在機器人的研究領域中，致動器之控制性能為其首要元素，本文開發一串聯彈性致動器以達成各項驅動功能及良好的性能表現。其中串聯彈性致動器透過致動器與彈簧元件的結合，可經由量測並控制彈簧元件之變形量，達到相對於傳統剛性致動器更高準確度的力量與阻抗控制。同時彈簧元件亦具備緩衝效果，在致動器與人體或外界之力量交互作用中提供較高的安全性，因此更加適合應用於人機互動領域。然而目前有關串聯彈性致動器的研究大多使用直流有刷或無刷馬達作為驅動器，步進馬達之優勢並未受到足夠的關注。本文比較步進馬達與直流馬達之數據，發覺步進馬達有著遠高於直流馬達之扭矩重量比及扭矩轉子慣量比。因此選用步進馬達不僅可達到輕量化之功效，更可提高系統穩定性及響應速度於串聯彈性致動器之力量與阻抗控制中。藉由轉子角位置的回授，步進馬達亦可達成平順且具高準確度之動態力量響應。
本文選用步進馬達作為驅動器，設計一直線串聯彈性致動器之原型，並且建立步進馬達與導螺桿的數學模型。使用具備高迴圈速度及運算能力之嵌入式控制器NI CompactRIO®並設計驅動電路以進行馬達的回授控制，透過實驗鑑別與校正馬達參數、彈簧勁度及導螺桿摩擦係數等。接著建立力量控制器、阻抗控制器及干擾觀察器等控制架構，並完整分析系統之穩定性，以及透過響應規格最佳化的方式調整控制器增益值。同時使用商用軟體MATLAB®中的Simulink®建立模擬模型，以利於比較實驗與模擬結果，驗證本文建模之正確性。透過程式的撰寫將控制架構實現於實驗平台中，並進行順逆向力量與阻抗控制實驗達成本文期望之驅動功能以及高響應性能。最後藉由頻率響應分析並比對其他串聯彈性致動器之相關研究成果，驗證步進馬達高扭矩轉子慣量比所帶來的優勢。

A series elastic actuator (SEA) combines an actuator in series with an elastic spring. By controlling the deformation of the elastic spring, an SEA provides more accurate force and impedance control than conventional rigid actuators. SEAs are ideal for robots and machines that need to interact safely with human or the environment. The majority of existing SEAs uses brushless or brushed DC motors as the actuators. The advantages of using stepper motors as the actuators of SEAs have not received enough attention. Stepper motors have much higher torque-to-weight ratio and torque-to-rotor-inertia ratio than other DC motors. Hence they can provide better stability and high-speed accuracy of force control while maintaining lightweight. When rotor position feedback is used, stepper motors can achieve smooth and ultra-accurate dynamic force response. This thesis develops the dynamic model of a linear SEA and presents its prototype. Forward and inverse force/impedance tracking control responses will be provided to show the advantages of the SEA. It is expected that the method and result presented here can offer a better actuator selection of SEAs when higher torque-to-weight ratio and torque-to-rotor-inertia ratio are both required.

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