Connected Testbeds for Connected Vehicles

This research team envisions that connected testbeds, i.e., remotely accessible testbeds integrated over a network in closed loop, will provide an affordable, repeatable, scalable, and high-fidelity solution for early cyber-physical evaluation of connected automated vehicle (CAV) technologies. Engineering testbeds are critical for empirical validation of new concepts and transitioning new theory to practice. However, the high cost of establishing new testbeds or scaling the existing ones up hinders their wide utilization. This project aims to develop a scientific foundation to support this vision and demonstrate its utility for developing CAV technologies. This application is significant, because a synergistic combination of connected vehicles and automated driving technologies is poised to transform the sustainability of our transportation system; automated driving technologies can leverage the information available from vehicle-to-vehicle (V2V) connectivity in optimal ways to dramatically reduce fuel consumption and emissions. However, state-of-the-art simulation and experimental capabilities fall short of addressing the need for realistic, repeatable, scalable, and affordable means to evaluate new CAV concepts and technologies. The goal of this project is to enable a high-fidelity integration of geographically dispersed powertrain testbeds and use this novel experimental capability to develop and test powertrain-level strategies to increase sustainability benefits of CAVs.

To realize this vision, the first objective of this research is to develop a cyber-integration interface to increase coupling fidelity in connected testbeds. This objective is pursued through a model-free predictor framework to compensate for network delays robustly. The second objective is to leverage this cyber-integration interface to create a connected testbed for CAVs. To this end, existing powertrain testbeds distributed across the University of Michigan campus and other institutions are leveraged. The third objective is to use this connected testbed for (i) developing strategies to minimize fuel consumption and emissions in CAV platoons of mixed vehicle types, including light-, medium-, and heavy duty vehicles, and (ii) understanding the limits of the benefits of connectivity due to various V2V communication issues.

The project accomplishments to date can be summarized as follows. (i) A predictor framework is under development to compensate for the network delays to increase the fidelity in closed-loop integration of remotely accessible testbeds over the network. Stability boundaries of the predictor have been derived analytically as a function of its design parameters and the network delay, and performance of the predictor has been characterized in the frequency domain. (ii) An optimal vehicle speed management strategy has been created to reduce fuel consumption without violating emissions performance in CAV platooning. Choice of optimization objective is studied to achieve good performance with short prediction horizon. (iii) A method has been developed to release the V2V sequential data in real time under a differential privacy constraint. Fuel consumption and emissions performance degradation due to differential privacy has been quantified in a scenario where the lead vehicle is following the standard FTP-75 drive cycle. (iv) A connected testbed has been created and the proposed predictor framework has been tested using a medium-duty engine with simulated network round-trip delays of 350ms. The fidelity of the connected testbed has been observed to increase significantly when predictors are used compared to the benchmark delayed case without predictors. In particular, the accuracy of the experimental results with predictors are improved by up to 93% compared to the delayed case.

This research area provides a rich space to advance the science of cyber-physical systems and demonstrate their impact, as it spans multiple disciplines including time delay systems, system dynamics and control, hardware-in-the-loop simulation, engine control, powertrain management, and communication networks. The potential of CAVs to improve the sustainability of transportation is an outstanding example of how cyber-physical systems can have a societal impact. The connected testbeds concept, on the other hand, can benefit not only CAVs, but also a wide range of applications such as telerobotics, haptics, networked control systems, earthquake engineering, manufacturing, and aerospace. It can open new doors for researchers to perform unparalleled integrative collaborations by enabling them to leverage each other's testbeds remotely. Furthermore, the project has so far graduated one PhD and one Post Doc, and two more female PhD students are being trained along with two undergraduate researchers. The project also provided development opportunity to a 7-12 STEM teacher.