Electronics

This early version of the robot includes a single L298N motor driver that gives power to the two front wheels and is controlled by the Arduino Uno.

Here I present how the motor controller is connected to the Arduino and source code for controlling the motors.

The robot has two ultra sound sensors to stop the robot from running into people and other objects that could be inside the perimiter wire area.

Here I present how the two ultra sound sensors are connected to the Arduino and source code for how to detect objects.

To power the Arduino from the 18V battery you need a DC step down converter that needs to step down the voltage to lower than 12V.

Here I present how the DC step down converter is connected to the battery and to the Arduino power in port.

In the robot back electronic box I have placed two L298N motor drivers. One is for the two front wheels and the other is for the grass cutting motor.

I will go in to details about how the battery is connected to the motor driver and how the driver is connected to the cutter DC motor and the source code to control the cutter.

The Perimeter wire station is a quite simple system using a Arduino Uno connected to a L298N motor driver to send out a 5KHz square pulse on the wire. The motor driver is powered by a 12V battery and connected to the perimeter wire via two 10 ohm resistors and two 10µF capacitor to create a pulse that the pulse sensor on the robot can detect.

The robot has two perimeter pulse sensors. The sensor consist of a coil that builds up a charge when being placed close to a wire with a changing electric charge (perimeter wire pulse). The two coils are placed on each side of the robot front and are each connected to a LM358 operation amplifier with the output connected to a analog input on the Arduino.