A Double-Level Model Checking Approach for an Agent-Based Autonomous Vehicle and Road Junction Regulations

Gleifer Vaz Alves,Michael Fisher,Louise Dennis

doi:10.3390/jsan10030041

Gleifer Vaz Alves, Michael Fisher + Show 1 more

Open Access

https://doi.org/10.3390/jsan10030041

Copy DOI

Abstract

Usually, the design of an Autonomous Vehicle (AV) does not take into account traffic rules and so the adoption of these rules can bring some challenges, e.g., how to come up with a Digital Highway Code which captures the proper behaviour of an AV against the traffic rules and at the same time minimises changes to the existing Highway Code? Here, we formally model and implement three Road Junction rules (from the UK Highway Code). We use timed automata to model the system and the MCAPL (Model Checking Agent Programming Language) framework to implement an agent and its environment. We also assess the behaviour of our agent according to the Road Junction rules using a double-level Model Checking technique, i.e., UPPAAL at the design level and AJPF (Agent Java PathFinder) at the development level. We have formally verified 30 properties (18 with UPPAAL and 12 with AJPF), where these properties describe the agent’s behaviour against the three Road Junction rules using a simulated traffic scenario, including artefacts like traffic signs and road users. In addition, our approach aims to extract the best from the double-level verification, i.e., using time constraints in UPPAAL timed automata to determine thresholds for the AVs actions and tracing the agent’s behaviour by using MCAPL, in a way that one can tell when and how a given Road Junction rule was selected by the agent. This work provides a proof-of-concept for the formal verification of AV behaviour with respect to traffic rules.

Highlights

The deployment of Autonomous Vehicles (AVs) in urban road networks is possible in the near future
In previous work [4], we presented the first version of SAE-Rules of the Road” (RoR) architecture, where we focused on the formalisation of the Road Junction rules using Linear Temporal Logic (LTL) and the first steps towards the implementation of a single rule using the agent programming language, GWENDOLEN [15].we extend the SAE-RoR architecture by adding an extra layer of modelling with timed automata and Model Checking using UPPAAL [16]
In our previous publications [3,4], we have presented the formalisation of the Road Junction rules in LTL and a partial implementation of Rule 170 in the GWENDOLEN language

Summary

Introduction

The deployment of Autonomous Vehicles (AVs) in urban road networks is possible in the near future. While the design of an AV should include sensors, cameras, software development, security protections, etc., it should take into consideration the assessment of the traffic rules within which the AV will operate. As highlighted by both Prakken [2] and Alves et al [3,4] these traffic rules are rarely considered in the design and assessment of AVs. 1.1. It is well known that such a task brings challenges, mainly since Highway Codes were not designed to operate alongside autonomous systems, and since the description of the rules is predominantly human-readable, and not machine-readable. The value of a clock denotes the amount of time that has elapsed since its last reset. Conditions which depend on clock values are called clock (or time) constraints

Objectives

Results

Conclusion