What values are you using for the PID controller? I'd also love to see what the resulting forces on the joint are. Could you take a bag of the joint_states topics (using rosrecord)? -Stu On Tue, May 11, 2010 at 12:14 AM, Andreas Vogt wrote: > Hi, > > my desired position is constant but the forces of the hole robot are > sometimes to high that they pushing the joint into another position. > > Stuart Glaser schrieb: >> Hi, >> >> The PR2 does not have brakes on its joints.  The best way to keep the >> joint stationary is to use a PID loop, keeping the desired position >> constant (desired_pos_steer[0] in your case). >> >> -Stu >> >> On Mon, May 10, 2010 at 8:22 AM, Andreas Vogt wrote: >> >>> Hi, >>> >>> I control my position of the joints with a PID/force controller(see >>> below). Is it possible to fix the position after the joint reached the >>> goal position like a break would do? >>> >>>  pr2_mechanism_model::JointState* steer1_state; >>>  steer1_state->commanded_effort_ = pos_pid_1.updatePid( >>> current_pos_steer[0]- desired_pos_steer[0], dt); >>> >>> Andreas >>> >>> _______________________________________________ >>> ros-users mailing list >>> ros-users@code.ros.org >>> https://code.ros.org/mailman/listinfo/ros-users >>> >>> >> >> >> >> > > > -- > >  Andreas Vogt >  Logistics and Production Robotics > >  DFKI Bremen >  Robotics Innovation Center >  Robert-Hooke-Straße 5 >  28359 Bremen, Germany > >  Phone: +49 (0)421 218-64140 >  Fax:   +49 (0)421 218-64150 >  E-Mail: andreas.vogt@dfki.de > >  Weitere Informationen: http://www.dfki.de/robotik >  ----------------------------------------------------------------------- >  Deutsches Forschungszentrum fuer Kuenstliche Intelligenz GmbH >  Firmensitz: Trippstadter Straße 122, D-67663 Kaiserslautern >  Geschaeftsfuehrung: Prof. Dr. Dr. h.c. mult. Wolfgang Wahlster >  (Vorsitzender) Dr. Walter Olthoff >  Vorsitzender des Aufsichtsrats: Prof. Dr. h.c. Hans A. Aukes >  Amtsgericht Kaiserslautern, HRB 2313 >  Sitz der Gesellschaft: Kaiserslautern (HRB 2313) >  USt-Id.Nr.:    DE 148646973 >  Steuernummer:  19/673/0060/3 > > _______________________________________________ > ros-users mailing list > ros-users@code.ros.org > https://code.ros.org/mailman/listinfo/ros-users > -- Stuart Glaser sglaser -at- willowgarage -dot- com www.willowgarage.com