🚀 go-pugleaf

In article <1992Aug12.171255.13584@morgan.ucs.mun.ca>, raghu@morgan.ucs.mun.ca (Raghu B) writes:
|> Can any one tell me any reference books are any valuable materials,
|> from where I can find the singular points for a PUMA-560 arm.
|> I know that they are the extreme ends of the workspace. But
|> I don't know how to find those values. Is there any algorithm
|> or any set of equations which can be solved to get those arm
|> joint angles theta1, theta2 and theta3.
|> 
|> 	Any kind of help is highly appreciated.
|> 
|> 
|> 				Raghu .B


There are singularities which occur at the limits of the workspace.  These
values occur when sin(theta3) = 0, as discussed in the DeMers followup.

However, this arm geometry (called the _articulated_arm_) also has internal
workspace singularities.  An easy way to find these singularities is to 
examine the plane formed by the axes of rotation of the first two joints.
This (vertical) plane passes through the shoulder center, and rotates with
theta1.  Any time the controlled point on the forearm lies in this plane, the
arm is also singular.  Usually this "controlled point" is the center of the
wrist, but it could be any point in space attached to this link.  You cannot
move the controlled point horizontally in this plane at these singularities.

Steve
-- 

Steve Remis 
PhD Student
University of Notre Dame
sremis@tolstoy.helios.nd.edu