MOBILE CONTROLLED AUTO PATH FINDING ROBOT

The project uses DTMF (Dual Tone Multiple Frequency) signals to control the movement of the robot. Each key on the keypad of a mobile or landline is associated to two frequencies (one for the row and one for column).First circuit is IC 8870.  IC   8870 is a DTMF to BCD decoder. So our first part of the circuit is our DTMF decoder. This part is required to interact with a mobile phone or any DTMF based phone. Whenever we press any switch from the transmitter phone then transmitter transmit some signal as per the switch press. So on every press switch there is a different signal.

Output of the DTMF decoder is BCD.The  next circuit converts BCD signal into decimal signal.In this project we use IC 74154 as a BCD to decimal decoder circuit. IC 74154 converts the BCD signal into decimal signal . Output of the 74154 is  active low.

Output of the  74154 is connected to the 89c2051 microcontroller. Ic 89c2051 microcontroller  is used to drive the motors for forward and reverse movement.

Output of the microcontroller is connected to the optocoupler circuit.Here we use IC PC 817 as a  optocoupler to interface the  microcontroller to small slow speed dc motor.

The robot can also work in the auto path finding and anti falling mode. In both the logic we use infra red sensors as a main reflective sensor. With the help of reflective sensors we can control the movement of robots as per the program.

We program the robot so that whenever there is any big obstruction near the robot then one motor stops and  robot changes its direction and moves in the other direction. For this purpose we use two sensor at the both end of the robot. With the help of these two sensor it is possible for us to check every obstruction if it is not so small.  We have also designed the robot so as to prevent falling off  from an elevated surface or in a pit.The robot senses if there is no surface to move ahead then it moves  back  for few steps and changes its direction slightly  and again goes forward .if the hole is again in front of the robot then again robot moves back and again follows the same procedure.