Impact of Obstacle Sensor Choice on Preliminary Unmanned Helicopter Design, Sizing and Mission Performance in Obstacle Fields

Abstract

Through combining environmental sensing by the use of LIDAR, RADAR, stereo vision and other similar ranging sensors with automatic online flight path generation, unmanned helicopters gain the capability of automatic low-level flight in the presence of obstacles. Depending on sensor and planner choice, travel times will vary considerably for missions that includes low altitude flight segments in obstacle avoidance mode. The choice of sensors and necessary processing computers will also affect equipment weight and can adversely impact helicopter performance with respect to payload capability. For the purpose of preliminary helicopter design, the relationship between mission performance of a helicopter system in obstacle avoidance flight and resulting ideal helicopter size has not been looked at in the past. Therefore a simple helicopter preliminary sizing code for helicopters below 250 kg MTOW has been implemented and tuned through collecting size and weight data from similarly sized known helicopter configurations. A set of known, flight tested or simulated sensor suites has been selected and their performance in a reference helicopter mission has been simulated using a scenario which is based on the widely used Obstacle Field Navigation benchmark. Flight durations and velocities from these simulations are then used for preliminary vehicle sizing. For a reference mission, different resulting helicopter gross weights for each of the applied environment sensor types are presented and discussed.