CellPhone-oPeRated land RoveR
P RaghavendRa PRaSad and . K. SuSRam Rahul
onventionally, wireless-controlled robots use RF circuits, which have the drawbacks of limited working range, limited frequency range and limited control. Use of a mobile phone 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 appearance and capabilities of robots vary vastly, all robots share the features of a mechanical, movable structure under some form of control. The control of robot involves three distinct phases: preception, processing and action. Generally, the preceptors are sensors mounted on the robot, processing is done by the on-board microcontroller or processor, and the task (action) is performed using motors or with some other actuators.
Semiconductors: IC1 - MT8870 DTMF decoder IC2 - ATmega16 AVR microcontroller IC3 - L293D motor driver IC4 - 74LS04 NOT gate D1 -1N4007rectifierdiode Resistors (all ¼-watt, ±5% carbon): R1, R2 - 100-kilo-ohm R3 - 330-kilo-ohm R4-R8 - 10-kilo-ohm Capacitors: C1 - 0.47µF ceramic disk C2, C3, C5, C6 - 22pF ceramic disk C4 - 0.1µF ceramic disk Miscellaneous: XTAL1 XTAL2 S1 M1, M2 Batt. 3.57MHz crystal 12MHz crystal Push-to-on switch 6V, 50-rpm geared DC motor - 6V, 4.5Ah battery -
In this project, the robot is controlled by a mobile phone that makes a call to the mobile phone attached to the robot. In the course of a call, if any button is pressed,
Fig. 1: Block diagram of cellphone-operated land rover
a tone corresponding to the button pressed is heard at the other end of the call. This tone is called ‘dual-tone multiple-frequency’ (DTMF) tone. The robot perceives this DTMF tone
Fig. 2: Circuit diagram of microcontroller-based cellphone-operated land rover
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with the help of the phone stacked in the robot. The received tone is processed by the ATmega16 microcontroller with the help of DTMF decoder MT8870. The decoder decodes the DTMF tone into its equivalent binary digit and this binary number is sent to the microcontroller. The microcontroller is preprogrammed to Table I take a decision for any Tones and assignments given input and outin a DTMF System puts its decision to motor Frequencies 1209 Hz 1336 Hz 1477 Hz 1633 Hz drivers in order to drive the motors for forward 697Hz 1 2 3 A or backward motion or 770Hz 4 5 6 B a turn. 852Hz 7 8 9 C T h e m o b i l e t h a t Fig. 3: Top view of the land rover 941Hz * 0 # D makes a call to the mobile phone stacked in the gebraic summation, in real time, of Table II robot acts as a remote. So the amplitudes of two sine (cosine) this simple robotic project waves of different frequencies, i.e., DTMF Data Output does not require the conpressing ‘5’ will send a tone made low High Digit Oe D3 D2 D1 D0 struction of receiver and by adding 1336 Hz and 770 Hz to the group (Hz) group (Hz) transmitter units. other end of the line. The tones and 697 1209 1 H L L L H DTMF signaling is assignments in a DTMF system are 697 1336 2 H L L H L used for telephone signshown in Table I. 697 1477 3 H L L H H aling over the line in the Circuit description 770 1209 4 H L H L L voice-frequency band to 770 1336 5 H L H L H the call switching centre. Fig. 1 shows the block diagram of the 770 1477 6 H L H H L The version of DTMF microcontroller-based mobile phone852 1209 7 H L H H H used for telephone tone operated land rover. The important dialing is known as components of this rover are a DTMF 852 1336 8 H H L L L ‘Touch-Tone.’ decoder, microcontroller and motor 852 1477 9 H H L L H DTMF assigns a spedriver. 941 1336 0 H H L H L...