Design and Implementation of a Line Following Robot with Temperature Sensing and Comparing Capability

Abstract

Line following robot is a kind of robot which can detect a path drawn in a surface. This can be a black line in white surface or white line in a black surface. In this project we made a line following robot which can follow a white line drawn on a black surface. The robot has another feature - the ability to sense the temperature. So, the objective to make this robot is to follow a white line in black surface and also sense the temperature in its path. The robot is programmed so that it can measure temperature in its path at an interval of 30 seconds. The application of this robot is in temperature sensitive areas like cold storage, chemical industries, medicine manufacturing farms etc. In these areas, maintenance of temperature is an important issue, so we can easily use this robot. The principle of detecting the path uses the reflectivity of light. Black surface absorbs light and white surface reflects it. We have used seven LEDs (Light Emitting Diode) and seven LDRs (Light Depending Resistor) to detect the path. An LED and an LDR together make a single sensor circuit. When the sensor is over a white surface, the light from the LED reflects from the surface to the LDR and due to the decrease of resistivity of the LDR, the voltage across the LDR decreases. The output of each sensor circuit works as an input of a comparator (Ie LM324) which compares the output voltage ofLDR to a reference voltage which is given manually. If the LDR output voltage is higher than the reference voltage, then the comparator outputs logic high; otherwise the comparator output is logic low. So the comparator Ie converts the analog signal to digital. As we have used seven sensors to detect path, so we have a combination of seven bits of logical data. Value of this combination always changes during the path following. We use those combinations to the input pins of the microcontroller as the digital data. In our project we have used microcontroller ATmega16A from AVR. The microcontroller gives output (according to the data and the program code) to a motor drive IC.