Building Robots With Lego Mindstorms

284 Chapter 15 • Building Robots That Walk

The same robot can stay balanced even with just two legs, because the COG

still falls inside the supporting base (Figure 15.6).

When the robot advances the two lifted legs, part of its mass moves forward,

and the COG moves forward a bit, too. But the large contact surfaces of the legs

delimit a zone wide enough to make the COG fall within the boundaries (see

Figure 15.7).

Using more than four legs, you don’t need to rely on their size anymore.A

six-legged robot, for example, can walk with very thin feet provided it always has

at least three of them touching the ground (Figure 15.8).

On the contrary, when reducing ...