Book excerpt: For readers of Robot Building for Beginner (Apress, 2002 and 2009), welcome to the next level. Intermediate Robot Building, Second Edition offers you the kind of real-world knowledge that only renowned author David Cook can offer. In this book, you’ll learn the value of a robot heartbeat and the purpose of the wavy lines in photocells. You’ll find out what electronic part you should sand. You’ll discover how a well-placed switch can help a robot avoid obstacles better than a pair of feelers. And you’ll avoid mistakes that can cause a capacitor to explode. Want a robot that can explore rooms, follow lines, or battle opponents in mini-sumo? This book presents step-by-step instructions and circuit and part descriptions so that you can build the robot featured in the book or apply the modules to your own robot designs. Finally, you’ll find the complete schematics for Roundabout, a room explorer that requires no programming and uses only off-the-shelf electronics. With Roundabout, you’ll use many of the same techniques used by professional robotics engineers, and you’ll experience many of the same challenges and joys they feel when a robot “comes to life.”