1. Ando, N., Suehiro, T., Kitagaki, K., Kotoku, T. and Yoon, W. K., RT-middleware: distributed component middleware for RT (robot technology), Proceedings of the IEEE/RSJ International Conference on Intelligent Robots and Systems (2005), pp.3555-3560.
2. Åström, K. J. and Hägglund, T., PID Controllers: Theory, Design, and Tuning 2nd Edition (1995), pp.80-92, Instrument Society of America.
3. Baerveldt, A. J. and Klang, R., A low-cost and low-weight attitude estimation system for an autonomous helicopter, Proceedings of the IEEE International Conference on Intelligent Engineering Systems (1997), pp.391-395.
4. DARPA, The DARPA Robotics Challenge (2015), available from <http://archive.darpa.mil/roboticschallenge/>, (accessed on 16 September, 2017).
5. Fareastgizmos, Hubo the first robot in the world to get on a Segway (2007), available from <http://fareastgizmos.com/other_stuff/hubo_the_first_robot_in_the_world_to_get_on_a_segway.php>, (accessed on 16 September, 2017).