Appendix B
06/2005
Danaher Motion
176 Rev
E
M-SS-005-03
In these cases, world-space is identical to joint-space. Each coordinate of the joint-space
vector is directly translated into a coordinate of world-space.
In groups with the robot model defined (model > 1), the translation between joint- and world-
space is much more complex. Translating joint coordinates into world coordinates is
accomplished with
TOCART
taking both the robot and given joint coordinates (position
variable) as input arguments. The output of this is world coordinates corresponding to the
given joint position.
The other direction is more complex. It is accomplished with
TOJOINT
receiving three input
arguments: the robot, the given Cartesian point, and the configuration flag.
The configuration flag is used to select between the two translation functions. In most robot
models, there is more than one joint coordinate description for the same world-space
position. The different robot configurations can produce the same world-space positions with
different joint-space values. The robot configurations differ from robot to robot. In SCARA,
there are only two configurations: lefty (second joint coordinate is negative) and righty
(second joint coordinate is positive).
Interpolation
For groups with robot models (model > 1), there is an additional moving type:
MOVES
. The
movement makes a straight path from the starting position to the given target position in the
world space. The straightness is tightly-related to the working space. The same path can be
straight in the Cartesian working space (XYZ) but curvy in joint space, and vice versa.
MOVES
is used solely for groups from type robot and cannot be used in regular groups.
Straight line motion refers to motions that are straight lines in world-space. In groups with no
robot model (model=1), all motions produced with
MOVES
are straight-line motions in joint-
space. In regular linearly-dominant groups, most of their axes are linear. As the world-space
and joint-space are identical,
MOVES
executes a straight line in both joint- and world-space.
The target position can be given both in world- and joint-space coordinates. The movement
differs from joint interpolation (
MOVE
). Instead of joint-space kinematics parameters used in
regular groups, the world-space parameters for velocity, acceleration and jerk are used.
These parameters are available in two forms:, one for the translational part of the motion and
one for the rotational part (orientation).
When world-space has both position and orientation components, the straight-line motion
includes interpolation on both position and orientation. Because these two are intrinsically
different objects, two different parameters are needed: one for the translation (pure position
interpolation):
VELOCITYTRANS
,
ACCELERATIONTRANS
,
JERKTRANS
; and one for
the orientation (rotation interpolation):
VELOCITYROT
,
ACCLERATIONROT
,
JERKROT
.
These parameter are used only for Cartesian interpolation (
MOVES
and
CIRCLE
). These
parameters have no influence on joint interpolated motion (
MOVE
) because it is not a world-
space interpolation.
The two sets of parameters define the straight line motion. Which parameter is dominant for
the motion depends on the movement. If most of the movement is in translational position
change and the orientation change is much smaller, the translational part is taken.
Conversely, the rotational parameters define the movement.
