Abstract
Due to their extensive use in various applications, helicopters need to be able to land in a variety of conditions. Typically, a helicopter landing gear system with skids or passive wheel-dampers is designed based on only one critical touchdown condition. Thus, this helicopter landing gear system may not perform well in different landing conditions. A landing gear system with magnetorheological (MR) dampers would be a promising candidate to solve this problem. However, a semi-active controller must be designed to determine the electrical current applied to the MR damper to directly manage the damping force. This paper presents a new skyhook controller, called the skyhook extended controller, for a helicopter with multiple landing gears equipped with MR dampers to reduce the helicopter’s acceleration at the center of gravity in off-normal landing attitude conditions. A 9-DOF simulation model of a helicopter with multiple MR landing gears was built using RECURDYN. To verify the effectiveness of the proposed controller, co-simulations were executed with RECURDYN and MATLAB in different initial pitch and roll angles at touchdown. The main simulation results show that the proposed controller can greatly decrease the peak and rms acceleration of the helicopter’s center of gravity compared to a traditional skyhook controller and passive damper.
Highlights
Helicopters are vertical take-off and landing aircraft able to hover, fly sideward, fly backward, and fly forward
In a semi-active controller, whose controllable damping force can be applied only in the opposite direction of the stroke velocity, the skyhook control law that is used for the ith landing gear is given as
To verify the effectiveness of the proposed controller in off-normal landing conditions, numerical simulations were executed with various initial pitch and roll angles
Summary
Helicopters are vertical take-off and landing aircraft able to hover, fly sideward, fly backward, and fly forward. Landing gears with skids or passive dampers are set up to improve safety and pilot comfort They are designed based on only one critical touchdown condition. The development of a helicopter landing gear system is necessary to reduce vibration as well as to improve safety and pilot comfort during touchdown in different landing scenarios. Jae-Up et al [5] applied a sky-hook control algorithm to improve the landing performance of a single helicopter landing gear with a magnetorheological (MR) damper. The main contribution of this study is to develop an easy-to-implement control algorithm for a helicopter with multiple landing gears equipped with MR dampers, which reduces the acceleration at the helicopter’s center of gravity under off-normal attitude conditions.
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