(Georgia Institute of Technology, 2022-06-22)
Walters, Robert
Augmented Reality Cueing Methodologies For Rotorcraft Shipboard Landings
Robert Walters
159 Pages
The helicopter-ship interface is one of the most challenging flight regimes in which pilots operate. Several factors make this flight regime complicated, such as the relative motion between the aircraft, the ship, and the sea, and also the air wake turbulence and the confined nature of the landing zone. Degraded visuals conditions such as sea spray, adverse weather, and poor lighting conditions compound the other difficulties. The high pilot workload from these factors can lead to a loss of situational awareness which can result in catastrophic aircraft accidents. Currently fielded cueing systems are not up to this challenge.
To reduce pilot workload and improve situational awareness and performance, better pilot cueing is required. This dissertation investigated the extent to which augmented reality cueing utilizing modern rendering techniques reduces pilot workload and improves situational awareness and performance. This was done by supporting a ‘head-up, eyes-out’ ego-centric interface philosophy. The cueing systems sought to incorporate common pilot mission task elements into the design. Changes to both the path preview and trajectory prediction were studied. The visual elements of the cues were displayed as if they were comprised of three dimensional physical objects.
Operational flexibility in high workload environments is key to pilot task accomplishment. The ability to dynamically generate on demand flight trajectories that pilots could manually fly was another goal of this dissertation. The mathematical framework of Bézier curves was utilized for trajectory planning to ensure the paths satisfy the needs of the pilot, the certification authorities, and the specific mission task element.
Four different cueing paradigms were programmed into the Georgia Tech reconfigurable rotorcraft flight simulator. These paradigms were; a 2D Head Up Display (HUD), a Flight Lead Cueing System (FLCS), a Tunnel In the Sky (TIS), and a 3D Flight Path Marker (FPM). The cues were then evaluated using objective measures and pilot workload surveys in a series of Pilot-in-the-Loop (PIL) studies.
A total of twenty pilots took part in the study. Seven pilots participated in phase 1, three in phase 2, and ten in phase 4. Phase 3 included only data flown by the author and LTC Joe Davis due to pandemic related travel restrictions preventing the use of additional external pilots. Most PIL studies have a relatively low number of participants, in the range of two to six. In order to gain statistical significance from a relatively low number of participants the participants are asked to repeat the task several times. For example the pilots in phase 4 each flew a total of 54 approaches. The central limit theorem, states that a distribution will be approximately normally for large sample sizes, where a sample size over 30 is considered large. Consequently even when the data is divided to look at a specific cueing condition or starting location the large sample size criteria is met and we can gain statistical insight.
Bézier curves provide a feasible method to dynamically generate landing trajectories for pilots to fly by hand. The methods are numerically stable and execute fast enough that there is minimal perceptual latency to the pilot. The pilots were able to follow the generated trajectories with sufficient accuracy both laterally and vertically. The paradigm shift of using 3D AR cueing which the pilots mentally process as signals instead of signs or symbols resulted in reduced workload and had performance that was the same or better than traditional cueing methods.