Development of Adaptive Helicopter Seat for Aircrew Vibration Reduction

Abstract

The high level vibration of helicopter flight can cause physiological harm to the aircrew and may lead to occupational health issues. This article presents the development of an adaptive helicopter seat mount to reduce the vibration levels transmitted to the aircrew body. Flight test on a Bell-412 helicopter was conducted to measure the aircrew body vibration levels and vibration transmission through the seat structures. Experimental modal analysis on a Bell-412 co-pilot seat equipped with a mannequin was carried out to investigate the seat/aircrew dynamics and identify critical vibration modes. Based on observations from the configuration, an adaptive helicopter seat mount has been developed. Two stacked piezoelectric actuators were installed on the seat frame as active struts to provide effective control authority to the critical mannequin vibration modes. A proof-of-concept adaptive helicopter seat has been retrofitted on a full-scale Bell-412 co-pilot seat and the performance has been evaluated through extensive closed-loop control experiments. Test results demonstrated simultaneous suppression of the critical mannequin vibration modes and achieved significant global reduction of the body vibration levels, which verified the effectiveness of the adaptive helicopter seat mount concept for helicopter aircrew vibration reduction applications.