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This paper investigates a rapid modeling method and robust analysis of hypersonic vehicles using multidisciplinary integrated techniques. First, the geometrical configuration is described using parametric methods based on the class–shape technique. Aerodynamic forces and moments are estimated for the specific configuration using engineering methods. Moreover, the nonlinear model is simplified by the polynomial fitting expressions, and the linear variable parameter model is obtained for the tracking control design and dynamic characteristic analysis with the aid of the sensitivity analysis and gap metric methods. A velocity-driven trajectory design method is deduced for hypersonic ascent, and the tracking control law is developed to realize the flight process from the initial point to the cruise point. Furthermore, a robust analysis process based on gap margin is proposed for climb trajectory tracking. Simulation results are provided to verify the feasibility of the proposed modeling method and show that the flight control of a hypersonic vehicle is more sensitive to altitude variation. [ABSTRACT FROM AUTHOR]

Static stability margin is a critical parameter in flight control design. The feasible range of it must cover the uncertainty through the flight. To reasonably identify the feasible range of static stability margin in advance, an approach based on guardian maps is proposed for flight control of hypersonic flight vehicles with input saturation. First, the model of hypersonic flight vehicle (HFV) is established as a parametric plant. Then, flying quality requirements for the closed-loop system are formulated as inequality constraints using guardian maps. Moreover, by using linear matrix inequality, the saturation of elevators is taken into account in the integrated control of attitude control. The prescribed minimum of static stability margin that ensures the flying quality of hypersonic flight vehicles with input saturation is obtained. Furthermore, from the prospective of integrated control, it is shown that the feasible range of static stability margin can be enlarged by changing aerodynamic characteristics. The effectiveness of the proposed approach is validated by numerical simulation. [ABSTRACT FROM AUTHOR]

Trajectory optimization problem for hypersonic vehicles has long been recognized as a difficult problem. This paper brings control constraints into the trajectory optimization to make the optimal trajectory meet the requirements of control performance. The strong nonlinear characteristic of the ascent phase aerodynamics makes the trajectory optimization problem difficult to be solved by the optimal control theory. A trajectory optimization algorithm based on the improved pigeon-inspired optimization (PIO) algorithm is proposed to solve the complex trajectory optimization problem under multiple constraints. To overcome the obstacle of premature convergence and deceptiveness, the evolutionary strategy of qubit in quantum evolutionary algorithm (QEA) is introduced into the PIO to maintain population diversity and judge the optimal solution. To handle constraints, the penalty function is used to construct the fitness function. The optimal ascent trajectory is obtained by utilizing the improved PIO algorithm. Then, the trajectory inverse algorithm is used to verify the feasibility of the optimal trajectory to ensure that a feasible optimal trajectory is obtained. The comparison results show that the proposed algorithm outperforms particle swarm optimization (PSO) and standard PIO on trajectory optimization. Meanwhile, the simulation result shows that the performance of the optimal ascent trajectory with control constraints is improved and the trajectory is feasible. Therefore, the method is potentially feasible for solving the ascent trajectory optimization problem under control constraint for hypersonic vehicles. [ABSTRACT FROM AUTHOR]

This paper presents a novel control design strategy for the hypersonic vehicle using the elastic surrogate model. First, the parametric model is established for the rigid mode of the hypersonic vehicle based on the engineering estimation and panel methods. Then, the beam surrogate model is applied to identify the elastic mode of the hypersonic vehicle, and the complete parametric model including the rigid and elastic modes is obtained accordingly. Afterward, the control-relevant model is acquired based on the Morris sensitivity analysis method. Furthermore, the control system using the surrogate model is proposed for the hypersonic vehicle to suppress elastic disturbances and maintain system stability. Finally, an illustrative example of the hypersonic vehicle is provided to verify the effectiveness of the presented methods. [ABSTRACT FROM AUTHOR]

Overall design in many air-breathing hypersonic vehicles (AHSVs) uses the integrated airframe/scramjet configuration formed with elongated fuselage and light structure, resulting in intricate aerodynamic–propulsive-elastic couplings. In this paper, a high-fidelity flexible AHSV dynamic modeling procedure is proposed at first, which consists of three main parts: i) panel method based aerodynamic modeling; ii) scramjet modeling; iii) finite-element-method (FEM) based aeroelastic modeling. Unsteady and viscous effects are estimated through linear piston theory and Eckert's reference temperature method, respectively. Additional models for shock interaction, ram-to-scram transition, and finite rate chemistry reaction are also included. To overcome the intractability of physics-based model, the Morris method is applied to identify the main influence factors during surrogate modeling. Then to investigate the flexible mode effect on the stability boundary, the principle of Null-controllability region (NCR) is employed, under control input saturation and bandwidth constraints. The X-43A like air-breathing hypersonic vehicle operating at cruise condition is studied for verification purpose, and the Monte-Carlo simulation results demonstrate the effectiveness of the proposed dynamic modeling and performance limitation analysis approach. [ABSTRACT FROM AUTHOR]

The hypersonic waverider using the morphing configuration can improve the overall performance and broaden the flight range. On the other hand, the hypersonic waverider belongs to the lightweight construction, leading to the presence of the intrinsic elasticity. As a result, the integrated consideration of the active deformation and elastic action is important for the morphing waverider to realize global optimization. In this paper, the contro-integrated design methods are proposed for the morphing waverider to implement the trade-off analysis between the active deformation and intrinsic elasticity. First, the parametric model is built to describe the hypersonic flight characteristics. Then, the elastic dynamics is introduced to quantify the coupling responses associated with the angle of attack and elevon deflection. Furthermore, the integrated design is considered for the active deformation and inherent elastic action, and also the control law is designed to suppress the active and passive morphing disturbances. Finally, the simulation is conducted to test the effectiveness of the presented methods for the morphing waverider. [ABSTRACT FROM AUTHOR]

Waverider hypersonic vehicles have the characteristics of strong coupling between subsystems and the wide range flight envelope. Therefore, the control analysis and synthesis should be integrated into the early stage of vehicle design, the parameters in control system should be optimized as well as the parameters in aerodynamic, propulsion and structure systems in the vehicle design, and the software tool to facilitate the design process should be developed. Firstly, a series of parameters are used to describe the geometric, and a parameterized model of hypersonic vehicles is established. Then, the objective function is determined according to mission requirements, and then optimal parameter set will be obtained by searching variables in design space to satisfy the constraints. Then, the control relaxed specifications, such as controlability, stability, robustness and time-domain performances etc., are set as the optimization indexes, and the proposal on how to adjust parameters is feedbacked to optimization loop. A optimal vehicle configurations is obtained. Finally, the software, which is used to assist vehicle design, is able to carry out vehicle modeling, analyze static and dynamic characteristics, and provide various controller design templates automatically. [ABSTRACT FROM AUTHOR]

Guardian maps provide a concise and practical approach to parametric robustness analysis. However, non-convexity and nonlinearity of high dimensional guardian maps restrict the application. In this paper, a closed-loop performance-oriented approach to parametric robustness analysis is proposed. First, a sufficient condition for the existence of parametric stable region satisfying the closed-loop performance is presented. To further identify the maximum stable region, a robustness criterion is provided, leading to a numerical approach for parametric stability margin. The superiority of the proposed method lies in the applicability to robust performance analysis with nonlinear high-dimensional parameters. Applications are discussed with emphasis on the flight control of hypersonic vehicles, including robust control design and robust stability analysis. Results are of significant that no prior knowledge on controller tuning is required, and parametric stability margin can be obtained automatically regardless of the dimension of parameter space. [ABSTRACT FROM AUTHOR]