Understanding the ros_control packages

The ros_control packages have the implementation of robot controllers, controller managers, hardware interfaces, different transmission interfaces, and control toolboxes. The ros_controls packages are composed of the following individual packages:

• control_toolbox: This package contains common modules (PID and Sine) that can be used by all controllers
• controller_interface: This package contains the interface base class for controllers
• controller_manager: This package provides the infrastructure to load, unload, start, and stop controllers
• controller_manager_msgs: This package provides the message and service definition for the controller manager
• hardware_interface: This contains the base class for the hardware interfaces
• transmission_interface: This package contains the interface classes for the transmission interface (differential, four bar linkage, joint state, position, and velocity)