What Is A Robot; Mobile Robots - LEGO MINDSTORMS Robots Manual

This is a book about creating robots with the LEGO® MINDSTORMS™ Robotic Invention System (RIS)™. If you've always dreamed of building and programming your own robots, this is your
big chance—the RIS set makes it easy to get started. There are a lot of enthusiastic RIS owners out there already: other people have built robots that pick up empty soda cans; robots that seek light;
robots that play tag; walking robots with two, four, six, or even eight legs; robots that can be controlled over the Internet; working computer peripherals like a plotter and an optical scanner; and
robots that simulate a Tsunami and a tornado.∗ You can build anything you can imaging. RIS gives you a chance to breathe life into LEGO creations, making them move and respond to their
surroundings. You can create a tank that scurries into the dark, or a monorail car that traverses your living room on a string. You can create robots that hop, walk, and drive around with a mind of
their own.
Furthermore, by owning the RIS set, you become part of a worldwide community of enthusiasts. The RIS set is a common ground for building robots; if you build something cool, other people
will be able to build it too. Similarly, you can build and modify other people's creations. LEGO bricks, therefore, are a kind of lingua franca for mechanical design.
You have many options when it comes to building and programming robots. LEGO bricks, of course, can be assembled in many different ways. Part of this book is about building robots; it
includes five projects that you can build yourself. But you also have lots of options for programming your robot. Aside from the "official" software that comes with RIS, the inventive
MINDSTORMS community
∗ Internet links to pictures of some of these robots are included in the "Online Resources" section at the end of this chapter.
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has produced a bevy of other options. The most important ones are described in this book.
This chapter describes the basic concepts of robotics and creates a backdrop for the MINDSTORMS product line. I'll also cover different approaches to programming mobile robotics. Finally, I'll
describe the RIS set itself. If you're in a hurry to start building something, skip ahead to Chapter 2, Hank, the Bumper Tank.

What Is a Robot?

A robot is a machine whose behavior can be programmed. This is a broad definition—it includes things like VCRs and microwave ovens, a far cry from the talking androids you might be thinking
of. Robots have five fundamental components:
1. A brain controls the robot's actions and responds to sensory input. Usually the brain is a computer of some kind.
2. A robot's body is simply the physical chassis that holds the other pieces of the robot together.
3. Actuators allow the robot to move. These are usually motors, although there are many other possibilities, such as hydraulic pistons.
4. Sensors give a robot information about its environment. A touch sensor, for example, can tell a robot that it has come in contact with something else.
The last component is not always obvious:
5. A power source supplies the juice needed to run the brain, actuators, and sensors.
For example, think about a robot that spraypaints cars in a factory. Its brain is probably a garden-variety desktop computer. The body is a big arm with a paint sprayer at the end. The actuators are
motors or pneumatic pistons that move the arm around. Position and rotation sensors are used so the robot knows where the sprayer is and what direction it's pointing. The whole thing is plugged
into a wall socket for power.

Mobile Robots

Mobile robots present special challenges. These robots can move their bodies around from place to place. Why is this capability difficult? Many more things can go wrong if your robot is free to
move around rather than being bolted to one place. Being mobile multiplies the number of situations your robot needs to be able to handle.