Quadratic approximation based heuristic for optimization-based coordination of automated vehicles in confined areas

A Two-Stage MIQP-Based Optimization Approach for Coordinating Automated Electric Vehicles in Confined Sites

“…In our previous work [31] and [32], we proposed optimization-based heuristics to coordinate vehicles in confined sites, ensuring conflict avoidance in all MUTEX zones. This paper introduces a control strategy that extends the optimal control formulation from [32] to address the inclusion of charging zone MUTEX constraints. To capture the intricacies of the charging process, we incorporate models that represent electric vehicles' powertrain dynamics.…”

“…This task is non-trivial and arises from industry feedback highlighting the necessity to accommodate electric vehicles. While the heuristic idea and general approach remain consistent with [32], we extend the framework to effectively handle the coordination of vehicles within charging zones and during the charging process. By incorporating charging MUTEX zones, our approach becomes more comprehensive and applicable.…”

“…As stated in [32], for confined site optimization, it is beneficial to optimize the trajectories of the vehicles over their full paths. However, the time it takes a vehicle to traverse a path is dependent on the solution, and not known a-priori.…”

“…As explained in [31], [32], finding a solution to MINLP problems is known to be difficult, especially when the constraints or the objective function are non-convex [37]. Therefore, a common procedure is to apply an approach where the integer part of the solution is obtained first using a heuristic, and the continuous part of the solution thereafter is obtained by solving the nonlinear program (NLP) that results from fixing the integers to the values found with the heuristic.…”

“…Therefore, a common procedure is to apply an approach where the integer part of the solution is obtained first using a heuristic, and the continuous part of the solution thereafter is obtained by solving the nonlinear program (NLP) that results from fixing the integers to the values found with the heuristic. The heuristic that is used is similar to that of [32] which approximates the integer part of the solution of ( 26) by solving a Mixed Integer Quadratic Problem (MIQP). With the obtained integer solution, the state and control trajectories are calculated by solving the "fixed-order coordination" NLP, i.e., Problem 2 with fixed crossing orders O I , O MS , O CS .…”