论文标题

风险受限的线性季度调节器

Risk-Constrained Linear-Quadratic Regulators

论文作者

Tsiamis, Anastasios, Kalogerias, Dionysios S., Chamon, Luiz F. O., Ribeiro, Alejandro, Pappas, George J.

论文摘要

我们建议对标准线性二次调节器(LQR)问题进行新的风险约束。我们的框架是由于经典(风险中立的)LQR控制器虽然最佳预期,但在相对较少但统计学意义(风险)的事件下可能是无效的。为了有效地在平均事件和极端事件性能之间进行交易,我们引入了一种新的风险限制,该限制明确地将州罚款的预期预测性差异限制在用户规定的水平上。我们表明,在过程噪声(即有限的四阶矩)的相当最小的条件下,可以明确和封闭形式对最佳风险感知控制器进行评估。实际上,它是相对于状态的仿射,无论参数调整如何,它始终是内部稳定的。我们的新风险感知控制器:i)通过利用噪声的三阶力矩(偏斜)来将状态推开噪音表现出沉重的尾巴的方向; ii)在噪声协方差和州的罚款同时较大的情况下,在风险更大的方向上夸大了州的罚款。还通过指示性数值示例说明了所提出的风险感知LQR框架的特性。

We propose a new risk-constrained reformulation of the standard Linear Quadratic Regulator (LQR) problem. Our framework is motivated by the fact that the classical (risk-neutral) LQR controller, although optimal in expectation, might be ineffective under relatively infrequent, yet statistically significant (risky) events. To effectively trade between average and extreme event performance, we introduce a new risk constraint, which explicitly restricts the total expected predictive variance of the state penalty by a user-prescribed level. We show that, under rather minimal conditions on the process noise (i.e., finite fourth-order moments), the optimal risk-aware controller can be evaluated explicitly and in closed form. In fact, it is affine relative to the state, and is always internally stable regardless of parameter tuning. Our new risk-aware controller: i) pushes the state away from directions where the noise exhibits heavy tails, by exploiting the third-order moment (skewness) of the noise; ii) inflates the state penalty in riskier directions, where both the noise covariance and the state penalty are simultaneously large. The properties of the proposed risk-aware LQR framework are also illustrated via indicative numerical examples.

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