Motion Characteristics Analysis And Control Study Of Parafoil-Payload System

Parafoil-payload system can be used for precision airdrop and recovery of large spacecraft,which has a wide application prospect and gradually becomes the research hotspot of airdrop and recovery fields.The domestic research of parafoil-payload control is mainly based on 6 DOF model,which doesn’t consider the relative motion between payload and parafoil.Under this background,this dissertation builds the 8 DOF model,analyses the motion characteristics and studies the control of parafoil-payload system.The main researches are shown as follows:The dynamic models of the parafoil-payload system are built.The concept of added mass is explained and the computing method of parafoil-payload system’s added mass matrix is given.Then the 6 DOF motion equations of parafoil-payload system containing added mass matrix are derived.Based on the 6DOF model,the relative pitching and relative yaw between payload and parafoil are considered and the 8 DOF dynamic model is built.The basic motion characteristics and relative motion characteristics are studied.Based on the 6 DOF and 8 DOF motion equations,the gliding performance in both windless and windy conditions and turning performance of these two kinds of systems are contractively analyzed.In addition,the relative motion characteristics between payload and parafoil are studied.The lateral controller of parafoil-payload system is designed.The theory of PID control and the method of parameters setting are introduced.The theory of parafoil-payload system’s lateral control is clarified.Then,based on the 8 DOF model,the PID control is improved by increasing the yaw rate oscillation damper and ameliorating the integration element,and the lateral controller of parafoil-payload system is designed.Finally,the effectiveness of lateral controller is tested through simulating calculation.The path follower of parafoil-payload system is designed.The non-linear lateral control method of UAV guidance is applied to the tracking control of parafoil-payload system.The theory of non-linear lateral control method is introduced in detail and the influencing factors of lateral accelerated speed are explained.Based on the 8 DOF model,the path follower of parafoil-payload system is designed using the non-linear lateral control method,and the reference point’s effects on tracking control are analyzed.Finally,the effectiveness of path follower is tested through simulating calculation.The research accomplished in this paper provides theoretical basis for the optimization design of parafoil-payload system.The non-linear lateral control method presented in this paper provides reference for trajectory following of the parafoil-payload system and precise control of the large spacecraft recovery.