Distributed Cooperative Control of Heterogeneous Multi-Vehicle Platoons

Abstract

Platooning, or controlled management of vehicle formation, enables multiple vehicles equipped with adaptive cruise control systems to drive behind one another with a specified inter-vehicle distance, acting together as one unit. In a platoon, the leading vehicle drives at a constant speed, independent of the following vehicles. The succeeding vehicles try to emulate this speed and maintain a following distance based on the most forward vehicle. To facilitate platoon implementation, an efficient control system that specifies to each vehicle the safe following distance and corresponding velocity is indispensable. Delays that are prevalent in throttle and brake response, as well as in vehicle control systems, can significantly increase the complexity of such an effective design, namely in that delays are often be unpredictable and time-varying. This thesis presents a distributed cooperative control system that considers heterogeneous vehicles to improve the safety and stability of multi-vehicle platoons under the presence of delays. Moreover, multiple control schemes including those based on adaptive cruise control and cooperative adaptive cruise control algorithms are evaluated through the development of several simulations. All simulations are designed pragmatically to consider speed limits and restrictions on the maximum acceleration and deceleration rates vehicles can attain. As such, heterogeneous vehicle dynamics, including that of acceleration and braking capacities, as well as actuation, sensor, and communication delays, are incorporated. Further, this thesis presents a novel distributed control scheme that compensates for time-varying delays under the Integral Quadratic Constraint (IQC) framework. The results exemplify that platoon stability is significantly influenced by the control structure and that the IQC based delay compensation allows for the preservation of platoon stability with relatively small inter-vehicle distances.