App Inventor

Chapter 12. NXT Remote Control

In this chapter, you’ll create an app that turns your Android phone into a remote control for a LEGO MINDSTORMS NXT robot. The app will have buttons for driving the robot forward and backward, turning left and right, and stopping. You’ll program it so the robot automatically stops if it detects an obstacle. The app will use the Bluetooth capabilities of the phone to communicate with the robot.

LEGO MINDSTORMS robots are fun to play with, but they are also educational. After-school programs use robots to teach elementary- and middle-school children problem-solving skills and introduce them to engineering and computer programming. NXT robots are also used by kids aged 9–14 in FIRST Lego League robotics competitions.

The NXT programmable robotics kit includes a main unit called the NXT Intelligent Brick. It can control three motors and four input sensors. You can assemble a robot from LEGO building elements, gears, wheels, motors, and sensors. The kit comes with its own software to program the robot, but now you can use App Inventor to create Android applications to control an NXT using Bluetooth connectivity.

The application in this chapter is designed to work with a robot that has wheels and an ultrasonic sensor, such as the Shooterbot robot pictured here. The Shooterbot is often the first robot that people build with the LEGO MINDSTORMS NXT 2.0 set. It ...