no factory exists problem with Gazebo ros control tutorial

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Hi there,

My ros distribution is indigo and my ubuntu distribution is 14.04.

I'm currently learning ros control. And it speed learning curve really makes me frustrated.

Here is my question, I tried the Gazebo ros control tutorial at http://gazebosim.org/tutorials/?tut=r... .

When typing "roslaunch rrbot_control rrbot_control.launch" it worked at the first time. But things get weird when I come back several days later( Accurately yesterday..... ). I got errors when loading the control_plugin.

But when I call the service as the third error suggested I find the effort_controllers/JointPositionController exist. And when I type "rospack find effort_controllers" I can find the package under ros/indigo/share/ Furthermore at file effort_controller_plugins.xml it actually contain:

<class> name="effort_controllers/JointPositionController" type="effort_controllers::JointPositionController" base_class_type="controller_interface::ControllerBase"> <description> The JointPositionController tracks position commands. It expects a EffortJointInterface type of hardware interface. </description> </class>

I try to remove and re-install the effort_controllers use "apt-get" several times but the errors still exist.

Please help me out of this.

Thanks in advance. Erli