Control Theory Research Articles

Fixed-time reinforcement learning and optimal control design

This paper presents a fixed-time optimal control design approach using reinforcement learning (RL) that guarantees not only fixed-time convergence of the learning algorithm to an optimal controller but also fixed-time stability of the learned control solution. To ensure the former, zero-finding capabilities of the zeroing neural networks (ZNNs) are leveraged, and novel adaptive laws are presented accordingly. To ensure the latter, conditions on the cost function are provided for which its corresponding optimal controller assures the fixed-time stability of the closed-loop system. It is also shown that imposing a fixed-time stability constraint on the infinite-horizon optimal control solution actually solves the classical fixed-final-time (FFTM) finite-horizon optimal control problem. The Hamilton–Jacobi–Bellman (HJB) equation for the FFTM optimal control problem is time-varying, which makes it hard or even impossible to learn it directly online using RL. The presented approach bypasses this difficulty by developing an online solution for infinite-horizon optimal control problems under fixed-time stability constraints and with fixed-time convergent tuning laws. This approach makes learning and closed-loop system settling times predictable, tunable, and bounded. Simulation results for fixed-time optimal adaptive stabilization of a torsional pendulum system clarify this new design for nonlinear optimal control theory.

In good hands: A case for improving robotic dexterity.

Twenty-first-century roboticists envision robots capable of sorting objects and packaging them, of chopping vegetables and folding clothes. But although many today believe that the only factors necessary for robots to achieve dexterous manipulation are data and artificial intelligence (AI), managing all the mundane manipulations that humans perform daily requires constant adaptation to changing conditions. These operations include tasks demanding millisecond-level responses to prevent irreparable damage, such as quickly stabilizing a slipping package or halting a knife just before it cuts into a table. Although recent advances in intelligent robot control have considerably expanded-and will continue to expand-the range and complexity of tasks that robots can perform, AI, data, and control theory alone are not enough. A brain cannot manipulate items effectively without a body-and specifically hands-suited to the task.

The Role of Social Network on Social Isolation and Anxiety on Attentional Switching of Students.

The study is devoted to the study of the relationship between stress caused in students by social isolation and the ability to switch tasks as one of the basic functions of attention. The study draws on the theoretical background of The Attentional Control Theory as the most appropriate method to study the factors influencing attention control under the influence of the effects of stress. The experiment includes a sample of 76 Chinese university students who experienced forced social isolation for 6 months. A statistically significant increase in physiological markers of stress was found in both cases, indicating that social isolation leads to an accumulation of stress and an increase in the intensity of stress reactions when students reexperience social stress after isolation. The practical significance lies in changing the approach to coping with the results of social isolation stress in students through changing the method of presenting educational information.

Highly maneuvrable quadrotor unmanned aerial vehicle control with unknown disturbances

For the problems of highly maneuverable quadrotor unmanned aerial vehicle (UAV), such as drastic attitude changes, unknown model disturbances, and accurate velocity tracks, the paper proposes new model compensation control based on SO(3) according to the idea of model compensation control (MCC) theory and SO(3) theory. Accurate estimation for unknown disturbances and precise extraction of the reference signal are achieved by introducing compensation function observer and high-order differentiator. For the attitude solution, the desired attitude solutions based on acceleration are designed, which guarantees the range of accelerations is safely limited. At the same time, the relationship between attitude control, velocity control, and the desired attitude solutions is given. The proposed method not only has the global stability of SO(3) and the anti-disturbance stability of MCC but also improves the maneuverability of UAV. Through verifications of simulations and experiments, the proposed method not only has no loss of anti-disturbance performance but also significantly reduces overshooting and response time compared to traditional MCC methods. Providing a control strategy for highly maneuverable UAV.

Intelligent vehicle obstacle avoidance strategy application supported by fuzzy control theory

IntroductionWith the continuous progress of the automotive industry, the safe driving of intelligent vehicles has received increasing attention. Traditional obstacle avoidance techniques are not accurate enough in dealing with fuzzy information encountered in high-speed driving. Therefore, this study aims to improve the obstacle avoidance ability of intelligent vehicles through fuzzy control theory.MethodsThe study employs fuzzy control theory to enhance the ability of intelligent vehicles to process fuzzy information, thereby improving conventional obstacle avoidance techniques. A combination of visual sensing and ultrasonic detection equipment was used to comprehensively plan the real-time obstacle avoidance routes of the intelligent vehicle.Results and DiscussionThe improved obstacle avoidance technique achieves an accuracy of 96.11%, which is better than the comparison avoidance technique. In the absence of interfering signals, the running time and overshoot were 2.4 s and 7%, respectively, again superior to the comparison technique. The experimental results show that the obstacle avoidance technique proposed in this study can improve the recognition ability of intelligent vehicles on fuzzy information, so as to improve the accuracy of obstacle recognition and provide certain guarantee for the safe driving of intelligent vehicles.

Panic Buying: A Theoretical and Conceptual Review

Purpose: Panic buying is a consumer behaviour that can be complex to explain in critical, urgent, uncertain and crisis situations. This phenomenon has yet to be fully explored in research on consumer behaviour, and further investigation is required across a range of scientific fields. Panic buying may have many causes and consequences. Determining the causes of panic buying and understanding consumer psychology in crisis and disaster situations in terms of various theories can guide government officials, businesses, marketing practitioners and researchers in case it occurs again in consumer behaviour in the future. This study aims to conduct a conceptual and theoretical examination of panic buying and to focus on its causes. Material and Method: Panic buying was discussed conceptually and theoretically within the framework of the literature review and inferences were made. Findings: This study focuses on the conceptual and theoretical examination of panic buying and its causes. Theories such as Compensatory Control Theory, Social Influence Theory, Social Proof Theory, Scarcity Theory, Herd Behavior, Survival Psychology and Motivation Theory have been intensively the subject of studies on panic buying. It is more common in the literature to try to explain the reasons for panic buying during situations such as crises, pandemics and disasters. Results: Consumers who panic buy should be measured more in terms of their post-purchase feelings such as regret, sadness, empathy, satisfaction, and their intention to panic buying again. In addition, which marketing messages and strategies are more likely to cause panic buying and which strategies are more useful in controlling panic buying are also recommended for future research.

A Review on Mathematical Methods to Approximate µ-Values

In this article, we review a number of iterative and analytical techniques to approximate structured singular values or µ-values which is a straightforward generalization of singular values for square and rectangular matrices. The µ-value is a well-known tool which acts as a strong link between numerical linear algebra and control theory. The computation of structured singular value provides a platform to study and discuss stability, performance, and robustness of the system. Furthermore, we review some very important literature that discusses the applications of structured singular values in different areas of engineering.

Enhancing Student Engagement and Intellectual Development through Case-Based Instruction in Modern Control Theory

As technology advances at a breakneck pace, modern control theory has emerged as a vital component within the realm of engineering. This article endeavors to delve into the pedagogical transformation of modern control theory courses, leveraging case studies to align with the evolving educational landscape and nurture the learning interests and cognitive development of students in the contemporary era. By critically examining the challenges inherent in current teaching practices, the article introduces a suite of innovative instructional approaches and strategies designed to enhance students' grasp of theoretical concepts and hone their practical skills.

Context-dependent effects of morphosyntax processing in Turkish–Persian bilinguals: Electrophysiological and neuroanatomic correlates

Aims and objectives: Morphosyntax processing is related to the P600 event-related potentials (ERPs) component and blood-oxygen-level dependent (BOLD) activation of the Pars opercularis (PO). First, this paper aims to investigate the relation of these variables across individuals. Second, we consider the role of context in morphosyntactic processing. Design/methodology: Highly proficient Turkish–Persian bilinguals ( N = 33) made morphosyntactic judgments on sentences. In a monolingual context, only L2 sentences (Persian) were presented, and the electroencephalography (EEG) was recorded. In a bilingual context, Persian and Turkish sentences alternated, and functional magnetic resonance imaging (fMRI) was measured. Data and analysis: The EEG and fMRI data were taken from separately published experiments on the same participants. Here, we correlated amplitudes of EEG-derived ERP components and the number of activated voxels in fMRI in designated brain regions because both parameters are proportionally attuned to the number of activated neurons. Findings/conclusions: Morphosyntactic violations in a Persian monolingual context yielded a P600 component in the ERP. In L1, morphosyntactic violations increased BOLD activation in the left PO and in L2 they activated the posterior superior temporal gyrus (pSTG). The P600 amplitude correlated only with BOLD activity in the left PO for L1. These results first support a critical role of the PO in generating the P600; second, the findings are context-specific and are most pronounced for the presumed base languages in different contexts (i.e., L2 in monolingual and L1 in bilingual contexts). These results are consistent with predictions of the adaptive control theory. Originality: This study contributes to the rarely investigated interface between ERPs and fMRI in bilingual speakers during morphosyntactic processing. The results offer novel insights into language context effects. Significance/implications: Our findings highlight the importance of cross-modality neuroimaging in bilinguals and language processing in both monolingual and bilingual contexts.

Relaxed Positivity, η-Exponential Stabilization and l1-Gain Performance of Polynomial Discrete-Time Fuzzy System with Time-Delay and External Disturbance

The positivity constraint makes the stability for positive systems under the precise convergence decay and anti-disturbance performance quite challenging considering the current advanced control theory. Furthermore, the existence of time delay will disturb the dynamics of non-linear positive systems and even lead to a series of complex behaviours, such as oscillations and instability. With respect to the above problems, an approach of membership function-dependent positivity, η-exponential stability and l1-gain performance investigations which consider the dedicated membership function shape for the polynomial fuzzy discrete-time model (PFDM) with time-delay is proposed in this article. Firstly, we use a novel co-positive polynomial η-exponential Lyapunov–Krasovskii functional candidate to investigate the systems exponential stability under the decay η-rate and l1-gain anti-disturbance performance. Secondly, to reduce the conservativeness of conditions, a novel piecewise-polynomial membership function is used to introduce the Lagrange approximation knowledge into stability and performance analysis. Finally, the synthesized state-feedback fuzzy controller with polynomial terms guarantees these control objectives under positivity constraints. Two simulation examples validate the developed new method.

Study of repulsive permanent magnetic levitation mechanism and its dynamic characteristics

Permanent magnet magnetic levitation (PMFL) system has the characteristics of zero-power levitation, strong load-carrying capacity and self-stabilization, so it has obvious advantages in the application of rail transportation and heavy-duty transmission and other fields. However, due to the lack of active control of electromagnetism and the existence of multi-point coupling, it is easily affected by external factors, and its dynamic characteristics and its complexity. This paper aims to reveal the levitation mechanism of permanent magnet magnetic levitation system and the coupling motion law of bogie by combining theoretical analysis and experimental verification. Firstly, the proportional and exponential correction coefficients for the magnetic induction strength are introduced to establish an analytical model for the levitation force. Secondly, the three-dimensional dynamic characteristic model of the bogie is established by analyzing the running attitude and external disturbing factors, revealing the four-point levitation coupling mechanism, and judging its stability by using the motion control theory. On this basis, input and output decoupling is realized by the method of coordinate transformation. Finally, through simulation analysis and physical experiments, the bogie motion law under various complex working conditions is explored, and the validity and reliability of the research is proved.

Seismic design approach for steel K-shaped eccentrically braced frames

This paper aims to propose a design approach for K-shaped Eccentrically Braced Frames (K-EBFs) according to the Theory of Plastic Mechanism Control in α−θ plane (TPMC(θ)). The novelty is the use of a new kinematic design parameter to avoid undesired collapse mechanisms, i.e. the plastic rotation θ of the dissipative members. Despite an increase of computational burden, with TPMC(θ) it is possible to obtain shallower column sections and, therefore, cheaper design solutions rather than those obtained by means of the original approach in the α−δ plane where the design parameter was the top sway displacement δ of the structure. The TPMC is an optimal design approach to overcome limitations due to the application of the simplified design criteria suggested by the code. It is based on a solid theoretical background and proposed as a design tool of seismic-resistant structures able to failure by exhibiting a collapse mechanism of global type. The design of several structures with different height is herein proposed, and the accuracy of the design procedure is validated through both pushover ad Incremental Dynamic Analyses (IDA) performed using natural records.

Coercive Control in 2SLGBTQQIA+ Relationships: A Scoping Review.

Existing measures and theories of intimate partner coercive control largely evaluate men's coercion of women. The extent of knowledge pertaining to intimate relationships among other genders and sexual identities is unclear. Guided by a theoretical framework of intersectionality, we examined and synthesized original studies on coercive control by (perpetration) or against (victimization) Two Spirit, lesbian, gay, bisexual, trans, queer, questioning, intersex, and asexual individuals within intimate partner relationships. We searched eight academic databases for records from 2014 through 2022 and hand-searched review articles' reference lists, supplemented with gray literature and website searches. Using duplicate screening, we identified 1,774 unique documents; 526 met preliminary eligibility criteria and 277 were retained for data extraction in duplicate. Coercive control was more common among minority individuals and was related to mental health challenges. Few studies reported on gender- or sexual-identity specific forms of coercive control, and an intersectional focus was uncommon. This review revealed a lack of agreed definition of coercive control or accepted standard of measurement, and a gap in research with individuals who identify as gender diverse, gender fluid or intersex, or those identifying their sexuality as asexual, pansexual, or sexually diverse.

Pomelo fruit-picking robot for unstructured environments

Abstract The adoption of mechanized and intelligent harvesting equipment is an effective approach to enhancing the stability and competitiveness of the pomelo industry. This study presents the development of a harvesting device tailored for pomelos by improving target recognition algorithms and optimizing the picking mechanism. A fruit stem posture fitting algorithm based on the morphological characteristics of pomelos was developed, capable of obtaining spatial information on fruit stems even in obstructed environments. A serial PPRP picking mechanism with a fault-tolerant end-effector was designed, and kinematic equations and control theory models were established. Experimental results demonstrate that the workspace of the designed robotic arm for pomelo harvesting has a height of 1.9 meters and a depth of 1.3 meters, with a recognition accuracy of 94% and a picking success rate of 72%. The harvesting efficiency reached two fruits per minute, making the device suitable for operations in both structured and unstructured orchard environments.

Innovative Personalized Medicine for Immunosuppressive Drugs Based on Novel Control Theory of Pharmacokinetics

Tacrolimus is widely recognized as an anti-rejection agent due to its immunosuppressive characteristics. It binds to the immunophilin FK506-binding protein (FKBP) and thus to calcineurin, and inhibits its activity. Tacrolimus' therapeutic concentration range in blood is narrow, and its pharmacokinetics are highly variable among individuals. First, because tacrolimus primarily distributes to red blood cells (RBCs), anemia and blood transfusions can cause fluctuations in tacrolimus blood concentrations. Variations in blood tacrolimus concentration significantly correlated with variations in RBC count, hemoglobin level, and hematocrit value, but not with variations in white blood cell or platelet counts. Interestingly, FKBP played an important role in tacrolimus distribution to RBCs. The effects of intracellular and extracellular FKBP levels on RBC distribution of tacrolimus in circulating blood were substantial. Secondly, proteins affecting pharmacokinetics can differ at the genetic level in their expression and functional potency. Genetic polymorphisms that influence tacrolimus pharmacokinetics have been reported. A polymorphism in the gene encoding the metabolic enzyme cytochrome P450 (CYP) 3A5 is a particularly influential factor affecting tacrolimus pharmacokinetics in Japanese patients. CYP3A5 polymorphisms correlated with individual differences in tacrolimus blood concentration changes after starting continuous infusion in allogeneic hematopoietic stem cell transplantation (HSCT) recipients. In addition, CYP3A5*3 polymorphism also correlated with differences in the frequency of acute graft-versus-host disease (GVHD) development in allogeneic HSCT recipients.

Research on the Cutting Control Method of a Shield-Type Cutting Robot

With problems of low cutting efficiency, poor forming quality, and low control accuracy in large-section semi-coal rock roadway tunneling, comprehensive coal tunneling seriously lags behind fully mechanized mining. A fuzzy PID control method was proposed, taking the cutting robot in a shield-type tunneling system as the research object. Using mathematical analysis and other methods, a kinematic model of the cutting robot was established, and the pose transformation matrix of the cutting robot during the cutting process was obtained. A limit model for the motion space of the cutting robot cutting drum was established, and the motion relationship between the driving cylinder and the cutting drum was obtained. A fuzzy PID cutting robot control scheme was designed. The feasibility of the model was validated by simulation methods, and the correctness of the model and simulation was verified through on-site experiments. The results indicate that the established cutting robot model is correct, and the proposed fuzzy PID control method for the cutting robot is feasible. The maximum error of the center control of the cutting drum was 5.5 mm, and the average date was 0.89 mm, which was far less than the standard of 50 mm for engineering of the cross-section cutting of the roadway. This study enriches the control theory of shield-type cutting robots by improving control accuracy, enhancing the cutting efficiency of large-section semi-coal rock tunnels, ensuring the quality of section forming, and narrowing the gap between comprehensive coal tunneling and fully mechanized mining.

Juvenile justice at a crossroad between crime control and rehabilitation: A study of philosophies and practices in Austria and the United States

AbstractThis study examines philosophies and practices of juvenile justice in Austria and the United States specifically using cases of juvenile homicide to provide context to examine divergent outcomes in the two countries. Grounding the paper in the culture of control theory, findings indicate that Austria has not been as heavily influenced by punitive policies as has the United States and maintains a focus as a welfare state. Although the United States has made progress in parts of the juvenile justice system, for more serious offenses, it remains largely focused on crime control and punitiveness. Penalties for juvenile crimes, even the most serious cases, in Austria are geared toward resocialization, education, and treatment instead of punishment. Possible explanations for these differences are explored through local cultural and sociological examination.

Magnetostrictive Vibration Suppression via Integration of Current Amplification Negative Capacitor and Current Inversion Semi-Active Control Circuit

When attempting to suppress structural vibrations employing a magnetostrictive transducer, owing to the control force is generated from current, a larger amplification of the current entails superior control performance. The semi-active control theory uses the synchronized switching damping (SSD) technique for structural vibration suppression while requiring a minimal energy supply. However, the absence of external energy input limits the current amplification performance. To address this limitation, this study proposes a novel method that combines semi-active vibration suppression method with negative capacitance to improve the current amplification performance. The proposed circuit switches the circuit status between shunt, inductor-capacitor (LC) electrical oscillation, and negative capacitance circuits. A mathematical model was employed to analyze the current operation, suppression performance, and robustness of the proposed circuit. Further, machine learning and kernel regression model were employed to predict the optimal control force gain. Validation experiments conducted on a 10-bay truss structure identical to the simulation model show that the experimental results align with the simulation predictions. The vibration suppression rates of the proposed method under single-mode and multiple-mode vibrations reached 85.8% and 78.3%, respectively, which are 2.64 and 1.89 times higher than those achieved by conventional methods.

A mathematical framework for comparison of intermittent versus continuous adaptive chemotherapy dosing in cancer

Chemotherapy resistance in cancer remains a barrier to curative therapy in advanced disease. Dosing of chemotherapy is often chosen based on the maximum tolerated dosing principle; drugs that are more toxic to normal tissue are typically given in on-off cycles, whereas those with little toxicity are dosed daily. When intratumoral cell-cell competition between sensitive and resistant cells drives chemotherapy resistance development, it has been proposed that adaptive chemotherapy dosing regimens, whereby a drug is given intermittently at a fixed-dose or continuously at a variable dose based on tumor size, may lengthen progression-free survival over traditional dosing. Indeed, in mathematical models using modified Lotka-Volterra systems to study dose timing, rapid competitive release of the resistant population and tumor outgrowth is apparent when cytotoxic chemotherapy is maximally dosed. This effect is ameliorated with continuous (dose modulation) or intermittent (dose skipping) adaptive therapy in mathematical models and experimentally, however, direct comparison between these two modalities has been limited. Here, we develop a mathematical framework to formally analyze intermittent adaptive therapy in the context of bang-bang control theory. We prove that continuous adaptive therapy is superior to intermittent adaptive therapy in its robustness to uncertainty in initial conditions, time to disease progression, and cumulative toxicity. We additionally show that under certain conditions, resistant population extinction is possible under adaptive therapy or fixed-dose continuous therapy. Here, continuous fixed-dose therapy is more robust to uncertainty in initial conditions than adaptive therapy, suggesting an advantage of traditional dosing paradigms.

Improved modified gradient-based iterative algorithm and its relaxed version for the complex conjugate and transpose Sylvester matrix equations

Abstract In this article, we present two new algorithms referred to as the improved modified gradient-based iterative (IMGI) algorithm and its relaxed version (IMRGI) for solving the complex conjugate and transpose (CCT) Sylvester matrix equations, which often arise from control theory, system theory, and so forth. Compared with the gradient-based iterative (GI) (A.-G. Wu, L.-L. Lv, and G.-R. Duan, Iterative algorithms for solving a class of complex conjugate and transpose matrix equations, Appl. Math. Comput. 217 (2011), 8343–8353) and the relaxed GI (RGI) (W.-L. Wang, C.-Q. Song, and S.-P. Ji, Iterative solution to a class of complex matrix equations and its application in time-varying linear system, J. Appl. Math. Comput. 67 (2021), 317–341) algorithms, the proposed ones can make full use of the latest information and need less computations, which leads to higher computational efficiency. With the real representation of a complex matrix as a tool, we establish sufficient and necessary conditions for the convergence of the IMGI and the IMRGI algorithms. Finally, some numerical examples are given to illustrate the effectiveness and advantages of the proposed algorithms.