American Institute of Aeronautics and Astronautics 1Development of a Sense and Avoid System Mr. James Utt* Defense Research Associates, Inc., Beavercreek, OH 45431 Dr. John McCalmont† Sensors Directorate, Air Force Research Laboratory (AFRL/SNJT), Wright Patterson AFB, OH 45433 Mr. Mike Deschenes‡ Defense Research Associates, Inc., Beavercreek, OH 45431 Remotely Operated Aircraft (ROAs) currently do not have convenient access to civil airspace due to their inability to provide an onboard capability to “see and avoid” air traffic. Defense Research Associates, Inc. and AFRL/SNJT have developed affordable technology based on silicon charge couple device sensors and passive moving target detection algorithms. Previously, a flight demonstration proved real-time implementation of complex detection and tracking algorithms with multiple sensors providing a wide field of regard was feasible. This paper documents lessons learned from that demonstration, subsequent improvements made to the prototype system, resulting performance improvements, and planned next steps. I. Introduction Federal Aviation Administration (FAA) Regulation 7610.4 states remotely operated aircraft must provide an “…equivalent level of safety, comparable to see-and-avoid requirements for manned aircraft” in order to operate like manned aircraft in the National Air Space (NAS). The capability must be effective against all air traffic, with or without active, transponder-based collision avoidance systems. Currently, no ROA “see and avoid” capability exists. ROAs operating in the NAS must obtain Certificates of Authorization, a cumbersome process, and/or use either chase planes or ground-based observers. Plans to deploy Predator ROAs in National Guard and Homeland Security applications increase the urgency of the need for a solution. The Air Force Research Laboratories’ Sensors Directorate (AFRL/SN), and Defense Research Associates, Inc. (DRA) have developed technology called Sense and Avoid (SAA) that has the potential to meet the FAA’s “see and avoid” requirement. The first step in developing SAA was to reduce the phrase “… equivalent level of safety…” to engineering performance requirements, the most difficult of which was detection range. DRA used a validated AFRL/SN human vision model called OPEC and custom simulation software to numerically quantify the required detection ranges along with actual human capability for a complex set of scenario parameters developed in conjunction with the Air Force Aeronautical Systems Center, Air Force Air Combat Command, and industry [McCalmont et al 2002, Bryner et al 2003]. Next, the team examined a variety of potential technologies including radar, infrared, and silicon band sensors. The team selected an approach based on silicon sensors and complex image processing algorithms based on detecting motion of intruder aircraft relative to the background scene. A series of flight demonstrations using a small field of regard sensor and post-processing of recorded sensor data verified predictions that SAA technology could meet Global Hawk and Predator requirements, as shown by [McCalmont et al 2002]. Next, the team built a real time implementation of the detection and tracking algorithms using field programmable gate array chips and microprocessors operating with multiple sensors to increase system field of regard. Another series of ROA surrogate flight demonstrations verified real time SAA implementation was practical [Deschenes et al 2004] and provided some important “lessons learned.” Based on these demonstrations, the Air Force funded the AFRL team to undertake development of the technology into a product starting in 2005 with subsequent transition to the field starting in 2007 via a phased Advanced Technology Demonstration (ATD) program [McCalmont et al 2005]. * Vice President, Systems Development, 3915 Germany Lane, Suite 102, Beavercreek, OH 45431. † Threat Warning Team Leader, AFRL/SNJT, 3050 C Street, Hangar 4B, Wright Patterson AFB, OH 45433. ‡ Engineering Team Leader, Systems Development, 3915 Germany Lane, Suite 102, Beavercreek, OH 45431. Infotech@Aerospace26 - 29 September 2005, Arlington, VirginiaAIAA 2005-7177Copyright © 2005 by the American Institute of Aeronautics and Astronautics, Inc.The U.S. Government has a royalty-free license to exercise all rights under the copyright claimed herein for Governmental purposes.All other rights are reserved by the copyright owner.American Institute of Aeronautics and Astronautics 2II. Review of Real-Time Demonstration Hardware and Methodology The Sense and Avoid (SAA) concept uses several key technologies: CCD sensors, new discrimination algorithms, and field programmable gate arrays (FPGAs). The SAA concept is to use three sensors to provide adequate non-cooperative target collision avoidance protection. The sensors are high resolution (megapixel), low cost, digital video cameras available in the commercial market. The selected sensor provides high spatial resolution (~0.5 milliradian) while maintaining a large field of view. Detection and tracking algorithms characterize global scene motion, Sense objects moving with respect to the scene, and classify the objects as threats or non-threats. The demonstration utilized the six-seat, twin-engine Aero Commander aircraft as a surrogate ROA. The Beech Bonanza shown in the same figure was the intruder aircraft. The processing and data recording equipment were installed in a custom-designed rack, which replaced the middle row of seats in the Aero Commander. The aircraft were flown toward each other in a series of near-collision “engagements.” A 500’ altitude separation was maintained for safety purposes. Engagements concentrated on nose-on geometries since this was the most challenging (smallest profile of the approaching aircraft and longest detection range requirement). Figure 1 shows the flight demonstration hardware assets; the hardware shown in Figure 1 was christened the Air Traffic Detection Sensor System (ATDSS). Figure 1. Real-Time Demonstration Assets Including ATDSS Hardware III. Lessons Learned The real-time multi-sensor demonstration hardware functioned reliably during the demonstration thereby successfully achieving the stated demonstration objectives. However, the demonstration hardware also produced thousands of false tracks during the relative short cumulative flight