Dynamic Modeling And Control Technology Research On The Transport During Heavy Cargo Airdrop

When a transport performs a heavy cargo airdrop task, first of all, the transport arrives at thepredetermined area and adjusts itself to a stable flight state, and then the towing parachute is openedand at the same time the heavy cargo is unlocked, and lastly the cargo moves towards the hatch alongthe slide rail in the effect of the towing parachute. The altitude and attitude of the transport deviatefrom original flight state in the effect of the force and moment produced by the cargo moving inside.An improper control might make the cargo far away from the predetermined area, even result in afatal crash.This paper establishes a dynamics model of the transport-cargo system for this special process.Because of the cargo’s movement during the heavy cargo airdrop task, the motion equations of thetransport are different from the general condition. The transport-cargo system is considered as atwo-body system, and a transport-cargo coupling dynamics model is established based on vectormechanics.The motion equations of the transport are complicated and non-linear, and the altitude andattitude of the transport is disturbed by the cargo’s harmful impact, and therefore, two robustcontrollers based on different control theories are designed to weaken the disturbance of thetransport’s attitude, and to ensure the flight safety of the transport in the heavy cargo airdrop process.Firstly, a H robust controller is designed for the heavy cargo airdrop process. The motionequations of the transport are nonlinear and the H control theory is a linear system theory, so thenonlinear dynamics model is linearized based on small disturbance assumption in the trim condition.After that, a H robust controller is specially established for the linear system. Secondly, a class ofnonlinear control strategies, sliding mode variable structure control, is used, and a sliding modevariable structure controller is designed to control the transport’s state during the heavy cargo airdroptask. Lastly, the numerical simulate experiments are accomplished to verify that the designed controlstrategies could weaken the disturbance of the transport’s attitude, and could ensure the flight safetyof the transport in the heavy cargo airdrop process, and the summary and comparison of the twodifferent controllers are completed.