Force Distribution-Based Control Strategy of Landing Gear for the Unmanned Helicopter Landing on the Inclined Surface

The unmanned helicopter plays an important role in the fields of cargo transportation and rescue missions. Due to the limitation of the traditional landing gear structure, the unmanned helicopter has more stringent requirements on the landing terrain. In order to improve the ability to land on the inclined surface for the unmanned helicopter, a novel control strategy of the landing gear based on contact force distribution algorithm is proposed. The overall of landing process includes the desired position tracking stage, the following stage and the attitude adjusting stage. By obtaining the desired acceleration according to the landing and attitude correcting curve of the fuselage, and calculating the desired force based on contact force distribution algorithm, the adaptive motion and trajectory tracking of the landing gear during the landing process has been realized. The simulation results have demonstrated the effectiveness of the strategy when the unmanned helicopter with the initial roll angle of -3 degrees and pitch angle of 3 degrees lands on the inclined surface of 7.07 degrees. In the future, the control strategy can provide a reference for the dynamic landing of the unmanned helicopter while at sea.