Control-oriented modeling and adaptive backstepping control for a nonminimum phase hypersonic vehicle

Phase plane design based fast altitude tracking control for hypersonic flight vehicle with angle of attack constraint

For the longitudinal model of an air-breathing hypersonic vehicle, its pitch dynamics is characterized by nonminimum phase when the term "elevator to lift" is not negligible. Nonminimum-phase characteristic is one of the main challenges for control design. In this paper, the control design problem is investigated for this kind of hypersonic vehicle with uncertain parameters and a novel design philosophy is presented based on analysis of the plant's dynamics. Firstly, this model is separated as velocity subsystem and pitch dynamics subsystem. For the former, an adaptive dynamic inversion controller is derived. For the latter, a high-gain adaptive dynamic surface controller is derived. Furthermore, the stability analysis represents the states and tracking errors are ultimately uniformly boundary. Finally, simulation results validate the proposed method.

Byrnes-Isidori-based dynamic sliding-mode control for nonminimum phase hypersonic vehicles

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.

In this paper, a dynamic surface control (DSC) based adaptive fuzzy backstepping method is proposed for AUV (autonomous underwater vehicle) systems. The DSC is utilized to solve the “explosion of complexity” of traditional backstepping, the fuzzy logic systems(FLSs) are used to approximate unknown nonlinear function of AUV systems and the adaptive backstepping is employed to design controllers, and Matlab is used to conduct the simulation. The proposed control method can achieve position tracking effectively. The simulation results show that the adaptive fuzzy controller can overcome the influences of parameter uncertainties and load disturbance as well as achieve a good control effect on AUV system. This study has lots of practical application value.

In this paper, an adaptive nonlinear control scheme with a friction observer for position control of an electrohydraulic actuator is proposed. The observer based on the LuGre friction model is employed to compensate for the friction. Adaptation laws are used to handle parameter uncertainties in the actuator and friction model. The control law including dynamics of the observer is developed through a backstepping‐like dynamic surface control (DSC) technique. Experimental results have illustrated the success of the control scheme. The results also show that the adaptive DSC controller has better tracking performance than an adaptive backstepping and conventional PI controllers.

In this paper, for the six-degree-of-freedom (six-DOF) model of hypersonic flight vehicle (HFV) subject to actuator faults, state constraints, parametric uncertainties, and external disturbances, an adaptive fault tolerant control (FTC) scheme is proposed based on barrier Lyapunov functions (BLFs). The study is begun with a series of control-oriented manipulations: at first, due to the high complexity of the six-DOF model, the corresponding simplified model is proposed under reasonable assumptions; then, through the stability analysis of the internal dynamics, we can conclude that the vehicle model is a non-minimum phase system, namely, having unacceptable zero-dynamics. In order to solve the non-minimum phase problem, the elevator-to-lift coupling term is regarded as uncertainty of the model. Subsequently, in consideration of the insufficient control torque caused by the fault of the rudder or elevators, an adaptive fault-tolerant controller is designed based on BLFs, backstepping method, and Nussbaum gains. In the control law, the uncertain parameters are replaced by their estimates updated by adaptive laws. And the angle of attack and the roll angle of the aircraft are constrained in the preset range. Additionally, the convergence of the proposed FTC algorithm and the boundedness of all the signals of the closed system is proved by Lyapunov stability theory. At last, the numerical simulation results of the six-DOF model are carried out to manifest the effective tracking performance of the proposed FTC scheme.

This paper presents quaternion based twisting and backstepping controller for quadrotor. The quaternion model is free from singularity problem unlike the Newton Eulers model. There are two types of controller is designed, one for inner loop control and second is the outer loop control. In the proposed work inner loop controller is backstepping and outer loop control is twisting control. Inner loop control is also termed as attitude control. In attitude control reference velocity is generated using reference quaternion model. Both inner loop and outer loop controller are robust enough to handel disturbances. Stability is guaranteed using Lyapunov method. Simulation results are presented for different generated paths to show the advantage of the proposed method.

In this article, a fuzzy-approximation-based adaptive backstepping control method for dual-arm of a humanoid robot was proposed. The purpose of this control system is to provide coordinated movement assistance to enable the humanoid robot’s human-like forearm to grab objects coordinately (or track any continuous desired trajectory), even in the presence of environmental disturbances and parametric uncertainties. We analyze the proposed adaptive backstepping by mathematical modeling and actually measure the robot dual-arm motion information of a number of case when they simulate the trajectory to verify the model. We design the adaptive fuzzy-approximation control strategy and combining the synthesis of the robust design, backstepping control, and Lyapunov function method, the proposed adaptive fuzzy backstepping control does not need to know the humanoid robot’s arms model precisely. In the control system proposed here, once the desired trajectories of the robot’s dual-arm positions are given, the adaptive fuzzy system was closed to any unknown functions and to the derivative of the virtual control law of the humanoid robot system. In this case, a robust design scheme was utilized to compensate for any approximation errors. With the proposed trajectory tracking, not only able to generate the coordinate motions for a humanoid robot’s two arms, but it can also control the arms to move to the desired positions. The proposed closed-loop system under the adaptive fuzzy backstepping control design was effective and that asymptotic stability was successfully achieved. The adaptive fuzzy-approximation backstepping control strategy should be more complete and intelligent and more actual test should be conducted to further evaluate the effect of the proposed trajectory tracking. The instability of dual-arm of humanoid robot system is systematically analyzed and a backstepping control strategy based on the adaptive fuzzy-approximation to improve the continuity of trajectory tracking of the robot’s arms is proposed.

Back-stepping robust trajectory linearization control for hypersonic reentry vehicle via novel tracking differentiator

A novel backstepping control scheme based on the fixed-time observer is proposed for the attitude control of hypersonic morphing vehicles. A fixed-time observer is used to estimate the inertial matrix uncertainty and dynamic moments caused by span variation, aerodynamic coefficient uncertainty and external environmental disturbance. It ensures that the above disturbance estimation errors can converge to zero within a fixed time, and the convergence time is independent of the initial conditions of the hypersonic morphing vehicles. Furthermore, taking into account the effects of unmatched unknown nonlinear dynamics on the attitude tacking performance, a backstepping controller is designed to compensate for the above disturbances in the system. The stability of the closed-loop system is proved based on the Lyapunov function technique. Finally, the simulation results verify the effectiveness, reliability and accuracy of the proposed scheme.

Control of non-minimum phase (NMP) dynamic systems has been a widely and intensively studied challenging topic from its academic research to industrial applications. With the emergence of U-model based control system design, this study presents a new solution in designing such control systems. In technique, different from pole-zero cancellation (i.e. in force of multiplication/division), this study proposes a pulling principle (i.e. in force of summation/subtraction) to relocate zeros and poles through Infinite Impulse Response (IIR) filters, then introduces a U-model based universal control framework with invariant controller plus U-model inverter so that it separates the treatment of NMP issue from stable control system design. By integration of the above techniques, this study presents a systematic procedure to complement those classical approaches in designing NMP control systems. The associated properties and performance are proved analytically and demonstrated numerically (with Matlab simulation of bench test examples). To follow the study, the computational experiment results provide a user-friendly step by step procedure for the readers/users with interest in their ad hoc applications.

Impact angle-constrained integrated guidance and control for supersonic skid-to-turn missiles using backstepping with global fast terminal sliding mode control

A finite-time extended, state-observer-based, fixed-time backstepping control algorithm was designed for hypersonic flight vehicles. To enhance the robustness of the controller, two novel finite-time extended state observers were introduced to compensate for the negative effects of lumped disturbances such as uncertainties and external disturbances. Two hyperbolic sine tracking differentiators were used to approximate the derivatives of the virtual control signals and guidance commands, thereby alleviating the computational burden associated with traditional backstepping control. Furthermore, a fixed-time backstepping attitude controller was used to guarantee that the tracking errors converged to a small neighbor of the origin in fixed time. According to the simulation results, the proposed controller outperformed a fixed-time sliding mode disturbance, observer-based, finite-time backstepping controller in terms of the tracking precision and convergence rate. Moreover, the proposed controller was noted to be robust in simulations involving lumped disturbances.

This paper addresses the problem of fixed-time consensus tracking for a class of nonlinear multiagent systems (MASs) with disturbances. We establish a novel fixed-time consensus tracking protocol with adaptive disturbance rejection capabilities, leveraging adaptive selective disturbance elimination (ASDE) technology. This protocol consists of a distributed fixed-time observer (DFTO), a fixed-time disturbance observer (FTDO), and an adaptive selective disturbance elimination backstepping controller (ASDE) with adaptive lumped disturbance compensation abilities. The DFTO estimates the leader’s output using the communication network topology of each follower, while the FTDO rapidly observes the lumped disturbances and their derivatives. By adding disturbance indicator terms and disturbance observation attenuation terms to the control law, the beneficial and harmful effects of disturbance are distinguished. Under favorable disturbance conditions, lumped disturbances can be used to accelerate tracking speed. If disturbances are harmful, they are adaptively compensated to improve tracking accuracy. Furthermore, the fixed-time stability of each part of the protocol is analyzed using Lyapunov theory. Simulation results show that, under different initial states and command inputs, the proposed method achieves faster convergence and smaller tracking errors compared to the adaptive conditional disturbance negaton backstepping controller (ACDN), conditional disturbance negation backstepping controller (CDN), and non-smooth backstepping controller (NBCDC), verifying the effectiveness of the proposed method. The research outcomes serve as a reference for future multiagent adaptive anti-disturbance cooperative control technology.