the project

LCD

The LCD works in 4-bit mode, so it uses four data pins plus 2 extra pins for RS and Enable.
(RW pin is wired to ground)

The LCD is used to display a simple menu where you can check things like:

• Select the mode: Line following or Exploring mode.

• Battery Voltage

• Servo test

• The front side IR sensor

• Display the distance from Ultrasonic sensor in cm.

FRONT SIDE IR SENSORS

These sensors help to detect the obstacles in the exploring mode. They are made from double layer copper board. On the board you can see 2 IR transsmiter diodes, with a IR receiver diode on the middle, some SMD limiting current resistors connectet in parallel to the transmitters and SMD led to indicate when the obstacle is detected.

The output of the IR receiver goes through a wire to the main board, and the both IR receivers (left and right side) are connected to the comparator on main board. 
From comparator logic signals (high/low) go straight to the PIC microcontroller.

FRONT LINE FOLLOWING IR SENSOR

This sensor can be used in two modes, line following mode or in exploring mode.

In exploring mode it helps to detect a small bright obstacles located on the floor.
It is made from two dual comparators, and three tcrt5000 IR sensors. The idea of how it works is exactly the same as in previous sensor.

This sensor is made from two PCBs, the first PCB is actually for holding the sensor and it is mountet on a hinge (I found this hinge in and old unused video player).

I used it to change the position of the sensor, for line following it goes down and for exploring it goes up. You can see it on the photos.