本論文的研究目的是研製以無螺牙滾珠螺桿為主要減速系統的微型串列彈性致動器，搭配微型直流有刷馬達及相關動力傳動系統的最小化來降低致動器的體積。致動器設定為適用在機器人的關節驅動系統上，此致動器能在縮小體積之餘依然有足夠的運作效能輸出。
無螺牙滾珠螺桿具有若干優點，包括成本低、製作門檻低、可依據需求彈性地設定減速比、負載過大時螺桿零件不易損壞、容易取得相關零件等。為了模擬關節的柔軟性，動力傳動系統末端串列安裝彈性元件，以彈簧吸收瞬間的衝擊力並達到能量儲存後加以釋放的效果。部分零件採用UV光固化3D列印製作，3D列印技術能在維持一定程度的零件品質之餘達到迅速取得成品、降低整體開發時間、降低成本等優勢。
根據實驗結果，本論文研製之微型串列彈性致動器，彈性元件能儲存約58mNm扭矩的能量，透過釋放能量提高輸出轉速，平均角速度最高能提升為1.8倍，最大角速度最高能提升為2倍。

This thesis serves to research and develop threadless ballscrews (TLBS) as a primary speed reduction system for a micro-elastic actuator. The TLBS is paired with a DC motor and a minimized power transmission system to reduce the physical size of the actuator. The actuator is designed specifically for a robot’s joint system, providing sufficient power while retaining its size advantage.
TLBS has several benefits, such as low cost, easy to produce, self-locking, adjustable speed reduction, able to withhold heavy weights without breaking, easy to access its components, etc. To simulate a joint’s flexibility, an elastic component is installed at the end of the power transmission system, using a spring to absorb the instantaneous force and storing it for later release. Parts of the TLBS are made by a 3D printer, which has the advantage of fast accessibility, lower production time, lower overall cost, etc.
According to the experimental results, the elastic element is able to store 58 mNm torque worth of energy, and through releasing this energy to increase its rpm. The average rpm can be increased by 1.8 times, while the highest rpm can be increased by 2 times.

[1] G. Pratt and M.Williamson, “Series Elastic Actuators,” in Proc. IEEE/RSJ Int. Conf. Intell. Robot. Syst. Human Robot Interact. Cooper. Robot., vol. 1, pp. 399–406, Aug.1995.
[2] S. Arumugom, S. Muthuraman, and V. Ponselvan, “Modeling and Application of Series Elastic Actuators for Force Control Multi Legged Robots,” J.Comput., vol. 1, no. 1, pp. 26–33, Dec. 2009.
[3] D. Paluska and H. Herr, “Series Elasticity and Actuator Power Output,” in Proc. IEEE Int. Conf. Robot. Autom., pp. 1830–1833, May 2006.
[4] N. Paine, S. Oh, L. Sentis, “Design and Control Considerations for High-Performance Series Elastic Actuators,” IEEE/ASME Transactions on Mechatronics, vol. 19, no. 3, pp. 1080-1091, Jun. 2014.
[5] K. Kong, J. Bae, and M. Tomizuka, “Control of Rotary Series Elastic Actuator for Ideal Force-Mode Actuation in Human-robot Interaction Applications,” IEEE/ASME Trans. Mechatronics, vol. 14, no. 1, pp. 105–118, Feb. 2009.
[6] N.G.Tsagarakis, Matteo Laffranchi, Bram Vanderborght, Darwin G.Caldwell, “A Compact Soft Actuator Unit for Small Scale Human Friendly Robots,” Proc. of IEEE ICRA 2009, pp. 4356-4362.
[7] F. Sergi, D. Accoto, G. Carpino, N. L. Tagliamonte, E. Guglielmelli, “Design and Characterization of a Compact Rotary Series Elastic Actuator for Knee Assistance During Overground Walking,” Biomedical Robotics and Biomechatronics (BioRob), 2012 4th IEEE RAS & EMBS International Conference on, pp. 1931-1936, Rome, 24-27 June 2012.
[8] N.G.Tsagarakis, Z. Li, J. Saglia and D.G. Caldwell, "The Design of the Lower Body of the Compliant Humanoid Robot“cCub”," Robotics and Automation (ICRA), 2011 IEEE International Conference on, pp. 2035 - 2040, 9-13 May 2011.
[9] C. Semini, N. G. Tsagarakis, E. Guglielmino, D. G. Caldwell, “Design and Experimental Evaluation of the Hydraulically Actuated Prototype Leg of the HyQ Robot,” IEEE/RSJ Int. Conf. on Intelligent Robots and Systems (IROS), 2010.
[10] B. Ugurlu, I. Havoutis, C. Semini, D. G. Caldwell, “Dynamic Trot-Walking with the Hydraulic Quadruped Robot – HyQ: Analytical Trajectory Generation and Active Compliance Control,” IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), 2013.
[11] Sprowitz, Alexander; Tuleu, Alexandre; Vespignani, Massimo; Ajallooeian, Mostafa; Badri, Emilie; Ijspeert, Auke, "Towards Dynamic Trot Gait Locomotion-Design, Control and Experiments with Cheetah-cub, a Compliant Quadruped Robot," The International Journal of Robotics Research 0278364913482017, first published June 17, 2013
[12] M. Hutter, C. D. Remy, M. A. Hoepflinger, and R. Siegwart, “Efficient and Versatile Locomotion with Highly Compliant Legs”, IEEE/ASME Transactions on Mechatronics, vol. 18, no. 2, pp. 449-458, April 2013.
[13] M. Hutter, C. Gehring, M. Bloesch, M. Hoepflinger, C. D. Remy, R. Siegwart, “StarlETH: A Compliant Quadrupedal Robot for Fast, Efficient, and Versatile Locomotion”, Proc. of the International Conference on Climbing and Walking Robots (CLAWAR), 2012.
[14] M. Hutter, M. Hoepflinger, C. Gehring, M. Bloesch, C. D. Remy, R. Siegwart, “Hybrid Operational Space Control for Compliant Legged Systems”, Proc. of the 8th Robotics: Science and Systems Conference (RSS), 2012.
[15] M. E. Swanberg, Claremont, Calif, “Linear Actuator,” U.S. Patent No.3777578, 1973.
[16] J. Rasmussen, O. Hauberg, “Friction Drive Mechanism for Converting a Rotational Movement Into an Axial Movement, Or Vice Versa,” U.S. Patent No.4246802, 1981.
[17] G. J. Musial, W. Boxford, Mass, “Traverse Mechanism and Method,” U.S. Patent No.4236415, 1980.
[18] R. A. E. Wood, E. Godson, H. E. Flory, “Device for Converting Rotary Movement Into Linear Movement,” U.S. Patent No.4718291, 1988.
[19] M. Marcovici, “Precise Linear Actuator,” U.S. Patent No.4411166, 1983.
[20] Microchip Technology Inc., “PIC16F/LF1825/1829 Data Sheet,” http://ww1.microchip.com/downloads/en/DeviceDoc/41440A.pdf (2014/7)
[21] Maxon Motor Ag, Inc., “ESCON 36/2 DC Hardware Reference,” http://www.maxonmotorusa.com/medias/sys_master/8810873552926/403112-ESCON-36-2-DC-Hardware-Reference-En.pdf (2014/7)
[22] Maxon Motor Ag, Inc., “DCX 10 L bruched DC motor Ø10mm,” http://www.maxonmotorusa.com/medias/sys_master/8813571014686/14-59-EN.pdf (2014/7)
[23] Bourns Inc., “3382-12mm Rotary Position Sensor,” http://www.bourns.com/data/global/pdfs/3382.pdf (2014/7)