Aircraft Collision Avoidance Systems (CAS) with Deep Corrections

This repository has four main components

• VICAS: a package for generating MDP table policies
• DeepCorrection: a package for learning deep corrections for MDP table policies
• CASIM: a multi-agent free flight airspace simulator
• Evaluation: tools for evaluating performance of collision avoidance systems

Requirements

This project uses Julia v0.6.4. Required packages are listed in JuliaPkgs.txt.

VICAS

Generate MDP table policies by running julia ./VICAS/src/gen_policy.jl. State space discretization and state transition sigma sampling schemes are defined in /VICAS/src/discretizations. The discrete MDP is solved by value iteration (VI). Notebooks in /VICAS/viz are used to interactively visualize policy slices. A sample of pairwise policy visualization is shown below:

DeepCorrection

Train deep corrections for MDP table policies (generated by VICAS) by running julia ./DeepCorrection/src/train.jl. Detailed algorithm implementation can be found in /DeepCorrection/DeepQLearning.jl/src. Use /DeepCorrection/src/viz_policy_multi.jl to visualize the corrected policy with multiple intruders.

CASIM

This is a package for simulating CAS in a free flight airspace. Various performance metrics are tracked and recorded. Run simulation using files in CASIM/benchmarking which specified various scenarios. Simulation animation can be generated by running CASIM/src/airspace_sim_animation.jl. A sample animation for simulation is shown below.

Tracked statistics can be found in /CASIM/src/Stats_module.jl. Encounter distribution from the statistics can be visualized using /CASIM/Encounter Distribution.ipynb.

Evaluation

This folder contains some evaluation tools.

• ResolutionRatio: evaluating the success rate of CAS in resolving encounters
• ResolutionTime: evaluating the time CAS use to resolve encounters
• Sensitivity: evaluating the alert sensitivity of CAS

• TrajectoryViz: visualizing flight trajectories under designed encounter scenarios with selected CAS

NoCAS	VICASClosest	CorrectedSector

Publication

S. Li, M. Egorov, and M. J. Kochenderfer, “Optimizing collision avoidance in dense airspace using deep reinforcement learning,” in Air Traffic Management Research and Development Seminar, 2019.