Households with large lawns usually have a lot of problem in cutting the grass and maintaining it. Garduino is a rover specifically built for this purpose. It can autonomously navigate the garden, cut the grass and dump them in a place so that compost can be made from it. There are 3 ultrasonic sensors attached to the Garduino which will help it navigate the garden by maintaining a fixed distance from the wall. A motor is placed in the front of the rover which has blades attached to it. So, wherever the rover goes, it cuts the grass and drags them to the dump areas in the garden.

Step 1: Components Required

Arduino UNO R3x 1
USB cable x 1
Ultrasonic Sensor x 3
3V DC BO Motor 300RPM x 2
Motor Driver Board (L293D IC Based) x 1
Caster Wheel x 1
Wheels x 2
9V Battery Pack ( 6 AA Cells) x 1
Single Core Wire (2 Colours, 1mtr each) x 2
470Ω Resistor x 3
Breadboard x 2
3V DC Motor with Propeller x 1
Printed Circuit Board (PCB) x 1
Connecting Wires (Male to Female) x 20
Connecting Wires (Male to Male) x 20

Note: Mi-Bot kit can be purchased from ebay:

http://www.ebay.in/itm/MiBOT-Arduino-Robotic-Kit-w...

Step 2: Construction of Mi-Bot

A detailed instructable on the construction of Mi-Bot is available on:

https://www.instructables.com/id/Construction-Man...

Step 3: Circuit Connections of Mi-Bot

Motor Driver:

A motor driver is a module that helps in the operation of certain motors at variable speeds by providing a separate power source other than that from the microcontroller. This protects the microcontroller/ microprocessor from the current surges initiated by the motor. This module consists of a common 3 Male headers which corresponds to +9V/+12V, GND and +5V. The +9V or +12V supply is used to power the motor. +5V is used to operate the L293D IC. This motor driver module can handle a maximum of 2 motors. For each motor, 2 pins are used to receive signals from the microcontroller/microprocessor and 2 pins are used to connect the DC motor.

Few precautions:
Always ensure and re-check the wiring (against circuit design), before powering up the board.

Circuit Connections:

Connect the two terminals of the left Motor to the Left Screw Header pins of the Motor Driver Board.
Repeat the same for the Right Motor also.
Connect M1.A to Digital Pin 3 using Male to Female Connecting Wire.
Connect M1.B to Digital Pin 5 using Male to Female Connecting Wire.
Connect M2.A to Digital Pin 6 using Male to Female Connecting Wire.
Connect M2.B to Digital Pin 9 using Male to Female Connecting Wire.
Take one Male to Female Connecting Wire and Connect the Female side of the wire to +5V Terminal of the Motor Driver Board.
Connect the other terminal to the Breadboard as shown in the circuit.
Take one Male to Male connecting wire and connect one end to 5V Pin on the Arduino UNO and the other terminal on the breadboard where the wire was connected in the last step.
Take one Male to Female connecting Wire and connect the Female side of the wire to GND terminal of the Motor Driver Board.
Connect the other terminal to the Breadboard as shown in the circuit.
Take one Male to Male connecting wire and connect one end to GND Pin on the Arduino UNO and the other terminal on the Breadboard where the wire was connected in the last step.
Now take the 9V (6AA Cells) Battery pack and connect its Positive terminal to the +12V terminal of the motor Driver.
Connect the negative terminal of the 9V battery to the Breadboard where GND is connected.

Step 4: Interfacing Ultrasonic Sensor With Arduino

Ultrasonic Sensor:

An Ultrasonic sensor is a device that can measure the distance to an object by using sound waves. It measures distance by sending out a sound wave at a specific frequency and listening for that sound wave to bounce back. By recording the elapsed time between the sound wave being generated and the sound wave bouncing back, it is possible to calculate the distance between the sonar sensor and the object.

Pin Configuration:

VCC: 5V DC Power supply
Trig: trigger signal for starting the transmission with 10µs high time
Echo: Output
GND: Ground

Calculating the distance of an object from the Ultrasonic Sensor

Since it is known that sound travels through air at about 344m/s (1129 ft/s), you can take the time for the sound wave to return and multiply it by 344 meters (or 1129 feet) to find the total round-trip distance of the sound wave. Round-trip means that the sound wave travelled 2 times the distance to the object before it was detected by the sensor; it includes the 'trip' from the ultrasonic sensor to the object and the 'trip' from the object to the Ultrasonic sensor (after the sound wave bounced off the object). To find the distance to the object, simply divide the round-trip distance in half.

Circuit Connections:

Connect the ultrasonic sensor (1) Trig pin to the digital pin 7 on the Arduino using male to female connecting wire.
Connect the ultrasonic sensor (1) Echo pin to the digital pin 8 on the Arduino using male to female connecting wire.
Connect the ultrasonic sensor (2) Trig pin to the digital pin 10 on the Arduino using male to female connecting wire.
Connect the ultrasonic sensor (2) Echo pin to the digital pin 11 on the Arduino using male to female connecting wire.
Connect the ultrasonic sensor (3) Trig pin to the digital pin 9 on the Arduino using male to female connecting wire.
Connect the ultrasonic sensor (3) Echo pin to the digital pin 2 on the Arduino using male to female connecting wire.
Take a male to male wire, connect 1 terminal to the 5V pin on the Arduino and the other terminal of the wire to the breadboard.
Connect the VCC pins of the ultrasonic sensors to the 5V pin of the Arduino through the breadboard as shown in the figure.
Take a male to male wire, connect 1 terminal to the GND pin on the Arduino and the other terminal of the wire to the breadboard.
Connect the GND pins of the ultrasonic sensors to the GND pin of the Arduino through the breadboard as shown in the figure.

Step 5: Interfacing Motor With Arduino

DC motor:

This is a High rpm DC motor. These motors contain two wires which enables the motor to rotate in either in clockwise or anti - clockwise direction.

Note: Here, the motor is directly connected to the Arduino Board because the motor which is used here does not draw much current. It is always recommended to connect the motor via motor Driver Board (L293D IC Based) and power it up using external Power supply to prevent the board from damaging.