strange pitch direction
Hello! I have some troubles understanding rpy. Here is my simple URDF file:
<robot name="test">
<link name="Body">
<inertial>
<mass value="4.0" />
<origin xyz="1 0 0"/>
<inertia ixx="1" ixy="1" ixz="1" iyy="1" iyz="1" izz="1" />
</inertial>
<visual>
<geometry>
<box size="0.1 0.02 0.02"/>
</geometry>
</visual>
</link>
<link name="link1">
<inertial>
<mass value="4.0" />
<origin xyz="1 0 0"/>
<inertia ixx="1" ixy="1" ixz="1" iyy="1" iyz="1" izz="1" />
</inertial>
<visual>
<geometry>
<box size="0.1 0.02 0.02"/>
</geometry>
</visual>
</link>
<joint name="j1" type="revolute" >
<parent link="Body"/>
<child link="link1"/>
<origin xyz="0.1 0 0" rpy="0 -0.5 0" />
<axis xyz="1 0 0"/>
<limit lower="-1.57" upper="1.57" effort="10" velocity="10"/>
</joint>
</robot>
As you see, there are two links with a revolute joint between them. There is a pitch of -0.5 radians in the joint. And here is the rviz image :
The question is why link1
is rotated upwards instead of downwards?