论文标题

Deep Koopman操作员,具有非线性系统的控制

Deep Koopman Operator with Control for Nonlinear Systems

论文作者

Shi, Haojie, Meng, Max Q. -H.

论文摘要

最近,Koopman运营商已成为一个有前途的数据驱动工具,可促进未知非线性系统的实时控制。它将非线性系统映射到嵌入空间中的等效线性系统中,准备实时线性控制方法。但是,设计合适的Koopman嵌入功能仍然是一项具有挑战性的任务。此外,大多数基于Koopman的算法仅考虑具有线性控制输入的非线性系统,从而在系统完全非线性(具有控制输入的系统完全非线性)时会导致糟糕的预测和控制性能。在这项工作中,我们提出了一个端到端的深度学习框架,以学习Koopman嵌入功能和Koopman操作员,以减轻此类困难。我们首先使用神经网络对嵌入功能和Koopman操作员进行参数化,并使用K-Steps损耗函数端到端训练它们。然后,增强辅助控制网络以编码非线性状态依赖性控制项,以模拟控制输入中的非线性。该编码术语被认为是新的控制变量,而是确保嵌入式系统中建模系统的线性性。我们接下来在线性嵌入空间上部署线性二次调节器(LQR),以得出最佳控制策略并从控制NET中解释实际控制输入。实验结果表明,我们的方法表现优于其他现有方法,通过数量级顺序降低预测误差,并在几种非线性动态系统(如阻尼摆,Cartpole和七个DOF机器人手动机器)中实现出色的控制性能。

Recently Koopman operator has become a promising data-driven tool to facilitate real-time control for unknown nonlinear systems. It maps nonlinear systems into equivalent linear systems in embedding space, ready for real-time linear control methods. However, designing an appropriate Koopman embedding function remains a challenging task. Furthermore, most Koopman-based algorithms only consider nonlinear systems with linear control input, resulting in lousy prediction and control performance when the system is fully nonlinear with the control input. In this work, we propose an end-to-end deep learning framework to learn the Koopman embedding function and Koopman Operator together to alleviate such difficulties. We first parameterize the embedding function and Koopman Operator with the neural network and train them end-to-end with the K-steps loss function. Then, an auxiliary control network is augmented to encode the nonlinear state-dependent control term to model the nonlinearity in the control input. This encoded term is considered the new control variable instead to ensure linearity of the modeled system in the embedding system.We next deploy Linear Quadratic Regulator (LQR) on the linear embedding space to derive the optimal control policy and decode the actual control input from the control net. Experimental results demonstrate that our approach outperforms other existing methods, reducing the prediction error by order of magnitude and achieving superior control performance in several nonlinear dynamic systems like damping pendulum, CartPole, and the seven DOF robotic manipulator.

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