MOBILE PHONE OPERATED ROBOT

Radio control (often abbreviated to R/C or simply RC) is the use of radio signals to remotely control a device. The term is used frequently to refer to the control of model vehicles from a hand-held radio transmitter. Industrial, military, and scientific research organizations make [traffic] use of radio-controlled vehicles as well.

A remote control vehicle is defined as any mobile device that is controlled by a means that does not restrict its motion with an origin external to the device. This is often a radio control device, cable between control and vehicle, or an infrared controller. A remote control vehicle (Also called as RCV) differs from a robot in that the RCV is always controlled by a human and takes no positive action autonomously.

One of the key technologies which underpin this field is that of remote vehicle control. It is vital that a vehicle should be capable of proceeding accurately to a target area; maneuvering within that area to fulfill its mission and returning equally accurately and safely to base.

1.1 STATEMENT OF THE PROBLEM

The objective of our project, is to control the robot by a mobile phone (as transmitter) that makes call to the mobile phone (as receiver) attached to the robot. Now after answering the call, and 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 16F72 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 1336 Hz and 770 Hz to the other end of the mobile.

BACKGROUND OF THE PROBLEM

The First Remote Control Vehicle / Precision Guided Weapon :

This propeller-driven radio controlled boat, built by Nikola Tesla in 1898, is the original prototype of all modern-day uninhabited aerial vehicles and precision guided weapons. In fact, all remotely operated vehicles in air, land or sea. Powered by lead-acid batteries and an electric drive motor, the vessel was designed to be manoeuvred alongside a target using instructions received from a wireless remote control transmitter. Once in position, a command would be sent to detonate an explosive charge contained within the boat's forward compartment.

 The weapon's guidance system incorporated a secure communications link between the pilot's controller and the surface-running torpedo in an effort to assure that control could be maintained even in the presence of electronic countermeasures. To learn more about Tesla's system for secure wireless communications and his pioneering Implementation of the electronic logic-gate circuit read ‘Nikola Tesla — Guided Weapons & Computer Technology’, Tesla Presents Series Part 3, with commentary by Leland Anderson.

Use of Remote Controlled Vehicles During World War II :

During World War II in the European Theater the U.S. Air Force experimented with three basic forms radio control guided weapons. In each case, the weapon would be directed to its target by a crew member on a control plane. The first weapon was essentially a standard bomb fitted with steering controls. The next evolution involved the fitting of a bomb to a glider airframe, one version, the GB-4 having a TV camera to assist the controller with targeting. The third class of guided weapon was the remote controlled B-17. It's known that Germany deployed a number of more advanced guided strike weapons that saw combat before either the V-1 or V-2. They were the radio-controlled Henschel's Hs 293A and Ruhrstahl's SD1400X, known as "Fritz X," both air-launched, primarily against ships at sea.

TECHNOLOGY USED- DTMF

INTRODUCTION

DTMF (dual tone multi frequency) is the signal to the phone company that you generate when you press an ordinary telephone's touch keys. In the United States and perhaps elsewhere, it's known as "Touchtone" phone (formerly a registered trademark of AT&T). DTMF has generally replaced loop disconnect ("pulse") dialing. With DTMF, each key you press on your phone generates two tones of specific frequencies. So that a voice can't imitate the tones, one tone is generated from a high-frequency group of tones and the other from a low frequency group. Here are the signals you send when you press your Touch-tone phone keys

Digit	Low frequency	High frequency
1	697	1209 Hz
2	697	1336
3	697	1477
4	770	1209
5	770	1336
6	770	1477
7	852	1209
8	852	1336
9	852	1477
0	941	1336
*	941	1209
#	941	1477

1.3.2 KEYPAD

The DTMF keypad is laid out in a 4×4 matrix, with each row representing a low frequency, and each column representing a high frequency. Pressing a single key (such as ‘1’) will send a sinusoidal tone for each of the two frequencies (697 and 1209 hertz (Hz)). The original keypads had levers inside, so each button activated two contacts. The 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.   

.3.3 DTMF TONES

The sounds used for touch tone dialing are referred to as DTMF (Dual Tone Multiple Frequencies) tones. Each number (as well as the "#" and "*") is represented by a pair of tones. For instance, the number "1" is represented by the frequencies 1209 Hz and 697 Hz. For example, in order to generate the DTMF tone for "1", you mix a pure 697 Hz signal with a pure 1209 Hz signal.

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 the 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 the United States and Canada to suppress caller ID. The U.S. military also used the letters, relabelled, in their now defunct AutoVIN phone system. Here they were used before dialling 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 (C), and Priority (D), with Flash Override being the highest priority.

 Special tone frequencies

Event	Low Frequency	High Frequency
Busy Signal	480 Hz	620 Hz
Ringback Tone (US)	440 Hz	480 Hz
Dial Tone	350 Hz	440 Hz

National telephone systems define additional tones to indicate the status of lines, equipment, or the result of calls with special tones. Such tones are standardized in each country and may consist of single or multiple frequencies. Most European countries use a single frequency, where the United States uses a dual frequency system, presented in the following table.

were initially designed with a ratio of 21/19, which is slightly less than a whole tone. The frequencies may not vary more than ±1.8% from their nominal frequency, or the switching center will ignore the signal. The high frequencies may be the same volume or louder as the low frequencies when sent across the line. The loudness difference between the high and low frequencies can be as large as 3 decibels (dB) and is referred to as "twist." The minimum duration of the tone should be at least 70 ms, although in some countries and applications DTMF receivers must be able to reliably detect DTMF tones as short as 45ms. As with other multi-frequency receivers, DTMF was originally decoded by tuned filter banks. Late in the 20th century most were replaced with digital signal processors. DTMF can be decoded using the Goertzel algorithm

1.3.4 DTMF DECODER CONNECTED TO GSM MODULE

It is not easy to detect and recognize DTMF with satisfactory precision. Often, dedicated integrated circuits are used. It is rather complicated, so it is used only marginally. Most often, a MT8870 or compatible circuit would be used. The MT8870 is a complete DTMF receiver integrating both the band split filter and digital decoder functions. The filter section uses switched capacitor techniques for high and low group filters; the 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 on chip provision of a differential input amplifier, clock oscillator and latched three-state bus interface.

1.3.5 FEATURES OF DTMF DECODER

• Complete DTMF Receiver
• Low power consumption
• Internal gain setting amplifier
• Adjustable guard time
• Central office quality
• Power-down mode
• Inhibit mode
• Backward compatible with MT8870C and MT8870C-1

1.3.6 APPLICATIONS FOR DTMF DECODERS

• Paging systems
• Repeater systems/mobile radio
• Credit card systems
• Remote control
• Personal computers
• Telephone answering machine

2.1   DESIGN

 Several options were considered for the design of the system. The first option was to send DTMF signals through the cell phone and decode it at the receiving end and control the car. However, since the robot needed to be fully controllable and a DTMF circuit could only send 16 tones at maximum, this idea was not chosen. The other option was to use actual voice commands to control the robot.

However the team could not come up with a satisfactory decoding scheme and this idea was not implemented either. The team decided to use another option, which was to send two single-tone frequencies in a continuous manner and decode them at the receiving end. This option worked best with the requirements of the project since the two frequencies sent could be easily adjusted on the transmitter side. This would allow a larger continuous range of frequencies to be used which would allow a full analog range of control for the car. On the receiving end, it would be relatively easy to decode the signal and change it into control signals. The following block diagram summarizes the overall final design that used to solve the problem

                                                                                                                                                                                                                                                     2.2 BLOCK DIAGRAM DESCRIPTION

                

As shown in the above block diagram, Fig 1.2 the over all overview of our project is figured out and description of each component is given below :

FIRST BLOCK

It is the Cell Phone, which act as a Transmitter and it acts as a DTMF generator with tone depending upon key pressed. According to the key pressed it sends its tone to the receiver side.

SECOND BLOCK

And at the receiver side i.e. second block there is another cell phone which hear the tones pressed at transmitter side and whatever it hears it send its output to towards third block.

THIRD BLOCK

It is a DTMF Decoder, i.e., IC M8870 decodes the received tone & gives binary equivalent to the fourth block. i.e. to Microcontroller.

FOURTH BLOCK

Microcontroller processed the output according to the programming and appropriate output is given to fifth block.

FIFTH BLOCK

Motor Driver which is basically a H-Bridge made by Relay switches which will drive the four DC Motors connected to it. The concept used for driving is ‘Differential Drive’. So, ultimately the four motors rotate according to the key pressed on the keypad of the cell phone.

SIXTH AND SEVENTH BLOCK

They are DC Motors which will drive by the H-Bridge in order to move SPYROBO from one place to another.

2.3 FLOW CHART OF THE PROJECT OPERATION

The operation of our project can be described by the flow chart given below:

2.4 WHY WE ARE USING MOBILE NETWORK FOR CONTROLLING THE ROBOT?

—  Wireless-controlled robots use Radio frequency circuits, which have the drawbacks of limited working range, limited frequency range and the limited control.

—  Mobile phone for robotic control can overcome these limitations and provides the advantage of robust control, working range as large as the coverage area of the service provider, no interference with other controllers.

2.5 ADVANTAGES

This project has advantages over other remote controlled devices;

·        It has unlimited operating range because mobile network is worldwide.

·        It has little noise interference.

·        It has large bandwidth.

2.6           APPLICATIONS

·        SCIENTIFIC

  Remote control vehicles have various scientific uses including hazardous                 environments, working in the Deep Ocean, and space exploration. The majority of the probes to the other planets in our solar system have been remote control vehicles, although some of the more recent ones were partially autonomous. The sophistication of these devices has fuelled greater debate on the need for manned spaceflight and exploration. The Voyager I spacecraft is the first craft of any kind to leave the solar system. The Martian explorers Spirit and Opportunity have provided continuous data about the surface of Mars since January 3, 2004.

·        MILITARY AND LAW ENFORCEMENT

·        SEARCH AND RESCUE

·        RECREATION AND HOBBY

 DESIGN ASPECTS

For the designing of our project we require we some specific hardware and software and then interfacing the components each other to accomplish the task required by our project .

Hence our mainly consist of two parts-

1.     Hardware

2.     Software

3.1 HARDWARE REQUIREMENTS

The main components of the hardware section of our project is given as:

·        Microcontroller (PIC 16F72) 

·        Crystal Oscillator (4 MHz)

·        DTMF decoder IC(MT8870)

·        Motor driver (H-bridges using Relay switches)

·        DC Motor

·        Optocouplers

·        Voltage Regulator (IC 7805)

·        Head-phone

·        Wireless Camera

·        TV Tuner Card

·        Resistors

·        Capacitors

·        Transistors

·        LEDs

The hardware components is described in sub-section below one by one and there interfacing with each other.

3.1.1 MICRO CONTROLLER

A microcontroller is a small computer on a single integrated circuit containing a processor core, memory, and programmable input/output peripherals. We are using microcontroller of Microchip Company which is controller of PIC series called as PIC16F72. The description of this controller is given below.

3.1.1.1 PIC16F72   

High Performance RISC CPU

Only 35 single word instructions to learn

• All single cycle instructions except for program branches, which are two-cycle

• Operating speed: DC - 20 MHz clock input, DC - 200 ns instruction cycle

• 2K x 14 words of Program Memory,128 x 8 bytes of Data Memory (RAM)

• Pin out compatible to PIC16C72/72A and PIC16F872.

• Interrupt capability.

• Eight-level deep hardware stack

• Direct, Indirect and Relative Addressing modes.

Peripheral features:

High Sink/Source Current: 25 mA

• Timer0: 8-bit timer/counter with 8-bit prescaler

• Timer1: 16-bit timer/counter with prescaler, can be incremented during SLEEP via external crystal/clock

• Timer2: 8-bit timer/counter with 8-bit period register, prescaler and postscaler

• Capture, Compare, PWM (CCP) module

• 8-bit, 5-channel analog-to-digital converter

• Synchronous Serial Port (SSP) with SPI™ (Master/Slave) and I2C™ (Slave)

• Brown-out detection circuitry for Brown-out Reset (BOR)

Special Microcontroller features:

1,000 erase/write cycle FLASH program memory typical

• Power-on Reset (POR), Power-up Timer (PWRT) and Oscillator Start-up Timer (OST)

• Watchdog Timer (WDT) with its own on-chip RC oscillator for reliable operation

• Programmable code protection

• Power saving SLEEP mode

• Selectable oscillator options

• In-Circuit Serial Programming™ (ICSP™) via 2 pins

• Processor read access to program memory.

Key Reference Manual Features	PIC16F72
Operating Frequency	DC - 20 MHz
RESETS and (Delays)	POR, BOR, (PWRT, OST)
FLASH Program Memory - (14-bit words, 1000 E/W cycles)	2K
Data Memory - RAM (8-bit bytes)	128
Interrupts	8
I/O Ports	PORTA, PORTB, PORTC
Timers	Timer0, Timer1, Timer2
Capture/Compare/PWM Modules	1
Serial Communications	SSP
8-bit A/D Converter	5 channels
Instruction Set (No. of Instructions)	35