Cargo Airdrop Research Articles

Landing Reliability Assessment of Airdrop System Based on Vine-Bayesian Network

The landing phase of an airdrop process is prone to accidents, and thus, it is important to assess the landing reliability for an airdrop system. However, full field tests to assess the reliability are unacceptable due to their cost and the time required. As such, it is necessary to estimate the reliability in the design stage. To address this problem, a method based on vine-Bayesian Network (vine-BN) is proposed to assess the landing reliability by fusing multisource information. First, the network structure is determined by the relationship between data of simulation or ground tests and failure modes. Then, nodes are defined as random variables on [0, 1] based on the definition of the performance metric. Finally, the dependence between nodes is quantified by expert opinions. To illustrate the effectiveness of the method, a particular ground test or simulation is chosen to establish a network for a typical heavy cargo airdrop system (HCADS). Forward and backward propagation is carried out on the network. The forward analysis predicts the landing reliability in the design stage through multisource information fusion. Beta distribution is applied to fit the fusion result, so Bayesian inference is made to perform field test times decision-making. The backward analysis works to identify the key performance metrics related to landing reliability. The results and analysis manifest that vine-BN is feasible for fusing multisource information. Through the network, the reliability of the current design can be predicted effectively, and the field test times can be remarkably reduced. This method plays a crucial role in airdrop system design and reducing test time and labor.

Adaptive mutant particle swarm optimization based precise cargo airdrop of unmanned aerial vehicles

Emerging unmanned system technologies and smart logistics have motivated logistics enterprises to use unmanned aerial vehicles (UAVs) for last-mile cargo delivery through the air so as to benefit from its flexibility and low cost. It is useful to deliver cargoes by airdrops from fixed-wing UAVs. However, wind and parameter errors of the UAV could make the cargo deviate from the desired landing point. To improve the accuracy of airdrop methods, this paper presents the Continuously Computed Release Point under conditions of strong wind (SW-CCRP) airdrop strategy to transport the cargo to a given position by a fixed-wing UAV. In this strategy, a set of differential equations are used to model the cargo motion and wind perturbations are considered. Based on the established motion model and the kinematic relationships between the cargo and the target position, the expected release point can be accurately predicted in real time. In order to satisfy the precision requirement, the precision assignment is studied to determine the permissible parameter error ranges. In view of that the conventional precision assignment methods are difficult to be applied in the airdrop system because of its complexity and strong nonlinearity, an adaptive mutant particle swarm optimization (AMPSO) algorithm is proposed to solve this problem, in which the adaptive inertia weight can balance the global and local search. In addition, the mutation factor of the AMPSO is able to avoid premature convergence and stagnation. Finally, two specific test scenarios are designed to validate the effectiveness of the proposed approaches.

Modeling and Analysis of a Generic Internal Cargo Airdrop System for a Tandem Helicopter

This article describes the results of modeling and analysis of a generic internal cargo system using a discretization method of the vector mechanics. The model can be easily incorporated into a tandem helicopter model and is intended for use of simulation and investigating the problems of flight dynamics, control, etc., both in flight operation loading a cargo and flight operation in the process of airdrops. The model is derived by considering the main descriptions of the cargo, including the linear and rotational dynamics, the kinematics, and the forces and moments acting on the helicopter. A simulation method embedded with a numerical trim algorithm is developed for the complete coupling helicopter/cargo nonlinear dynamics system. The simulation application of the model is illustrated, including the case of flight operation loading a cargo by considering three mass configurations of 3000, 4500, and 6000 kg, and the case of flight operation in the process of airdrops at velocities of 0, 40, 80, 120, and 160 knots. Stabilities of the helicopter in the process of airdrops are also analyzed. The major conclusions drawn are: (i) the tandem helicopter has a good attitude maintaining ability in the whole flight velocity envelope when it conducts a flight operation loading a cargo; (ii) in the process of airdrops, the increase in flight velocity will constantly decrease the helicopter pitching attitude and increases the total airdrop time and decreases the backward moving velocity of the cargo, and helicopter flying at a velocity between 80 and 120 knots might be acceptable; (iii) the stabilities of both the longitudinal and lateral periodic modes are continuing to decrease during the backward movement of the cargo.

Аналіз досвіду проведення заходів з десантування вантажів парашутним способом в антитерористичній операції

Пріоритетним способом доставки органів розвідки в тил противника та підтримання (забезпечення) їхніх подальших дій є парашутне десантування. Останнім часом цей напрям стрімко розвивається в провідних країнах світу та набуває широкого застосування під час проведення спеціальних і загальновійськових операцій у локальних конфліктах. З огляду на це важливим є поглиблений аналіз власного досвіду та оцінювання наявних сил та засобів доставки повітряних десантів. Стаття містить загальний опис проблем, виявлених у процесі виконання практичних завдань з десантування вантажів під час ведення бойових дій на сході України. За результатами проведеного аналізу запропоновані шляхи вирішення висвітлених проблемних питань, надані пропозиції до проектів керівних документів, методичних рекомендацій. Висвітлені нові перспективні способи застосування повітрянодесантної техніки, що може сприяти підвищенню ефективності застосування повітряного десантування розвідувальних органів.

Development of a Cargo Airdrop Modeling Method for a Tactical Blended-Wing-Body UAV

In this paper, the development of a cargo airdrop modeling method is presented for a fixed-wing tactical UAV. The UAV, which is being developed in the framework of the DELAER UAS project, is based on the Blended-Wing-Body layout, and its mission is to deliver cargo and lifesaving supplies via airdrop, to remote and isolated Greek territories as well as over isolated islands in the Aegean Sea. At first, a simplified kinematic model is developed, to describe the trajectory of the cargo. Then, the critical airdrop parameters, such as the aerodynamic drag and the effect of wind gusts, are identified and incorporated to the model. Based on this model, an analysis methodology is proposed, conducted in several simulation loops. In each simulation loop, the cargo mass, release height, drop velocity and wind gust speed are the main variables. The results are given in a form of scatter plots, depicting the simulated cargo airdrop positions on the ground (or sea), around an actual target location, with respect to the drop height, drop velocity and wing magnitude. A solid conclusion is that, by releasing the cargo box with tailwind, the accuracy of the airdrop can be improved as much as 67% compared to any other wind direction.

An image measurement technique for trajectory and attitude of cargo airdrop

An image measurement technique for trajectory and attitude of cargo airdrop

An image measurement technique for trajectory and attitude of cargo airdrop

An image measurement technique for trajectory and attitude of cargo airdrop

Optimal Design of Airbag Landing System without Rebound

Airbag system has so many advantages including small volume, superior cushioning performance and easy to control that it has been widely used in many fields such as heavy cargo airdrop, soft landing of spacecraft and so on. In this paper, an optimal design method of the airbag is proposed. First, based on the law of thermodynamics and the deformation assumption of airbag, a mathematical model of airbag landing process is established. The results of the model calculation of the cylindrical airbag is preferably consistent with the results of finite element analysis, which shows that the airbag mathematical model is reasonable and accurate. Second, on the basis of this model, the optimal design method of the airbag without rebound is proposed to solve the problem of rebound which will result in uncontrollable attitude and secondary shock in the landing processes. In this method, the evaluation index of airbag cushioning performance is determined, then the key design parameters which have significant impact on airbag cushioning performance are studied, and the optimization model of airbag under constraint with no rebound is subsequently established and solved. Third, by this method, a cylindrical airbag without rebound is obtained. Compared with the non-optimized one, the maximum impact acceleration of the optimized cylindrical airbag is smaller. Consequently, the effectiveness of the proposed optimal design method is verified.

Development of an efficient contact-friction model for high-fidelity cargo airdrop simulation

High-fidelity cargo airdrop simulation requires the contact dynamics between an aircraft and a cargo to be modeled accurately. This paper presents a general and efficient contact-friction model for simulation of aircraft-cargo coupling dynamics during airdrops. The proposed approach has the same essence as that of the finite element node-to-segment contact formulation, which leads to a flexible, straight forward, and efficient code implementation. The formulation is developed under an arbitrary moving frame with both the aircraft and the cargo being treated as general six-degree-of-freedom rigid bodies, and thus it eliminates the restrictions of lateral symmetric assumptions in most existing methods. Moreover, the aircraft-cargo coupling algorithm is discussed in detail, and some practical implementation details are presented. The accuracy and capability of the present method are demonstrated through three numerical examples with increasing complexity and fidelity.

Dynamic model for internally carried air-launched rocket

For rigid-flexible coupling multi-body with variable topology, such as the system of internally carried air-launched or heavy cargo airdrop, in order to construct a dynamic model with unified form, avoid redundancy in the modeling process and make the solution independent, a method based on the equivalent rigidization model was proposed. It divides a system into independent subsystems by cutting off the joints, of which types are changed with the operation process of the system. And models of different subsystems can be constructed via selecting suitable modeling methods. Subsystem models with flexible bodies are on the basis of the equivalent rigidization model which replaces the flexible bodies with the virtual rigid bodies. And the solution for sanction, which is based on the constraints force algorithm (CFA) and vector mechanics, can be independent on the state equations. The internally carried air-launched system was taken as an example for verifying validity and feasibility of the method and theory. The dynamic model of aircraft-rocket-parachute system in the entire phase was constructed. Comparing the modeling method with the others, the modeling process was programmed; and form of the model is unified and simple. The model, method and theory can be used to analyze other similar systems such as heavy cargo airdrop system and capsule parachute recovery system.

An Efficient Contact Model for the Simulation of Cargo Airdrop Extraction Phase

A high-fidelity cargo airdrop simulation requires the accurate modeling of the contact dynamics between an aircraft and its cargo. This paper presents a general and efficient contact-friction model for the simulation of aircraft-cargo coupling dynamics during an airdrop extraction phase. The proposed approach has the same essence as the finite element node-to-segment contact formulation, which leads to a flexible, straightforward, and efficient code implementation. The formulation is developed under an arbitrary moving frame with both aircraft and cargo treated as general six degrees-of-freedom rigid bodies, thus eliminating the restrictions of lateral symmetric assumptions in most existing methods. Moreover, the aircraft-cargo coupling algorithm is discussed in detail, and some practical implementation details are presented. The accuracy and capability of the present method are demonstrated through four numerical examples with increasing complexity and fidelity.

Active disturbance rejection control for heavy cargo airdrop operations

In view of the strong nonlinear and coupling characteristics of the airdrop operations, a novel control method is proposed based on the active disturbance rejection control (ADRC) for decoupling control strategy of the pitch angle and airspeed. The unknown disturbances, including aerodynamic uncertainty and nonlinear coupling effect between the aircraft and cargo dynamics, are estimated and compensated with the extended state observer (ESO). Meanwhile, the nonlinear law state error feedback (NLSEF) is adopted to restrain the compensation residual. Simulation and flight quality evaluation shows the satisfactory capacity and strong robustness of the proposed control method in guaranteeing the airdrop task and flight safety.

Modeling and control for ultra-low altitude cargo airdrop

PurposeThe purpose of this paper is to model the aircraft-cargo’s coupling dynamics during ultra-low altitude heavy cargo airdrop and to design the aircraft’s robust flight control law counteracting its aerodynamic coefficients perturbation induced by ground effect and the disturbance from the sliding cargo inside.Design/methodology/approachAircraft-cargo system coupling dynamics model in vertical plane is derived using the Kane method. Trimmed point is calculated when the cargo fixed in the cabin and then the approximate linearized motion equation of the aircraft upon it is derived. The robust stability and robust H∞ optimal disturbance restraint flight control law are designed countering the aircraft’s aerodynamic coefficients perturbation and the disturbance moment, respectively.FindingsNumerical simulation shows the effectiveness of the proposed control law with elevator deflection as a unique control input.Practical implicationsThe model derived and control law designed in the paper can be applied to heavy cargo airdrop integrated design and relevant parameters choice.Originality/valueThe dynamics model derived is closed, namely, the model can be called in numerical simulation free of assuming the values of parachute’s extraction force or cargo’s relative sliding acceleration or velocity as seen in many literatures. The modeling is simplified using Kane method rather than Newton’s laws. The robust control law proposed is effective in guaranteeing the aircraft’s flight stability and disturbance restraint performance in the presence of aerodynamic coefficients perturbation.

Numerical Simulation of Wake Flowfield Behind the C-130 with Cargo Ramp Open

Simulation results are presented for a C-130 aircraft configured to perform cargo airdrop operations. Flight operations with the cargo ramp open lead to strong vortical flow structures and unsteady flows, which can adversely affect airdrop operations and parachute deployments. The results document complex wake structures formed behind the C-130 with the cargo ramp open at 0 and 50% flap settings. In particular, the wake contains two asymmetric counter-rotating vortices formed between the open ramp and the upsweep section of the aircraft and near the rear edges of the ramp. The flow separates along these edges because of the sharp turn that flow makes as it enters the cargo compartment. The separated flow then rolls up into two vortices. These vortices move outward and upward, and then they pass very near the lower surface of the horizontal stabilizer. These vortical flows lead to unsteady airloads on the horizontal stabilizer, and thus the aircraft. The wake effects are larger behind the upper upsweep section and are minimum at the lower positions. Grid and time sensitivity studies are performed for several geometries to ensure numerical simulations are accurate for the separated and vortical flows. The results show that, as the grid becomes more refined in the region behind the upsweep section of the aircraft, the localized wake structures and unsteady effects are better captured by the flow solver.

Modeling and active disturbance rejection control for sequential airdrop operations

With the assumption t at the motion acceleration of the cargo is unknown, the dynamic model that accords with the engineering practice of sequential cargo airdrop operations is derived by using the separation body method, which can describe the impact of the sequential moving cargos on the flight safety and airdrop-mission capacity. On this basis, a novel flight control method is designed based on the active disturbance rejection control (ADRC) theory. the system is decoupled and linearized through the nonlinear state error feedback; the total unknown disturbances, including unmolded dynamics and uncertainty, are estimated and compensated real-timely by the extended state observer. Moreover, with the consideration of the time-delay system, the ADRC is improved to enhance the accuracy and rapidity of the control system. Simulations are carried out under the condition that one transport aircraft performs sequential airdrop operations. The results verify that the desirable performance and robustness have been achieved and the proposed control method is quite competent for the sequential airdrop operations.

Adaptive backstepping sliding mode control for heavy-weight airdrop operations

This paper proposes an adaptive backstepping sliding mode flight control method that is compatible with heavyweight cargo airdrop. The goal is to maintain the plane states during cargo extraction process, in the presence of uncertainties of both constant and time-varying types, as well as matched and unmatched types. A backstepping sliding mode flight control law with parameter adaptation is presented based on the plane-cargo dynamics in strict-feedback form. The control approach consists in having an adaptation law that approximates the disturbance and uncertain aerodynamic function, which is separated from the complex nonlinearities. Also, the adaptation algorithm with projection can bound the estimated function. This ensures the robustness of the controller against time-varying disturbance and uncertainty. The convergence performance and robustness property of the control law are proved by the Lyapunov theory. The control effect is evaluated on a transport plane performing a maximum load airdrop task in a number of simulation scenarios.

Disturbance Observer-Based Dynamic Surface Control of Transport Aircraft With Continuous Heavy Cargo Airdrop

This paper investigates the dynamic surface control of nonlinear transport aircraft model during the process of continuous heavy cargo airdrop in case of disturbance and actuator saturation. For the continuous airdrop process, the effects of moving process parameters include cargo mass and moving items upon the flight and the aircraft dynamics is with dramatic change. The dynamic surface related technique is designed for the attitude subsystem with unmatched disturbance and unknown dynamics so that in each step the virtual control is carefully considered using disturbance observer while the auxiliary signal is constructed in case of actuator saturation. The closed-loop stability is established via Lyapunov approach. In simulation test, it is interesting to find out that continuous airdrop process will deteriorate the system stability if additional control effort is not exerted. The proposed disturbance observer-based control can effectively enhance the reliability and robustness of the system, and can make sure of the smooth system performance at the instant of the heavy cargo separating from the aircraft.

Flight controller design for aircraft low altitude airdrop

Purpose During low altitude airdrop operations, the heavy cargo moving inside and the sudden dropping out exert serious threats on the aircraft safety and mission performance. This paper aims to propose an efficient flight control method for the airdrop operations. Design/methodology/approach A novel controller which combines feedback linearization with nonlinear integral sliding mode control is proposed. The aircraft airdrop model is decoupled and linearized by using the feedback linearization technique. On this basis, an integral sliding mode controller is designed to stabilize the speed and pitch attitude of the aircraft. In the sliding manifold, one class of nonlinear functions with the property of “smaller errors correspond to bigger gains and bigger errors correspond to saturated gains” is introduced to form the integral term; thus, the overcompensation of the integral term to big errors is omitted, and the dynamic response performance is improved. Lyapunov-based stability analysis shows that the controller could completely reject model uncertainties by choosing proper controller parameters. Findings The flight control system with strong robustness could meet the low altitude airdrop indexes in the maximum weight cargo airdrop task. Originality/value This paper fulfils an urgent need to study how to control the aircraft to guarantee mission performance and flight safety during the low altitude airdrop operations.

Kinetic Characteristics Analysis of Aircraft During Heavy Cargo Airdrop

Airdrop is the most important approach for crisis transaction and unexpected events, it is necessary to investigate the flight characteristics of transport aircraft during the dropping process. This paper mainly focuses on the stability, controllability and model simplification of large aircraft with heavy cargo airdrop. In this process, the primary elements which have impact on force and moment are studied theoretically, the role of cargo mass, moving parameters and other factors on dynamical characteristics have been assessed by simulation and analysis. And then the aircraft model simplification is completed for control system designing in future. All the work above shows that the parameters of cargo moving play a dominant role in flight characteristics and the flight equations can be simplified to reduce the design complexity.

Sliding mode disturbance observer-based backstepping control for a transport aircraft

This paper presents a novel control method by integrating the sliding mode disturbance observer-based control and the backstepping control technique, and successfully applies it to a flight control system for heavy cargo airdrop operations. The super-twisting second order sliding mode disturbance observer (SOSMDO) is employed to estimate bounded but otherwise arbitrary disturbances, thus ensuring asymptotic convergence of the estimation error to zero in a finite time. Besides, the integrated controller can significantly improve the robustness of the flight control system to modeling uncertainty and external disturbance in the presence of state/control constraints. The closed-loop stability is guaranteed in the sense of Lyapunov. In addition, the proposed approach can considerably reduce design cycles. The performance of the proposed control method is demonstrated in a very low altitude extraction airdrop simulation with a high-fidelity six-degree-of-freedom transport aircraft model.