Summary For achieving the accurate trajectory tracking of flexible wing unmanned aerial vehicle in complicated missions, especially vertical component, a feedforward compensation unit–based active disturbance rejection control (ADRC) is proposed. In ADRC, internal dynamics and influence total will be estimated dynamically compensated by extended state observer (ESO). It puts very high request on observation ability ESO with unpredictable external disturbance, complex coupling influence,...

Shock-train transitions in simplified curved isolators are carefully studied by simulation. The results show the shock-train behavior is subject to complex pressure field created duct deflection, eventually presenting five modes during a backpressure-varying process. Of them, most special one abrupt leap. It appears as leading shocks interact with an adverse gradient and follows different path after reversal of direction backpressure takes, which causes hysteresis. If curvature increases,...

Inlet unstart is detrimental to hypersonic airbreathing flights. By unstart, we mean the separation-induced collapse of a supersonic duct flow. The characteristics two-dimensional contraction with an expansion corner are numerically investigated develop universal prediction method and determine mechanism. boundaries under varying angles, entrance heights, Reynolds numbers obtained by translating cowl plate. A self-similar empirical equation boundary that unifies multiple variables proposed...

Accurate calculation of canopy aerodynamic parameters is a prerequisite for precise modeling parafoil airdrop system. This investigation analyses the performance in testing combining leading-edge incision and trailing-edge deflection. Aerodynamic are obtained using computational fluid dynamic simulations, then, output data used to estimate deflection factors. The estimated lift drag coefficients instead traditional based on lifting-line theory incorporated into eight degrees freedom model an...

In this article, the proposed method first evaluates effects on aerodynamic force caused by flight velocity and angular of parafoil delivery system performs an active disturbance rejection control in horizontal direction. Moreover, a glide-ratio controller is designed based characteristics symmetrical flap deflection. For resisting its disturbance, feedforward compensation unit with controller. The performance effectively validated through hardware-in-the-loop simulation.

For autonomous unmanned powered parafoil, the ability to perform a final flare manoeuvre against wind direction can allow considerable reduction of horizontal and vertical velocities at impact, enabling soft landing for safe delivery sensible loads; lack knowledge about surface-layer winds will result in messing up terminal manoeuvre. Moreover, unknown or erroneous also prevent parafoil system from reaching target area. To realize accurate trajectory tracking environment, an efficient...

This paper mainly studied the exponential stability of singular switched systems with impulse effect. Without lose generality, supposed that there are stable and unstable subsystems in systems. Combining multi-Lyapunov function mode-dependent average dwell time method, some sufficient conditions for impulsive effect obtained. Then two kinds controllers designed to ensure each subsystem eliminate when switch occurs according given conditions.

Accurate lateral trajectory tracking control of powered parafoil system with high capacity resisting wind disturbance still remains a challenging problem. To reduce the influence variable on yaw angle parafoil, novel approach combining compensation active rejection (ADRC) is proposed. The dynamic feedforward controller and ADRC are respectively designed. can be directly compensated in process, such that precision disturbance-rejection enhanced simultaneously. Mathematical simulations show...

For the accurate altitude control of powered parafoil system, a novel modelling method and methodology are designed in this paper. Firstly, based on computational fluid dynamics, proposed model can accurately simulate actual flight state system. Then, double closed-loop controller active disturbance rejection is designed. With methodology, precise be realised. By analysing theory control, will stable valid. At last, after detailed verification hardware-in-the-loop simulations, experiment...

The present paper focuses on the Lagrange optimization of shock waves for a two-dimensional hypersonic inlet by limiting cowl internal angle and length. results indicate significant influences geometric constraints configuration performances an inlet. Specifically, mainly affects compression section; length both external sections where intensity shows deviation equal. In addition, optimized inlets at off-design points are further numerically simulated. A prominent discovery is that longer...

A high precision and novel modeling method, to identify the aerodynamic parameters of parafoil based on CFD(Computational Fluid Dynamics) is proposed. By solving governing equations k — ε equations, effects leading edge incision performance stability are investigated. It concluded that increasing length slope can decrease lift coefficient increase drag coefficient, stall angle attack ratio also decreased. The have different parafoil. Increasing affects pressure distribution upper lower wing...

The calculation of canopy aerodynamic parameters plays an important part in the airdrop system. Based on finite volume method, this paper calculates parafoil systems, and then deflection incision factors are estimated by CFD output data. obtained lift drag coefficients instead traditional based lifting-line theory incorporated into equation a active disturbance rejection control strategy is applied to systems. effectiveness proposed method can be demonstrated simulation results. work may...