As the name indicates, SLIM-BOT, is a small, simple, compact robot, which may be moved or controlled using various inputs, without using any micro-controller. There is no need of programming language or coding to make and control the Slim-Bot. This is the basic project for those, who don’t have any knowledge in micro-controllers and programming. The various controls for the Slim-Bot is completely based on the electronic circuits only.
To make IR line follower, two sets of, IR (Infra-Red) light emitting LEDs (known as IR-LEDs) and IR sensing LEDs (known as IR sensor LEDs) are used on either side of a line, fitted on the front side of slim-bot. The signal generated by the IR sensor LEDs, based on the presence of the line, is fed to the two digital inputs of the 8 pin berg strip. The Slim-bot moves forward or takes turn accordingly to move itself on the line.
About Infra Red Sensing:
To make the slim-bot compact, two numbers of small IR sensor boards are made for reading the presence of the line. Each IR sensor board contains, an IR-LED and an IR sensor LED, which are positioned side-by-side on a small PCB. Two series resistors and connectors are used for each IR sensor board.
The complete circuit diagram of IR sensor board and actual IR sensor board with IR-LED and IR sensor LED arrangement, are shown below. Similar IR sensor boards are readily available in the market, with sensitivity adjustment, may be used in the project. But, they are little bigger in size.
When, the IR sensor board is connected to power supply (here it is 3.7VDC), then the IR-LED glows, which emits IR (Infra-Red) light. As the IR light is invisible to naked eye, you may use any digital camera (or mobile phone camera), to check the working of IR-LED.
When the IR light is reflected back from a surface (on white surface), the resistance of IR sensor LED is decreased and the voltage at signal junction increases.
About Line Follower:
Two such IR sensor boards are fitted on either side, in front of the slim-bot. The circuit diagram, connecting the two IR sensor boards to the 8 pin berg strip on base board, is shown below.
When, an IR sensor LED gets high signal, due to white surface (reflected IR light from IR-LED), then the motor on the same side rotates. Similarly, when the IR sensor LED gets low signal, due to black surface (insufficient reflected light from IR-LED from black surface), then the motor on the same side stops rotation.
So, the motor on white surface side rotates in forward direction and the motor on black surface side (line is drawn in black colour) stops rotation. Thus, making the slim-bot to re-position on the line. When both the IR sensors are on white surface, the slim-bot moves straight forward, continuously.