It will be important for astronaut pilots to overcome sensorimotor difficulties they may encounter should they switch from auto-pilot to manual control during lunar landing operations. The problems they may face include disorientation in the reduced gravity of the moon and difficulty in seeing and interpreting the moon's terrain.
Dr. Laurence R. Young and his colleagues are examining the nature of the anticipated sensorimotor problems and their impact on landing activities. The researchers also plan to develop advanced display countermeasures to overcome these limitations. The project will use lunar lander and helicopter simulators as part of the research.
Laurence R. Young, Sc.D.
Massachusetts Institute of Technology
Lunar landing depends on the selection and identification of an appropriate location that is level and free of hazards, along with a stable, controlled descent to the surface. During crewed landings, astronauts are expected to interact with automated systems, based upon improved terrain maps and sensor updates, to perform tasks such as manual re-designation of landing point, adjustment of descent trajectory or direct manual control. However, sensorimotor limitations, both vestibular and visual, are likely to interfere with performance and safety. This integrated project examines the nature of the anticipated spatial disorientation and terrain perception limits as they affect the transition from automatic to manual control and develops advanced display countermeasures to overcome these limitations.
Specific Aims There are four specific aims investigated in this multi-institution effort:
Examine the nature of anticipated sensorimotor difficulties (e.g., spatial disorientation, limits on terrain perception) as they affect the transition from automatic to manual control.
Develop and evaluate advanced display countermeasures for enhancing situation and terrain awareness and for overcoming performance limitations caused by reduced visibility associated with lunar lighting, terrain reflectivity and the absence of atmosphere utilizing Draper Laboratory's fixed-base lunar lander cockpit simulator for full human-in-the-loop evaluation.
Evaluate the effectiveness of the cockpit displays during human-in-the-loop manual control in the NASA Johnson Space Center (JSC) Tilt-Translation Sled (TTS) during "critical" and "hover" tasks testing the tilt-translation and tilt-gain illusions of altered acceleration sensitivity as it applies to lunar gravity following a period of weightlessness.
Perform a series of evaluations of the displays using the U.S. Army Aeromedical Research Laboratory's six-degree-of-freedom (6-DOF) helicopter simulator as a lunar landing analog for replicating lunar lighting and the various parameters associated with dust "brownout" conditions.
In our third year of work, we continued to make strides on Aims 1 and 2, while beginning work on Aims 3 and 4. For Aim 1, further analysis was completed on the experiment done in collaboration with Dr. Bilimoriaís group at NASA Ames Research Center. The experiment found that subjects reported misperceptions of vehicle orientation and horizontal velocity, even in the case where they were provided with a simulated out-the-window view. This was likely due to the small-field-of-view forward facing window which limited their complete perception. In Aim 2, we have developed an experimental testbed for lunar landing final approach and terminal descent in the Draper fixed-base simulator. This testbed simulation was used to test novel display prototypes including an achievability contour display, which provides the pilot information on which areas on the lunar surface are achievable given the remaining amount of fuel. In addition to the novel displays, a complete primary flight display (PFD) has been developed for simulation purposes. An experiment using these displays to land on the lunar surface was carried out in the Draper simulator. The achievability contour display was seen to improve subjective situation awareness and workload while improving the pilotís confidence in making landing point redesignations with a limited amount of fuel as compared to the auditory display type used during Apollo. Advanced blended control modes have been developed at Draper to assist the astronauts in the different phases of lunar landing.
For Aim 3, the Draper and MIT groupís display prototypes have been implemented in the NASA JSC Tilt-Translation Sled (TTS). The TTS will be used to simulate the sensorimotor challenges astronauts are expected to face during a lunar landing. In particular, the Critical Tracking Task (CTT) was implemented in the TTS and will be used to evaluate the advanced display countermeasures for their ability to improve pilot performance. For Aim 4, the US Army 6-DOF helicopter simulator has been modified to incorporate the properties of lunar dust blowback. An experiment has been designed to study the impact on dust blowback on pilot perceptions and landing performance. For the fourth year, we will continue our advance display countermeasure development in the Draper fixed-based simulator. These display prototypes will be tested in future experiments for their ability to improve pilot perceptions and performance during lunar landing. The NASA JSC TTS experiment will be completed, determining the effect of the sensorimotor challenges expected during lunar landing on pilot performance as well as the improvement expected using the display countermeasures. The Army 6-DOF motion simulator experiment will be completed to study the effect of dust blowback on astronaut perceptions.
Laurence R. Young, Sc.D.
Massachusetts Institute of Technology
Our goal is to determine the limits of human performance under likely landing conditions that may cause spatial disorientation. Appropriate roles can thereby be selected for humans and automated systems. This project will contribute to a better understanding of visual and vestibular conditions contributing to spatial disorientation during landing and the resulting effects on human manual control. We will have demonstrated display and control system interfaces to reduce pilot workload, improve situation awareness and mitigate spatial disorientation to ensure a safe crewed lunar landing. Finally, the work may also have terrestrial applications in mitigating the risk of helicopter accidents by suggesting new techniques to address problems associated with brownout during landing. In particular, the energy contour display being prototyped may have applications in helicopter flight planning, coping with brownout, as well as mission management aspects for guiding air-drops to locations given current environmental conditions (e.g., wind, air density).