Adaptive Digital Disturbance Rejection Controller Design for Underwater Thermal Vehicles

In this paper, a multivariable adaptive disturbance rejection scheme is developed for solving the nonlinear aircraft turbulence compensation problem. A nominal design for output rejection of unmatched input disturbances is first constructed based on feedback linearization, for which the relative degree characterization of the control and disturbance system models is specified as a key design condition for turbulence compensation designs. Adaptive disturbance rejection control is then completed by deriving an error model in terms of parameter errors and tracking error, and constructing an adaptive law for updating the controller parameters. All closed-loop signals are guaranteed to be bounded and the plant output tracks a given reference output asymptotically despite the uncertainties of system and disturbance parameters. A nonlinear turbulence compensation design is studied for an aircraft system model, and simulation results from this benchmark aircraft model verify the desired system performance.

ABSTRACTAn adaptive disturbance rejection control scheme is developed for uncertain multi-input multi-output nonlinear systems in the presence of unmatched input disturbances. The nominal output rejection scheme is first developed, for which the relative degree characterisation of the control and disturbance system models from multivariable nonlinear systems is specified as a key design condition for this disturbance output rejection design. The adaptive disturbance rejection control design is then completed by deriving an error model in terms of parameter errors and tracking error, and constructing adaptive parameter-updated laws and adaptive parameter projection algorithms. All closed-loop signals are guaranteed to be bounded and the plant output tracks a given reference output asymptotically despite the uncertainties of system and disturbance parameters. The developed adaptive disturbance rejection scheme is applied to turbulence compensation for aircraft fight control. Simulation results from a benchmark aircraft model verify the desired system performance.

This work deals with the control issue in disturbed discrete-time nonlinear nonaffine system. A novel adaptive nonlinear active disturbance rejection control based on dynamic linearization technique is designed. Through dynamic linearization technique, the nonlinear nonaffine system is translated into a linear parametric data model with a nonlinear uncertainty. The estimations of unknown parameter and the nonlinear uncertainty are proposed by using an adaptive law and an extended state observer, respectively. By considering parameter adaptation, the dynamics of reference trajectory, the uncertainty compensation, and nonlinear error feedback simultaneously, an adaptive nonlinear error feedback control law is proposed. The final simulations verify the practicability and the validity of the proposed control scheme.

In this article, the trajectory tracking control of a solar tracking system is tackled by means of an adaptive active disturbance rejection control scheme. The state and disturbance estimation system is based on the combination of a time varying identification system and an adaptive observer. The stability and robustness of the controller is mathematically tested by means of the second method of Lyapunov, and its effectiveness is experimentally tested in a robotic test bed, achieving both lower energy consumption and better tracking results with respect to a PID-based controller.

This paper investigates an adaptive disturbance rejection control (ADRC) strategy for dual-variable power smoothing for hydraulic wind turbine systems deployed in marine environments. Initially, fluctuations in wind speed induce variations in the output torque and rotational speed of the wind turbine; this study examines the interaction between these two variables and subsequently decouples them. An innovative dual-variable anti-disturbance control strategy is proposed, which independently regulates the pitch angle of the rotor and the swing angle of the variable motor to mitigate fluctuations in both speed and torque, thereby achieving a smoother system output power. The simulation results obtained through MATLAB/Simulink (Version R2022a) indicate that employing the proposed control strategy leads to an 8.31% reduction in power generation compared to optimal power tracking strategies while enhancing output power stability by 56.67%. Furthermore, the effective smoothing of power fluctuations is accomplished without necessitating energy storage devices. Finally, the effectiveness of the power smooth output control strategy proposed in this paper was verified based on a semi-physical simulation experimental platform for a 30 kW hydraulic wind turbine. The control method proposed in this paper provides a theoretical basis for the promotion and application of hydraulic wind turbines with stable power output.

An adaptive active disturbance rejection controller is used in the current driver design of the electromagnetic coil. Extended state observer of the 1st‐order system is adopted for disturbance observation of ADRC. The supervised recursive least squares method is proposed for real‐time parameters estimation, in which the excitation signal variance is used to trigger the parameter estimator. The experimental results demonstrate that ADRC combined with real‐time parameter estimation simplifies the parameter tuning and improves the parameter adaptive ability.

Adaptive synchronization with disturbance rejection for under-actuated ships with disturbances under thruster saturation

Digital adaptive controllers are widely used for active noise control. The secondary path delay, including the anti-aliasing, sampling, and reconstruction effects, must be shorter than that in the primary path to maintain good broadband performance. To eliminate the added delay of the sampling, a mixed analog and digital adaptive feedforward controller is developed. The analog controller is based on a state-filtered adaptive linear combiner, while the digital one uses an adaptive finite-impulse-response filter. The adaptation of the analog controller is derived based on a sampled version of the normalized projection algorithm, while the digital controller adaptation is based on the filtered-reference least-mean-squares algorithm. Two configurations are considered for the analog combiner. One aims to minimize the electrical noise by introducing individual state filters, all driven by the same reference signal. The other gives a superior bandwidth by driving each component filter with the previous filter output. The performance of the proposed controller is assessed and compared with separate analog or digital controllers. The results highlight that the suggested controller obtains significant attenuation levels close to the causality limit using the analog controller but also allows long impulse responses using the sampled controller.

This paper proposes a new adaptive fuzzy active disturbance rejection control design technique on permanent magnet synchronous motor (PMSM). Fuzzy logic control is applied to adjust the proportional coefficient of nonlinear proportional error control (NLPE). The extended state observer (ESO) is used to track and estimate the uncertainty of PMSM system including unmodeled dynamics, load disturbances and parameter perturbations. The control variable put into system can be obtained through subtracting the estimator of ESO from the output of NLSEF adjusted online by using fuzzy logic control and. The simulation results show that the proposed control strategy operates robustly under modeling uncertainty and external disturbances and has good dynamic performance.

Robust Control based on ADRC and DOBC for Small-Scale Helicopter

Direct adaptive rejection of unknown time-varying narrow band disturbances applied to a benchmark problem

The paper considers the problem of compensation for unknown external disturbances for a class of linear stationary multidimensional systems with distinct input delays. It is assumed that external disturbances are harmonic signals with unknown frequencies, phases, amplitudes, and biases that simultaneously affect both the input and output of the system. To solve the problem, the direct disturbance compensation method based on the internal model principle is used in combination with the classical Falb-Wolovich linear state feedback decoupling method which allows increasing the convergence rate of output signals with a small adaptation parameter. In order to eliminate cross-interactions between control loops, the channel decoupling method based on Falb-Wolovich linear state feedback decoupling approach is applied to the system. Then, an observer is constructed to estimate the state vector of the external disturbance model and, based on the estimations, an adaptive control law with the memory regressor extension is designed to compensate for external disturbances based on the internal model principle. The system is stabilized simultaneously with the decoupling of control channels, which allows one to proceed to the problem of compensating for external unknown disturbances, bypassing the design phase of the stabilizing component of the control signal. There are no restrictions on the observability and stability of the control plant. An adaptive algorithm with the memory regressor extension combined with the Falb-Volovich linear state feedback decoupling method is proposed to compensate for unknown external disturbances for a class of linear stationary multidimensional systems with distinct control delays. The efficiency of the proposed approach is illustrated by an example of numerical simulation in the MATLAB/Simulink environment. The resulting transient response plots demonstrate that the proposed algorithm ensures the boundedness of all closed-loop signals and the asymptotic stability of the output variables in the presence of distinct input delays under external harmonic disturbances. The proposed approach allows obtaining an improved rate of convergence of processes and can be applied in engineering systems and complexes the mathematical description of which is given in the form of linear multidimensional systems with distinct input delays.

In this article, an adaptive dynamic surface control method with nonlinear disturbance observers is proposed for accurate position tracking of an electro-hydraulic servo system with unknown time-varying inner or external disturbances. The dynamic surface control approach adopted in the proposed controller is used to ameliorate the inherent complexity differentiation explosion of traditional backstepping method, which significantly simplifies the controller design process. The designed nonlinear disturbance observers are exploited to online estimate the inner or external disturbances of electro-hydraulic servo systems, and the performance degradation resulted from unknown time-varying disturbances is effectively suppressed. To further compensate for the system’s time-varying uncertain parameters, parameter adaptive updating laws are designed and combined in the proposed controller for accurate position tracking of electro-hydraulic servo systems. The closed-loop stability of the proposed controller is theoretically guaranteed by rigorous Lyapunov analysis. Comparative experimental results are carried out on a typical single-degree-of-freedom electro-hydraulic servo system, and the feasibility together with the superiority of the proposed controller is experimentally validated.

This paper presents an adaptive disturbance rejection (ADR) controller developed for the suppression of the pathological tremor in the humans’ wrist. An experimental setup, based on a slotted permanent magnet linear motor (PMLM), was developed to evaluate the ADR’s performance in real-time suppression of the tremor signal recorded from Parkinson’s disease patients. A model-base compensator was utilized to minimize the resistive and cogging forces exhibited by the PMLM. Experimental results showed an average tremor amplitude suppression of 32.61 dB (97.6%) in the first, and 15.23 dB (82.7%) in the second tremor frequency respectively. The average magnitude of the resistance force induced by the system against voluntary motion was 0.36 N. Furthermore, to evaluate the tremor suppression performance of the presented technique the results were compared with two other studies that used pneumatic actuators and magneto-rheological dampers (MRD). The performance of the PMLM was analogous to actively controlled pneumatic actuators and was significantly better than the semi-active controller with MRD.

A digital adaptive controller is applied to the active flutter suppression problem of a wing under time varying flight conditions in subsonic and transonic flow. Linear quadratic controller gain at each time step is obtained using an iterative Riccati solver. The digital adaptive optimal controller is robust with respect to the unknown external loads. Flutter and divergence instabilities are simultaneously suppressed using a trailing-edge control surface and displacement sensing. A new transonic unsteady aerodynamic approximation methodology is developed which enables one to carry out the rapid calculation required for transonic aeroservoelastic applications. This approximation is based on a combination of unsteady subsonic aerodynamics combined with a transonic correction procedure. Aeroservoelastic transient time response is obtained using Roger's approximation, state transition matrices and an iterative time marching algorithm. The aeroservoelastic system in the time domain is modeled using a deterministic ARMA model together with a parameter estimator. Transonic flutter boundaries of a wing structure are computed, in the time domain, using an estimated aeroelastic system matrix and are in good agreement with experimental data for the low transonic Mach number range.