Robert Hult

An approximate solution to the optimal coordination problem for autonomous vehicles at intersections

In this paper, we address the problem of optimal and safe coordination of autonomous vehicles through a traffic intersection. We state the problem as a finite time, constrained optimal control problem, a combinatorial optimization problem that is difficult to solve in real-time. A low complexity computational scheme is proposed, based on a hierarchical decomposition of the original optimal control formulation, where a central coordination problem is solved together with a number of local optimal control problems for each vehicle. We show how the proposed decomposition allows a reduction of the complexity of the central problem, provided that approximated parametric solutions of the local problems are available beforehand. We derive conditions for the construction of the parametric approximations and demonstrate the method with a numerical example.

Cooperative receding horizon conflict resolution at traffic intersections

In this article, we consider the problem of coordinating a number of vehicles crossing a traffic intersection. The proposed solution is based on a receding horizon formulation with a pre-defined decision order. In this approach, local problems are formulated for each vehicle, which are divided into a finite-time optimal control problem, where collision avoidance is enforced as terminal constraints, and an infinite horizon control problem, which can be solved offline. Feasibility conditions for a given decision sequence are also derived and simulation results are presented.

Communication analysis for centralized intersection crossing coordination

Coordination of autonomous cooperative vehicles is an important challenge for future intelligent transportation systems. In particular, coordination to cross intersections captures the inherent and connected challenges among control and communication. While intersection coordination and vehicular wireless communication have both received extensive treatment in their respective communities, few works consider their interaction. We provide a communication system analysis for the specific problem of centralized intersection crossing coordination, leading to design guidelines for both uplink (whereby vehicles send intentions to the central controller) and downlink (where the controller prescribes vehicles of safe control actions).

Design and Experimental Validation of a Cooperative Driving Control Architecture for the Grand Cooperative Driving Challenge 2016

In this paper, we present the cooperative driving system developed by the Chalmers car team for the grand cooperative driving challenge 2016. This paper gives an overview of the system architecture and describes in detail the communication, signal processing, and decision-making sub-systems. Experimental results demonstrate the system’s performance and operation according to the rules and requirements of the competition.

Primal decomposition of the optimal coordination of vehicles at traffic intersections

In this paper we address the problem of coordinating automated vehicles at intersections, which we state as a constrained finite horizon optimal control problem. We present and study the properties of a primal decomposition of the optimal control problem. More specifically, the decomposition consists of an upper problem that allocates occupancy time-slots in the intersection, and lower-level problems delivering control policies for each vehicle. We investigate the continuity class of the upper problem, and show that it can be efficiently tackled using a standard sequential quadratic programming and that most computations can be distributed and performed by the participating vehicles. The paper is concluded with an illustrative numerical example.