Linjun Zhang

DESIGNING NETWORK MOTIFS IN CONNECTED VEHICLE SYSTEMS: DELAY EFFECTS AND STABILITY

Arising technologies in vehicle-to-vehicle (V2V) communication allow vehicles to obtain information about the motion of distant vehicles. Such information can be presented to the driver or incorporated in advanced autonomous cruise control (ACC) systems. In this paper, we investigate the effects of multi-vehicle communication on the dynamics of connected vehicle platoons and propose a motif-based approach that allows systematical analysis and design of such systems. We investigate the dynamics of simple motifs in the presence of communication delays, and show that long-distance communication can stabilize the uniform flow when the flow cannot be stabilized by nearest neighbor interactions. The results can be used for designing driver assist systems and communication-based cruise control systems.Copyright

Hierarchical Design of Connected Cruise Control in the Presence of Information Delays and Uncertain Vehicle Dynamics

In this paper, we investigate the design of connected cruise control that exploits wireless vehicle-to-vehicle communication to enhance vehicle mobility and safety. A hierarchical framework is used to reduce the complexity for design and analysis. A high-level controller incorporates the motion data received from multiple vehicles ahead and also considers information delays, in order to generate the desired longitudinal dynamics. At the lower level, we consider a physics-based vehicle model and design an adaptive sliding-mode controller that regulates the engine torque, so that the vehicle can track the desired dynamics in the presence of uncertainties and external perturbations. Numerical simulations are used to validate the analytical results and demonstrate the robustness of the controller.

Stability analysis of nonlinear connected vehicle systems

In this paper, we investigate the nonlinear dynamics of connected vehicle systems. Vehicle-to-vehicle (V2V) communication is exploited when controlling the longitudinal motion of a few vehicles in the traffic flow. In order to achieve the desired systemlevel behavior, the plant stability and the head-to-tail string stability are characterized at the nonlinear level using Lyapunov functions. A motif-based approach is utilized that allows modular design for large-scale vehicle networks. Stability analysis of motifs are summarized using stability diagrams, which are validated by numerical simulations.

Hierarchical Design for Connected Cruise Control

In this paper, we propose a hierarchical framework to reduce the design complexity of connected cruise control (CCC), which is used to regulate the longitudinal motion of a vehicle by utilizing wireless vehicle-to-vehicle (V2V) communication. A high-level controller is designed to generate desired motion of the CCC vehicle based on the motion of multiple vehicles ahead. A low-level controller is used to regulate the engine torque and select the appropriate gear to enable the vehicle to track the desired motion. To cope with external disturbances and uncertain physical parameters, we use an adaptive control strategy for the low-level controller. In a case study, we design a specific CCC algorithm by using the presented hierarchical framework. Numerical simulations are used to validate the analytical results and test the system performance.Copyright

Beyond-Line-of-Sight Identification by Using Vehicle-to-Vehicle Communication

In this paper, we investigate the identification of the configuration and the dynamics of connected vehicle systems, where wireless vehicle-to-vehicle communication is used to access the motion data of vehicles that are beyond the line of sight. In particular, we first construct a causality detector to determine whether the information received from distant vehicles is relevant to the motion of the receiving vehicle. Then, we design a link-length estimator to identify the number of vehicles between the broadcasting vehicle and the receiving vehicle, which is required for appropriately incorporating the received data into the vehicle control system. Finally, a dynamics identifier is proposed to approximate the nonlinear time-delayed dynamics of vehicle chains, which is needed for the controller design to achieve desired system-level performance. The presented analytical results are validated through numerical simulations using synthetic data and on-road experiments.

Black-box modeling of connected vehicle networks

In this paper, we propose a black-box modeling framework for connected vehicle networks comprised of conventional vehicles and vehicles equipped with wireless vehicle-to-vehicle (V2V) communication. First, we identify the link length that is the number of vehicles between the broadcasting and the host vehicle. Based on the estimated link length, a linear model is used to approximate the dynamics of the vehicle network. The proposed framework does not require priori information about the dynamics of the vehicle network, and hence can be implemented in real traffic. Numerical simulations are used to demonstrate the effectiveness of the estimators in capturing the link length and predicting the time evolution of the vehicle network. The estimated model can be used when designing connected cruise control (CCC) algorithms.