ITS Berkeley

Well-Posedness of Networked Scalar Semilinear Balance Laws Subject to Nonlinear Boundary Control Operators

Tang, Shu-Xia
Keimer, Alexander
Bayen, Alexandre M.
2019

Networked scalar semilinear balance laws are used as simplified macroscopic vehicular traffic models. The related initial boundary value problem is investigated, on a finite interval. The upstream boundary datum is determined by a nonlinear feedback control operator, representing the fact that traffic routing might be influenced in real time by the traffic information on the entire network. The main contribution of the present work lies in the appropriate design of nonlinear boundary control operators which meanwhile guarantee the well-posedness of the resultant systems. In detail, two...

A Study on Minimum Time Regulation of a Bounded Congested Road with Upstream Flow Control

Tang, Shu-Xia
Keimer, Alexander
Goatin, Paola
Bayen, Alexandre M.
2019

This article is motivated by the practical problem of controlling traffic flow by imposing restrictive boundary conditions. For a one-dimensional congested road segment, we study the minimum time control problem of how to control the upstream vehicular flow appropriately to regulate the downstream traffic into a desired (constant) free flow state in minimum time. We consider the Initial-Boundary Value Problem (IBVP) for a scalar nonlinear conservation law, associated to the Lighthill-Whitham-Richards (LWR) Partial Differential Equation (PDE), where the left boundary condition, also treated...

Inter-Level Cooperation in Hierarchical Reinforcement Learning

Rahman Kreidieh, Abdul
Berseth, Glen
Trabucco, Brandon
Parajuli, Samyak
Levine, Sergey
Bayen, Alexander M.
2019

Hierarchies of temporally decoupled policies present a promising approach for enabling structured exploration in complex long-term planning problems. To fully achieve this approach an end-to-end training paradigm is needed. However, training these multi-level policies has had limited success due to challenges arising from interactions between the goal-assigning and goal-achieving levels within a hierarchy. In this article, we consider the policy optimization process as a multi-agent process. This allows us to draw on connections between communication and cooperation in multi-agent RL, and...

Daily Data Assimilation of a Hydrologic Model Using the Ensemble Kalman Filter

Malek, Sami A.
Bayen, Alexandre M.
Glaser, Steven D.
2019

Accurate runoff forecasting is crucial for reservoir operators as it allows optimized water management, flood control and hydropower generation. Land surface models in mountainous regions depend on climatic inputs such as precipitation, temperature and solar radiation to model the water and energy dynamics and produce runoff as output. With the rapid development of cheap electronics applied in various systems, such as Wireless Sensor Networks (WSNs), satellite and airborne technologies, the prospect of practically measuring spatial Snow Water Equivalent in a dense temporal scale is...

Emergent Complexity and Zero-shot Transfer via Unsupervised Environment Design

Dennis, Michael
Jaques, Natasha
Vinitsky, Eugene
Bayen, Alexandre
Russell, Stuart
Critch, Andrew
Levine, Sergey
2020

A wide range of reinforcement learning (RL) problems --- including robustness, transfer learning, unsupervised RL, and emergent complexity --- require specifying a distribution of tasks or environments in which a policy will be trained. However, creating a useful distribution of environments is error prone, and takes a significant amount of developer time and effort. We propose Unsupervised Environment Design (UED) as an alternative paradigm, where developers provide environments with unknown parameters, and these parameters are used to automatically produce a distribution over valid,...

A Macroscopic Traffic Flow Model with Finite Buffers on Networks: Well-Posedness by Means of Hamilton-Jacobi Equations

Laurent-Brouty, Nicolas
Keimer, Alexander
Goatin, Paola
Bayen, Alexandre
2020

We introduce a model dealing with conservation laws on networks and coupled boundary conditions at the junctions. In particular, we introduce buffers of fixed arbitrary size and time dependent split ratios at the junctions , which represent how traffic is routed through the network, while guaranteeing spill-back phenomena at nodes. Having defined the dynamics at the level of conservation laws, we lift it up to the Hamilton-Jacobi (H-J) formulation and write boundary datum of incoming and outgoing junctions as functions of the queue sizes and vice-versa. The Hamilton-Jacobi formulation...

Long-Term Digital Device-Enabled Monitoring of Functional Status: Implications for Management of Persons with Alzheimer's Disease

Manley, Natalie A.
Bayen, Eleonore
Braley, Tamara L.
Merrilees, Jennifer
Clark, Amy M.
Zylstra, Bradley
Schaffer, Michael
Bayen, Alexandre
Possin, Katherine L.
2020

Introduction Informal caregiving is an essential element of health-care delivery. Little data describes how caregivers structure care recipients’ lives and impact their functional status. Methods We performed observational studies of community dwelling persons with dementia (PWD) to measure functional status by simultaneous assessment of physical activity (PA) and lifespace (LS). We present data from two caregiver/care-recipient dyads representing higher and average degrees of caregiver involvement. Results We acquired >42,800 (subject 1); >41,300 (subject 2) PA data points and >...

Learning Optimal Traffic Routing Behaviors Using Markovian Framework in Microscopic Simulation

Cabannes, T.
Li, J.
Wu, F.
Dong, H.
Bayen, A.M.
2020

This article applies the existing Markovian traffic assignment framework to novel traffic control strategies. In the Markovian traffic assignment framework, transition matrices are used to derive the traffic flow allocation. In contrast to the static traffic assignment, the framework only requires flow split ratio at every intersection, bypassing the need of computing path flow allocation. Consequently, compared to static traffic assignment, drivers’ routing behaviors can be modeled with fewer variables. As a result, it could be used to improve the efficiency of traffic management,...

Block Simplex Signal Recovery: Methods, Trade-Offs, and an Application to Routing

Wu, Cathy
Pozdnukhov, Alexey
Bayen, Alexandre M.
2020

This paper presents the problem of block simplex constrained signal recovery, which has been demonstrated to be a suitable formulation for estimation problems in networks such as route flow estimation in traffic. There are several natural approaches to this problem: compressed sensing, Bayesian inference, and convex optimization. This paper presents new methods within each framework and assesses their respective abilities to reconstruct signals, with the particular emphasis on sparse recovery, ability to incorporate prior information, and scalability. We then apply these methods to route...

Routing on Traffic Networks Incorporating Past Memory up to Real-Time Information on the Network State

Keimer, Alexander
Bayen, Alexandre
2020

In this review, we discuss routing algorithms for the dynamic traffic assignment (DTA) problem that assigns traffic flow in a given road network as realistically as possible. We present a new class of so-called routing operators that route traffic flow at intersections based on either real-time information about the status of the network or historical data. These routing operators thus cover the distribution of traffic flow at all possible intersections. To model traffic flow on the links, we use a well-known macroscopic ordinary delay differential equation. We prove the existence and...