Hi, I suggest turning up the torque limits, up about 2/3rd way before sim goes unstable is probably where you'll get the better instantaneous response. John
On Fri, Apr 2, 2010 at 7:38 PM, David Michal <[email protected]>wrote: > I have already turned the torque way down and experimented with changing > the masses. I added the additional parameters you suggested as well. > Unfortunately it didn't really change much. The best that I have been > able to do so far is to keep the velocity low. In my particular case it > would be better if I could turn some of the physics off for just the > robot's wheels and have it behave more like it does in Stage. I have > done some experimentation with Microsoft Robotics Developer Studio as > well. When I modeled the same robot there, they recommended that the > wheels should just be set to a given velocity instead of having the > physics engine try to compute their behavior. > > On Thu, 2010-04-01 at 12:58 -0700, Nate Koenig wrote: > > Hello, > > > > You can reduce the torque parameter, and play with the masses. > > > > You can also modify the friction of the wheels. To do this add a the > > following parameters to a geom: > > > > <geom ...> > > <kp>100000000</kp> > > <kd>1.0</kd> <!-- Damping constraint --> > > <bounce>0.0</bounce> <!-- How bouncy the surface is --> > > <bounceVel>10</bounceVel> <!-- MAx velocity before bounce is applied > --> > > <mu1> BIG NUMBER </mu1> > > <mu2> BIG NUMBER </mu2> > > <slip1> small number (0.01) </slip1> > > <slip2> small number (0.01)</slip2> > > </geom> > > > > The ODE manual has descriptions of all these parameters. > > > > -nate > > > > On Sun, Mar 28, 2010 at 9:41 PM, David Michal <[email protected]> > wrote: > > > I have modeled a differential drive robot in Gazebo. The problem is > > > that when I driver the robot from Player it seems to have quite a bit > of > > > inertia. When turning to the left or the right it overshoots the target > > > quite a bit. The real robot uses stepper motors so that once you tell > > > it to stop turning it does. Is there a way to get Gazebo to better > > > model a stepper motor? I am using Player 3.0.1, Gazebo 0.9.0, and ODE > > > 0.11.1. > > > > > > Here is what I have in the model file. > > > > > > <body:cylinder name="left_wheel_body"> > > > <xyz>0.0 0.1325 -0.2032</xyz> > > > <rpy>0 90 90</rpy> > > > <geom:cylinder name="left_wheel_geom"> > > > <size>.0635 .032</size> > > > <mass>0.5</mass> > > > <visual> > > > <rpy>0 0 90</rpy> > > > <size>0.127 0.127 0.032</size> > > > <mesh>drivewheel.mesh</mesh> > > > <material>Gazebo/Black</material> > > > </visual> > > > </geom:cylinder> > > > </body:cylinder> > > > > > > <body:cylinder name="right_wheel_body"> > > > <xyz>0.0 -0.1325 -0.2032</xyz> > > > <rpy>0 90 90</rpy> > > > <geom:cylinder name="right_wheel_geom"> > > > <size>.0635 .032</size> > > > <mass>0.5</mass> > > > <visual> > > > <rpy>0 0 90</rpy> > > > <size>0.127 0.127 0.032</size> > > > <mesh>drivewheel.mesh</mesh> > > > <material>Gazebo/Black</material> > > > </visual> > > > </geom:cylinder> > > > </body:cylinder> > > > > > > <joint:hinge name="left_wheel_joint"> > > > <body1>left_wheel_body</body1> > > > <body2>chassis_body</body2> > > > <anchor>left_wheel_body</anchor> > > > <anchorOffset>0 0 0</anchorOffset> > > > <axis>0 1 0</axis> > > > <erp>0.8</erp> > > > <cfm>10e-5</cfm> > > > </joint:hinge> > > > > > > <joint:hinge name="right_wheel_joint"> > > > <body1>right_wheel_body</body1> > > > <body2>chassis_body</body2> > > > <anchor>right_wheel_body</anchor> > > > <anchorOffset>0 0 0</anchorOffset> > > > <axis>0 1 0</axis> > > > <erp>0.8</erp> > > > <cfm>10e-5</cfm> > > > </joint:hinge> > > > > > > <controller:differential_position2d name="controller1"> > > > <leftJoint>right_wheel_joint</leftJoint> > > > <rightJoint>left_wheel_joint</rightJoint> > > > <wheelSeparation>0.265</wheelSeparation> > > > <wheelDiameter>0.127</wheelDiameter> > > > <torque>1</torque> > > > <interface:position name="position_iface_0"/> > > > </controller:differential_position2d> > > > > > > > > > > > > > ------------------------------------------------------------------------------ > > > Download Intel® Parallel Studio Eval > > > Try the new software tools for yourself. Speed compiling, find bugs > > > proactively, and fine-tune applications for parallel performance. > > > See why Intel Parallel Studio got high marks during beta. > > > http://p.sf.net/sfu/intel-sw-dev > > > _______________________________________________ > > > Playerstage-gazebo mailing list > > > [email protected] > > > https://lists.sourceforge.net/lists/listinfo/playerstage-gazebo > > > > > > > > ------------------------------------------------------------------------------ > > Download Intel® Parallel Studio Eval > > Try the new software tools for yourself. Speed compiling, find bugs > > proactively, and fine-tune applications for parallel performance. > > See why Intel Parallel Studio got high marks during beta. > > http://p.sf.net/sfu/intel-sw-dev > > _______________________________________________ > > Playerstage-gazebo mailing list > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/playerstage-gazebo > > > > > > > ------------------------------------------------------------------------------ > Download Intel® Parallel Studio Eval > Try the new software tools for yourself. Speed compiling, find bugs > proactively, and fine-tune applications for parallel performance. > See why Intel Parallel Studio got high marks during beta. > http://p.sf.net/sfu/intel-sw-dev > _______________________________________________ > Playerstage-gazebo mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/playerstage-gazebo > ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ Playerstage-gazebo mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/playerstage-gazebo
