Head and helmet biodynamics and tracking performance in vibration environments

Area of Science:

• Aerospace Engineering
• Human Factors
• Biomechanics

Background:

• Vibration exposure in aircraft can affect aircrew performance and safety, particularly when using helmet-mounted equipment.
• Understanding head and helmet dynamics under vibration is crucial for optimizing equipment design and operational safety.

Purpose of the Study:

• To quantify the effects of head orientation and helmet center-of-gravity (CG) on head/helmet biodynamics.
• To assess the impact of these factors on aircrew tracking performance during vibration.

Main Methods:

• Tested three head orientations (including two off-axis) and three helmet CGs.
• Measured head, helmet, and slippage displacements, along with tracking error and time-on-target.
• Exposed participants to aircraft buffeting and quasi-random vibration.

Main Results:

• Off-axis orientations significantly increased head, helmet, and slippage displacements.
• Helmet instability was greatest in pitch for forward and upward head orientations.
• Performance degradation was higher with the 'Side' orientation during buffeting, linked to specific CGs and head pitch.

Conclusions:

• High off-boresight head movements can impair visual performance in operational vibration environments.
• Helmet pitch instability may affect exit pupil design, and weight distribution is critical for biodynamics and performance.