NEWS

WIRELESS BOMB DEFUSAL ROBOT

INTRODUCTION TO ROBOTICS

 The word robot was coined by a Czech novelist Karel Capek in a 1920 play titled Rassum’s Universal Robots (RUR). Robot in Czech is a word for worker or servant. Robots are very powerful elements of today’s industry. They are capable of performing many different tasks and operations precisely and do not require common safety and comfort elements human needs.

1.1 DEFINITION OF ROBOT

As defined by Robot Institute of America in 1979, a robot is a reprogrammable, multifunctional manipulator designed to move material, parts, tools or specialized devices through variable programmed motions for the performance of a variety of tasks.

1.2 HISTORY OF ROBOTS

In 1954, first programmable robot was designed by George Devol, who coined the term Universal Automation. He later shortened this to Unimation, which became the name of the first robot company in 1962. In 1978, The Puma (Programmable Universal Machine for Assembly) robot is developed by Unimation with a General Motors design support.

 PUMA

The robot industry entered a phase of rapid growth in 1980s. Many institutions introduced programs and courses in robotics. Robotics courses were spread across mechanical engineering, electrical engineering, and computer science departments.

 Different types of modern robots.

 In 2003, NASA’s Mars Exploration Rovers were launched toward Mars in search of answers about the history of water on Mars.

 1.3 CLASSIFICATION OF ROBOTS

 The following is the classification of robots according to Japanese Industrial Robot Association (JIRA):

  • Class 1: Manual Handling Device, A device with multiple degrees of freedom that is actuated by an operator.
  • Class2: Fixed Sequence Robot, A device that performs the successive stages of a task according to a predetermined, unchanging method and is hard to modify.
  • Class 3: Variable Sequence Robot, It is same as Class 2, but easy to modify.
  • Class 4: Playback Robot, A human operator performs a task manually by leading the robot, which records the motions for later playback. The robot repeats the same motions according to the recorded information.
  • Class 5: Numerical Control Robot, The operator supplies the robot with a movement program rather than teaching it the task manually.
  • Class 6: Intelligent Robot, A robot with the means to understand it’s environment and the ability to successfully complete a task despite changes in the surrounding conditions under which it is to be performed.

 The Robot Institute of America (RIA) only considers classes 3-6 as Robots.

 1.4 KNOWLEDGEBASE FOR ROBOTICS

 The knowledgebase of Robotics consists of various disciplines such as, mathematics, physics, biology, mechanical engineering, electrical engineering, computer engineering, and computer science. Typical knowledgebase for the design and operation of robotics systems consists:

  • Dynamic system modeling and analysis
  • Feedback control
  • Sensors and signal conditioning
  • Actuators (muscles) and power electronics
  • Hardware/computer interfacing
  • Computer programming

1.5 ROBOT COMPONENTS

A robot as a system consists of following elements, which are integrated together to form a robot.

1.5.1 Manipulator or Rover  This is the main body of the robot and consists of the links, the joints and other structural elements of the robot. Without other elements, the manipulator alone is not a robot.

1.5.2 End effector  This is the part that is connected to the last joint (hand) of a manipulator, which generally handles objects, makes connections to other machines, or performs the required tasks. A gripper, a clipper, a welding torch, a paint spray gun are few examples of End effectors.

1.5.3 Actuators or Muscles Actuators are the muscles of the manipulators. Common types of actuators are Synchronous motor, Stepper motor, AC servo motor, Brushless DC, servo motor, Brushed DC servo motor, pneumatic cylinders, hydraulic cylinders, etc.

 1.5.4 Sensors  Sensors are used to collect information about the internal state of robot or to communicate with the outside environment. Sensors integrated into the robot send information about each joint or link to the controller, which determines the configuration of robot. Robots are equipped with external sensory devices such as a vision system, touch and tactile sensors, speech synthesizers, etc. which enable the robot to communicate with the outside world.

 1.5.5 Controller  The controller is rather similar to your cerebellum, and although it does not have the power of your brain, it still controls your motions. The controller receives its data from the computer, controls the motions of the actuators, and coordinates the motions with sensory feedback information.

 1.5.6 Processor The processor is the brain of the robot. It calculates the motions of the robot’s joints, determines how much and how fast each joint must move to achieve the desired location and speeds. The processor is generally a computer which works like all other computers.

 1.5.7 Software  There are perhaps three groups of softwares that are used in a robot. One is operating system which operates the computer. The second is the robotic software which calculates the necessary motions of each joints based on the kinematic equation of the robot. The third software is group is the collection of routines and application programs that are developed in order to use the peripheral devices of the robots, such as vision routines, or to perform specific tasks.

1.6 LAWS OF ROBOTICS

 Asimov proposed three “Laws of Robotics” and later added the “zeroth law”.

  • Zeroth Law: A robot may not injure humanity or through inaction, allow humanity to come to harm.
  • First Law: A robot may not injure a human being or through inaction, allow a human being to come to harm, unless this would violate a higher order law
  • Second Law: A robot must obey orders given to it by human beings, except where such orders would conflict with a higher order law
  • Third Law: A robot must protect its own existence as long as such protection does not conflict with a higher order law.

 1.7 ROBOTS IN INDUSTRY

  • Agriculture
  • Automobile
  • Construction
  • Entertainment
  • Health care: hospitals, patient-care, surgery, research, etc.
  • Laboratories: science, engineering, etc.
  • Law enforcement: surveillance, patrol, etc.
  • Manufacturing
  • Military: demining, surveillance, attack, etc.
  • Mining, excavation, and exploration
  • Transportation: air, ground, rail, space, etc.
  • Utilities: gas, water, and electric
  • Warehouses
  1. GOALS AND OBJECTIVES

 The main goal of the project is to provide safety to the bomb disposal squad by providing an extra line of defense. The job of bomb disposal squad is a dangerous job and there is always a threat of loss of life in these jobs in worst circumstances, therefore there is a need of such a robot which can do the job of defusing the bomb so that the end user is safe from any hazard to him and if any accident occurs then there is no loss of life. Therefore our Wireless Bomb Defusing Robot (WBDR) will provide this extra line of defense to the end user. This robot can also be used for handling fire or nuclear substances and many other areas where working environment is not completely safe for humans.

 2.1 OBJECTIVES

 The main objectives of WBDR are to:

  • Provide a remote monitoring and controlling application for analysis of a suspicious packet (or bomb).
  • Allow the user to manipulate the packet using the robotic arm.
  • To provide visual feedback from the site of the packet.
  • To provide a very user-friendly control application.

 SCOPE OF PROJECT

 3.1 SYSTEM STATEMENT OF SCOPE

 The Wireless Bomb Disposal Robot uses a control application, at the user end to control the robot remotely using Wireless technology. The bomb technician controls the robot using this application. Input from the user is transmitted serially over an RF link to the Robot, where it is received, identified and relayed to the appropriate module.

 The input to the system is from the user. This input is first processed at the control application, serially transmitted over a Radio Link. This input is then received at the robot and processed again. The output of the system is the processed signal to the appropriate module. This module can be a motor of the base of the robot or the robotic arm.

 Major Inputs and Outputs of the system are Input Signals, Video Feedback, and movement of robotic arm movement of base.

 We have designed it as an assistant robot to the bomb disposal squad but there are a number of other applications of this robot such as:

  • For reconnaissance missions.
  • Fire: To provide video feedback of the site for analysis.
  • Nuclear: For handling hazardous or radioactive materials.

 3.2 THEORETICAL BACKGROUND OF PROJECT

 

The project has been designed keeping in view the current law and order situation in Indian Territory of Jammu and Kashmir and throughout the world. Everyday hundreds of trained personnel are either injured or lose their lives while defusing bombs. This can be reviewed by the countless number of news items appearing daily in newspapers around the world.

Although the idea of our project is original, a number of projects with similar functionalities can be found. For Example the British Police have a bomb disposal robot, the Israeli Army has it and it is also being used by bomb disposal squads and a number of states of USA.

The main idea of this robot is to provide the bomb disposal squad with safety and security from the risks that they face every day. Our robot provides an extra layer of protection to the bomb disposal squad by allowing them to check, analyze and even diffuse a suspicious packet before actually approaching it.

Mobile robots reduce or eliminate a bomb technician’s time-on-target. A robot takes risk out of potentially deadly scenarios and lets the bomb technician focus on what to do to an explosive device rather than on the immediate danger to life and limb. Even if a robot cannot reach an item for disruption, it can still be used to relay information to aid in tool and procedure selection to moving downrange. In addition, events recorded by a robot’s camera can provide evidence for further analysis.

 TECHNOLOGY AND TOOLS USED IN THE PROJECT

 4.1 L293D motor driver ICs

 For  the  different  motions  for  the  robot  I  have  used  6  DC  gear  motors.  Three L293Ds has been used for controlling the movement. It helps to move a motor in both clockwise and counter clock wise direction.

 4.2 434 MHz 8 Ch. Wireless Remote Control Kit

 It’s an 8 bit digital decoder wireless module. It gives 8 digital outputs which is then fed L293D for the controlling of 6 motors. This module is controlled by 8 switches to generate the outputs. It’s a long range wireless device which gives a safe distance of 213 feet.

 4.3 434 MHz transceiver module

434MHz Transceiver is an ASK Hybrid transmitter module. It uses saw resonator for frequency stability. The receiver is an ASK super heterodyne receiver with PLL synthesizer and crystal oscillator. This is ideal for short-range wireless applications.

4.4 Wireless A/V camera

Wireless A/V camera high receives sensitivity +18dB, Receive signal picture sound 0.9G/1.2G with high quality output. Maximum range is up to 200 meters.

  1. INTRODUCTION TO BASIC ELECTRONICS COMPONENTS

 

5.1 RESISTORS

Electric current is simply the motion of electrons from one place to another through a wire. The more electrons that are flowing, the higher is the current.  Resistors  have  an  apt  name:  They “resist”  the  electrical  current  going  through  them. You can think of resistors as “brakes” for electrons.  By  controlling  the  electrons  going  through  a  resistor,  you  can  make  a  circuit  do different things. Resistors may be the primary building block of circuits, so you see them quite a bit in electronics projects. Here are some of the things you can use them for:

  • Limiting current  to  another  component:  Some  parts,  such  as  light  emitting  diodes (LEDs), eat up current. Like a kid eats candy bars they try to gobble up as much as you give them. But LEDs run into a problem — they burn themselves out if they eat too much current. You can use a resistor to limit the amount of current that reaches an LED.

  • Reducing voltage to part of  the circuit:  In many circuits,  you  need  to provide different voltages  to  different  parts of  the  You can do this easily with resistors. Two resistors joined, form what’s called a voltage divider. Assuming that you have two  identical  resistors,  that  is,  they  apply  their  brakes  in  the  same  amount,  the  voltage  in between the two is exactly half that of the rest of the circuit.

  • Controlling the voltage/current going into another component: Combine a resistor and a capacitor, for example, and you create a kind of hourglass timer. Or put a resistor at the input of a transistor to control how much the transistor amplifies a signal.

  • Protecting the  inputs  of  sensitive  components:  Too  much  current  destroys  electronic components.  By  putting  a  resistor  at  the  input  of  a  sensitive  transistor  or  integrated  circuit,  you  limit  the current that reaches that transistor or circuit. Although not foolproof, this simple technique can save  you  a  lot  of  time  and money  that  you would  lose  fixing  accidental  blow-ups  of  your circuits.

5.1.1 Resistor Values 

If resistors act like brakes, then you have to have some way to change how hard you push the pedal, in order to have control over the flow of electrons. That control involves modifying the resistance of a resistor. Electronics dabblers know the amount of resistance in a resistor as the ohm, typically represented by the Greek capitalized letter omega: Ω. The higher the ohm value, the more resistance the component provides. To understand how you can adjust resistance, you should  know  that  there  are  two  basic  types  of  resistors,  fixed  and  variable. Here’s how they differ:

  • A fixed resistor supplies a pre-determined resistance to current. Color coding identifies the value of most fixed resistors. The  color  coding  starts  near  the  edge  of  the  resistor  and  is comprised of four, five, and sometimes six bands of different colors.

  • A variable  resistor,  called  a  potentiometer,  allows  for  the  continual  adjustment  from virtually no ohms to some maximum value. The potentiometer usually has the maximum value printed on it somewhere.

Fig 5.1 Colour Coding of Resistors

5.2 CAPACITORS

Capacitors store electrons by attracting them to a positive voltage. When the voltage is reduced or removed, the electrons move off. When a capacitor removes or adds electrons to the circuit in this fashion, it can work to smooth out voltage fluctuations.  In  some  cases  you  can  use capacitors  combined with  resistors  as  timers. Capacitors make possible all kinds of circuits, such as amplifiers and thousands of others. Capacitors are used for all sorts of neat applications, including,

  • Creating timers: A  kind  of  electronic  metronome,  a  timer  most  often  pairs  up  with  a

Resistor to control the speed of the tick-tick-tick.

  • Smoothing out voltage: Power supplies that convert AC current to DC often use capacitors to help smooth out the voltage so that the voltage stays at a nice, constant level.

  • Blocking DC current: When  connected  inline  (in  series) with  a  signal  source,  such  as  a microphone,  capacitors  block DC  current  but  pass AC  Most kinds of amplifiers use this function, for example. Adjusting  frequency, You  use  capacitors  to make  simple  filters  that  reject  AC  signals above or below some desired  frequency. By adjusting the value of the capacitor, it’s possible for you to change the cut-off frequencies of the filter.

Fig. 5.2 Different types of capacitors

5.2.1 Physics of the capacitor

Though  they many  sound  complicated  because  of  all  the  things  that  you  can  use  them  for, capacitors are really very simple devices. The typical capacitor has two metal plates inside it. The plates don’t touch each other.  Instead, a dielectric material separates the plates.  The charge is stored at the surface of the plates, at the boundary with the dielectric.  Because  each  plate  stores  an  equal  but  opposite  charge,  the  total  charge  in  the  capacitor is always zero.

5.3 INDUCTORS 

 

An inductor is a passive electrical device that stores energy in a magnetic field, typically  by combining the effects of many loops of electric current.

 

Fig. 5.3 Different types of Inductors

 

5.3.1 Physics of the inductor 

 

Inductance  is  a  physical  characteristic  of  any  system  of  conductors  (including  an  inductor), which  creates  a  voltage  proportional  to  the  instantaneous  rate  of  change  in  current  flowing through it. The symbol L is used for inductance in honor of the physicist Heinrich Lenz. The SI unit of inductance is the Henry (H).

5.3.2 Applications 

Inductors are closely related to electromagnets in structure, but used for a different purpose: to store energy in a magnetic field.  Inductors are used extensively in analog circuits and signal processing, including radio reception and broadcasting.  Inductors  in  conjunction  with capacitors  and  other  components  can  form  an  electronic  filter.  To filter out specific signal frequencies.  Two  (or  more)  coupled  inductors  form  a  transformer,  which  is  a  fundamental component of every national power grid. An inductor can be used as the energy storage device in a switching regulator power supply. The  inductor  is  charged  for  a  specific  fraction  of  the regulator’s  switching  frequency,  and  discharged  for  the  remainder  of  the  cycle.  This charge/discharge ratio determines the output to input voltage ratio. Inductors are also employed in electrical transmission systems, where they are used to intentionally depress system voltages or limit fault current. In this field, they are more commonly referred to as reactors.

5.4 DIODES

 

The diode is the simplest form of semiconductor. You use semiconductors in a circuit to control the flow of electrons. A diode has two terminals, each with a high resistance to current in one direction and low resistance to current in the opposite direction. Or put another way, diodes act as a one-way valve for electrons. Electrons can go through the diode in one direction but not in the other. A variety of applications use diodes and these diodes fall into numerous subtypes.

5.4.1 Commonly used diodes:

 

  • Zener: These puppies limit voltage to a pre-determined amount. You can build a voltage regulator for your circuit cheaply and easily with a zener diode.

  • Light-emitting diode (LED): All semiconductors emit infrared light when they conduct current. LEDs emit visible light. Now available in all the colors of the rainbow.

  • Silicon-controlled rectifier (SCR): The SCR is a type of switch used to control AC or DC currents. They’re common in light dimmer switches.

  • Rectifier: This basic diode transforms (referred to as “rectifying”) AC current to provide DC current only. (Remember: AC current alternates between both positive and negative values. DC current does not alternate, and is only positive or negative. See Figure 4-6 for an example.) Diodes are often referred to as rectifiers because they perform this rectifying function. form a kind of box shape; it rectifies AC to DC with maximum efficiency.

Fig. 5.4 Diode as a rectifier

 

5.4.2 Important ratings for diodes

 

  • Peak voltage and current: Except for zeners, diodes don’t have “values” like resistors and capacitors. A diode simply does its thing in controlling the flow of electrons. But that doesn’t mean all diodes are the same. Diodes are rated by two main criteria: peak inverse voltage (PIV) and current. These criteria specify the kind of diode that you should use in a given circuit. The PIV rating roughly indicates the maximum working voltage for the diode. For example, if the diode is rated at 100 volts, you shouldn’t use it in a circuit that applies more than 100 volts to the diode. The current rating is the maximum amount of current the diode can withstand. Assuming a diode is rated for 3 amps, it can’t safely conduct more than 3 amps without overheating and failing.

Diodes are identified by an industry-standard numerical system. A classic example is the 1N4001 rectifier diode, which is rated at 1.0 PIV and 50 volts. A 1N4002 is rated at 100 volts; a 1N4003 is rated at 200 volts, and so on.

5.4.3 Anode and Cathode

 

All diodes have what amounts to positive and negative terminals. The terminals go by special names: The positive terminal is called the anode, and the negative terminal is called the cathode. You can readily identify the cathode end of a diode by looking for a red or black stripe near one of the leads. Figure below shows a diode with a stripe at the cathode end. This stripe corresponds with the line in the schematic symbol for the diode. It’s important that when you follow a schematic to build a circuit you orient the diode with the line facing the specified way.

Fig 5.5 Polarity of Diode

 

5.4.4 Light-Emitting Diodes

 

If bright lights turn you on, you can appreciate the curious behavior of semiconductors: They emit light when you apply an electric current to them. This light is generally very dim and only in the infrared region of the electromagnetic spectrum. The light-emitting diode (LED), such as the light that glows yellow or green when your computer is on, is a special type of semiconductor expressly designed to emit copious amounts of light. Most LEDs are engineered to produce red, yellow, or green visible light, but some special-purpose types emit infrared, blue, and even white light. LEDs carry the same specifications as any other diode, but they usually have a pretty low current rating. An LED has a PIV rating of about 100 to 150 volts, with a maximum current rating of under 50 milliamps. If more current passes through an LED than its maximum rating allows, the LED burns up.

  1. WIRELESS A/V CAMERA TRANSCIEVER

 

 

6.1 PACKAGE INCLUDES:

  1. Wireless Outdoor Cam
  2. Receiver with Antenna
  3. A/V Cable
  4. Dip Switch Tool
  5. Power Adapters
  6. Security Stickers
  7. Mounting Hardware

 

  1. b.                   c.

  1. e.                                             g.

 

Fig. 6.1 Camera package components

 

 

 

 

6.2 Directions for TV connection

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

6.3 Directions for VCR/DVD Recorder Connection

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

6.3 Viewing the Wireless Outdoor Cam connected directly to a TV

 

  • Connect the Camera and Receiver as described in Connection Guide Direct to TV.
  • Plug in the Receiver and Cameras.
  • Turn on your TV.
  • Press the INPUT button on your TV’s Remote Control until your camera / receiver appears on screen. The majority of TVs will label this button as INPUT, A/V, SOURCE, AUX, TV/AV, and Channel 0. If you are unable to change the input on your TV, consult the TV’s instruction manual or contact your TV’s manufacturer.

6.4 Viewing and Recording the Wireless Outdoor Cam on a VCR or DVD Recorder

 

  • Connect the camera and receiver as described in the VCR/DVD Recorder Connection Guide.
  • Plug in the Receiver and Cameras.
  • Turn on your TV and VCR.
  • Play a tape to confirm your TV is on the correct channel, then press stop.
  • Press the INPUT button on your VCR’s Remote Control until your camera / receiver appears on screen. The majority of TVs will label this button as INPUT, A/V, SOURCE, AUX, TV/AV, and Channel 0.

The INPUT button is sometimes labeled Input, Source, Line In, L1, L2, AUX, A/V, channel 0 etc. Consult the TV or VCR instruction manual for details about changing input channels on your device.

6.5 CAMERA PLACEMENT AND INTERFERENCE

 

The Wireless Outdoor Cam operates on 2.4GHz frequency. Some devices such as wireless routers, microwaves, cordless phones can cause interference and affect picture quality as they use the same frequency. If you are experiencing interference or poor image quality try the following steps:

  • Move or orient the camera in a different location adjust or aim the receiver antenna.
  • Limit the number of walls, floors between the camera and receiver as this can dramatically alter picture quality.
  • Dense materials such as concrete or metal will impede the wireless signal; move The camera and/or receiver away from dense materials.
  • If possible keep the camera and receiver away from or move conflicting devices such as wireless routers, microwaves, cordless phones.
  • Make sure all cameras are set to different camera channels disconnect all other wireless devices to find out which is causing the problem and adjust your setup accordingly.
  • Analog wireless cameras are not recommended for use with DVR systems.

Setting

  • TECHNICAL SPECIFICATIONS

 

6.6.1 Video

  • Image Sensor———– 1/3” CMOS
  • Video Quality ———–380 TV Lines
  • Number of Effective Pixels NTSC: ———–510 x 492 / PAL: 628 x 582
  • Electronic Shutter ———–1/60 – 1/15,000 NTSC / 1/50 – 1/15,000 PAL
  • Signal / Noise Ratio ———– > 48Db
  • White Balance ———–Automatic
  • Gain Control ———–Automatic
  • Backlight Compensation ———–Yes
  • Day/Night Mode Color during the day / Switches to B&W at night
  • Minimum Illumination ———–0 Lux (IR On)
  • Lens ———–6mm
  • Viewing Angle ———–53 degrees

 

6.6.2 Night Vision

  • Night Vision Distance ———–Up to 26ft / 8m
  • Number of infrared LEDs ———–11

6.6.3 Wireless

  • Digital or Analog ———–Analog
  • Max Transmission Range ———–165ft / 50m
  • Typical Range ———–65ft / 20m
  • Frequency ———–2.4GHz
  • Transmission Channels ———–4

6.6.4 General

  • Indoor/Outdoor ———Indoor or Outdoor
  • Operating Power ———–DC 12V
  • Operating Temperature ———– (-10°C ~ 50°C / -14°F ~ 122°F)
  • Body Construction ———–Aluminum
  • Dimensions Camera & Stand ———– 5.1” x 2.0” x 2.0” / 130mm x 50mm x 50mm
  • Weight – ———–Camera & Stand 8.6oz / 245g
  • Dimensions Receiver ———–1.0” x 3.1” x 4.3” / 25mm x 80mm x 110mm
  • Weight – ———– Receiver 6.5oz / 185g

  1. INTRODUCTION TO MOTOR DRIVER L293D

Whenever a  robotics hobbyist  talk about making a  robot,  the  first  thing comes  to his mind  is making  the  robot  move  on  the  ground and there are  always  two  options  in  front  of  the designer whether to use a DC Motor or a stepper motor. When it comes to speed, weight, size, cost… DC motors are always preferred over stepper motors. There are many things which you can  do  with  your  DC  motor  when  interfaced  with  a microcontroller.  For example you can control the speed of motor, you can control the direction of rotation, and you can also do encoding of the rotation made by DC motor i.e.  Keeping track of how many turns are made by your motors etc.  So  you  can  see  DC  motors  are  no  less  than  a  stepper  motor. In this part of tutorial we will learn to interface a DC motor with a microcontroller. Usually H- bridge is preferred way of interfacing a DC motor. These days many IC manufacturers have H-bridge motor drivers available in the market like L293D is most used H-Bridge driver IC. H-bridge can also be made with the help of transistors and MOSFETs etc. rather of being cheap, they  only  increase  the  size of  the  design  board, which  is  sometimes  not  required  so  using  a small 16 pin IC is preferred for this purpose.

 

7.1 H-Bridge

 

Fig. 7.1 H- Bridge

 

7.2 L293D Dual H-Bridge Motor Driver 

 

L293 series of chips are power H-bridge motor drivers. The L293B and D have been used  for several  years  in  many MIT  robot  controller  boards,  such  as  the  6.270  Rev  2.1  board  and inboard. Unfortunately,  they  are  often  hard  to  find  and  usually  can’t  be  bought  in  single quantity.  The L293B and D chips are both in 16-pins dip packages, and both have two h-bridge drivers. An H bridge is typically capable of running one DC motor bidirectional (forward, backwards, off), or two separate motors unidirectional (forward, off). Thus a L293 chip can run two motors bidirectional, or 4 unidirectional.  L293 chips take logic-level inputs to direct the H-bridges, and have a separate pin for the motor supply (which is often higher than the standard 5V logic supply).  The L293B and D chips have identical pinouts, but have two differences. The first is that the L293D can run motors up to 600 ma, while the L293B can only run all the way up to 1 amp per H-bridge. The other, and perhaps more  important difference,  is that  the L293D has protection diodes which shunt  the current spikes produced by  inductive  loads (such as DC motors) when they  are  turned  on  or  off  (such  as  during  the  armature  contact  switching  or  pulse-width modulation).  The  L293B  has  no  such  diodes,  so  the  user  must  usually  add  his  own.  A Proprietary of Robosapiens India approach used on the MIT 6.270 board is to piggyback the two types of chips:  the two give about 1.6A, and the D chip has the protection diodes.

Fig. 7.2 PIN Diagram of L293D

7.3 Interfacing

 

Fig. 7.4 Diagram of Interfacing

  1. WIRELESS CONTROL SYSTEM

Wireless control system usually consists of an encoder that automatically generates serial data that contains both address bits and data bits and an RF transmitter module that sends the serial data. The receiver portion consists of an RF receiver module and a decoder that desterilizes the received data, checks to see if the received address bits match its own bit settings and sends valid data bits to output terminals or drivers. Address bits are used to give an identity to transmitters and receivers so that only those with identical address settings can process data.

Fig. 8.1 WIRELESS RF TRANSMITTER & RECEIVER

 

Fig. 8.2 TRANSMITTER MODULE CONNECTION Circuit Diagram

Fig. 8.3 RECIEVER MODULE CONNECTION Circuit Diagram

8.1 Transmitter-434

 

  • The transmitter output is up to 8mW at 433.92MHz with a range of approximately 400 foot (open area) outdoors.
  • Indoors, the range is approximately 200 foot, and will go through most walls
  • The TWS-434 transmitter accepts both linear and digital inputs, can operate from 1.5 to 12 Volts-DC, and makes building a miniature hand-held RF transmitter very easy.

 

               

      Fig. 8.4 Transmitter                                                         Fig. 8.5 Receiver

8.2 Receiver-434

 

  • The receiver also operates at 433.92MHz, and has a sensitivity of 3uV. The RWS-434 receiver operates from 4.5 to 5.5 volts-DC, and has both linear and digital outputs.
  • The receiver section using the HT-12D decoder IC for a 4-bit RF remote control system.

 

 

 

8.3 ENCODER IC HT640 IC

It is one of its kinds of IC which is used to decode the incoming parallel signal & give an output serially.

 

 

 

 

 

 

 

 

Fig. 8.6 Encoder IC HT640 PIN Diagram

 

 

8.3.1 Features

  • Operating voltage: 2.4V~12V.
  • Low power and high noise immunity CMOS technology.
  • Low standby current.
  • Three words transmission.
  • Built-in oscillator needs only 5% resistor.
  • Easy interface with an RF or infrared transmission media.
  • Minimal external components.

 

8.4 DECODER IC HT648 IC

 

  • Operating voltage: 2.4V-12V.
  • Low power and high noise immunity CMOS technology.
  • Low standby current.
  • Capable of decoding 18 bits of information.
  • Pairs with HOLTEK’s 318 series of encoders.
  • 8-18 address pins.
  • 0-8 data pins.
  • Two times of receiving check.
  • Built-in oscillator needs only a 5% resistor.
  • Valid transmission indictor.
  • Easily interface with an RF or an infrared transmission medium.

 

Fig. 8.7 DECODER IC HT648 IC PIN Diagram

 

 

 

  1. SIMPLE MAGNETIC GRIPPER SMG

 

The gripper module was designed for gripping and temporary secure holding of work pieces or other objects. The product is intended for installation / mounting in machines and equipment. The requirements of the applicable directives must be observed and complied with. The product may be used only within the range of its technical data.

Fig. 9.1 SMG

9.1 Environmental and operating conditions

 

  • Use the unit only within the application parameters defined in the Technical Catalog. The most recent version applies.
  • Clean ambient conditions at room temperature are required. If these conditions are not ensured, the maintenance interval will be shorter, depending on the actual utilization.
  • The environment must be free of splashing water and vapors, and also of abrasive dust and process dust. This does not apply to units designed especially for unclean environments.

 

 

 

9.2 Assembly and dimensions

 

The gripper is fixed by the base. It is centered using the fit bolts at the base and/or using an alignment pin at the base.

Fig. 9.2 Dimensions and assembly of SMG

  1. STRUCTURAL VIEW OF THE WBDR

Fig. 10.1 Structural view of WBDR

L293D

L293D

Fig. 10.2 SUBSYSTEM DESCRIPTION

Fig. 10.3 SUBSYSTEM FLOW DIAGRAM

10.4 System Resources

10.4.1 People

  • End User: An end user, who is trained to use the application, provides the actual controls for the robot to do its operations. The end user is not such a technical job so for this purpose any ordinary person with a small background of computers can be trained to do the desired operations. In the case of a bomb disposal squad, usually the end user is the one who knows all about the bomb diffusion mechanism and has a good knowledge of the type of bombs and how to counter those bombs.

  • Hardware Designers: The hardware designers in this project have designed the whole of the hardware including the Robotic base and different mechanical works in this project.

10.4.2 Hardware

The recommended minimum hardware required for the best performance of the robot’s application is as follows:

  • TV Card for Video Input
  • Wireless Data Transceivers

Robot comprises of the following hardware:

  • Wireless Camera mounted on the robotic arm
  • Serial Data Transceivers
  • Max-232 level converter IC
  • L293D IC for motor driving

10.5 Test Plan

This project contains two components the software component and the hardware component. The software component consists of the control application. The hardware component comprises of the robot. Both these two components have further internal components. All these components had to be tested individually and after being integrated as well.

10.5.1 System Test and Procedure

The wireless bomb disposal robot consists of a number of modular components. These modules have been tested, verified individually and then integrated with other modules.

10.5.2 Testing strategy

A modular approach has been used in designing the robot and the same approach has been taken in its testing. The following are the modules that have been tested:

  • The Software Application
  • The Robotic Base
  • The DC Motor Circuit

10.5.3 The DC Motor Circuit

The DC motor has an H-Bridge circuit, which has been constructed using three L293D. Each L293D acts as a switch, which can turn on or off the DC Gear Motors using control signals from the microcontroller. The circuit has been tested on a breadboard by applying voltage and the control signal.

10.5.4 Integration Testing

After the individual testing, the robot underwent integration testing. All circuits were mounted on the robot, connected to the microcontroller circuit and tested. Control signals from the serial port of the PC were generated using the control application and tested by turning on or off the appropriate motor.

  1. FUTURE ENHANCEMENTS

The system that we have built is a working prototype of a robot, which should be compact, fast and accurate. This prototype may not have the features and reliability of the original design. It is only being developed to ensure that the design is feasible, not impractical and can be implemented on a much larger scale in a more efficient way. It can be used to design such a robot, which can be small in size, fast and accurate in its movements. The gripper as compared to the ones, made by professional companies is not very efficient. But it can still perform some level of object manipulation. Hence the future enhancements may include a much smaller, faster, more reliable machine. It may have the ability to handle a much wider range of objects and the ability to maneuver them to much safer places. Some of these enhancements are described below.

  • Compact Design

A compact design results in a much faster motion and thus increases the accuracy and efficiency. Therefore the robot can be enhanced to be of much smaller size for the purpose of a faster and accurate operation. Compact design is also required where the situation demands the robot to reach for small places. For example, in the aftermath of an earth quake, the robot has to search for people trapped under the rubble. It has to enter holes where humans cannot enter. Hence a compact robot will easily do the job.

  • Quick Movement

Being a bomb disposal robot, it requires very fast movement. This is required as the bomb disposal squad have very little time in checking out the bomb and then defusing it. Therefore a fast robot is necessary to be successfully used as a Bomb Disposal Robot.

  • Improved Reliability

At the moment the turning mechanism of the robot is based on the DC motor, which is not that accurate. Also the shoulder of the robotic arm or the base of the robotic arm also depends on the motion of a DC motor, which is not very feasible for the accurate motion of the robotic arm, which is necessary. The robot can be improved to be more reliable and accurate by installing stepper motors instead of the DC motors, which are more accurate and also have the feature of the holding torque, which enables the movement of heavy object with ease.

  • Removable Gripper/Multi-Gripper Robotic Arm

The gripper attached to the robotic arm is fixed at the moment that is, it will only work with the specific shaped of objects. Placing a gripper that can be removed and replaced by another gripper can solve this problem or a multi gripper robotic arm can be developed with more than 2 types of grippers for different type of materials and for different shaped of the objects. This will enable the robotic arm to grip and move objects, which are complex and cannot be easily moved with a single or a basic gripper.

  • Night Vision Camera

The robot equipped with a wireless camera, which is not very useful in situations where the visibility or light level is very low. For night mode it will be almost impossible for identifying objects because the lights, which are provided on the robot, are fixed therefore it may not be possible to view those objects which are in the dark. For night mode or places where light is low a night vision camera can be mounted on the robot instead of a standard camera, which will increase the visibility in case of no light at all.

  1. CONCLUSION

The Wireless Bomb Defusing Robot has been designed in such a way that it can cater to the needs of the bomb disposal squad, the military, the police and also for the personnel who handle radioactive materials. It has countless applications and can be used in different environments and scenarios. For instance, at one place it can be used by the bomb disposal squad, while at another instance it can be send for handling mines. Another application can be to provide up to date information in a hostage situation. The major advantages of this robot are:

  • It can be altered to suit the needs of the user
  • It is fast and robust.
  • It can handle different loads.
  • It can be controlled remotely.
  • It has video feedback.
  • It has its own power supply.
  • It has a 3-degree of freedom robotic arm.
Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s