[irtgeo.l] enable :rotation-axis :xy :yz :zx :yx :zy :xz by Naoki-Hiraoka · Pull Request #568 · euslisp/jskeus

Naoki-Hiraoka · 2020-05-24T02:00:57Z

I enabled :rotation-axis :xy :yz :zx :yx :zy :xz for :inverse-kinematics.

$ (setq *robot* (instance sample-robot :init))
$ (send *robot* :rarm :inverse-kinematics (make-coords :pos #F(300 -200 100)) :rotation-axis :xz)
$ (send *robot* :rarm :end-coords :difference-rotation (make-coords :pos #F(300 -200 100)))
#f(0.528315 0.000625 -0.138705) ;;only Y component is almost zero

iory · 2020-05-24T20:27:19Z

irteus/irtgeo.l

  (:difference-rotation
   (coords &key (rotation-axis t))
-   "return difference in rotation of given coords, rotation-axis can take (:x, :y, :z, :xx, :yy, :zz, :xm, :ym, :zm)"
+   "return difference in rotation of given coords, rotation-axis can take (:x, :y, :z, :xy, :yz, :zx, :xx, :yy, :zz, :xm, :ym, :zm)"


How about adding :yx :zy :xz?

The documentation of :difference-position does not have :yx :zy :xz.
I made the documentation of :difference-rotation similar to :difference-position.

jskeus/irteus/irtgeo.l

Lines 56 to 58 in 8902642

(:difference-position

(coords &key (translation-axis t))

"return difference in position of given coords, translation-axis can take (:x, :y, :z, :xy, :yz, :zx)."

I see.
But rotation-axis, the argument of :difference-rotation, can take :yx, :zy, :zx. This is clear from your commit. c3603fe#diff-23ea0c1757d7ef177d46886dd7b78a15R91

I think that good documentation supports other users. So how about changing the document of difference-position?

It ’s true. I fixed. 85c060d
Thank you!

…rotation

iory · 2020-05-25T02:32:18Z

irteus/irtgeo.l

              (transform (transpose (send self :worldrot))
                         (scale (acos (v. a0 a1)) (normalize-vector (v* a0 a1))))))
+       ((:xy :yx :yz :zy :zx :xz)
+        (setq a0 (send self :axis (case rotation-axis ((:xy :yx) :z) ((:yz :zy) :x) ((:zx :xz) :y)))


How about use 'let'. The following code is my suggestion.

((:xy :yx :yz :zy :zx :xz) (let ((ax1 (case rotation-axis ((:xy :yx) :z) ((:yz :zy) :x) ((:zx :xz) :y))) (ax2 (case rotation-axis ((:xy :yx) :x) ((:yz :zy) :y) ((:zx :xz) :z)))) (setq a0 (send self :axis ax1) a1 (send coords :axis ax1)) (setq dif-rot (transform (transpose (send self :worldrot)) (scale (acos (v. a0 a1)) (normalize-vector (v* a0 a1))))) (let ((self-coords (send (send self :copy-worldcoords) :rotate (norm dif-rot) dif-rot))) (setq a0 (send self-coords :axis ax2) a1 (send coords :axis ax2)) (setq dif-rot (transform (transpose (send self-coords :worldrot)) (scale (acos (v. a0 a1)) (normalize-vector (v* a0 a1))))))))

Thank you. I fixed. 815f8b4

k-okada

please improve documentation/examples at https://github.com/euslisp/jskeus/blob/master/doc/irtmodel.tex#L1903-L1921

k-okada · 2020-05-26T10:37:51Z

Thank you for contributing jskeus documentation

Please check latest documents before merging

PDF version of Japanese jmanual: jmanual.pdf
HTML version of Japanese manual: jmanual.html
Sphinx (ReST) version of Japanese manual: jmanual.rst

Naoki-Hiraoka · 2020-05-26T10:41:17Z

In 85d63f9 , I added documentation

jskeus/doc/irtmodel.tex

Lines 1608 to 1609 in 9a271ed

    
           \verb|t|は三軸拘束，\verb|nil|は拘束なし，その他に\verb|:x|, 
        
           \verb|:y|, \verb|:z|を指定することができる．

jskeus/doc/irtmodel.tex

Lines 1608 to 1610 in 85d63f9

    
           \verb|t|は三軸拘束，\verb|nil|は拘束なしを示し，その他に拘束なしの軸を 
        
           エンドエフェクタの座標系で\verb|:x|, \verb|:y|, \verb|:z|, \verb|:xy|, 
        
           \verb|:yz|, \verb|:zx|と指定することができる．

This PR cannot improve the example at
https://github.com/euslisp/jskeus/blob/master/doc/irtmodel.tex#L1903-L1921
because the goal condition of this example is that ''Z axis of target-coords is on XZ plane of move-target'', and rotation-axis is not enough to represent such a complicated condition.

k-okada · 2020-05-26T10:56:35Z

Thank you for contributing jskeus documentation

Please check latest documents before merging

PDF version of Japanese jmanual: jmanual.pdf
HTML version of Japanese manual: jmanual.html
Sphinx (ReST) version of Japanese manual: jmanual.rst

Naoki-Hiraoka · 2020-05-27T04:46:18Z

There are few cases where this new feature is effective, but it certainly exists.
I heard this new feature is effective in @takayuki5168 's case.
@takayuki5168 Do you have good examples?

takayuki5168 · 2020-05-28T12:02:22Z

Sorry to be late. I think this PR is partly effective when the robot grasps the cylinder.
Here is an example that PR2 grasps the cylinder using :yz.

(load "package://pr2eus/pr2-interface.l")
(pr2)

(setq *obj* (make-cylinder 30 300))
(send *obj* :move-to (make-coords :pos #f(500 -300 700) :rpy #f(1 2 3)))

(objects (list *pr2* *obj*))

(let ((target-coords (send (send *obj* :copy-worldcoords) :locate #f(0 0 150))))
  (send *pr2* :rarm :inverse-kinematics target-coords
        :rotation-axis :yz)
  )

takayuki5168 · 2020-05-28T12:05:04Z

This picture shows the result when we execute above code, which means using yz.

The following figures are when using :y and :z respectively.

Naoki-Hiraoka · 2020-05-29T01:41:48Z

ありがとうございます．
こちらのケースも，
https://github.com/euslisp/jskeus/blob/master/doc/irtmodel.tex#L1903-L1921
のケースと同様に，①"target-coordsのZ軸をmove-targetのXZ平面上に位置させる"という問題です．
このような問題は多い気がします．
例えば，X軸方向に長い鉄パイプを把持しているときに，それを水平に持って運びたいという場合，②"move-targetのX軸を，target-coords(world系)のXY平面上に位置させる"という問題になります．

~~①②それぞれのケースを:rotation-axis的に表現すると，~~
~~①は"target-coords系Z軸まわりとmove-target系Y軸まわりの回転エラーを許容する"~~
~~②は"move-target系X軸まわりとtarget-coords系Z軸まわりの回転エラーを許容する"~~
~~となります．~~

~~したがって，これらのケースに対応するためには，今回のpull requestに加えて，~~
:rotation-axisの各軸ごとにどの座標系で評価するのかを指定できるようにする必要があると思いました．(現在の:inverse-kinematicsは全てmove-target座標系で評価しています)

Naoki-Hiraoka · 2020-05-29T02:48:00Z

:rotation-axis :z: 回転エラーの角軸ベクトルのZ軸以外の成分をゼロにする
:rotation-axis :yz: 回転エラーの角軸ベクトルのZ軸Y軸以外の成分をゼロにする
という解釈でこのpull requestを作りましたが，

:rotation-axis :z: move-targetのZ軸とtarget-coordsのZ軸を一致させる拘束を加える
:rotation-axis :yz: move-targetのY軸とtarget-coordsのZ軸を直交させる拘束を加える(:zyと:yzは意味が異なる)(move-targetのZX平面とtarget-coordsのZ軸を一致させる拘束や，move-targetのY軸とtarget-coordsのXY平面を一致させる拘束と等価)
という解釈で作り直すべきかもしれません．

takayuki5168 · 2020-05-29T09:21:40Z

なるほど，確かにmove-targetのY軸とtarget-coordsのZ軸が直交するのとmove-targetのZ軸とtarget-coordsのY軸が直交するのは違うね．

このPRの実装だと円柱の把持のIKができないという認識であってるよね？上記のPR2の例はたまたまよさげだけど．とすると，平岡くんの解釈でPRを作りなおすのが良い気がする．

Naoki-Hiraoka · 2020-05-29T10:07:32Z

その通りです．
実用上のケースを考えると，
「回転エラーの角軸ベクトルのZ軸Y軸以外の成分をゼロにする」という解釈で役に立つことはまれなので，
円柱を掴む場合などに便利な「move-targetのY軸とtarget-coordsのZ軸を直交させる拘束」を意味するように作り直します．

[irtgeo.l] enable :rotation-axis :xy :yz :zx :yx :zy :xz

c3603fe

iory reviewed May 24, 2020

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[irtgeo.l] fix documentation of :difference-position and :difference-…

85c060d

…rotation

iory approved these changes May 25, 2020

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iory reviewed May 25, 2020

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[iregeo.l :difference-rotation] use let, and fix 0 norm condition

815f8b4

iory approved these changes May 25, 2020

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k-okada reviewed May 26, 2020

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[doc/irtmodel.tex]add document for translation/rotation-axis

85d63f9

Naoki-Hiraoka force-pushed the enable-dual-rotation-axis branch from a484bc1 to 85d63f9 Compare May 26, 2020 10:49

k-okada added the PR/NeedFix label Jun 7, 2020

k-okada added the PR/WaitForExamples label Nov 24, 2021

	(:difference-position
	(coords &key (translation-axis t))
	"return difference in position of given coords, translation-axis can take (:x, :y, :z, :xy, :yz, :zx)."

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