Robot Mechanisms and Mechanical Devices Illustrated - Profe Saul

248 Chapter 10 Manipulator Geometries
POLAR OR SPHERICAL
The third, and most versatile, geometry is the
spherical type. In this layout, the work envelope
can be thought of as being all around. In reality,
though, it is difficult to reach everywhere.
There are several ways to layout an arm with
this work envelope. The most basic has a rotating
base that carries an arm segment that can
pitch up and down, and extend in and out
(Figure 10-8). Raising the shoulder up (Figure
10-9) changes the envelope somewhat and is
worth considering in some cases. Figures 10-10,
10-11, and 10-12 show variations of the spherical
geometry manipulator.
Figure 10-8 Basic polar
coordinate manipulator
Figure 10-9 High shoulder
polar coordinate manipulator
with offset joint at elbow