Mobile phones today become an essential entity for one and all and so, for any mobile based application there is great reception. In this scenario making a mobile phone operated robot is a good idea.
Of course we have wireless controlled robots using RF circuits, there are few drawbacks:
1. Limited range
2. Limited frequency range
3. Limited controls
4. Chances of signal interferences in that frequency range
All the above draw backs are avoided using this mobile phone controlled robot
That is: 1. robust control
2. Unlimited Range ( coverage area of the service provider )
3. No chance of interference ( sim number is unique )
4. 12 controls buttons
In this project robot is controlled by a mobile phone which makes a call to the mobile phone attached to the robot. In the course of a call if any button is pressed a tone corresponding to the button pressed is heard at the end of the call. This tone is called DTMF tone [Dual Tone Multi Frequency simply DTMF is used for telephone tone dialing. DTMF assigns a specific frequency to each key]. The robot perceives this DTMF tone with the help of a phone stacked in the robot.
Now we decode the DTMF code for each key pressed, by using DTMF decoder IC CM8870. Which coverts DTMF code to its equivalent 4bit binary digit.
Out of these 4 bit binary number , I use only 2 bits to control 2 motors of robot for direction control.
That’s it
00– stop
01 - Right turn
10 – left turn
11 - forward
This logic is given to motors using or gate ic and relay contacts circuit.
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