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Either own chassis can be designed or available chassis can be used.
Provisions are made to fix sensors, SPDuino Board, small castor wheel etc.,
clamp is fixed to attach motors.
MOTOR
RPM: 150 RPM at 12 v
This is plastic geared motor and has D type shaft.
This is used in autonomous robots and line follower robots etc.,
WHEEL
Diameter: 7 cm
Width: 8 mm
These wheels are used for BO/ Plastic geared, D type shaft motors.
This wheels are preferred for obstacle avoider kind of robots.
CASTOR WHEEL
Base plate diameter - 27.5 mm
Caster wheel diameter - 13.5 mm
Wheel height - 18 mm
The small castor wheel is an omni-directional wheel.
This wheel is used as free support front wheel for robots.
SPDUINO BOARD AND SHIELD
Specifications of the SPDuino Board and Auton shield.
SPDUINO BOARD
Microcontroller: ATmega328
Operating Voltage: 5V
Input Voltage (recommended): 7-12V
Input Voltage (limits): 6-20V
Digital I/O Pins: 14 (of which 6 provide PWM output)
Analog Input Pins: 6
DC Current per I/O Pin: 40 mA
DC Current for 3.3V Pin: 50 mA
Flash Memory: 32 KB (ATmega328) of which 2 KB used by bootloader
SRAM: 2 KB (ATmega328)
EEPROM: 1 KB (ATmega328)
Clock Speed: 16 MHz
AUTON SHIELD
Input voltage: 7-14V
Provided with stackable headers
Reverse polarity protection
On board 5V, 1.5Amps regulator
Equipped with L293D dual motor driver
Interfaces
2 DC Motors
13 standard sensor ports (of which 6 ports can be used for analog sensors)
Line array sensor port
Pins compatible with Hobby servos
SENSOR
Voltage: 5V
Output type: Digital / Analog (soldered as per requirement)
Size: 40 x 22.8 mm
Generally IR sensors are used for obstacle detection but for more precision and accuracy Ultrasonic sensor can also be used.
The interfacing pins of the sensor can be directly connected to the port in the shields.
3
Robot Assembling
FIXING CLAMP AND CASTOR WHEEL
Clamp is fixed in the given provision with screws.
Small castor Wheel is fitted in front side of the chassis with screws.
FIXING THE MOTOR
The clamp has many holes to connect the motor in any desired position.
Both the motors are fixed in the appropriate holes in the clamp.
The shaft of the motor should face the other end so as to fix the wheel.
FIXING THE WHEELS TO CHASSIS
The wheels are fitted to the shaft of both the motors.
They are screwed in the axle of the wheel.
FIXING SPDUINO BOARD AND SHIELD
To fit the board in chassis the long screw is inserted the board and required spacers are added to it.
The space between the board and chassis is separated by the spacers.
Now the board is fixed in the chassis with screws already connected to it.
Above the board the Auton shield is connected using the stackable headers.
Now the sensors are fixed in front side of the robot, covering left, right and center coverage area.
4
Obstacle Avoider wiring
CONNECTING SENSORS AND MOTOR
All the three sensors are connected in the A0,A1,A2 ports in the auton shield or others ports but the same port should be declared in the program
Both the motors are connected in the motor terminals M1,M2 respectively.
Now the Obstacle Avoider robot is ready to program.
5
Obstacle Avoider Logic
The program should be framed in such a way that all the conditions faced by the robot is included in the program.
SENSOR OUTPUT
When an IR sensor senses an obstacle the output is HIGH (5V)
When it does not sense an obstacle the output is LOW (0V)
This is programmed for left side whenever it detects a junction (left priority)
The motor is directed according to the sensor signals.
LS CS RS
0 0 0 ( no obstacle detected - robot moves forward)
0 0 1 ( right sensor senses obstacle - robot should turn left)
0 1 0 ( center sensor senses obstacle - robot takes left as per priority)
1 0 0 ( left sensor senses obstacle - robot should turn right)
0 1 1 ( center & right senses obstacle - robot should turn left)
1 1 0 ( center & left senses obstacle - robot should turn right)
1 0 1 ( right & left senses obstacle - robot should turn left as per priority)
1 1 1 ( all three sensors senses obstacle - robot turns left as per priority)
6
Obstacle Avoider - Direction Control
The robot basically does 4 movements:
Forward
Backward
Right
Left
Four pins 3,5,6,11 in the Auton shield are programmed to move the robot.
High and Low signals are given to control the motor.
FORWARD
Left and right motor rotates in same direction.
Pins 3,5,6,11 are given HIGH, LOW respectively.
Now the robot moves forward.
BACKWARD
Left and right motor rotates in a direction opposite to forward action.
Pins 3,5,6,11 are given LOW,HIGH respectively.
Robot moves backward.
RIGHT
The left motor has to move forward and right motor has to reverse.
Pins 3,5 are given HIGH,LOW and 6,11 are given LOW,HIGH.
Robot turns right.
LEFT
The left motor has to move backward and right motor has to forward.
Pins 3,5 are given LOW,HIGH and 6,11 are given HIGH,LOW.
Robot turns right.
7
Obstacle Avoider Sample Program
Below is the program for Obstacle avoider robot. Click the button and upload it in the SP Duino Board. Watch Video for clarifications.
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