3D-Sonification for Obstacle Avoidance in Brownout Conditions

Helicopter brownout is a phenomenon that occurs when making landing approaches in dusty environments, whereby sand or dust particles become swept up in the rotor outwash. Brownout is characterized by partial or total obscuration of the terrain, which degrades visual cues necessary for hovering and safe landing. Furthermore, the motion of the dust cloud produced during brownout can lead to the pilot experiencing motion cue anomalies such as vection illusions. In this context, the stability and guidance control functions can be intermittently or continuously degraded, potentially leading to undetected surface hazards and obstacles as well as unnoticed drift. Safe and controlled landing in brownout can be achieved using an integrated presentation of LADAR and RADAR imagery and aircraft state symbology. However, though detected by the LADAR and displayed on the sensor image, small obstacles can be difficult to discern from the background so that changes in obstacle elevation may go unnoticed. Moreover, pilot workload associated with tracking the displayed symbology is often so high that the pilot cannot give sufficient attention to the LADAR/RADAR image. This paper documents a simulation evaluating the use of 3D auditory cueing for obstacle avoidance in brownout as a replacement for or compliment to LADAR/RADAR imagery

Recruitment and inhibitory action of hippocampal axo-axonic cells during behavior.

The axon initial segment of hippocampal pyramidal cells is a key subcellular compartment for action potential generation, under GABAergic control by the "chandelier" or axo-axonic cells (AACs). Although AACs are the only cellular source of GABA targeting the initial segment, their in vivo activity patterns and influence over pyramidal cell dynamics are not well understood. We achieved cell-type-specific genetic access to AACs in mice and show that AACs in the hippocampal area CA1 are synchronously activated by episodes of locomotion or whisking during rest. Bidirectional intervention experiments in head-restrained mice performing a random foraging task revealed that AACs inhibit CA1 pyramidal cells, indicating that the effect of GABA on the initial segments in the hippocampus is inhibitory in vivo. Finally, optogenetic inhibition of AACs at specific track locations induced remapping of pyramidal cell place fields. These results demonstrate brain-state-specific dynamics of a critical inhibitory controller of cortical circuits

Effects of Grid Cell Size in Altitude Control in an Augmented Reality Terrain Display

Helicopter pilot performance in degraded visual conditions may be improved through sensor fusion and an augmented reality display. A simulator experiment with 12 participants was done to test the effect of synthetic terrain grid cell size and helicopter heave dynamics on task performance and control behaviour in a terrain-following hill-climb task. An increase in grid cell size lowered task performance and increased control activity due to reduced optical information. Slower heave dynamics decreased task performance and led to a more prospective control strategy. It was concluded that an effective AR terrain display for altitude control can be designed independently from the vehicle dynamics.Control & Simulatio

Design and Evaluation of a Constraint-Based Head-Up Display for Helicopter Obstacle Avoidance During Forward Flight

This paper aims to reveal the effect of different display design principles in the helicopter domain. Two different obstacle avoidance support displays are evaluated during low-altitude, forward helicopter flight: a baseline Head-Up Display (HUD) is complemented either by a conventional advisory display, or a constraint-based display inspired by Ecological Interface Design. The latter has only been sparsely applied in the helicopter domain. It is hypothesized that the advisory display reduces workload, increases situation awareness, and improves performance measures in nominal obstacle avoidance situations, while the constraint-based display increases the resilience of the pilot-vehicle system towards unexpected, off-nominal situations. Twelve helicopter pilots with varying flight experience participated in an experiment in the SIMONA Research Simulator at Delft University of Technology. Contrary to expectations, the experiment revealed no significant effects of the displays on any of the dependent measures. However, there was a trend of decreasing pilot workload and increasing situation awareness when employing any of the support displays, compared to the baseline HUD. Pilots preferred the advisory display in nominal and the constraint-based display in off-nominal situations, reproducing similar findings from research in the fixed-wing domain. The relatively short time-frame and monotony of the control-task, an already cue-rich baseline HUD condition, and similarity between the displays possibly prohibited revealing larger differences between conditions. Future research will analyze the obstacle avoidance trajectories of this experiment, possibly revealing changes in control strategy caused by the displays, even when the lumped performance measures are similar. A follow-up experiment will focus on a longer task time-frame, more variable situations, and a truly ecological display to investigate the effect of applying Ecological Interface Design and different automation systems in the helicopter domain.Invited paperControl & Simulatio

Obstacle avoidance, visual detection performance, and eye-scanning behavior of glaucoma patients in a driving simulator: A preliminary study

The objective of this study was to evaluate differences in driving performance, visual detection performance, and eye-scanning behavior between glaucoma patients and control participants without glaucoma. Glaucoma patients (n = 23) and control participants (n = 12) completed four 5-min driving sessions in a simulator. The participants were instructed to maintain the car in the right lane of a two-lane highway while their speed was automatically maintained at 100 km/h. Additional tasks per session were: Session 1: none, Session 2: verbalization of projected letters, Session 3: avoidance of static obstacles, and Session 4: combined letter verbalization and avoidance of static obstacles. Eye-scanning behavior was recorded with an eye-tracker. Results showed no statistically significant differences between patients and control participants for lane keeping, obstacle avoidance, and eye-scanning behavior. Steering activity, number of missed letters, and letter reaction time were significantly higher for glaucoma patients than for control participants. In conclusion, glaucoma patients were able to avoid objects and maintain a nominal lane keeping performance, but applied more steering input than control participants, and were more likely than control participants to miss peripherally projected stimuli. The eye-tracking results suggest that glaucoma patients did not use extra visual search to compensate for their visual field loss. Limitations of the study, such as small sample size, are discussed.Biomechanical EngineeringMechanical, Maritime and Materials Engineerin