CELL PHONE OPERATED LAND ROVER

Abstract:-

        Conventionally, wireless controlled robots user circuits, which have a drawback of limited working range, limited frequency range and limited control. Use of mobile phones for robotic control can overcome these limitations. It provides the advantages of robust control, working range as large as the coverage area of the service provider, no interference with other controllers and up to twelve controls.Although, the apperanceand capabilities of robot vary vastly, all robots share the feature of a mechanical, movables structure under some form of control. The control of robot involves three distent phases: perception, processing, action. Generally, the preceptors are sensors mounted on the robot, processing is done by the on board microcontroller and the task is performed using motors or with some other actuators.

Introduction:- 

          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.

AIMS AND OBJECTIVES:-

          The main objective of this project is to sence the temperature variations as well to detect light. For this we have used two different kinds of sensors that are temperature sensor i.e. LM35 and LDR(Light Dependent Resistor).Here LM 35 when detects the temperature above a particular threshold it becomes active and send feedback signal which is connected to the a buzzer via microcontroller. Simultaneously the sound of this buzzer is detected by microphone and which the receiver would be able to hear that sound.

Sensors:-

The sensors are the main part of this project . the  various sensor used in this project are

1.  LM 35

The LM35 series are precision integrated-circuit temperature sensors, whose output voltage is linearly proportional to the Celsius (Centigrade) temperature. The LM35 thus has an advantage over linear temperature sensors calibrated in ° Kelvin, as the user is not required to subtract a large constant voltage from its output to obtain convenient Centigrade scaling. The LM35 does not require any external calibration or trimming to provide typical accuracies of ±¼°C at room temperature and ±¾°C over a full -55 to +150°C temperature range. Low cost is assured by trimming and calibration at the wafer level. The LM35's low output impedance, linear output, and precise inherent calibration make interfacing to readout or control circuitry especially easy. It can be used with single power supplies, or with plus and minus supplies. As it draws only 60 µA from its supply, it has very low self-heating, less than 0.1°C in still air. The LM35 is rated to operate over a -55° to +150°C temperature range, while the LM35C is rated for a -40° to +110°C range (-10° with improved accuracy). The LM35 series is available packaged in hermetic TO-46 transistor packages, while the LM35C, LM35CA, and LM35D are also available in the plastic TO-92 transistor package. The LM35D is also available in an 8-lead surface mount small outline package and a plastic TO-220 package.

Fig-LM35 Pin Description

Fig- LM35 IC Package

             

2.       LDR –

A photoresistor or light dependent resistor (LDR) is a resistor whose resistance decreases with increasing incident light intensity. It can also be referred to as a photoconductor.A photoresistor is made of a high resistance semiconductor. If light falling on the device is of high enough frequency, photons absorbed by the semiconductor give bound electrons enough energy to jump into the conduction band. The resulting free electron (and its hole partner) conduct electricity, thereby loweringresistance.

Fig- LDR Symbol

Fig- LDR

A photoelectric device can be either intrinsic or extrinsic. An intrinsic semiconductor has its own charge carriers and is not an efficient semiconductor, e.g. silicon. In intrinsic devices the only available electrons are in the valence band, and hence the photon must have enough energy to excite the electron across the entire bandgap. Extrinsic devices have impurities, also called dopants, added whose ground state energy is closer to the conduction band; since the electrons do not have as far to jump, lower energy photons (i.e., longer wavelengths and lower frequencies) are sufficient to trigger the device. If a sample of silicon has some of its atoms replaced by phosphorus atoms (impurities), there will be extra electrons available for conduction. This is an example of an extrinsic semiconductor.

TECHNOLOGY USED:-

1.   Dual-Tone Multi-Frequency (DTMF)

                 Dual-tone multi-frequency (DTMF) signaling is used for telecommunication signaling over analog telephone lines in the voice-frequency band between telephone 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 byITU-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.As a method of in-band signaling, DTMF tones were also used by cable television broadcasters to indicate the start and stop times of local commercial insertion points during station breaks for the benefit of cable companies. Until better out-of-band signaling equipment was developed in the1990s, fast, unacknowledged, and loud DTMF tone sequences could be heard during the commercial breaks of cable channels in the United States and elsewhere.

Example:

2.   Telephone Keypad

                 The contemporary keypad  is laid out  in a 3x4 grid, although the original DTMF keypad had an additional column  for four now-defunct menu  selector  keys. When used to dial a telephone number, pressing a single key will produce a pitch consisting of two simultaneous pure tone sinusoidal frequencies. The row in which the key appears determines the low frequency, and the column determines the high frequency. For           example,       pressing  the  “1” key  will  result  in  a  sound composed   of both  a  697  and  a  1209  hertz  (Hz)  tone.  The original  keypads  had  levers  inside,  so each  button activated two contacts. The multiple tones are the reason for calling the system multifrequency. These tones are then decoded by the switching center to determine which key was pressed.

Fig-DTMF keypad

 DTMF Keypad Frequencies (With Sound Clips):-

	1209 Hz	1336 Hz	1477 Hz	1633 Hz
697 Hz	1	2	3	A
770 Hz	4	5	6	B
852 Hz	7	8	9	C
941 Hz	*	0	#	D

 DTMF Event Frequencies:-

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

 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 aswell 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, relabeled, in their  now defunct  Autovon phone  system. Here they were used  before  dialing  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.

 DESCRIPTION:-

            As shown in the above block diagram, first block  is the Cell Phone.  So,it acts as a DTMF generator with  tone pending upon  key pressed. DTMF Decoder ,i.e., IC CM8870 decodes the received tone & gives binary equivalent of it to the crocontroller.The controller is programmed such that appropriate output  is given to Motor Driver IC L293D whichwill drive the two DC Motors connected to it. The concept used for driving is ‘Differential Drive’. So, ultimately the two motors rotate phone. according to the key pressed on the key pad of the cell

 Pin Diagram:-

Fig-Microcontroller(89S52)

Application:-

The applications of the Robotic Arm can broadly be classified in two categories.
• Fire Mishaps: 

In the event of a fire accident it is better to send the robot, than to send a human inside the affected area to, either search and rescue a person or for surveillance purposes. The arm can also be equipped with a fire extinguisher to put off the fire.

• Bomb Detection:

In the likely event of a bomb alert, this robotic arm can safely go, detect and diffuse the bomb instead of a human being risking his life.

• In Bio Hazardous Areas:

In areas where the probability of a chemical accident is more, like in a laboratory or in a factory, the robotic arm can be equipped with certain chemicals to stop the adverse diffusion/reaction of the chemicals. Cleaning bio hazardous debris is also one important activity in which the robotic arm can play a significant role.

• In Space Explorations as Land Rover:

Recent Chandryaan moon mission employs such robotic arms (a complete version of the robot), to survey the geographical and chemical composition of the surface of the Moon. NASA also has used such robots in its survey of Mars. The collected samples from the surface are then transported back to the space shuttle, from where other chemical tests are conducted, and results relayed back to Earth.

• In Coal Mines:

In coal mines it is quite natural that Methane gas leaks occurs. The robot can be equipped with a Methane gas sensor and warn the presence of said gas, without exposing humans to the danger.

Conclusion:-

The advantages explained earlier in this chapter justify the significance of a mobile based robotic arm. The application areas are also vast with the simplest of modifications. Since all we need is a mobile call establishment to instruct the robot due to the cell phone’s unending and cheap availability, this is highly feasible. The signals received at the robot’s mobile is decoded with DTMF decoder which is easy to use. No heavy motors are employed in the making of the robot, and thus it becomes very light weight. The level of sophistication is quite low and hence its working is user friendly.

Since this robot is highly flexible adding components to facilitate application specific working yields a robot that has high use in vast areas. This project can also be subjected to standardization and hence has a good future scope.