Traffic conflict reduction based on distributed stochastic task allocation

Abstract

The aim of this paper is to provide preliminary results on a traffic coordination framework based on stochastic task allocation. General trends and the predicted advent of personal aerial vehicles increase traffic rapidly, but current air traffic management methods admittedly cannot scale appropriately. A hierarchical system is proposed to overcome the problem, the middle layer of which is elaborated in this paper. This layer aims to enable stochastic control of traffic behaviour using a single parameter, which is achieved by applying distributed stochastic task allocation. The task allocation algorithm is used to allocate speeds to vehicles in a scalable way. By regulating the speed distribution of vehicles the conflict rates remain manageable. Multi-agent simulation results show that it is possible to control ensemble dynamics and together with that traffic safety and throughput via a single parameter. Using transient simulations the dynamic performance of the system is analysed. It is shown that the traffic conflict reduction problem can be transformed into a control design problem. The performance of a simple controller is also evaluated. It was shown that by applying the controller, quicker transients can be achieved for the mean speed of the system.

Analysis of the traffic conflict situation for speed probability distributions

“…This paper focuses on the analysis of the middle layer of this framework. Previous results indicate that conflict probabilities and their distribution are related to the airspace performance metrics [15,16]. Conflict rate (related to safety) and throughput (related to the average speed corrected for disruptions) describe system-level behaviour and enable overall airspace design.…”

On the underlying dynamics of traffic conflicts related to stochastic behaviour

“…How the time threshold can be selected and a sensitivity analysis can be found in a previous publication on the topic. 25 The exact relationship between dynamics, equipage and conflict time thresholds should be subject to future research.…”

“…This algorithm has been used previously by the authors in the context of multi-agent simulations. 25 The desired distribution is defined in terms of a few parameters, which can be regarded as decision variables. The aim of the top level is to optimise a cost function by tuning these decision variables.…”

“…Simulation setup and results are explained in detail in another publication by the authors. 25 The calculated safety metric was then normalised with the number of agents, simulation area and the radius of the sensing range (nagent A rS). The numerical results can be found in Table A2.…”

“…Applicability and performance of several stochastic task allocation methods in terms of distribution distance and transient characteristics were previously analysed using multi-agent simulations. 25 These algorithms can be used to drive an ensemble to a given probability distribution. 26 It was also shown by Jang et al 29 that organisation is possible using only local information.…”