In this paper, we present a method to robustify asymptotically stable nonlinear systems by adding an integral action that rejects unknown additive disturbances. The proposed approach uses a port-Hamiltonian (pH) representation of the open-loop dynamics, which, relying on the asymptotic stability property, is guaranteed to exist. The integral action controller preserves the pH structure, and, by adding a suitable cross term between the plant and the controller states to the closed-loop energy function, it avoids the unnatural coordinate transformation used in the past. The controller is shown to be robust against some common types of modeling uncertainty, including unknown friction dynamics in mechanical systems.

中文翻译：

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一类非线性系统的匹配抗扰

在本文中，我们提出了一种通过添加拒绝未知加性扰动的积分作用来增强渐近稳定非线性系统的方法。所提出的方法使用开环动力学的 port-Hamiltonian (pH) 表示，它依赖于渐近稳定性属性，保证存在。积分作用控制器保留了 pH 结构，并且通过在闭环能量函数中添加一个合适的植物和控制器状态之间的交叉项，避免了过去使用的不自然的坐标变换。控制器显示出对一些常见类型的建模不确定性的鲁棒性，包括机械系统中的未知摩擦动力学。