足式機器人動態跑步步態之基礎模型探索

Abstract

本研究致力於基礎模型之探索與開發，首先在實驗室先前所開發之rolling SLIP (R-SLIP)模型基礎上加入位置控制之考量，建構clock torqued rolling SLIP (CTR-SLIP)模型，使模型得以作為機器人暫態與穩態行為之模版。本文探討與分析模型之三維收斂區間，收斂範圍內不同的落地條件使模型和機器人可以做穩定點間之轉換。實驗結果證實，機器人能雙向成功地切換兩跑動速度下之動態，此結果之特點在於此作法純粹以模型為基礎，不需要額外之調整、優化與學習。 再者，本文以R-SLIP模型所衍生之腳部軌跡為基礎，對軌跡週期縮放所產生的動態進行探究，討論常用於行走步態上之腳部軌跡線性週期縮放方式對於機器人之影響。藉由CTR-SLIP模型，可以模擬並分析系統之動態。實驗部分顯示，在一定程度的週期縮放範圍內，機器人可以呈現不同於原本軌跡穩定點動態之穩定步態。 第三，本研究以R-SLIP模型雙週期被動動態為基礎，建構機器人跑動步態雙週期動態。模擬上，使用return map分析雙週期穩定點之分布，探討兩步相同與相異落地角度之動態。實驗部分，將兩組雙週期腳部軌跡實現於機器人上，結果顯示機器人確實能呈現雙週期動態步態。 最後，本文探討簡化模型之性質對於動態的影響，先以不同地面接觸條件與自由度耦合情形之四個簡化模型進行討論，而後建構Generalized-SLIP (G-SLIP)廣義模型涵蓋此四模型，進一步進行模型性質變動之探討。此外，利用G-SLIP廣義模型，可以在定義的代價函數下對模型參數進行優化，得到特定條件下之優化模型，其優化結果可對於此條件下機器人之腳部設計予以建議。

This research is dedicate to the exploration and development of reduce-order models. First, this thesis reports on the development of the clock-torqued rolling spring loaded inverted pendulum (CTR-SLIP) model. The new model adds clock-based torque control on the leg orientation of the previously-developed R-SLIP model so it can serve as the dynamic motion template to guide both transient and steady-state running of the robot as the anchor. The 3-dimenaional BOA of the model is investigated and analyzed, and the inclusion of the touchdown speed in BOA of the model enables the model/robot to perform speed transition from one fixed point profile to another. The experiment results confirm that the robot can successfully transit between two running speeds bi-directionally. The achievement of variable-speed running on the model and robot by the proposed method has a unique merit that it is purely model-based, no needs for further tuning, optimizing, or learning process. Secondly, the dynamic motion generation of a robot with leg trajectories derived from the fixed-point trajectories of the R-SLIP model is studied. This research investigates the effect of linear period scaling, which is widely used in walking gait, on the dynamics of the robot. On the base of CTR-SLIP model, the dynamics of the system are simulated and analyzed. The experimental results show that a robot using a clock with period variation in a certain range of the original fixed point can perform stable dynamic motions, yet with a profile that differs from the original profile. Third, this thesis explored the generation of period two dynamic running motion in a robot, based on the passive dynamic period two motion of R-SLIP model. The distribution of the period two fixed points of the model was analyzed using a return map. Models with the same or different landing angles per motion cycle were studied, and two sets of period two motion trajectories were implemented in a robot for experimental evaluation. Based on the experiments, the robot was capable of performing dynamic period two motion. Finally, this research explores the effects of the property of reduced-order models on the dynamics. Four basic models with different contact and couple property are discussed and a general model, Generalized-SLIP (G-SLIP) model is constructed. This general model includes the special cases of four models and helps explore the variation of the model properties. In addition, based on G-SLIP model, the reduce-order model can be optimized with certain defined cost function. The optimal result suggests the better leg configuration for the demand.