Research

20 pages, 2804 KiB

Open AccessArticle

Behavior Prediction and Inverse Design for Self-Rotating Skipping Ropes Based on Random Forest and Neural Network

by Yunlong Qiu, Haiyang Wu, Yuntong Dai and Kai Li

Mathematics 2024, 12(7), 1019; https://0-doi-org.brum.beds.ac.uk/10.3390/math12071019 - 28 Mar 2024

Viewed by 415

Self-oscillatory systems have great utility in energy harvesting, engines, and actuators due to their ability to convert ambient energy directly into mechanical work. This characteristic makes their design and implementation highly valuable. Due to the complexity of the motion process and the simultaneous [...] Read more.

Self-oscillatory systems have great utility in energy harvesting, engines, and actuators due to their ability to convert ambient energy directly into mechanical work. This characteristic makes their design and implementation highly valuable. Due to the complexity of the motion process and the simultaneous influence of multiple parameters, computing self-oscillatory systems proves to be challenging, especially when conducting inverse parameter design. To simplify the computational process, a combined approach o0f Random Forest (RF) and Backpropagation Neural Network (BPNN) algorithms is employed. The example used is a self-rotating skipping rope made of liquid crystal elastomer (LCE) fiber and a mass block under illumination. Numerically solving the governing equations yields precise solutions for the rotation frequency of the LCE skipping rope under various system parameters. A database containing 138,240 sets of parameter conditions and their corresponding rotation frequencies is constructed to train the RF and BPNN models. The training outcomes indicate that RF and BPNN can accurately predict the self-rotating skipping rope frequency under various parameters, demonstrating high stability and computational efficiency. This approach allows us to discover the influences of distinct parameters on the rotation frequency as well. Moreover, it is capable of inverse design, meaning it can derive the corresponding desired parameter combination from a given rotation frequency. Through this study, a deeper understanding of the dynamic behavior of self-oscillatory systems is achieved, offering a new approach and theoretical foundation for their implementation and construction. Full article

(This article belongs to the Special Issue Advances in Dynamical System Modelling and Computer-Aided Design)

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24 pages, 2593 KiB

Open AccessArticle

Guaranteed H∞ Performance of Switched Systems with State Delays: A Novel Low-Conservative Constrained Model Predictive Control Strategy

by Yasser Falah Hassan, Mahmood Khalid Hadi Zarkani, Mohammed Jasim Alali, Haitham Daealhaq and Hicham Chaoui

Mathematics 2024, 12(2), 246; https://0-doi-org.brum.beds.ac.uk/10.3390/math12020246 - 11 Jan 2024

Viewed by 637

Abstract

In this paper, for the first time, a simultaneous design of a model predictive control plan and persistent dwell-time switching signal utilizing the conventional multiple Lyapunov–Krasovskii functional is proposed for linear delayed switched systems that are affected by physical constraints and exogenous disturbances. [...] Read more.

In this paper, for the first time, a simultaneous design of a model predictive control plan and persistent dwell-time switching signal utilizing the conventional multiple Lyapunov–Krasovskii functional is proposed for linear delayed switched systems that are affected by physical constraints and exogenous disturbances. The conventional multiple Lyapunov–Krasovskii functional with a ‘jump high’ condition is used as a step forward to reduce the strictness of constraints on controller design compared with the switched Lyapunov–Krasovskii functional. However, a dwell-time constraint is inflicted on the switching signal by the ‘jump-high’ condition. Therefore, to decrease the dwell-time limit, the persistent dwell-time structure is used and compared with other structures. Also, a new online framework is proposed to reduce the number of constraints on controller design at each time step. Moreover, for the first time, exogenous disturbances are considered in the procedure of MPC design for delayed switched systems, and non-weighted H∞ performance is ensured. The simulation outcome demonstrates the great performance of the suggested plan and its ability to asymptotically stabilize the switched system. Full article

(This article belongs to the Special Issue Advances in Dynamical System Modelling and Computer-Aided Design)

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18 pages, 2286 KiB

Open AccessArticle

Effluent Quality-Aware Event-Triggered Model Predictive Control for Wastewater Treatment Plants

by Guanting Li, Jing Zeng and Jinfeng Liu

Mathematics 2023, 11(18), 3912; https://0-doi-org.brum.beds.ac.uk/10.3390/math11183912 - 14 Sep 2023

Cited by 1 | Viewed by 652

Abstract

Wastewater treatment plants (WWTPs) are large-scale and nonlinear processes with tightly integrated operating units. The application of online optimization-based control strategies, such as model predictive control (MPC), to WWTPs generally faces high computational complexity. This paper proposes an event-triggered approach to address this [...] Read more.

Wastewater treatment plants (WWTPs) are large-scale and nonlinear processes with tightly integrated operating units. The application of online optimization-based control strategies, such as model predictive control (MPC), to WWTPs generally faces high computational complexity. This paper proposes an event-triggered approach to address this issue. The model predictive controller updates information and solves the optimization problem only when the corresponding triggered logic is satisfied. The triggered logic sets the maximum allowable deviation for the tracking variables. Moreover, to ensure system performance, the design of the event-triggered logic incorporates the effluent quality. By obtaining the optimal sequence for the effluent quality within the receding horizon of the MPC, the cumulative deviation between the predicted and desired effluent quality is analyzed to evaluate the performance within that horizon. Based on these two conditions, the need for adjusting control actions is determined. Even if the maximum allowable range for the tracking variables in the triggered logic design is set unreasonably, the consideration of effluent quality factors in the triggered conditions ensures good performance. Simulation results demonstrate an average reduction in computational effort of 25.49% under different weather conditions while simultaneously ensuring minimal impact on the effluent quality and total cost index and compliance with effluent discharge regulations. Furthermore, this method can be combined with other approaches to guarantee effluent quality while further reducing computation time and complexity. Full article

(This article belongs to the Special Issue Advances in Dynamical System Modelling and Computer-Aided Design)

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20 pages, 4924 KiB

Open AccessArticle

Dynamic Stability Measurement and Grey Relational Stability Sensitivity Analysis Methods for High-Speed Long-Span 4-1 Cable Robots

by Peng Liu, Haibo Tian, Xiangang Cao, Xuhui Zhang, Xinzhou Qiao and Yu Su

Mathematics 2022, 10(24), 4653; https://0-doi-org.brum.beds.ac.uk/10.3390/math10244653 - 08 Dec 2022

Cited by 2 | Viewed by 981

Abstract

High-speed long-span 4-1 cable robots (4-1HSLSCRs) have the characteristics of a simple structure, superior performance and easy control, and they can be used comprehensively in coal quality sampling, water quality monitoring, aerial panoramic photographing, etc. However, because of the high-speed movement of the [...] Read more.

High-speed long-span 4-1 cable robots (4-1HSLSCRs) have the characteristics of a simple structure, superior performance and easy control, and they can be used comprehensively in coal quality sampling, water quality monitoring, aerial panoramic photographing, etc. However, because of the high-speed movement of the end-effector and the unidirectional constraint property and nonlinear characteristics of the long-span cables, the dynamic stability of the 4-1HSLSCRs presents severe challenges. This paper, as a result, focuses on the two special problems of carrying out dynamic stability measurement and a stability sensitivity analysis for the 4-1HSLSCRs. First, a systematic approach that combines the cable tension, position and velocity of the end-platform based on both the dynamic model and the determinations of the cable tension is proposed for the high-speed robot, in which two cable tension and two position influencing factors are developed, respectively, whereas a velocity function is constructed, which represents the influence of the end-effector velocity on the dynamic stability of the 4-1HSLSCRs. Second, a grey relational analysis method for analyzing the dynamic stability of the 4-1HSLSCRs is developed, where the relationship between the dynamic stability of the 4-1HSLSCRs and the influencing factors (the position and velocity of the end-effector, as well as the cable tension) is investigated in detail. Finally, the measure approach and sensitivity analysis method for dynamic stability of 4-1HSLSCRs, namely, a camera robot with a high speed and long-span cables, is verified through simulation results. The results show that the large-span cable sags have significant effects on both the cable tensions and the dynamic stability of the camera robot, whereas the stability sensitivity evaluation results indicate that the effect of the stability sensitivity of the cable tensions on the dynamic stability of the camera robot is the greatest, followed by the velocity of the end-effector, and last is the position of the end-effector. Full article

(This article belongs to the Special Issue Advances in Dynamical System Modelling and Computer-Aided Design)

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19 pages, 20041 KiB

Open AccessArticle

A New Software-Based Optimization Technique for Embedded Latency Improvement of a Constrained MIMO MPC

by David Sotelo, Antonio Favela-Contreras, Alfonso Avila, Arturo Pinto, Francisco Beltran-Carbajal and Carlos Sotelo

Mathematics 2022, 10(15), 2571; https://0-doi-org.brum.beds.ac.uk/10.3390/math10152571 - 24 Jul 2022

Cited by 2 | Viewed by 1185

Abstract

Embedded controllers for multivariable processes have become a powerful tool in industrial implementations. Here, the Model Predictive Control offers higher performances than standard control methods. However, they face low computational resources, which reduces their processing capabilities. Based on pipelining concept, this paper presents [...] Read more.

Embedded controllers for multivariable processes have become a powerful tool in industrial implementations. Here, the Model Predictive Control offers higher performances than standard control methods. However, they face low computational resources, which reduces their processing capabilities. Based on pipelining concept, this paper presents a new embedded software-based implementation for a constrained Multi-Input-Multi-Output predictive control algorithm. The main goal of this work focuses on improving the timing performance and the resource usage of the control algorithm. Therefore, a profiling study of the baseline algorithm is developed, and the performance bottlenecks are identified. The functionality and effectiveness of the proposed implementation are validated in the NI myRIO 1900 platform using the simulation of a jet transport aircraft during cruise flight and a tape transport system. Numerical results for the study cases show that the latency and the processor usage are substantially reduced compared with the baseline algorithm,

4.6 \times

and

3.17 \times

respectively. Thus, efficient program execution is obtained which makes the proposed software-based implementation mainly suitable for embedded control systems. Full article

(This article belongs to the Special Issue Advances in Dynamical System Modelling and Computer-Aided Design)

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16 pages, 848 KiB

Open AccessArticle

Quasi-Linear Parameter Varying Modeling and Control of an Electromechanical Clutch Actuator

by Tamás Bécsi

Mathematics 2022, 10(9), 1473; https://0-doi-org.brum.beds.ac.uk/10.3390/math10091473 - 27 Apr 2022

Cited by 2 | Viewed by 1589

Abstract

The paper presents the modeling and control design of an electromechanical heavy-duty clutch actuator using gain-scheduled MPC and grid-based Linear Parameter Varying approaches. First, the nonlinear model of the electromechanical actuator is presented, then a third order quasi-Linear Parameter Varying representation of the [...] Read more.

The paper presents the modeling and control design of an electromechanical heavy-duty clutch actuator using gain-scheduled MPC and grid-based Linear Parameter Varying approaches. First, the nonlinear model of the electromechanical actuator is presented, then a third order quasi-Linear Parameter Varying representation of the system is derived, which takes the nonlinear characteristic of the diaphragm spring into account. Using the control-oriented model, a Linear Parameter Varying controller and a gain-scheduled Model Predictive Controller are designed, the latter of which serves as benchmark. The controllers have been implemented and tested in a model in the loop environment, where their performances have been compared concerning their rise-time, steady-state error, over-and undershoots, and robustness to the changes of the touch-point. The validation results show that the difference between the model predictive controllers is negligible in most cases, and they surpass the linear parameter varying controller regarding the rise-time. On the other hand, the linear parameter varying approach has proven to be much more robust to the load force and the touch-point changes while also performing better concerning the under- and overshoots. Therefore, it is more suitable to achieve the position control of the actuator. Full article

(This article belongs to the Special Issue Advances in Dynamical System Modelling and Computer-Aided Design)

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12 pages, 4048 KiB

Open AccessArticle

The Influences of the Hyperbolic Two-Temperatures Theory on Waves Propagation in a Semiconductor Material Containing Spherical Cavity

by Aatef Hobiny, Ibrahim Abbas and Marin Marin

Mathematics 2022, 10(1), 121; https://0-doi-org.brum.beds.ac.uk/10.3390/math10010121 - 01 Jan 2022

Cited by 8 | Viewed by 1231

Abstract

This article focuses on the study of redial displacement, the carrier density, the conductive and thermodynamic temperatures and the stresses in a semiconductor medium with a spherical hole. This study deals with photo-thermoelastic interactions in a semiconductor material containing a spherical cavity. The [...] Read more.

This article focuses on the study of redial displacement, the carrier density, the conductive and thermodynamic temperatures and the stresses in a semiconductor medium with a spherical hole. This study deals with photo-thermoelastic interactions in a semiconductor material containing a spherical cavity. The new hyperbolic theory of two temperatures with one-time delay is used. The internal surface of the cavity is constrained and the density of carriers is photogenerated by a heat flux at the exponentially decreasing pulse boundaries. The analytical solutions by the eigenvalues approach under the Laplace transformation approaches are used to obtain the solution of the problem and the inversion of the Laplace transformations is performed numerically. Numerical results for semiconductor materials are presented graphically and discussed to show the variations of physical quantities under the present model. Full article

(This article belongs to the Special Issue Advances in Dynamical System Modelling and Computer-Aided Design)

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22 pages, 9214 KiB

Open AccessArticle

Generative Design for Dimensioning of Retaining Walls

by Gabriel Díaz, Rodrigo F. Herrera, Felipe Muñoz-La Rivera and Edison Atencio

Mathematics 2021, 9(16), 1918; https://0-doi-org.brum.beds.ac.uk/10.3390/math9161918 - 12 Aug 2021

Cited by 2 | Viewed by 2862

Abstract

The design of retaining walls follows a classic structure. The engineer proposes certain dimensions that will be modified until they comply with the regulatory and site restrictions presented by the project. This is an iterative process that can be optimized through a new [...] Read more.

The design of retaining walls follows a classic structure. The engineer proposes certain dimensions that will be modified until they comply with the regulatory and site restrictions presented by the project. This is an iterative process that can be optimized through a new method called generative design. The designer codes the characteristics and restrictions of the project so that the system creates the most appropriate solutions to the problem presented. In this research, a computer program was created to build the dimensions of retaining walls using generative design. For this purpose, Design Science Research (DSR) was used, complemented with the incremental software development method. A program that delivers multiple retaining wall design alternatives in a short time was constructed. The evaluation of this program was performed through usability tests, giving as main perceptions the program’s ease of use and the time savings concerning the traditional design. Full article

(This article belongs to the Special Issue Advances in Dynamical System Modelling and Computer-Aided Design)

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