Table of Contents

1. Building Biped Robots: In this chapter you will learn the complete state of art of the LEGO walking robots developed from 1998 to 2008. You will learn the most used design approaches for biped robots that do not need special sensors to balance.
2. Quasimodo: This is a funny interlacing legs biped that uses an original solution for shifting its center of mass, making it resemble the Hunchback of Notre-Dame. It serves as occasion to discuss the common issues about this kind of bipeds. You will meet NXC, the powerful programming language used throughout the book.
3. State Machines: SM are a software technique to give your robots an autonomous behavior in a simple and effective way. The robots of this book that use SM are the AT-ST biped, the NXT Turtle, and JohnNXT.
4. AT-ST (All Terrain Scout Transport): This chicken-like biped walker is designed after the real AT-ST of the Star Wars movies.  It can walk and turn, avoiding obstacles.
5. Omni-Biped: This is a smooth COG-shifting biped. It brings the inheritance of the Alpha-Rex bipedal walking technique to a higher level. It walks smooth and fast, and can turn on its own footprints.

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6. NXT Turtle: In this chapter you will bring a robotic pet to life! It walks, and retract the head inside the shell. The main topic of the chapter is the implementation of the autonomous behavior for the turtle using FSMs.
7. Mine Sweeper: This robot can detect and collect objects, by scanning the ground. It can safely work on a table thanks to a sensor that detects cliffs.
8. JohnNXT: After huge popular demand, here comes my Johnny 5 replica! This robot features moving treads, rotating head, poseable neck and eyelids, moving torso, underactuated grabbing mechanism and laser. You can use the provided SDK (Software Development Kit) to fully customize its program. Its double-NXT system uses the high speed serial communication on port 4. You can remote control JohnNXT via Bluetooth.
9. Bluetooth Remote: This Bluetooth remote is comfortable, and features two analog joysticks and two triggers. You can remote-control all the robots of this book with it.

JohnNXT neck fix

Problem: JohnNXT resets all the parts with limited movement at program startup. Many readers pointed out an issue about the neck mechanism: the neck would not properly reset, because the motor did not detect the stall correctly.

Solution: Jim Denson (Plainville, MA, USA) suggested this simple yet really effective modification to fix this neck reset problem. Just add a 1×3 Technic liftarm on the neck axle, between the base of the neck and the head. Thanks, Jim. Click on the image to enlarge it.