That sort of query looks right. �It will give you the latest available transform from the "/threemouse" frame_id to the�"/sr_arm/position/shadowarm_handsupport" frame. �Without more information on the setup of your tf frames I cannot say if you're getting the right transform. �I will note that "/"s in frame_ids do not scope the same way as namespaces. If you post the output of view_frames I can help you more. � �

Tully

On Tue, Sep 21, 2010 at 7:08 AM, Ugo Cupcic <ugo@shadowrobot.com> wrote:

�Hey,

I'm trying to implement some reverse kinematics on a custom arm, in
order to move the arm using a 3D mouse.

I want to compose 2 transforms: my 3D mouse is publishing tf transforms,
and I have the tf published by the robot_state_publisher for my arm. I
just want to get the resulting transform: move from the current position
to the current position to the new position (current position +
transform from the mouse).

I was using this but I think it doesn't do what I want.
� � � �tf_listener.lookupTransform("/threedmouse",
"/sr_arm/position/shadowarm_handsupport", ros::Time(0), transform);

Sorry if it's a trivial question :S

Cheers,

Ugo

--
Ugo Cupcic � � � � | �Shadow Robot Company | ugo@shadowrobot.com
Software Engineer �| � �251 Liverpool Road |
need a Hand? � � � | � �London �N1 1LX � � | +44 20 7700 2487
http://www.shadowrobot.com/hand/ � � � � � � �@shadowrobot

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Tully Foote
Systems Engineer
Willow Garage, Inc.
tfoote@willowgarage.com
(650) 475-2827