“…The key feature of HIL is that all algorithms must be tested in close-to-reality simulators or real-world environments so as to make re-optimization possible [15]. For simulation, we adopt Gazebo [10], [12], a high-fidelity robotic evaluation platform that adopts Open Dynamics Engine for motion generation of the robots and Open Graphics Library Engine for the visualization of the world. On top of the two engines, Gazebo realizes each physical object as a model that is composed of rigid bodies, joints, sensors, and interfaces for client programs to control the model.…”