Feedback Control System Research Articles

Machine learning‐enabled optimization of melt electro‐writing three‐dimensional printing

AbstractMelt electrowriting (MEW) is a solvent‐free (i.e., no volatile chemicals), a high‐resolution three‐dimensional (3D) printing method that enables the fabrication of semi‐flexible structures with rigid polymers. Despite its advantages, the MEW process is sensitive to changes in printing parameters (e.g., voltage, printing pressure, and temperature), which can cause fluid column breakage, jet lag, and/or fiber pulsing, ultimately deteriorating the resolution and printing quality. In spite of the commonly used error‐and‐trial method to determine the most suitable parameters, here, we present a machine learning (ML)‐enabled image analysis‐based method for determining the optimum MEW printing parameters through an easy‐to‐use graphical user interface (GUI). We trained five different ML algorithms using 168 MEW 3D print samples, among which the Gaussian process regression ML model yielded 93% accuracy of the variability in the dependent variable, 0.12329 on root mean square error for the validation set and 0.015201 mean square error in predicting line thickness. Integration of ML with a control feedback loop and MEW can reduce the error‐and‐trial steps prior to the 3D printing process, decreasing the printing time (i.e., increasing the overall throughput of MEW) and material waste (i.e., improving the cost‐effectiveness of MEW). Moreover, embedding a trained ML model with the feedback control system in a GUI facilitates a more straightforward use of ML‐based optimization techniques in the industrial section (i.e., for users with no ML skills).

Phase‐Stable Multidimensional Coherent Spectroscopy Based on Dual‐Comb Interferometry

AbstractMultidimensional coherent spectroscopy (MDCS) is a highly intriguing field for the unique capacities to unravel quantum pathways of microscopic dynamics and discern different dipole–dipole interactions. These capabilities are not simultaneously accessible through any other techniques. The foundation of MDCS lies in the stable phase and accurate time information of the multi‐pulse sequences involved. Achieving the phase stability has traditionally relied on ingenious geometric optical designs and multiple feedback control systems, albeit at the cost of complexity. In this letter, a phase stability scheme for high‐resolution MDCS is proposed by replacing traditional laser sources with two highly coherent frequency combs. By employing dual‐comb interferometry, the phase distribution across a broad spectral range and the time information of all the excitation pulses are precisely measured, even in setups that lack phase stability. In the experiment, a rephasing MDCS of rubidium atoms is obtained by applying this approach, wherein the comb resolution is utilized to differentiate the couplings of hyperfine energy levels. This scheme simplifies the structure of MDCS and holds potential for applications in other MDCS systems involving many‐body interactions and non‐absorptive resonances.

A class of time-optimal feedback control for fractional neutral evolution hemivariational inequalities with fixed delay

ABSTRACT In this paper, we study a class of optimal feedback control for a neutral fractional system with hemivariational inequalities. Initially, we derive some existence results of mild solutions for the system by applying the Marteli's fixed point theorem of multivalued maps, properties of generalized Clarke's subdifferential and semigroup operators. Then, by using the Filippov theorem and the Cesari property, a new set of sufficient conditions are formulated to ensure the existence results of a feasible pair for the feedback control systems. Also, we apply our main results to obtain the optimal feedback control pair. Further, we investigate the time-optimal feedback control for our control system. In the end, an example is given to illustrate our theory.

Simulation study on the slow extraction for the improvement of the beam shill structure at J-PARC Main Ring

J-PARC Main Ring (MR) delivers a slow extracted 30 GeV proton beam to the Hadron Experimental Facility using third-order resonance. One of the critical properties required for the proton beam is the flatness of the time structure of the extracted beam (spill structure). We performed a simple beam simulation of the MR slow beam extraction to investigate the effect of the current ripples of the main magnet power supplies on the beam spill structure. In addition, we investigated in the simulation the effects of the feedback control system on the betatron tune using fast Q magnets and the transverse RF system to improve the spill structure. The simulation qualitatively reproduced the measured spill structures. Now the attempts to optimize their parameters for better spill structure are ongoing.

Micro Linear Ultrasonic Motor With a Hall Sensor-Based Feedback Control System

Micro Linear Ultrasonic Motor With a Hall Sensor-Based Feedback Control System

Describing Function and Event Based Analysis of a General Class of Piecewise Feedback Control Systems

The analysis of nonlinear systems can be greatly improved using computer software. In this work the Sridhar nonlinearity is described, and a new parameterization is given that allows to systematically obtain a large number of the classical piecewise nonlinearities as particular cases. The calculation of limit cycles using the describing function (DF) approach for the case of autonomous nonlinear control systems and an event-based simulation method are presented and compared. Finally, a user-friendly, graphically oriented interactive tool based on Sysquake is presented. In this way the students can easily assimilate some concepts of introductory courses in nonlinear control such as the behavior of piecewise linear systems, stable and unstable limit cycles, event-based simulation and the DF method.

Pole placement with minimum gain and sparse static feedback

The work addresses the issue of developing polar positioning algorithms for linear control systems with despotic thinning constraints on a static feedback matrix. The design of sparse-limiting feedback control systems is considered to be one of the more complex issues, but the issue of defining the sparse feedback matrix, which allows the selection of eigenvalues or, in other words, the placement of poles, has not been fully studied. Algorithms for determining the eigenvalues, i.e., solving the problem of pole placement and finding the optimal solution of the technological process control system are considered in the work. The results of numerical analysis confirmed the effectiveness of these algorithms, which allows them to be used in solving practical problems of synthesizing adaptive control systems for technological objects.

Utilizing Fuzzy Logic in Precision Agriculture: Techniques for Disease Detection and Management

Utilizing Fuzzy Logic in Precision Agriculture: Techniques for Disease Detection and Management

A comparative study on chaos control in a fractional-order Rossler system and its time delayed feedback control system

A comparative study on chaos control in a fractional-order Rossler system and its time delayed feedback control system

On nonlinear multipoint conjugate value problem for feedback control systems in the cone

On nonlinear multipoint conjugate value problem for feedback control systems in the cone

Denge Yetisi ve Sportif Performans İlişkisi

When examining the concept of balance, human posture is governed by a complex neuromuscular system that operates according to a precise order. This system allows rapid adjustments related to gravity during both rest and activity, resulting in a physical adaptation known as balance (Soyuer & İsmailoğulları, 2009). In all sports disciplines, it is crucial for athletes to demonstrate their balance performance, which is considered a motor coordination feature. The human body employs a balance mechanism to prevent falls during variable movements (Winter, 1995). Balance is a condition that requires a complex feedback and feedforward control system, operating through visual, somatosensory, and vestibular receptors (Tjernström et al., 2002). Balance proficiency is associated with factors such as muscle strength, flexibility, proprioception, and coordination (Uluç, 2023, p. 119). Balance is acknowledged as a critical skill encompassing athletes' coordination, stability, and control abilities. The performance of balance holds significant importance across all sports disciplines. In this context, the relationship between balance performance and sports performance is of great significance. The objective of this review is to examine the literature regarding the impact of different parameters and the complex balance system on sports performance, based on studies conducted between 2018 and 2023.

Image processing-based online analysis and feedback control system for droplet dripping process

Droplets find wide application across diverse industries, where maintaining their quality is paramount. Precise control over the substance content within droplets demands non-destructive and online analysis techniques, such as Process Analytical Technology (PAT), often integrated with control strategies. In this context, the present study focuses on the example of controlling droplet quality during the dripping process of pills. Leveraging the dripping and image acquisition systems established in previous research, a novel feedback control system centered on image processing was devised for the quality control of dripping pills. The system was developed and its efficacy was assessed, yielding satisfactory outcomes. The proposed system facilitates real-time monitoring of pill weight through the analysis of droplet images during the dripping process, thereby offering real-time feedback control of pill weight. Importantly, this system holds potential for broader applications beyond the scope of this study.

Single PCB sensor-based output current reproduction for three-phase inverter systems

This study proposes a practical output current measurement system in a three-phase inverter with a single printed circuit board (PCB) Rogowski coil sensor inserted in the bus between the DC-link capacitor and the power semiconductor module. This system demonstrates its advantage over conventional output current sensors, such as the Hall effect current sensors, in terms of the size, weight, operation temperature and cost. The system can be applied to 6-in-1 power modules as it does not require sensors in the inverter phase legs.In our previous works, we have developed a method called “envelope tracking”, which is used in this system as well. This method traces the switching current instead of the output current to reproduce the output current signal in real-time. Envelope tracking successfully reproduced the output current waveform for single phase inverters under certain conditions. However, a large error is observed in the three-phase inverter demonstration under a high switching frequency (narrow pulse) or when the switching of different phases overlap each other. These errors must be completely suppressed to implement the system for feedback control in three-phase inverters.In this study, a new analog basis output current waveform reproduction system is introduced to suppress the above mentioned errors. This system is implemented in a three-phase insulated-gate bipolar transistor (IGBT) inverter and successfully reproduces the output current with a single PCB sensor inserted between a 6-in-1 IGBT power module and DC-link capacitor, operating under a switching frequency of 3.5–7.0 kHz and output current of 6 A with DC-link voltage of 150 V.

Modeling and application of droplet oscillation momentum for elucidating the development of surface roughness in wire-arc additive manufacturing

ABSTRACTIn feedback control systems of wire-arc additive manufacturing (WAAM), timely adjustments before the occurrence of deviations (feedforward control) would reduce excessive requirements on the sensitivity and accuracy of characteristic parameters of control systems. However, the search for characteristic parameters suitable for feedforward control is extremely rare in the WAAM field. Herein, based on ‘mass-spring' theory, a model of droplet oscillation momentum (DOM) is developed to describe the dynamic behavior of a pendant droplet and its influencing mechanism on surface roughness. The model combines the contribution of wire movement to droplet displacement with experimental correction of the spring/damping coefficients. The results show that the predictions of the model are in good agreement with the experimental values, and DOM is quadratically correlated with the surface roughness. Therefore, the model can be expected as a characteristic parameter to elucidate the development of surface-forming quality of WAAM-fabricated components.

Synchronous and Fully Steerable Active Particle Systems for Enhanced Mimicking of Collective Motion in Nature.

The collective motion observed in living active matter, such as fish schools and bird flocks, is characterized by its dynamic and complex nature, involving various moving states and transitions. By tailoring physical interactions or incorporating information exchange capabilities, inanimate active particles can exhibit similar behavior. However, the lack of synchronous and arbitrary control over individual particles hinders their use as a test system for the study of more intricate collective motions in living species. Herein, a novel optical feedback control system that enables the mimicry of collective motion observed in living objects using active particles is proposed. This system allows for the experimental investigation of the velocity alignment, a seminal model of collective motion (known as the Vicsek model), in a microscale perturbed environment with controllable and realistic conditions. The spontaneous formation of different moving states and dynamic transitions between these states is observed. Additionally, the high robustness of the active-particle group at the critical density under the influence of different perturbations is quantitatively validated. These findings support the effectiveness of velocity alignment in real perturbed environments, thereby providing a versatile platform for fundamental studies on collective motion and the development of innovative swarm microrobotics.

Control strategy of a piezoelectric stage based on the parameter-dependent Bouc-Wen model under condition variations

This paper proposed a feedforward-feedback (FF-FB) control strategy for a linear piezoelectric walking stage (LPWS) based on the parameter-dependent Bouc-Wen (PD-BW) model under condition variations. The mathematical model of LPWS is established by linearization, which consists of a linear system and a hysteresis nonlinearity system. The linear dynamics model of LPWS is identified by the swept-sine method, whereas the hysteresis nonlinearity model of LPWS is identified based on the PD-BW model. The feedforward controller based on the inverse PD-BW model can compensate for the inherent hysteresis nonlinearity of LPWS at varying excitation frequency, surrounding temperature, and external load. A proportional plus lead-lag feedback controller is built to reduce feedforward modelling error and improve the output accuracy of LPWS. The sensitivity analysis of the LPWS feedback control system is performed to reduce the effect of disturbance and noise. Experimental results present the feasibility and effectiveness of the proposed FF-FB control strategy to achieve an efficient and accurate positioning performance.

Feedback control system design for force-sensing concentric tube-based surgical robot: Kinematics using Bernstein polynomials

A novel force sensing module integrated into a concentric tube robot (CTR) was proposed for vitreoretinal surgery in our previous work, and this robot was able to provide tip force information to the operating surgeon. However, when the force-sensing module was integrated, the property of the tube changed, and the conventional modeling-based control algorithm proved to be unsuitable for the force-sensing concentric tube robot (FSCTR). In this work, we have proposed a shape optimization algorithm for the FSCTR to prevent snapping issue while providing an adequate workspace. A corollary actuation system was used to control the FSCTR. The forward kinematics of the FSCTR consisted of rigid body motion and shape variation, where the shape variation was determined using Bernstein polynomials. Inverse kinematics was derived using the Newton–Raphson method. A feedback controller was designed to compensate for the error caused by rigid body motion. Several experiments were conducted to evaluate the performance of the proposed control system. The experimental accuracy of the proposed forward kinematics was 0.15 ± 0.16 mm, and this result was superior to that of the torsionally compliant model. The accuracy of the inverse kinematics was 0.55 ± 0.24 mm, and the accuracy of point targeting under feedback control was 0.12 ± 0.05 mm. Overall, the results of this study indicate that the proposed motion control system satisfies the standards required for vitreoretinal surgery.

Performance-Driven Fault Detection for Uncertain Takagi–Sugeno Fuzzy Feedback Control Systems

This paper mainly studies the performance-driven fault detection for general uncertain Takagi-Sugeno fuzzy feedback control systems, where the infinite-horizon quadratic index is introduced to describe the concerned system performance. Different from the existing output-driven fault detection methods, the proposed approach aims to detect the performance degradations induced by faults. For this purpose, the performance index embedded with the information of system dynamics is reformulated for linear feedback control systems with reference inputs. The performance residual, which is adopted as the evaluation function, is derived based on the Bellman equation and further represented into an explainable form. Then, for uncertain linear feedback control systems, the boundaries of the performance residual are analyzed via the linear matrix inequality technique and an advantaged threshold setting scheme is proposed with the aid of randomized algorithm. Concerning the main objective, a novel approximation method which combines the fuzzy blend of local performance indices and the radial basis function neural network is developed to approximate the global performance index for Takagi-Sugeno fuzzy systems. Based on the result in linear case, the performance residual is constructed along the closed-loop system trajectory and the threshold is determined for the fuzzy control systems with reference inputs and model uncertainties. Finally, simulation studies are provided to show the effectiveness of the proposed theoretical results.

The Influence of Service Quality, Product Quality, Price Perception and Location on Visitor Satisfaction

The goal of this study is to ascertain how consumer satisfaction at Lawson Salemba is impacted by product quality, price, and service quality. The consumers of Lawson Salemba make up the population under study. There were 130 responders in total, and a non-probability sampling strategy was employed. We used a survey instrument and survey methodology, and data was gathered. Multiple regression analysis is the data analysis technique employed. The study's findings demonstrate that location, product quality, price perception, and service quality all have a favorable and substantial impact on customer satisfaction. The managerial implications of this research are improving service quality by implementing high service standards and ensuring that each team member understands and implements these standards, assessing pricing strategies, and ensuring that the prices set are in line with customer perceptions of the value of the product or service, implementing a quality control system and monitor customer feedback regularly and analyze geographic and demographic data to assess whether the location can be optimized or whether it is necessary to open a branch in a more strategic location.

Real-world application of a discrete feedback control system for flexible biogas production

Using renewable energy is increasingly prevalent as part of a global effort to safeguard the environment, with a reduction in {mathrm{CO}}_{2} being one of the primary objectives. A biogas plant provides an opportunity to produce green energy, but its profitability prevents it from being utilized more frequently. A suitable response to this economic issue would be flexible biogas production to exploit fluctuating energy prices. Nevertheless, the complex nature of the anaerobic digestion process that proceeds within the biogas plant and the wide range of substrates that may be utilized as the plant’s feeds make it challenging to achieve flexible biogas production truly. Most plant operators will rely on their experience and intuition to run the plant without knowing exactly how much biogas they will produce with the feed substrate. This work combines a system model estimation and feedback controller to provide an intuitive yet precise feedback control system. The system model estimation represents the biogas plant mathematically, and a total of six distinct approaches have been compared and evaluated. A PT1 model most accurately approximated the step-down and the step-up by the time percentage method, with the Akaike Information Criterion as the primary evaluation criterion for selecting the best model. The downward model was controlled by a discrete PI controller modified with the Root Locus Method and an Anti-Windup scheme, and the upward model was controlled by a state space controller. The quality of the controller was evaluated in both simulation and at the actual biogas plant in Grub, and the controller was able to reduce the biogas production rate approaching the setpoint in the expected period. Furthermore, the developed feedback control system is effortless enough to be installed in many biogas plants.