RF Controlled Robot

In present time almost all the people are familiar with robots. Robots play a very important role in human life. Robots are a machine which reduces the human efforts in heavy works in industries, building etc. and makes life easy. In Our previous Projects we have made some robots like line follower, DTMF controlled robot, gesture controlled robot, computer controlled robot, but in this tutorial we are going to design a very interesting robot, that is RF controlled Robot. Interesting thing in this project is that it will run without using any microcontroller. Here we will run it directly by RF Decoder and Motor Driver.

RF controlled robot is controlled by using Four push button placed at transmitter side. Here we only need to push the buttons to control the robot. A transmitting device is used in your hand which also contains a RF Transmitter and a RF Encoder. This transmitter part will transmit command to robot so that it can do the required task like moving forward, reverse, turning left, turning right and stop. All these tasks will perform by using four push buttons that are placed on RF transmitter.

 

Required Components

• DC Motor - 2
• HT12D - 1
• HT12E - 1
• RF Pair - 1
• Motor Driver L293D - 1
• 9 Volt Battery - 3
• Battery Connector - 3
• Connecting wires
• Robot Chasis - 1
• 7805 - 2
• 750K resistor - 1
• 33K resistor - 1
• 1K Resistor  - 1
• PCB                                       

 

L293D Motor Driver

L293D is a motor driver IC which has two channels for driving two motors. L293D has Two inbuilt Transistor Darlington pair for current amplification and an separate power supply pin for giving external supply for motors.

 

RF Transmitter and  Receiver

This is a ASK Hybrid Transmitter and receiver module operates at 433Mhz frequency. This module has a crystal stabilized oscillator for maintain accurate frequency control for best range. There we have to need only one antenna externally for this module.

RF Transmitter Features:

• Frequency Range: 433 Mhz
• Output Power: 4-16dBm
• Input supply: 3 to 12 volt dc

 

RF Receiver Features:

• Sensitivity: -105dBm
• IF Frequency : 1MHz
• Low Power Consumption
• Current 3.5 mA
• Supply voltage: 5 volt

 

This Module is very cost efficient where long range RF communication is required. This module does not send data using UART communication of PC or microcontroller directly because there is lots of noise at this frequency and its Analog technology. We can use this module with the help of encoder and decoder ICs which extract data from the noise.

The range of transmitter is about 100 meters at maximum supply voltage and for 5 volt the range of transmitter is about 50-60 meter with using a simple wire of single code 17cm length antenna.  

 

Pin Description of RF Tx

1. GND - Ground supply
2. Data In - This pin accept serial data from encoder
3. Vcc - +5 Volt should be connect to this pin
4. Antenna - A wrapped connect to this pin for proper transmission of data

 

Pin Description of RF Rx

1. GND - Ground
2. Data In - This pin give output serial data to Decoder
3. Data In - This pin give output serial data to Decoder
4. Vcc - +5 Volt should be connect to this pin
5. Vcc - +5 Volt should be connect to this pin
6. GND - Ground
7. GND - Ground
8. Antenna - A wrapped connect to this pin for proper Reception of data

 

Circuit Diagrams and Explanation

Circuit Diagram for RF Transmitter:

 

Circuit Diagram for RF Receiver:

 

As shown in above figures, circuit diagrams for RF controlled robot are quite simple where a RF pair is used for communication. Connections for transmitter and receiver show in circuit diagrams. Two 9 volt batteries are used to power the motor driver and remaining Rx Circuit. And another 9 Volt battery is used to power the transmitter.

 

RF Controlled Robot has two main parts namely:

1. Transmitter part
2. Receiver part

[Also check: RF Transmitter and Receiver Circuit]

In transmitter part a data Encoder and a RF transmitter is used. As we have already mentioned above that we are using four push buttons to run the robot, these four buttons are connected with Encoder with respect to ground. When we will press any button encoder will get a digital LOW signal and then applied this signal serially to RF transmitter. The Encoder IC HT12E encodes data or signal or converting it into serial form and then sends this signal by using RF transmitter into the environment.

At the receiver end we have used RF receiver to receive data or signal and then applied to HT12D decoder. This decoder IC converts the received serial data to parallel and then send these decoded signal to L293D Motor driver IC. According to the received data robot runs by using two dc motor in forward, reverse, left, right and stop direction.

 

Working of RF Controlled Robot:

RF controlled robot move according to button pressed at Transmitter.

Button Pressed at Transmitter	Moving Direction of Robot
First (1)	Left
Second (2)	Right
First and Second (1 & 2)	Forward
Third and Fourth (3 & 4)	Backward
No Button Pressed	Stop

 

When we press first button (1 mention on circuit and hardware) robot start to moving left side and moving continues until the button is released.

 

When we press second button at transmitter, robot start moving in right side until button is released.

 

When we press first and second button at the same time, Robot start moving in forward direction until push buttons are released.

 

When we press third and fourth button at the same time, robot start moving in backward direction and keep going until push buttons are released.

 

And when no push Button is pressed, robot stops.