Simple Control Research Articles

Intrinsic toe joint stabilization in foot-slip turning motion of musculoskeletal robot with DSP-SLIP model

This paper introduces the foot-slip turning motion by combining a slider-like mechanism with the double-support parallel spring-loaded inverted pendulum model, in which the musculoskeletal robot uses the model to simplify the slip-turning motion with its compliant structure and utilizes the foot muscle to improve its postural stability. The slip-turning motion, characterized by slight movements for swift turning via foot slippage, is advantageous for musculoskeletal robots due to their limited range of movement. The challenge lies in the reduced support area during the motion, which impacts stability. In our previous study, the robot ‘PneuTurn-T’ successfully executed said motion, whereas the details of the turning mechanism were lacking. This study investigated the utilization of leg compliance in the motion and its static postural stability in the landing stance. Experimental results exhibited a leg compression rate derived from the collected data in the early phase of the motion and validated intrinsic toe joint stabilization with foot muscle for passive postural control. The ground reaction force proves the capability to maintain the posture for 130% longer in the foot with plantar intrinsic muscle. Despite structural challenges, this approach shows promise for musculoskeletal robots, highlighting their ability to handle a turning task with simple control.

NMR Spectroscopy as an Alternative Analytical Method for Biopolymers Without Chromophore: Example of Hyaluronic Acid in Dietary Supplements

To respond to the increasing demand for hyaluronic acid (HA) in dietary supplements (DSs) and nutricosmetics marketed for the treatment of osteoarthritis or moistening, it is essential to have an accurate and reliable method for its analysis in the final products. The study aimed to develop and validate alternative method for the quality control of HA in DSs using low-field (LF) and high-field (HF) nuclear magnetic resonance (NMR) spectroscopy at 80 MHz and 600 MHz, respectively. Moreover, chondroitin sulphate (CH), another active ingredient in DSs, can be simultaneously quantified. The 1H-NMR methods have been successfully validated in terms of limit of detection (LOD) and limit of quantitation (LOQ), which were found to be 0.1 mg/mL and 0.2 mg/mL (80 MHz) as well as 0.2 mg/mL and 0.6 mg/mL (600 MHz). Recovery rates were estimated to be between 92 and 120% on both spectrometers; precision including sample preparation was found to be 4.2% and 8.0% for 600 MHz and 80 MHz, respectively. Quantitative results obtained by HF and LF NMR were comparable for 16 DSs with varying matrix. HF NMR experiments at 70 ℃ serve as a simple and efficient quality control tool for HA and CH in multicomponent DSs. Benchtop NMR measurements, upon preceding acid hydrolysis, offer a cost-effective and cryogen-free alternative for analyzing DSs in the absence of CH and paramagnetic matrix components.

Research to Simulate the Ship’s Vibration Regeneration System using a 6-Degree Freedom Gough-Stewart Parallel Robot

This article presents research results on building a model to reproduce ship vibrations based on a Parallel robot with 6 degrees of freedom Gough – Stewart form. Vibration data at the ship’s center of gravity calculated by simulation software will be the input to the model. The regenerative control system uses a simple PID controller to control input trajectory tracking. Simulation results on Matlab/Simulink software have demonstrated the reproduction of ship vibrations within the allowable error.

Bio-Inspired Screwed Conduits from the Microfluidic Rope-Coiling Effect for Microvessels and Bronchioles

Tubular microfibers have recently attracted extensive interest for applications in tissue engineering. However, the fabrication of tubular fibers with intricate hierarchical structures remains a major challenge. Here, we present a novel one-step microfluidic spinning method to generate bio-inspired screwed conduits (BSCs). Based on the microfluidic rope-coiling effect, a viscous hydrogel precursor is first curved into a helix stream in the channel, and then consecutively packed as a hollow structured stream and gelated into a screwed conduit (SC) via ionic and covalent crosslinking. By taking advantage of the excellent fluid-controlling ability of microfluidics, various tubes with diverse structures are fabricated via simple control over fluid velocities and multiple microfluidic device designs. The perfusability and permeability results, as well as the encapsulation and culture of human umbilical vein endothelial cells (HUVECs), human pulmonary alveolar epithelial cells (HPAs), and myogenic cells (C2C12), demonstrate that these SCs have good perfusability and permeability and the ability to induce the formation of functional biostructures. These features support the uniqueness and potential applications of these BSCs as biomimetic blood vessels and bronchiole tissues in combination with tissue microstructures, with likely application possibilities in biomedical engineering.

IoT based Smart Surveillance with Landmine Detection and Alerts

The research uses a Node MCU microcontroller and Internet of Things (IoT) technology to create a robot for handheld applications. The robot has a night vision camera that connects to the internet, allowing it to take photos and videos from a distance, even at night. It also has a metal detector to find landmines and an infrared (IR) sensor to detect obstacles and prevent accidents. These sensors immediately notify and alert users through LCD screens, messages, and buzzers. The research aims to develop a robot with increased accessibility and user friendliness by offering simple manual and operator controls for robotic inspection. The high-definition camera provides clear photos and videos for detailed analysis of any suspects, helping to make informed decisions quickly and improve situational awareness. On detecting a landmine, the robot alerts the user through the email and displays the information on the LCD screen, enhancing the safety at checkpoints. The IR sensor helps the robot avoid obstacles by alerting the user and sounding a buzzer when something is detected at a close distance. This feature allows the robot to navigate complex environments safely. Overall the robot is designed to provide a smart surveillance by offering an immediate threat response to handle the security concerns in various situations.

Robustness of LiDAR-assisted controller towards measurement uncertainty

Many studies have concluded that LiDAR-assisted control can be used to increase annual energy production (AEP) as well as reduce extreme loads and fatigue damage on blades, tower, and main bearing components. However, most studies assume perfect LiDAR measurements and do not consider large measurement uncertainties on LiDAR measurements. In this study we evaluate the potential benefits in terms of fatigue load reduction from using a simple robust feedforward controller. In addition, we evaluate the impact of measurement uncertainties exemplified by a time shift between the expected time the wind hits the rotor and the actual time it hits the rotor as well as a mean wind speed measurement bias. Results shows that fatigue loads can be reduced up to 7% on the tower sections and up to 4% on other main components. However, these results only applies when the LiDAR is assumed to give perfect information about what is hitting the rotor plane. The load reduction degrades with the magnitude of a time shift of the arriving LiDAR wind measurements. A delay up to 2.5 seconds still gives reasonable load reductions. Furthermore, a positive wind speed bias does not affect the performance of the LiDAR-assisted controller, whereas a negative bias significantly deteriorates performance.

Analysis of Power-Maximizing Region 2 Controllers for Wind and Marine Turbines

Wind and marine energy are rapidly growing and complementary technologies that share some techniques for simplified modeling and control, particularly in below-rated flow speeds. A turbine operator has several choices of controller for maximizing power in Region 2. The simple and ubiquitous KΩ2 control law is often effective but limited in its flexibility. Alternative controllers use reference tracking to split the control objectives into a low-bandwidth optimal tip-speed ratio tracking loop to maximize steady-state power and a higher-bandwidth proportional-integral control loop to reject inflow turbulence. Several options exist for identifying the slowly varying optimal set point during operation, based on estimating the inflow velocity or filtering the power or torque signals. This study compares the trade-offs between performance and other design priorities for a few choices of reference-tracking controller in the literature for reference wind and marine turbines. Analysis is performed in the frequency domain using the linearization of each controller, and the impact of turbulent disturbances on the closed-loop system is described. The controllers are simulated in OpenFAST to analyze their performance with higher-order nonlinear turbine dynamics.

Development of a Motion Controller for the Electric Wheelchair of Quadriplegic Patients Using Head Movements Recognition

The robotic wheelchair is designed to allow independent movement for patients with severe musculoskeletal and neuromuscular disorders that interfere with normal wheelchair propulsion by hands. Control of the movement of the wheelchair necessities residual motion of the upper extremity which was not applicable for patients with upper extremity disability as in Quadriplegic patients. Several research efforts have been proposed to help quadriplegic patients independently use the robotic wheelchair. However, the proposed solutions had many problems with accuracy, simplicity, and cost. The current work aims to build an accurate, simple, and low-cost control system for robotic wheelchairs using head movement. The proposed system was based on the use of the MEMs Inertial measurement unit (IMU) to sense the head movement gestures and transfer the gestures into signals to control the wheelchair movements. A new lightweight algorithm for the detection of head gestures was proposed to improve the system’s accuracy. The proposed system has been applied and tested on volunteers. The results revealed that the accuracy of the proposed method in recognizing head movement was 97% on average.

Trajectory compensation based adaptive control (TCAC) for high-precision piezoelectric actuators

Piezoelectric actuator (PEA) has been widely used in micro-systems, due to the advantages of nano-scale precision, rapid response speed, high stiffness, etc. Nevertheless, the intrinsic nonlinearities of PEA, particularly hysteresis, severely deteriorate its positioning and tracking control accuracy. In most existing control algorithms of PEA, the approximate inverse model of hysteresis is developed to compensate for motion error, which requires high modeling accuracy. To avoid the influence of complex modeling procedures and modeling errors on tracking precision, a trajectory compensation-based adaptive control method has been proposed in this paper. Firstly, a simple linear controller is used to establish the closed-loop feedback system and to guarantee the basic tracking performance of the PEA system. And then, the trajectory compensation is designed according to the frequency analysis of the closed-loop control system. Finally, nonlinear adaptive compensation is used to eliminate the residual errors of the above linear frequency domain model. Different from conventional controllers, the proposed method can achieve excellent tracking control performance without any hysteresis model of PEA. The stability and convergence of the proposed method have been theoretically proved. In addition to theoretical guarantees, the proposed method is validated experimentally and demonstrated to achieve the root-mean-square and maximum value of tracking errors to less than 8 nm and 25 nm, respectively, which has a clear accuracy advantage over other methods.

UNICO: an open-source controller optimized for stall-regulated wind turbines

Stall regulation turbines still represent the preferred solution for small wind turbines. In stall-controlled rotors the controller plays a key role but, differently from pitch-based ones, no open-source controller was available to date. The study presents the UNICO (UNIfi research COntroller) controller, which has been specifically developed for variable speed stall-regulated turbines. The controller has been developed in MATLAB® Simulink® and a dynamic link library (.dll) has been generated, which can be coupled with common simulation codes such as OpenFAST and QBlade using a Bladed-style interface. UNICO includes features that are specifically tailored to variable-speed stall-regulated turbines. For below-rated conditions, the controller employs either the commonly used k-ω2 law or a tracking of the optimal tip speed ratio. For above-rated conditions, a PI controller is used to track a user-imposed reference speed. The reference speed is set to decrease linearly with wind speed, providing a safety margin for turbine operation at higher wind speeds. UNICO has been tested on a 50-kW stall-regulated reference turbine. Preliminary results show how the proposed controller can achieve better overall performance in comparison to the simplified control laws implemented in state-of-the-art codes. Additionally, the rotor speed can be controlled in above-rated conditions, providing an increased run away safety margin.

BLDC Motor based Air Dessert Cooler

Abstract: This paper proposes a new position sensorless drive for brushless DC (BLDC) motors.Growing need for high productivity is placing new demands on mechanisms connected with electrical motors. The demand for low costBrushless DC (BLDC) motor has increased in industrial applications. A simple BLDC motor control algorithm forlow cost motor drive applications using general purpose microcontrollers has been created and presented in this paper. Proposed design will allow the user to rotate the motor either clockwise or counter clockwise direction. Dependingon the rotor position the sensor will give response to the controller circuit. Then the controller circuit will fix the direction of current following to the stator. The design controller circuit is also implemented. The overall design consists of microcontroller circuit, logic gates, switching devices (MOSFET/BJT), BLDC motor, sensors.

Robust PWM control scheme for switched-capacitor MLI with leakage current suppression in grid-connected renewable energy application

Typically, parasitic capacitances exist between the ground and the solar panel terminals in grid-connected PV systems. These parasitic capacitances provide a path for a leakage current, which leads to significant safety concerns, observable and seriously hazardous harmonic orders aligned with the injected grid current, and significant safety difficulties. In this research, a robust PWM controlling method that used competently in reducing the level of the leakage current and improving the power quality of a switched-capacitor Multilevel Inverter. This technique creates developed reference signals from the main signal to generate the switching scheme for the converter circuit. Additionally, the suggested control strategy only works with a small number of carrier signals, resulting in a quick system response and a simpler controller algorithm. Likewise, this controlling approach offers a stable way to maintain a constant output voltage in the suggested converter by adjusting the switching capacitors' voltages, which is not possible with traditional control techniques. MATLAB/Simulink is used to simulate the outcomes for both the suggested control approach and the traditional Phase Disposition (PD) PWM control method whereas the leakage current component reduces to 25 % compared to the captured component with the PDPWM. The simulation and the practical results based on the dSPACE-1103 hardware are quite similar.

Investigation of self-excited induction generator for supporting domestic loads and its extension to a microgrid

This study provides a technical and financial analysis for the incorporation of a microgrid structure with a wind energy conversion system for producing electricity. This study’s primary aim is to provide solutions for issues that arise when isolated induction generators are employed with microgrids. A closed-loop smart electronic load controller is used to regulate the loads in the system that are supplied by the generator. A switched variable capacitor bank is used to supply reactive power initially during a voltage dip at varying winds and loads to sustain the voltage profile. Additionally, a simple voltage control loop-based controller for the generator-side converter maintains the voltage at a steady level. Using HOMER software, an economic study of the suggested wind-based microgrid structure is also presented. A laboratory experimental setup is used to support the MATLAB/Simulink study of the proposed method and its control. The findings support the feasibility of implementing the suggested plan in grid-isolated regions for supplying critical loads.

Overview and development of PID control

Proportional integral differential control, referred to as PID control, is one of the earliest developed control methods, which is widely used in industrial process control because of its simple control algorithm, high reliability and good robustness. The classic PID controller is the simplest control system, but the actual control object usually has the characteristics of strong interference, transient uncertainty, nonlinearity, etc, so it is difficult to achieve the ideal control effect with the classic PID controller. In addition, with complex parameter tuning methods, it is often difficult to find an optimal result for the parameters of the classical PID controller. These factors lead to the fact that classical PID control cannot be applied to complex systems and high-performance systems, so people continue to develop PID control methods, introduce new models, and develop fuzzy PID controllers, expert PID controllers, neural network PID controllers, and PID controllers based on genetic algorithms. This paper will review the development history of PID controllers, and introduce fuzzy PID controllers, expert PID controllers, neural network PID controllers, and PID controllers based on genetic algorithms. The research status and future development prospects of these controllers are also prospected.

Estimation of Crosswind Disturbances for a Vehicle by LPV‐MHE and its Application to Disturbance Cancellation

Crosswinds and transverse slopes of the road surface affect the motion of a ground vehicle as disturbances. The objective of this paper is to develop a method for estimating crosswind disturbances and lateral force disturbances caused by transverse slopes of the road surface under the variation of the vehicle speed. Firstly, a dynamical model of a vehicle is described as a Linear Parameter‐Varying (LPV) system in which the value of the coefficient matrices vary with the vehicle velocity. Then, an algorithm to estimate the disturbance is derived based on Moving Horizon Estimation (MHE) and applied to the derived LPV system. Furthermore, a simple control law which counteracts the effects of the disturbances on the lateral velocity and the yaw rate in steady‐state based on the estimates of the disturbances is presented. The effectiveness of the proposed method is demonstrated by a numerical example. © 2024 The Author(s). IEEJ Transactions on Electrical and Electronic Engineering published by Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Voltage regulation in an interleaved circular chain sliding mode controlled multiphase converter

In this article a multiphase synchronous buck converter controlled by a sliding mode control (SMC) in a circular chain control (CCC) configuration is presented. The proposed switching functions with the CCC architecture ensure a robust output voltage regulation when facing changes in the load or the input voltage, while providing current equalization among the phases. The novelty of the work is the simple control structure based on a first order SMC implemented by means of hysteresis-band comparators, requiring no external signals or additional hardware to lead the system to an interleaving operation, obtaining a harmonic cancellation that allows the size reduction not only of the output capacitor but also of the inductors. It is proved that, in the steady state, the switching function exhibits a periodic solution with a period equal to the switching period. Besides, the steady-state switching frequency expression as a function of the hysteresis bandwidth is derived. The work includes the analytical analysis of the proposed solution, a set of numerical simulations and, finally, an experimental validation. The numerical and experimental results confirm the predicted good performance of the proposed control.

Sensory-Motor Loop Adaptation in Boolean Network Robots.

Recent technological advances have made it possible to produce tiny robots equipped with simple sensors and effectors. Micro-robots are particularly suitable for scenarios such as exploration of hostile environments, and emergency intervention, e.g., in areas subject to earthquakes or fires. A crucial desirable feature of such a robot is the capability of adapting to the specific environment in which it has to operate. Given the limited computational capabilities of a micro-robot, this property cannot be achieved by complicated software but it rather should come from the flexibility of simple control mechanisms, such as the sensory-motor loop. In this work, we explore the possibility of equipping simple robots controlled by Boolean networks with the capability of modulating their sensory-motor loop such that their behavior adapts to the incumbent environmental conditions. This study builds upon the cybernetic concept of homeostasis, which is the property of maintaining essential parameters inside vital ranges, and analyzes the performance of adaptive mechanisms intervening in the sensory-motor loop. In particular, we focus on the possibility of maneuvering the robot's effectors such that both their connections to network nodes and environmental features can be adapted. As the actions the robot takes have a feedback effect to its sensors mediated by the environment, this mechanism makes it possible to tune the sensory-motor loop, which, in turn, determines the robot's behavior. We study this general setting in simulation and assess to what extent this mechanism can sustain the homeostasis of the robot. Our results show that controllers made of random Boolean networks in critical and chaotic regimes can be tuned such that their homeostasis in different environments is kept. This outcome is a step towards the design and deployment of controllers for micro-robots able to adapt to different environments.

Photoelectrochemical properties of self-powered corundum-structured Ga2O3 nanorod array/fluorine-doped SnO2 photodetectors modulated by precursor concentrations

Herein, corundum-structured Ga2O3 (α-Ga2O3) nanorod array/fluorine-doped SnO2 (FTO) structures have been fabricated by hydrothermal and thermal annealing processes with different precursor concentrations from 0.01 to 0.06 M. The diameter and length of the nanorod arrays are much larger with increasing precursor concentrations due to more nucleation sites and precursor ions participating in the reaction procedures. The optical bandgap decreases from 4.75 to 4.47 eV because of the tensile stress relieving with increasing the precursor concentrations. Based on self-powered photoelectrochemical (PEC) photodetectors, the peak responsivity is improved from ∼0.33 mA W−1 for 0.06 M to ∼1.51 mA W−1 for 0.02 M. Schottky junctions can be formed in PEC cells. More photogenerated carriers can be produced in wider depletion region. From Mott–Schottky plots, the depletion regions become much wider with decreasing the precursor concentrations. Therefore, the enhance responsivity is owing to the wider depletion regions. Due to the reduced possibility of photogenerated holes captured by traps ascribed from fewer green and yellow luminescence defects, smaller charge transfer resistance, and shorter transportation route, the decay time becomes much faster through decreasing the precursor concentrations. Compared with the other self-powered α-Ga2O3-nanorod-array-based PEC photodetectors, it shows the fastest response time (decay time of 0.005 s/0.026 s) simply modulated by precursor concentrations for the first time without employing complex precursors, seed layers or special device designs. Compared with other high-responsivity monoclinic Ga2O3 (β-Ga2O3) self-powered photodetectors, our devices also show comparable response speed with simple control and design. This work provides the realization of fast-speed self-powered Ga2O3 based solar-blind ultraviolet photodetectors by simple modulation processes and design, which is a significant guidance for their applications in warnings, imaging, computing, communication and logic circuit, in the future.

Fuzzy Control Systems for Power Quality Improvement—A Systematic Review Exploring Their Efficacy and Efficiency

Fuzzy-based control systems have demonstrated a remarkable ability to control nonlinear processes, a characteristic commonly observed in power systems, particularly in the context of power quality enhancement. Despite this, an updated and comprehensive literature review on the applications of fuzzy logic in the domain of power quality control has been lacking. To address this gap, this study critically examines published research on the effective and efficient use of fuzzy logic in resolving quality issues within power systems. Data sources included the Web of Science and academic journal databases, followed by an evaluation of target articles based on predefined criteria. The information was then classified into seven categories, including control system type, features of the fuzzy logic controller, fuzzy logic inference strategy, power quality issue, control device, implementation methodology (efficacy testing), and efficiency improvement. Our study revealed that fuzzy-based control systems have evolved from simple type-1 fuzzy controllers to advanced control systems (type-2 fuzzy and hybrid) capable of effectively addressing complex power quality issues. We believe that the insights gained from this study will be useful to both experienced and inexperienced researchers and industry engineers seeking to leverage fuzzy logic to enhance power quality control.

A Model of Gastric Mucosal pH Regulation: Extending Sensitivity Analysis Using Sobol' Indices to Understand Higher Moments.

Several recent theoretical studies have indicated that a relatively simple secretion control mechanism in the epithelial cells lining the stomach may be responsible for maintaining a neutral (healthy) pH adjacent to the stomach wall, even in the face of enormous electrodiffusive acid transport from the interior of the stomach. Subsequent work used Sobol' Indices (SIs) to quantify the degree to which this secretion mechanism is "self-regulating" i.e. the degree to which the wall pH is held neutral as mathematical parameters vary. However, questions remain regarding the nature of the control that specific parameters exert over the maintenance of a healthy stomach wall pH. Studying the sensitivity of higher moments of the statistical distribution of a model output can provide useful information, for example, how one parameter may skew the distribution towards or away from a physiologically advantageous regime. In this work, we prove a relationship between SIs and the higher moments and show how it can potentially reduce the cost of computing sensitivity of said moments. We define -indices to quantify sensitivity of variance, skewness, and kurtosis to the choice of value of a parameter, and we propose an efficient strategy that uses both SIs and -indices for a more comprehensive sensitivity analysis. Our analysis uncovers a control parameter which governs the "tightness of control" that the secretion mechanism exerts on wall pH. Finally, we discuss how uncertainty in this parameter can be reduced using expert information about higher moments, and speculate about the physiological advantage conferred by this control mechanism.