Should inherit from SubRobot.hpp, which can be found in the itasc_core. This file is a template for a robot or object component. See itasc_robots_objects stack for examples.

As can be seen in the examples, a robot component contains always a KDL::Tree, even if the robot is just a chain. This is to be able to use the KDL::Tree functionality, which is regrettable, not perfectly similar as the KDL::Chain functionality. E.g. tree.getSegment(string name) has a string as input, chain.getSegment(number) has a number as input, but not a string...