Page 264 - Concise Encyclopedia of Robotics

Quadtree
on the surface at the vertices of a well-defined triangle. In these examples,
the solid dots represent feet on the ground; the open circle represents the
foot that is lifted at the moment.
Many engineers believe that six legs is optimal for robots designed to
propel with legs rather than by rolling on wheels or a track drive. Six-
legged robots can lift one or two legs at a time while walking and remain
stable. The more legs a robot has, the better its stability; but there is a
practical limit.The movements of robot legs must be coordinated properly
for a machine to propel itself without wasting motion and energy. This
becomes increasingly difficult as the number of legs increases.
See also INSECT ROBOT and ROBOT LEG.
QUADTREE
A quadtree is a scheme in which a two-dimensional (2-D) rectangular
occupancy grid can be divided into smaller and smaller subelements, as
necessary to define a function to a desired level of resolution. The illustra-
tion shows a simple example. In this case, the robot’s work environment
(or world space) is shown by the largest square. This square is divided into
four square subelements. The upper left subelement is in turn split
2
into four square sub-subelements (or sub -elements); the lower right

Quadtree

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