2,662 results on '"robust control"'
Search Results
2. Robust Global Trajectory Tracking for Underactuated VTOL Aerial Vehicles Using Inner-Outer Loop Control Paradigms
- Author
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Naldi, Roberto, Furci, Michele, Sanfelice, Ricardo G, and Marconi, Lorenzo
- Subjects
Aerial robotics ,hybrid control ,interconnected systems ,nonlinear control ,robust control ,Applied Mathematics ,Electrical and Electronic Engineering ,Mechanical Engineering ,Industrial Engineering & Automation - Abstract
This paper proposes a feedback control strategy to let the dynamics of a class of under-Actuated vertical take-off and landing (VTOL) aerial vehicle tracking a desired position and attitude trajectory globally with respect to the initial conditions. The proposed feedback controller is derived following an inner-outer loop control paradigm, namely by considering the attitude, which is governed by means of a hybrid controller so as to overcome the well-known topological constraints, serving as a virtual input to stabilize the aircraft position. Two different approaches, the first one obtained by assuming perfect knowledge of the vehicle dynamics and the second one obtained by considering uncertainties and exogenous disturbances, are proposed and compared by analyzing the interconnection between the hybrid attitude and the continuous-Time position closed-loop subsystems. The effectiveness of the obtained results is demonstrated by means of simulations and experiments using a miniature quadrotor prototype.
- Published
- 2017
3. Robust Path-Following Control for High-Altitude Long-Endurance Aircraft
- Author
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Weiser, Christian, Ossmann, Daniel, and Pfifer, Harald
- Subjects
Space and Planetary Science ,Control and Systems Engineering ,DLR HAP ,Autopilot ,Applied Mathematics ,HALE ,Aerospace Engineering ,Electrical and Electronic Engineering ,Robust Control - Published
- 2023
4. Robust Control Pulses Design for Electron Shuttling in Solid-State Devices
- Author
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Zhang, Jun, Greenman, Loren, Deng, Xiaotian, and Whaley, K Birgitta
- Subjects
Electron shuttling ,pulses design ,robust control ,Applied Mathematics ,Electrical and Electronic Engineering ,Industrial Engineering & Automation - Abstract
In this brief, we study robust pulse design for electron shuttling in solid-state devices. This is crucial for many practical applications of coherent quantum mechanical systems. Our objective is to design control pulses that can transport an electron along a chain of donors and that also make this process robust to parameter uncertainties. We formulate this problem here as a set of optimal control problems and derive explicit expressions for the gradients of the aggregate transfer fidelity. Numerical results for a donor chain of ionized phosphorus atoms in bulk silicon demonstrate the efficacy of our algorithm.
- Published
- 2014
5. Feedback control of charged ideal fluids.
- Author
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Hochgerner, Simon
- Subjects
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SHEAR flow , *ROBUST control , *APPLIED mathematics , *FLUIDS , *MAGNETIC fields - Abstract
The theory of controlled mechanical systems of Bloch et al (2001 IEEE Trans. Control Syst. Technol. 45 2253–70; Bloch et al 2001 Int. J. Robust Nonlinear Control 11 191–214; Bloch et al 1992 Automatica 28 745–56; Bloch et al 1997 Current and Future Directions in Applied Mathematics) and Krishnaprasad P S (1985 Nonlinear Anal. Theor. Methods Appl. 9 1011–35) is extended to the case of ideal incompressible fluids consisting of charged particles in the presence of an external magnetic field. The resulting control is of feedback type and depends on the Eulerian state of the controlled system. Moreover, the control is set up so that the corresponding closed loop equations are Lie–Poisson. This implies that the energy–momentum method of Arnold V (1966 Ann. Inst. Fourier 16 319–61) and Holm et al (1985 Phys. Rep. 123 1–116) can be used to find a stabilizing control. As an example the case of planar parallel shear flow with an inflection point is treated. A state dependent feedback control is constructed which stabilizes the system for an arbitrarily long channel. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
6. Modeling and control of an invasive mechanical ventilation system using the active disturbances rejection control structure
- Author
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David I. Rosas Almeida, Armando Cantú Cárdenas, Iván Olaf Hernández Fuentes, Rosa Citlalli Anguiano Cota, Laura Ocotlán Orea León, David Rafael Cañez Martínez, and Angélica María Martínez Contreras
- Subjects
Ventilators, Mechanical ,Critical Care ,Applied Mathematics ,Robust control ,COVID-19 ,Mechanical ventilator ,Models, Theoretical ,Identification of disturbances ,Respiration, Artificial ,Computer Science Applications ,Control and Systems Engineering ,Humans ,Electrical and Electronic Engineering ,Instrumentation ,Research Article - Abstract
We propose a mandatory invasive mechanical ventilator prototype for severe COVID-19 patients with volume and pressure control operation modes. This system comprises basic pneumatic elements and sensors. Its performance is similar to commercial equipment, and it presents robustness to external disturbances and parametric uncertainties. To develop a control strategy, we propose a mathematical model with a variable structure that incorporates the dead zone phenomenon of the proportional valve, and considers external disturbances and parametric uncertainties. Based on this model, we propose a global control strategy that is based on pressure and flow regulation controllers, which use the active disturbances rejection control structure (ADRC). In this strategy, we propose robust state observers to estimate disturbances and the signals necessary for implementing the controllers. We illustrate the performance of the prototype and the control strategy through numerical simulations and experiments. We also compare its performance with PID controllers. These results corroborate its effectiveness and the possibility of its application in invasive mechanical ventilators with a simple structure, which can significantly help critical care of COVID-19 inpatients.
- Published
- 2022
7. Stackelberg-Game-Oriented Optimal Control for Bounded Constrained Mechanical Systems: A Fuzzy Evidence-Theoretic Approach
- Author
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Zhijun Li, Yunjun Zheng, Han Zhao, Chunsheng He, and Jinchuan Zheng
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Mathematical optimization ,Optimization problem ,Computer science ,Applied Mathematics ,Optimal control ,Fuzzy logic ,Constraint (information theory) ,Computational Theory and Mathematics ,Artificial Intelligence ,Control and Systems Engineering ,Bounded function ,Stackelberg competition ,Uniform boundedness ,Robust control - Abstract
This paper proposes a novel Stackelberg game-oriented optimal control approach to address the bounded constraint-following control problem for uncertain mechanical systems. First, the uncertainties (possibly fast time-varying) in the system are assumed to be bounded with an unknown boundary which lies in a specified fuzzy evidence number. In practical engineering, bounded system performance is always demanded, such as the inequality constraint. A diffeomorphism transformation approach is proposed to transform the constrained system into a restructured one satisfying the bounded constraint. Second, we propose an adaptive robust control oriented by the constraint-following control to render the restructured system to follow the specified constraints accurately with deterministic performance (guaranteeing uniform boundedness and uniform ultimate boundedness). The self-adjusting adaptive law (leakage-type) can compensate for the uncertainties and avoid overcompensation. Third, a Stackelberg game-oriented optimization approach is proposed to obtain the optimal control parameters based on the fuzzy evidence theory. In the optimization approach, the two control parameters, are considered as two players with respective cost functions related to system performance and control cost. Furthermore, the optimization problem is solved by obtaining the Stackelberg strategy, which is proved to exist in analytic form. Ultimately, the permanent magnet synchronous linear motor system simulation is presented to show the design process and the excellent performance of the proposed optimal control scheme.
- Published
- 2022
8. Geometric-based prescribed performance control for unmanned aerial manipulator system under model uncertainties and external disturbances
- Author
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Weiwei Zhan, Zhiqiang Miao, Yaonan Wang, Chen Yanjie, He Bingwei, and Hui Zhang
- Subjects
Lyapunov stability ,Adaptive control ,Computer science ,Underactuation ,Applied Mathematics ,Thrust ,Computer Science Applications ,Control and Systems Engineering ,Control theory ,Drag ,Trajectory ,Transient (oscillation) ,Electrical and Electronic Engineering ,Robust control ,Instrumentation - Abstract
In this paper, a robust control strategy with a cascade structure is designed for the underactuated unmanned aerial manipulator (UAM) to perform favorable trajectory tracking, in the presence of model uncertainties and time-varying external disturbances (e.g. wind drag). In the position loop, a geometric distance is adopted as the criterion for the thrust design. Besides, both the model uncertainties and external disturbances are compensated by employing a robust term. In the attitude loop, the prescribed performance guarantees are enforced in the controller design to standardize transient performance on attitude errors. In particular, just relying on the necessary feedback states, an auxiliary system, the adaptive control technique, and the disturbance observer are respectively designed to estimate the model uncertainties and external disturbances. Through the Lyapunov stability theory analysis, the proposed approach based on a geometric distance can effectively track the desired trajectory. The results of the comparative simulations study demonstrate the effectiveness and advantages of the proposed approach.
- Published
- 2022
9. Controller Design for Affine Nonlinear System Based on Constructing Optimization T–S Fuzzy Model and Disturbance Reconstruction
- Author
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Yuhang Fu and Fanglai Zhu
- Subjects
Affine nonlinear system ,Disturbance (geology) ,Computational Theory and Mathematics ,Observer (quantum physics) ,Artificial Intelligence ,Control and Systems Engineering ,Control theory ,Computer science ,Applied Mathematics ,Fuzzy model ,Interval (mathematics) ,Robust control ,Compensation (engineering) - Abstract
Affine nonlinear systems are special kinds of non-linear systems, and they can represent many practical systems. Dealing with affine nonlinear system based on T-S fuzzy model has drawn much attention in literature recently. In this paper, a robust control method is proposed for affine nonlinear system with disturbance based on T-S fuzzy model. First, an optimization T-S fuzzy model is constructed focusing on optimizing the parameters of the weight functions by using differential evolution algorithm (DEA). Second, in order to reconstruct the disturbance, an interval observer is designed for the affine nonlinear system, and then a novelty disturbance reconstruction method based on the interval observer is developed. The disturbance reconstruction value can asymptotically approach the actual disturbance value, and furthermore, it decouples the control input. Third, by taking the optimization T-S fuzzy model as design model and by introducing the reconstruction of disturbance into controller, a feedback robust controller with disturbance compensation is designed to stabilize the affine nonlinear system. Finally, a simulation example of the crane model is given and some comparisons are provided to verify the effectiveness and show the advantages of the proposed method.
- Published
- 2022
10. Equivalent-input-disturbance-based robust control of drilling trajectory with weight-on-bit uncertainty in directional drilling
- Author
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Luefeng Chen, Xuzhi Lai, Chengda Lu, Min Wu, and Zhen Cai
- Subjects
Observer (quantum physics) ,Computer science ,Applied Mathematics ,Directional drilling ,Drilling ,Computer Science Applications ,Azimuth ,Control and Systems Engineering ,Control theory ,Weight on bit ,Trajectory ,Electrical and Electronic Engineering ,Bottom hole assembly ,Robust control ,Instrumentation - Abstract
Weight-on-Bit is of vital importance to the drilling trajectory orientation in directional drilling. This paper concerns robust control of drilling trajectory with weight-on-bit uncertainty for the directional drilling process. The objective is to develop an equivalent-input-disturbance-based trajectory control scheme such that the drilling trajectory is precisely controlled by suppressing the fluctuations of weight-on-bit. The motion orientation of both the drill bit and a series of stabilizers is used to describe the evolution process of the drilling trajectory. A state-space model with weight-on-bit uncertainty is derived from the evolution equation through a variable transformation. An equivalent-input-disturbance-based trajectory control system is designed, and two control loops are to track and control the trajectory inclination and azimuth, respectively. Two internal models track the trajectory inclination and azimuth respectively to elevate the control accuracy in the trajectory system. Two observer models combined with two low-pass filters estimate the trajectory inclination and azimuth by measuring the bottom hole assembly’s inclination and azimuth. Some sufficient conditions are derived using linear-matrix-inequalities to obtain the control parameters by considering a reasonable fluctuation range of weight-on-bit. Finally, the control effects in the build-up and horizontal section of the drilling trajectory illustrate the proposed approach’s validity.
- Published
- 2022
11. Design and Optimization of Robust Path Tracking Control for Autonomous Vehicles With Fuzzy Uncertainty
- Author
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Jin Huang, Zeyu Yang, Yang Diange, and Zhihua Zhong
- Subjects
Scheme (programming language) ,Computer science ,Applied Mathematics ,Control (management) ,Fuzzy set ,Fuzzy control system ,Kinematics ,Fuzzy logic ,Computational Theory and Mathematics ,Artificial Intelligence ,Control and Systems Engineering ,Control theory ,Uniform boundedness ,Robust control ,computer ,computer.programming_language - Abstract
Uncertainty is a major concern in vehicle path tracking control design. The coefficients of the uncertainty bound are unknown. They are assumed to lie within prescribed fuzzy sets. First, based on the path tracking kinematic model, this paper innovatively formulates the vehicle path tracking task as a constraint-following problem. Second, we put forward a deterministic adaptive robust control law with a tunable parameter to ensure the uniform boundedness and ultimate uniform boundedness of the closed-loop system. Third, an optimal scheme for the tunable parameter is proposed based on the fuzzy uncertainty. The resulting optimal robust control (ORC) minimizes a comprehensive fuzzy performance index that involves the fuzzy system performance and the control cost. The results of the CarSim-Simulink co-simulation and the Hardware-in-loop (HIL) experiment together show that the proposed optimal robust control exhibits a superior path tracking performance.
- Published
- 2022
12. Finite-time anti-saturation control for Euler–Lagrange systems with actuator failures
- Author
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Sai Zhang, Yushan He, Zhongchao Deng, Bo Wang, and Bing Huang
- Subjects
0209 industrial biotechnology ,Adaptive control ,Computer science ,Applied Mathematics ,020208 electrical & electronic engineering ,Hyperbolic function ,02 engineering and technology ,Computer Science Applications ,020901 industrial engineering & automation ,Control and Systems Engineering ,Robustness (computer science) ,Control theory ,Bounded function ,0202 electrical engineering, electronic engineering, information engineering ,sort ,Electrical and Electronic Engineering ,Robust control ,Actuator ,Instrumentation - Abstract
This paper provides two bounded finite-time control strategies for the stabilization problem of Euler-Lagrange (EL) systems exposed to actuator failures. By the combination of sliding mode technology and adaptive method, two control architectures have been constructed such that the system states will be forced towards the origin within finite time. The first controller is applicable in the case that exact information of the external disturbance and actuator faults are available. However, it still remains challenging for designers to obtain this sort of information in engineering practice. On account for this, adaptive laws are applied in the second controller to obtain estimations about the unknown parameters, thus ensuring desirable fault-tolerance ability and robustness for the EL systems. By resorting to the properties of EL systems and hyperbolic tangent functions, outputs of these two controllers will be proven to be bounded. Simulation examples are presented to manifest the validity of the developed algorithms.
- Published
- 2022
13. Prescribed performance model-free adaptive sliding mode control of a shape memory alloy actuated system
- Author
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Zhirui Zhao, Lina Hao, and Mingfang Liu
- Subjects
0209 industrial biotechnology ,Adaptive control ,Computer science ,Applied Mathematics ,020208 electrical & electronic engineering ,PID controller ,02 engineering and technology ,Sliding mode control ,Computer Science Applications ,Tracking error ,Nonlinear system ,020901 industrial engineering & automation ,Transformation (function) ,Control and Systems Engineering ,Control theory ,Linearization ,0202 electrical engineering, electronic engineering, information engineering ,Electrical and Electronic Engineering ,Robust control ,Instrumentation - Abstract
This paper concentrates on a simple and robust control method for the discrete time nonlinear systems to fulfill the requirement of predefined accuracy. A sliding mode control method is designed by introducing equivalent dynamic linearization technique according to the input/output (I/O) information merely. A square-root type error transformation method is presented for the tracking error to be restricted within a preassigned zone. The performance of presented control method is demonstrated through experiments on a nonlinear system. Experiment results show that the presented control method has a superior tracking accuracy compared with PID controller and model-free adaptive control (MFAC).
- Published
- 2022
14. Gust Load Alleviation Using Reduced-Order Aeroelastic Models and Observer-Based Robust Control
- Author
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Alex dos Reis de Souza, Pierre Vuillemin, Charles Poussot-Vassal, and David Quero
- Subjects
Space and Planetary Science ,Control and Systems Engineering ,Applied Mathematics ,Aerospace Engineering ,Electrical and Electronic Engineering ,Aeroelasticity ,robust control ,gust load alleviation - Published
- 2023
15. Identification and control of dynamical systems using different architectures of recurrent fuzzy system.
- Author
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Dass, Anuli and Srivastava, Smriti
- Subjects
DYNAMICAL systems ,FUZZY systems ,ROBUST control ,APPLIED mathematics ,SYSTEM analysis - Abstract
Abstract Fuzzy logic based systems are very widely used for modeling and control of complex non-linear, plants. Fuzzy systems require the knowledge about the structure of the dynamic plant in order to achieve fruitful results. Recurrent Fuzzy systems (RFS) are a variation of fuzzy systems and have the ability to model and control dynamic plants without using the information about the structure of the plant. This paper presents identification and control of non-linear dynamical systems using two different architectures of recurrent fuzzy system (RFS). It highlights the importance of RFS over the conventional type-1 fuzzy based system. The objective of system identification as well as control has been achieved using both the architectures of RFS and the simulation results clearly show their efficiency. This paper also highlights yet another advantage of RFS over the conventional type-1 fuzzy systems which comes into light when dealing with higher order systems. The paper explains how the computational complexity can be greatly reduced by using RFS for higher order dynamical systems. A comparative analysis between the conventional type-1 fuzzy system and the two recurrent fuzzy systems has also been performed. Highlights • Identification and Control without the knowledge about the order and structure of the plants using 2 different recurrent fuzzy structures. • A remarkable reduction in the complexity as compared to conventional fuzzy systems when dealing with higher order systems. • Checking the robustness of the discussed recurrent fuzzy structures against parameter perturbation as well as external disturbances. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
16. Accurate, robust and harmonized implementation of morpho-functional imaging in treatment planning for personalized radiotherapy.
- Author
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Jiménez-Ortega, Elisa, Ureba, Ana, Baeza, José Antonio, Barbeiro, Ana Rita, Balcerzyk, Marcin, Parrado-Gallego, Ángel, Wals-Zurita, Amadeo, García-Gómez, Francisco Javier, and Leal, Antonio
- Subjects
- *
RADIOTHERAPY treatment planning , *POSITRON emission tomography , *RADIATION doses , *IMAGE processing , *LINEAR programming , *ROBUST control - Abstract
In this work we present a methodology able to use harmonized PET/CT imaging in dose painting by number (DPBN) approach by means of a robust and accurate treatment planning system. Image processing and treatment planning were performed by using a Matlab-based platform, called CARMEN, in which a full Monte Carlo simulation is included. Linear programming formulation was developed for a voxel-by-voxel robust optimization and a specific direct aperture optimization was designed for an efficient adaptive radiotherapy implementation. DPBN approach with our methodology was tested to reduce the uncertainties associated with both, the absolute value and the relative value of the information in the functional image. For the same H&N case, a single robust treatment was planned for dose prescription maps corresponding to standardized uptake value distributions from two different image reconstruction protocols: One to fulfill EARL accreditation for harmonization of [18F]FDG PET/CT image, and the other one to use the highest available spatial resolution. Also, a robust treatment was planned to fulfill dose prescription maps corresponding to both approaches, the dose painting by contour based on volumes and our voxel-by-voxel DPBN. Adaptive planning was also carried out to check the suitability of our proposal. Different plans showed robustness to cover a range of scenarios for implementation of harmonizing strategies by using the highest available resolution. Also, robustness associated to discretization level of dose prescription according to the use of contours or numbers was achieved. All plans showed excellent quality index histogram and quality factors below 2%. Efficient solution for adaptive radiotherapy based directly on changes in functional image was obtained. We proved that by using voxel-by-voxel DPBN approach it is possible to overcome typical drawbacks linked to PET/CT images, providing to the clinical specialist confidence enough for routinely implementation of functional imaging for personalized radiotherapy. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
17. Non-fragile state estimation for memristive cellular neural networks with proportional delay
- Author
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G. Nagamani and A. Karnan
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Lyapunov stability ,Numerical Analysis ,General Computer Science ,Computer science ,Applied Mathematics ,Estimator ,Memristor ,Stability (probability) ,Theoretical Computer Science ,law.invention ,Matrix (mathematics) ,Control theory ,law ,Modeling and Simulation ,Cellular neural network ,Robust control ,MATLAB ,computer ,computer.programming_language - Abstract
This paper focuses on modeling a non-fragile state estimator for a class of memristive cellular neural networks (MCNNs) with proportional delay. Due to the state transition characteristics of memristor, the parameters of MCNNs are state-dependent. A discontinuous robust control scheme is applied to address such parameters issue. Using this control scheme, we have derived sufficient conditions to ensure the existence of a non-fragile state estimator for the supposed system. Through the Lyapunov stability analysis and matrix-based inequality techniques, delay-dependent stability criteria are obtained in the form of linear matrix inequalities (LMIs), which shows the asymptotic stableness of the prescribed error system under the consideration of all possible gain variations. Besides, the control gain components are obtained by solving the resulting LMIs using some available MATLAB algorithms. Lastly, to facilitate the efficacy of the proposed estimator design, numerical simulations are examined.
- Published
- 2022
18. A fuzzy neural network-based fractional-order Lyapunov-based robust control strategy for exoskeleton robots: Application in upper-limb rehabilitation
- Author
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Amir Razzaghian
- Subjects
Lyapunov function ,Lyapunov stability ,Numerical Analysis ,General Computer Science ,Computer science ,Applied Mathematics ,Terminal sliding mode ,Theoretical Computer Science ,Exoskeleton ,symbols.namesake ,Control theory ,Robustness (computer science) ,Modeling and Simulation ,Control system ,symbols ,Robust control - Abstract
The paper investigates a novel fractional-order Lyapunov-based robust controller based on a fuzzy neural network (FNN) compensator for exoskeleton robotic systems. First, a finite-time fractional-order nonsingular fast terminal sliding mode control (FONFTSMC) method is designed. Second, a FNN algorithm is constructed to approximate the model uncertainty and external disturbances. Then, finite-time stability of the closed-loop control system is proved using Lyapunov stability theorem and adaptive law is derived through it. The proposed fuzzy neural network-based FONFTSMC (FNN-FONFTSMC) guarantees finite-time convergence and robustness against uncertainties for the exoskeleton robots trajectory tracking. Finally, to illustrate the effectiveness of the proposed control strategy, an upper-limb exoskeleton robot is provided as a case study in rehabilitation. The simulation results confirm the superiority of the proposed control method.
- Published
- 2022
19. Robust optimization control for turbidity process with large inertia and time-delay in waterworks
- Author
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Qinruo Wang, Zhang Hui, Liu Jianqi, Guobo Xiang, and Chen Zicong
- Subjects
0209 industrial biotechnology ,Computer science ,Applied Mathematics ,media_common.quotation_subject ,020208 electrical & electronic engineering ,Stability (learning theory) ,Robust optimization ,02 engineering and technology ,Optimal control ,Inertia ,Computer Science Applications ,020901 industrial engineering & automation ,Control and Systems Engineering ,Robustness (computer science) ,Control theory ,0202 electrical engineering, electronic engineering, information engineering ,Computer Simulation ,State observer ,Pruning (decision trees) ,Electrical and Electronic Engineering ,Robust control ,Instrumentation ,Algorithms ,media_common - Abstract
To address the difficulty of optimizing turbidity process with large inertia and long time delay, a twice-optimal control and construction pruning (TOCCP) strategy is proposed, which can be used to improve the fast stability and strong robustness of industrial process. The new approach owns the advantages of twice optimal control (TOC) and construction pruning (CP) method. The TOC constructs an infinite-dimensional state observer of the system, which can eliminate the influence of time delay on the system. The CP is adopted to improve the mid-band damping of the open-loop frequency characteristics to improve the robustness of the system. Moreover, an exhaustive algorithm is designed to find the optimal time scale, the most important parameter for adjusting the system response speed. In addition, the influences of different parameter changes on the robustness of the system are analyzed, and a practical parameter tuning formula is provided. Simulation-based comparisons of TOCCP and the other two algorithms were made. The results show that the system optimized by TOCCP has strong robustness, especially in disturbances rejection and set-point tracking. Moreover, TOCCP is practical and easily implemented to set parameters, providing guidelines for industrial application of large inertia and time-delay systems.
- Published
- 2022
20. Assessing robustness against potential publication bias in Activation Likelihood Estimation (ALE) meta-analyses for fMRI.
- Author
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Acar, Freya, Seurinck, Ruth, Eickhoff, Simon B., and Moerkerke, Beatrijs
- Subjects
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NEUROSCIENCES , *COMPUTER algorithms , *ROBUST control , *LIFE sciences , *META-analysis - Abstract
The importance of integrating research findings is incontrovertible and procedures for coordinate-based meta-analysis (CBMA) such as Activation Likelihood Estimation (ALE) have become a popular approach to combine results of fMRI studies when only peaks of activation are reported. As meta-analytical findings help building cumulative knowledge and guide future research, not only the quality of such analyses but also the way conclusions are drawn is extremely important. Like classical meta-analyses, coordinate-based meta-analyses can be subject to different forms of publication bias which may impact results and invalidate findings. The file drawer problem refers to the problem where studies fail to get published because they do not obtain anticipated results (e.g. due to lack of statistical significance). To enable assessing the stability of meta-analytical results and determine their robustness against the potential presence of the file drawer problem, we present an algorithm to determine the number of noise studies that can be added to an existing ALE fMRI meta-analysis before spatial convergence of reported activation peaks over studies in specific regions is no longer statistically significant. While methods to gain insight into the validity and limitations of results exist for other coordinate-based meta-analysis toolboxes, such as Galbraith plots for Multilevel Kernel Density Analysis (MKDA) and funnel plots and egger tests for seed-based d mapping, this procedure is the first to assess robustness against potential publication bias for the ALE algorithm. The method assists in interpreting meta-analytical results with the appropriate caution by looking how stable results remain in the presence of unreported information that may differ systematically from the information that is included. At the same time, the procedure provides further insight into the number of studies that drive the meta-analytical results. We illustrate the procedure through an example and test the effect of several parameters through extensive simulations. Code to generate noise studies is made freely available which enables users to easily use the algorithm when interpreting their results. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
21. Enhancing the robustness of recommender systems against spammers.
- Author
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Zhang, Chengjun, Liu, Jin, Qu, Yanzhen, Han, Tianqi, Ge, Xujun, and Zeng, An
- Subjects
- *
RECOMMENDER systems , *INFORMATION science , *ROBUST control , *COMPUTER algorithms , *COMPUTER science - Abstract
The accuracy and diversity of recommendation algorithms have always been the research hotspot of recommender systems. A good recommender system should not only have high accuracy and diversity, but also have adequate robustness against spammer attacks. However, the issue of recommendation robustness has received relatively little attention in the literature. In this paper, we systematically study the influences of different spammer behaviors on the recommendation results in various recommendation algorithms. We further propose an improved algorithm by incorporating the inner-similarity of user’s purchased items in the classic KNN approach. The new algorithm effectively enhances the robustness against spammer attacks and thus outperforms traditional algorithms in recommendation accuracy and diversity when spammers exist in the online commercial systems. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
22. Parameter extraction method for the twisted pair cable with rectangular connectors.
- Author
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Fang, Wei, Ren, Yongfeng, Liu, Xin, Jiao, Xinquan, and Chu, Chengqun
- Subjects
- *
CABLES , *INFORMATION sharing , *HYPERBOLIC functions , *MATERIALS science , *ROBUST control - Abstract
Cables play an important role in transmitting energy and information. In this article, in order to obtain the S-parameters of the special twisted pair cable with rectangular connectors, a de-embedding method of the transmission matrix is proposed to deal with the two adapters ends of the cable. According to the frequency-dependent RLGC(f) model, the cable characteristics are extracted in the frequency range of 10 MHz to 200 MHz through conventional and modified methods respectively. The frequency-domain analysis shows that the inherent capacity of modified method can decrease the errors especially due to the discontinuities of hyperbolic functions. This research supplies an advantageous modelling approach for the cable to improve its robustness against disturbances in the S-parameters measurement that cannot be decreased with the calibration procedure. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
23. Probabilistic Robustness Analysis of Uncertain LTV Systems in Linear Fractional Representation
- Author
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Evangelisti, Luca and Pfifer, Harald
- Subjects
Control and Optimization ,Polynomial chaos ,Stochastic process ,Orthographic projection ,Robust control ,Hilbert space ,time-varying systems ,Projection (linear algebra) ,Standard deviation ,symbols.namesake ,Generalized Fourier series ,uncertain systems ,Control and Systems Engineering ,symbols ,Applied mathematics ,Galerkin method ,Mathematics - Abstract
This letter quantifies the effect of random model uncertainty on finite horizon linear time-varying (LTV) systems. Mean and standard deviation field are approximated with high accuracy and efficiency by a Hilbert space technique called polynomial chaos expansion (PCE). The deterministic expansion coefficients of the generalized Fourier series are determined via orthogonal projection, also known as Galerkin projection. We propose the projection of uncertain systems in linear fractional representation (LFR), which can have computational benefits. The technique is benchmarked on a two-link robotic manipulator.
- Published
- 2022
24. Possibility-Based Robust Control for Fuzzy Mechanical Systems
- Author
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Ye-Hwa Chen, Hui Yin, and Jin Huang
- Subjects
Lyapunov stability ,Nonholonomic system ,Underactuation ,Computer science ,Holonomic ,Applied Mathematics ,Fuzzy set ,02 engineering and technology ,Fuzzy logic ,Computational Theory and Mathematics ,Artificial Intelligence ,Control and Systems Engineering ,Control theory ,0202 electrical engineering, electronic engineering, information engineering ,020201 artificial intelligence & image processing ,Robust control ,Possibility theory - Abstract
This study proposes a new robust control design framework for uncertain mechanical systems, which may be fullyactuated or underactuated. The uncertainty is (possibly fast) time-varying, lies in prescribed fuzzy sets (hence fuzzy mechanical systems), and may be unbounded. The control goal is formulated as servo constraints (hence constraint-following control), which may be holonomic or nonholonomic. We introduce the possibility theory into the Lyapunov stability analysis (LSA), proposing possibilitybased Lyapunov stability analysis (PBLSA), which allows a maximum failure possibility (generally small) prescribed by designers. It can be viewed as a generalization of the conventional LSA, and the resultant performance is interpreted in the context of possibility. By the PBLSA, a class of robust constraint-following controls that is not IF-THEN heuristic rules-based is proposed, which renders approximate constraint-following for the system performance with a prescribed maximal failure possibility. Optimal design of a control parameter considering both system performance and control cost is investigated. The benefits of the proposed design framework are discussed and simulations on two applications are given for demonstrations.
- Published
- 2021
25. Adaptive Fuzzy Risk-Sensitive Control for Stochastic Strict-Feedback Nonlinear Systems With Unknown Uncertainties
- Author
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Kangkang Sun, Jianbin Qiu, Min Ma, and Tong Wang
- Subjects
Computer science ,Applied Mathematics ,Control (management) ,MathematicsofComputing_NUMERICALANALYSIS ,Stability (learning theory) ,Hamilton–Jacobi–Bellman equation ,Fuzzy control system ,Fuzzy logic ,Nonlinear system ,Computational Theory and Mathematics ,Artificial Intelligence ,Control and Systems Engineering ,Control theory ,Robust control ,Fuzzy risk - Abstract
This article investigates the adaptive fuzzy control problem for a class of stochastic nonlinear systems with the risk-sensitive performance index. The desired cost level of the risk-sensitive index, which could be arbitrarily small, is guaranteed by the solution of a specified Hamilton–Jacobi–Bellman (HJB) equation. By considering the unknown uncertainties of the stochastic nonlinear systems, a novel adaptive fuzzy risk-sensitive control method is proposed, which guarantees the input-to-state stability of the system. In addition, the proposed control strategy also reduces the conservatism of the existing adaptive robust control method. Finally, the effectiveness of the proposed approach is verified by a simulation example of one-link manipulator.
- Published
- 2021
26. Small-signal modeling and robust multi-loop PID and H∞ controllers synthesis for a self-excited induction generator
- Author
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Toufik Amieur, Metin Demirtas, Haris Calgan, and Moussa Sedraoui
- Subjects
0209 industrial biotechnology ,Operating point ,Computer science ,Applied Mathematics ,020208 electrical & electronic engineering ,Induction generator ,PID controller ,02 engineering and technology ,Computer Science Applications ,020901 industrial engineering & automation ,Control and Systems Engineering ,Control theory ,Voltage controller ,Robustness (computer science) ,0202 electrical engineering, electronic engineering, information engineering ,Sensitivity (control systems) ,Electrical and Electronic Engineering ,Robust control ,Instrumentation - Abstract
This paper presents modeling and designing of robust multi-loop controllers for the terminal voltage and stator frequency regulations of three-phase self-excited induction generator (SEIG) driven by a prime mover. The lack of the internal functionality of the SEIG system often represents a major challenge for most researchers. This is due to the several reasons, such as the absence of perfect mathematical models describing the actual behavior of SEIG, existence of some non-linear modes to be neglected during the linearization step and presence of unavoidable model uncertainties, etc. For this purpose, a small-signal-based method is proposed in order to overcome these drawbacks by designing the frequency and voltage linear models of the SEIG around its operating point. These models are carried out through the preprocessed experimental data recorded previously from actual SEIG system. Each appropriate model is independently computed using the identification toolbox of Matlab® software. The main advantage of the small-signal-based modeling is its simplicity without any knowledge of the equivalent circuit parameters of the SEIG. Accordingly, three robust voltage H ∞ controllers are synthesized from solving a weighted-mixed sensitivity problem using both classical and structured H ∞ synthesis. Each robust voltage controller and a robust frequency controller are operated with together as multi-loop controller. The novelty and contribution of the proposed method involve adjusting the parameters of the robust multi-loop controllers that ensure a good trade-off between performances and robustness using the small-signal model of the voltage and frequency in correspondence with the preselected operating point, recorded and pre-processed input–output data of the SEIG. The advantage of the multi-loop controllers is ensured not only for the nominal plant but also for all neighboring uncertainty models. The real-time implementation of controllers is performed using STM32 microcontroller unit. Simulation and experimental tests show the validity of the proposed linear small-signal models as well as the effectiveness of each proposed robust multi-loop controllers in terms of Nominal Performance (NP) margin, Robust Stability (RS) margin and the trade-off between them. However, when the operating point of the SEIG system changes significantly according to its nominal state, the guarantee of NP-RS trade-off becomes insecure.
- Published
- 2021
27. An off-line approach for output feedback robust model predictive control
- Author
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Andrey Polyakov, Tingyu Lin, Xubin Ping, Xiaojuan Wang, and Baocang Ding
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Output feedback ,Model predictive control ,Computer Networks and Communications ,Control and Systems Engineering ,Computer science ,Control theory ,Applied Mathematics ,Bounded function ,Signal Processing ,Table (database) ,Robust control ,Invariant (mathematics) ,Off line - Abstract
For constrained linear parameter varying systems subject to bounded disturbances and noises, this article investigates an off-line output feedback robust model predictive control approach. The sub-observer gains with robust positively invariant sets, and sub-controller gains with robust control invariant sets are simultaneously off-line optimized and stored in a look-up table. According to real-time estimation error bounds and estimated states, the time-varying sub-observer gains and sub-controller gains are on-line searched. The proposed off-line output feedback robust model predictive control approach with the guarantee of nested robust positively invariant sets and robust control invariant sets in theory reduces the on-line computational burden.
- Published
- 2021
28. Operational control based on environmental detector for floating LNG connection system during side-by-side offloading operation
- Author
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Yuxiang Zhang, Bernard Voon Ee How, Xiaoling Liang, and Shuzhi Sam Ge
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Computer science ,Applied Mathematics ,Mechanical Engineering ,Detector ,Feed forward ,Aerospace Engineering ,Ocean Engineering ,Sea state ,Control and Systems Engineering ,Control theory ,Dynamic positioning ,Floating liquefied natural gas ,Electrical and Electronic Engineering ,Robust control ,Liquefied natural gas - Abstract
This paper addresses the dynamic positioning problem for Liquefied Natural Gas (LNG) carrier with unknown shielding effect via a sea state detector and robust control design. First, to deal with the shielding effect existing between LNG facility and LNG carrier, sea state detector is developed to estimate the variation of wave force on the LNG carrier. In addition, the wind drag coefficients can be obtained adaptively to achieve feedforward control. Then, to guarantee a safe operation, a robust constrained control with prescribed performance is proposed considering actuator dynamic. Further, once a large wave force is identified in the detector, Neural Network compensator will be activated in the controller. Lyapunov analysis is conducted to ensure the boundedness of all the closed-loop states. Finally, the feasibility of the theoretical results is demonstrated by simulation studies.
- Published
- 2021
29. Robust stability and stabilization of fractional-order systems with polytopic uncertainties via homogeneous polynomial parameter-dependent matrix forms
- Author
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Jun-Guo Lu and Siyou Luo
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Fractional-order system ,Order (ring theory) ,Stability (probability) ,Computer Science Applications ,Theoretical Computer Science ,Matrix (mathematics) ,Control and Systems Engineering ,Modeling and Simulation ,Homogeneous polynomial ,Applied mathematics ,Robust control ,Matrix form ,Parameter dependent ,Information Systems ,Mathematics - Abstract
This paper addresses the robust stability and stabilization problems for fractional-order systems with polytopic uncertainties. By introducing homogeneous polynomial parameter-dependent matrix form...
- Published
- 2021
30. Robust gain-scheduling H∞ control of uncertain continuous-time systems having magnitude- and rate-bounded actuators: An application of full block S-procedure
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Hakan Yazici and Ibrahim Beklan Kucukdemiral
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Computer Networks and Communications ,Computer science ,Applied Mathematics ,Slew rate ,Acceleration ,Gain scheduling ,Control and Systems Engineering ,Control theory ,Bounded function ,Signal Processing ,Robust control ,Actuator ,Representation (mathematics) ,Block (data storage) - Abstract
This paper addresses a novel robust gain-scheduling(GS) state-feedback (SF) H ∞ (induced L 2 ) control method for uncertain continuous-time(CT) systems having actuators with hard rate and magnitude bounds. The proposed method relies on acceleration form representation of the uncertain CT system. The technique enables the user to represent the control signal and its slew rate as auxiliary outputs along with the main controlled output. Two different norms, namely the induced L ∞ and L 2 are used to control the system effectively. While the L ∞ gain from the exogenous disturbance inputs to the control signal related outputs is used to deal with actuator saturation problem, L 2 gain from the disturbance inputs to the performance outputs is utilised in attenuation of the effects of the disturbances. To achieve these goals with minimal conservatism, we develop new forms of dilated Matrix Inequality (MI) conditions for peak-to-peak gain and L 2 gain with no additional conservatism. Then, we propose a novel robust GS control methodology to deal with the problem via dilated MIs and a modified full block S-procedure method (MFBSPM). The utilisation of MFBSPM ensures that the robust control design method of this note applies to any uncertain system having rational parameter dependence. Finally, the efficiency of the presented method is portrayed through extensive simulations of the responses of a marine vessel to wave excitations in which the vessel model is assumed to have magnitude and rate limited active fin stabiliser.
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- 2021
31. Novel Optimal Adaptive Robust Control for Fuzzy Underactuated Mechanical Systems: A Nash Game Approach
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Hao Sun, Han Zhao, Xiaolong Chen, and Shengchao Zhen
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Nonholonomic system ,Dynamical systems theory ,Computer science ,Applied Mathematics ,Fuzzy set ,Optimal control ,Fuzzy logic ,symbols.namesake ,Computational Theory and Mathematics ,Artificial Intelligence ,Control and Systems Engineering ,Nash equilibrium ,Control theory ,symbols ,Robust control ,Game theory - Abstract
This article addresses the problems of the adaptive robust control design and the parameters optimization for a class of underactuated mechanical systems. We describe the uncertainty by using the fuzzy set theory to form the fuzzy dynamical systems. A novel adaptive robust control with two tunable gain parameters is designed based on the formed system, and the nonholonomic servo constraints are also considered in the control design. By employing the principle of the Nash game theory, we establish an optimization method for the two gain parameters, and the Nash equilibrium orients the optimal values of the two gain parameters. Finally, the effectiveness of the designed optimal control is shown by a numerical simulation.
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- 2021
32. Observer-based state feedback H∞ control for offshore steel jacket structures under denial-of-service attacks
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Zhihui Cai, Bao-Lin Zhang, Binrui Wang, Qing-Long Han, and En-Zhi Cao
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0209 industrial biotechnology ,Matching (graph theory) ,Observer (quantum physics) ,Computer science ,Applied Mathematics ,020208 electrical & electronic engineering ,Control (management) ,Denial-of-service attack ,02 engineering and technology ,Networked control system ,Computer Science Applications ,020901 industrial engineering & automation ,Control and Systems Engineering ,Control theory ,0202 electrical engineering, electronic engineering, information engineering ,State (computer science) ,Electrical and Electronic Engineering ,Robust control ,Instrumentation - Abstract
This article focuses on observer-based state feedback H ∞ control for a jacket structure against DoS attacks and external wave loads. First, a networked model of the structure is formulated as a switched delay system, in which DoS attacks and network-induced delays are considered simultaneously. A matching switched observer is developed for estimating states of the networked jacket structure system. Then, some new sufficient conditions are provided for the observer-based networked H ∞ controller for the resultant switched system. Finally, it is shown from several case studies that the provided mechanism can maintain desired performance of the jacket structure against attacks and wave loads. In addition, the developed control schemes can save the control cost significantly.
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- 2021
33. Robust mode transition control of four-wheel-drive hybrid electric vehicles based on radial basis function neural network estimation-a simulation study
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Fazhan Tao, Zhumu Fu, and Ling Li
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Jerk ,Computational Theory and Mathematics ,Computer science ,Control theory ,Applied Mathematics ,Control system ,Estimator ,Torque ,Clutch ,Electrical and Electronic Engineering ,Robust control ,Computer Science Applications ,Power (physics) - Abstract
Purpose The flexible mode transitions, multiple power sources and system uncertainty lead to challenges for mode transition control of four-wheel-drive hybrid powertrain. Therefore, the purpose of this paper is to improve dynamic performance and fuel economy in mode transition process for four-wheel-drive hybrid electric vehicles (HEVs), overcoming the influence of system uncertainty. Design/methodology/approach First, operation modes and transitions are analyzed and then dynamic models during mode transition process are established. Second, a robust mode transition controller based on radial basis function neural network (RBFNN) is proposed. RBFNN is designed as an uncertainty estimator to approximate lumped model uncertainty due to modeling error. Based on this estimator, a sliding mode controller (SMC) is proposed in clutch slipping phase to achieve clutch speed synchronization, despite disturbance of engine torque error, engine resistant torque and clutch torque. Finally, simulations are carried out on MATLAB/Cruise co-platform. Findings Compared with routine control and SMC, the proposed robust controller can achieve better performance in clutch slipping time, engine torque error, vehicle jerk and slipping work either in nominal system or perturbed system. Originality/value The mode transition control of four-wheel-drive HEVs is investigated, and a robust controller based on RBFNN estimation is proposed. Compared results show that the proposed controller can improve dynamic performance and fuel economy effectively in spite of the existence of uncertainty.
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- 2021
34. Energy shaping dynamic tube-MPC for underactuated mechanical systems
- Author
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Guaraci Bastos, Enrico Franco, Engineering & Physical Science Research Council (EPSRC), and Engineering & Physical Science Research Council (E
- Subjects
Technology ,STABILIZATION ,Computer science ,Passivity ,Robust control ,ROBUST ,Aerospace Engineering ,Ocean Engineering ,Mechanics ,IDA-PBC ,Stability (probability) ,09 Engineering ,ADAPTIVE-CONTROL ,Compensation (engineering) ,Engineering ,Control theory ,Port-Hamiltonian systems ,Electrical and Electronic Engineering ,OPTIMIZATION ,TIME ITERATION SCHEME ,01 Mathematical Sciences ,Interconnection ,Science & Technology ,Dynamic tube-MPC ,STABILITY ,Underactuation ,Applied Mathematics ,Mechanical Engineering ,Acoustics ,OPEN-LOOP ,INVARIANCE ,Engineering, Mechanical ,Underactuated systems ,Model predictive control ,Nonlinear system ,Control and Systems Engineering ,IMMERSION ,MODEL-PREDICTIVE CONTROL - Abstract
This work investigates the tracking control problem for underactuated mechanical systems. To this end, we develop an extension of the dynamic tube Model Predictive Control (MPC) approach by combining an MPC design, an ancillary energy shaping controller constructed with the Interconnection and Damping Assignment Passivity-Based Control methodology, and an analytical expression of the dynamic tube. In addition, we extend the proposed approach by including the adaptive compensation of a class of unknown disturbances. The stability analysis is presented by employing a Lyapunov approach. The effectiveness of the proposed controller is demonstrated with simulations on two underactuated systems: a two-mass-spring-damper system with uncertain damping and either linear or nonlinear spring; an inertia-wheel-pendulum with unmodeled disturbances.
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- 2021
35. A numerical investigation of Brockett’s ensemble optimal control problems
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Francesco Fanelli, Jan Bartsch, Souvik Roy, and Alfio Borzì
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msc:49K20 ,Scheme (programming language) ,Dynamical systems theory ,Applied Mathematics ,Numerical analysis ,MathematicsofComputing_NUMERICALANALYSIS ,msc:35L03 ,Optimal control ,Numerical methodology ,Computational Mathematics ,symbols.namesake ,Strang splitting ,Lagrange multiplier ,ComputingMethodologies_SYMBOLICANDALGEBRAICMANIPULATION ,symbols ,msc:49M15 ,Applied mathematics ,msc:65M08 ,ddc:510 ,Robust control ,computer ,Mathematics ,computer.programming_language - Abstract
This paper is devoted to the numerical analysis of non-smooth ensemble optimal control problems governed by the Liouville (continuity) equation that have been originally proposed by R.W. Brockett with the purpose of determining an efficient and robust control strategy for dynamical systems. A numerical methodology for solving these problems is presented that is based on a non-smooth Lagrange optimization framework where the optimal controls are characterized as solutions to the related optimality systems. For this purpose, approximation and solution schemes are developed and analysed. Specifically, for the approximation of the Liouville model and its optimization adjoint, a combination of a Kurganov–Tadmor method, a Runge–Kutta scheme, and a Strang splitting method are discussed. The resulting optimality system is solved by a projected semi-smooth Krylov–Newton method. Results of numerical experiments are presented that successfully validate the proposed framework.
- Published
- 2021
36. Periodic compensation of continuous‐time linear systems with norm‐bounded parametric uncertainties
- Author
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Ankit Deshmukh and Arun Ghosh
- Subjects
Computer science ,Mechanical Engineering ,General Chemical Engineering ,Linear system ,Biomedical Engineering ,Aerospace Engineering ,Industrial and Manufacturing Engineering ,Compensation (engineering) ,Control and Systems Engineering ,Norm (mathematics) ,Bounded function ,Applied mathematics ,Electrical and Electronic Engineering ,Robust control ,Parametric statistics - Published
- 2021
37. Deterministic Adaptive Robust Control With a Novel Optimal Gain Design Approach for a Fuzzy 2-DOF Lower Limb Exoskeleton Robot System
- Author
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Ye-Hwa Chen, Siyang Yang, Jiang Han, and Lian Xia
- Subjects
Computer science ,Estimation theory ,Applied Mathematics ,Fuzzy set ,Cooperative game theory ,Fuzzy logic ,Gait (human) ,Computational Theory and Mathematics ,Artificial Intelligence ,Control and Systems Engineering ,Control theory ,Uniform boundedness ,Robust control ,Game theory - Abstract
To enhance the lower limbs’ rehabilitation training of stroke patients, in this article, a deterministic adaptive robust control with control gain parameters optimized by a novel cooperative game theory is proposed for the two-degree-of-freedom (DOF) lower limb exoskeleton robot system (LLERs) with uncertainties and external disturbances. On the one hand, the deterministic adaptive robust control put forward will guarantee the uniform boundedness and uniform ultimate boundedness of gait constraint deviation and parameter estimation error. On the other hand, for uncertainties and external disturbance (possibly fast time-varying), which will arise in the two-DOF LLERs inevitably, we suppose that these uncertainties and disturbances are bounded, and their bounds are lying within the fuzzy sets, which can be characterized by membership functions; with such descriptions and control performance analysis, a novel cooperative game with two players participated will be formulated to seek the Pareto optimal solutions for the control gains of deterministic adaptive robust control proposed, and furthermore, the existence of optimal solutions is also shown by invoking a numerical technique. Eventually, the simulation results presented have verified the effectiveness of our proposed methodology on improving rehabilitation training of lower limbs.
- Published
- 2021
38. Nash game‐based adaptive robust control design optimization for the underactuated mechanical system with fuzzy evidence theory
- Author
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Chunsheng He, Yunjun Zheng, and Han Zhao
- Subjects
Optimal design ,Underactuated mechanical systems ,Control and Optimization ,Control and Systems Engineering ,Control theory ,Computer science ,Applied Mathematics ,Game based ,Robust control ,Fuzzy logic ,Software - Published
- 2021
39. Robust tracking error feedback control for output regulation of Euler–Bernoulli beam equation
- Author
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Tingting Meng and Bao-Zhu Guo
- Subjects
Control and Optimization ,Observer (quantum physics) ,Applied Mathematics ,Internal model ,Tracking (particle physics) ,Tracking error ,Compact space ,Operator (computer programming) ,Control and Systems Engineering ,Control theory ,Signal Processing ,Convergence (routing) ,Robust control ,Mathematics - Abstract
In this paper, we consider robust output tracking for an Euler–Bernoulli beam equation under the guidance of the internal model principle, where the disturbances in all possible channels are considered. Three typical cases are investigated in terms of different regulated outputs. The first case is based on boundary displacement output, for which only asymptotic convergence can be achieved due to the compactness of the observation operator. The second case considers two outputs of both boundary displacement and velocity. Since the control is one-dimensional, we can only arbitrarily regulate the boundary displacement and at the same time, the velocity is regulated to track the derivative of the reference. This is not the standard form investigated in the literature for robust error feedback control of abstract infinite-dimensional systems. The last case represents an extreme case that the system is non-well posed. In all the above cases, this paper demonstrates the same technique of an observer-based approach to robust control design. In the latter two cases, we can achieve exponential convergence and the closed loop is also shown to be robust to system uncertainties. Numerical simulations are carried out in all cases to illustrate the effectiveness of the proposed controls.
- Published
- 2021
40. Optimal design of adaptive robust control for a planar two-DOF redundantly actuated parallel robot
- Author
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Xiaomin Zhao, Fangfang Dong, Jiang Han, Shan Chen, and Peng Wang
- Subjects
Optimal design ,Computer science ,Applied Mathematics ,Mechanical Engineering ,Parallel manipulator ,Aerospace Engineering ,Ocean Engineering ,Optimal control ,Robot end effector ,law.invention ,Constraint (information theory) ,Control and Systems Engineering ,Control theory ,law ,Uniform boundedness ,Torque ,Electrical and Electronic Engineering ,Robust control - Abstract
An adaptive robust control combined with a multi-objective parameter optimization method for a parallel robot under unknown uncertainty is proposed. In the active joint space, the model of the parallel robot can be obtained by combining the closed-chain constraint force and the open-chain system’s dynamic equation. Based on the Udwadia–Kalaba theory, the closed-chain constraint force imposed by the end effector can be calculated if no uncertainty. If there is uncertainty, we propose an adaptive robust control, based on a set of feasible design parameters, which guarantees deterministic performances, including uniform boundedness and uniform ultimate boundedness. To seek the optimal choice of the design parameters, among the feasible pool. We examine the system performance, which includes the transient performance, the steady state performance, and the control cost. By a fuzzy-theoretic D-operation, a performance index is formulated. The problem of choosing the optimal control parameters is equivalent to the problem of finding the minimum value of the performance index. An illustrative example demonstrates the superiority of the adaptive robust control. Mass uncertainty and external disturbance torque are introduced to test the effectiveness of the proposed control strategy.
- Published
- 2021
41. Real time observer and control scheme for a wind turbine system based on a high order sliding modes
- Author
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Ali Karami-Mollaee, Oscar Barambones, Jose Maria Gonzalez de Durana, Patxi Alkorta, José Antonio Cortajarena, and Isidro Calvo
- Subjects
Lyapunov stability ,Maximum power principle ,Observer (quantum physics) ,Computer Networks and Communications ,Computer science ,020209 energy ,Applied Mathematics ,020208 electrical & electronic engineering ,02 engineering and technology ,Sliding mode control ,Turbine ,Wind speed ,Control and Systems Engineering ,Control theory ,Signal Processing ,0202 electrical engineering, electronic engineering, information engineering ,Robust control - Abstract
The introduction of advanced control algorithms may improve considerably the efficiency of wind turbine systems. This work proposes a high order sliding mode (HOSM) control scheme based on the super twisting algorithm for regulating the wind turbine speed in order to obtain the maximum power from the wind. A robust aerodynamic torque observer, also based on the super twisting algorithm, is included in the control scheme in order to avoid the use of wind speed sensors. The presented robust control scheme ensures good performance under system uncertainties avoiding the chattering problem, which may appear in traditional sliding mode control schemes. The stability analysis of the proposed HOSM observer is provided by means of the Lyapunov stability theory. Experimental results show that the proposed control scheme, based on HOSM controller and observer, provides good performance and that this scheme is robust with respect to system uncertainties and external disturbances.
- Published
- 2021
42. Analysis, Design of Control Algorithms and Applications for Forward Invariance of Hybrid Systems
- Author
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Chai, Jun
- Subjects
Robotics ,Engineering ,Applied mathematics ,Control Lyapunov Functions ,Control theory ,Feedback control ,Forward invariance ,Hybrid system ,Robust control - Abstract
This dissertation focuses on developing tools to study the robust forward invariance of sets for systems with unknown disturbances and hybrid dynamics. In particular, the notions of robust forward invariance properties are proposed for hybrid dynamical systems modeled by differential and difference inclusions with state-depending conditions enabling flows and jumps. A set is said to enjoy robust forward invariance for a system when its solutions start within the set always stay in the set regardless of disturbances. These proposed notions allow for a diverse type of solutions (with and without disturbances), including solutions that have persistent flow and jumps, that are Zeno, and that stop to exist after finite amount of (hybrid) time. Moreover, sufficient conditions for sets to enjoy such properties are presented. The proposed conditions involve the system data and the set to be rendered robust forward invariant.Furthermore, such conditions are exploited to derive conditions guaranteeing that sublevel sets of Lyapunov-like functions are robust forward invariant and, in turn, inspired a constructive way to design invariance-based control algorithms for a class of hybrid systems with control inputs and disturbances. More precisely, when a hybrid system have a Lyapunov-like function V satisfying a set of specific conditions, existence of feedback laws that render sublevel sets of V robustly forward invariant for the closed-loop hybrid systems are presented. In addition, two selection theorems are proposed to design invariance-based controllers for the class of hybrid systems considered.Applications and academic examples are given to illustrate the results. In particular, the presented forward invariance analysis and design tools are applied to the design and validate of hybrid controllers for power conversion systems, specifically, a single-phase DC/AC inverter and a DC/DC boost converter. Moreover, results are applied to the estimation of weakly forward invariant sets, which is an invariance property of interest when employing invariance principles to study convergence properties of solutions. Finally, the developed algorithms are tested on the control of a constrained bouncing ball system.
- Published
- 2018
43. Visual object tracking challenges revisited: VOT vs. OTB.
- Author
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Bei, Sun, Zhen, Zuo, Wusheng, Luo, Liebo, Du, and Qin, Lu
- Subjects
- *
OBJECT tracking (Computer vision) , *ROBUST control , *ARTIFICIAL intelligence , *MACHINE learning , *DATABASES - Abstract
Numerous benchmark datasets and evaluation toolkits have been designed to facilitate visual object tracking evaluation. However, it is not clear which evaluation protocols are preferred for different tracking objectives. Even worse, different evaluation protocols sometimes yield contradictory conclusions, further hampering reliable evaluation. Therefore, we 1) introduce the new concept of mirror tracking to measure the robustness of a tracker and identify its over-fitting scenarios; 2) measure the robustness of the evaluation ranks produced by different evaluation protocols; and 3) report a detailed analysis of milestone tracking challenges, indicating their application scenarios. Our experiments are based on two state-of-the-art challenges, namely, OTB and VOT, using the same trackers and datasets. Based on the experiments, we conclude that 1) the proposed mirror tracking metrics can identify the over-fitting scenarios of a tracker, 2) the ranks produced by OTB are more robust than those produced by VOT, and 3) the joint ranks produced by OTB and VOT can be used to measure failure recovery. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
44. Maximizing adaptive power in neuroevolution.
- Author
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Pagliuca, Paolo, Milano, Nicola, and Nolfi, Stefano
- Subjects
- *
NEUROSCIENCES , *BIOLOGICAL evolution , *PROBLEM solving , *ACQUISITION of data , *ROBUST control - Abstract
In this paper we compare systematically the most promising neuroevolutionary methods and two new original methods on the double-pole balancing problem with respect to: the ability to discover solutions that are robust to variations of the environment, the speed with which such solutions are found, and the ability to scale-up to more complex versions of the problem. The results indicate that the two original methods introduced in this paper and the Exponential Natural Evolutionary Strategy method largely outperform the other methods with respect to all considered criteria. The results collected in different experimental conditions also reveal the importance of regulating the selective pressure and the importance of exposing evolving agents to variable environmental conditions. The data collected and the results of the comparisons are used to identify the most effective methods and the most promising research directions. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
45. A robust gene regulatory network inference method base on Kalman filter and linear regression.
- Author
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Pirgazi, Jamshid and Khanteymoori, Ali Reza
- Subjects
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GENE regulatory networks , *KALMAN filtering , *REGRESSION analysis , *GENE expression , *ROBUST control - Abstract
The reconstruction of the topology of gene regulatory networks (GRNs) using high throughput genomic data such as microarray gene expression data is an important problem in systems biology. The main challenge in gene expression data is the high number of genes and low number of samples; also the data are often impregnated with noise. In this paper, in dealing with the noisy data, Kalman filter based method that has the ability to use prior knowledge on learning the network was used. In the proposed method namely (KFLR), in the first phase by using mutual information, the noisy regulations with low correlations were removed. The proposed method utilized a new closed form solution to compute the posterior probabilities of the edges from regulators to the target gene within a hybrid framework of Bayesian model averaging and linear regression methods. In order to show the efficiency, the proposed method was compared with several well know methods. The results of the evaluation indicate that the inference accuracy was improved by the proposed method which also demonstrated better regulatory relations with the noisy data. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
46. Free-living and laboratory gait characteristics in patients with multiple sclerosis.
- Author
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Storm, Fabio A., Nair, K. P. S., Clarke, Alison J., Van der Meulen, Jill M., and Mazzà, Claudia
- Subjects
- *
MULTIPLE sclerosis , *GAIT in humans , *COMPUTER algorithms , *TWO-way analysis of variance , *ROBUST control - Abstract
Background: Wearable sensors offer the potential to bring new knowledge to inform interventions in patients affected by multiple sclerosis (MS) by thoroughly quantifying gait characteristics and gait deficits from prolonged daily living measurements. The aim of this study was to characterise gait in both laboratory and daily life conditions for a group of patients with moderate to severe ambulatory impairment due to MS. To this purpose, algorithms to detect and characterise gait from wearable inertial sensors data were also validated. Methods: Fourteen patients with MS were divided into two groups according to their disability level (EDSS 6.5–6.0 and EDSS 5.5–5.0, respectively). They performed both intermittent and continuous walking bouts (WBs) in a gait laboratory wearing waist and shank mounted inertial sensors. An algorithm (W-CWT) to estimate gait events and temporal parameters (mean and variability values) using data recorded from the waist mounted sensor (Dynaport, Mc Roberts) was tested against a reference algorithm (S-REF) based on the shank-worn sensors (OPAL, APDM). Subsequently, the accuracy of another algorithm (W-PAM) to detect and classify WBs was also tested. The validated algorithms were then used to quantify gait characteristics during short (sWB, 5–50 steps), intermediate (iWB, 51–100 steps) and long (lWB, >100 steps) daily living WBs and laboratory walking. Group means were compared using a two-way ANOVA. Results: W-CWT compared to S-REF showed good gait event accuracy (0.05–0.10 s absolute error) and was not influenced by disability level. It slightly overestimated stride time in intermittent walking (0.012 s) and overestimated highly variability of temporal parameters in both intermittent (17.5%–58.2%) and continuous walking (11.2%–76.7%). The accuracy of W-PAM was speed-dependent and decreased with increasing disability. The ANOVA analysis showed that patients walked at a slower pace in daily living than in the laboratory. In daily living gait, all mean temporal parameters decreased as the WB duration increased. In the sWB, the patients with a lower disability score showed, on average, lower values of the temporal parameters. Variability decreased as the WB duration increased. Conclusions: This study validated a method to quantify walking in real life in people with MS and showed how gait characteristics estimated from short walking bouts during daily living may be the most informative to quantify level of disability and effects of interventions in patients moderately affected by MS. The study provides a robust approach for the quantification of recognised clinically relevant outcomes and an innovative perspective in the study of real life walking. [ABSTRACT FROM AUTHOR]
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- 2018
- Full Text
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47. Minimum energy multiple crack propagation. Part I: Theory and state of the art review.
- Author
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Sutula, Danas, Kerfriden, Pierre, van Dam, Tonie, and Bordas, Stéphane P.A.
- Subjects
- *
ROBUST control , *MICROELECTROMECHANICAL systems , *MATHEMATICAL models , *DYNAMICAL systems , *APPLIED mathematics - Abstract
The three-part paper deals with energy-minimal multiple crack propagation in a linear elastic solid under quasi-static conditions. The principle of minimum total energy, i.e. the sum of the potential and fracture energies, which stems directly from the Griffith’s theory of cracks, is applied to the problem of arbitrary crack growth in 2D. The proposed formulation enables minimisation of the total energy of the mechanical system with respect to the crack extension directions and crack extension lengths to solve for the evolution of the mechanical system over time. The three parts focus, in turn, on (I) the theory of multiple crack growth including competing cracks, (II) the discrete solution by the extended finite element method using the minimum-energy formulation, and (III) the aspects of computer implementation within the Matlab programming language. The key contributions of Part-I of this three-part paper are given as follows. (1) Formulation of the total energy functional governing multiple crack behaviour. (2) Three solution methods to the problem of competing crack growth for different fracture front stabilities, e.g. stable, unstable, or partially stable crack tip configurations; we compare our approach to Budyn et al. (2004) and demonstrate via example cases that the latter approach of resolving competing crack growth is not energy minimal in some cases. Finally, (3), the minimum energy criterion for a set of crack tip extensions is posed as the condition of vanishing rotational dissipation rates with respect to the extension angles. The proposed formulation lends itself to a straightforward application within a discrete framework involving multiple finite-length crack tip extensions. The open-source Matlab code, documentation, benchmark/example cases are included as supplementary material. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
48. An Adaptive Fuzzy H∞ Synergetic Approach to Robust Control.
- Author
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Medjbeur, L., Harmas, M. N., Benaggoune, S., and Zehar, K.
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APPLIED mathematics , *ELECTROMAGNETIC induction , *ENGINES , *MOTORS , *PERIODICALS - Abstract
Robust control often requires some adaptive approach in evaluating systems dynamics to handle parameters variations and external disturbances. Therefore, an error due to dynamics approximation is inevitably added to uncertainties already present in the model. This issue is addressed in this paper, through the combination of two robust techniques, Hinf and synergetic control. These latter are used to ensure reducing tracking error in the overall closed-loop system while guaranteeing stability via Lyapunov synthesis. With the aim of handling parameters variations, an indirect adaptive fuzzy scheme is used to elaborate system model. Simulation studies are conducted to assess the proposed approach on two practical systems, and the results are compared to a sliding mode proportional integral (PI)-based technique. It is to be noted that a large class of systems depicted as control affine systems will be considered in this paper. An induction motor and an inverted pendulum representing, respectively, a linear and a nonlinear system are utilized in this study showing improvement due to the suggested approach, in overall performance over its sliding mode control counterpart. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
49. Real-time robustness evaluation of regression based myoelectric control against arm position change and donning/doffing.
- Author
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Hwang, Han-Jeong, Hahne, Janne Mathias, and Müller, Klaus-Robert
- Subjects
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ELECTROMYOGRAPHY , *POSTURE , *COGNITIVE ability , *REAL-time control , *ROBUST control , *REGRESSION analysis - Abstract
There are some practical factors, such as arm position change and donning/doffing, which prevent robust myoelectric control. The objective of this study is to precisely characterize the impacts of the two representative factors on myoelectric controllability in practical control situations, thereby providing useful references that can be potentially used to find better solutions for clinically reliable myoelectric control. To this end, a real-time target acquisition task was performed by fourteen subjects including one individual with congenital upper-limb deficiency, where the impacts of arm position change, donning/doffing and a combination of both factors on control performance was systematically evaluated. The changes in online performance were examined with seven different performance metrics to comprehensively evaluate various aspects of myoelectric controllability. As a result, arm position change significantly affects offline prediction accuracy, but not online control performance due to real-time feedback, thereby showing no significant correlation between offline and online performance. Donning/doffing was still problematic in online control conditions. It was further observed that no benefit was attained when using a control model trained with multiple position data in terms of arm position change, and the degree of electrode shift caused by donning/doffing was not severely associated with the degree of performance loss under practical conditions (around 1 cm electrode shift). Since this study is the first to concurrently investigate the impacts of arm position change and donning/doffing in practical myoelectric control situations, all findings of this study provide new insights into robust myoelectric control with respect to arm position change and donning/doffing. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
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50. Adaptive robust control for active suspension systems: targeting nonholonomic reference trajectory and large mismatched uncertainty
- Author
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Feifei Liu, Shangbin Long, Wu Qin, and Pingzheng Ge
- Subjects
Nonholonomic system ,Computer science ,Underactuation ,Holonomic ,Applied Mathematics ,Mechanical Engineering ,Aerospace Engineering ,Ocean Engineering ,Active suspension ,Nonlinear system ,Control and Systems Engineering ,Control theory ,Sprung mass ,Uniform boundedness ,Electrical and Electronic Engineering ,Robust control - Abstract
We formulate control goals of nonlinear underactuated active suspension systems (ASSs) with uncertainties as a class of constraints, which may be holonomic or nonholonomic. The uncertainties in the sprung mass, the external disturbance, the control input, the spring force and damping force are (possibly fast) time-varying, unknown but bounded. However, the bounds are unknown. The task is to design control which drives systems to approximately obey the constraints (hence constraint-following control) under the uncertainties effect. Since these uncertainties do not all fall within the range space of the input matrix, we creatively decompose uncertainties into matched portion and mismatched portion that may be large. Consequently, this decomposition is able to ensure the mismatched portions of uncertainties to “disappear,” which indicates that the control design can be based on only matched portions. To emulate a constant design parameter vector that may be relevant to bounds of the uncertainties, we construct a continuous adaptive law, which call it smooth-zone adaptive law. This sets a base for an adaptive robust control design. We prove the uniform boundedness and the uniform ultimate boundedness of ASSs under the proposed control by the Lyapunov approach. Furthermore, experimental and numerical simulation results on a 2-DOF nonlinear ASS with uncertainties are presented for demonstrations of the proposed control.
- Published
- 2021
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