Hi,
Thanks, when I play with kp and kd, I can prevent the ball from sinking. Now
another thing what is different from my ball model and yours:
Is it right that you set the parameters of a ball with a radius of 0.02 as
follows:
<size>0.02</size>
<visual>
<size>0.04 0.04 0.04</size>
</visual>
When I check this in my gazebo-simulation, it seems to be right. But in your
model you use: <scale> instead of <size>, is this right?
It's really weird because the examples use both (simpleshapes.world /
pioneer2dx.world).
Thanks,
Rein
here is a sample ball model I'm using for my simulations. Notice the
> <kd> and <kp> params and try to play with their values - they control
> how much force
> is applied to this specific ball model to prevent it from sinking:
>
> <body:sphere name = "ball_body">
> <dampingFactor>0.0001</dampingFactor>
> <xyz>0 0 0</xyz>
> <rpy>0 0 0</rpy>
> <geom:sphere name = "ball_geom">
> <xyz>0 0 0.01</xyz>
> <rpy>0 0 0 </rpy>
> <size>0.02</size>
> <mu1>0.3</mu1>
> <kp>2e6</kp>
> <kd>2e6</kd>
> <bounce>120</bounce>
> <bounceVel>0.5</bounceVel>
>
> <slip1>0.7</slip1>
> <slip2>0.7</slip2>
>
> <mass>0.045</mass>
> <visual>
> <scale>0.02 0.02 0.02</scale>
> <mesh>unit_sphere</mesh>
> <material>Gazebo/Robocup_orange</material>
> </visual>
> </geom:sphere>
> </body:sphere>
>
>
> Also global parameters like step time, erp and cfm does matter, I'm
> using those values:
> <stepTime>0.002</stepTime>
> <erp>0.9</erp>
> <cfm>0.01</cfm>
>
> I hope that will help you,
>
> Best regards,
> Kamil Muszyński
>
>
> 2011/6/9 Rein Appeldoorn <rein...@gmail.com>:
> > I checked those two parameters but nothing changes. Is this a known fact
> or
> > is this just something weird? Here is the world file I'm using:
> >
> >
> -----------------------------------------------------------------------------------
> >
> > <?xml version="1.0"?>
> >
> > <gazebo:world
> > xmlns:xi="http://www.w3.org/2001/XInclude";
> > xmlns:gazebo="http://playerstage.sourceforge.net/gazebo/xmlschema/#gz
> "
> > xmlns:model="
> http://playerstage.sourceforge.net/gazebo/xmlschema/#model";
> >
> > xmlns:sensor="
> > http://playerstage.sourceforge.net/gazebo/xmlschema/#sensor";
> > xmlns:window="
> > http://playerstage.sourceforge.net/gazebo/xmlschema/#window";
> > xmlns:param="
> http://playerstage.sourceforge.net/gazebo/xmlschema/#param";
> >
> > xmlns:body="http://playerstage.sourceforge.net/gazebo/xmlschema/#body
> "
> > xmlns:geom="http://playerstage.sourceforge.net/gazebo/xmlschema/#geom
> "
> > xmlns:joint="
> http://playerstage.sourceforge.net/gazebo/xmlschema/#joint";
> >
> > xmlns:interface="
> > http://playerstage.sourceforge.net/gazebo/xmlschema/#interface";
> > xmlns:ui="http://playerstage.sourceforge.net/gazebo/xmlschema/#ui";
> > xmlns:rendering="
> > http://playerstage.sourceforge.net/gazebo/xmlschema/#rendering";
> > xmlns:controller="
> > http://playerstage.sourceforge.net/gazebo/xmlschema/#controller";
> > xmlns:physics="
> > http://playerstage.sourceforge.net/gazebo/xmlschema/#physics"; >
> >
> > <verbosity>5</verbosity>
> >
> > <physics:ode>
> > <stepTime>0.005</stepTime>
> > <gravity>0 0 -9.8</gravity>
> > <cfm>0</cfm>
> > <erp>0.8</erp>
> > <quickStep>true</quickStep>
> > <quickStepIters>100</quickStepIters>
> > <quickStepW>1.3</quickStepW>
> > <contactMaxCorrectingVel>100.0</contactMaxCorrectingVel>
> > <contactSurfaceLayer>0.0</contactSurfaceLayer>
> > <updateRate>0</updateRate>
> > </physics:ode>
> >
> > <rendering:gui>
> > <type>fltk</type>
> > <size>800 600</size>
> > <pos>0 0</pos>
> > </rendering:gui>
> >
> > <rendering:ogre>
> > <ambient>0.8 0.8 0.8 1.0</ambient>
> > <sky>
> > <material>Gazebo/CloudySky</material>
> > </sky>
> > <grid>false</grid>
> > <shadowTechnique>stencilModulative</shadowTechnique>
> > </rendering:ogre>
> >
> > <!-- The Ground Plane -->
> > <model:physical name="groundplane_model">
> > <xyz>0 0 0</xyz>
> > <rpy>0 0 0</rpy>
> > <static>true</static>
> >
> > <body:plane name="ground_plane_body">
> > <geom:plane name="ground_plane_geom">
> > <normal>0 0 1</normal>
> > <size>1000 1000</size>
> > <segments>100 100</segments>
> > <uvTile>100 100</uvTile>
> > <material>Gazebo/GrassFloor</material>
> > <mu1>109999.0</mu1>
> > <mu2>1000.0</mu2>
> > </geom:plane>
> > </body:plane>
> > </model:physical>
> > <!-- End Ground Plane -->
> >
> > <!-- The Ball Model -->
> > <model:physical name="ball_model">
> > <xyz>0.025 0 1</xyz>
> > <static>false</static>
> >
> > <body:sphere name="ball_body">
> > <geom:sphere name="ball_geom">
> > <xyz>0 0 0</xyz>
> > <size>0.015</size>
> > <mass>0.02</mass>
> >
> > <visual>
> > <size>0.03 0.03 0.03</size>
> > <mesh>unit_sphere</mesh>
> > <material>Gazebo/White</material>
> > </visual>
> > <mu1>109999.0</mu1>
> > </geom:sphere>
> > </body:sphere>
> > </model:physical>
> > <!-- End Ball Model -->
> >
> >
> > <!-- The White Point light -->
> > <model:renderable name="point_white">
> > <xyz>-3 0 5</xyz>
> > <static>true</static>
> > <light>
> > <type>point</type>
> > <diffuseColor>0.8 0.8 0.8</diffuseColor>
> > <specularColor>0.1 0.1 0.1</specularColor>
> > <range>20</range>
> >
> > <!-- Constant(0-1) Linear(0-1) Quadratic -->
> > <attenuation>0.3 0.01 0</attenuation>
> > </light>
> > </model:renderable>
> > <!-- End White Point light -->
> >
> > </gazebo:world>
> >
> >
> -----------------------------------------------------------------------------------
> >
> > Do you guys get the same behavior? If so, is there any fix or a way to
> get
> > rid of this?
> >
> > Thanks in advance!
> >
> > Rein
> >
> > On Wed, Jun 8, 2011 at 8:33 PM, John Hsu <john...@willowgarage.com>
> wrote:
> >
> >> Hi,
> >>
> >> you can check to see if contactSurfaceLayer is small, e.g.
> >>
> >> <contactSurfaceLayer>0</contactSurfaceLayer>
> >>
> >> in addition, you might want to make sure <CFM> is 0.
> >>
> >> hope this helps.
> >>
> >> John
> >>
> >> On Wed, Jun 8, 2011 at 11:00 AM, Rein Appeldoorn <rein...@gmail.com>
> >> wrote:
> >>
> >> > Hi,
> >> >
> >> > I'm working on a simulation of an autonomous football table. When I
> model
> >> > the ball, it's sinking through the floor. Because the geometry of the
> >> ball
> >> > is quite small (radius of 0.015), this sinking is not acceptable.
> Strange
> >> > enough, when I check the other objects, they're all sinking a little
> bit.
> >> > Does anybody have an explanation for this?
> >> >
> >> > A thing I can do is scale up all models, this makes the relative
> errors
> >> > much
> >> > less. Does anybody got experience with this fact? Is scaling a good
> >> > solution?
> >> >
> >> > Thanks in advance!
> >> >
> >> > Regards,
> >> >
> >> > Rein
> >> >
> >> >
> >>
> ------------------------------------------------------------------------------
> >> > EditLive Enterprise is the world's most technically advanced content
> >> > authoring tool. Experience the power of Track Changes, Inline Image
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> >> > _______________________________________________
> >> > Playerstage-gazebo mailing list
> >> > Playerstage-gazebo@lists.sourceforge.net
> >> > https://lists.sourceforge.net/lists/listinfo/playerstage-gazebo
> >> >
> >>
> >>
> >>
> >> --
> >> John Hsu, Ph.D.
> >> Senior Research Engineer
> >> Willow Garage Inc.
> >> +1-650-475-2809
> >>
> >>
> ------------------------------------------------------------------------------
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> >>
> >
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