Simple Design Procedure Research Articles

A computationally efficient approach for robust gain-scheduled output-feedback LQR design for large-scale systems

This paper proposes a novel and simple control design procedure for sub-optimal robust gain-scheduled (GS) output-feedback linear quadratic regulator (LQR) design for large-scale uncertain linear parameter-varying (LPV) systems. First, we introduce a simple and practical technique to convexify the controller design problem in the scheduled parameters. Then, we propose a computationally efficient iterative Newton-based approach for gain-scheduled output-feedback LQR design. Next, we propose a simple modification to the proposed algorithm to design robust GS controllers. Finally, the proposed algorithm is applied for air management and fueling strategy of diesel engines, where the designed robust GS proportional-integral-derivative (PID) controller is validated on a benchmark model using real-world road profile data.

Design of an Intrinsically Safe Series-Series Compensation WPT System for Automotive LiDAR

The earliest and simplest impedance compensation technique used in inductive wireless power transfer (WPT) design is the series-series (SS) compensation circuit, which uses capacitors in series with both primary and secondary coils of an air-gapped transformer. Despite of its simplicity at the resonant condition, this configuration exhibits a major sensitivity to variations of the load attached to the secondary, especially when higher coupling coefficients are used in the design. In the extreme situation that the secondary coil is left at open circuit, the current at the primary coil may increase above the safety limits for either the power converter driving the primary coil or the components in the primary circuit, including the coil itself. An approach often used to minimize this problem is detuning, but this also reduces the electrical efficiency of the power transfer. In low power, fixed-distance stationary WPT, a fair trade-off between efficiency and safety must be verified. This paper aims to consolidate a simple design procedure for such a SS-compensation, exemplifying its use in the prototype of a WPT system for automotive light detection and ranging (LiDAR) equipment. The guidelines herein provided should equally apply to other low power applications.

Compact reconfigurable triple‐mode triple‐band substrate integrated waveguide bandpass filter

In this study, a reconfigurable triple-band triple-mode substrate integrated waveguide filter is designed and fabricated in the C-band spectrum. A novel and simplified design procedure based on analytical equations is proposed. The filter design also benefits from a reconfigurable structure, using metallic via holes as perturbation, allowing wide-band selectivity of the C-band spectrum (from 4.4 to 6.9 GHz). Moreover, the filter benefits from a magnetic coupling solution between the resonators, which only couples the first three modes and rejects the next resonating modes. Therefore, a large bandgap in the spectrum is achieved. The proposed structure is fabricated and measured, and a high similarity between the simulation and fabrication is observed. The measured results show that the first band can be tuned in the frequency range of 4.4 to 7, the second band can be tuned in the range 5.8 to 7.7 GHz, and the third band from 5.8 to 7.7 GHz. The insertion loss 1.5 to 2.5 dB, 2 to 3 dB, and 2.5 to 3.5 dB for the first, second, and third bands, respectively.

Robust Backstepping Sliding Mode Control with L2-Gain Performance for Reference Input Wheel Slip Tracking of Vehicle

The wheel slip control is the basis of active safety control systems and intelligent driver assistance systems. This paper presents a new robust backstepping sliding mode controller for reference input wheel slip tracking based on the single-corner model combined with the actuator dynamics. The proposed controller is realized by combining backstepping method, which has the merits of simplified and flexible design procedure, with sliding mode control, which has robustness against system uncertainty and external disturbance. Moreover, the closed-loop wheel dynamic system is L2-gain stable by Lyapunov-based method, and the simulation results show that the proposed controller has better performance.

Verified and validated design curves and strength reduction factors for post-tensioned composite steel-timber stiffened wall systems

Viability of timber-based solutions for projects is often limited by lengthy modelling and preliminary design when compared to traditional systems such as precast concrete. However, sustainability principles are becoming more prevalent in construction with increasing demands for mid-rise buildings constructed through automated prefabrication via Design for Manufacturing and Assembly (DfMA) techniques. Considering this, this paper introduces and presents design curves for Post-Tensioned (PT) Composite Steel-Timber stiffened wall systems under axial loading. Notably material efficient, they consist of a stiffened engineered timber panel, having half the typical minimum thickness of Cross-Laminated Timber (CLT). Composite action is gained through integrally stiffening the panel with timber studs and steel Square Hollow Sections (SHS), which house a PT rod. The post-tensioning facilitates vertical panel to panel connections for quick on-site assembly, permanent tie-down and self-centering rocking mechanism functionality. A full-scale experimental testing program was conducted in conjunction with analytically verified and validated finite element models. Parametric changes include: level of post-tensioning, number of stiffeners, thickness of panel, height of the wall and applied load. Highly versatile yet simple design curves have been developed from an exhaustive set of incremental results. In addition, a strength reduction factor capturing the effects caused by post-tensioning is proposed. With these, a simple design procedure has been outlined for quick feasibility analysis and preliminary design. That is, for a desired load capacity and level of post-tensioning, the optimal system configurations is given. Likewise, for a chosen configuration and level of post-tensioning the allowable axial load is given.

A Miniaturized Wideband Bandpass Filter Using Quarter-Wavelength Stepped-Impedance Resonators

In this paper, we present a simple method to design a miniaturized wideband bandpass filter with suppression of the third harmonic, using only two quarter-wavelength stepped-impedance resonators (SIRs). The resonant modes of the quarter-wavelength SIR, depending on the impedance ratio (K) and electrical length ratio (α), are discussed first. As to setting the resonant frequency of the SIR for the lower band edge of the required band, the size parameters of two quarter-wavelength SIRs can be determined by selecting the desired impedance ratio (K) and length ratio (α). By using the opposite directional arrangement of two SIRs with direct taped input/output ports, the wideband response can be formed. A filter example is shown in this study to address this simple design procedure. The measured results of the fabricated filter have a wide passband response from 3.3 to 5.8 GHz, with an insertion loss of 1.5 dB, a return loss of 20 dB, an extended bandwidth ration of 55%, a low-average group delay of less than 0.75 ns, and a stopband from 6 to 12 GHz, with an attenuation level of 20 dB. Due to the similar 0° feeding, a transmission zero at 8.3 GHz appears near the band edge; thus, improving the band selectivity. The proposed filter can have a very simple structure and a miniature size. Simulated results and measured results are in good agreement.

Current Control of Grid-Tied LCL-VSI With a Sliding Mode Controller in a Multiloop Approach

Despite several studies and approaches, the design of current controllers for grid-connected converters via LCL filters is still a challenging task. This is mainly due to the parametric uncertainties and the grid background voltage distortions to which the system is submitted. In order to overcome these inherent system challenges, this paper proposes a multiloop control framework that simplifies the system dynamics of the overall circuit by splitting it in two equivalent sub-circuits. An inner loop is implemented as a fast sliding mode controller that controls the filter capacitor voltage in a fast and robust way. As a result, the plant, viewed by the outer loop, yields a voltage-controlled voltage source connected to the grid through an L filter. Thus, multiple resonant controllers are included in the state-space representation of this simplified system, allowing the design of a state-feedback controller in the outer loop for asymptotic tracking of the grid current with disturbance rejection of the grid background voltage. Here, a discrete linear quadratic regulator algorithm is used for designing the state-feedback gains. A simple design procedure is presented, as well as simulations and experimental results, to show the good performance of the proposed control scheme even under significant uncertainties and disturbances of the system.

Using TDA underneath shallow foundations: simplified design procedure

ABSTRACTTire recycling and reuse in North America and worldwide have increased considerably, with the aim of reducing the harmful effects of scrap tires on the environment. Accordingly, the use of tire derived aggregates (TDA) in civil engineering applications is on the rise at an unprecedented rate. In comparison to conventional backfill aggregates, TDA is an inexpensive, lightweight material that costs about 25% of the cost of conventional backfill. Thus, there is an increasing trend of using TDA under shallow foundations as a lightweight backfill alternative. However, limited information exists for the design of shallow foundations built on TDA. Hence, the main objective of this paper is to develop a simplified design procedure for shallow foundations built over a TDA layer. Rigorous finite element models were developed and validated using field tests results. Subsequently regression analyses were used to develop the proposed ultimate bearing capacity equation, taking into account the granular layer thickness, TDA layer thickness, footing width, footing shape, footing depth, and the allowable settlement.

Output feedback-based consensus control for nonlinear time delay multiagent systems

This paper focuses on the leader-following consensus problem for a class of identical nonlinear time delay multiagent systems. Different from the existing results, it is the first time that an output feedback-based consensus control algorithm is proposed for the multiagent systems based on a fixed directed topology. A novel dynamic compensator is constructed for each follower by only using the follower output and the relative output information of its neighbor agents. The distributed controller is designed for each follower based on the compensator, which is independent of time delays in the agent state. It is proved strictly that each state variable of followers can asymptotically track that of the leader based on the constructed controller. The conditions imposed on nonlinear terms are relaxed and the proposed algorithm has a simple design procedure. Moreover, the proposed control design method is applied to the consensus problem of chemical reactor systems. The simulation results illustrate the effectiveness of the proposed consensus protocols.

Full-State Feedback Control of Back-to-Back Converters Based on Differential and Common Power Concepts

The back-to-back (BTB) converter is one of the most popular converter topologies for the control of electrical machines, power transmission systems, and power quality applications. The conventional cascade control structure is commonly used due to its simple design procedure and reliable operation. However, the bandwidth of the dc-link voltage controller has to be limited in order to avoid instability issues and be restrictive in high-performance applications. This paper presents a differential- and common-current (power)-based state-feedback control for BTB converters. This controller features a fast control of active and reactive powers, and a stiff regulation of the dc-link voltage. A theoretical analysis of the proposed controller along with a strategy for current limiting is presented. Its robustness was tested against variations of the filter parameters, the dc capacitance, the grid inductance, and the grid voltage values. The controller was experimentally validated under nominal operation, voltage sags, and connected to a weak grid by using a 15-kVA BTB converter in a laboratory test network.

Design and development of low-cost HDRBs seismic isolation of structures

This paper presents a simplified procedure for the preliminary seismic design of high damping rubber bearings (HDRBs) for seismic isolation of structures. The procedure is consistent with the ASCE 7-16 specified seismic design for isolated structure, and starts defining the seismic base shear coefficient (CS) demand for superstructure, reduced by an appropriate response modification factor (RI) for isolated structure. The target time period for isolated structure is identified from the (CS/RI) versus time period plot, corresponding the available base shear capacity of structure. The required lateral shear stiffness of HDRBs is calculated, assuming a reasonable height-to-length ratio of bearing. The preliminary design suggests the required dimensions (height, width and length) of bearing, required thickness of elastomers and number of steel shim plates. The proposed procedure was validated for the seismic isolation of three-story deficient RC frame structure, located in a high seismic zone with a design basis PGA of 0.44 g. Representative reduced scale bearings were locally produced and tested on shake table, using an acceleration time history record of 1994 Northridge earthquake, through multi-levels excitations ranging from 0.10 to 1.0 g. The hysteretic and shear force–deformation response curves were analysed to develop constitutive relationship and hysteretic model for HDRBs. The derived hysteretic model parameters were incorporated in SeismoStruct, using plastic and bi-linear hysteretic models, for testing and validation against the shake table tests. The numerically predicted to experimentally observed peak displacements/forces exhibited a little over-prediction using bi-linear hysteretic model while a little under-prediction using plastic hysteretic model. Combining results from both the hysteretic models, and averaging, minimized the average error to less than 0.10%. Comparative seismic analysis of both as-built and isolated frames was carried out for both design basis earthquakes DBE and maximum considered earthquake MCE (considered as 3/2 of DBE), showing promising behaviour of the simplified design procedure and locally produced HDRBs.

Uniform damping ratio-based design method for seismic retrofitting of elastoplastic RC structures using viscoelastic dampers

A simple design procedure is proposed for seismic retrofitting of existing structures using viscoelastic dampers (VEDs) based on the uniform damping ratio (UDR) concept to make full use of each damper. The UDR concept states that the equivalent damping ratios, which represent the energy dissipation capacities of the dampers, are the same for each installed VED. The stiffness and damping characteristic parameters of the damped structure can be formally decoupled using UDR-based derivations, which simplify the determination of the VEDs’ parameters. The generalized single-degree-of-freedom method and pushover analysis are adopted for a fast estimation of the seismic response of the damped elastoplastic structure. Taking the response reduction ratio as the design target, a seismic retrofit design procedure is proposed based on the UDR concept to meet the performance demand. Finally, a six-story frame is adopted to illustrate the proposed design method. The dynamic analysis results show that the seismic responses of the structure are well-controlled, as expected, and that the installed VEDs are used effectively. The conclusion can be drawn that the UDR-based design method for retrofitting an existing structure using VEDs is rational and effective.

A simplified approach to the dynamic effective thickness of laminated glass for ships and passenger yachts

In the last years, after the economic crisis that modified the super and megayacht market and construction, the project focus of shipyards and owners has been moved from the research of higher performances and whimsical exteriors to more classic aesthetics and higher level of onboard comfort. This first aspect has led to the use of larger openings on superstructures’ sides in order to enlarge windows and bring more natural light onboard vessels. The request of more comfortable units has granted a strong effort to find new solutions in order to reduce the noise and vibration level, dealing in particular to the structural elements with higher noise radiations, such as dampers, pillars and windows. The aforementioned trends is reflected on a more intensive use of glazed windows onboard, that have led to non-trivial problem of both structural response (since the structural component are reduced in order to enlarge opening) and NVH assessment, considering that glued glass panes act as an harmonic speakers, having natural frequencies closed to ones of the main superyacht excitations. In this paper, a simplified interactive design procedure for laminated glass used onboard super and megayacht is provided; in particular, authors developed a model for the calculation of a simplified dynamic effective thickness of laminated glasses, in order to increase the reliability of the modelling of glazed panes, with the same dynamic properties, in global numerical models of vessels.

Comprehensive Design Procedure and Manufacturing of Permanent Magnet Assisted Synchronous Reluctance Motor

Combining the main advantages of the permanent magnet synchronous motors and pure synchronous reluctance motors (SynRM), permanent magnet assisted synchronous reluctance motor (PMaSynRM) has been considered as a promising alternative to the conventional induction motors. In this paper, utilizing a macroscopic design parameter, called insulation ratio along the q-axis, and based on the magnetic reluctance concept, a simple and fast design procedure of synchronous reluctance motor is introduced. Then, the performance improvement of the machine by inserting the permanent magnets into the rotor body is investigated. After calculating the width of the magnetic flux barriers two dimensions Finite Element Method (FEM) analysis simulation of the designed motor is presented. Additionally, the performance characteristics of the designed motor such as torque producing capability and torque ripple are discussed. Furthermore, thermal analysis is conducted to determine the temperature distribution in the designed motor. Consequently, the prototype motor is fabricated and the experimental results are compared to the simulation results which validate the usefulness of the design method.

High‐Efficiency Ultrathin Dual‐Wavelength Pancharatnam–Berry Metasurfaces with Complete Independent Phase Control

AbstractMetasurfaces are planar structures that can offer unprecedented freedoms to manipulate electromagnetic wavefronts at deep‐subwavelength scale. The wavelength‐dependent behavior of the metasurface could severely reduce the design freedom. Besides, realizing high‐efficiency metasurfaces with a simple design procedure and easy fabrication is of great interest. Here, a novel approach to design highly efficient meta‐atoms that can achieve full 2π phase coverage at two wavelengths independently in the transmission mode is proposed. More specifically, a bilayer meta‐atom is designed to operate at two wavelengths, the cross‐polarized transmission efficiencies of which reach more than 70% at both wavelengths. The 2π phase modulations at two wavelengths under the circularly polarized incidence can be achieved independently by varying the orientations of the two resonators constructing the meta‐atom based on Pancharatnam–Berry phase principle. As proof‐of‐concept demonstrations, three dual‐wavelength meta‐devices employing the proposed meta‐atom are numerically investigated and experimentally verified, including two metalenses (1D and 2D) with the same focusing length and a vortex beam generator carrying different orbital angular momentum modes at two operation wavelengths. Both the simulation and experimental results satisfy the design goals, which validate the proposed approach.

A New Anti-Windup Compensator Based on Quantitative Feedback Theory for an Uncertain Linear System with Input Saturation

This paper devotes to the robust stability problem for an uncertain linear time invariant (LTI) feedback system with actuator saturation nonlinearity. Based on a three degree of freedom (DOF) non-interfering control structure, the robust stability is enforced with the describing function (DF) approach for an uncertain LTI system to avoid the limit cycle. A new type of anti-windup (AW) compensator is designed using the quantitative feedback theory (QFT) graphical method, which results in a simple design procedure and low-order AW control system. One of the most significant benefits of the proposed method is free of the non-convexity (intractable) drawback of the linear matrix inequality (LMI)-based approach. The analysis conducted on the benchmark problem clearly reveals that the proposed QFT-based anti-windup design is able to handle both saturation and uncertainty in a very effective manner.

ON THE OPTIMAL STRUT-AND-TIE MODELS AND DESIGN APPROACH FOR THE CABLE-PYLON ANCHORAGE ZONE

The cable-pylon anchorage zone is a typical D-region in a cable-stayed bridge, for which there has been no uniform simplified design method until now. In this paper, based on the extensive statistics of actual projects, topology optimization techniques and principle of minimum strain energy, two precise strut-and-tie models for the cable-pylon anchorage zone are proposed, which can clearly reveal the load-transmitting mechanism of the anchorage zone. Th e explicit geometric parameters of the strut-and-tie models are derived; thus, the designers can directly use these models. A simple design procedure to deploy prestressing tendons in the anchorage zone is also introduced, whose effectiveness and convenience are demonstrated by two design examples. A new design named the “one-way prestressing tendons PC cable-pylon” is also discussed regarding its application scope.

Empirical design formulae for series‐fed substrate integrated waveguides power divider

In this article, empirical design formulae for a unit cell of series-fed substrate integrated waveguide power divider for a wide range of power division ratio from 1:1 to 1:40 are presented. These formulae are determined through extensive simulations carried out in Ansys HFSS. The physical dimensions of the power divider for any given power division ratio can be directly determined through the design formulae presented in the article. A simple design procedure is discussed and verified with the help of experimental and simulation results. For experimental verification, a power divider is designed to operate in X band, and its prototype is developed on RT Duroid 5880, the measured results for this power divider are in close agreement with simulated as well as predicted results. Also, for validating the design procedure over a wide range of frequencies, many power dividers are designed with different power division ratios, different operating frequencies and different cut-off frequencies of TE10 mode. The cut-off frequency (fc) of TE10 mode is varied from 15 to 25 GHz, and the operating frequency is adjusted in between 1.2fc and 1.8fc. That is, 18–40 GHz, which is suitable for many microwave and millimeter wave applications. The obtained results are very close to the desired power division ratios.

An Effective Sliding Mode Control Design for a Grid-Connected PUC7 Multilevel Inverter

This paper proposes an effective sliding mode controller (SMC) for a grid-connected 7-level packed U-cell (PUC7) inverter. The aim is to design a simple controller that deals effectively with the complex control problem of the PUC7 inverter (multiobjective control problem). The selection of the control actions is achieved according to the system state error at every sampling time, regardless of the previous values, which makes the control technique model-independent. The control algorithm evaluates online two cost functions (one for each state error), which are derived on the basis of sliding mode theory, and it selects the optimal control input in order to satisfy the reaching conditions of the two cost functions. Compared with the existing solutions, the proposed SMC technique ensures lower average switching frequency by tuning the hysteresis bandwidth of the capacitor-voltage error. The fast implementation, needless of gains tuning, and simple design procedure are the main features of the proposed algorithm. Simulation and experimental results are presented to prove the effectiveness of the proposed technique in controlling the PUC7 inverter with high dynamic performance and robustness against disturbances and parameters mismatch.

Multi‐layer distributed protocols for robust cooperative tracking in interconnected nonlinear multiagent systems

SummaryWe develop a mixed graph and optimal control theoretic formulation to design a robust cooperative control protocol for a large‐scale multiagent system with partially known interconnected first‐, second‐, or mixed first‐ and second‐order dynamics. In each case, we transform the control protocol design task to a robust communication graph design problem, which, from a cyber‐physical perspective, is interpreted as the control layer design problem for an interconnected system with unknown agent layer dynamics. According to this viewpoint, each state variable has its own control layer communication topology separate from the other state variable's communication topology and the unknown agent layer interconnection topologies. We prove that all cooperative, decentralized, and centralized tracking protocols can be treated as a single design problem and, by deriving closed‐form solutions for the robust control layer topologies, we further provide a simpler design procedure, which is only based on the matrix manipulations. Aside from the linear implementation of the protocol and the connection of the proposed formulation to the well known rules‐of‐thumb in optimal control theory, this creates a higher potential to transfer ideas to industry. Modeling uncertainties tolerable by a given control layer topology is analyzed, and a preliminary performance‐oriented analysis and design approach for large‐scale interconnected systems is discussed. We show that exactly the same steps can be followed to design appropriate control layers for both tracking and stabilization.