Adaptive Output Regulation Research Articles

Adaptive Output Regulation of Heterogeneous Multiagent Systems Under Markovian Switching Topologies.

This paper investigates the adaptive output regulation problem for heterogeneous linear multiagent systems under randomly switching communication topologies. The switching mechanism is governed by a time-homogeneous Markov process, whose states correspond to all possible communication topologies among agents. A novel distributed adaptive cooperative controller is presented, where the dynamic compensators are utilized to estimate the exogenous signal for all the agents in mean square sense. The distributed control law is based upon the local information of agents, without using the global information of the communication topologies. Finally, illustrative examples are put forward to demonstrate the effectiveness of the given control scheme.

Cooperative adaptive output regulation for linear multi‐agent systems with actuator faults

This paper considers the cooperative fault-tolerant output regulation problem for linear multi-agent systems with actuator faults. It is assumed that the actuator faults are loss of effectiveness faults. A new lemma is introduced to ensure the transmission zero condition for the systems with actuator faults. Based on this lemma, the unique solution of the output regulation equations is achieved. Moreover, a distributed adaptive observer and a distributed state feedback controller with time-varying gains are designed to compensate the actuator faults. In addition, it is shown that the cooperative fault-tolerant output regulation problem can be solved under the proposed controller. Finally, a simulation example is presented to show the validity of the proposed controller.

Finite-dimensional Adaptive Error Feedback Output Regulation for 1D Wave Equation

This paper investigates the adaptive error feedback output regulation problem for 1D wave equation with harmonic disturbance anticollocated with control. We firstly construct an auxiliary system in which the control and the anti-collocated disturbance become collocated and the measured error becomes the output. Then we give the adaptive servomechanism design for the system by making use of the tracking error and the estimation mechanism for the parameters of the disturbances and tracking reference. This design does not base on the internal model principle and so have not any approximation. The control objective which is to regulate the error output to zero and to keep the states bounded is achieved.

Adaptive output regulation of invertible MIMO systems

The problem of output regulation for MIMO systems with harmonic exogenous inputs and parameter uncertainties is addressed. The issue of robust stability is handled, taking full advantage of all controls and all available measurements, by appealing to a general notion of “robust” minimum-phase. The classical internal model principle together with adaptive tuning loop is used to design the controller such that guarantees the asymptotic convergence of outputs to equilibrium point. An example of vessel control is given to illustrate the new approach.

The passivity of adaptive output regulation of nonlinear exosystem with application of aircraft motions

This paper deals with passivity of adaptive output regulation of nonlinear exosystem. It is shown that factorisable low-high frequency gains and harmonic uncertainties are estimated to the exogenous signals with adaptive nonlinear system. The design methodology guarantees asymptotic regulation in the case where the dimension of the regulator is sufficiently large in relation, which affects the number of harmonics acting on the system. On the other hand, harmonics of uncertain amplitude, phase, and frequency are the major sources, and the bounded steady-state regulation error ensures that adaptive nonlinear system is globally asymptotically stable via passivity theory. Kalman–Yacubovitch–Popov property provides that the uncertain adaptive nonlinear system is passive. Finally, specific examples are shown in order to demonstrate the applicability of the result.

Cooperative Adaptive Output Regulation for Second-Order Nonlinear Multiagent Systems With Jointly Connected Switching Networks.

This paper studies the cooperative global robust output regulation problem for a class of heterogeneous second-order nonlinear uncertain multiagent systems with jointly connected switching networks. The main contributions consist of the following three aspects. First, we generalize the result of the adaptive distributed observer from undirected jointly connected switching networks to directed jointly connected switching networks. Second, by performing a new coordinate and input transformation, we convert our problem into the cooperative global robust stabilization problem of a more complex augmented system via the distributed internal model principle. Third, we solve the stabilization problem by a distributed state feedback control law. Our result is illustrated by the leader-following consensus problem for a group of Van der Pol oscillators.

Adaptive Dynamic Programming and Adaptive Optimal Output Regulation of Linear Systems

This note studies the adaptive optimal output regulation problem for continuous-time linear systems, which aims to achieve asymptotic tracking and disturbance rejection by minimizing some predefined costs. Reinforcement learning and adaptive dynamic programming techniques are employed to compute an approximated optimal controller using input/partial-state data despite unknown system dynamics and unmeasurable disturbance. Rigorous stability analysis shows that the proposed controller exponentially stabilizes the closed-loop system and the output of the plant asymptotically tracks the given reference signal. Simulation results on a LCL coupled inverter-based distributed generation system demonstrate the effectiveness of the proposed approach.

Distributed Adaptive Consensus Output Regulation of Network-Connected Heterogeneous Unknown Linear Systems on Directed Graphs

This technical note deals with output regulation of network connected linear systems under directed connection graphs. The subsystem dynamics are unknown and heterogeneous. The desired output signal, generated by a linear exosystem, is only available to some subsystems, and the others will estimate the exosystem state through the network connections for obtaining regulation errors. The exosystem is parametrised in a specific form such that it has a skew-symmetric system matrix, whose property is further explored in the estimation of exosystem state, and in the estimation of the desired feed-forward control inputs for output regulation. The unknown subsystem parameters are dealt with by the adaptive laws, driven by the estimated regulation errors. The proposed adaptive control strategy is fully distributed, in the sense that the control design only uses the information in the connected neighbourhood, without reference to the eigenstructure of the associated Laplacian matrix, as long as the connection graph is strongly connected.

Adaptive output regulation for offshore managed pressure drilling

SummaryThis paper deals with output regulation problem for an offshore managed pressure drilling system subject to sinusoidal disturbances. The disturbance is caused by the heave motion of the floating drilling rig during pipe connections, and the objective is to maintain a constant pressure at the bottom of the well. The controller for the heave disturbance attenuation consists of three cascaded parts. First, a nonlinear inversion element is applied to invert nonlinearity of choke. Second, an adaptive compensator is designed based on internal model, and certainty equivalence principles for asymptotic rejection of time‐varying heave disturbance. Third, an output feedback controller is synthesized for providing stability and improving transient performance of closed‐loop system. Robust stability of closed‐loop system is analyzed using edge theorem. Simulation results of the combined adaptive output regulator are presented, which show satisfactory set‐point tracking and attenuation of the heave disturbance. Copyright © 2016 John Wiley & Sons, Ltd.

Data‐driven ALS‐SVR‐ARMA 2K modelling with AMPSO parameter optimisation for a high consistency refining system in papermaking

In this study, an innovative data-driven non-linear dynamical system modelling method, ALS-SVR-ARMA2K, is proposed for a high consistency refining (HCR) process in papermaking to online estimate the freeness index. First, to completely capture the non-linear dynamics of the process, the autoregressive moving average (ARMA) model is constructed by modelling system output as a non-linear dynamical function of the past system inputs (moving average) and past system output (autoregression). Then, the non-parametric kernel learning method, least squares support vector regression (LS-SVR), is presented for learning of the ARMA model. Moreover, to increase the modelling accuracy and make the model has both good interpolation and extrapolation abilities, improvements of multi-kernel learning and adaptive output regulation are implemented. Finally, to further enhance the modelling accuracy and efficiency of the constructed ALS-SVR-ARMA2K model, the adaptive mutation particle swarm optimisation (AMPSO) is proposed to optimise the hybrid model parameters. Industrial experiments and comparative studies have been carried out on an industrial HCR process, where it has been demonstrated that the developed AMPSO-ALS-SVR-ARMA2K model produces a better modelling accuracy, stronger generalisation capability and sparsity, and faster learning speed than the other methods. Moreover, these superiorities are especially true in the case of small samples.

L1 adaptive output regulator design with application to Managed Pressure Drilling

This paper presents a modification to L1 adaptive control that allows for disturbances entering at the output and application of this control strategy to Managed Pressure Drilling with harmonic disturbances representing the heave motion of a floating drilling rig. By incorporating the disturbance at the output into the closed-loop reference model, it is shown that the L1 adaptive control structure can be left unchanged while the original transient performance bounds are preserved. It is further shown that rejection of the output disturbance can be taken care of entirely in the filter design step of L1 adaptive control using the internal model principle. A systematic filter design procedure based on LMIs is provided, that requires only one tuning parameter to be adjusted by the designer. The control design is applied to disturbance attenuation and set-point tracking in the so-called heave problem in oil well drilling. We present experimental results of control system tests in a medium size test facility emulating a 900m long well.

A method for adaptive hybrid output regulation of linear systems

Abstract: In this paper we deal with the problem of adaptive output regulation for a class of uncertain hybrid linear systems whose state jumps periodically according to a known clock. The goal is to present a design methodology for internal model-based hybrid regulators in presence of hybrid exosystems that are unknown both in the flow dynamics and jump map, which are assumed to range in a finite set. The arguments used in this paper strongly rely on the ones recently presented in Cox et al. [2016] and, in particular, on the notion of visibility of the “hybrid steady-state generator”. The design methodology is then applied to the practical case of torque control of a DC-motor in presence of an uncontrolled rectifier.

Adaptive Cooperative Output Regulation for a Class of Nonlinear Multi-Agent Systems

In this technical note, an adaptive cooperative output regulation problem for a class of nonlinear multi-agent systems is considered. The cooperative output regulation problem is first converted into an adaptive stabilization problem for an augmented multi-agent system. A distributed adaptive control law with adoption of Nussbaum gain technique is then proposed to globally stabilize this augmented system. This control scheme is designed such that, in the presence of unknown control direction and large parameter variations in each agent, the closed-loop system maintains global stability and the output of each agent tracks a class of prescribed signals asymptotically.

Adaptive output regulation and circuit realization for a class of attenuated coupled networks

In this paper, an adaptive regulation method for couplings and its physical implementation are presented to deal with the problem of output synchronization of networks. The networks are supposed to suffer from a fault described by network attenuation. For the sake of eliminating the adverse impact of network attenuation, a self-regulating network is introduced by adjusting coupling strength based on adaptive technique. By using the Lyapunov stability theory for a synchronization error system, asymptotic output synchronization of the overall networks can be established for the attenuated couplings even without any control input. Moreover, based on the adaptive regulation strategy, an approach for application of knowledge of electricity is proposed to physically realize the self-regulating networks. Finally, numerical simulations on a Rössler oscillator network are given to illustrate the effectiveness of the derived results.

Adaptive consensus output regulation of a class of nonlinear systems with unknown high-frequency gain

This paper deals with adaptive consensus output regulation of a class of network-connected nonlinear systems with completely unknown parameters, including the high frequency gains of the subsystems. The subsystems may have different dynamics, as long as the relative degrees are the same. A new type of Nussbaum gain is proposed to deal with adaptive consensus control of network-connected systems without any knowledge of the high frequency gains. Adaptive laws and internal models are designed for the subsystems to deal with unknown parameters for tracking trajectories and unknown system parameters. In the control design, only the relative information of subsystem outputs are used, provided that regulation error of one of the subsystems is available. The proposed control inputs and the adaptive laws are decentralized. If the relative degree is one, only the relative subsystem outputs are exchanged. For the case of higher relative degrees, the nonlinear model structure of the subsystems is exploited for backstepping control design, and some variables generated by the subsystem controllers are exchanged among the subsystems in the neighbourhood defined by the connection graph.

Adaptive Add-On Output Regulator for Rejection of Sinusoidal Disturbances and Application to Optical Disc Drives

In this paper, we revisit an add-on output feedback controller that achieves output regulation and disturbance rejection. By add-on controller, we mean an additional controller, which runs harmonically with a preinstalled controller that has been in operation for the plant. When the disturbance attenuation performance of the preinstalled controller is not satisfactory, the add-on controller can be used to eliminate the disturbance. Some advantages of the proposed add-on controller include that it can be designed without much information about the preinstalled controller and it can be plugged in the feedback loop any time in operation without causing unnecessary transient response. In particular, we propose an adaptive add-on controller, which can eliminate sinusoidal disturbances of unknown frequencies. Both simulation and experimental results of the track-following control for optical disc drive systems confirm the effectiveness of the proposed method.

Cooperative Global Adaptive Output Regulation for Nonlinear Uncertain Multi‐Agent Systems with IISS Inverse Dynamics

AbstractThe cooperative global adaptive output regulation of nonlinear multi‐agent systems with unity relative degree was studied recently for the case where the inverse dynamics of the follower subsystems are input‐to‐state stable (ISS). In this paper, we present a further result by relaxing the ISS assumption to the integral ISS (iISS) assumption. As the iISS condition is strictly weaker than the ISS condition, our result applies to a larger class of nonlinear multi‐agent systems.

Global Robust Output Regulation of a Class of Nonlinear Systems with Nonlinear Exosystems and its Application

An adaptive robust output regulation design is proposed for the output feedback systems with a nonlinear exosystem. A new nonlinear internal model is first designed for the control input. The output feedback control design is further achieved based on a type of state filter which is designed for the transformed augmented system. The adaptive control technique is successfully incorporated in the stabilization design to ensure the global stability of the proposed control design for output regulation. The result is successfully applied to solve a tracking control problem associated with the well known Chua’s circuit.

Adaptive output regulation problem for a class of nonlinear systems

Adaptive output regulation problem for a class of nonlinear systems

Robust Helicopter Stabilization with Wind Disturbance Elimination

When a helicopter is required to hover with minimum deviations from a desired position without measurements of a persistent wind disturbance, a robustly stabilizing control action is vital. In this paper, the stabilization of the position and translational velocity of a nonlinear helicopter model affected by a wind disturbance is addressed. An estimate of the disturbance is introduced to be adapted using state measurements for control purposes. A nonlinear controller is then designed based on nonlinear adaptive output regulation and robust stabilization of a chain of integrators by a saturated feedback. While in the control synthesis the wind disturbance is assumed to be a sum of a fixed number of sinusoids with unknown amplitudes, frequencies and phases, a practical turbulence model is presented to the helicopter model in the control test. Simulation results show the effectiveness of the control design in the stabilization of helicopter motion and the built-in robustness of the controller in handling parameter and model uncertainties.