http://bugs.orocos.org/show_bug.cgi?id=1010

Summary: weighted positional solver ( ChainIkSolverPos_NR_JL_WE

)

Product: KDL

Version: unspecified

Platform: All

OS/Version: All

Status: NEW

Severity: enhancement

Priority: P3

Component: Kinematic Solvers

AssignedTo: orocos-dev [..] ...

ReportedBy: jelleferinga [..] ...

Estimated Hours: 0.0

Created attachment 842

--> http://bugs.orocos.org/attachment.cgi?id=842

pibgeus ChainIkSolverPos_NR_JL_WE implementation

An old thread on ROS [1] discussed the need for a position IK solver than takes

weighting into account.

Another thread on orocos-users [2] confirmed this need.

A preliminary version has been contributed by pibgeus, though there are issues

with this implementation, as pointed out by Erwin Aertbelien:

============ ==================

pibgeus talks about weights on xyz RPY but in the code the weights are on the

displacement twist (i.e. the result of KDL's diff(..) )

You should also be sure to use a weighted inv. vel. kin.

However, this would not completely solved the problems with the 5 dof robots,

since the weights are still

a diagonal matrix. With these type of weights you cannot specify that the

rotation along a given axes is irrelevant.

You'll need a full symmetric matrix ( or its square root) to specify such a

thing. And even with a full symmetric matrix

it will be annoying to use (because you have to construct the weighing matrix

and that requires some insight).

Better would be in this case to be able to specify the weighing matrix relative

to the end effector.

==============================

[1] http://ros-users.122217.n3.nabble.com/IK-with-KDL-td1867716.html

[2] http://www.orocos.org/forum/orocos/orocos-users/help-5-dof-arm