Development of an active suspension system for adaptive vibration control of helicopter seats

The high level vibration of helicopter flight can cause physiological damage to the aircrew and may lead to occupational health issues. This paper presents the development of an active suspension system for helicopter seats 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. In addition, an experimental modal analysis on a Bell-412 pilot seat equipped with a mannequin was carried out to investigate the seat and aircrew dynamics to identify critical vibration modes. Based on these tests, an active suspension system for the helicopter seat has been developed to be integrated on helicopter seats to reduce the vibration locally. This active suspension system included two stacked piezoelectric actuators installed on the seat frame as active struts to provide effective control authority to the critical mannequin vibration modes. A proof-of-concept active suspension system has been retrofitted on a full-scale Bell-412 pilot seat and the performance has been evaluated through extensive closed-loop control experiments performed on a mechanical shaker system. The mechanical shaker system was able to generate the representative vibration environment of the seat during flight. Test results demonstrated simultaneous suppression of the critical mannequin vibration modes and achieved significant global reduction of body vibration levels, which verified the effectiveness of the active suspension system for the helicopter seat to mitigate the vibration transmitted to the helicopter aircrew. The test results verified the effectiveness of an active suspension system implemented on the seat as a potential solution to reduce long term health issues faced by the helicopter aircrew.NRC publication: Ye