Multi-objective adaptive cruise control (ACC) algorithm for cooperative ACC platooning

With the rapid progress of the automated highway system, the issue of platoon stability, which might significantly affect highway traffic characteristics, such as traffic efficiency, traffic capacity, and traffic safety, has attracted considerable attention. A string of vehicles equipped with adaptive cruise control (ACC) and moving longitudinally in an automated manner is regarded as an autonomous vehicle platooning system. During car following, the quality of the ride could be poor and rear-end collisions could occur, particularly if the spacing and velocity errors are amplified to some extent as they propagate upstream. Research on platoon stability has been the focus of significant interest. However, a method to coordinate multiple sub-objectives dynamically during autonomous vehicle platooning against multiple traffic scenarios has not yet been developed. In this study, a multi-objective ACC algorithm for cooperative adaptive cruise control (CACC) platooning based on vehicle-to-vehicle (V2V) real-time communication technology, which enabled the interconnection of vehicles within a limited range to share vehicle position and motion state information, was thus proposed. The quantization of homogeneous and heterogeneous platoon stability was analyzed on the basis of the Lyapunov stability theory. Furthermore, on the basis of the model predictive control framework, the coordination among various conflicting sub-objectives, such as driver-desired car-following response, rear-end safety, platoon stability, and platoon overall quality, was comprehensively considered. Then, by utilizing a quadratic cost function with linear multi-constraints, the design of the multi-objective CACC was transformed into the convex quadratic programming problem with multiple constraints. The comparative simulations show that the I/O constraints and slack relaxation of platoon control are strict, indicating that platoon stability is easily affected by certain factors, such as time gap, platoon size, sub-objective weight coefficient, transient traffic scenarios, and heterogeneous features. Thus, rear-end safety and platoon stability should be prioritized to guarantee the overall quality of the platoon.