<title>Affordable MMW aircraft collision avoidance system</title>

Abstract

Collision avoidance is of concern to all aircraft, requiring the detection and identification ofhazardous terrain or obstacles in sufficient time for clearance maneuvers. The collision avoidance requirement is even more demanding for helicopters, as their unique capabilities result in extensive operations at low-altitude, near to terrain and other hazardous obstacles. To augment the pilot's visual collision avoidance abilities, some aircraft are equipped with "enhanced-vision" systems or terrain collision warning systems. Enhanced-vision systems are typically very large and costly systems that are not very covert and are also difficult to install in a helicopter. The display is typically raw images from infrared or radar sensors, and can require a high degree of pilot interpretation and attention. Terrain collision warning systems that rely on stored terrain maps are often of low resolution and accuracy and do not represent hazards to the aircraft placed after map sampling. Such hazards could include aircraft parked on runway, man-made towers or buildings and hills. In this paper, a low cost dual-function scanning pencil-beam, millimeter-wave (MMW) radar forward sensor is used to determine whether an aircraft's flight path is clear of obstructions. Due to the limited space and weight budget in helicopters, the system is a dual function system that is substituted in place of the existing radar altimeter. The system combines a 35GHz forward looking obstacle avoidance radar and a 4.3 GHz radar altimeter. The forward looking 35 GHz 3-dimensional radar's returns are used to construct a terrain and obstruction database surrounding an aircraft, which is presented to the pilot as a synthetic perspective display. The 35GHz forward looking radar and the associated display was evaluated in ajoint NASA Honeywell flight test program in 1996. The tests were conducted on a NASA/Army test helicopter. The test program clearly demonstrated the systems potential usefulness for collision avoidance.

SAPIR collision alert system as part of IR MWS suite for helicopter fleets

“…While neither technology provides an ideal all encompassing solution, each technology has its strong and weak points and hence complementary approach can also be adopted to provide a more robust and cost effective concerted system approach. The technologies we review are - Other airborne applicable detection technologies such as LADAR [6] and MMW [7] are mostly focused on obstacle detection alert such as power lines/poles and terrain extended hazards. This focus entails systems with limited field of regard centered on flight direction vector thus limiting the CA solution in terms of platform peripheral coverage that will be needed for formation flight and general traffic scenarios.…”

Automatic Censoring CFAR Detector Based on Ordered Data Difference for Low-Flying Helicopter Safety

“…Helicopters, used in law enforcement, fire fighting, medical evacuation, civil emergencies, search and rescue and new/traffic reporting, are often required to fly at low altitudes of limited visibility [ 1 , 2 ]. Obstacles in the flight path or close to it often pose a significant threat to low-flying helicopters [ 3 ].…”

Image processing and fusion to detect navigation obstacles

“…However, the coverage of the lidar was not enough as long as the laser emission power was kept in 'eye safe" level. A scanning beam Millimeter-Wave radar [4] and a synthetic aperture radar based on rotating antennas [5] were presented as forward looking sensors. Both of them looked very promising in the future.…”