Building Robots With Lego Mindstorms

Finding and Grabbing Objects • Chapter 11 209

construction crane is an example of a machine with three DOFs:The hook can go

up and down, it’s attached to a carriage that moves back and forth along the boom,

and, finally, the boom can rotate.With the three output ports of your RCX, you

can drive a robotic arm that addresses any point inside a delimited space, called the

operating envelope, exactly like the crane of the previous example. If you also want to

pick up and drop objects, you would need another port, or use some of the tricks

from Chapter 9 to control more than a DOF with a single motor.

Finding Objects

Building robotic arms and hands is the ...