Difference between revisions of "XML format description"

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== SSSP ==
 
== SSSP ==
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The surfaces supporting stable placements are specified by 4 values (''xmin, xmax, ymin, ymax'') representing a rectangular region '''in the reference frame of the object'''.  
+
The surfaces supporting stable placements are specified by 6 values (''xmin, xmax, ymin, ymax, zmin, zmax'') representing a rectangular region '''in the reference frame of the object'''.  
 
<syntaxhighlight  lang="xml" line="line">
 
<syntaxhighlight  lang="xml" line="line">
 
<sssp>
 
<sssp>
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</syntaxhighlight>
 
</syntaxhighlight>
  
 +
<u>Remarks:</u>
 +
* In stacking problems, the SSSP is defined by a single point centred on top of the object (i.e., ''xmin=xmax, ymin=ymax'') therefore objects will be aligned on top of each other (e.g., ''disc2'' and ''disc3'' in the example below).
 +
* The number of SSSP per object is currently limited to one. This assumes that if an object is rotated about the x or y axis, it is no longer possible to place something on it. This assumption is sufficient for the current set of benchmark problems, but it may be relaxed later, i.e., by allowing lists of SSOP.
 +
* For non trivial shapes, a list of points defining a polygon may be used later on.
 +
 +
== SOP ==
 +
The stable object poses are defined similarly to continuous grasps: a template rotation and a rotation axis (both expressed '''in the world frame of reference''', plus the ''distance'' parameter, which is the distance between the centre of the object and the SSSP.
 
<syntaxhighlight  lang="xml" line="line">
 
<syntaxhighlight  lang="xml" line="line">
 
<sop>
 
<sop>
 
   <template>1.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 1.0</template>
 
   <template>1.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 1.0</template>
 
   <axis>0.0 0.0 1.0</axis>
 
   <axis>0.0 0.0 1.0</axis>
 +
  <distance>0.08</distance>
 
</sop>
 
</sop>
 
</syntaxhighlight>
 
</syntaxhighlight>
−
 
−
In the example below, the SSSP of ''disc2'' and ''disc3'' boils down to a single point because it is assumed that the discs should be perfectly aligned when stacked on top of each other. The SSSP of ''table'' is a rectangular area matching the position and dimensions of the surface of the table.
 
−
<br />
 
−
<br />
 
−
<u>Remark:</u> A list of points defining a polygon may be used later for non trivial shapes.
 
−
 
−
== SOP ==
 
−
The stable object poses are defined similarly to continuous grasps: a template rotation and a rotation axis (both expressed '''in the world frame of reference'''.
 
−
<br />
 
 
<br />
 
<br />
−
<u>Remark:</u> SSSP and SOP tags are simple xml nodes in the example, but we could aim at something more general and define them as lists. In this way, we could approximate non-square SSSP by several rectangles (or polygons), and similarly allow for several SOP for objects (upright, upside-down, lying on the side). (to be discussed)
+
<u>Remark:</u> Several SOP can be defined for one object, to represent, e.g., SOP in upright position and SOP in up-side-down position.
  
 
== Initial object attachments ==
 
== Initial object attachments ==

Revision as of 17:51, 19 February 2018

The following describes the format used to wrap the geometric information describing the problem single XML file. Meshes, kinematic models and task domain/problem are given in separate files. The xml file contains information about the initial geometric state, and invariants such as grasps, surfaces supporting stable placements, stable objects poses, movability, initial attachments.

General structure

The file is overall structured as follows: 

 1 <problem>
 2    <objects>
 3       object1
 4       object2
 5       ...
 6    </objects>
 7 
 8    <robots>
 9       robot1
10       robot2
11       ...
12    </robots>
13 </problem>

Grasps, SSSP, and SOP are relative to objects, therefore object description follows the following template: 

 1 <obj>
 2    <name>obj1_name</name>
 3    <geom>filename.obj</geom>
 4    <pose>...</pose>
 5    <moveable>true/false</moveable>
 6    <grasps>
 7       <gf>...</gf> and/or
 8       <gc>...</gc> 
 9    </grasps>
10    <sssp>...</sssp>
11    <sop>...</sop>
12    <attachments>...</attachments>
13 </obj>

Parameters

All numerical values are expressed in standard units: meters (distances) and radians (angles).

Single values

Example: 

<torso>0.15</tordo>

The initial value for the torso joint is 15cm.

Vectors

Vectors are used for 3D vectors (e.g., rotation axis), but also to specify robot configurations (e.g., arm configurations).

Examples: 

<axis>0.0 0.0 1.0</axis>
<left_arm>0.5 0.0 0.0 -0.16 0.0 -0.11 0.0</left_arm>

Transformation matrices

Transformation matrices are used to represent the initial poses of objects, or the initial pose of a robot's base. A 3x4 transformation matrix Tmatrix.gif

is represented by a 12-uplet (row-wise) as follow:

<tag>a0 a1 a2 a3 b0 b1 b2 b3 c0 c1 c2 c3</tag>

Grasps

Grasps can be specified in two ways:

  • discrete set of grasps: a list of grasp frames (<gf>...</gf>)
  • continuous set of grasps: a template grasp and a rotation axis (<gc>...</gc>)

Xml attributes are used to specify grasp types (up to the TMP planner to use it or not): 

<gf type="top_grasp">0.0 0.0 1.0 -0.0015 0.0 -1.0 0.0 0.027 1.0 0.0 0.0 -0.051</gf>
<gf type="side_grasp">0.0 0.0 1.0 -0.005 0.0 1.0 0.0 0.005 -1.0 0.0 0.0 0.123</gf>

In the case of continuous grasps, a template frame and a rotation axis are given: 

<gc type="top_grasp">
   <template>0.0 0.0 1.0 -0.0015 0.0 -1.0 0.0 0.027 1.0 0.0 0.0 -0.051</template>
   <axis>0.0 0.0 1.0</axis>
</gc>

Any number/type of grasps can be combined within a <grasps>...</grasps> tag.
They refer to the object in which they are declared.

SSSP

The surfaces supporting stable placements are specified by 6 values (xmin, xmax, ymin, ymax, zmin, zmax) representing a rectangular region in the reference frame of the object. 

1 <sssp>
2    <xmin>-0.25<xmax><xmin>0.25<xmax>
3    <ymin>-0.25<ymax><ymin>0.25<ymax>
4    <zmin>0.5<zmax><zmin>0.5<zmax>
5 </sssp>

Remarks:

  • In stacking problems, the SSSP is defined by a single point centred on top of the object (i.e., xmin=xmax, ymin=ymax) therefore objects will be aligned on top of each other (e.g., disc2 and disc3 in the example below).
  • The number of SSSP per object is currently limited to one. This assumes that if an object is rotated about the x or y axis, it is no longer possible to place something on it. This assumption is sufficient for the current set of benchmark problems, but it may be relaxed later, i.e., by allowing lists of SSOP.
  • For non trivial shapes, a list of points defining a polygon may be used later on.

SOP

The stable object poses are defined similarly to continuous grasps: a template rotation and a rotation axis (both expressed in the world frame of reference, plus the distance parameter, which is the distance between the centre of the object and the SSSP. 

1 <sop>
2    <template>1.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 1.0</template>
3    <axis>0.0 0.0 1.0</axis>
4    <distance>0.08</distance>
5 </sop>


Remark: Several SOP can be defined for one object, to represent, e.g., SOP in upright position and SOP in up-side-down position.

Initial object attachments

Although this is not allowed in this problem, if disc2 was moved, disc1 would also move, just as a tray with objects on it. We can represent this as a list tied to the "parent" object.

Example

Example for problem1 (disc3 and pegs omitted for clarity). 

 1 <problem>
 2    <objects>
 3 
 4       <obj>
 5          <name>disc1</name>
 6          <geom>cylinder1.obj</geom>
 7          <pose>1.0 0.0 0.0 0.7 0.0 1.0 0.0 0.2 0.0 0.0 1.0 0.028)</pose>
 8          <moveable>true</moveable>
 9          <grasps>
10             <!-- discrete set of grasps for that object -->
11             <gf>0.0 0.0 1.0 -0.0015 0.0 -1.0 0.0 0.027 1.0 0.0 0.0 -0.051</gf>
12             <gf>0.0 0.0 1.0 -0.0015 0.0 1.0 0.0 0.0 -1.0 0.0 0.0 0.051</gf>
13             .....
14          </grasps>
15          <sssp>false</sssp> <!-- no sssp for disc1 -->
16          <sop>
17             <template>1.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 1.0</template> <!-- all z-rotations of the -->
18             <axis>0.0 0.0 1.0</axis>                                 <!-- "natural" position     -->
19          </sop>
20          <attachments>false</attachments> <!-- nothing attached to disc1 -->
21       </obj>
22 
23       <obj>
24          <name>disc2</name>
25          <geom>cylinder2.obj</geom>
26          <pose>1.0 0.0 0.0 0.7 0.0 1.0 0.0 0.2 0.0 0.0 1.0 -0.038)</pose>
27          <moveable>true</moveable>
28          <grasps>
29             <!-- continuous set of grasps for that object -->
30             <gc>
31                <template>0.0 0.0 1.0 -0.0015 0.0 -1.0 0.0 0.027 1.0 0.0 0.0 -0.051</template>
32                <axis>0.0 0.0 1.0</axis>
33             </gc>
34          </grasps>
35          <sssp> <!-- sssp = single point -->
36             <xmin>0.0<xmax><xmin>0.0<xmax>
37             <ymin>0.0<ymax><ymin>0.0<ymax>
38             <zmin>0.065<zmax><zmin>0.065<zmax>
39          </sssp>
40          <sop>
41             <template>1.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 1.0</template> <!-- all z-rotations of the -->
42             <axis>0.0 0.0 1.0</axis>                                 <!-- "natural" position     -->
43          </sop>
44          <attachments> <!-- disc1 attached to disc2 -->
45             <name>disc1</name>
46          </attachments>
47       </obj>
48 
49       ...
50 
51       <obj>
52          <name>table</name>
53          <geom>table_narrow.obj</geom>
54          <pose>1.0 0.0 0.0 0.9 0.0 1.0 0.0 -0.4 0.0 0.0 1.0 -0.87)</pose>
55          <moveable>false</moveable>
56          <sssp> <!-- sssp = horizontal rectangular region -->
57             <xmin>-0.68<xmax><xmin>0.0<xmax>
58             <ymin>0.0<ymax><ymin>0.83<ymax>
59             <zmin>0.78<zmax><zmin>0.78<zmax>
60          </sssp>
61          <sop>false</sop> <!-- does not really apply to the table (moveable=false) -->
62          <attachments> <!-- does not apply, but for the sake of example -->
63             <name>peg1</name>
64             <name>peg2</name>
65             <name>peg3</name>
66             <name>disc3</name>
67          </attachments>
68      </obj>
69 
70       ...
71 
72    </objects>
73 
74    <robots>
75       <robot>
76          <name>pr2</name>
77          <urdf>models/pr2.urdf</urdf> <!-- or some other format -->
78          <basepose>1.0 0.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 0.0 1.0 0.0)</basepose>
79          <movebase>false</movebase> <!-- in problems 1 and 2, the base should not move -->
80          <torso>0.1</torso>
81          <left_arm>0.5 0.0 0.0 -0.16 0.0 -0.11 0.0</left_arm>
82          <right_arm>-0.5 0.0 0.0 -0.16 0.0 -0.11 0.0</right_arm>
83       </robot>
84    </robots>
85 
86 </problem>
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