The Cell Transmission Model (CTM) has been widely used to design variable speed limit (VSL) controllers. Since the CTM is an idealization of the actual traffic flow, the issue of robustness of VSL with respect to uncertainties such as disturbances due to modeling and measurement errors is an important problem. In this paper, we modify the CTM to include a constant disturbance term that is unknown and could change over time. The stability properties of the modified open-loop CTM are analyzed and used to motivate the design of a robust VSL controller. The VSL controller is designed to reject external disturbances, which are constant over large intervals of time, while guaranteeing that the density converges to the desired equilibrium state corresponding to high flow and speed. Microscopic simulations based on the commercial software VISSIM are used to demonstrate the effectiveness of the proposed robust VSL controller and associated benefits for traffic scenarios along a large segment of I-710 in Southern California.

信元传输模型（CTM）已被广泛用于设计变速限制（VSL）控制器。由于CTM是实际流量的理想选择，因此VSL关于不确定性（例如由于建模和测量误差引起的干扰）的鲁棒性问题是一个重要问题。在本文中，我们将CTM修改为包括一个未知的常数扰动项，该扰动项可能随时间变化。分析了改进的开环CTM的稳定性，并将其用于激励强大的VSL控制器的设计。VSL控制器被设计为抑制外部干扰，该干扰在较大的时间间隔内保持恒定，同时确保密度收敛到与高流量和高速度相对应的所需平衡状态。