Abstract Legged-wheeled robots combine the advantages of efficient wheeled mobility with the capability of adapting to real-world terrains through the legged locomotion. Thanks to their hybrid mobility skill, they can excel in many application scenarios where other mobile platforms are not suitable for. However, the improved versatility of their mobility increases the number of constraints in their motion control, where both the properties of legged and wheeled functionalities need to be considered. Relevant schemes for legged-wheeled motion control so far have attempted to address the problem by exploiting separate motion control of the wheeled and legged functionalities. The contribution of this paper is the introduction of derivation of the legged-wheeled motion kinematics without constraining the camber angles of the wheels. To this end, the wheel geometry is approximated by torus that more precisely represents a real wheel geometry than a standard sphere/cylinder. On the basis of the derived legged-wheeled motion kinematics, a first-order inverse kinematics (IK) scheme that resolves the legged-wheeled robot whole-body motion respecting the wheel rolling constraint is described. Furthermore, a higher-level method to resolve wheel steering to comply with a non-holonomic constraint is designed. A damping scheme is proposed to handle a structural singularity when a system non-holonomy deteriorates. Finally, the work adopts a floating base model that allows to easily incorporate the legged motion into the proposed scheme. The developed control scheme is tested in experiments on a legged-wheeled centaur-like robot — CENTAURO.

中文翻译：

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混合动力 CENTAURO 机器人的轮式运动学和控制

摘要 腿轮式机器人结合了高效轮式移动的优点和通过腿式运动适应现实世界地形的能力。由于他们的混合移动能力，他们可以在许多其他移动平台不适合的应用场景中表现出色。然而，其机动性的改进多功能性增加了其运动控制中的约束数量，其中需要考虑腿式和轮式功能的特性。迄今为止，腿式轮式运动控制的相关方案已尝试通过利用轮式和腿式功能的单独运动控制来解决该问题。本文的贡献是在不限制车轮外倾角的情况下引入了腿式轮式运动学的推导。为此，车轮几何形状由环面近似，它比标准球体/圆柱体更准确地表示真实的车轮几何形状。在推导的腿轮运动运动学的基础上，描述了解决腿轮机器人全身运动的一阶逆运动学（IK）方案，该方案考虑车轮滚动约束。此外，设计了一种更高级的方法来解决车轮转向以符合非完整约束。当系统非完整性恶化时，提出了一种阻尼方案来处理结构奇异性。最后，该作品采用浮动底座模型，可以轻松地将腿部运动纳入所提出的方案中。开发的控制方案在一个有腿的半人马机器人 - CENTAURO 上进行了实验测试。