Power block:
· Power block provides the complete power supply to the whole circuitry. This block contains voltage regulator IC 7805,indiacators as LED,AC filter etc.
Track Sensor:
· This part contains 3 or 4 pair of infrared LED Tx and Rx. Which is basically placed on bottom surface of the robot. The sensor is placed about 15mm in height from the ground. and each sensors are separated by minimum 2cm from each other and 2.5 mm for tx and rx. As shown in the figure below.
· As shown in the figure 3 the sensors are connected with the LM324 which is operational amplifier with low power, Which provides appropriate power to the sensors and gives the signal to the microcontroller.
Control block:
· The 89s51 microcontroller controls all the operation of the robot movements which are based on the inputs from the sensor block.
· The led matrix provide the indication where the robot is moving its just for indication.
Output section:
· The output section contains the QUADRUPLE HALF-H DRIVER which is line driver for the dc motors.
· The motors are the 12v geared motors to move the robot.
· The output is an ASK modulated transmission signal which will transmit the signal which will give information about the robot or line follower direction.
· The transmitter module will be ST-433 which is operated on 433 megahertz. This transmitter transmits the data sent by microcontroller in which the code of the robot direction is modulated.
Receiver section:
· In this circuit, it contains complete microcontroller circuit along with the LED matrix display card which will display the position or direction of the line follower, the receiver module is STR 433.92 MHz ASK module for data receiving from the transmitter which has 100 meter range.
· This complete assembly will be placed on the user side.
Components:
IC L293D:
The L293D is a quadruple high-current half-H driver designed to provide bidirectional drive currents of up to 600-mA at voltages from 4.5 V to 36 V. It is designed to drive inductive loads such as relays, solenoids, dc and bipolar stepping motors, as well as other high-current/high-voltage loads in positive-supply applications.
Microcontroller:
We can use any of the microcontrollers like 89c51, 89s51/52, and 89c2051 in this project as per our need. It works on 5 to 12v Dc. The microcontroller is a versatile processing device which contains inbuilt memory and a CPU with on chip I/O ports.
In this circuit the controller is programmed for the sensor inputs .as the arrangement of the sensors when the sensor touches the line of the track it will give the signal to the controller and the controller will produce relevant output for individual sensor. by this means the output motor will be driven .
HT12D:
This is the decoder ic to convert the incoming signals from the receiver antenna and to send them to microcontroller this ic works on 5 to 12v DC.
The decoders receive serial addresses and data from a programmed series of encoders that
are transmitted by a carrier using an RF or an IR transmission medium. They compare the serial input data three times continuously with their local addresses. If no error or unmatched codes are found, the input data codes are decoded and then transferred to the output pins.
STT-433.92:
The STT-433 is ideal for remote control applications where low cost and longer range is required. The transmitter operates from a 1.5-12V supply, making it ideal for battery-powered applications. The transmitter employs a SAW-stabilized oscillator, ensuring accurate frequency control for best range performance. Output power and harmonic emissions are easy to control, making FCC and ETSI compliance easy. The manufacturing-friendly SIP style package and low-cost make the STT-433 suitable for high volume applications.
STR 433.92:
The STR-433 is ideal for short-range remote control applications where cost is a primary concern. The receiver module requires no external RF components except for the antenna. It generates virtually no emissions, making FCC and ETSI approvals easy. The super-regenerative design exhibits exceptional sensitivity at a very low cost. The manufacturing-friendly SIP style package and low-cost make the STR-433 suitable for high volume applications.
DRIVER CKT:
The driver circuit contains the matrix of the leds which are connected to the microcontroller and can display the sign which we want. The ULN IC is the line driver for the leds which pulls up the 5volts for the led.
Others:
As normal circuit contains resistors, capacitors, diodes, leds, crystals, etc are connected with appropriated values.
The crystal is 12 MHz quartz crystal to apply the working frequency for microcontrollers.
WORKING OF THE CIRCUIT:
· Initially the circuit of the line follower will remain linear. As the track is detected the robot will continue to run on the track. In parallel it will send the signal of the direction on which it is moving. At the receiver end the LED matrix display will display the arrows of the relative code with relative direction.
· On the track side it will be of black color type stripe on which the robot will run.
· When we enable the power the sensor assembly will detect the black line ,and gives signal to microcontroller, by user defined program microcontroller will send the signal to the motor driver circuit which is H-Bridge for motor connection that will decide the move(right or left),
· The line driver IC gives the constant power to the motor.
· On the other side as shown in figure 1, the microcontroller will also give relative signal to the IC HT 12E,this ic converts the parallel data from controller to serial data.
· The converted serial data will be transmitted by the 4 pin module which is STT 433, and this module will transmit the data to the receiver.
· On the receiver side the module STR 433 which is 14 pin module ,will detect the transmitted data and will send is to HT 12D ,which is decoder IC , it works vice versa with STT 433.
· The display module of LED matrix is droved by ULN 2803, which provides the required constant voltage for the LEDs, the anode of the matrix is connected to Port 0 and cathode is connected to Port 2 of the microcontroller as shown in the figure 2. This will display the direction of the robot in the form of arrows.
As the expansion, we can connect mobile phone to the circuit which will use the Bluetooth protocol to connect with the microcontroller. We can also connect other sensors like gas sensor, humidity sensor temperature sensor etc to the microcontroller.
INDUSTRY UTILIZATION:
- This robot is very useful in Nuclear plants at which frequent works are being done near power reactors , this robot can perform preprogrammed instructions to similar hazardous area , wecan draw a temporary or permenent path for it with very less involvements.
