本研究旨在整合重心估測與力矩控制提昇雙足機器人行走穩定性。利用三維線性倒單擺模型（3D LIPM）簡化機器人動態模型，並設計以踝關節力矩作為輸入的平衡控制器，考慮實際系統的重心位置會因量測誤差或機器人姿態改變而存在一定的偏差量，若僅回授量測的重心位置，便會因重心有所偏差而使機器人平衡時存在穩態誤差，因此本研究利用重心自適應控制器以估測重心的偏差量，藉此修正機器人之實際重心位置。接著規劃機器人之行走模型，包含質心軌跡、支撐腳位置及擺動腳軌跡，使機器人能向前行走。本研究亦開發一彈性元件串聯於伺服馬達與負載之間，經由量測彈性元件之變形量，使伺服馬達達到串聯彈性致動器（SEA）的效果，使輸出力矩可以精準控制，藉此驗證重心估測自適應控制器之可行性並提昇機器人行走時的穩定性。

This thesis focuses on enhancing walking stability in bipedal robots. The traditional method needs accurate center of gravity (CoG); however, the measured CoG information is influenced by the posture of robot or measurement errors. We utilize an adaptive controller to estimate the actual CoG. The adaptive controller contains two parts: the adaption part and the PD control part. While the adaption part estimates the deviation between the measured and actual CoG to calculate the estimated CoG position, the PD control part uses the estimated CoG position and measured CoG velocity to stabilize the bipedal robot. Then we generate a walking pattern, including CoG trajectory, support leg position and swing leg trajectory, and utilize adaptive controller as stabilizer to control actual robot. In this thesis we design an elastic device which allows a conventional servo motor to be upgraded to serial elastic actuator (SEA). Therefore, we install SEA in ankles of robot to control torque accurately. Simulations and experiments verify the feasibility of enhancing stability in bipedal robots by the adaptive control algorithm and torque control.

[1] “Pepper,” Aldebaran Robotics, SoftBank Robotics Corp., [Online]. Available:https://www.ald.softbankrobotics.com/en/cool-robots/pepper.
[2] “Zenbo,” ASUSTeK Computer Inc., [Online]. Available: https://zenbo.asus.com/tw/.
[3] T. McGeer, “Passive dynamic walking,” The international journal of robotics research, vol. 2, no. 9, pp. 62-82, 1990.
[4] “ASIMO,” Honda Motor Co., Ltd., [Online]. Available: http://asimo.honda.com/.
[5] “NAO,” Aldebaran Robotics, SoftBank Robotics Corp., [Online]. Available: https://www.ald.softbankrobotics.com/en/cool-robots/nao.
[6] S. Kajita, H. Hirukawa, K. Harada and K. Yokoi, Introduction to humanoid robotics. Springer, 2014.
[7] C. F. Huang and T. J. Yeh, “Control of a Pedaled, Self-balanced Unicycle with Adaptation Capability,” 2014 11th International Conference on Informatics in Control, Automation and Robotics (ICINCO), Vienna, Austria, pp. 120-126, 2014.
[8] M. M. Williamson, Series elastic actuators. MASSACHUSETTS INST OF TECH CAMBRIDGE ARTIFICIAL INTELLIGENCE LAB, 1995.
[9] M. Vukobratovic, B. Borovac, D. Surla and D. Stokic, Biped locomotion: dynamics, stability, control and application. Springer Verlag, 1990.
[10] K. Hirai, M. Hirose, Y. Haikawa and T. Takenaka, “The development of Honda humanoid robot,” 1998 IEEE International Conference on Robotics and Automation, Leuven, vol. 2, pp. 1321-1326, 1998.
[11] P. A. Bhounsule, J. Cortell, A. Grewal, B. Hendriksen, J. G. D. Karssen, C. Paul and A. Ruina, “Low-bandwidth reflex-based control for lower power walking: 65 km on a single battery charge,” The International Journal of Robotics Research, vol. 33, pp. 1305-1321, 2014.
[12] E. R. Westervelt, J. W. Grizzle, C. Chevallereau, J. H. Choi and B. Morris, Feedback control of dynamic bipedal robot locomotion. CRC Press, 2007.
[13] J. W. Grizzle, C. Chevallereau, A. D. Ames and R. W. Sinnet, “3D bipedal robotic walking: models, feedback control, and open problems,” IFAC Proceedings Volumes, vol. 43, pp. 505-532, 2010.
[14] 黃浚鋒 (Huang, Chun-Feng). “腳踏動力自我平衡獨輪車之重心適應控制與打滑穩定器設計, Center of Gravity Adaptation and Anti-slip Control for a Pedaled Self-balanced Unicycle”. In: 清華大學動力機械工程學系學位論文(2016), pp. 1-122.
[15] X. Mu and Q. Wu, “Sagittal gait synthesis for a five-link biped robot,” Proceedings of the 2004 American Control Conference, Boston, MA, USA, vol. 5, pp. 4004-4009, 2004.
[16] “STM32F446RE,” STMicroelectronics, [Online]. Available: http://www.st.com/en/microcontrollers/stm32f446re.html
[17] “LSM9DS0,” SparkFun Electronics, [Online]. Available: https://www.sparkfun.com/products/retired/12636