[proposal] Add class for single link model.

[snozawa]

This PR is just a proposal to add class for single link model
(related with @furushchev dinner discussion).
This is originally from https://github.com/jsk-ros-pkg/jsk_demos/blob/master/jsk_2015_06_hrp_drc/drc_task_common/euslisp/drc-testbed-models.l#L9.

This is used for creating single rigid body object model.

In this PR, I added single-link-model class, but I think adding function to create single link model is another solution.

@furushchev
FYI, in euslisp, robot models and object models should be defined as cascaded-link class (or its subclass).

• historical situation
  Even if simple shape (like make-cube) and single rigid body object,
  it would be better to define it as cascaded-link instead of body or bodyset class.
  In euslib/rbrain, object models were defined as both robot-object (old style object model class) and body or bodyset class.
  It was very confusing.
  Since used methods are quite different between robot-object and body, some codes for robot-object did not work for body and it was difficult to generalize codes.
• definition
  In euslisp, body, bodyset, faceset, ... classes have geometric shape information.
  bodyset-link class has shape information and mass information and this class corresponds to so cold link in robotics fields.
  cascaded-link class includes links, joints, and some other semantic information and this class corresponds to robot and object.
  So, it would be better to define object model as cascaded-link class.
  The codes in this PR may be minimal codes to define cascaded-link class with single link.

[k-okada]

how abut add link/joint keyward option in init method of cascaded-link ?

◉ Kei Okada

On Fri, Dec 11, 2015 at 11:58 PM, Shunichi Nozawa [email protected]
wrote:

This PR is just a proposal to add class for single link model
(related with @furushchev https://github.com/furushchev dinner
discussion).
This is originally from
https://github.com/jsk-ros-pkg/jsk_demos/blob/master/jsk_2015_06_hrp_drc/drc_task_common/euslisp/drc-testbed-models.l#L9
.

This is used for creating single rigid body object model.

In this PR, I added single-link-model class, but I think adding function
to create single link model is another solution.

@furushchev https://github.com/furushchev
FYI, in euslisp, robot models and object models should be defined as
cascaded-link class (or its subclass).

historical situation
Even if simple shape (like make-cube) and single rigid body object,
it would be better to define it as cascaded-link instead of body or
bodyset class.
In euslib/rbrain, object models were defined as both robot-object (old
style object model class) and body or bodyset class.
It was very confusing.
Since used methods are quite different between robot-object and body,
some codes for robot-object did not work for body and it was difficult
to generalize codes.

definition
In euslisp, body, bodyset, faceset, ... classes have geometric shape
information.
bodyset-link class has shape information and mass information and this
class corresponds to so cold link in robotics fields.
cascaded-link class includes links, joints, and some other semantic
information and this class corresponds to robot and object.
So, it would be better to define object model as cascaded-link class.
The codes in this PR may be minimal codes to define cascaded-link
class with single link.

---

You can view, comment on, or merge this pull request online at:

#321
Commit Summary

• [irteus/irtrobot.l] Add class for single link model.

File Changes

• M irteus/irtrobot.l
  https://github.com/euslisp/jskeus/pull/321/files#diff-0 (21)

Patch Links:

• https://github.com/euslisp/jskeus/pull/321.patch
• https://github.com/euslisp/jskeus/pull/321.diff

—
Reply to this email directly or view it on GitHub
#321.

[snozawa]

Thanks.
Current needs is functionality to generate an object model from list of body or bodyset.
This is not necessary, but convenient functionality.

how abut add link/joint keyward option in init method of cascaded-link ?

In this case, this corresponds to add :bodies argument for cascaded-link and
generate cascaded-link instance with a single link and no joints.
Is this OK?

[k-okada]

please provide us an example code

◉ Kei Okada

On Sun, Dec 13, 2015 at 7:22 PM, Shunichi Nozawa [email protected]
wrote:

Thanks.
Current needs is functionality to generate an object model from list of
body or bodyset.
This is not necessary, but convenient functionality.

how abut add link/joint keyward option in init method of cascaded-link ?

In this case, this corresponds to add :bodies argument for cascaded-link
and
generate cascaded-link instance with a single link and no joints.
Is this OK?

—
Reply to this email directly or view it on GitHub
#321 (comment).

[snozawa]

I provide :bodies argument version:

(defmethod cascaded-link
  (:init (&rest args
                &key name
                     ((:bodies bs))
                &allow-other-keys)
         "Create cascaded-link."
         (send-super-lexpr :init args)
         (when bs
           (push (instance bodyset-link :init (make-cascoords)
                           :bodies bs :name :root-link)
                 links)
           (send self :assoc (car links)))
))

Example code:

(setq *obj* (instance cascaded-link :init :bodies (list (make-cube 100 100 100) (make-cylinder 40 200))))
(send *obj* :init-ending)
(objects (list *obj*))

Original example in this PR method:

(setq *obj* (instance single-link-model :init :bodies (list (make-cube 100 100 100) (make-cylinder 40 200))))
(objects (list *obj*))