For humans, fast, efficient walking over flat ground represents the vast majority of locomotion that an individual experiences on a daily basis, and for an effective, real-world humanoid robot the same will likely be the case. In this work, we propose a locomotion controller for efficient walking over near-flat ground using a relatively simple, model-based controller that utilizes a novel combination of several interesting design features including an ALIP-based step adjustment strategy, stance leg length control as an alternative to center of mass height control, and rolling contact for heel-to-toe motion of the stance foot. We then present the results of this controller on our robot Nadia, both in simulation and on hardware. These results include validation of this controller's ability to perform fast, reliable forward walking at 0.75 m/s along with backwards walking, side-stepping, turning in place, and push recovery. We also present an efficiency comparison between the proposed control strategy and our baseline walking controller over three steady-state walking speeds. Lastly, we demonstrate some of the benefits of utilizing rolling contact in the stance foot, specifically the reduction of necessary positive and negative work throughout the stride.

翻译：对于人类而言，在平坦地面上快速、高效地行走是日常生活中最常见的运动方式，而对于实用化的仿人机器人而言，这一需求同样至关重要。本研究提出了一种适用于近平坦地面的高效行走控制器，该控制器采用相对简单的基于模型的架构，创新性地融合了多种设计要素：基于ALIP的步幅调整策略、以支撑腿长度控制替代质心高度控制的方案，以及支撑脚实现足跟-足尖运动的滚动接触机制。我们随后在机器人Nadia上（包括仿真与实物实验）展示了该控制器的效果，验证了其在0.75米/秒速度下的正向行走能力，以及倒退行走、侧向移动、原地转向和抗扰动恢复等性能。此外，我们通过三种稳态行走速度下的对比实验，评估了所提控制策略与基准行走控制器的能效差异。最后，我们证明了支撑脚采用滚动接触的若干优势，特别是能有效减少步态周期中所需的正负功。