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

An integrated method for the implementation of constrained entry control allocation for a reusable launch vehicle is presented. Given any feasible torque commands and control vector constraints, the method can generate control commands to each individual effectors including aerosurfaces and reaction control system (RCS) jets with a desired objective, featuring active set theory, optimal extremum method, and daisy-chained method, which satisfies all the control vector constraints and meets the requirement with high precision and onboard calculation ability. Afterwards, by utilizing unique features of effector failure status parameter, establishing the vehicle health monitor, and generating the reconfigurable control action according to hierarchical message processing technique, the method enables the control allocation system to compensate for inaccuracies and provide reliable and solid performance in the presence of effector failures/degradations. To compare with various control allocation algorithms, onboard reconfigurable control allocations and simulations for a reusable launch vehicle model with effector failures/degradations are presented to demonstrate the capacity and efficiency of this method.

Robust adaptive integral backstepping control for opto-electronic tracking system based on modified LuGre friction model

Adaptive output feedback attitude control for reusable launch vehicle with input constraints and actuator faults

This paper presents a novel algorithm for the design and analysis of an adaptive backstepping controller (ABC) for a microgyroscope. Firstly, Lagrange–Maxwell electromechanical equations are established to derive the dynamic model of a z-axis microgyroscope. Secondly, a nonlinear controller as a backstepping design approach is introduced and deployed in order to drive the trajectory tracking errors to converge to zero with asymptotic stability. Meanwhile, an adaptive estimator is developed and implemented with the backstepping controller to update the value of the parameter estimates in the Lyapunov framework in real-time. In addition, the unknown system parameters including the angular velocity may be estimated online if the persistent excitation (PE) requirement is met. A robust compensator is incorporated in the adaptive backstepping algorithm to suppress the parameter variations and external disturbances. Finally, simulation studies are conducted to prove the validity of the proposed ABC scheme with guaranteed asymptotic stability and excellent tracking performance, as well as consistent parameter estimates in the presence of model uncertainties and disturbances.

In this paper, the problem of integrated guidance and control design is presented with input constraints. Adaptive backstepping is developed for the integrated model in the form of cascade structure with uncertainties. An auxiliary system is adopted to handle the effect of input saturation. First-order filters are introduced to avoid the tedious analytic computations in the design procedure and command filter is exploited to implement the physical constraints on the actuators. All signals in the closed-loop system are proved uniformly ultimate bounded via Lyapunov stability analysis. Simulation results demonstrate the effectiveness of the proposed control strategy.

A nonlinear robust adaptive backstepping attitude controller is designed for a reusable launch vehicle in reentry phase under input constraint, model uncertainty and external disturbance. for the couplings between the translational and rotational motions, a control-oriented model (COM) with uncertainty is firstly derived to succinctly design controller. It is worth pointing out that the uncertain terms in the COM do not need to satisfy linear parameterization assumption, and their upper bounds do not need to be known in advance. The robust adaptive laws are developed to estimate the upper bounds online. To facilitate analytic computation for the time derivative of virtual control input, a second-order filter is employed to estimate it. An additional system is constructed to handle input constraint. By rigorous analysis, the tracking error is guaranteed to converge to a random neighborhood around zero by appropriately choosing parameters. At the end, the effectiveness of the designed controller is shown by compared simulations.

The control problem of a flexible hypersonic vehicle is presented, where input saturation and aerodynamic uncertainty are considered. A control-oriented model including aerodynamic uncertainty is derived for simple controller design due to the nonlinearity and complexity of hypersonic vehicle model. Then it is separated into velocity subsystem and altitude subsystem. On the basis of the integration of robust adaptive control and backstepping technique, respective controller is designed for each subsystem, where an auxiliary signal provided by an additional dynamic system is used to compensate for the control saturation effect. Then to deal with the “explosion of terms” problem inherent in backstepping control, a novel first-order filter is proposed. Simulation results are included to demonstrate the effectiveness of the adaptive backstepping control scheme.

The controller design for reusable launch vehicles is challenging due to enormous amounts of model parameter uncertainties and atmospheric disturbances. This paper first derives six-degree-of-freedom model of a reusable launch vehicle with atmospheric disturbances. Next, four kinds of atmospheric disturbances are introduced and wind models are established respectively. For attitude control of the reusable launch vehicle, a nonsingular terminal sliding mode controller is designed with stability guaranteed. Finally, simulation results show a satisfactory performance for the attitude tracking of the reusable launch vehicle with atmospheric disturbances.

The reusable launch vehicle (RLV) has strongly nonlinear, fast time-varying characters and multiple control modes, which challenge attitude control in task-adaptability greatly. A nonlinear RCS/aerosurfaces compound controller control scheme was presented. First a RLV model equipped with reaction control system (RCS) and aerosurfaces is developed. Then fast and slow loops control system is designed based on time-scale separate theory. The optimal control law was implemented to generate optimal control moments. The control allocation maps the control moment commands into thrusters and aerodynamic effectors' commands. The daisy-chain combination method is applied to the control allocation to deal with the harmonization problem of the RCS and aerosufaces. The Results show the compound control scheme meets the attitude tracking performance requirements. Simulation demonstrates that the nonlinear RCS/aerosurfaces compound controller saves RCS fuel effectively and achieves coordinated control between RCS and aerosurfaces. The control scheme can also be used in other reentry vehicles or aerospace planes.

In this paper, a control simulation of the autonomous landing process of a Vertical Take-Off and Landing (VTVL) Reusable Launch Vehicle (RLV) is proposed and we consider the effects of the inner liquid propellant sloshing, elastic vibration, disturbance force, disturbance torque and other complex conditions in the virtual RLV model. On the basis of dynamics modeling of the RLV, we analyzed RLV's landing process. The landing control system was designed under certain conditions. Co-simulation Research was achieved by ADAMS and MATLAB/Simulink. The simulation results show that the control system performs well.

In this paper, a nonlinear adaptive speed controller for permanent magnet linear synchronous motors based on a newly developed adaptive recursive Backstepping control approach for a permanent magnet synchronous motor drive is discussed and analyzed. The Backstepping technique provides a systematic method to address this type of problem. It combines the notion of Lyapunov function and a controller procedure recursively. The adaptive Backstepping control approach is utilized to obtain the robustness for mismatched parameter uncertainties. The overall stability of the system is shown using Lyapunov stability theorem. The simulation results clearly show that the proposed scheme can track the speed reference.

The control performance of quadrotor unmanned aerial vehicles (UAVs) in complex environments can be affected by external disturbances and other factors. In this paper, an adaptive neural network backstepping controller based on the barrier Lyapunov function (BLF) is designed for a quadrotor UAV with internal uncertainties, input–output constraints and external disturbances. Radial basis function neural networks are used to approximate the uncertainties in the dynamic model of the UAV, while the minimum parameter learning method is combined to accelerate the adjustment speed of neural network weights. A robust term is designed to balance the total system disturbance and improve the anti-interference performance. The BLF is used to handle the output constraint so that the constrained parameters cannot break the predefined constraints. An auxiliary system is introduced to solve input saturation and avoid the dependence of tracking error on the input amplitude in the method of approximating input saturation using the smoothing function. The stability of the control system is demonstrated by the Lyapunov method. The simulation results show that the proposed method has high tracking accuracy compared with the backstepping dynamic surface control method, and the input and output are in the predefined range.

Auxiliary-system-based composite adaptive optimal backstepping control for uncertain nonlinear guidance systems with input constraints

In this paper, we present a nonlinear adaptive backstepping with extended state observer (ESO) trajectory tracking controller for a quadrotor unmanned aerial vehicle (UAV) subject to the multiple disturbances, which include the parametric uncertainties, actuator faults and external disturbance. First, a six-degrees of freedom quadrotor UAV model with the multiple disturbances function is built. Second, the adaptive backstepping controller is designed to track the desired trajectory command aim at internal disturbance. And the adaptive backstepping controller with ESO is designed to track the desired trajectory command aim at external disturbance. Third, the stability of the system is proved by the circle criterion. Finally, under different flight scenarios, simulation results are given to demonstrate the effectiveness of the proposed method.

The berthing of maritime autonomous surface ships (MASSs) is a challenging operation even for an experienced captain due to the required complicated maneuvering at low speeds in a constrained water space. This article addresses safety-aware automatic berthing of MASSs moving in a constrained water region with stationary and moving obstacles. A safety-critical constrained anti-disturbance control method is proposed for the automatic berthing of MASSs subject to velocity constraints, input constraints, and collision-avoidance constraints, as well as ocean disturbances. At the kinematic level, desired linear velocities and yaw rate are prescribed by incorporating a line-of-sight guidance scheme to achieve position-heading stabilization. At the kinetic level, an anti-disturbance kinetic control law is designed based on an extended state observer. Through converting the input constraints to velocity constraints on guidance signals, the safety-guidance signals are obtained by solving a quadratic programming problem subject to the state, input, and collision-avoidance constraints. It is proven that an MASS controlled by using the proposed method is input-to-state safe in the presence of ocean disturbances. Simulation results are elaborated to substantiate the efficacy of the proposed safety-certified control law for the automatic berthing of an MASS subject to physical constraints and environmental disturbances.