Hi Konrad,

One of the original goals when designing the pr2_calibration stack was to be
able to support static cameras by simply using "null" kinematic chains
whenever there aren't any joints.  However, after briefly looking at the
code, it looks like I'm assuming a non-null chain in several places.

I'm assuming you've looked at (
http://www.ros.org/wiki/pr2_calibration_estimation)

As a workaround to create a static camera, I'd suggest defining a
pseudo-null chain as follows:

  fake_chain:
   dh:
   - [   0,  0, 0, 0 ]
   cov:
     joint_angles: [1.0]
   gearing: [1.0]

You can then construct a camera chain as follows:

camera_chains:
  - camera_id: my_fixed_cam
    sensor_id: my_fixed_cam
    chain:
      before_chain: [transform1, transform2]
      chain_id:     fake_chain

      after_chain:  []
      dh_link_num:  0


This is definitely a hack, but I think it will get you going.

Also note that even though the stack is designed to work with other robots,
it is not a supported use case, and very few other people (maybe only one
other person) have tried to port pr2_calibration to their robot.  You
shouldn't need to edit a single line of source code to get it working with
your robot, but peeking at the source code might give you some intuition as
to what is going on under the hood.  Don't feel shy about asking more
questions as you go down this road.

Vijay

On Thu, Jan 20, 2011 at 2:16 PM, Konrad Banachowicz <konradb3@gmail.com>wrote:

> Hi,
>
> I would like to calibrate my robot setup.
> My setup is simpler than pr2, contains 6dof manipulator and static cameras.
> I want calibrate positions of cameras and offset of manipulator joints.
> pr2_calibration mostly fit my needs, but pr2_calibration_estimation does
> not provide static camera sensor type. I think that it could be simply
> added, but i am not very familiar with Python and NumPy. Can you provide me
> some instruction how to add (modyfy camera chain) static camera sensor.
>
> Pozdrawiam
> Konrad Banachowicz
>
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>


-- 
Vijay Pradeep
Systems Engineer
Willow Garage, Inc.
 <tfoote@willowgarage.com>vpradeep@willowgarage.com