A Survey of Collision Avoidance Methods for Unmanned Aircraft Systems

Threat detection and avoidance manoeuvres are complex fields of study. With the recent integration of Unmanned Aircraft Systems (UAS) in the airspace, Collision Avoidance (CA) methods have become a growing topic in Engineering. Commercial and large aircraft carry instrumentation onboard, such as Traffic Collision Avoidance System (TCAS), able to monitor in real-time the existence of threat and provide the most appropriate avoidance. However, this device in particular does not operate at any altitude below 1,000ft, also affecting general aviation. The lack of an onboard pilot is a challenge for unmanned systems that have to provide an equivalent level of safety as manned aircraft. This paper provides an overview of the Detect and Avoid (DAA) problem associated with the integration of UAS in the airspace; it aims to clarify misconceptions and other concepts. Special focus is given to CA methods since those techniques represent the avoidance procedure carried in the last stage before a collision and are particularly critical

Development, analysis, and implications of open-source simulations of remotely piloted aircraft

In recent years, the use of Remotely Piloted Aircraft (RPAs) for diverse purposes has increased exponentially. As a consequence, the uncertainty created by situations turning into a threat for civilians has led to more restrictive regulations from national administrations such as Transport Canada. Their purpose is to safely integrate RPAs in the current airspace used for piloted aviation by evaluating Sense and Avoid (SAA) strategies and close encounters. The difficulty falls on having to rely on simulated environments because of the risk to the human pilot in the piloted aircraft. In the first part of this research, the technical difficulties associated with the development and study of RPA computer models are discussed. It explores the rationale behind using Open-Source Software (OSS) platforms for simulating RPAs as well as the challenges associated with interacting with OSS at graduate student level. A set of recommendations is proposed as the solution to improve the graduate student experience with OSS. In the second part, particular challenges related to the design of OSS computer models are addressed. Based on: (1) the differences and similarities between piloted and RPA flight simulators and (2) existing Verification and Validation (V&V) approaches, a validation method is presented as a solution to the subject of developing fixed-wing RPAs in OSS environments. This method is used to design two flight dynamics models with SAA applications. The first computer model is presented in tutorial format as a case study for the validation procedure whereas the second computer model is specific for testing SAA strategies. In the last part, one of the designed RPAs is integrated into a computer environment with a representative general aircraft. From the simulated encounters, a diving avoidance manoeuvre on the RPA is developed. This performance is observed to analyze the consequences to the airspace. The implications of this research are seen from three perspectives: (1) the OSS challenges in graduate school are wide-spread across disciplines, (2) the proposed validation procedure is adaptable to fit any computer model and simulation scenario, and (3) the simulated OSS framework with an RPA computer model has served for testing preliminary SAA methods with close encounters with manned aircraft