Controlling an underactuated robot is always an important research and engineering issue, especially when the robot is suffering from multiple sources of uncertainties, such as unmodeled dynamics, external disturbance, and parameter uncertainties. To cope with these uncertainties in such uncertain nonlinear systems which is not fully-actuated, this paper proposes a control method that can actively estimate these uncertainties via the extended state observer (ESO), under the scheme of output-feedback control, the lumped uncertainties can be online estimated and actively compensated. Every joint of the underactuated robotic system can robustly reach the pre-given state in finite-time even though there are only fewer joints than the actual number of joints that can be controlled directly. The experimental results demonstrate the control process and validate that the proposed method is feasible for the studied underactuated robotic system.

中文翻译：

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基于扩展状态观测器的鲁棒有限控制器设计：针对多不确定源的欠驱动机器人系统

控制欠驱动机器人一直是一个重要的研究和工程问题，尤其是当机器人受到多种不确定性来源的影响时，例如未建模的动力学、外部干扰和参数不确定性。针对这种非全驱动的不确定非线性系统中的这些不确定性，本文提出了一种通过扩展状态观测器（ESO）主动估计这些不确定性的控制方法，在输出反馈控制方案下，集中不确定性可在线估价，主动补偿。欠驱动机器人系统的每个关节都可以在有限时间内稳健地达到预先给定的状态，即使关节数量仅少于可直接控制的实际关节数量。