Production of isometric forces during sustained acceleration

Area of Science:

• Human Factors Engineering
• Aerospace Physiology
• Motor Control

Background:

• Pilot performance in high-performance aircraft relies on precise force application to controls.
• Exposure to high G-force acceleration during flight can potentially degrade this fine motor skill.
• Understanding the impact of acceleration on pilot control is crucial for flight safety.

Purpose of the Study:

• To investigate the extent to which sustained acceleration degrades a pilot's ability to finely control forces.
• To quantify the effects of different G-force levels on isometric force production.
• To identify potential mechanisms underlying acceleration-induced deficits in motor control.

Main Methods:

• Twelve healthy non-pilot volunteers participated in centrifuge-based experiments.
• Participants performed isometric joystick tasks at 1 G, 1.5 G, and 3 G (+Gz orientation).
• Force vector magnitude and direction were visually commanded and produced using an isometric joystick.

Main Results:

• Sustained acceleration significantly increased the magnitude of produced isometric force.
• Maximum produced force was approximately 2 N higher at 1.5 G and 10 N higher at 3 G compared to 1 G.
• The effect of acceleration on force magnitude was consistent across force levels but varied with direction.

Conclusions:

• Acceleration degrades the control of isometric force production in a manner relevant to aviation.
• Potential causes include misinterpretation of the gravitoinertial environment and degraded proprioceptive feedback.
• Excessive force production due to acceleration may compromise the safe operation of high-performance aircraft.