Passive Control Strategy Research Articles

Modeling of Piezo Stack Actuators and Their Application in Active Vibration Control

This paper presents the vibration control of a highly simplified two degree of freedom model of a helicopter. The vibration control study has been performed using both active and passive vibration control schemes. In the case of active vibration control, the feedback mechanism affects the stiffness of the system; whereas in passive vibration control, the absorber mass affects the inertia of the system. The active control is achieved using a combination of piezo stack sensor and actuator mechanism. A finite element model for the piezo stack mechanism has been developed to obtain a relation between deformation, applied/induced potential and externally applied mechanical load. The results of this study indicate that inclusion of sensor and actuator units increases the natural frequency of the system due to increase in stiffness of the system. It is observed that in the case of active vibration control, the frequency response of acceleration of the system is highly sensitive to small variations in the magnitude of gain around its optimum value and insensitive to changes in excitation frequency; whereas in passive vibration control, the frequency response does not exhibit any significant change in the characteristics with respect to the variation in the absorber mass, while it is highly sensitive to changes in operating frequency.

Significance of Arrhenius activation energy and binary chemical reaction in ternary hybrid nanofluid flow over a convectively heated porous curved surface: A passive control strategy

The convective flow of Jeffrey ternary hybrid nanoliquid over a curved stretching sheet, water-based aluminum oxide and graphene nanoparticles and single wall carbon nanotubes had been employed in this work to explore the hydrothermal variation. In the process of modeling the mechanism of mass transfer, activation energy and binary chemical processes are taken into consideration. The expressions of energy and mass are computed with the extra influence of Brownian diffusion and the thermophoresis characteristics. The initial step in evaluating leading equations involves transforming them into dimensionless forms through similarity transformations. To supplement the assessment, a diverse range of graphs and tables are utilized. The exploration and discussion of various parameters and their impact on involved fields are also presented. In ternary hybrid nanoliquids, an increase in thermophoresis and Brownian motion parameters positively impacts heat transfer capacity. The Biot number exhibits a positive influence on heat transport, while the Schmidt number reduces mass transfer. The curvature parameter has a beneficial impact on the heat transmission rate. Furthermore, as the activation energy parameter rises, the mass transport increases, while it decreases as the chemical reaction rate parameter increases.

Multi-input multi-output phononic subsurfaces for passive boundary layer transition delay

This paper documents progress towards developing a passive boundary layer transition delay strategy using a phononic subsurface (PSub). High-order implicit large-eddy simulation (ILES) is used to explore control requirements for boundary layer transition delay in the context of guiding passive flow control strategies. Positive phasing of surface displacement relative to forcing from a Tollmien-Schlichting (T-S) wave is shown to be effective at attenuating instability for the present flow conditions. Although difficult to achieve with a single input system, positive phasing can be realized with a multi-input, multi-output (MIMO) system. To this end, a MIMO PSub was developed and a reduced-order model was coupled with the flow solver. Positive phasing, and therefore a small degree of passive transition delay, was demonstrated on a flat plate boundary layer. Further optimization of subsurface properties and placement of multiple devices are likely to improve controller efficacy.

Implementation of active and passive control strategies for power generation in a solar chimney power plant: A technical evaluation of Manzanares prototype

Nowadays, it is necessary to develop sustainable energy suppliers according to the concerning environmental issues. Solar energy is one of the appropriate solutions. Solar Chimney Power Plant (SCPP) represents a viable form of solar thermal electricity generation technology. Temporal variations in the driving factors of the plant, especially solar radiation, cause significant fluctuations in output power. This study evaluates active and passive control strategies for achieving more stable power generation in SCPP using Fuzzy Logic Control (FLC) and Thermal Energy Storage (TES) systems. The governing equations for performance modeling have been solved by a developed MATLAB code and validated with experimental data from the Manzanares prototype. Using TES reduced output power fluctuations and showed daily electrical energy generation of 331.9, 314.3, and 308.7 kWh for sand, limestone soil, and water-filled bags, respectively. Implementing an active control strategy with the FLC system alone provided a 25 and 30-kW baseload generation in the mid-hours of the day. Finally, integrating the FLC and TES systems in a hybrid control strategy continued a base load power generation of 12 and 16 kW up to 4 h after sunset, utilizing limestone soil and water-filled bags, respectively.

On the Benefits and Limitations of Modulated Damping With Passive Motor Control

Abstract Conventional emulated damping, in which velocity feedback is employed in combination with motor current control to emulate damping, is used in a number of mechatronic applications. As known in the field, although such damping should be strictly passive, several implementation factors render this emulation nonpassive and subject to instability, especially with increasing damping ratios. This paper describes an alternative implementation of emulated damping that employs passive motor control, which does not draw energy from a battery or any other power source. The method is specifically described in the context of a brushless direct-current (BLDC) motor; an unique controller architecture is used along with a particular MOSFET switching scheme which employs only a subset of the standard BLDC motor driver and does not require electronic commutation. This paper employs analytical and experimental means to compare damping control with the described passive motor approach, relative to using a conventional BLDC motor control approach. Stability considerations for each scheme are discussed. Benchtop testing demonstrates the advantage of the passive control scheme in terms of providing smooth behavior, enhancing control robustness, preventing energy leaks, and providing accurate behavior. The special cases of unilateral and asymmetric behaviors (i.e., different damping command for each direction of rotation) are also considered.

Base Vibration Effects on Additive Manufactured Part Quality

Additive Manufacturing (AM) has opened the door for portable and self-sufficient fabrication. However, environments with base vibration degrade part quality during production. This work focuses on investigating and mitigating the effects of base vibration on AM part quality. Factors influencing part quality initiated the approach, followed by experiments on an extrusion-type printer to inspect and minimize vibration effects. Part roughness was used as the part quality metric based on preliminary experimental observations. A modal impact test identified the print bed and print head gantry as vibration-sensitive components at ≈ 40 Hz. These vibration modes were targeted with experiments to evaluate and reduce vibration effects. Vibration originating from machine operation and vertical base vibration were compared. Part quality was impacted by base vibration 600 × more than by machine operation. Part roughness correlated with vertical base vibration intensity as the roughness standard deviation increased over 85%, from 187.71 μ in to 349.01 μ in, for parts printed with base vibration compared to parts printed without. This result indicated base vibration as the primary vibration source that leads to part quality degradation. A passive vibration control scheme was implemented resulting in a 93% reduction in the relative motion between the print head and bed, from 23.71 to 1.75 g/g, and a 16% improvement in part surface roughness, from 1015.60 to 850.39 μ in. This research provides direction for extending AM to harsh operational environments.

Fuzzy Adaptive Passive Control Strategy Design for Upper-Limb End-Effector Rehabilitation Robot.

Robot-assisted rehabilitation therapy has been proven to effectively improve upper-limb motor function in stroke patients. However, most current rehabilitation robotic controllers will provide too much assistance force and focus only on the patient's position tracking performance while ignoring the patient's interactive force situation, resulting in the inability to accurately assess the patient's true motor intention and difficulty stimulating the patient's initiative, thus negatively affecting the patient's rehabilitation outcome. Therefore, this paper proposes a fuzzy adaptive passive (FAP) control strategy based on subjects' task performance and impulse. To ensure the safety of subjects, a passive controller based on the potential field is designed to guide and assist patients in their movements, and the stability of the controller is demonstrated in a passive formalism. Then, using the subject's task performance and impulse as evaluation indicators, fuzzy logic rules were designed and used as an evaluation algorithm to quantitively assess the subject's motor ability and to adaptively modify the stiffness coefficient of the potential field and thus change the magnitude of the assistance force to stimulate the subject's initiative. Through experiments, this control strategy has been shown to not only improve the subject's initiative during the training process and ensure their safety during training but also enhance the subject's motor learning ability.

Research on Fuzzy Active Disturbance Rejection Control of LCL Grid-Connected Inverter Based on Passivity-Based Control in Weak Grid

In response to the problems of impedance variation and rich background harmonics in the weak grid environment of traditional LCL grid-connected inverters, which cause distortion of the grid-connected current and reduce the stability of the entire grid-connected system, this paper proposes a passive fuzzy-active disturbance rejection control strategy. Firstly, passivity-based control (PBC) is introduced into the grid-connected inverter system to ensure the global stability of the entire system. Secondly, in order to solve the problem of difficult selection of inverter-side current, active disturbance rejection control (ADRC) is used to directly track the grid-connected current, avoiding the tracking error of AC signal and suppressing the interference of background harmonics of grid voltage. The combination of fuzzy control and ADRC simplifies the system parameter tuning process, and the FUZZY-ADRC grid-connected current outer loop and PBC inductance current inner loop are combined to form a multi-loop control system. Finally, simulation comparison verifies that the proposed control strategy can effectively suppress the harmonics of grid-connected current, improve the quality of grid-connected current, and enhance the stability of the entire grid-connected system in a weak grid environment.

Frequency-tuned surfaces for passive control of wall-bounded turbulent flow – a resolvent analysis study

The potential of frequency-tuned surfaces as a passive control strategy for reducing drag in wall-bounded turbulent flows is investigated using resolvent analysis. These surfaces are considered to have geometries with impedances that permit transpiration and/or slip at the wall in response to wall pressure and/or shear and are tuned to target the dynamically important structures of wall turbulence. It is shown that wall impedance can suppress the modes resembling the near-wall cycle and the very-large-scale motions and the Reynolds stress contribution of these modes. Suppression of the near-wall cycle requires a more reactive impedance. In addition to these dynamically important modes, the effect of wall impedance across the spectral space is analysed by considering varying mode speeds and wavelengths. It is shown that the materials designed for suppression of the near-wall modes lead to gain reduction over a wide range across the spectral space. Furthermore, a wall with only shear-driven impedance is found to suppress turbulent structures over a wider range in spectral space, leading to an overall turbulent drag reduction. Most importantly, the present analysis shows that the drag-reducing impedance is non-unique and the control performance is not sensitive to variations of the surface impedance within a favourable range. This implies that specific frequency bandwidths can be targeted with periodic material design.

Force-torque (F-T) based multi-drone cooperative transport using fuzzy logic and low-cost and imprecise F-T sensor

This paper presents a novel approach to perform the task of cooperative transportation (CT) by using multiple quadcopter drones. A leader-follower approach is utilized. Considering that the leader drone can be controlled using different means, such as Proportional, Integral, and Derivative (PID) control or remote control by an operator, this paper focuses on designing the control scheme for the follower drone. This paper specifically considers outdoor application of such systems that requires usage of Global Positioning System (GPS) to receive the positional information of the drones. However, GPS has inherent errors of order of magnitude that can destabilize the system. In order to address this major limitation, a Force-Torque Feedback Controller (FT-FC) is proposed to control the follower drone. The FT-FC provides control based on the interaction forces and torques acting at the point of contact between the follower drone and the payload. Using such passive control schemes, drones are thus not required to communicate with each other. Fuzzy Logic (FL) is used to implement the FT-FC. Fuzzy Logic provides effective force-torque coordination between drones, emulates human behavior during CT, and allows use of noisy inexpensive force-torque sensors. This paper presents results from numerical simulations showing the effectiveness of the proposed controller for way-point navigation and complex trajectory tracking. Additionally, the effectiveness of the fuzzy-based FT-FC in terms of handling disturbances is also demonstrated. The proposed FL FT-FC is also experimentally validated for two applications viz. three-dimensional physical Human Drone Interaction (HDI) and CT.

Passive Sliding Mode Control Strategy for Y-type Modular Multilevel Converter Topology in the Unbalanced Power Grid

Passive Sliding Mode Control Strategy for Y-type Modular Multilevel Converter Topology in the Unbalanced Power Grid

Bio-inspired variable-stiffness flaps for hybrid flow control, tuned via reinforcement learning

A bio-inspired, passively deployable flap attached to an airfoil by a torsional spring of fixed stiffness can provide significant lift improvements at post-stall angles of attack. In this work, we describe a hybrid active–passive variant to this purely passive flow control paradigm, where the stiffness of the hinge is actively varied in time to yield passive fluid–structure interaction of greater aerodynamic benefit than the fixed-stiffness case. This hybrid active–passive flow control strategy could potentially be implemented using variable-stiffness actuators with less expense compared with actively prescribing the flap motion. The hinge stiffness is varied via a reinforcement-learning-trained closed-loop feedback controller. A physics-based penalty and a long–short-term training strategy for enabling fast training of the hybrid controller are introduced. The hybrid controller is shown to provide lift improvements as high as 136 % and 85 % with respect to the flapless airfoil and the best fixed-stiffness case, respectively. These lift improvements are achieved due to large-amplitude flap oscillations as the stiffness varies over four orders of magnitude, whose interplay with the flow is analysed in detail.

Bayesian Optimization Based Adaptive Control of Thermoacoustic Instabilities

Thermoacoustics instability is one of the factors that limits the operational range of gas turbines. Both active and passive control strategies have been developed to suppress thermoacoustic instability. Active control strategies can adapt to the gas turbine's operational condition and hence provide a wider effectivity than the passive control strategies. However, it remains a challenge to best optimize the control parameters. This work proposes an adaptive control strategy by using Gaussian Process Regression with a modified Safe-Optimisation (SafeOpt) algorithm. The main benefit of the algorithm is it can safely explore the parameter space and minimize the cost function simultaneously. The performance of the algorithm in suppressing the thermoacoustic instability is experimentally demonstrated by stabilizing a turbulent combustor with loudspeakers actuation.

Hydrodynamic independence and passive control application of twist and flapwise deformations of tidal turbine blades

The load-induced deformations experienced by axial-flow rotor blades can result in significant hydrodynamic impacts on rotor operation. These changes in hydrodynamics are dominated by the flapwise and twist deformation components, affecting blade loading and performance. This work uses blade-resolved computational fluid dynamics simulations to explore the hydrodynamic interactions of coupled flapwise and twist deformations, and their potential for use in passive control strategies. The rotor blades were simulated under parametrically prescribed flapwise-only, twist-only and coupled flapwise–twist deformations. The results show that the hydrodynamic effects are adequately described by blade-element theory for twist deformations regardless of the presence of flapwise deformations, whereas flapwise deformations induce changes in the local lift and drag coefficients that are independent of twist. For moderate blade deflections, the hydrodynamic changes generated by the two deformation components can be approximated to be independent from each other. The observed hydrodynamic independence between the two deformation components is used to explore passive deformation strategies for a tidal rotor. By extrapolating an existing dataset containing CFD simulations of twist-only and flapwise-only deformation cases at different tip-speed ratios, control paths are designed within a tip-speed ratio, flapwise and twist deformation parameter space. These control paths demonstrate passive control strategies as a potential alternative to active pitch control on tidal turbines, showing similar performance and maximum loading, compared with an active pitch strategy, over a full tidal cycle. In particular, it is shown that flapwise deformations have an important role in power capping above rated flow speed.

A passive control strategy of a micropolar hybrid nanofluid flow over a convectively heated flat surface

In this report, the authors have presented a semi-analytical analysis on thermal convective magnetohydrodynamic flow of a water-based micropolar hybrid nanofluid comprising of Ag and CuO nanoparticles over a stagnant point region of a surface. Thermal convection and mass flux conditions are taken in flow problem. Additionally, the impacts of Brownian motion, chemical reaction, thermophoresis, heat source, and viscous dissipation are taken into account. Also, the Cattaneo-Christovo flux model is used to analyze the transportations of heat and mass. The problem formulation is transformed into dimensionless form by means of suitable similarity transformations. The homotopy analysis technique (HAM), which is semi-numerical approach that does not require small or large factors, is applied. The convergence of each profile of the flow functions are demonstrated in pictorial form. The code has been utilized in the MATHEMATICA 12.0 software. The results show that the growing micropolar factor reduces the velocity and micro-rotational distribution. Also, the coefficient of skin friction is a decreasing function of the magnetic factor. The growing magnetic factor upsurges the velocity distribution, where a dual impact of the magnetic factor on microrotation distribution is observed. The heat transfer rate is a reducing function of Eckert number, magnetic, Brownian as well as thermophoretic factors. Mass transportation rate has declined with growth in Brownian and thermophoresis factors.

Effect of a passive control strategy on lean ignition and blowout performance of a gas turbine combustor

In this study, a radial strut is designed in the mainstream channel of a trapped vortex combustor (TVC) to improve the mixing between cavity products and mainstream air. This improves combustion efficiency and uniformity of outlet temperature distribution. However, a certain amount of mainstream flow is entrained into the cavity owing to the blockage of the radial strut; this entrainment deteriorates the ignition and blowout performance. To resolve this problem, a passive control strategy using a vertical jet is proposed to restrain the entrainment of mainstream flow into the cavity. Experimental results indicate that compared with the conventional TVC, the proposed strategy significantly improves the ignition and blowout performance. To gain insight into the experimental results, Reynolds-averaged Navier-Stokes-based simulations with a validation methodology were conducted to simulate the flow field and fuel distribution characteristics of the cavity. The simulation results demonstrate that the passive control strategy can effectively restrain the mainstream air entrained in the cavity. The improved ignition and blowout performance provided by passive control strategy can be attributed to the formation of a desirable flow structure with two vortices and high local fuel equivalence ratio inside the cavity.

Mitigating borehole drill string torsional vibration and shock

This paper provides an analysis of one of the dysfunctions in borehole drill strings, which is torsional vibration. Additionally, an analysis of mitigation through systematic adjustment of the key parameters of Weight on the Bit (WOB) and Rotations per Minute (RPM) is conducted. One of the key forms of dysfunction is undesired vibration and shocks on the drill strings. The vibration and shock experienced by drill strings have a detrimental impact on equipment life, resulting from damage to the drill bit and the drill string components. This paper studies a generalized lumped-parameter model of the drill-string system to provide a fundamental understanding of the torsional stick-slip vibrations during drilling operations. The impact of various parameters such as the weight on the bit, rotational speed, and damping on the severity of vibration, in particular, stick-lip vibration, is analyzed. Various passive, active, and semi-active control strategies to mitigate the torsional vibrations have been studied and implemented with varying degrees of success, subject to continual development. From the simulation, the WOB, the drive torque, and rotational velocity determine the stick-slip onset and severity. This paper focuses on active control of the rotational speed and the weight on the bit by systematic adjustment to eliminate stick-slip while avoiding other undesirable effects and thus achieving optimum performance. Further study will be on multi-stability analysis to define the optimum operation zones and the design of vibration reduction tools and control strategies.

Vernacular Architecture in México: The Blue Corn Research Center in Michoacán

In Mexico, a large part of the population is still engaged in primary activities such as agriculture. That is why government and academic institutions have focused on encouraging the improvement and optimization of the farming of basic grains through research and technology. This work aimed to propose a building based on the Mexican vernacular architecture of Michoacán using local materials. The architectural project used the scientific method of analyzing socio-economic indicators, territory, and cultural conditions. As a result, we got a building that promotes the increase in the production of blue corn and solves part of the student lag in the rural area of Michoacán. The building contemplates open access for people of the surrounding towns through community use. Its design applies passive thermal control strategies. The project is a connection between local agricultural customs and the field of research.Keywords: contemporary

Hydrothermal and mass aspects of MHD non-Darcian convective flows of radiating thixotropic nanofluids nearby a horizontal stretchable surface: Passive control strategy

Numerous rheological examinations attested that many products employed frequently in our daily life exhibit a thixotropic rheological behavior with a shear-thinning tendency (e.g., toothpaste, hair gels, ketchup, gypsum, and paints). Motivated by the importance of nanofluids in the thermal and mass transfer processes and their rheological trends, this article aimed to analyze convective boundary layer flows of radiating thixotropic nanofluids over a horizontal stretching surface by considering the retardational influences of Darcy-Forchheimer and Lorentz forces and invoking the effective contribution of Brownian and thermophoresis diffusions in the energy and concentration equations. By adopting the boundary layer approximations along with the zero mass flux and convective conditions, the conservation equations of the present non-homogeneous nanofluid flow model are derived mathematically in the form of partial differential equations (PDEs) based on Buongiorno's approach. After converting the leading PDEs into a set of nonlinear coupled ordinary differential equations (ODEs) via feasible local similarity alterations, the resulting highly nonlinear system of governing ODEs is then solved numerically using an efficient differential quadrature algorithm. As findings, it is found that the thixotropy feature reinforces the nanofluid motion. Besides, the significant impact of the radiative term is noticed in the heat flux rate. In contrast, the induced Darcy-Forchhemier and Lorentz forces impact unfavorably on the nanofluid flow and consequently alter the intensity of drag forces. Further results are provided also graphically and tabularly.

A semi-active control system in coupled buildings with base-isolation and magnetorheological dampers using an adaptive neuro-fuzzy inference system

Connecting two buildings has been proved as an effective method of structural control for alleviating seismic responses. Researchers have proposed that two adjacent buildings through supplemental energy dissipating devices to mitigate the buildings’ responses. Numerous researchers have proposed various methods: active, passive, and semi-active control strategies. In Japan, some applications of coupled buildings control have been successfully implemented by utilizing passive and active control technology. Magnetorheological (MR) dampers have been identified as semi-active devices that can be used to reduce the vibration of the seismic structures during various types of ground motions. They can offer the adaptability of active devices, stability, and reliability of passive devices. Nevertheless, one of the difficulties in application of the MR dampers is the development of the appropriate control algorithms. Accordingly, this study presents the implementation of the adaptive neuro-fuzzy inference system (ANFIS) controller for earthquake hazard mitigation under coupled buildings control system with base-isolated building connecting to the free wall by MR dampers. The ANFIS whose training data is based on the Linear Quadratic Regulator (LQR) method is conducted to modify the parameters of the fuzzy logic controller and optimize the fuzzy rules. The performance of MR dampers is evaluated under seismic response. It is compared under four methods, including passive-off, passive-on, and two semi-active control strategies: ANFIS and LQR. Besides, various types of feedback of the ANFIS operated as two-input single output feedback system are investigated to assess the performance of the developed control scheme for structural vibration control. The numerical simulation results show that the proposed semi-active control system consisting of coupled buildings system and MR dampers by utilizing ANFIS can be effective in mitigating seismic responses of structures.