Hybrid Control Structure Research Articles

Control of extractive distillation processes with preconcentration for the separation of ternary azeotropic mixture ethyl acetate-ethanol–water in the face of multiple feed disturbances

The integration of preconcentration and solvent recovery functions is one of the effective ways to save energy consumption of extractive distillation processes for separating ternary azeotropic mixtures with a high content of one composition. However, the integration of various functions inevitably increases the difficulty of constructing robust control structures. In this paper, different proportion-integration (PI) control structures are investigated for the four-column extractive distillation with preconcentration process, while different PI and PI with model prediction controller (MPC) hybrid control structures are proposed for the three-column extractive distillation with integrated distillation column (TCED-IDC) process to deal with feed disturbances via taking the separation of ternary azeotropic mixture ethyl acetate-ethanol–water as a case study. The control structures are tested via introducing multiple feed disturbances including one feed flowrates disturbance and three feed compositions disturbances. The dynamic test comparison results show that the integration of preconcentration and solvent recovery functions causes a larger transient deviation in terms of dynamic responses of the individual optimal control structures. In addition, the integral of squared error of the TCED-IDC process are reduced by about 22 times after introducing the MPC in the face of feed disturbances.

A Hybrid Controller Enhancing Transient Performance for an Aerial Manipulator Extracting a Wedged Object

Autonomous aerial manipulation requires the capability to handle inevitable dynamic changes during physical interaction. Previously, very few studies have addressed the stability and transient performance of the scenarios involving abrupt changes in dynamics. This paper proposes a hybrid controller enhancing transient performance for an aerial manipulator extracting an object wedged in a static structure. This task incurs a significant jump in the interaction force on the end-effector so that the analysis using the concept of hybrid dynamical systems is required. To demonstrate the dynamic characteristics of the object-extracting aerial manipulator, we derive the dynamic equations for two flight modes, i.e., free-flight and object-extracting, and the rule of state jumps. Also, we design control strategies which enhance the transient performance during flight mode transition. Then, the stability of the proposed control law is proven, and the overshoot reduction after the object extraction is analyzed. To show the improved performance, we conduct plug-pulling experiments with a quadrotor-based aerial manipulator using the proposed controller and two different existing controllers. The comparative results confirm that our controller enables the aerial manipulator to maintain its stability after the flight mode transition and shows the best transient performance in overshoot minimization among three controllers. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —The motivation for this article is the desire to prevent unexpected collisions between obstacles and an aerial manipulator after the vehicle extracts a wedged object from a static structure. To resolve this problem, we present a hybrid control method for such tasks while avoiding an excessive overshoot after the extraction. This method can be utilized in tasks involving abrupt changes in the dynamic model such as retrieving a device attached to a tall structure, reclaiming an object in disaster recovery, or pulling a plug out of a socket. Unlike existing methods, the proposed method simultaneously considers the stability <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">and</i> the initial overshoot right after pulling the object out of the structure, by employing a disturbance observer (DOB) in a hybrid control structure. It can be utilized for the aerial manipulator to avoid collision in a narrow space or to keep it in a safe operation envelope even though the task requires producing a relatively large pulling force.

Hybrid Layer of Improved Interfered Fluid Dynamic System and Nonlinear Model Predictive Control for Navigation and Control of Autonomous Underwater Vehicles

This study introduces a hybrid control structure called Improved Interfered Fluid Dynamic System Nonlinear Model Predictive Control (IIFDS-NMPC) for the path planning and trajectory tracking of autonomous underwater vehicles (AUVs). The system consists of two layers; the upper layer utilizes the Improved Interfered Fluid Dynamic System (IIFDS) for path planning, while the lower layer employs Nonlinear Model Predictive Control (NMPC) for trajectory tracking. Extensive simulation experiments are conducted to determine optimal parameters for both static and dynamic obstacle scenarios. Additionally, real-world testing is performed using the BlueRov2 platform, incorporating multiple dynamic and static obstacles. The proposed approach achieves real-time control at a frequency of 100 Hz and exhibits impressive path tracking accuracy, with a root mean square (RMS) of 0.02 m. This research provides a valuable framework for navigation and control in practical applications.

Seismic Performance Comparison of Hybrid, Isolation, and Damping Control Structures through 1/2-Scale Shaking Table Tests Based on Chinese Standard

A hybrid control structure (HCS) using seismic isolation at the base and energy dissipating cladding panel system (EDCPS) in the superstructure was proposed to realize enhanced seismic performance objectives of the main structure and nonstructural walls. To verify the feasibility of the HCS and validate its advantages in controlling the damage of structures compared with a seismic isolation structure (SIS) and a damping structure (DS), 1/2-scale shaking table tests were conducted on a HCS, an SIS, and a DS designed based on Chinese Standard. The seismic performance of the three damage control structures under different earthquake levels and ground motions (i.e., normal and velocity pulse-type ground motions) were investigated, including the damage characteristic, global responses, and isolator and damper behaviors. The test results indicated that the HCS provided the best control effect and remained elastic under the maximum considered earthquake (MCE). In contrast, slight and moderate damage were observed in the main structures of the SIS and DS under the MCE, respectively. Under the service level earthquake, the seismic response of the HCS was similar to or even greater than that of the SIS. While under the design basis earthquake and MCE, the U-shaped steel dampers in the HCS yielded and partially dissipated the earthquake energy; thus, this resulted in an obvious reduction in the drift ratio compared with that of the SIS. No damage to the cladding panels was observed in the HCS and DS, which indicated that the EDCPS was effective in controlling damage to the panels. In addition, a velocity-pulse type ground motion and the peak ground velocity significantly influenced the seismic responses of the HCS, SIS, and DS, particularly under the MCE.

Hybrid dual-loop control method for dead-time second-order unstable inverse response plants with a case study on CSTR

Abstract Unstable processes are hard to stabilize as they contain one or more positive poles which result in unbounded dynamic behavior. The occurrence of the delay and positive zeros often creates more difficulty in controlling such unstable plants. Most control strategies meant for first-order unstable processes fail to stabilize and control the higher-order unstable processes. Hence, a new dual-loop hybrid control structure is suggested for dead-time unbounded second-order processes with positive/negative zeros. Inner-loop has a stabilizing PID controller. The PID controller parameters are derived by comparing the numerator and characteristic polynomial coefficients in the transfer function for internal-loop servo action. A fractional-order internal model controller (FOIMC) is used in the external-loop. Methods for the selection of outer-loop tuning parameter and fractional-order are also discussed. By comparing the simulation results with a contemporary single-loop scheme, the usefulness of the suggested scheme is proved. The suggested scheme is capable of minimizing the overshoot and improving the overall dynamic performance. Finally, the usefulness of the suggested scheme is also demonstrated by a case study on temperature control of a continuous stirred tank reactor (CSTR) during a first-order irrevocable exothermic reaction.

A Case Study of a Hydraulic Servo Drive Flexibly Connected to a Boom Manipulator Excited by the Cyclic Impact Force Generated by a Hydraulic Rock Breaker

This study deals with the mathematical modeling, dynamic analysis, hybrid control structure, and experimental tests of a hydraulic servo drive (HSD) flexibly connected by a vibration isolator as a spring damping device (SDD) to a boom manipulator excited by the cyclic impact force generated by a rock breaker. Based on the dynamic model of the HSD-SDD system, the frequency ratios of the rigid and flexible connections to the mass load were determined. The HSD-SDD model was saved as a Hammerstein model with unknown parameters. The dynamic linear part of the HSD-SDD model was adopted as an autoregressive model with an exogenous input (ARX) model. The online proportional integral derivative (PID) controller parameter-tuning algorithm was implemented in several steps. The PID controller tuning process occurs in real time, and the optimal setting of the PID controller depends on the critical ultimate gain and period set at the stability limit. A hybrid control structure consisting of a feedback controller and feedforward controller was proposed. A combination of input shaping and feedforward filters is used, thus the badly damped vibrations are more effectively compensated, resulting in better control accuracy of the HSD-SDD system. The goal of optimizing the hybrid control structure is to determine a feedforward filter coefficient that minimizes the objective function. Finally, the global minimum is calculated from the control error based on the measurement of the input and output signals. The highlight of this study is the development of a new hybrid control structure to compensate for badly damped vibrations.

Robust Secondary Frequency Control for Virtual Synchronous Machine-Based Microgrid Cluster Using Equivalent Modeling

The technology of virtual synchronous machine (VSM) is attracting interest of researchers as it controls converters mimicking the synchronous machine's response so as to provide inertial support for power electronics dominated smart grids. For the VSM-based microgrid, its slow dynamics are dominated by synchronous generators (SGs) and the VSM control loops, which makes it possible to model this microgrid into an equivalent SG (EqSG) model. This paper proposes a robust secondary frequency control design method for the VSM-based low voltage (LV) microgrid cluster (MGC) using equivalent modeling. The EqSG model is used to construct the MGC model so as to reduce the model order and the complexity of controller synthesis. Modeling errors caused by the EqSG model and different operating conditions are integrated into the MGC model as unstructured uncertainties. The proposed secondary frequency control strategy is based on the distributed-centralized hybrid control structure to coordinate frequency restoration among LV microgrids. Structured μ-synthesis is applied for tuning control parameters realizing H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> robust performance against unstructured uncertainties. To reduce the communication resource consumption, an event-triggered mechanism considering communication delay is introduced in the robust secondary frequency control strategy. The triggering condition is analyzed using a Lyapunov function to guarantee H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> robust stability. Simulation and real-time experiment results on a MGC composed of four CIGRÉ benchmark LV microgrids are presented to demonstrate the effectiveness of the proposed control strategy.

Advanced Application of Centralized Control for a Scanning Mirror System Based on EtherCAT Fieldbus

Distributed control is the most popular control strategy for controlling numerous slave devices. However, the performance of slave devices is hard to improve because the control algorithm is handled by the commercial slave devices. Therefore, this paper proposes a hybrid control structure that follows the concept of centralized control strategy and handles part of the control loop on the master computer in a distributed control system through EtherCAT fieldbus. In this study, different advanced control methods such as robust control and learning control were applied to handle the position control loop of a scanning mirror system in a selective laser melting (SLM) system with stringent demand of position error around 40 µm based on EtherCAT fieldbus. By designing a proper controller, the experiment results showed that the tracking performance was significantly improved. The tracking error dropped by about 80% after the proposed hybrid control structure was applied. By applying the proposed hybrid control structure, one can improve the high-performance-requirement devices, while reducing the calculation burden of the master computer for other low-performance-requirement devices by retaining the benefit of distributed control.

Design of smooth hybrid controllers for a class of non‐linear systems

Symbolic planning techniques rely on abstract information about a continuous system to design a discrete planner to satisfy desired high-level objectives. However, applying the generated discrete commands of the discrete planner to the original system may face several challenges, including real-time implementation, preserving the properties of high-level objectives in the continuous domain, and issues such as discontinuity in control signals that may physically harm the system. To address these issues and challenges, the authors proposed a novel hybrid control structure for systems with non-linear multi-affine dynamics over rectangular partitions. In the proposed framework, a discrete planner can be separately designed to achieve high-level specifications. Then, the proposed hybrid controller generates jumpless continuous control signals to drive the system over the partitioned space executing the discrete commands of the planner. The hybrid controller generates continuous signals in real-time while respecting the dynamics of the system and preserving the desired objectives of the high-level plan. The design process is described in detail and the existence and uniqueness of the proposed solution are investigated. Finally, several case studies are provided to verify the effectiveness of the developed technique.

Quadrotor UAV Position and Altitude Tracking Using an Optimized Fuzzy-Sliding Mode Control

Quadrotors are one of the Unmanned Aerial Vehicles (UAVs) that have many applications in the aerospace industries which require a high level of accuracy and innovation in control and stability. In this paper, a hybrid control structure is proposed for this system. The sliding mode controller (SMC) is the foundation of this control structure. This controller, despite its high stability capability for nonlinear systems, has two weaknesses: chattering phenomenon and high vulnerability to noise. The proposed solution is to incorporate the SMC and the Fuzzy intelligent controller because of its high flexibility against the changes in the system model conditions. The new Fuzzy-SMC resolves the SMC weaknesses significantly, but it is not optimized due to a lack of access to the system model expert information. In order to optimize the Fuzzy-SMC, it is necessary to have accurate structural information and specification of the system model which are not available for this case. The final proposed solution is to synthesize the Genetic Algorithm (GA) with the Fuzzy-SMC. In GA performance, each Fuzzy rule is regarded as a chromosome and at each stage, the best of chromosomes, containing the fastest responding, are passed on to the next generation as the elite. The rest combine to create the next generation by using combination and mutation methods. Thus, the Fuzzy-SMC operates based on optimized Fuzzy rules. The results of the simulation in MATLAB software clearly show that the state of quadrotor reaches the desired value and location at the appropriate time.

Unactuated Force Control of 5-DOF Parallel Robot Based on Fuzzy PI

This paper investigates the fuzzy position/force hybrid control for a class of 5-degree-of-freedom (DOF) redundantly actuated parallel robots. The position control law is designed based on the proportional-integral-differential (PID) for the 5-DOF redundantly actuated parallel robot. The fuzzy proportional-integral (PI) redundant actuation force control law is designed based on the position/force hybrid control structure for the 5-DOF redundantly actuated parallel robot. The optimum driving force is obtained in the presence of interference, and the force tracking performance of the fuzzy PI controller is better than the conventional PI controller under the interference condition. Based on the fuzzy position/force hybrid controller, the tracking performance of the closed-loop system for the 5-DOF redundantly actuated parallel robot is improved by using the fuzzy position/force hybrid controller and the interference is eliminated effectively in the control system design. Finally, the co-simulation results of ADAMS and MATLAB/SIMULINK are given to show the effectiveness and advantages of the proposed methods compared with the conventional PI controller.

Control of the Fluidized Bed Combustor based on Active Disturbance Rejection Control and Bode Ideal Cut-off

The fluidized bed combustor (FBC) boiler faces many control challenges such as high-order dynamics and strong nonlinearity. A hybrid control structure combining active disturbance rejection control (ADRC) and Bode ideal cut-off (BICO) is proposed to handle with these control difficulties and speed up the output responses. An empirical tuning procedure is summarized for the hybrid control structure. Simulation results show that the hybrid control structure has the best tracking performance compared with other control strategies. In addition, the hybrid control structure can obtain the satisfactory disturbance rejection performance when the FBC system has the coal quality variation or input disturbances. The superiority of the hybrid control structure can ensure the satisfactory control performance and shows a great potential in industrial applications.

Fractional-order internal model control algorithm based on the force/position control structure of redundant actuation parallel robot

This article proposes a new control structure for the complex redundant actuation parallel robot based on force/position hybrid control structure. The traditional proportional–integral–derivative control method, integer-order internal model control method and fractional-filter internal model control–proportional–derivative control method are used in the position structure of force/position hybrid control. The fractional-filter internal model control–proportional–derivative control method is used in the position loop of the permanent magnet synchronous motor to reduce the position error. A fractional-order theory with the internal model control method is used in redundant actuation force control structure, which can improve the control precision of the driving force of the parallel robot. The Admas/Matlab simulation results show that the proposed method outperforms other methods and can obtain good robustness and tracking performance.

Passive Approach for Fault Tolerant Controller Using Hybrid Controller Structure for Effective Level Control of Conical Tank System

The Article Propose An Efficacious Fault Tolerant Control (FTC) Strategy Using The Hybrid Controller Structure To Establish Stable And Tracking Control With Two Faults Constrain In The Area Of Two Tank Canonical Non-Interacting Level Control System (TTCNILCS). Many Process Industries Use Canonical Tanks Because Of Its Varying Cross-Section Area Which Contributes Better Throughput From An Outlet For Different Material. Hence TTCNILCS Exhibit Nonlinear Behavior Because Of Its Changing Cross Section Area. The Problem Of Passive FTC (PFTC) For The TTCNILCS With The Unknown Actuator And Sensor Fault Is Investigated. The Actuator And Sensor Fault Is Assumed To Have No Traditional Affine Appearance Of The System And Control Input. Hybrid Controller (Neural Network Plus PID Controller) Is Used To Design PFTC And Implement To Achieve Satisfactory Steady-State Performance From TTCNILCS. The Effectiveness Of The Proposed Controller Validate From The Simulation Results And Errors Like MSE, ISE And ITAE.

Modelling and control of a Magneto-Rheological elastomer for impact reduction

This article presents the simulation analysis on the effectiveness of impact reduction control based magneto-rheological elastomer isolator device (MREID). The MREID is one of the impact isolator devices that produce controllable stiffness by controlling the input current supply to the device coil. In order to control the input current for MREID, a hybrid control structure combining the skyhook and active force control strategy (HYSAFC) is proposed. Firstly, the characteristics of MREID in squeeze mode are investigated systematically in order to establish the relationship between the supply input current to the subsequent force and impact energy within the MREID. The proposed control strategy is used for force tracking control in determining the amount of input current to be applied to the MREID. The desired input current is determined by a current generator that is developed using inverse ANFIS technique which will regulate the current amount based on the desired force and impact energy. The effectiveness of the actively controlled MREID is evaluated using MATLAB simulations by comparing the performance of the MREID controlled by skyhook control against a passive damper. It is shows that the proposed controller recorded better response compared to skyhook controller, thus improving the stability and the effectiveness in controlling the MRE isolator device.

Two-degree-of-freedom internal model position control and fuzzy fractional force control of nonlinear parallel robot

ABSTRACTThe paper proposes a novel method for the nonlinear redundantly actuated parallel robot based on force/position hybrid control structure. In order to solve the limitation of making a compromise for internal model controller, a two-DOF fractional order internal model control algorithm combining the internal model control principle and the fractional order theory is proposed for the position branch of the parallel robot redundantly actuated. This algorithm can realise the adjustment of the dynamic performance and anti-interference of 6PUS-UPU respectively. Aiming at the big force control error fractional order internal model, fuzzy control theory and the fractional order internal model controller are integrated into a new controller-fuzzy fractional order internal model(FFOIM) force control algorithm. Then Admas/Matlab simulation results demonstrate that the proposed algorithm can further reduce the driving force error of the system, and also retain the strong anti-interference of fractional order internal model controller.

A proton exchange membrane fuel cell with an airflow cooling system: Dynamics, validation and nonlinear control

This work synthesizes a reduced-order sliding mode observer-based sliding mode controller for a proton exchange membrane fuel cell system. This multivariable closed-loop system is dealt with two inputs (hydrogen fuel flow and cooling air flow rate) and two outputs (output voltage and stack temperature). For this, at first, we develop a nonlinear transient proton exchange membrane fuel cell model. This model is verified with the available experimental data. To maintain the fuel cell operating temperature, it is coupled with an airflow cooling fan. Then a nonlinear model-based control scheme is formulated that consists of sliding mode controller and reduced-order sliding mode observer. A special care is taken in control model against chattering response. Evaluating the sliding mode observer performance, it is integrated with sliding mode controller and the resulting hybrid control structure is compared with a traditional proportional integral controller. The nonlinear sliding mode observer-based controller shows its superiority over the proportional integral controller in rejecting the disturbance as well as tracking the set point.

A hybrid model predictive control for traffic flow stabilization and pollution reduction of freeways

In this work a control system is developed and analyzed for the suppression of moving jamwaves and the reduction of pollutant concentrations near motorways. The system is based on the second-order macroscopic freeway traffic model METANET, joined by an emission dispersion model, introduced in a previous work of the authors. For the control tasks dedicated controllers are designed, both using the nonlinear model predictive control method. The control objectives require a distinction in the utilized control measures, thus different controllers are designed and used in predefined control modes. The first mode of the controller is responsible for keeping pollutant concentrations below prescribed limits under stable conditions. The second mode of the controller is working in case of a shockwave threat, aiming for traffic stabilization. Between the control modes switching is based on an appropriate rule set that satisfies the stability of the controlled system. The hybrid controller structure is realized by a finite automata. A complex case study is presented for the evaluation of the suggested controller.

Data-Driven Robust Output Tracking Control for Gas Collector Pressure System of Coke Ovens

Disturbances, uncertainties, nonlinearity, couplings, and measurement disturbances exist extensively in the coke oven gas collector pressure system (GCPS) and may deteriorate tracking performance. In this paper, a practical method named data-driven robust output tracking control (DROTC) combining advantages of sliding-mode contr-ol (SMC) and data-driven control (DDC) is proposed for stable pressure control of gas collectors of coke ovens. Unlike the conventional DDC approach, the proposed controller is based on SMC framework, where a novel hybrid control structure and a new data-driven sliding surface are developed to facilitate the controller design. On one hand, the couplings, disturbances, and uncertainties are suppressed owing to the application of the SMC technique and the extended state observer. On the other hand, the stability of the DROTC system with bounded measurement disturbances could also be guaranteed by applying the DDC law. Moreover, the robustness could also be ensured once the sliding mode control system enters into the sliding mode. Finally, simulation and experimental results confirm the validity of the proposed control approach.

Modeling and optimal energy management of a power split hybrid electric vehicle

With the combination of engine and two electric machines, the power split device allows higher efficiency of the engine. The operation modes of a power split HEV are analyzed, and the system dynamic model is established for HEV forward simulation and controller design. Considering the fact that the operation modes of the HEV are event-driven and the system dynamics is continuous time-driven for each mode, the structure of the controller is built and described with the hybrid automaton control theory. In this control structure, the mode selection process is depicted by the finite state machine (FSM). The multi-mode switch controller is designed to realize power distribution. Furthermore, the vehicle mode operations are optimized, and the nonlinear model predictive control (NMPC) strategy is applied by implementing dynamic programming (DP) in the finite prediction horizon. Comparative simulation results demonstrate that the hybrid control structure is effective and feasible for HEV energy management design. The NMPC optimal strategy is superior in improving fuel economy.