. A selection switch has been placed in microcontroller based pulse generator card. The user has an option to switch to either PC mode or joystick mode by this selection switch. When the user selects the PC mode, the microcontroller initiates its routines to get the signals from PC. A parallel port link has been placed between the PC and the microcontroller based frame generator. The user from PC sends signal to microcontroller and the microcontroller in turn sends the corresponding signal frame to transmitter. Our basic aim is to generate pulses

PC BASED INTERFACE

MICROCONTROLLER BASED SIGNAL GENERATOR

JOYSTICK BASED CONTROL

RF TX

b c f

a d e

PULSE FRAME a=d=Channel1 (220-1820us) b=c=f=180us e=11ms

Figure 2.1 practical system visualization

RF RX MOTOR DRIVER

MICROCONTROLLER BASED DRIVER

Figure 3: TRANSMISSION SIDE

Figure 4 : RECEIVING SIDE

The receiver used in this system is capable ofproducing pulses ranging from 1ms to 2 ms. Theoutput from receiver is integrated to H-Bridge andthrust control card. The working of the system is explained. Suppose theuser is in PC mode. On the main screen the user has topress ACTIVATE button. Unless activate button is notpressed, electronic circuit controlling the motors willnot work. This has to be done in order to preventaccidental starting of motors. When the user clicks theACTIVATE button, the corresponding signal is sent tothe microcontroller. This microcontroller in turn sendssuch a pattern of signal to transmitter which enablesthe receiver to generate 1.5ms pulse.180+1320us,where 180 is the fixed delay pulse and 1320 is channel1 and 2 pulse width). Thrust and rudder controlcircuits detect this 1.5ms pulse. Once the pulse greaterthan 1 ms or less than 2ms is detected by thrustcontrol circuit, it activates the vertical thrusters of theland marine vehicle. Now the system is in hoveringposition. The vertical thrusters will be kept activatedunless zero pulse is detected by the microcontrollercontrolling the vertical thruster driver. At the same time 1.5ms signal will bring the ruddersto zero degrees or in other words centralize therudders. Now as the transmitters is capable oftransmitting 2 channels, one channel is dedicated torudder control system while other channel is dedicatedto the H-Bridge circuit in order to have the bi-directional movement of the land marine vehicle. Nowif on channel 1, a pulse greater than 1.5ms is sent, therudders move to right direction. At the same time apulse less than 1.5ms sent on channel 1 will move therudders to the vice versa of previous configuration. Atthe same time a pulse greater than 1.5ms on channel 2will activate the forward thrusters depending upon thenature of electrical connections. However a pulse less

Figure 5: Pulses Generated

than 1.5ms will enable the vice versa of previous configuration. Same nature of working is employed in joystick control system. When the user turns ON the button, the thrusters are activated. Two joysticks on the remote control represent the two channels. By manually controlling the joysticks, land marine vehicle can be easily controlled. The description of the working of control mechanism has already been described. 2.2 Data Communication:

Figure 6: TRANSMISSION SIDE

On transmission (Figure 6) side the microcontroller receives data on its UART from the GPS receiver and after processing the data its sends the digital stream of required format to the RF data transmitter. Any input from the mine detector will change the format of data transmitted and this changed data stream will enable the receiver side to take required action.

Figure 7: RECEIVING SIDE

The RF receiver receives (Figure 7) the data stream of proper format. This stream is sent to PC as well as hand held display. The user can opt for either the options or any one of the options of using displays. The PC based software displays the incoming coordinates and keeps the log of coordinates of mines in the minefield. In the hand held display the GPS coordinates are displayed. The log of coordinates of mines in the minefield is saved in the EEPROM of the hand held display. 3.Practical Results: Initial tests procedures were conducted by using metal detector and mines with metal casing. The system was efficient enough to detect the exact location of mines. The data in the log files was confirmed by manual detection of mines. Both the results matched each other.

4. System limitations: DC Electric motors create the vertical thrust in this Land Marine vehicle. The thrust motor consumes approximately 20A (amperes) of current. Due to the limited availability of resources, instead of petrol engine, electric motor is used. Since the battery capable of producing 20A current occupies a large volume and weight, it cannot be placed on the land marine vehicle. Wires connected to thrust motor have to be stretched out of the vehicle and connected to the off board battery. This limits the long-range control of vehicle. This is one of the major limitations in this prototype system. 4.1 Suggested improvements: One of the major upgrade or improvement required by this prototype system is to change its thruster’s module, which have DC motor and its external supply. For practical and field use, the vertical thruster system should be replaced by petrol engine used in hobby aircrafts. This will make the system more practical and feasible. 5.Conlusion: Keeping in view the sophistication of technology used and the potential of system features, a brief outline of possible features is chalked out below. 5.1 Military Applications: In any theatre of war the key to success is information. The information on enemy defense lines, its capabilities to launch an attack can help the field commander to chalk out his strategy to counter the enemy’s line of defense. The prototype system developed is capable of providing information to help the commander to have an upper edge on the enemy. If the enemy’s line of defense is based upon mine field then by using the prototype system on the mine field and performing the tactical analysis of the region, coordinates of mine in terms of GPS coordinates is received. The data collected can enable the field commander to chalk out strategy to neutralize the enemy’s line of defense. Instead of sending humans in to the minefield to detect the mines, the prototype system is equally capable of doing this job without having a fear of loosing human life while in the process of searching the mines. The prototype vehicle can be used for patrolling the areas. By setting the vehicle to autopilot mode, it can be used as a surveillance vehicle. At the same time it can be used as a pilot vehicle creating a safe passage for vehicles or persons moving through the minefield.

GPS RECEIVER MICROCONTROLLER

MINE DETECTOR

PC BASED TRACKING SOFTWARE

RF DATA RECEIVER

HAND HELD DISPLAY

DATA TRANSMITTER

6.References: [1] www.hovercraft.com/ [2]inventors.about.com/library/inventors/ [3]www.ncsu.edu:8030/~cplee/Publication/ [4] www.demine.org/SCOT/Papers/Sabatier.pdf