Dynamic Response Control Research Articles

Study on the Influence of Lightweight Mechanical Structure on UAV Dynamic Response Characteristics and Control Strategy Optimization

Study on the Influence of Lightweight Mechanical Structure on UAV Dynamic Response Characteristics and Control Strategy Optimization

Control of dynamic orbital response in ferromagnets via crystal symmetry

Control of dynamic orbital response in ferromagnets via crystal symmetry

Investigation on vibration control of TetraSpar floating offshore wind turbine

The stability of offshore wind turbines during operation is crucial, and as an emerging technology, the TetraSpar floating offshore wind turbine demonstrates commendable stability. Moreover, it can effectively reduce the levelized cost of energy (LCOE) in production and installation. However, There is relatively scarce research on its dynamic response and reliability under complex ocean conditions. To reduce the vibration response of floating offshore wind turbines in complex marine environments and improve the stability of the turbines, it is necessary to establish a fully coupled dynamic model to study the multi-field coupled dynamic response and vibration control of the turbines. In light of this, this paper establishes a multi-physical field coupled dynamic model for TetraSpar floating offshore wind turbine through an F2A coupling framework, integrating aerodynamics, servo-elasticity, hydrodynamics, and mooring dynamics. The study analyzes the vibration suppression effects of different Tuned Mass Dampers (TMDs) on the wind turbine system. Using the two main response frequencies, 0.0367Hz and 0.57Hz, in the front and rear directions of the wind turbine as the tuning frequencies for TMD. The best vibration reduction effect was achieved by comparing multiple sets of TMD with different parameters. Analysis shows that TMD can significantly reduce the standard deviation of bending moment and tension of steel bars before and after tower foundation, with maximum values of 38.76% and 73.02%, respectively. At the same time, TMDs also impose a burden on wind turbines, such as a maximum increase of 2.23% in the average values of tower base bending moment, platform pitch, and tower top longitudinal displacement, which also slightly increase under extreme sea conditions. However, compared to the significant vibration suppression effect of TMD, it can be ignored.

Dynamic response and roughness control of surface materials on TC4 titanium alloy subjected to laser shock wave planishing

Abstract In this study, ABAQUS was used to predict the dynamic response of surface materials on TC4 titanium alloy during laser shock wave planishing (LSWP). The experiments were conducted to evaluate the simulations. The results indicate that during the initial stage of LSWP, the contact status between the contact foil and the micro-protrusion changes from the one-dimensional stress state to the one-dimensional strain state. This causes the high-amplitude tensile residual stress to converge at the center of the flattened micro-protrusion surface. When treating specimens with high surface roughness, the application of a thin contact foil can significantly lower the height of micro-protrusions and lift the bottom of micro-depressions. This improves the plastic flow of micro-protrusions and prevents the convergence of tensile residual stress. Using a thick contact foil can help extend the pressure pulse duration and prevent the overall surface profile subsidence when treating specimens with lower surface roughness. The outcomes of the experiment and the simulation agree rather well. Additionally, a thick contact foil can reduce the build-up of tensile residual stress by reducing the contact pressure.

Aliasing Suppression Method for a Three-Phase Grid-Connected Photovoltaic Inverter Based on Multi-Sampling and Mean Filtering

In order to reduce the sampling delay and improve bandwidth, sability margin, and the robustness of the active damping in LCL-filtered grid-connected inverters, real-time sampling provides a convenient method. However, aliasing is easily introduced in the control loop because of high-frequency switching harmonics, resulting in a rise in low-order harmonics. To address the challenge of aliasing under real-time sampling, a new method based on multisampling and mean filtering is proposed by combining the proposed harmonic detection and control methods in this paper. This method works by sampling and controlling the fundamental current and selective subharmonic currents separately. The fundamental current control loop without any additional filters maintains real-time sampling, while multisampling and mean filters are applied to the harmonic current control loop. The proposed control method can not only improve the dynamic response performance and control stability of the system but also effectively suppress the selective low-order current harmonics and the aliasing of sampling. Finally, the correctness of the proposed sampling scheme and control strategy is verified by the simulation based on R2018b, MathWorks, Natick, MA, USA and an experimental prototype of a three-phase grid-connected photovoltaic inverter rated at 230 V/50 Hz/40 kW.

Experimental modeling of dynamic response and speed control of a DC motor using an electronic prototyping board

The modeling and simulation of dynamic systems has become important today due to the strict performance criteria that industrial automation and control systems require in the era of Industry 4.0. This paper presents a study based on experimental modeling of the dynamic response of a DC motor in order to control its speed using a PID controller, with the aim of maintaining the motor's constant rotation speed using the three control actions: proportional, integral and derivative. Thus, the practical implementation is carried out using an Arduino, where speed and voltage data from the open loop system is collected and inserted into the Matlab® tool, so that it is organized and used to generate the respective transfer function of the developed system and therefore control the motor's revolutions per minute.

Design and implementation of a 2-DOF 5R parallel mechanism with a coaxial-driven layout

In order to expand and improve the reachable workspace of planar parallel manipulators, a 2-DOF 5R parallel mechanism with a coaxial-driven layout is proposed. The configuration analysis and structural design are carried out, and the kinematic model is presented to conduct simulation analysis. The results indicate that the layout with the axes of the two driving devices overlapping has a larger workspace and a more compact structure. Meanwhile, a closed-loop PID control system is established to evaluate the accuracy of the proposed mechanism and analyse the kinematic error under different gain parameters. Simulation results indicate that the kinematic performance of the mechanism has improved. The control system is constructed based on using a motion control card as the primary control component and two servo motors as the drive device. Additionally, gain values are adjusted by the driver to reduce the deviation of the servo motors. Finally, the design of the prototype is deployed, and the experiment proved that the 2-DOF 5R planar parallel mechanism (PPM) with a coaxial-driven layout has the advantages of a large workspace, fast dynamic response, high stiffness, and easy control. The design of the 2-DOF 5R PPM solves the problem of single operation and high repeatability, which is increasingly utilized in the fields of electronics, food, daily chemicals, and pharmaceuticals.

Active vibration control of functionally graded material plates integrated with piezoelectric layers using new Q9ɤ approach

Abstract A new efficient approach has been developed to simulate the free vibration, static, dynamic response and active control of functionally graded material (FGM) plates with integrated piezoelectric layers. This approach reinforces the standard first-order shear deformation theory by introducing a novel shear strain fields, alleviating the problem of shear locking, especially in the analysis of thin structures. These new fields accurately predict the shear strain fields, satisfying both compatibility and equilibrium equations while requiring less mesh refinement. Furthermore, this current approach provides higher performance and precision in analysing FGM structures. Additionally, a feedback control system has been implemented using either total piezoelectric layers or partial covering (patch) as actuators and sensors in both static bending control and dynamic vibration control analysis. The present work strengthens the basic techniques for further research in finite element analysis across a broader spectrum of materials and applications.

Harmonic Injection Control of Permanent Magnet Synchronous Motor Based on Fading Memory Kalman Filtering

In order to reduce the harm of harmonic disturbances of the permanent magnet synchronous motor (PMSM) control system to the drive and improve the accuracy of the control system, a harmonic injection control method based on asymptotic fading memory Kalman filtering is proposed. Compared with the traditional harmonic injection method, this method reduces the torque pulsation of the PMSM, converges faster, and realizes fast stabilization of the control system. In order to improve the control accuracy of the system, extended Kalman filtering is used to estimate the mechanical angular velocity and optimize the harmonic extraction process to reduce the interference of noise signals in the extraction process. At the same time, a fading memory factor is introduced to replace the fixed gain in the Kalman filter, which can correct the system error and effectively prevent the filtering dispersion, thus enhancing the system’s stability. Finally, the system is simulated and experimentally analyzed, and the results show that the method can improve the dynamic response speed, stability, and control accuracy of the system compared with the traditional harmonic injection method.

Development of a dynamic demand response quantification and control framework for fan-coil air-conditioning systems based on prediction models

The air-conditioning demand response has gradually become an effective approach to reduce peak load of the national grid. However, with the increasing penetration of renewable energy generation sources, static performance evaluation of demand response that only fits one certain scenario cannot meet the demandsofthe times. To address this issue, a novel dynamic demand response quantification and control framework was built based on the secondary development of building energy simulation software and multilayer perceptron algorithm. In this framework, the demand response evaluation method can be used for different global temperature adjustment strategies under different external disturbances and internal loads, and the dynamic demand response control method could be further adopted for load reduction prediction and setpoint adjustment recommendation. The performance prediction model based on artificial neural network can predict the maximum load shedding during demand response period with an average absolute percentage error of 15 %, and the prediction error of load shedding intensity is ± 1 W/m2 for over 80 % of samples. Besides, the setpoint adjustment prediction model achieved an average absolute percentage error of 3 % while its prediction error is ± 0.25 °C for over 99 % of samples. The results prove that this research can provide reasonable suggestions for customers and load aggregators to achieve accurate control of setpoint adjustment in dynamic demand response conditions.

Control of dynamic response of the functionally graded smart sandwich beam coupled variable Kelvin–Voigt–Pasternak's model

Navier’s theoretical solution of the dynamic responses of a rectangular smart beam embedded in a variable viscoelastic foundation is presented by applying a higher-order shear deformation theory. The theory presents a valid representation of the transverse shearing strains; therefore, the shear correction factors are not needed. The elastic part of the foundation is assumed as a Winkler-Pasternak medium considering a variation in Winkler’s layer along a structure side; however, the shear layer stiffness is assumed to be constant. The constant feedback gain control is employed to control vibration of the studied system. Some numerical examples are introduced to investigate the dynamic responses of the system with full illustrations of the different geometrical parameters variation.

Seismic Response Control of a Nonlinear Tall Building Under Mainshock–Aftershock Sequences Using Semi-Active Tuned Mass Damper

Under the excitation of strong mainshock (MS), the structure will enter the nonlinear stage, whose hysteretic characteristic can be well-simulated by the Bouc–Wen (BW) model. The accompanying aftershock (AS) may increase structural damage and cause the safety problem, therefore, the advanced structural control technology is worthy of being applied to nonlinear structure under MS–AS sequences. The tuned mass damper (TMD) is a popular vibrational absorber, however, it is sensitive to the frequency deviation and may lose its effect for nonlinear dynamic response control in this issue. To protect the nonlinear tall building under MS–AS sequences effectively, a semi-active TMD (STMD) is investigated in this study, which can vary its frequency and damping in real time simultaneously. It can adapt to structural nonlinear behavior in each time segment through varying its stiffness according to the wavelet transform (WT) based algorithm, and meanwhile, enhance the energy dissipation through switching its damping coefficient in real time. A 10-story nonlinear tall building is proposed as a case study and for comparison, a passive TMD (PTMD) is used. Nine MS–AS sequences are elected and nonlinear structural control performance of STMD is highlighted. Results show that STMD can control structural displacement responses and base shear effectively and performs better than PTMD in reducing the plastic development of the structure as well. Further, energy analysis is proposed and it is verified that STMD has an excellent effect in decreasing the structural input energy from MS–AS sequences and dissipating more energy than PTMD. Especially, it is found that a strong AS may cause a larger response to the nonlinear structure than MS, while the nonlinear control effect of STMD is still significant in that case.

A dynamic demand response control strategy for isolated microgrid with primary frequency regulation

Electric water heaters (EWHs) are considered as suitable devices for demand response (DR) load control and can be aggregated to participate in primary frequency regulation services for microgrids. However, achieving accurate frequency control of the microgrid through the load response of EWHs while reducing frequency rebound remains a challenge. This paper proposes a dynamic DR load control strategy for primary frequency regulation in microgrids that utilizes EWHs as responsive loads. First, an aggregated model is developed to aggregate EWH clusters based on their physical characteristics. Then, the coefficients of the local frequency curve equation are obtained using the least squares method to predict the nadir of frequency fluctuations. The maximum frequency deviation is calculated based on the nadir of the frequency. Furthermore, an EWH cluster switch control strategy is established based on the EWH temperature and the maximum frequency deviation to determine the switching sequence of EWHs. The simulation results point out that the control algorithm proposed in this study is capable of accurately regulating the frequency of the microgrid within the aggregated capacity range of the EWHs while also the user’s comfort is almost unaffected.

An adaptive virtual capacitive droop for hybrid energy storage system in DC microgrid

Hybrid energy storage system (HESS) is an integral part of DC microgrid as it improves power quality and helps maintain balance between energy supply and demand. The battery and supercapacitor of HESS differ in terms of power density and dynamic response and appropriate control strategies are required to share power among these storage elements. This paper presents an adaptive virtual capacitive droop for supercapacitor in HESS. A switched-controlled capacitor (SCC) is used in series with a supercapacitor to change capacitance droop coefficient which affects the power absorbed and released by the storage element. The SCC control uses state of charge (SoC) balancing mechanism to improve charge profile by reducing the peak and settling time. Moreover, SCC is fully soft switched to reduce switching losses. A detailed design of controller is discussed for HESS. Compared to the conventional supercapacitor control where the SoC balancing is ensured in secondary control, the proposed scheme improves SoC profile of supercapacitor and ensures that it rapidly contributes power during transients of the microgrid. Simulations performed in PSCAD/EMTDC highlight the superior performance of this control over the conventional scheme.

A unified dynamic analysis method for kilometre-scale ultra large spacecraft based on dynamic stiffness method

Ultra-kilometre and super-flexible spacecraft are the important development trends in the future. Classical multi-body dynamics and structural dynamics analysis theory have some limitations in dynamic modelling and solution of large deformation structures. In this paper, an improved dynamic stiffness method (DSM) is proposed to deal with the dynamical modelling and solution of ultra-kilometre spacecraft. The method retains the high accuracy and efficiency of the original DSM in dealing with continuous dynamical systems and breaks through the limitations of the original method in dealing with large deformation structures by introducing equivalent linearization techniques. Results show that the modal frequencies and mode shapes in this paper agree well with finite element solutions, and the maximum deviation is less than 1%; Besides, with the increase of spacecraft length, the structure has entered the nonlinear stage from the linear stage, the fundamental frequency of the structure will be lower than 0.001Hz, and the influence of structure length, density, and the mass of additional cabins on natural frequencies is less significant than that in linear stage. The proposed dynamic analysis framework can be further employed in the dynamic response and vibration control problems of super large spacecraft.

Effective tuned mass damper system for RC tall chimney dynamic wind response control

Tall chimneys have become necessary due to growing industries and changing environmental norms. Chimneys are tall and slender structures and thus they are sensitive towards wind loads. Thus, it becomes necessary to analyze their performance along both the direction i.e. along the wind and across the wind accurately, and to improve their performance by providing suitable measures. Now a days, Tuned Mass Dampers (TMDs) are provided to improve the performance of structures against dynamic loadings However, there are very few reported studies on the effect of TMDs on wind response control of tall chimneys. Hence, it is important to paper the use of different TMD systems and their performance in chimneys. Two RC chimneys of height of 200 m and 220 m of varying thickness are considered for dynamic wind paper using CFD in ANSYS. Modal response of chimney without and with TMD are also studied. The spring mass analogy is used for the connection of chimney and Tuned Mass Dampers. Gust Factor Method as per IS 875 (III) 2015 and IS 4992-1992, for along and across wind load calculation has been studied. Excel Programme file also prepared for the analysis of wind loads using IS codes. Three TMD systems are considered viz. Single Tuned Mass Damper system (s-TMD) and Multiple Tuned Mass Damper system (m-TMD-1 and m-TMD-2).The analysis results of TMD system are compared with the results of without TMD system. The results are compared on the basis of peak displacements of chimney. It has been found that Multiple TMD systems are more effective than Single TMD system. The reduction in deflection of about 25–30% is observed for m-TMD systems.

Two-Degree-of-Freedom Active Disturbance Rejection Current Control for Permanent Magnet Synchronous Motors

In the control of permanent magnet synchronous motors, the active disturbance rejection control (ADRC) has attracted considerable attention due to its intrinsic ability for disturbance rejection. However, the existing ADRC methods have the problem of coupling the reference tracking performance and disturbance suppression performance. To simultaneously improve the current control's dynamic response speed and steady-state control accuracy, a two-degree-of-freedom ADRC current control method based on the improved extended state observer (IESO) is proposed in this article. First, the designed IESO cancels the error correction term in the observed current update law to realize the complete decoupling of the reference tracking performance and disturbance suppression performance. Under the decoupling structure, the observed disturbance update law of the IESO is designed as a proportional-integral-repetitive control structure to suppress periodic and aperiodic disturbances. Then, the system stability is proved by analyzing the distribution of characteristic roots, and a two-step parameter tuning guideline of the IESO is provided. The proposed method realizes the complete decoupling of the reference tracking performance and disturbance suppression performance, reducing the complexity of the controller parameter selection and facilitating the realization of the high-performance current control. Finally, the effectiveness of the proposed method is validated by experimental results.

Dynamic Response Control of Stiffened Plate with Hole in Stiffener: A Novel Concept of Additional Open Branched Stiffeners

Modern day structures have found diverse applications of stiffened plates in civil, mechanical, aerospace, marine and offshore engineering. The stiffeners, mainly in the form of beams in these stiffened plates are often exposed to unfavourable environmental and service loads, inducing localized damage to the stiffeners. Sometimes, holes are deliberately made on the stiffeners for passing service pipes, cables etc. Both of the events cause localised loss of stiffness, finally affecting the global dynamic performances. One of the practised techniques to recover the lost stiffness and to safeguard the damaged site is to introduce enclosed prismatic stiffeners around the hole. However, this often fails to critically readjust the localised stiffness loss. A constructive alternate to alleviate such situation, is to provide open branched configurations of additional stiffeners within the near vicinity of the damage. The present research work deals with the demonstration of the suitability of the above solution through numerical modelling of dynamic behaviour of a rectangular isotropic stiffened plate with a central longitudinal stiffener using finite element software ANSYS. The damage, represented equivalently as a circular cut-out in the stiffener, is considered to be located arbitrarily. Free vibration characteristics viz. natural frequencies and mode shapes of the plate in undamaged and damaged conditions have been determined by solving eigenvalue problem employing Block Lanczos algorithm. Various configurations of open-branched stiffeners around the circular cut-out, placed at specified locations have been explored. The sensitivities of relevant geometric parameters, such as the distance of the branching from the damage site, orientations of the branching etc. indicate that it is possible to design a system of open branched stiffeners around a damaged site of a stiffener to keep the overall dynamic responses practically unchanged. Such idea of branched stiffener is novel and has potential practical applications towards damage mitigation of various engineering infrastructures.

Direct torque control of non-salient pole AFPMSMs with SVPWM inverter

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One-Cycle Control for Pulse Power Generator in Electrical-Discharge-Machining

Due to a short-time gap breakdown in electrical discharge machining (EDM), a high dynamic response and flexible discharge current control ability are required for a pulse power generator. Therefore, a one-cycle control(OCC) of output current for a buck-type EDM pulse power generator is proposed. Considering the inductor current operating state, a full-range OCC current control is presented, and the Taylor expansion method is used for the duty cycle calculation. A duty cycle optimization strategy is proposed for transient states. Based on the small signal modeling, the dynamic response ability of the system is analyzed. The discharge current can switch from many transient states to a steady state in a few switching cycles without a current overshoot, and follow the average current reference well in the steady state.