Slow strong prismatic joint
Hi.
I'm having some problems modelling a slow and strong prismatic joint (real world screw joint). The problem seems to be that <velocity>
is not being considered.
My joint looks like:
<xacro:macro name="small_extender" params="name rot:=1">
<xacro:small_ext name="${name}_inner" />
<xacro:small_ext2 name="${name}_outer" rot="${rot}" />
<joint name="${name}" type="prismatic">
<parent link="${name}_inner" />
<child link="${name}_outer" />
<axis xyz="0 0 1" />
<origin xyz="0 0 ${small_ext_height - 0.026}" />
<limit
lower="-0.025" upper="0.0"
effort="100.0" velocity="0.00045" />
<dynamics damping="1.0" friction="80" />
</joint>
<gazebo reference="${name}">
<implicitSpringDamper>1</implicitSpringDamper>
</gazebo>
</xacro:macro>
And I'm controlling the joint through a Gazebo plugin that uses JointController
and a position PID with SetPositionTarget
. Currently I'm using <pid>10000.0 0 0 </pid>
for parameters because the distance is quite small. When I set a position target for this joint it moves a lot faster than the <velocity>
tag indicates, and it seems to be the case however I tune the PID. The rest of the robot should have the correct masses so I don't think that is the problem.