Output Feedback Control Research Articles

Static Output-Feedback Path-Tracking Controller Tolerant to Steering Actuator Faults for Distributed Driven Electric Vehicles

The steering system plays a critical role in the vehicle’s handling and directly influences its lateral dynamics. Faults or abnormal behavior in this system can affect performance, cause vehicle instability, and even lead to accidents. Therefore, considering these potential events is essential for designing robust controllers for autonomous vehicles. For this reason, in this work, a fault-tolerant path-tracking Static Output-Feedback controller is designed to handle steering actuator faults in autonomous vehicle steering systems. The controller adopts a Linear Parameter Varying approach to effectively handle nonlinearities associated with varying vehicle speeds and tire behavior. Furthermore, it only uses information from sensors, avoiding estimation stages. This controller can operate in two modes: a no-fault mode where only the steering is controlled to follow the reference path and a fault mode where the controller manages both the steering and torque vectoring. In fault mode, torque vectoring compensates for faults in the steering actuator. The design of the controller is completed considering gain faults in the steering system. The simulation results show that the proposed controller successfully maintains vehicle stability and significantly reduces tracking errors during high-risk maneuvers, achieving reductions of up to 50.65% in lateral error and 47.26% in heading error under worst-case fault scenarios.

Robust fuzzy output feedback control for a magnetorheological semi-active air suspension system with time-delay and actuator saturation

Magnetorheological fluid (MRF) dampers have been utilized in semi-active air suspension (SAAS) due to their attractive advantages. This paper investigates a novel robust fuzzy output feedback controller for semi-active air suspension with MRF damper (SAAS-MRFD), considering time delay and actuator saturation. An aero-thermodynamics theory is first utilized to describe the nonlinear air spring. The damping force of the MRF damper is represented by a hyperbolic tangent model. The interval type-2 (IT-2) Takagi–Sugeno (T-S) fuzzy method is second employed to capture those nonlinearities of the air spring and MRF damper. Considering the difficulty to measure all states, a novel dynamic output feedback (DOF) controller is developed by an appropriate Lyapunov–Krasovskii function and the reciprocally convex technique with consideration of time delay, actuator saturation, and output constraints. The effectiveness of the proposed controller is validated by both simulation and a quarter-car test rig (QCTR). The results indicate that the proposed controller has better performance in vibration reduction than the recent similar controllers in the literature.

Practical prescribed-time sliding-mode output feedback tracking control for heterogeneous vehicle platoon

This paper proposes a new output feedback tracking control for platoon systems of heterogeneous vehicles subject to nonlinear disturbances. First, a distributed prescribed-time extended-state observer (PTESO) is presented to estimate the unmeasurable system states and nonlinear disturbances. On this basis, a practical prescribed-time sliding-mode output feedback control (PPTSMC) law is designed, such that the constructed closed-loop system always guarantees its preset performance ability regardless of the initial conditions. Finally, the effectiveness and superiority of the developed method are verified by theoretical analysis and simulation.

Global output feedback stabilization of stochastic uncertain nonlinear systems with large constant delays

This paper studies the problem of output feedback stabilization for a class of stochastic uncertain nonlinear systems with large constant delays in state and input. For stochastic nonlinear systems, the maximal open sector Δ of output function is given. As long as output function belongs to any closed sector included in Δ, by constructing a reduced-order observer and C 2 Lyapunov–Krasovskii functional and using the homogeneous domination method, an output feedback controller can be developed to guarantee the closed-loop system globally asymptotically stable in probability.

Sliding Mode Fault-Tolerant Control for Nonlinear High-Order Fully Actuated Systems.

The high-order fully actuated systems (HOFASs) approach can only completely eliminate known nonlinearities. However, the practical systems often encounter unknown nonlinearities, including disturbances and faults. Therefore, this article studies a class of nonlinear HOFAS with component faults and disturbances. By applying the HOFAS theory, a novel integrated sliding mode fault-tolerant control strategy is proposed to ensure the stability of the closed-loop system. The state feedback and output feedback controllers are designed, respectively. For output feedback control, an extended state observer is designed to estimate system states. Once the HOFAS model is established, the designed controller and extended state observer can be directly implemented, facilitating the analysis and design of the control system. And the stability analysis does not depend on the complexity of the nonlinear functions. Finally, a numerical simulation example shows the effectiveness of the proposed method.

Composite-Observer-Based Adaptive Consensus Tracking Control for Nonlinear MASs With Unknown Control Directions Against Deception Attacks.

This article primarily studies the adaptive output-feedback consensus tracking control issue for nonlinear multiagent systems (MASs) with unknown control directions against deception attacks. First, a composite observer combining the state observer and the disturbance observer is developed to concurrently estimate the states of confronting deception attacks and unmeasurable disturbances. Moreover, to resolve the unknown gains resulting from deception attacks, the adaptive attack compensator is proposed. Furthermore, in view of the logarithm Lyapunov function in the final step of the design process and the intelligent approximation technique, a new composite-observer-based adaptive consensus tracking control strategy is constructed. The suggested control strategy ensures the boundedness of all the closed-loop signals while also achieving synchronous tracking of the leader's output by the followers. Last but not least, the effectiveness of the suggested control strategy is validated through two simulation examples.

State observers for output feedback control of electro-hydraulic systems

State observers for output feedback control of electro-hydraulic systems

Gyro-free attitude reorientation control of spacecraft with state and input constraints

This paper introduces an explicit reference governor-based control scheme to address the gyro-free spacecraft attitude reorientation problem, considering specific constraints such as pointing, angular velocity, and input saturation. The proposed control scheme operates in two layers, ensuring the asymptotic stability of the attitude while adhering to the aforementioned constraints. The inner layer employs output feedback control utilizing an angular velocity observer based on immersion and invariance technology. Through an analysis of the geometry associated with the pointing constraint, determination of the upper bound of angular velocity, and optimization of the control input solution, the reference layer establishes a safety boundary described by the invariant set. Additionally, we introduce the dynamic factor related to the angular velocity estimation error into the invariant set to prevent states from exceeding the constraint set due to unmeasurable angular velocity information. The shortest guidance path is then designed in the reference layer. Finally, we substantiate the efficacy of the proposed constrained attitude control algorithm through numerical simulations.

Event-triggered synchronization control for neural networks against DoS attacks

<p>This paper studied the event-triggered synchronization problem for time-delay neural networks under DoS attacks. A novel event-triggered scheme based on switching between periodic sampling and a continuous event-triggered scheme was proposed, which not only cuts down the number of data transmissions but also offsets cyberattacks. By choosing a suitable piecewise Lyapunov-Krasovskii functional and using several free-weighting matrices, sufficient conditions were established to ensure the exponential stability of the synchronization error system in the occurrence of DoS attacks. Furthermore, a co-design method was provided to acquire the desired non-fragile output-feedback control gain and event-triggering parameter. Finally, a numerical example was given to illustrate the usefulness of the proposed approach.</p>

Vehicle active suspension control considering parameter uncertainty and velocity variation

Due to the uncertainty in vehicle model parameters, the control performance of active suspensions often deteriorates, especially under extreme conditions such as high velocities and full loads. To address this challenge, this paper proposes a novel robust finite frequency H ∞ output feedback control strategy based on linear parameter varying (LPV) systems. First, we establish a new LPV model for the half-car active suspension control system, taking into account the uncertainties associated with vehicle velocity and sprung mass. Next, a robust finite frequency H ∞ output feedback controller is designed using a gain scheduling approach, formulated through a set of linear matrix inequalities (LMIs). Finally, simulation results demonstrate that the proposed velocity-dependent robust control strategy significantly reduces the root mean square (RMS) values of vertical acceleration by approximately 21% to 31% under various conditions of sprung mass and vehicle speed compared to traditional control methods.

Almost Dynamic Output Regulation for Switched T‐S Fuzzy Systems

ABSTRACTThis article studies the almost output regulation (OR) issue for switched Takagi–Sugeno fuzzy systems (T‐SFS) with the OR and the disturbance suppression properties simultaneously considered. A switched fuzzy dynamic output feedback controller (OFC) is firstly constructed for switched T‐SFS with modeled and unmodeled disturbances. By considering the average dwell‐time (ADT) constraint and introducing different coordinate transformations of subsystems, a solvability condition on the almost OR issue of switched T‐SFS is then established with the multiple Lyapunov functions method. Furthermore, the controller gains are designed to drive the switched T‐SFS to satisfy the OR and ‐gain properties. Finally, a simulation case is provided to validate the feasibility of the offered control technique.

Design of a Suspension Controller with Human Body Model for Ride Comfort Improvement and Motion Sickness Mitigation

This paper presents a method to design a suspension controller with a human body model for ride comfort improvement and motion sickness mitigation. Generally, it has been known that the vertical acceleration of a sprung mass should be reduced for ride comfort. On the other hand, recent studies have shown that, combined, the vertical acceleration and pitch rate of a sprung mass are key factors that cause motion sickness. However, those variables have been considered with respect to the center of gravity of a sprung mass. For motion sickness mitigation, the vertical acceleration of a human head should be also considered. In this paper, the vertical accelerations and pitch rates of a sprung mass and a human head are controlled by a suspension controller for ride comfort improvement and motion sickness mitigation. For the controller design, a half-car and human body models are adopted. With those models, several types of static output feedback suspension controller are designed with linear quadratic optimal control methodology. To reduce the pitch rate of the sprung mass and the vertical acceleration of the head, a filtered-X LMS algorithm is adopted as an adaptive feedforward algorithm and combined with the static output feedback controllers. A frequency response analysis and simulation are performed with the designed controllers on vehicle simulation software, CarSim®. From the simulation results, it is shown that the proposed controllers can effectively reduce the vertical accelerations and the pitch rate of the sprung mass and the human head.

Dynamic Event‐Triggered Output Feedback Control for a Class of Uncertain Nonlinear Systems

Dynamic Event‐Triggered Output Feedback Control for a Class of Uncertain Nonlinear Systems

Synchronisation of complex nonlinear dynamical networks with coupling delays via dual hybrid-triggered control design

The synchronisation problem for a class of complex nonlinear dynamical networks (CNDNs) that are subject to time-varying coupling delays and nonlinearities is explored in this work. This is accomplished by designing a dual hybrid-triggered communication technique based on the dynamic output feedback controller which is the main intent of this study. In contrast to the existing hybrid-triggered mechanism, a dual hybrid-triggered technique is being employed with the utilisation of outputs of considered CNDNs and the dynamic output feedback controller. To be precise, with an aim to effectively lower the network transmission rate in both the sensor-to-controller and controller-to-actuator channels, the triggering mechanism is implemented to both the outputs. Later, the Lyapunov–Krasovskii functional is utilised to establish the stability criterion and the necessary conditions for ensuring the synchronisation of chosen CNDNs are derived in terms of linear matrix inequalities. Eventually, two numerical examples, including the aircraft model have been rendered to reveal the potency of acquired theoretical results.

Global adaptive output feedback control of nonlinear time-delay systems with measurement uncertainty

Global adaptive output feedback control of nonlinear time-delay systems with measurement uncertainty

Finite-time stabilisation for a class of high-order uncertain planar systems with an output constraint via output feedback

This article is concerned with the output-feedback finite-time stabilisation problem for a class of high-order planar systems with unknown control coefficients, unknown measurement sensitivity and output constraint. The bounds of the unknown control coefficients and unknown measurement sensitivity are unknown, which prevent the construction of conventional constrained output-feedback finite-time controllers. Based on homogeneous systems theory, a simple constrained output-feedback finite-time controller is successfully constructed by utilising a new type of barrier Lyapunov function. Rigorous theoretical analysis suggests that the considered system under the proposed output-feedback controller is finite-time stable, and the requirement of output constraint is achieved. The innovative aspect of this control approach is its unification of the output-feedback finite-time stabilisation problem for high-order uncertain planar systems, addressing both scenarios with and without output constraints, all within a unified framework, without altering the established control structure. Finally, two examples are given to illustrate the effectiveness of the proposed control scheme.

Reinforcement learning-based adaptive optimal output feedback control for nonlinear systems with output quantization

Reinforcement learning-based adaptive optimal output feedback control for nonlinear systems with output quantization

Prescribed-time observer-based output feedback stabilisation of switched uncertain planar systems with asymmetric output constraints

This paper presents an observer-based output feedback control strategy to solve the prescribed-time stabilisation of uncertain planar switched nonlinear systems with asymmetric output constraints. Based on adding a power integrator technique, prescribed-time switched state feedback controllers and a common fractional-type barrier Lyapunov function are developed. Then, deliberately constructed prescribed-time switched reduced-order observers are presented to estimate the unmeasurable state. Combing the switched state feedback controllers and reduced-order observers proposed in this note, the closed-loop switched planar systems achieve prescribed-time stability. Meanwhile, the violation of asymmetric output constraints is prevented implicitly by the developed barrier Lyapunov function. The novelty of this approach lies in the ingenious construction of prescribed-time switched observers and the unified design characteristics of the method, which enable the accomplishment of prescribed-time output feedback stabilisation for switched systems with/without output constraints without necessitating any structure modifications to the switched controllers and observers.

Output Feedback Control for T‐S Fuzzy Markov Jump Systems Subjected to Parameter‐Dependent Dissipative Performance

ABSTRACTThis article is committed to the matter of asynchronous dynamic output feedback control for a class of Takagi–Sugeno fuzzy Markov jump systems. The principal concept is to construct a high‐level Markovian process governed controller under an asynchronous event‐triggered scheme and to develop a time‐varying dissipative index. As a salient feature that distinguishes it from the reported works with the common index, this paper firstly proposes a dissipative index with mode and membership functions‐dependence. Secondly, governed by the high‐level Markovian process, the asynchronous dynamic output feedback controller is constructed under the mode‐dependent partitioned regions. Meanwhile, to mitigate the communication pressure, an asynchronous dynamic event‐triggered mechanism is investigated with making allowances for the inaccessible system mode. What's more, as a first effort, this article presents a unified framework for co‐designing the strategy of asynchronous event generators and controllers. This is done under the proposed performance index and the mode‐dependent fuzzy state‐space partitions, resulting in more design flexibility. Based on the mode and region‐dependent Lyapunov functional, sufficient criteria are obtained to ensure the proposed dissipative performance and stochastic stability. Eventually, the practicabilities and advantages of the theoretic results are illustrated by a modified tunnel diode circuit model.

Output feedback control for non-strict feedback nonlinear systems: an adaptive fuzzy backstepping scheme

The adaptive fuzzy tracking control design issue is considered in this paper for a class of non-strict feedback nonlinear systems subject to external disturbances. A fuzzy high-gain state observer is constructed to reconstruct the unmeasurable states of the system by leveraging the universal approximation property of fuzzy logic systems for arbitrary unknown nonlinear functions. Within the framework of backstepping control design and in conjunction with adaptive techniques, an adaptive fuzzy control approach is presented. Subsequently, to work out the inherent ‘complexity explosion’ problem of the proposed control approach, dynamic surface control technique is introduced, leading to a simplified adaptive fuzzy output feedback control scheme. Stability analysis shows that the two proposed control schemes can ensure that all signals of the closed-loop system are semi-globally uniformly ultimately bounded, meanwhile the system tracking error can converge to a small neighborhood around the origin. Ultimately, a numerical simulation example is provided to validate the feasibility of the proposed control scheme.