Optimisation-based coordination of connected, automated vehicles at intersections

In this paper, we analyse the performance of a model predictive controller for coordination of connected, automated vehicles at intersections. The problem has combinatorial complexity, and we propose to solve it approximately by using a two stage procedure where (1) the vehicle crossing order in which the vehicles cross the intersection is found by solving a mixed integer quadratic program and (2) the control commands are subsequently found by solving a nonlinear program. We show that the controller is persistently safe and compare its performance against traffic lights and two simpler optimisation-based coordination schemes. The results show that our approach outperforms the considered alternatives in terms of both energy consumption and travel-time delay, especially for medium to high traffic loads

An Interior Point Algorithm for Optimal Coordination of Automated Vehicles at Intersections

In this paper, we consider the optimal coordination of automated vehicles at intersections under fixed crossingorders. We state the problem as a Direct Optimal Control problem, and propose a line-search Primal-Dual Interior Point algorithm with which it can be solved. We show that the problem structure is such that most computations required to construct the search- direction and step-size can be performed in parallel on-board the vehicles. This is realized through the Schur-complement of blocks in the KKT-matrix in two steps and a merit-function with separa- ble components. We analyze the communication requirements of the algorithm, and propose a conservative approximation scheme which can reduce the data exchange. We demonstrate that in hard but realistic scenarios, reductions of almost 99% are achieved, at the expense of less than 1% sub-optimality

Optimal coordination of automated vehicles at intersections with turns

In this paper we address the problem of co- ordinating automated vehicles at intersections, with a spe- cial focus on turning maneuvers. The inclusion of rear-end collision avoidance constraints into the problem is decided during turning maneuvers by a smooth function of the vehicle state, rather than integer variables. Moreover, curvature-based acceleration constraints are introduced, which limit the velocity of the vehicle during the turn, and a term in the objective function accounts for passenger comfort. We discuss how the coordination problem is formulated as a nonlinear program and show though simulations that for practical problem instances the proposed approximation is either exact or introduces very little conservativeness