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motoman_mh50_support URDF frame location

asked 2019-05-26 09:08:59 -0500

nd gravatar image

updated 2019-05-27 04:25:16 -0500

Hello, link text In motoman_mh50_support URDF distance between joint_6_t and tool0 is 0.175m also we can see in CAD model.

<link name="${prefix}link_6_t">
    <visual>
        <geometry>
            <mesh filename="package://motoman_mh50_support/meshes/visual/mh50_link_6_t.stl"/>
        </geometry>
        <material name="yaskawa_blue"/>
    </visual>
    <collision>
        <geometry>
            <mesh filename="package://motoman_mh50_support/meshes/collision/mh50_link_6_t.stl"/>
        </geometry>
    </collision>
</link>
<link name="${prefix}tool0"/>

.............................................................................................

<joint name="${prefix}joint_6_t" type="revolute">
    <parent link="${prefix}link_5_b"/>
    <child link="${prefix}link_6_t"/>
    <origin xyz="0 0 0" rpy="0 0 0" />
    <axis xyz="-1 0 0" />
    <limit lower="-6.2831" upper="6.2831" effort="333.43" velocity="6.283"/>
</joint>
<joint name="${prefix}joint_6_t-tool0" type="fixed">
    <origin xyz="0.175 0 0" rpy="3.1415926 -1.570796 0"/>
    <parent link="${prefix}link_6_t"/>
    <child link="${prefix}tool0"/>
</joint>

But when I see in RVIZ, why there is some gap in last tool0 frame location? this frame location should be at last link, why there is some gap? or am I understanding wrong?

link of RVIZ image, link text

thanks.

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1 Answer

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answered 2019-05-26 18:27:09 -0500

Geoff gravatar image

There are several possible reasons:

  • The tool's origin is offset that much from the end of the physical part of the previous link due to some extension part, such as an attachment plate that effectively becomes part of the previous link by moving with that link, not with the tool.
  • The STL file that is used to display link_6_t is slightly shorter than the real part.
  • The offset in the URDF for the tool's origin is incorrect.

If you have access to the real robot, I suggest measuring the offset of the tool link's moving part and seeing if it matches the URDF file. If you don't, then try adding the URDF for a tool to the Motoman URDF and seeing if the moving part of the tool has its origin correctly aligned with the rest of the arm.

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Comments

This might actually just be a mistake made when creating the meshes.

@nd: if it appears the kinematics are OK, then I would suggest you post an issue over at the motomanissue_tracker.

gvdhoorn gravatar image gvdhoorn  ( 2019-05-27 02:23:21 -0500 )edit

done......

nd gravatar image nd  ( 2019-05-27 04:26:05 -0500 )edit

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Asked: 2019-05-26 09:08:59 -0500

Seen: 29 times

Last updated: May 27 '19