Simulation development of a forward sensor-enhanced low-altitude guidance system

Abstract

The requirement to operate aircraft at low-altitude near the terrain is common in the military community and essential for helicopters. The risk and crew workload in this flight regime is severe, with navigation, guidance, and obstacle avoidance demanding high attention. A guidance system relying on digitized terrain elevation maps has been developed that employs airborne navigation, mission requirements, aircraft performance limits, and radar altimeter returns to generate a valley-seeking, low-altitude trajectory between waypoints for display to the pilot. This system has been flight demonstrated to 150 ft above ground level altitude, and is primarily limited by the ability of the pilot to perform obstacle detection and avoidance. In this study, a wide field of view forward sensor has been modeled and incorporated in the guidance system for the purpose of relieving the pilot of the obstacle avoidance duty. The results of a piloted, motion-based simulation of this enhanced low-altitude guidance system is presented. Simulated flights to 50 ft altitude in the presence of obstacles were demonstrated while maintaining situational awareness and close tracking of the guidance trajectory.

In-flight collision avoidance controller based only on OS4 embedded sensors

“…Undoubtedly, some of the early pioneers in autonomous navigation for helicopters worked at NASA Ames Research Center. In the 1980's and 1990's they have published a series of papers highlighting some techniques developed for automatic Nap-Of-theEarth flights such as computer vision (Sridhar and Cheng, 1988), integration of active and passive sensors (Cheng and Sridhar, 1990), design of control strategies tested in 3D computer simulations Cheng and Lam, 1992;Zelenka et al, 1993). In the beginning, the authors developed 2D models of the environment and later on they extended the path search techniques to 3D in order to obtain a low-altitude guidance system for military helicopters.…”