Robot Enhancement Circuit: Designed for BOE-Bot Mobile Robot
This circuit is specifically crafted to integrate seamlessly onto the front of the BOE-Bot mobile robot, as detailed in . While it’s adaptable for use with any microcontroller, its design is optimized for connection with the Arduino Nano support board . This support board, precisely sized for the robot, conveniently links to two servomotors via designated connectors. The circuit’s purpose is to empower a mobile robot with the capability to gather information about its immediate surroundings. It achieves this using two microswitches (end-of-travel detectors), two photoresistors, and three infrared proximity detectors. With these sensors, the microcontroller gains crucial data, enabling it to accurately guide the robot by sending appropriate commands to the servomotors.
Fine-Tuning Infrared Detection
The interface circuit for the three infrared detectors adheres to a standard design, as previously utilized in . Potentiometers P1, P2, and P3 offer the flexibility to adjust the current driving the transmitting diodes, dictating the maximum distance at which the detector can sense obstacles. To safeguard the microcontroller from potential short-circuits, 2.2 kΩ resistors are integrated. These resistors protect against accidental shorts that might occur when the microcontroller pin, configured as an output, generates a logic level different from that of the detector.
Obstacle Detection and Track Following
Microswitches play a pivotal role in obstacle detection, ensuring the robot can detect obstacles along its route, thus preventing collisions. When an obstacle is detected, the microswitches force the microcontroller’s input pin low. The two photoresistors facilitate the robot in tracking a reflective path laid out on the ground. Configured strategically, they enable resistance measurement using a single logic input/output: initially, the microcontroller pin operates as an output, set high to discharge the capacitor. Subsequently, when the pin transitions to an input state, the capacitor charges through the photoresistor, causing the pin to shift from logic 1 to logic 0. The time it takes for this transition, proportional to the RC time constant, provides a measurement of the photoresistor’s value, representing the intensity of the light falling on it.
Expansion Possibilities with Additional Board
For added flexibility, an expansion board with a quick prototyping area simplifies connections between the Arduino Nano support board and supplementary circuits, including an electronic compass, real-time clock, math co-processor, and accelerometer functioning as an inclinometer. Further details, including test sketches and the PCB design for the additional expansion board, can be accessed on the article’s webpage .
Internet links Basic Stamp Programming Course, Elektor, September–December 1999.  www.elektor.com/100396  Basic Buggy, Elektor, April 1999.  www.elektor.com/100395