Publications
Position validation strategies using partially observable Markov decision processes
Summary
Summary
The collision avoidance system that is currently deployed worldwide relies upon radar beacon surveillance. With its broad deployment over the next decade, aviation surveillance based on Automatic Dependent Surveillance-Broadcast (ADS-B) reports may reduce the need for frequent beacon interrogation over the communication channel, but there is a risk of ADS-B...
Analysis of open-loop and closed-loop planning for aircraft collision avoidance
Summary
Summary
Open-loop planning has been a popular approach for developing aircraft collision avoidance systems. Open-loop planning computes a future plan to follow without anticipation of how future observations can affect the future course of action. Closed-loop planning, in contrast, takes into account the ability to react to future information. This paper...
Hazard alerting based on probabilistic models
Summary
Summary
Hazard alerting systems alert operators to potential future undesirable events so that action may be taken to mitigate risk. One way to develop a hazard alerting system based on probabilistic models is by using a threshold-based approach, where the probability of the undesirable event without mitigation is compared against a...
Accounting for state uncertainty in collision avoidance
Summary
Summary
An important consideration in the development of aircraft collision avoidance systems is how to account for state uncertainty due to sensor limitations and noise. However, many collision avoidance systems simply use point estimates of the state instead of leveraging the full posterior state distribution. Recently, there has been work on...
Collision avoidance system optimization with probabilistic pilot response models
Summary
Summary
All large transport aircraft are required to be equipped with a collision avoidance system that instructs pilots how to maneuver to avoid collision with other aircraft. Uncertainty in the compliance of pilots to advisories makes designing collision avoidance logic challenging. Prior work has investigated formulating the problem as a Markov...
Unmanned aircraft collision avoidance using continuous-state POMDPs
Summary
Summary
An effective collision avoidance system for unmanned aircraft will enable them to fly in civil airspace and greatly expand their applications. One promising approach is to model aircraft collision avoidance as a partially observable Markov decision process (POMDP) and automatically generate the threat resolution logic for the collision avoidance system...
A new approach for designing safer collision avoidance systems
Summary
Summary
The Traffic Alert and Collision Avoidance System (TCAS) has been shown to significantly reduce the risk of mid-air collision and is currently mandated worldwide on all large transport aircraft. Engineering the collision avoidance logic was a very costly undertaking that spanned several decades. The development followed an iterative process where...
Partially-controlled Markov decision processes for collision avoidance systems
Summary
Summary
Deciding when and how to avoid collision in stochastic environments requires accounting for the likelihood and relative costs of future sequences of outcomes in response to different sequences of actions. Prior work has investigated formulating the problem as a Markov decision process, discretizing the state space, and solving for the...
Aircraft collision avoidance using Monte Carlo real-time belief space search
Summary
Summary
The aircraft collision avoidance problem can be formulated using a decision-theoretic planning framework where the optimal behavior requires balancing the competing objectives of avoiding collision and adhering to a flight plan. Due to noise in the sensor measurements and the stochasticity of intruder state trajectories, a natural representation of the...
Robust airborne collision avoidance through dynamic programming
Summary
Summary
The Traffic Alert and Collision Avoidance System (TCAS) uses an on-board beacon radar to monitor the local air traffic and logic to determine when to alert pilots to potential conflict. The current TCAS logic was the result of many years of development and involved the careful engineering of many heuristic...