Reconfigurable Control Research Articles

Spatially Resolved Dynamically Reconfigurable Multilevel Control of Thermal Emission

AbstractSpatially resolved dynamically reconfigurable control of thermal emission has comprehensive implications for fundamental science and technological applications, such as thermal camouflage and adaptive radiative heating/cooling. Materials and systems that can spatially control thermal emission with dynamic reconfigurability, simple manufacturability, and a large dynamic range have not been explored, so far. Here, a spatially resolved thermal emission control platform consisting of three components (a material with phase transition hysteresis, a thermal photonic device with a field‐optimized planarized structure, and an optically controllable patterning system) is built and validated. This platform presents excellent merits such as spatially resolved control of thermal emission, multilevel (up to nine levels) emission control with a large dynamic range of the emissivity modulation (0.19 for the insulating phase and 0.91 for the metallic phase) over a broad bandwidth (8–14 µm), and robust reconfigurability. The results demonstrate potential applications in the field of thermal photonics for information and energy harvesting.

Assessment of a Universal Reconfiguration-less Control Approach in Open-Phase Fault Operation for Multiphase Drives

Multiphase drives have been important in particular industry applications where reliability is a desired goal. The main reason for this is their inherent fault tolerance. Different nonlinear controllers that do not include modulation stages, like direct torque control (DTC) or model-based predictive control (MPC), have been used in recent times to govern these complex systems, including mandatory control reconfiguration to guarantee the fault tolerance characteristic. A new reconfiguration-less approach based on virtual voltage vectors (VVs) was recently proposed for MPC, providing a natural healthy and faulty closed-loop regulation of a particular asymmetrical six-phase drive. This work validates the interest in the reconfiguration-less approach for direct controllers and multiphase drives.

Seamless Mode Transition Technique for Virtual Synchronous Generators and Method Thereof

This article deals with a method for seamless transition of three-phase virtual synchronous generator, switched between off-grid and grid-interfaced modes and vice-versa. The proposed control strategy achieves two-fold advantages. First, it eliminates the need for synchronizing tools such as phase-locked-loops, and separate islanding detection techniques during unintentional islanding events; the controller is so formulated to adapt automatically during mode transitions, by inheriting synchronization and islanding detection tasks within itself. As a result, the controller does not require any control reconfiguration during mode transitions, unlike the conventional control methods. Second, it eliminates multiple feedback loops and the need for rigorous tuning of proportional-integral regulators in practical systems. In this method, only the inverter current and voltage sensors are used, and the control over grid-side static transfer switch is not mandatory. The mathematical formulation of the controller is depicted and the closed-loop stability of the system is analyzed using Eigen value stability analysis. The effectiveness of the control strategy is demonstrated through simulations and comparative analysis with the state-of-art control methods. Experimental results validate the performance of the system under different operating conditions.

Active versus passive fault-tolerant control of a redundant multirotor UAV

ABSTRACTThis paper considers actuator redundancy management for a redundant multirotor Unmanned Aerial Vehicle (UAV) under actuators failures. Different approaches are proposed: using robust control (passive fault tolerance), and reconfigurable control (active fault tolerance). The robust controller is designed using high-order super-twisting sliding mode techniques, and handles the failures without requiring information from a Fault Detection scheme. The Active Fault-Tolerant Control (AFTC) is achieved through redistributing the control signals among the healthy actuators using reconfigurable multiplexing and pseudo-inverse control allocation. The Fault Detection and Isolation problem is also considered by proposing model-based and model-free modules. The proposed techniques are all implemented on a coaxial octorotor UAV. Different experiments with different scenarios were conducted for the validation of the proposed strategies. Finally, advantages, disadvantages, application considerations and limitations of each method are examined through quantitative and qualitative studies.

Dynamic Modeling of Underwater Multi-Hull Vehicles

SUMMARYThis paper describes a modeling approach to compute the lumped parameter hydrodynamic derivative matrices of an underwater multi-hull vehicle. The vehicle, modeled as a multi-body underwater system and denoted as cluster, can be composed by heterogeneous bodies with known dynamic parameters, rigidly connected. The nonlinear dynamic equations of the cluster and its parameters are derived by means of a modular approach, based on the composition of single basic elements. The ultimate objective is to derive a mathematical description of the multi-hull system that captures its most significant dynamics allowing to design model-based motion controllers and navigation filters. The modular nature of the resulting model can be exploited, by example, when control reconfiguration is to be dealt with in the presence of (possibly multiple) failures. The numerical simulation of a hypothetical cluster is presented and discussed.

Fault-Tolerant Cooperative Control in a Wind Farm Using Adaptive Control Reconfiguration and Control Reallocation

High reliability and availability are crucial for cost-effective operation of any wind farm. In this regard, effective schemes for fault detection, diagnosis and accommodation need to be developed to improve the reliability and availability of wind turbines and consequently wind farms (groups of wind turbines). Addressing this issue in a wind farm, this paper proposes a novel fault-tolerant cooperative control scheme based on an adaptive control reconfiguration approach that is augmented with an innovative control reallocation mechanism in a cooperative framework. Applied to a wind farm, this scheme tackles the effects of power loss faults in wind turbines, whether mild (due to mild icing or debris build-up on rotor blades) or severe (due to heavy icing). Different simulations on a wind farm benchmark model indicate the high effectiveness of the proposed scheme.

Big data driven Hierarchical Digital Twin Predictive Remanufacturing paradigm: Architecture, control mechanism, application scenario and benefits

Remanufacturing is deemed to be an effective method for recycling resources, achieving sustainable production. However, little importance of remanufacturing has been attached in PLM. Surely, there are many problems in implementation of the remanufacturing strategy, such as inability to effectively reduce uncertainty, lack of product multi-life-cycle remanufacturing process tracking management, lack of smart enabling technology application in the full lifecycle that focusing on multi-life-cycle remanufacturing. After analyzing the reasons, through integrating smart enabling technologies, a new PLM paradigm focusing on the multi-life-cycle remanufacturing process: Big Data driven Hierarchical Digital Twin Predictive Remanufacturing (BDHDTPREMfg) is proposed. And the definition of BDHDTPREMfg is proposed. A big data driven layered architecture and the hierarchical CPS-Digital-Twin(CPSDT) reconfiguration control mechanism of BDHDTPREMfg are respectively developed. Then, this paper presents an application scenario of BDHDTPREMfg to validate the feasibility and effectiveness. Based on the above application analysis, the benefits of penetrating BDHDTPREMfg into the entire lifecycle are demonstrated. The summary of this paper and future research work is discussed in the end.

Reconfigurable Control of the Quasi-Parallel Voltage Regulator for Powering Laptop Processors

The quasi-parallel voltage regulator (VR) topology with a phase-shifted full-bridge (PSFB) converter and a synchronous buck converter (SBC) in quasi-parallel configuration gives high efficiency even with widely varying input voltage at high and medium loads but not at light loads. Moreover, the “loop gain shaping” approach to controller design for this converter does not give satisfactory dynamic performance. Therefore, this article proposes a state feedback controller which meets the stringent dynamic performance requirement of the VRs. Additionally, techniques to reconfigure the state feedback controller are proposed to operate this converter in different light-load operating modes to improve its light-load efficiency so that the converter becomes suitable for laptop VR application. In the light-load modes, the PSFB and the SBC operate alternately to regulate the load voltage, thereby saving the losses of one of the converters. At very light loads, a burst mode operation is proposed where both the converters remain inactive for most of the time, further increasing the efficiency. A unified control method which enables the converter to seamlessly change the operating modes of the converter, based on the computing load on the processor, is proposed and experimentally verified on a laboratory prototype for satisfactory performance.

3D Printable and Reconfigurable Liquid Crystal Elastomers with Light-Induced Shape Memory via Dynamic Bond Exchange.

3D printable and reconfigurable liquid crystal elastomers (LCEs) that reversibly shape-morph when cycled above and below their nematic-to-isotropic transition temperature (TNI ) are created, whose actuated shape can be locked-in via high-temperature UV exposure. By synthesizing LCE-based inks with light-triggerable dynamic bonds, printing can be harnessed to locally program their director alignment and UV light can be used to enable controlled network reconfiguration without requiring an imposed mechanical field. Using this integrated approach, 3D LCEs are constructed in both monolithic and heterogenous layouts that exhibit complex shape changes, and whose transformed shapes could be locked-in on demand.

Sensor Fault Tolerant Control for Aircraft Engines Using Sliding Mode Observer

This paper investigated the problem of fault estimation and fault-tolerant control (FTC) against sensor faults for aircraft engines. By applying a second order sliding mode observer (SOSMO) to the engine on-board model, estimations of the system states and sensor faults could be obtained simultaneously, and the result of state estimation was unaffected when using the reduced-order sliding mode system. This result gave rise to the idea to use the estimated states instead of physical sensor signal in the engine close-loop feedback control. Unlike those using passive FTC concepts, the tradeoff between control performance and robustness was inherently unnecessary. Meanwhile, compared to active FTC approaches, because any classical state/output feedback method can be directly applied to the proposed scheme without any controller reconfiguration, extra undesired dynamic responses caused by parameter reconfiguring were avoided. In this paper, the proposed FTC scheme was tested on the nonlinear model of a civil aircraft turbofan engine, and numerical simulation results showed satisfactory sensor FTC performance.

Efficient Model Predictive Control with Natural Fault-Tolerance in Asymmetrical Six-Phase Induction Machines

Multiphase machines allow enhancing the performance of wind energy conversion systems from the point of view of reliability and efficiency. The enhanced robustness has been traditionally achieved with a mandatory post-fault control reconfiguration. Nevertheless, when the regulation of x-y currents in multiphase drives is done in open-loop mode, the reconfiguration can be avoided. As a consequence, the reliability of the system increases because fault detection errors or delays have no impact on the post-fault performance. This capability has been recently defined as natural fault tolerance. From the point of view of the efficiency, multiphase machines present a better power density than three-phase machines and lower per-phase currents for the same voltage rating. Moreover, the implementation of control strategies based on a variable flux level can further reduce the system losses. Targeting higher reliability and efficiency for multiphase wind energy conversion systems, this work proposes the implementation of an efficient model predictive control using virtual voltage vectors for six-phase induction machines. The use of virtual voltage vectors allows regulation of the x-y currents in open-loop mode and achieving the desired natural fault tolerance. Then, a higher efficiency can be achieved with a simple and universal cost function, which is valid both in pre- and post-fault situations. Experimental results confirm the viability and goodness of the proposal.

Light Control of Localized Photobioconvection.

Microorganismal motility is often characterized by complex responses to environmental physico-chemical stimuli. Although the biological basis of these responses is often not well understood, their exploitation already promises novel avenues to directly control the motion of living active matter at both the individual and collective level. Here we leverage the phototactic ability of the model microalga Chlamydomonas reinhardtii to precisely control the timing and position of localized cell photoaccumulation, leading to the controlled development of isolated bioconvective plumes. This novel form of photobioconvection allows a precise, fast, and reconfigurable control of the spatiotemporal dynamics of the instability and the ensuing global recirculation, which can be activated and stopped in real time. A simple continuum model accounts for the phototactic response of the suspension and demonstrates how the spatiotemporal dynamics of the illumination field can be used as a simple external switch to produce efficient bio mixing.

Adaptive Backstepping Based Sensor and Actuator Fault Tolerant Control of a Manipulator

The purpose of this research is to propose and design fault tolerant control (FTC) scheme for a robotic manipulator, to increase its reliability and performance in the presence of actuator and sensor faults. To achieve the said objectives, a hybrid control law relying on observer and hardware redundancy-based technique has been formulated in this paper. Non-linear observers are designed to estimate the unknown states. The comparison of actual states and observed states lead to fault identification, this is followed by fault tolerance accomplished with redundant sensors. For actuator fault tolerance, fault estimation and controller reconfiguration techniques are applied in addition to nominal control law. Fault estimation is based on adaptive back-stepping technique and it is further used to construct actuator fault tolerant control. The proposed method is applied to a six degree of freedom (DOF) robotic manipulator model and the effectiveness of this technique is verified by LabVIEW simulations. Simulation results witnessed the improved tracking performance in the presence of actuator and sensor failures.

Field-Oriented Control of Multiphase Drives With Passive Fault Tolerance

Multiphase machines provide a continuous operation of the drive with no additional hardware in the event of one or more open-phase faults. This fault-tolerant capability is highly appreciated by industry for security and economic reasons. However, the steady-state postfault operation has only been feasible in previous works after the fault localization and control reconfiguration. Even though this is done at the software stage, the obligation to identify the faulty phases and store the modifications for every fault scenario adds further complexity. This article reveals that this software reconfiguration can be avoided if the field-oriented control strategy is designed to satisfactorily handle pre and postfault situations. Experimental results confirm the capability to obtain a suitable postfault operation without fault localization and control reconfiguration and, thus, achieving a passive/natural fault tolerance.

L- and LCL-Filtered Grid-Tied Single-Phase Inverter Transistor Open-Circuit Fault Diagnosis Based on Post-Fault Reconfiguration Algorithms

This paper presents a transistor open-circuit fault diagnosis method based on an average model and post-fault reconfiguration algorithms for a grid-tied single-phase inverter that transfers power bi-directionally. The transistor open-circuit fault occurrence is detected by comparing the average bridge arm pole-to-pole voltage deviation and threshold first. Then, the exact faulty transistor is identified by developed algorithms based on post-fault reconfiguration of control (PFRC) and of utilizing redundant leg (PFRUR). These two fault identification algorithms are suitable for different situations. Compared with the PFRUR, the PFRC can identify the faulty transistor without the help of redundant leg, but the identification time is longer. For inverters equipped with redundant leg already, the PFRUR can achieve faster identification speed so that inverters in reliability-oriented applications can return to normal operation after fault with short interruption. With average model, this method only requires existing signals sampled for control, thus it can be embedded in system easily without adding extra sensors and diagnosis circuits. The sampling frequency can be as low as switching frequency. Furthermore, this method is suitable for both inverters with L or LCL filters. Finally, experiments are carried out on a 550-W/10-kHz grid-tied single-phase inverter to verify the effectiveness.

Design and development of reconfigurable embedded system for real‐time acquisition and processing of multichannel ultrasonic signals

The study proposes a novel hardware-based architecture of the reconfigurable embedded system for the multi-channel immersion ultrasonic system. It provides the addressing-based analogue multiplexing scheme, which requires only one data acquisition unit and common on-chip storage for the multi-channel imaging system. It also provides unique channel reconfigurable facility to the user to modify the number of channels (up to 256 for pulse-echo and 512 for transmit-receive mode by installing only the partial front-end hardware (pulser, pre-amplifier) and without modifying the remaining data acquisition hardware (common-amplifier, digitiser) and back-end embedded system. The developed system further supports dynamic on-line reconfiguration of the analogue front-end hardware, real-time hardware-based data processing, and data transfer operation. The authors have implemented the addressing-based reconfigurable architecture of the coherent averaging for noise reduction. For the experimentation, the complete four-channel ultrasonic imaging system for immersion testing has been designed, developed, and evaluated in the laboratory. Furthermore, this study describes the capability of the proposed system by performing multi-channel real-time data acquisition, hardware-based coherent averaging, channel multiplexing-demultiplexing, reconfigurable control, and software-based post-processing. Here, they present the performance evaluation of the developed multi-channel system by carrying out the B-scan and C-scan image acquisition of the water-immersed mechanical components.

A Reconfigurable Cross-Connected Wireless-Power Transceiver for Bidirectional Device-to-Device Wireless Charging

This paper presents a reconfigurable cross-connected (CC) wireless power transceiver (TRX) operating at 6.78 MHz and implemented for bidirectional device-to-device (D2D) charging with high efficiency and small system volume. We propose, for the first time, a CC topology applied to a differential class-D power amplifier for significant switching loss reduction. Two delay-locked loops (DLLs) for each power NMOS transistor form the reconfigurable controller, realizing the adaptive deadtime control in the transmitter (TX) mode and the off-delay compensation in the receiver (RX) mode, leading to high power conversion efficiency and safe operation. To realize the inductive load for the TX mode in the whole coupling range at the resonant frequency, we use an on-chip tunable capacitor. Furthermore, we also study the power link efficiency in the D2D direct charging system and verify that the near-maximum power link efficiency can be inherently achieved in this scenario. The proposed wireless power TRX, fabricated in a 0.35- $\mu \text{m}$ CMOS process with 5-V devices, measured a peak D2D total efficiency of 77.2% when the output power is 0.7 W. The maximum charging power is 2.74 W with a total efficiency of 62.7% and the maximum transmission distance is 24 mm, both measured.

Synergetic Control for HVAC System Control and VAV Box Fault Compensation

Abstract Synergetic control is proposed for heating, ventilating and air-conditioning (HVAC) system control. The synergetic controller is developed using the nonlinear model of the HVAC system. Occupancy information in each zone is required in the design of the controller which offers inherent comfort according to the occupancy in the zone. The stability of the building system using the proposed control is verified through the Lyapunov approach. It is also proved that the synergetic controller is robust to external disturbances. Then, synergetic theories are used to design a reconfigurable control for damper stuck failures in variable air volume (VAV) to recover the nominal performance. Simulations are provided to validate the effectiveness of the proposed controller for a three-zone building.

Indirect robust suboptimal control of two-satellite electromagnetic formation reconfiguration with geomagnetic effect

As a novel approach to control the relative motion of a satellite formation, electromagnetic formation flight (EMFF) has some prominent advantages, such as no propellant consumption and no plume contamination, and has a broad prospect of application in such fields as on-orbit detection and optical interferometry. The current paper investigates the optimal control for the reconfiguration of a two-satellite electromagnetic formation using the nonlinear quadratic optimal control technique. Specifically, the effects of the Earth’s magnetic field on the EMFF satellites are analyzed, and then the nonlinear translational dynamic model of a two-satellite electromagnetic formation is derived by utilizing the analytical mechanics theory. Considering the high nonlinearity and coupling in the dynamic model and the actuator saturation, a closed-loop robust suboptimal control strategy based on the indirect robust control scheme and the θ-D technique is proposed with robust stability and optimality. To ensure a further reduction of control input, the designed suboptimal controller is modified by applying the Tracking-Differentiator. The feasibility of the derived translational dynamics and proposed control strategy for the robust reconfiguration mission is validated through theoretical analysis and numerical simulations.

Methodological Approach for Developing Reconfigurable Automation Systems

One challenge for the designers of the current industrial control systems consists of assuring the system reconfiguration at runtime, envisaged at system design time. This article focuses specifically on the fault tolerance to controller failures (as it is the most complex challenge) aiming at redistributing the responsibilities at runtime in order to finish the current production plan. Its applicability is illustrated by means of a case study that consists of a reconfigurable control application based on the IEC 61131-3 for a flexible assembly cell. A prototype software tool guides the developer during the development process. This approach contributes to develop more flexible control systems because they can react in case of a controller failure, to increase the system availability during its operation and to reduce the production downtimes to perform the maintenance tasks.