Yunfei Hou

Integrated Traffic-Driving-Networking Simulator for the Design of Connected Vehicle Applications: Eco-Signal Case Study

This article first develops an integrated traffic-driving-networking simulator (ITDNS) intended for the design and evaluation of cyber transportation systems (CTS) and connected vehicle (CV) applications. The ITDNS allows a human driver to control a subject vehicle, in a virtual environment, that is capable of communicating with other vehicles and the infrastructure with CTS messages. The challenges associated with the integration of the three simulators, and how those challenges were overcome, are discussed. As an application example, an eco-signal system, which recommends the approach speed for vehicles approaching the intersection so as to minimize fuel consumption and emissions, was implemented in the ITDNS. Test drivers were then asked to virtually drive through a signalized corridor twice, one time with the eco-signal system in place and another without the system. Thanks to the human-in-the-loop component of ITDNS, the research was able to evaluate the likely benefits of the eco-signal system, while accounting for the response of human drivers to the recommended speed profiles. Moreover, the study compared the energy consumption and emission production rates of human-controlled vehicles’ approach trajectories to the rates associated with “idealistic” trajectories that may be attainable via vehicle automation. With respect to ITDNS, the study demonstrates the unique advantages of the simulator and the broad range of applications it can address. Regarding the eco-signal application example, preliminary results demonstrate the potential of the concept to result in tangible reductions of around 9% for energy consumption, 18% for carbon monoxide, and 25% for nitrogen oxides emissions. Moreover, the application eliminated hard accelerations and decelerations maneuvers, and thus may have an additional positive safety impact.

Towards efficient vacant taxis Cruising Guidance

Different from the conventional operation mode in existing taxi dispatch systems, in this paper, we envision a new cyber-technology enabled taxi dispatch system which can efficiently provide vacant taxis with cruising route suggestions, not to respond to any specific pick-up request but instead, hoping to find prospective customers (such system is also complementary to the conventional operation mode). We address the Taxi Cruising Guidance (TCG) problem with the objective being to minimize the Global Vacant Rate (GVR), which is defined as the ratio of traveling miles with no passenger onboard, to the total traveling miles in a given time period. We propose a number of heuristic solutions and conduct comprehensive performance evaluations based on large-scale simulations. A case study is also presented by utilizing real traces collected from taxis in the city of Shanghai. As part of our research, we leverage a well-known microscopic traffic simulator (called TRANSIMS) to demonstrate that the application of TCG is also beneficial to traffic management.

On-road ads delivery scheduling and bandwidth allocation in vehicular CPS

We consider a promising application in Vehicular Cyber-Physical Systems (VCPS) called On-road Ad Delivery (OAD), where targeted advertisements are delivered via roadside APs to attract commuters to nearby shops. Different from most existing works on VANETs which only focused on a single technical area, this work on OAD involves technical elements from human factors, cyber systems and transportation systems since a commuters shopping decision depends on e.g. the attractiveness of the ads, the induced detour, and traffic conditions on different routes. In this paper, we address a new optimization problem in OAD whose goal is to schedule ad messages and allocate a limited amount of AP bandwidth so as to maximize the system-wide performance in terms of total realized utilities (TRU) of the delivered ads. A number of efficient heuristics are proposed to deal with ad message scheduling and AP bandwidth allocation. Besides largescale simulations, we also present a case study in a more realistic scenario utilizing real traces collected from taxis in the city of Shanghai. In addition, we use a commercial traffic simulator (PARAMICS) to show that our proposed solutions are also useful for traffic management in terms of balancing vehicular traffic and alleviating congestion.

Simulation-Based Testing and Evaluation Tools for Transportation Cyber–Physical Systems

Transportation cyber-physical systems (TCPSs) require simulation-based testing and evaluation due to the prohibitive cost of building realistic test beds. Given the transdisciplinary nature of TCPSs, various simulation models and frameworks have been proposed in civil engineering, computer science, and related fields. Traditionally, researchers in different areas have developed their own set of simulation tools, which provide limited capability for TCPS research. In recent years, we have witnessed a growing interest of combining two or more features of traditional simulators to capture the unique characteristics of TCPSs. In this paper, we describe several mainstream simulation models used in transportation, communication, and human-factor studies in TCPS research. Moreover, we present our unique design and implementation of an integrated traffic-driving-network simulator (ITDNS). Finally, we discuss future enhancements that will promote best simulation practices for TCPS research.

Emerging Applications for Cyber Transportation Systems

Recent advances in connected vehicles and autonomous driving are going to change the face of ground transportation as we know it. This paper describes the design and evaluation of several emerging applications for such a cyber transportation system (CTS). These applications have been designed using holistic approaches, which consider the unique roles played by the human drivers, the transportation system, and the communication network. They can improve driver safety and provide on-road infotainment. They can also improve transportation operations and efficiency, thereby benefiting travelers and attracting investment from both government agencies and private businesses to deploy infrastructures and bootstrap the evolutionary process of CTS.

TASeT: Improving the Efficiency of Electric Taxis with Transfer-Allowed Rideshare

We consider a promising application for electric taxis (eTaxis) in transportation cyberphysical systems. The new rideshare scheme introduced herein takes into consideration both the limited battery of eTaxis and the user requirements. In the proposed eTaxi-sharing system, a passenger may share a taxi with others to enjoy a reduced fare and can potentially transfer from one eTaxi to another before reaching her destination, as long as her total trip time is within the maximum she specifies to be tolerable. Transfers are restricted to only take place at the designated (safe and convenient) battery charging stations scattered around the city. When an eTaxi comes to a charging station to pick up/drop off a transfer passenger, the eTaxis battery can be charged. In this paper, we address a new optimization problem called Transfer-Allowed Shared eTaxis (TASeT), whose goal is to schedule an eTaxis service and find optimal rideshare and transfer plans to maximize the system throughput in terms of the number of passengers served by the taxi service within a given time period. A mixed-integer programming (MIP) formulation is presented to solve TASeT, along with an efficient greedy heuristic. Aside from large-scale simulation, we also present a case study that utilizes real taxi traces collected from the city of Shanghai, China. Compared with the nontransferable taxi-sharing (NTT) case, our solution could improve the number of served passengers and shared travel distance by 22% and 37%, respectively, during rush hours.

Vehicle speed control algorithms for data delivery and eco-driving

Recently, V2V/V2I and connected vehicle (CV) technologies have received considerable research interest due to its potential breakthrough applications in eco-driving, road safety, surveillance, infotainment, and many more. In this paper, for the first time in literature, we address the problem of data-aware eco-driving. Specifically, we harnessed the latest V2V/V2I technologies to propose vehicle speed advisory system based on microscopic fuel model that simultaneously minimize fuel consumption and maximize probability of data delivery, thereby making the system flexible in handling sustainability and data dependent applications. Preliminary numerical studies are carried out demonstrating the significance of the problem and the proposed algorithms in terms of fuel and data downloading efficiencies.

A Partial Reality Experimental System for Human-in-the-Loop Testing of Connected and Automated Vehicle Applications: Development, Validation and Applications

This chapter describes a trans-disciplinary research initiative currently underway at the University at Buffalo, the State University of New York, which aims at developing next generation testing and evaluation platform for emerging Cyber Transportation Systems (CTS). Specifically, the work is developing an integrated traffic-driving-networking simulator (ITDNS), which allows for human-in-the-loop testing of Connected Vehicle (CV) and Automated Vehicle (AV) applications and their interactions. Following a brief discussion of ITDNS, its design rationale and unique advantages, the chapter proceeds to describe some of the on-going research designed to validate and extend ITDNS. The chapter also briefly describes our recent research which is taking advantage of the human-in-the-loop testing capabilities of ITDNS to evaluate a number of CV and AV applications such as eco-signals, Adaptive Cruise Control (ACC), and Co-operative, Integrated Vehicle Infrastructure Control (CIVIC).