In the new armnavigation stack, it looks like one has to setup a planning scene even if no obstacles are checked. In the file pr2armkinematicsconstraint_aware.cpp:106, function PR2ArmIKConstraintAware::isReady, the code reads:

if(!collision_models_interface_->isPlanningSceneSet()) {
    ROS_INFO("Planning scene not set");
    error_code.val = error_code.COLLISION_CHECKING_UNAVAILABLE;
    return false;
}

This code gets called when I use the ikutilities function runik, with a collision free check.

So why does pr2armkinematicsconstraintaware always need a scene to be set?