Page 90 - The Definitive Guide to Building Java Robots

Preston_5564C03.fm Page 71 Wednesday, October 5, 2005 7:21 AM

CHAPTER 3 ■ MOTION 71

• JMotion.java: The interface that defines the basic movements of all types of motion (for
wheeled and legged robots)
• SpeedDiffDrive.java: The extended version of TimedDiffDrive that gives speed control to
any motion
The next type of motion is still going to be done with servos, but this time it will move
something on your robot rather than the robot itself. It will rely on the same principles
discussed here but instead of creating methods like forward() or pivotRight(), it will create
methods like lookUp() or lookRight() to move a camera.

3.3 Pan and Tilt Mechanisms

Sometimes you just want to move part of your robot. If you have a camera and are doing some
things with machine vision (see Chapter 6), then you definitely want a pan and tilt camera
system. The one I use is shown in Figure 3-7 and comprises a few brackets and two servos,
which can be purchased from Lynxmotion for less than $35. I will take the same concepts used
in our differential drive systems like grouping servos together in a class, and then we will use
our MiniSSC class to control the servos.

Figure 3-7. The Lynxmotion Pan and Tilt Kit

Figure 3-8 shows a diagram that summarizes the classes.