Integral Feedback Research Articles

Experimental study on an enhanced integral force feedback controller for active damping

In this paper, an enhanced integral force feedback controller is proposed for implementing active damping. Compared with the classical integral force feedback, the pure integrator is replaced with a combination of a first-order low-pass filter and a proportional term. The control performance of the proposed controller is examined on a single-degree-of-freedom host system. In order to better understand the physics behind, a full equivalent mechanical model is derived. It is found that the first-order low-pass filter is mechanically equivalent to a spring and a damper connected in parallel. The proportional term mechanically represents a spring which is connected in series with the inherent actuator spring. The optimal control parameters are numerically obtained with the ℋ∞ optimisation criterion. The analysis shows that the optimal feedback gain can be practically taken the same as that of the classical integral force feedback controller in the sense that the difference between the resultant control performance is negligible. The numerical study is also experimentally validated. The obtained results are found to correspond well with the theoretical developments.

The Effect Of Sensory-Motor Virtual Reality On Balance In Children With Clinical Down Syndrome

Introduction: Down syndrome affects approximately one in every 800 live births and leads to musculoskeletal disorders and motor skill delays. Children with Down syndrome experience persistent deficits in balance and coordination. Virtual Reality (VR) offers an interactive and immersive approach to therapy and has gained popularity in rehabilitation. This study explores the effect of sensory-motor virtual reality (VR SenMor) on static and dynamic balance in children with clinical Down syndrome.Methods: A randomized controlled trial with a pre and post-test control group design was conducted with 20 children diagnosed with Down syndrome. Treatment group (n = 10) received VR SenMor therapy twice a week for four weeks, while the control group (n = 10) received no treatment. Balance assessments were conducted using the Pediatric Balance Scale (PBS) and Timed Up and Go (TUG) test before and after the intervention.Results: There were no significant differences in age, gender, or BMI between the intervention and control groups. The VR SenMor therapy resulted in significant improvements in the PBS and TUG test scores in the intervention group compared to the control group.Discussion: VR SenMor therapy enhanced balance in children with Down syndrome, with no confounding effects from age and gender. The VR system's sensory integration feedback and neuroplasticity mechanisms contributed to the improvements. The treatment's positive outcomes make it a promising approach for balance training at home.Conclusion: Sensory-motor virtual reality therapy shows promise in enhancing static and dynamic balance in children with clinical Down syndrome.Keywords: sensory-motor virtual reality; down syndrome

Noise‐tolerant matched filter scheme supplemented with neural dynamics algorithm for sea island extraction

AbstractAchieving high‐precision extraction of sea islands from high‐resolution satellite remote sensing images is crucial for effective resource development and sustainable management. Unfortunately, achieving such accuracy for sea island extraction presents significant challenges due to the presence of extensive background interference. A more widely applicable noise‐tolerant matched filter (NTMF) scheme is proposed for sea island extraction based on the MF scheme. The NTMF scheme effectively suppresses the background interference, leading to more accurate and robust sea island extraction. To further enhance the accuracy and robustness of the NTMF scheme, a neural dynamics algorithm is supplemented that adds an error integration feedback term to counter noise interference during internal computer operations in practical applications. Several comparative experiments were conducted on various remote sensing images of sea islands under different noisy working conditions to demonstrate the superiority of the proposed neural dynamics algorithm‐assisted NTMF scheme. These experiments confirm the advantages of using the NTMF scheme for sea island extraction with the assistance of neural dynamics algorithm.

The Effects of Form-Focused Communicative Grammar Instruction on Students’ Speaking Fluency and Their Attitudes Toward Speaking Lessons

Integrating form-focused instruction (FFI) in the communicative language classroom is the most recently used instructional approach today. To draw learners’ attention to grammatical structures, this approach implements different integrative corrective feedback techniques. The current study investigates the effects of FFI integrated with communicative grammar activities on the speaking fluency of students and their attitudes toward speaking lessons. To carry out the study, participants included 11th-grade students divided into two groups: an experimental group and a control group. Four English teachers from Adilo High School also participated in this study - one of whom intervened and three who had scored the students’ speaking fluency based on the given scoring rubrics. The cognitive and behavioral attitudes of the students were examined through before and after questionnaires. Additionally, the study utilized a quasi-experimental research design with pre- and post-tests to examine students speaking fluency. The finding revealed that FFI integrated with communicative grammar instruction enhanced students’ speaking fluency and their cognitive and behavioral attitudes toward speaking lessons. This suggests that High School students benefit from FFI techniques used in combination with information, opinion, and reasoning-gap communicative grammar activities thus it helped them to improve speaking fluency and change their cognitive and behavioral attitude towards speaking lessons.

An identical path tracking control strategy of the tractor-trailer wheeled mobile robot with an off-axle hitching based on a passive steering angle

For a tractor-trailer wheeled mobile robot (TTWMR, for short) with an off-axle hitching, it is challenging for both tractor and trailer to track a desired path due to the insufficient steering capability of the trailer. As such, a passive steering angle is first introduced, which allows the trailer to follow the same path as the leading tractor. In this way, a given motion task can be reduced to the accurate path tracing problem for the tractor. By considering such a passive steering angle, the motion speed relation between two vehicles of the TTWMR with an off-axle hitching is then derived, based on which its kinematics and dynamics equations are established. Thereafter, a proportion integration feedback controller is then developed by combining the curvature tracing method and the directed Lyapunov method, so that both vehicles can move along an identical path. Finally, simulation results indicate the effectiveness and robustness of the resulting control strategy.

A novel order-separated generalized feedforward design for motion control in energy-efficient electrohydraulic system with proportional and integral feedback

Existing feedforward, or FF, controllers are based on differentially flat models. For double-acting single-rod cylinders, more compact than the double-rod ones, flat models could be constructed either under an incompressible-flow assumption for low-pressure, slow-response applications or for a matched valve-cylinder combination. Contrasting the existing models tackling only a single nonlinear aspect like valve leakage, oil compressibility or friction, a novel FF controller, generalized for different types of valve-cylinder-pump combinations, has been developed here. It is based on the highest-order assumption of incompressible flow that sustains the piston motion. An FFPI controller has been implemented in a laboratory setup for displacement tracking against sinusoidal demands up to 9 Hz frequency. The FF parameters has been estimated by minimizing the deviation of simulation prediction from an offline experimental time-varying response. The PI gains have been selected through a stability analysis by extending Routh criteria for linearized time-variant error dynamics. Comparison against a PI-only controller with identical gains has established the energy-saving potential of the FFPI controller both working with the same variable-displacement pump. In comparison to existing nonlinear adaptive controllers, more precise and smoother responses have been obtained over wider frequency range at lower control expenses, admittedly with occasional marginal penalty in the phase variation. The FFPI controller has exhibited the shortest transient and the highest resilience against measurement noise.

Different controllers for suppressing oscillations of a hybrid oscillator via non-perturbative analysis

To arrive at an equivalent linear differential equation, the non-perturbative approach (NPA) is established. The corresponding linear equation is employed for performing the structural analysis. A numerical computation demonstrates a high consistency with the precise frequency. The correlation with the numerical solution explains the reasonableness of the obtained solutions. For additional nonlinear kinds of oscillation, the methodology gives an exact simulation. The stable construction of the prototype is shown in a series of diagrams. Positive position feedback (PPF), integral resonant control (IRC), nonlinear integral positive position feedback (NIPPF), and negative derivative feedback (NDF) are proposed to get rid of the damaging vibration in the system. It is found that the NDF control is more efficient than other controllers for vibration suppression. The theoretical methodology is applied by using the averaging method for getting a perturbed solution. The stability and influence of various parameters of the structure are established at main and 1:1 internal resonance, which is presented as one of the worst resonance cases. Association concerning mathematical solution and computational simulation is achieved.

Active vibration hybrid control strategy based on multi-DOFs piezoelectric platform

With the increasing requirements for vibration isolation in multiple degrees of freedom (multi-DOFs), active control strategy is becoming more meaningful. However, the vibration isolation performance is limited by the time delay of feedback control, and cannot meet higher requirements. Therefore, this paper proposes a multi-DOFs active vibration hybrid control (AVHC) strategy based on a piezoelectric platform. The AVHC integrates the adaptive feedforward control based on the modified recursive least squares (MRLS) algorithm, and the feedback control based on the integral force feedback (IFF) algorithm. To achieve advanced response, the ground-based vibration signal is offset by the MRLS algorithm. To further reduce the coupling of multi-DOFs, the feedback and feedforward coordinates are fused through the matrix transformation, and the signals are linearly superimposed by the AVHC. The experimental results show that the AVHC can further reduce the resonance peaks of the three translational directions ( X/ Y/ Z) compared with the feedback (FB) control. The resonance peaks are reduced from 14.6 dB (FB) to 3.11 dB (AVHC), from 14.56 dB (FB) to 5.14 dB (AVHC), and from 12.44 dB (FB) to 3.78 dB (AVHC) in X/ Y/ Z directions, respectively. The attenuation rates are improved by 73.36%, 66.19%, and 63.10% in X/ Y/ Z directions, respectively.

Composite adaptive control of submarine and parameter identification by integral regressor excitation

In this article, we develop a novel composite adaptive control system for the dive-plane maneuvers and parameter identification of a multi-input multi-output submarine model. The composite adaptive control system consists of (1) an input–output feedback linearizing control law and (2) an identifier formed by gradient algorithm-based two-parameter estimation laws. Unlike the existing adaptive systems for autonomous underwater vehicles and submarines, a novelty of this composite identifier lies in the use of regressor matrix integral feedback for enhancement in parameter excitation. By the Lyapunov analysis, asymptotic convergence of the depth and pitch angle tracking errors is established. Simulation results show precise depth and pitch angle control, estimation of all model parameters, and robustness to random and sinusoidal disturbance inputs.

A Proportional–Integral Feedback Controlled Automatic Flow Chemistry System to Produce On‐Demand AgAu Alloy Nanoboxes

Mixed‐metal nanoparticles present a challenging task for synthesis with high precision and reproducibility due to the complex interplay of compositional and reaction condition factors. The present study demonstrates a highly precise and automated flow chemistry technique for synthesizing AgAu alloy nanoboxes with tailored optical properties. The synthesis process involves a proportional–integral (PI) feedback control mechanism that enables accurate regulation of reaction parameters, such as the flow rate, to achieve the target AgAu nanoboxes having a desired UV–vis absorbance wavelength. The PI control algorithm is built on the first‐order plus dead‐time model, which correlates the flow rate of the precursors with the maximum absorbance peaks of the resultant nanoalloy products. Based on the difference between the real‐time measured UV–vis absorbance wavelength and the target wavelength, the flow rate of the precursor (i.e., reagent concentration) is tuned via an iterative process until the real‐time absorbance wavelength of the AgAu alloy nanoboxes is matched with the target setpoint. The implementation of a PI feedback control mechanism in a flow chemistry system can offer a highly versatile and universal strategy for generating on‐demand complex nanomaterials with significantly enhanced consistency and reliability by mitigating concentration variations and minimizing the need for human intervention.

On slow-flow dynamics, stability charts, and vibration elimination of a self-excited structure utilizing a novel control technique

This work focuses on vibration elimination, bifurcation control, and stability achievement in a harmonically forced self-excited nonlinear oscillator. A novel control technique called the Integral Resonant Positive Position Feedback Controller () has been introduced in this study. The proposed controller is composed of second-order and first-order filters, integrated into the targeted oscillator in nonlinear form. Then, the averaging equations governing the slow-flow dynamics of the coupled systems are deduced. Subsequently, the relevant nonlinear algebraic system, which characterizes the static bifurcation, is obtained. The effectiveness of the controller in eliminating system vibrations, controlling nonlinear bifurcations, and stabilizing the unstable motion is investigated through bifurcation diagrams, two-dimensional stability charts, and numerical simulations of the instantaneous vibrations. The conducted analyses approved that the not only can stabilize the unstable motion of the considered system, but also it can completely eliminate the self-excited vibration regardless of the forcing magnitude and excitation frequencies. Furthermore, a comparative analysis is conducted to evaluate the control performance of the in comparison to previously utilized control techniques for vibration control in self-excited systems. The comparative results demonstrate that the exhibits superior performance in terms of vibration elimination efficiency, bifurcation control, and stability achievement. Finally, numerical validation corroborated our analytical findings, showing alignment with the analytical solution. Moreover, the simulation results demonstrated that the effectively mitigates undesired vibrations, reducing them to zero in a short transient period.

Pedagogic Exploration Into Adapting Automated Writing Evaluation and Peer Review Integrated Feedback Into Large-Sized University Writing Classes

Automated Writing Evaluation (AWE) software has been viewed as a promising tool for assisting writing. This study integrated AWE and its combination with peer review discussion into writing practice in a large college writing class in the Asian context. Adopting a mixed-method approach, this study employed a quantitative questionnaire to investigate how students perceived the integration at different writing stages and a qualitative interview to examine what prompted their quantitative decisions. The results show that the integration of AWE and peer review feedback significantly reinforced the perceived usefulness of AWE at the revision stage, and students with different proficiency levels had notably different attitudes toward AWE. Their writing anxieties intensified as they became increasingly aware of their own weaknesses during the writing process. Therefore, student writing challenges involve not only language proficiency and writing skills but also psychological variables.

Noise properties of adaptation-conferring biochemical control modules

A key goal of synthetic biology is to develop functional biochemical modules with network-independent properties. Antithetic integral feedback (AIF) is a recently developed control module in which two control species perfectly annihilate each other's biological activity. The AIF module confers robust perfect adaptation to the steady-state average level of a controlled intracellular component when subjected to sustained perturbations. Recent work has suggested that such robustness comes at the unavoidable price of increased stochastic fluctuations around average levels. We present theoretical results that support and quantify this trade-off for the commonly analyzed AIF variant in the idealized limit with perfect annihilation. However, we also show that this trade-off is a singular limit of the control module: Even minute deviations from perfect adaptation allow systems to achieve effective noise suppression as long as cells can pay the corresponding energetic cost. We further show that a variant of the AIF control module can achieve significant noise suppression even in the idealized limit with perfect adaptation. This atypical configuration may thus be preferable in synthetic biology applications.

Diya – A universal light illumination platform for multiwell plate cultures

Recent progress in protein engineering has established optogenetics as one of the leading external non-invasive stimulation strategies, with many optogenetic tools being designed for invivo operation. Characterization and optimization of these tools require a high-throughput and versatile light delivery system targeting micro-titer culture volumes. Here, we present a universal light illumination platform- Diya, compatible with a wide range of cell culture plates and dishes. Diya hosts specially designed features ensuring active thermal management, homogeneous illumination, and minimal light bleedthrough. It offers light induction programming via a user-friendly custom-designed GUI. Through extensive characterization experiments with multiple optogenetic tools in diverse model organisms (bacteria, yeast, and human cell lines), we show that Diya maintains viable conditions for cell cultures undergoing light induction. Finally, we demonstrate an optogenetic strategy for invivo biomolecular controller operation. With a custom-designed antithetic integral feedback circuit, we exhibit robust perfect adaptation and light-controlled set-point variation using Diya.

Self-complexification through integral feedback in eusocial paper wasps of various levels of sociality

We investigate how simple physical interactions can generate remarkable diversity in the life history of social agents using data of social wasps, yielding complex scalable task partitioning. We built and analyzed a computational model to investigate how diverse task allocation patterns found in nature can emerge from the same behavioral blueprint. Self-organizing mechanisms of interwoven behavioral feedback loops, task-dependent time delays and simple material flows between interacting individuals yield an emergent homeostatic self-regulation while keeping the global colony performance scalable. Task allocation mechanisms based on implicitly honest signaling via material flows are not only very robust but are also highly evolvable due to their simplicity and reliability. We find that task partitioning has evolved to be scalable and adaptable to life history traits, such as expected colony size or temporal bottlenecks in the available workforce or materials. By tuning solely the total number of agents and a social connectivity-related parameter in the model, our simulations yield the whole range of emergent patterns in task allocation and task fidelity akin to observed field data. Our model suggests that the material exchange (“common stomach mechanism”) found in many paper wasps provides a common functional “core” across these genera, which not only provides self-regulation of the colony, but also provides a scalable mechanism allowing natural selection to yield complex social integration in larger colonies over the course of their evolutionary trajectory.

Robust integral controller design based on composite nonlinear feedback in uncertain systems with constrained inputs and external disturbances

AbstractIn this article, to enhance the transient performances in constrained uncertain systems, a control technique based on linear matrix inequality (LMI) is characterized to the robust integral composite nonlinear feedback (CNF) controller design. To achieve this aim, considering the inputs limitations and the uncertainties, the regulation is transformed into a minimization subjected to several LMIs. Solving an optimization in real‐time, the gains of the controller are calculated. So, the regulation and the disturbance rejection are effectively handled employing the presented control law. Compared with the existing integral methodology, the provided simulations validate the applicability of the robust integral CNF control law in uncertain systems.

An Active Vibration Isolation and Compensation System for Improving Optical Image Quality: Modeling and Experiment.

Optical detection equipment (ODE) is subjected to vibrations that hamper the quality of imaging. In this paper, an active vibration isolation and compensation system (VICS) for the ODE is developed and systematically studied to improve the optical imaging quality. An active vibration isolator for cameras is designed, employing a dual-loop control strategy with position compensation and integral force feedback (IFF) control, and establishing the mapping relationship between vibration and image quality. A performance metric for evaluating images is also proposed. Finally, an experimental platform is constructed to verify its effectiveness. Based on the experimental results, it can be concluded that the proposed VICS effectively isolates vibrations, resulting in a reduction of 13.95 dB in the peak at the natural frequency and an 11.76 Hz widening of the isolation bandwidth compared with the system without it. At the same time, the experiments demonstrate that the image performance metric value increases by 46.03% near the natural frequency.

Artificial intelligence and pelvic fracture diagnosis on X-rays: a preliminary study on performance, workflow integration and radiologists' feedback assessment in a spoke emergency hospital

PurposeThe aim of our study is to evaluate artificial intelligence (AI) support in pelvic fracture diagnosis on X-rays, focusing on performance, workflow integration and radiologists’ feedback in a spoke emergency hospital. Materials and methodsBetween August and November 2021, a total of 235 sites of fracture or suspected fracture were evaluated and enrolled in the prospective study. Radiologist’s specificity, sensibility accuracy, positive and negative predictive values were compared to AI. Cohen's kappa was used to calculate the agreement between AI and radiologist. We also reviewed the AI workflow integration process, focusing on potential issues and assessed radiologists’ opinion on AI via a survey. ResultsThe radiologist performance in accuracy, sensitivity and specificity was better than AI but McNemar test demonstrated no statistically significant difference between AI and radiologist’s performance (p = 0.32). Calculated Cohen’s K of 0.64. ConclusionContrary to expectations, our preliminary results did not prove a real improvement of patient outcome nor in reporting time but demonstrated AI high NPV (94,62%) and non-inferiority to radiologist performance. Moreover, the commercially available AI algorithm used in our study automatically learn from data and so we expect a progressive performance improvement. AI could be considered as a promising tool to rule-out fractures (especially when used as a “second reader”) and to prioritize positive cases, especially in increasing workload scenarios (ED, nightshifts) but further research is needed to evaluate the real impact on the clinical practice.

The development of teacher feedback literacy in situ: EFL writing teachers’ endeavor to human-computer-AWE integral feedback innovation

While recent years have witnessed increasing theoretical and empirical elaboration on the construct of teacher feedback literacy in higher education and second language education, little research has investigated the development of teacher feedback literacy, especially when teachers collaborate in an attempt to improve feedback strategies with technology. To fill this gap, the present study examined two L2 writing teachers taking the initiative to create, update, and implement a human-computer-automatic writing evaluation (AWE) integral feedback platform, and how such a feedback innovation process impacted their feedback literacy development. The analysis of multiple sources of data, including semi-structured interviews, stimulated recalls, class observation, and artifacts, revealed that the two teachers approached the innovation by orchestrating mediating tools, interacting dialogically with social agents, reflecting critically, and crossing boundaries. Through this process, the development of teacher feedback literacy occurred at varying rates across different aspects. Specifically, positive changes were effected in the teachers’ feedback thinking as well as feedback giving and sharing practices. However, the teachers’ feedback literacy in classroom practice did not seem to have generated as salient a positive outcome. Possible reasons are discussed regarding the scope of the feedback innovation and contextual constraints, and implications are offered. The study underscored L2 writing teacher feedback literacy as a developmental phenomenon molded by situated social practice.

A new stable scheme against false data injection attacks in distributed control microgrid

AbstractFalse Data Injection (FDI) attacks can be injected into the communication links of microgrids and result in significant damages. An approach to detect false data injection (FDI) attacks is introduced and a method to maintain the average voltages of buses within an acceptable range is suggested. To this aim, the impacts of FDI are first studied and a detection mechanism is extracted based on the attack effects. Then, multiple local integral feedback is employed to maintain the voltages within a permitted interval. Next, the procedure to return the values to their initial conditions (following the removal of the attack) is addressed. Finally, the proposed methods are simulated by multiple attack scenarios and validated using experimental tests.