Controlled System Research Articles

High Performance Bounded Finite Time Control for Linear Systems With Input Saturation

ABSTRACTReal‐world dynamical controlled systems are often subject to input saturation due to the physical constraints of actuators. This causes the response performance of the system to be degraded. To this end, we propose a high‐performance bounded finite time control (HP‐BFTC) method based on sliding mode control for finite time tracking of linear systems with input saturation. In this method, a novel concept of rate regulation finite‐time stability is proposed to achieve better steady‐state performance. A bounded controller based on sliding mode control is proposed to achieve finite‐time stability in rate regulation, wherein a finite time approach rate based on an inverse tangent function is presented to alleviate chattering caused by sign function, and two control parameters are introduced to improve response performance. The rate regulation finite‐time stability of the system is proved in the estimated domain of attraction. In addition, a parameter tuning principle is given to enhance the response performance of the closed‐loop system in transient and steady state. The superiority of the proposed method in performance is verified by a case study.

Quantum recharging by shortcut to adiabaticity

Quantum battery concerns about population redistribution and energy dispatch over controllable quantum systems. Under unitary transformation, ergotropy rather than energy plays an essential role in describing the accumulated useful work. Thus, the charging and recharging of quantum batteries are distinct from the electric-energy input and reuse of classical batteries. In this work, we focus on recharging a three-level quantum battery that has been exhausted under self-discharging and work extraction. We find that the quantum battery cannot be fully refreshed with the maximum ergotropy only by the driving pulses for unitary charging. For an efficient refreshment of the quantum battery, we propose a fast and stable recharging protocol based on postselection and shortcut to adiabaticity. More than accelerating the adiabatic passage for charging, the protocol can eliminate unextractable energy and is robust against driving errors and environmental decoherence. Our protocol is energy-saving and experimental-feasible, even in systems with forbidden transition.

New order-dependent conditions to control a class of nonlinear real-order systems

In many application points of interest, controlling the responses of real-world applications that vary with time seems quite challenging and puzzling. A linear time-varying state feedback controller is widely known and can be useful to estimate bounds to the state control matrix in the design of many control systems. The issue of initialization of real-order control system enhancement remains a challenging issue in the systems analysis subject to random initial-time placed on a real number line. We address a new design of a class of real-order control systems that consists of separated linear and nonlinear terms affected by input functions to be controlled with an implemented time-varying linear state feedback controller. We utilize the fractional comparison method and under Lipschitz nonlinearity with a constant bounding matrix of time-varying coefficients of control systems to address new order-dependent conditions that provide local and global stabilization to controlled systems. Applications of results that include practical real-order single-machine-infinite-bus power systems have been illustrated to control the responses by the utility of theoretical conditions examined along with validation of numerical simulations. It is shown that the proposed controller is practically convenient and demonstrates the efficiency of measuring the performances of control systems.

Adjusted linear quadratic regulator-proportional-derivative control of Quanser’s three degrees of freedom helicopter based on flower pollination algorithm under external disturbances

External disturbances, saturation of actuator motors, and limits of certain angular movements are commonly encountered in robotic systems, particularly those involving flight, and they present the most common and influential factors affecting the stability and performance of these systems. In this paper, a hybrid controller for a three-degree-of-freedom (3-DoF) helicopter is designed and applied to this flying robot system, taking into account the previously mentioned constraints. The proposed hybrid controller integrates proportional-derivative (PD) control with an adjusted linear quadratic regulator (ALQR) using the flower pollination algorithm (FPA) optimization method. Simulation results of travel (λ), elevation (ε), and pitch (ρ) responses, as well as experimental results of elevation and travel tracking responses under external disturbances using the bench-top Quanser’s (3-DoF) helicopter, demonstrate the robustness and good performance of the controlled system using the proposed method. The effectiveness of the proposed method is compared to several methods in the literature.

Optimal design and numerical studies of negative stiffness device–TMD controlled systems using PSO algorithm

In recent years, research on negative stiffness devices (NSDs) for vibration control has increased. This study examines the combination of NSDs with tuned mass dampers (TMDs) and explores the NSD-TMD as a nonlinear energy sink (NES). The particle swarm optimization (PSO) algorithm was employed to determine the optimal parameters for the TMD, NSD-TMD, and NES systems. The optimization procedure proves that the PSO algorithm is suitable for solving the optimization problem of the complex systems with strong nonlinearity. The overall procedure is effective and demonstrates strong convergence. The force transmissibility curves of the optimized systems were compared, revealing that the NSD-TMD achieved the best vibration performance, while the NES system demonstrated the target energy transfer (TET) property. Another interesting characteristic of the NSD-TMD system is that it does not necessarily require a large additional mass or damping factor to achieve optimal performance. An actual vertical vibration control scenario for a pedestrian bridge was analyzed using various control strategies. Human-induced force excitations were simulated using a code-defined method. The acceleration responses of an uncontrolled pedestrian bridge and the three optimized control systems were compared in both time and frequency domains. Results further verified the force transmissibility curves. The NSD-TMD system outperformed the other two systems, particularly in reducing the first-order response. Conversely, the NES system proved less effective for controlling human-induced vibration with harmonic force excitations.

Using Poly(amidoamine) PAMAM-βCD Dendrimer for Controlled and Prolonged Delivery of Doxorubicin as Alternative System for Cancer Treatment

Background/Objectives: Doxorubicin (Dox) is an anticancer drug used in the treatment of a wide range of solid tumors; however, Dox causes systemic toxicity and irreversible cardiotoxicity. The design of a new nanosystem that allows for the control of Dox loading and delivery results is a powerful tool to control Dox release only in cancer cells. For this reason, supramolecular self-assembly was performed between a poly(amidoamine) (PAMAM) dendrimer decorated with four β-cyclodextrin (βCD) units (PAMAM-βCD) and an adamantane–hydrazone–doxorubicin (Ad-h-Dox) prodrug. Methods: The formation of inclusion complexes (ICs) between the prodrug and all the βCD cavities present on the surface of the PAMAM-βCD dendrimer was followed by 1H-NMR titration and corroborated by 2D NOESY experiments. A full characterization of the supramolecular assembly was performed in the solid state by thermal analysis (DSC/TGA) and scanning electron microscopy (SEM) and in solution by the DOSY NMR technique in D2O. Furthermore, the Dox release profiles from the PAMAM-βCD/Ad-h-Dox assembly at different pH values was studied by comparing the efficiency against a native βCD/Ad-h-Dox IC. Additionally, in vitro cytotoxic activity assays were performed for the nanocarrier alone and the two supramolecular assemblies in different carcinogenic cell lines. Results: The PAMAM-βCD/Ad-h-Dox assembly was adequately characterized, and the cytotoxic activity results demonstrate that the nanocarrier alone and its hydrolysis product are innocuous compared to the PAMAM-βCD/Ad-h-Dox nanocarrier that showed cytotoxicity equivalent to free Dox in the tested cancer cell lines. The in vitro drug release assays for the PAMAM-βCD/Ad-h-Dox system showed an acidic pH-dependent behavior and a prolonged profile of up to more than 72 h. Conclusions: The design of PAMAM-βCD/Ad-h-Dox consists of a new controlled and prolonged Dox release system for potential use in cancer treatment.

Control problem for a parabolic system with disturbances and possible changes in dynamics

The problem of control of a parabolic system, which describes the heating of a given number of non-uniform rods, is considered. The control is point heat sources, which are located at the ends of the rods. Some boundary conditions are affected by uncontrolled disturbances. The density functions of the internal heat sources of the rods are not exactly known, but the segments of their change are given. We admit that at some moments of time, changes may occur in the equations describing the dynamics of the controlled system. These moments of time are not known in advance. The goal of choosing the control is to ensure that at a fixed moment of time, the weighted sum of the average temperatures of the rods belongs to a given segment for any admissible realizations of disturbances, unknown functions and moments of change in the dynamics. After the change of variables, this problem is reduced to a one-dimensional control problem with disturbance. Necessary and sufficient termination conditions are found.

A Petri net-based approach to robust deadlock prevention in automated manufacturing systems with unreliable resources

This paper studies the robust deadlock control issues in automated manufacturing systems (AMSs) with unreliable resources. The purpose of this paper is to synthesize a robust prevention supervisor to guarantee that the controlled system can operate smoothly when unreliable resources work well, and to ensure that parts that do not require any failed resources in their remaining routes can continue to be processed even if unreliable resources malfunction. In this paper, Petri nets (PNs) are employed to model the considered AMSs, which allow multi-quantity and multi-type of resource acquisitions. First, to avoid the resource’s underflow, a set of resource constraints denoted as a set of inequalities are developed based on the nominal capacity of shared resources and the minimal resource requirements of processes. Control places (monitors) are derived along with their control variables so as to resolve the blocking states caused by resource failures. Second, to guarantee the system’s liveness, a monitor is designed for each considered siphon in the different subnets derived from a system net. As a result, a robust prevention supervisor is synthesized for AMSs with unreliable resources. The effectiveness and superiority of our method are elucidated by some analyses and discussions.

Poly(Vinyl Alcohol) Drug and PVA-Drug-Surfactant Complex Organogel with Dimethyl Sulfoxide as a Drug Delivery System.

The relevance of active research lies in the need to develop new technologies to improve drug delivery methods for the effective treatment of wound healing. Additionally, the potential application of organogels in other areas of biomedicine, such as creating medical patches with controlled drug delivery, indicates a wide range of possibilities for using this technology. This study focuses on developing controlled drug delivery systems using organogels as carriers for ceftriaxone and ofloxacin. By selecting optimal formulations, organogels were created to immobilize the drugs, facilitating their effective and sustained release. The swelling behavior of the hydrogels was studied, showing a swelling coefficient between 16 and 32%, indicating their ability to absorb liquid relative to their weight. Drug release studies demonstrated that ceftriaxone was released 1.8 times slower than ofloxacin, ensuring a more controlled delivery. Microbiological tests confirmed that the organogels containing ofloxacin exhibited antimicrobial activity against Escherichia coli, Bacillus subtilis, and Staphylococcus aureus. However, it was a challenge to estimate activity for the model antibiotic ceftriaxone due to bacterial resistance to it. Organogel poly(vinyl alcohol) (PVA)-DMSO-alginate modifications with surfactant cetylpyridinium bromide led to the formation of a polyelectrolyte complex on the interphase, allowing further enhanced the prolonged release of the drugs. The research identified that the optimal compositions for sustained drug release were organogels with compositions PVA (10%)-PVP (1%) DMSO (50%) and PVA (10%)-DMSO (50%) formulations, illustrating the transparent nature of these organogels making them suitable for ophthalmological application. Various organogels compositions (PVA-DMSO, PVA-poly(vinylpyrrolidone)-DMSO, PVA-DMSO-alginate, PVA-DMSO-PLGA, PVA-DMSO-drug-surfactant) loaded with ceftriaxone, ofloxacin, and surfactant were prepared and characterized, highlighting their potential use in antibiotic patches for wound healing. These organogels illustrate promising results for localized treatment of infections in wounds, cuts, burns, and other skin lesions.

Ultimately bounded control for nonlinear systems under denial-of-service attacks: an accumulation-based event-triggered mechanism

This paper investigates the control problem for nonlinear systems under denial-of-service (DoS) attacks. In contrast to traditional event-triggered mechanisms (ETMs), an accumulation-based ETM, which is robust to abrupt signals, is employed to schedule the signal transmission between sensors and controllers, thereby saving more communication resources. Due to the openness of network-based transmission, DoS attacks are encountered during data transmissions, where the DoS attacks considered in this paper follow the Bernoulli distribution. This paper aims to design a controller for nonlinear systems considering the impact of DoS attacks and accumulation-based ETMs, ensuring that the controlled system state is ultimately bounded in the mean square. Firstly, sufficient conditions are provided to guarantee that the system state can achieve the given control performance, along with an explicit expression for the ultimate bound. Then, the controller gains are obtained by solving certain linear matrix inequalities. Finally, two simulation examples are conducted to validate the effectiveness of the designed controller.

Dynamic estimation of an object's center-of-mass direction: a novel control method for robotic interaction in uncertain environments

To operate in uncertain environments, robots must dynamically interact with and recognize objects. This paper proposes a novel control method to dynamically estimate the center-of-mass of an uncertain object. In this method, a robot finger moves an object, and the moving direction of the finger is dynamically adjusted to estimate the direction of the object's center-of-mass (friction center). The primary advantage of this method is its capacity to rapidly estimate the center-of-mass direction utilizing a single contact. Once the direction of the center-of-mass is determined, this information can be used, for example, for the robot hand to grasp the object securely by surrounding its center-of-mass, ensuring stable handling without unexpected movements. Moreover, determining the center-of-mass can aid in automatically producing training data for machine learning applications. Both simulation and experimental results validate the proposed control method's efficacy, demonstrating its ability to quickly converge to the desired state. This control problem poses a significant challenge as the system has fewer actuators than degrees of freedom, indicating that this controlled system is underactuated. Nonetheless, the proposed control method operated successfully.

Tube-based integral sliding mode predictive control scheme for constrained uncertain nonlinear time-delay system

For a class of constrained uncertain nonlinear time-delay systems, how to achieve their stability and robustness is a crucial issue. To this end, this paper proposes a tube-based integral sliding mode predictive control scheme (ISMPC). The model predictive control (MPC) is designed as a nominal controller to generate an optimal ‘reference trajectory’ for the actual (controlled) system. The integral sliding mode control (ISMC) acts as an auxiliary controller to combat disturbances and ensure that the actual trajectory is restricted in a robust tube centred on the reference trajectory. In addition, during the design process, the practical constraints are satisfied through the sliding mode boundary layer, without the need for iterative computation of robust invariant sets. The proposed control scheme combines the advantages of model predictive control MPC and ISMC, ensuring the optimal performance and robustness of the controlled system, and effectively reducing the computational burden required for the control scheme. Finally, the stability of the closed-loop system is proved theoretically, and the effectiveness of the proposed method is verified by the simulation results of two examples.

A review on exploring the potential of PVA and chitosan in biomedical applications: A focus on tissue engineering, drug delivery and biomedical sensors.

Polymers have been integral to the advancement of biomedicine, owing to their exceptional versatility and functionality. Among these, polyvinyl alcohol (PVA) and chitosan both natural polymers stand out for their remarkable biocompatibility, biodegradability, and unique properties. This review article provides a comprehensive examination of the diverse applications of PVA and chitosan in three pivotal areas: tissue engineering, drug delivery, and biosensors. In tissue engineering, the discussion centres on how PVA and chitosan are engineered into scaffolds that not only support cell growth and differentiation but also promote tissue regeneration by closely mimicking the extracellular matrix. These scaffolds offer the necessary mechanical strength and adaptability for various biomedical applications. For drug delivery, the article delves into the development of sophisticated controlled release systems and targeted drug carriers, highlighting the polymers' customizable properties and their mucoadhesive nature, which make them highly effective across multiple drug delivery methods. Furthermore, the potential of PVA and chitosan in biosensor technology is explored, particularly their ability to interact with biomolecules and their intrinsic conductivity attributes that are essential for creating sensitive, reliable, and biocompatible sensors for medical diagnostics. By synthesizing recent research findings and suggesting future research directions, this review underscores the versatility and critical role of PVA and chitosan in pushing the boundaries of biomedical innovation. It offers valuable insights for researchers and scientists dedicated to advancing healthcare through the application of these natural polymers.

A review of research on optical true time delay technology

Light controlled phased array has the advantages of fast response speed, compact system, diverse functions, and flexible control, and has been widely applied in many scientific and technological fields. Optical true delay technology (OTTD) is the most direct technical means to achieve phase delay of optical carrier signals, and it is also the most basic technical means to implement optical controlled beamforming systems. In order to fully understand the optical true delay technology, this article first elaborates on the principle of phased array antennas and the reasons for beam strabismus, and analyzes the impact of true delay on the performance of phased array radar. Then, the basic principle, technological progress, and related applications of optical true delay are introduced. Taking four common structures of optical true delay lines as examples,which are micro-ring resonant cavity array, grating ture time delay line, multi-path switchable optical ture time delay line（OTTDL）, and wavelength selective optical delay line, their performance in delay accuracy, adjustable delay range, and frequency bandwidth are compared. Finally, the current problems and future development trends of optical controlled beamforming technology were summarized.

Model-Following Preview Control for a Class of Linear Descriptor Systems with Actuator Failures

This paper considers the model-following preview control problem for a class of continuous-time descriptor systems with actuator failures. Firstly, the model-following problem is transformed into an optimal preview control problem by utilizing restricted equivalent transformations and the construction of augmented systems. After discussing the relationship between the stabilizability and detectability of the augmented system and the corresponding characteristics of the controlled system, the model-following preview controller of the original descriptor system is obtained by integrating on the controller of the augmented system. Finally, an application to electrical circuit system is used for assessment purposes. The simulation results demonstrate the effectiveness of the proposed controller.

Relaxed optimal control problem for a finite horizon G-SDE with delay and its application in economics

This paper investigates the existence of a G-relaxed optimal control of a controlled stochastic differential delay equation driven by G-Brownian motion (G-SDDE in short). First, we show that optimal control of G-SDDE exists for the finite horizon case. We present as an application of our result an economic model, which is represented by a G-SDDE, where we studied the optimisation of this model. We connected the corresponding Hamilton–Jacobi–Bellman equation of our controlled system to a decoupled G-forward backward stochastic differential delay equation (G-FBSDDE in short). Finally, we simulate this G-FBSDDE to get the optimal strategy and cost.

Minimum-Time Control of a Linear System With Input Saturation: A Practical Approach

Abstract A simple algorithm is presented to find near-minimum-time control inputs for a controllable continuous-time linear time-invariant system with any number of states and inputs. The well-known digital deadbeat control algorithm is modified to satisfy input constraints, and the design issue is the selection of sampling period to minimize the time required to reach the desired final state. During each sampling period, the input required to place all the poles at the origin of z-plane (deadbeat control) via state feedback is computed. If the infinity norm of the deadbeat input exceeds the input constraint, the input is found by placing the poles as close to the origin as possible. A sufficient condition for the system stability is developed. Numerical examples illustrate that this algorithm can lead to true time-optimal control or near time-optimal control.

Review on advanced drug delivery systems: innovations in formulation and delivery technologies

Advanced drug delivery systems (DDS) have transformed the pharmaceutical landscape, offering innovative solutions to enhance therapeutic outcomes and patient compliance. This review explores recent advancements in formulation technologies and delivery mechanisms, focusing on nanotechnology, polymeric systems, solid lipid nanoparticles (SLNs), and microparticle-based formulations. Nanotechnology has enabled the development of nanoparticles, liposomes, and nanocrystals that enhance drug solubility, stability, and targeted delivery. Polymeric drug delivery systems, including biodegradable polymers, offer sustained drug release, significantly improving chronic disease management and cancer therapy. SLNs and nanostructured lipid carriers (NLCs) provide stable matrices for drug encapsulation, particularly for lipophilic drugs, while microparticle-based formulations offer controlled and sustained drug release, reducing dosing frequency and enhancing patient compliance. Furthermore, novel delivery mechanisms such as transdermal systems, oral controlled release systems, targeted drug delivery, and inhalable therapies have expanded the possibilities for non-invasive, patient-friendly drug administration. Challenges in scaling up production, regulatory approval, and long-term safety remain significant, but emerging technologies like nanobots and bioengineered tissues hold promise for the future of personalized medicine. As these advanced delivery platforms continue to evolve, they are poised to revolutionize drug delivery, offering more precise, effective, and patient-centric treatments.

Performance and Robustness of Physiological Controllers With Integrated Pressure Sensors on Inflow Cannula.

The control of left ventricular assist devices (LVADs) requires sensors and/or estimators to account for the physiological state of the patient and apply advanced controllers. Sensor characteristics are a challenge when using implantable pressure sensors because they influence the quality of physiological control and the robustness of the controlled system. The objective of this work is to investigate the performance and robustness of LVAD controllers that operate based on LVAD integrated pressure sensors. Four pressure-based LVAD controllers are tested with a HeartMate 3 that has an integrated pressure sensor. Controller sensitivity as well as robustness to sensor drift and noise are evaluated based on controller response to large changes in preload and afterload. A fail-safe strategy for sensor failure used also to investigate the reliable operation of the LVAD in realistic conditions. All tested controllers are sensitive to drifting pressure signals, which can lead to unstable behavior. The results show that two controllers are robust to noise. The other two controllers show high deviation and oscillation in cardiac output even for small noise. Additionally, a noticeable difference of the controller's response between simulated and measured pressure input was observed, indicating the need for a robust controller design. Reliable operation even in the event of a sensor failure was achieved on the basis of a fail-safe control system.

Dynamic inversion and optimal tracking control on the ball-plate system based on a linearized nonholonomic multibody model

This paper addresses the optimal control of the ball-plate system, a well-known nonholonomic system in the context of nonprehensile manipulation, using a multibody dynamics approach. The trajectory tracking control of a steady-state circular motion of the ball on the plate, for any radius and potentially off-centric with respect to the plate’s pivoting point, is achieved by designing a Linear-Quadratic Regulator. A spatial multibody model of the ball-plate system is considered. A key contribution is the analytical computation of the circular steady motion of the ball by dynamic inversion, including the control actions to achieve this reference solution. This enables the analytical computation of the linearized equations along this reference motion, resulting in a periodic linear time-varying (LTV) system, and the application of linear controllability criteria for LTV systems. A controllable linear system, involving the Cartesian coordinates of the contact point and the yaw angle of the sphere, is obtained using a convenient coordinate partition in the linearization. Compared to existing results on the same problem, closed-loop stability about the desired trajectory is achieved for any radius of the circular trajectory.