Reusable Launch Vehicle Model Research Articles

Fractional-order sliding mode control with a predefined-time observer for VTVL reusable launch vehicles under actuator faults and saturation constraints

For vertical takeoff vertical landing (VTVL) reusable launch vehicle (RLV) with actuator faults and saturation constraints, this paper presents a composite control system including a high-order predefined-time extended state observer (HO-PTESO), a predefined-time anti-saturation compensator (PTASC), and a fractional-order practical predefined-time sliding mode control law (FO-PPTSMC). The HO-PTESO accomplishes the precise estimation of disturbance in a time interval predefined by only one design parameter, resulting in a simple and weakly conservative parameter tuning process for temporal demands. Moreover, the peaking value problem is well addressed. The PTASC serves to ensure the stability of the saturated system. Auxiliary variables of the PTASC remain bounded during the saturation process and vanish within the predefined time interval after the saturation process ends, avoiding long-term impacts on the attitude tracking that are common concerns for existing ASCs. Using the estimated disturbance, the FO-PPTSMC enforces unsaturated system states to a predefined residual set of the origin in a chattering-alleviated manner within the predefined time interval. Two parameters respectively predefine the convergence range and time, resulting in a considerably simplified synthesis procedure. Ultimately, numerical simulations on the double integrator system and VTVL RLV model validate the efficiency of the proposed control system.

Aerodynamic interactions of a Reusable Launch Vehicle model with different nose configurations

The Two-Stage-To-Orbit (TSTO) hypersonic vehicle is an example of a Reusable Launch Vehicle (RLVs) configuration, and it has the advantages of small mass and large payload. A TSTO concept aircraft comprising a booster and a cruiser was proposed in this paper. The typical trapezoidal wing configuration was used as the booster and the wing spherical cone was used as the cruiser. Based on the three-dimensional hybrid LES/RANS numerical simulation method, the aerodynamic interference characteristics of different nose configurations in the cruise stage were studied, the pressure and heat flux distributions on the upper and lower surfaces of the cruise stage and the booster stage were calculated and analysed, the characteristics and mechanism of the aerodynamic interference between the two stages were revealed, and the structural changes of the flow field and the characteristics of the aerodynamic interference under different head configurations of the cruise stage were compared. The results show that the shock/shock interaction outside the blunt nose of the cruiser causes serious aerodynamic and thermal problems on the stagnation point. There are complex shock wave/boundary layer interactions and reflected shock trains between the two stages, which results in high-level pressure and heat flux on the surfaces. An alteration of the nose configuration can greatly improve the wall pressure and heat flux on the surface. The Bend cone model provides the greatest reduction in peak pressure and heat flux and is a suitable choice for an RLV cruiser.

Finite-Time Super-Twisting Controller Based on SESO Design for RLV Re-Entry Phase

In this paper, an improved extended state observer (ESO) based on sigmoid function and a finite-time convergence attitude controller are designed for reusable launch vehicle (RLV) in the re-entry phase. First, a control-oriented model (COM) of the RLV is established. According to the singular perturbation theory, the RLV control system is divided into an outer-loop and inner-loop subsystems. Second, a sigmoid function ESO (SESO) is proposed to estimate the model uncertainties and external disturbance caused by the large attitude maneuver and complicated external environment during the RLV re-entry phase. The continuous differentiable sigmoid function has the significant ability in noise suppression. By selecting the proper Lyapunov function, the stability of the SESO is proved. Then, based on the sliding mode control (SMC) theory, an improved multivariable super-twisting high-order sliding mode controller is designed. The finite-time convergence for the whole system is proven by the Lyapunov function technology. Finally, a 6-degree-of-freedom (6-DOF) RLV model is utilized to simulate to verify the effectiveness and robustness of the proposed control scheme.

Robust adaptive constrained backstepping flight controller design for re-entry reusable launch vehicle under input constraint

A nonlinear constrained controller is designed for a reusable launch vehicle during re-entry phase in the presence of model uncertainty, external disturbance, and input constraint, via combining sliding mode control and adaptive backstepping control. Since the complex coupling between the translational and rotational dynamics of reusable launch vehicle, a control-oriented model derived from rotational dynamic is used for controller design. During the virtual control input design procedure, a dynamic robust term is utilized to compensate for the uncertainty. In addition, a filter is applied to handle “explosion of terms” problem during the actual control input design. To reduce the computational burden, adaptive law is used to evaluate the unknown norm bound of the lumped uncertainty. An auxiliary system is constructed to compensate for the input constraint effect. The stability of the closed-loop system is analyzed based on Lyapunov theory. Simulation results demonstrate the validity of the developed controller in providing stable tracking of the guidance command by numerical simulation on the 6-degree-of-freedom model of reusable launch vehicle.

Evolution of attitude control law of an Indian re-entry launch vehicle

Reusable launch vehicle (RLV) is a goal pursued by different aerospace agencies, world-wide. Indian space research organization is also one among them. This paper covers the challenges faced and the solutions developed for control law design of a typical re-entry vehicle. The first stage of the test vehicle, used for technology demonstration mission, is a conventional solid rocket motor. The second stage of the test vehicle is a winged body vehicle termed as technology demonstrator vehicle (TDV). This TDV forms the orbiter stage of a conceptual two-stage-to-orbit vehicle. While developing control law for TDV, the experience gained in developing control law for expendable launch vehicles is fully utilized. Due to the presence of winged-second-stage, the solution for attitude control problem naturally inherits the procedure and technology used for designing control law of an aircraft. There are significant differences a re-entry vehicle has in comparison to both aircraft and launch vehicles. Due to these differences, the final control law depends on both aircraft and launch vehicle control law design methodologies. In this paper the authors share the insights gained in control law design of a RLV. The paper gives the reasons for the selection of a combination of co-ordinate systems, for the development of linear plant model of RLV. It emphasizes the difference in the plant modelling with respect to aircraft dynamics in accounting gravitational force in the linear plant model. Requirement of pseudo trim condition for force balance is described in the paper. The paper highlights the commands to be tracked and variables to be fed back during different regimes of re-entry flight. Issues in control law gain design with respect to selected sensors and their placement are elaborated in the paper. Insights on the aspect of trim scheduling, gain scheduling, and finalization of control law structure are also given in the paper.

Adaptive Backstepping Finite Time Attitude Control of Reentry RLV with Input Constraint

This paper presents the finite time attitude tracking control problem of reusable launch vehicle (RLV) in reentry phase under input constraint, model uncertainty, and external disturbance. A control-oriented model of rotational dynamics is developed and used for controller design for the complex coupling of the translational and rotational dynamics. Firstly, fast terminal sliding mode control is incorporated into backstepping control to design controller considering model uncertainty and external disturbance. The “explosion of terms” problem inherent in backstepping control is eliminated by a robust second order filter. Secondly, the control problem in the presence of input constraint is further considered, and a constrained adaptive backstepping fast terminal sliding mode control scheme is developed. At the control design level, adaptive law is employed to estimate the unknown norm bound of lumped uncertainty with the reduction of computational burden. The Lyapunov-based stability analysis of the closed-loop system is carried out. The control performance is presented via the simulation of six-degree-of-freedom (6-DOF) model of RLV.

Active fault tolerant control design for reusable launch vehicle using adaptive sliding mode technique

In this paper, the problem of active fault tolerant control for a reusable launch vehicle (RLV) with actuator fault using both adaptive and sliding mode techniques is investigated. Firstly, the kinematic equations and dynamic equations of RLV are given, which represent the characteristics of RLV in reentry flight phase. For the dynamic model of RLV in faulty case, a fault detection scheme is proposed by designing a nonlinear fault detection observer. Then, an active fault tolerant tracking strategy for RLV attitude control systems is presented by making use of both adaptive control and sliding mode control techniques, which can guarantee the asymptotic output tracking of the closed-loop attitude control systems in spite of actuator fault. Finally, simulation results are given to demonstrate the effectiveness of the developed fault tolerant control scheme.

Integrated Entry Guidance for Reusable Launch Vehicle

AbstractA method for the implementation of integrated three-degree-of-freedom constrained entry guidance for reusable launch vehicle is presented. Given any feasible entry conditions, terminal area energy management interface conditions, and the reference trajectory generated onboard then, the method can generate a longitudinal guidance profile rapidly, featuring linear quadratic regular method and a proportional-integral-derivative tracking law with time-varying gains, which satisfies all the entry corridor constraints and meets the requirements with high precision. Afterwards, by utilizing special features of crossrange parameter, establishing bank-reversal corridor, and determining bank-reversals according to dynamically adjusted method, the algorithm enables the lateral entry guidance system to fly a wide range of missions and provides reliable and good performance in the presence of significant aerodynamic modeling uncertainty. Fast trajectory guidance profiles and simulations with a reusable launch vehicle model for various missions and aerodynamic uncertainties are presented to demonstrate the capacity and reliability of this method.

On-board entry trajectory planning for sub-orbital flight

An algorithm for on-board planning of sub-orbital entry trajectories is presented. For entry vehicles with low lift-to-drag ratios and entering entry flight at sub-orbital speeds, this algorithm fills a gap left in a recently developed methodology for on-board generation of three-degree-of-freedom (3DOF) entry trajectories. The algorithm developed in this paper is able to reliably generate a 3DOF feasible sub-orbital entry trajectory in a time frame compatible with on-board environment. The combination of this algorithm and an algorithm recently developed for orbital entry missions provides the capability for full-envelope autonomous adaptive entry guidance. The current algorithm is validated by extensive high fidelity simulations using a sub-orbital reusable launch vehicle model and difficult mission scenarios including failures and aborts.

B302 感圧・感温塗料圧力計測系のための取得画像後処理ソフトウェアの開発

To promote utilization of pressure/temperature sensitive paint (PSP/TSP) surface pressure measurement for wind tunnel testing, a robust and user-friendly post-processing software named Software for Molecular-sensing Application-oriented Postprocessing (SMAP) has been developed andnow it is open to the public on our website. SMAP enables efficient image data processing for PSP/TSP surface pressure measurement with dark calibration, averaging, several smoothing options, manual/automatic marker detection, edge detection, image registration, image division, temperaturecalibration, pressure calibration, and surface pressure mapping to three-dimensional model. In this paper, some features of SMAP are introduced and wind tunnel tests of a reusable launch vehicle model in the large-scale. transonic/supersonic wind tunnel in ISAS/JAXA are demonstrated.

Onboard Generation of Three-Dimensional Constrained Entry Trajectories

A methodology for very fast design of three-degree-of-freedom (3DOF) entry trajectories subject to all common inequality and equality constraints is developed. The approach makes novel use of the quasi-equilibrium glide phenomenon in lifting entry as a centerpiece for effective and efficient enforcement of the inequality constraints. The highly constrained nonlinear trajectory planning problem is decomposed into two sequential one-parameter search problems. The algorithm is able to generate a complete and feasible 3DOF entry trajectory of 25-min flight time in about 2-3 s on a desktop computer, given the entry conditions, values of constraint parameters, and final conditions. High-fidelity numerical simulations with a reusable launch vehicle model for various entry missions and trajectory planning using the space shuttle model are presented to demonstrate the capability and effectiveness of the algorithm.