Proposed Hybrid Control Scheme Research Articles

A practical leader–follower hybrid control scheme for wheeled mobile robots

This paper addresses the problem of tracking control of wheeled mobile robots in leader–follower formation. By applying the backstepping technique, a hybrid control scheme consisting of continuous control and intermittent control is proposed, and leader–follower formation tracking is achieved in the presence of model uncertainty and external disturbance. A relationship between the intermittent control width and control gain and the convergence of the position errors is obtained for the tracking accuracy estimation. As a special case, the concerned intermittent control can be converted to impulsive control with a sufficiently small control width, and tracking of the trajectory can be realized by directly driving the state variables of the follower at well-designed discrete instants. The main novelty of the proposed hybrid control scheme is to drive the tracking errors into a preset region via intermittent control (or impulsive control) signals and then achieve the tracking goal in the practical sense via continuous control signals. An example with the corresponding numerical simulations and experimental tests is given to illustrate the effectiveness of the proposed method.

Power quality improvement in distribution generation with renewable energy sources using hybrid GBDT-BCMO approach

ABSTRACT This paper presents a hybrid control system designed to improve power quality in grid-integrated hybrid renewable energy sources (HRES). The proposed hybrid control scheme is a hybrid approach gradient boosting decision tree and balancing composite motion optimisation, named GBDT-BCMO. The goals outlined above are the focus of GBDT-BCMO. The GBDT machine learning technique is enhanced using the BCMO method. GBDT method is trained on inputs like previous instantaneous energy of obtainable sources and current time required load demand based on target reference power. Based on load variation, GBDT-BCMO control system creates PI controller gain parameters to generate optimal control signal and manage HRES energy. The prediction process of the present method undertakes variations on system parameters, like reactive and real power and DC voltage. The proposed GBDT-BCMO system improves the power system damping and creates line voltage, giving reactive power compensation. The proposed methodology is then carried out in MATLAB/Simulink platform, and the performance is analysed. The behaviour of the proposed system is related with other systems. The proposed method ranges from 0 to 22.1 V. The BCMO system ranges from 0 to 22. The ALO system ranges from 0 to 22 V. The BAT Algorithm ranges from 0 to 22.0 V.

Fractional-Order Sliding-Mode Control and Radial Basis Function Neural Network Adaptive Damping Passivity-Based Control with Application to Modular Multilevel Converters

This paper proposes a hybrid control scheme that combines fractional-order sliding-mode control (FOSMC) with radial basis function neural network adaptive damping passivity-based control (RBFPBC) for modular multilevel converters (MMC) under non-ideal operating conditions. According to the passive control theory, we establish the Euler–Lagrange (EL) models of positive and negative sequences based on the unbalanced grid. A passivity-based controller that satisfies the energy dissipation law is designed. To enable rapid convergence of the system energy storage function, a radial basis function neural network (RBFNN) is introduced to adjust the injection damping adaptively. Additionally, a fractional-order sliding-mode controller (FOSMC) is designed. The fractional-order sliding mode surface used can improve tracking performance, and effectively suppressed the undesirable chattering phenomenon compared to the traditional sliding-mode control (SMC). Finally, combining the two control methods can effectively solve the issue of passivity-based control (PBC) being too dependent on parameters. The proposed hybrid control scheme enhances the ability of the system to resist disturbances, and improves its overall robustness. Simulation results demonstrate the feasibility and effectiveness of this control method.

Parasitic Component Small-Signal Modeling and Control of a Practical CLLC Resonant Converter

This article presents a comprehensive characterization of an asymmetric resonant CLLC dc/dc converter plant transfer function obtained using a generalized harmonic approximation (GHA)-based small-signal modeling approach. The effect of circuit parasitic components is comprehensively considered while deriving this model, and a quantified comparison of the resultant plant frequency response with a conventional first harmonic approximation (FHA)-based model is presented, which provides the designer insightful findings to design a robust and noise immune closed-loop compensator. Furthermore, a thorough explanation of a sliding mode control (SMC) along with detailed parameterization of the controller coefficients is provided by analyzing the system’s dynamic behavior and comparing the response with a conventional proportional–integral (PI)-based controller. In addition to the objective of designing a robust SMC controller, a phase shift-based secondary side modulation is introduced, which facilitates a significant reduction in the secondary side switching losses, thus enhancing the steady-state efficiency of the overall system. To validate and benchmark the open-loop plant response and controller dynamics, detailed steady-state results are elucidated for a 400–28- and 400–24-V voltage conversion at a rated load of 1 kW, with a resonant frequency of 500 kHz. Furthermore, a comprehensive experimental comparison between the proposed hybrid control scheme and the conventional PI controller is shown for two dynamic load changes corresponding to 10%–90% load step-up and 90%–10% load step-down. Quantification of dynamic response portrays a settling time reduction of 46.4% and an over/undershoot reduction of 33%, thus validating the robustness of the proposed control scheme.

A Multimode Control Scheme for Output Regulation and Voltage Balancing in a Stacked-Switch Resonant Converter With Extended High Efficiency for Wide Gain Range Applications

In this article, a new hybrid comprehensive multimode control system is proposed for a stacked-switch bidirectional CLLC resonant converter for wide voltage gain applications. By configuring the presented leg with different switching patterns, the presented leg in the converter can operate in different modes: full-wave (FW), half-wave (HW), or voltage-doubler (VD) through the converter’s built-in circuit redundancy. The proposed hybrid control scheme consists of different control modes: variable frequency modulation, pulse-width modulation (PWM), and asymmetric PWM (APWM) control. Correspondingly, four voltage gain curves are derived from the proposed converter. With the proposed approach, the converter is able to achieve constant voltage regulation while constraining the range of switching frequency, allowing very high efficiencies to be realized for a wide range of input voltages. Soft-switching is achieved for all the semiconductor devices for the entire operating range. The steady-state and dynamic performances of the proposed hybrid comprehensive control system are verified through a proof-of-concept 400-V <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim ~1$ </tex-math></inline-formula> -kV/ 700-V, 1-kW laboratory prototype. Results confirmed that the efficiency is maintained between 95.03% and 96.97% throughout the specified input voltage range.

Reliability and Cost Minimization of Renewable Power System with Tunicate Swarm Optimization Approach Based on the Design of PV/Wind/FC System

A hybrid control scheme for power system reliability of hybrid renewable energy sources (HRES) such as solar photovoltaic-wind energy and hybrid fuel cell is presented in this paper. The proposed hybrid control scheme is joint execution of Tunicate Swarm algorithm (TSA). Here, the TSA is used to diminish the cost function and exploit the power system reliability. The major purpose of this work is to diminish the cost in numerous conditions, as wind power, photovoltaic and fuel cell. Here, the TSA technique is trained on inputs such as earlier instantaneous energy of the available sources. The TSA control system creates the gain parameters deliver the optimal control signal and achieve the RES power. Then, the proposed scheme is performed on MATLAB/Simulink platform. The behavior of proposed scheme is related with existing schemes as MA-RBFNN. The efficiency of the DE, NSGA-II, NSGA-III, MA-RBFNN and proposed technique is 82.136%, 77.26588%, 80.7532%, 97.52470% and 97.83099%.

Hybrid Approach Named HUAPO Technique to Guide the Lander Based on the Landing Trajectory Generation for Unmanned Lunar Mission.

This manuscript proposes a hybrid method for landing trajectory generation of unmanned lunar mission. The proposed hybrid control scheme is the joint execution of the human urbanization algorithm (HUA) and political optimizer (PO) with radial basis functional neural network (RBFNN); hence it is named as HUA-PORFNN method. The HUA is a metaheuristic method, and it is used to solve several optimization issues and several nature-inspired methods to enhance the convergence speed with quality. On the other hand, multiple-phased political processes inspire the PO. The work aims to guide the lander with minimal fuel consumption from the initial to the final stage, thus minimizing the lunar soft landing issues based on the given cost of operation. Here, the HUAPO method is implemented to overcome thrust discontinuities, checkpoint constraints are suggested for connecting multi-landing phases, angular attitude rate is modeled to obtain radical change rid, and safeguards are enforced to deflect collision along with obstacles. Moreover, first, the issues have been resolved according to the proposed HUAPO method. Here, energy trajectories with 3 terminal processes are deemed. Additionally, the proposed HUAPO method is executed on MATLAB/Simulink site, and the performance of the proposed method is compared with other methods.

Research on position/force hybrid control of an FFHD robot with EHS-actuators

An Electro-Hydraulic Servo (EHS) Four-Footed Heavy-Duty (FFHD) robot is designed and developed in this work. An integration layout cylinder design scheme for the non-lightweight EHS four-footed robot with high loads and hip joint torques is proposed, and a mathematical element analysis model for a parallel EHS cylinder system is derived. Multiple inherent characteristics of the parallel-executed cylinder integration system model are then further explored. Based on the controllable functional requirements of interconnected joints and the influence reduction in internal force coupling, a force/position hybrid control scheme for the parallel-executed cylinder is determined, and the force/position signal module design unit is used to solve the force/position hybrid control in reverse. The implementation process of magnetic flux compensation and speed compensation is discussed in detail, considering the inherent requirements of the EHS-executed cylinder force control unit module. A compliant controller is then applied to the EHS-executed cylinder force unit module, and the proportional integral derivative (PID) controller is determined in the EHS-executed cylinder position control unit module. The compound control strategy proposed in this paper is verified on a parallel EHS platform. The experimental verification results reveal that the values of position/force attenuation amplitude and lag phase are no greater than 10.0% and 20°, respectively. The feasibility of the interconnected implementation of the proposed hybrid control scheme is then analyzed. The conclusions obtained in this research provide relevant insights for the application of FFHD robot control systems.

Stable cargo transportation of partial space elevator with multiple actuators

This work proposes a novel hybrid control scheme to stabilize a partial space elevator with unknown tether tensions in cargo transportation. The tether tensions are first estimated by a new observing method. The control scheme contains two controllers. With the estimated tensions, Controller I predicts the optimal reference climber speed implemented by the actuator on the climber. When the climber is moving at the reference speed, a novel observer-based super twisting sliding mode control law is proposed for Controller II to eliminates possible disturbances and further stabilises the system in real-time. Simulation results reveal that with the observed tensions, the proposed hybrid control scheme is very effective and accurate in stabilizing the partial space elevator actuated by multiple actuators in the cargo transfer period.

Trajectory tracking control for electro-optical tracking system based on fractional-order sliding mode controller with super-twisting extended state observer

This paper investigates a trajectory tracking control scheme for electro-optical tracking systems subject to friction and other nonlinear disturbances. The proposed approach is based on a super-twisting extended state observer (ESO) and a fractional-order nonsingular terminal sliding mode (FONTSM) with a switching-type reaching law. The novel hybrid control scheme exhibits the following advantageous characteristics. First, the extended state observer injected with a super-twisting algorithm is capable of simultaneously estimating the friction and other nonlinear disturbances without detailed knowledge of the precise friction and disturbance models. Second, the FONTSM surface enhances the control accuracy and robustness, and provides a more flexible controller structure than its integer counterpart. Third, a novel switching-type reaching law is utilized to achieve fast response, constraining chattering in the system. Additionally, the finite-time convergence of the adopted ESO and the finite-time stability of the control system are demonstrated based on the rigorous Lyapunov criteria. Finally, the effectiveness of the proposed hybrid control scheme is demonstrated for an electro-optical tracking system via trajectory tracking experiments.

Performance optimisation of the grid‐connected flyback inverter under improved hybrid conduction mode

In the unfolding-type interleaved two-switch flyback inverter (ILTFI) operating in discontinuous conduction mode (DCM), the hybrid control strategy combining the one-phase DCM and the two-phase DCM has a significant impact on improving the efficiency under all load conditions. In the situation where the marginal power of this control strategy is increased, the converter may enter CCM. Consequently, the converter cannot track the reference current and the output current quality is notably decreased. To tackle this issue, a novel hybrid control method is proposed which varies the switching frequency based on the output power. The proposed approach is immune to the loss analysis and power losses of the components. Hence, it is independent of components selection and their characteristics. In this case, the smooth transition between the one-phase and the two-phase operation modes is guaranteed without affecting the output power quality and the stability of the converter in DCM. The control complexity of the proposed scheme is low and the converter can be easily controlled in DCM. The performance of the flyback microinverter with the proposed hybrid control scheme is verified by the simulation and the experimental results together with the loss analysis.

Adaptive intelligent terminal sliding mode controller for stabilizing a chaotic plasma torch system

In this article, a novel adaptive intelligent control scheme is proposed to stabilize a chaotic nonlinear system with unknown dynamics in the presence of uncertainties and external disturbances. The proposed control scheme is a combination of terminal sliding mode, adaptive, and neural controllers. Terminal sliding mode control provides appropriate finite-time stability and robustness against uncertainties and external disturbances. A neural controller is used to provide suitable control action to eliminate chattering when the sliding surface is close to zero. For this purpose, a fuzzy module with simple rules is used to change the contributions of two neural and terminal sliding mode controllers, that is, when the sliding surface has a value around zero, the neural controller will take the control of the system to reduce chattering, and when the sliding surface is far from the zero region, the terminal sliding mode controller will control the system. Moreover, to cope with the unknown dynamics of the system, an online adaptive neural network is also used to approximate the unknown dynamics of the system. This hybrid control scheme is capable to decrease the contribution of the terminal sliding mode in the convergence region of the sliding surface which leads to the elimination of chattering. The combination of the several techniques to use the advantages of all the methods makes the proposed hybrid control scheme as an effective and practical scheme. Simulation results on a chaotic plasma torch system indicate the efficiency of the proposed control scheme in chattering elimination, high convergence, and also show the superior performance compared with the existing methods in the presence of disturbance and uncertainty.

Singular-perturbed control for a novel SEA-actuated MBT autoloader subject to chassis oscillations

Autoloaders that replace the human loaders performing ammunition transferring tasks in main battle tanks have been confronted with the problem of poor compliance abilities. To solve this problem, a novel autoloader with novel compliant actuators-SEAs (series elastic actuators) is firstly proposed in this paper. However, compliant actuators will lead to the problem of flexible vibrations. Moreover, the traditional autoloaders still suffer from the problem of poor positioning accuracy caused by the base oscillations. Finding a control strategy that achieves the vibration suppression and the accuracy positioning is nontrivial. In this work, we propose a hybrid singular-perturbed control scheme which consists of a derivative-type control and a piecewise-PD tracking control. Simulation results: (1) demonstrate the effects of the proposed hybrid control scheme, (2) show it’s superiority in positioning accuracy compared with traditional PD control, (3) further show it’s robustness to not only base oscillations but also inertial uncertainties.

Robust hybrid control law for a boost inverter

A robust hybrid control for a boost inverter is proposed in this paper. This control presents the particularity of considering the real nature of the dynamics, which means, the continuous-time dynamics, voltages and currents, and the discrete-time dynamics, the switching of the transistors. Likewise, due to implementation issues a minimum dwell time is introduced in the control loop scheme. Uniform global asymptotic stability is guaranteed, ensuring that the tracking error of the system output enters into a small neighborhood of zero. Moreover, robustness guarantee with respect to parameter variations, in terms of an error tracking output regulation, are also provided here. The effectiveness of the proposed hybrid control scheme is illustrated in simulation.

An Improved Adaptive Control Strategy in Grid-Tied PV System With Active Power Filter for Power Quality Enhancement

This article investigates the power quality enhancement of a grid-tied photovoltaic (PV) distribution system by employing a fuzzy logic proportional-integrator-derivative multiple complex coefficient filter multiple second-order generalized integrator frequency-locked loop (FLPID-MCCF-MSOGI-FLL) hybrid control scheme based shunt active power filter. The MSOGI-FLL reference current generation strategy is implemented to mitigate the current harmonics by extracting the fundamental constituents (FCs) from the nonlinear load currents, whereas an MCCF is employed to separate the FC from the distorted grid voltages and eliminates the voltage harmonics during extremely polluted grid voltage condition. The main objective of using FLPID is to maintain the stable power between dc and ac sides by regulating the dc-link voltage constant under transient conditions. To track the maximum power from the PV panel under varying environmental condition, the particle swarm optimization based perturb and observe technique is used in this article. The comparative analysis is analyzed to check the effectiveness of the proposed hybrid control scheme with existing and adaptive control techniques in respect of power quality, better dc offset rejection, better FC and frequency extraction, and grid synchronization. The system with the proposed control scheme is simulated on MATLAB/Simulink and validated in a real-time field-programmable gate array platform under different test scenarios. In conclusion, the harmonic content of grid currents and voltages is found well within the IEEE-519 standard limits.

Hybrid Passive/Active Vibration Control of a Loosely Connected Spacecraft System

In this paper, a hybrid passive/active vibration (HPAV) controller of a loosely connected spacecraft consisting of a servicing satellite, a target and an X-shape structure isolator is first proposed to suppress vibrations of the system when subjected to the impulsive external excitations during the on-orbit missions. The passive dynamic response of the combined system can be adjusted appropriately to achieve the desired vibration isolation performance by tuning the structural parameters of the bio-inspired X-shape structure. Moreover, the adaptive control design through dynamic scaling technique is selected as the active component to maintain high vibration isolation performance in the presence of parameter uncertainties such as mass of the satellite platform, the damping and rotation friction coefficients of the X-shape structure. Compared with the pure passive system and the traditional spring-mass-damper (SMD) isolator, the HPAV strategy witnesses lower transmissibility, smaller vibration amplitude and higher convergence rate when subjected to the post-capture impact. Numerical simulations demonstrate the feasibility and validity of the proposed hybrid control scheme in suppressing vibrations of the free-floating spacecraft.

A Multilevel Distributed Hybrid Control Scheme for Islanded DC Microgrids

This paper proposes a multilevel hybrid control scheme, including grid control and node control, for an islanded 48-V solar photovoltaic-based low voltage dc microgrid that aims to overcome the drawbacks of centralized and decentralized control schemes. The analyzed microgrid includes a 35-kW rooftop solar system as the main power source at bus-1 with battery storage, 5-kW hybrid energy storage system (Vanadium Redox flow battery with super capacitor) at bus-2, and variable loads such as electrical vehicles at bus-3. In the case of a central failure, the proposed hybrid control scheme is capable of seamlessly switching between high bandwidth communication and low bandwidth communication channels of communications to implement a distributed control scheme. The central supervisory controller is responsible for updation of grid characteristics and sending/receiving information to/from local node controllers, which are responsible for bus voltage regulation and energy management. The control hierarchy features optimized and safe operation (charge and discharge) of storage devices in dc microgrids. The paper also demonstrates the application of battery-supercapacitor systems to absorb system transients during load changes. The simulation showcases the continuous flow of information and decision processes via each level of control while simultaneously taking into consideration the constraints of each subsystem. The scheme has been simulated in MATLAB/Simulink environment for various case studies to evaluate system robustness. Further, the proposed scheme has been tested experimentally with its prototype and its results are explored.

Power quality improvement in wind energy conversion system using hybrid SVPWM inverter control technique for THD reduction

Wind energy is an abundant and naturally occurring source of energy that is being widely researched and implemented in recent times on a global scale. Quality of power generated from these renewable energy systems greatly determines the efficiency of such implementations. This research paper investigates and proposes a hybrid control scheme for reducing the total harmonic distortion which severely degrades the quality of power from energy conversion systems. The proposed hybrid space vector modulation scheme is a variant and improvement of the conventional PWM schemes. The produce more fundamental components with least harmonics by combining the merits of sinusoidal PWM and triangular carrier signal. The proposed modulation scheme is implemented in a closed loop PI controller scheme and results have been compared against three variants of PWM techniques namely sinusoidal, random and space vector PWM techniques and a drastic reduction in THD and power spectral density is observed justifying the superior performance of the proposed hybrid control scheme.

RFLSA control scheme for power quality disturbances mitigation in DSTATCOM with n-level inverter connected power systems

In this paper, a hybrid control scheme is proposed for power quality mitigation in DSTATCOM connected n-level inverter system. The proposed hybrid control scheme is the joined execution of both the random forest search algorithm and lightning search algorithm (RFLSA). The novelty of the proposed hybrid control scheme is enhanced prediction capability with the involvement of lightning search algorithm (LSA), reliability, adaptive for all parameter variations and less execution time. Here, the gain parameters of the PI controller are predicted to provide the optimal control signal of the DSTATCOM using proposed RFLSA technique. The proposed method prediction process considers all type of variations in the system parameters like DC voltage, real and reactive power. Based on the minimum error objective function, the learning process of random forest search algorithm (RFSA) is enhanced by using the lightning search algorithm (LSA). Then, the proposed technique is implemented in the MATLAB/Simulink platform and the performance is evaluated. The behavior of the proposed technique has been successfully compared with existing techniques. Simulation results shows that the proposed technique has the capability of ensuring satisfactory dynamic response, high efficiency and diminished harmonics.

Hybrid Control Scheme for Three-Phase Multilevel Unidirectional Rectifier Under Unbalanced Input Voltages

In this paper, a hybrid control scheme for three-phase Y-connected multilevel bridgeless rectifier (TMBR) under unbalanced input voltages is presented, based on the mathematical model of the TMBR topology, with the emphasis on the discussion for power fluctuation suppression, dc-link capacitor voltages balancing and input current zero-crossing distortion elimination. With the hybrid control scheme, the power fluctuation can be suppressed and three-phase input currents can flow with a purely sinusoidal waveform, besides, three-phase dc-link capacitor voltages can be controlled to be equal to each other under unbalanced input voltages. Moreover, the proposed hybrid control scheme is applicable to all other three-phase three wire multilevel unidirectional rectifiers under unbalanced input voltages. The validity of the proposed control scheme is demonstrated by the mathematical deduction. The simulations and experimental results verify that, with the proposed control scheme, TMBR can stably operate not only under balanced input voltages but also under unbalanced input voltages.