10-01-2011, 02:44 PM
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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. Recently, Sony Ericsson released a remote control car that could be controlled by any Bluetooth cell phone. Radio is the most popular because it does not require the vehicle to be limited by the length of the cable or in a direct line of sight with the controller (as with the infrared set-up). Bluetooth is still too expensive and short range to be commercially viable.
HISTORY
HISTORY OF REMOTE CONTROLLED VEHICLES:
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 precisionguided 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 maneuvered alongside a target using instructions received from a wireless remote controltransmitter. 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 page 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 moreabout 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.
TECHNOLOGY USED :
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 by ITU-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.
Telephone Keypad
The contemporary keypad is laid out in a 3×4 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. 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.
DESCRIPTION:
As shown in the above block diagram, fi is the Cell Phone. So, it acts as a DTMF generator with tone depending upon key pressed. DTMF Decoder, i.e., IC CM8870 decodes the Received tone & microcontroller. The controller
appropriate output is given to Motor Driver IC L293D which
will drive the two DC Motors connected to it. The concept
used for driving is ‘Differential Drive’. So, ultimately the two
motors rotate according to the key pressed on the keypad of the cellphone.
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 fueled 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
Military usage of remotely controlled military vehicles dates back to the first half of 20th century. Soviet Red Army used remotely controlled Teletanks during 1930s in the Winter War and early stage of World War II. There were also remotely controlled cutters and experimental remotely controlled planes in the Red Army. Remote control vehicles are used in law enforcement and military engagements for some of the same reasons. The exposure to hazards are mitigated to the person who operates the vehicle from a location of relative safety. Remote controlled vehicles are used by many police department bomb-squads to defuse or detonate explosives. See Dragon Runner, Military robot. Unmanned Aerial Vehicles (UAVs) have undergone a dramatic evolution in capability in the past decade. Early UAV's were capable of reconnaissance missions alone and then only with a limited range. Current UAV's can hover around possible targets until they are positively identified before releasing their payload of weaponry. Backpack sized UAV's will provide ground troops with over the horizon surveillance capabilities.
Search and Rescue
UAVs will likely play an increased role in search and rescue in the United States. Slowly other European countries (even some developing nations) are thinking about making use of these vehicles in case of natural calamities & emergencies. This can be a great asset to save lives of both people along with soldiers in case of terrorist attacks like the one happened in 26 Nov, 2008 in Mumbai, India. The loss of military personnel can be largely reduced by using these advanced methods. This was demonstrated by the successful use of UAVs during the 2008 hurricanes that struck Louisiana and Texas.
Recreation and Hobby
See Radio-controlled model. Small scale remote control vehicles have long been popular among hobbyists. These remote controlled vehicles span a wide range in terms of price and sophistication. There are many types of radio controlled vehicles. These include on-road cars, off-road trucks, boats, airplanes, and even helicopters. The "robots" now popular in television shows such as Robot Wars, are a recent extension of this hobby (these vehicles do not meet the classical definition of a robot; they are remotely controlled by a human). Radio-controlled submarine also exist.
