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Douglas Antonio Plaza Guingla

Bio: Douglas Antonio Plaza Guingla is an academic researcher from Escuela Superior Politecnica del Litoral. The author has contributed to research in topics: Control theory & Robust control. The author has an hindex of 5, co-authored 8 publications receiving 77 citations.

Papers
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Journal ArticleDOI
TL;DR: An interval robust controller, by linear programming based on Kharitonov rectangle, is proposed to regulate the output of source converter, which shows the effectiveness of the proposed controller when the multi-converter buck–buck system is subjected to a variation of power reference.
Abstract: Multi-converter electronic systems are becoming widely used in many industrial applications; therefore, the stability of the whole system is a big concern to the real-world power supplies applications. A multi-converter system comprised of cascaded converters has a basic configuration that consists of two or more converters in series connection, where the first is a source converter that maintains a regulated dc voltage on the intermediate bus while remaining are load converters that convert the intermediate bus voltage to the tightly regulated outputs for the next system stage or load. Instability in cascaded systems may occur due to the constant power load (CPL), which is a behavior of the tightly regulated converters. CPLs exhibit incremental negative resistance behavior causing a high risk of instability in interconnected converters. In addition, there are other problems apart from the CPL, e.g., non-linearities due to the inductive element and uncertainties due to the imprecision of a mathematical model of dc-dc converters. Aiming to effectively mitigate oscillations effects in the output of source converter loaded with a CPL, in this paper, an interval robust controller, by linear programming based on Kharitonov rectangle, is proposed to regulate the output of source converter. Several tests were developed by using an experimental plant and simulation models when the multi-converter buck-buck system is subjected to a variation of power reference. Both simulation and experimental results show the effectiveness of the proposed controller. Furthermore, the performance indices computed from the experimental data show that the proposed controller outperforms a classical control technique.

37 citations

Journal ArticleDOI
TL;DR: A novel robust controller is presented, based on linear programming based on the Chebyshev theorem as a robust control technique considering the Kharitonov's theorem that ensures the minimization of the total deviation from the desired performance in a closed-loop system, specified by a family of characteristic polynomials.
Abstract: In recent years, dc microgrid (MG) is increasing rapidly in electric power grids and other isolated systems, integrating more efficiency and suite better some of the renewable energy sources, storage units, and dc loads. However, dc MG stability analysis becomes a challenge when constant power loads (CPLs) are applied to dc bus, which introduces destabilizing effects in the system due to its negative impedance characteristics. This paper presents a novel robust controller, based on linear programming based on the Chebyshev theorem as a robust control technique considering the Kharitonov’s theorem that ensures the minimization of the total deviation from the desired performance in a closed-loop system, specified by a family of characteristic polynomials. The purpose of the proposed controller is to tightly regulate the dc bus voltage, ensuring MG stability due to the effects of power variation on CPLs. The simulation and experimental tests are performed by using a MATLAB/Simulink simulator and a developed prototype of the DC MG system, respectively, to ratify the robustness and effectiveness of the proposed method of robust controller design.

34 citations

Proceedings ArticleDOI
01 May 2017
TL;DR: This paper aims to estimate the best picking place for a two suction cups vacuum gripper, when planar objects with an unknown size and geometry are considered, in such a way that minimizes the vacuum force needed to guarantee a grasp.
Abstract: In general, robot grasping approaches are based on the usage of multi-finger grippers. However, when large size objects need to be manipulated vacuum grippers are preferred, instead of finger based grippers. This paper aims to estimate the best picking place for a two suction cups vacuum gripper, when planar objects with an unknown size and geometry are considered. The approach is based on the estimation of geometric properties of object's shape from a partial cloud of points (a single 3D view), in such a way that combine with considerations of a theoretical model to generate an optimal contact point that minimizes the vacuum force needed to guarantee a grasp. Experimental results in real scenarios are presented to show the validity of the proposed approach.

21 citations

Proceedings ArticleDOI
01 Oct 2018
TL;DR: The results show that the optimized interval robust controller is able to maintain acceptable performance across the operating range, with a minor performance degradation compared to an intervals robust controller and a conventional controller.
Abstract: This paper presents the design and evaluation of an optimized interval controller of a buck converter. Uncertainties represent changes in the operating conditions of the system, resulting in degradation of performance of a conventional controller. To address this problem, an optimal robust controller is investigated, aiming to maintain acceptable dynamic performance throughout the range of permissible operating points. In order to maintain efficiency of control process at high level, the controller parameters are optimized by using the Chebyshev’s theorem as robust control technique that guarantees the minimization of the total deviation from the desired performance in a closed-loop system, specified by a family of characteristic polynomials. Simulation has been carried out using Matlab/Simulink. The results show that the optimized interval robust controller is able to maintain acceptable performance across the operating range, with a minor performance degradation compared to an interval robust controller and a conventional controller.

9 citations

Journal ArticleDOI
TL;DR: The proposed robust Fractional Order Proportional-Integral autotuning control strategy is presented and applied to heterogeneous dynamic systems using decentralized control and its performance is compared against two other fractional order controllers based on PI gain-crossover autotuned method and Internal Model Control.

6 citations


Cited by
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Proceedings ArticleDOI
21 May 2018
TL;DR: A compliant suction contact model is proposed that computes the quality of the seal between the suction cup and local target surface and a measure of the ability of thesuction grasp to resist an external gravity wrench.
Abstract: Vacuum-based end effectors are widely used in industry and are often preferred over parallel-jaw and multifinger grippers due to their ability to lift objects with a single point of contact. Suction grasp planners often target planar surfaces on point clouds near the estimated centroid of an object. In this paper, we propose a compliant suction contact model that computes the quality of the seal between the suction cup and local target surface and a measure of the ability of the suction grasp to resist an external gravity wrench. To characterize grasps, we estimate robustness to perturbations in end-effector and object pose, material properties, and external wrenches. We analyze grasps across 1,500 3D object models to generate Dex-Net 3.0, a dataset of 2.8 million point clouds, suction grasps, and grasp robustness labels. We use Dex-Net 3.0 to train a Grasp Quality Convolutional Neural Network (GQ-CNN) to classify robust suction targets in point clouds containing a single object. We evaluate the resulting system in 350 physical trials on an ABB YuMi fitted with a pneumatic suction gripper. When evaluated on novel objects that we categorize as Basic (prismatic or cylindrical), Typical (more complex geometry), and Adversarial (with few available suction-grasp points) Dex-Net 3.0 achieves success rates of 98%, 82%, and 58% respectively, improving to 81% in the latter case when the training set includes only adversarial objects. Code, datasets, and supplemental material can be found at http://berkeleyautomation.github.io/dex-net.

239 citations

Journal ArticleDOI
TL;DR: Various control approaches have been reviewed to match the impedance, such as the nonlinear disturbance observer (NDO) feedforward compensation method, linear programming algorithm, hybrid potential theory and linear system analysis of polyhedral uncertainty.
Abstract: In order to overcome the problem of power generation in distributed energy, microgrid(MG) emerges as an alternative scheme. Compared with the ac microgrids, the dc microgrids have the advantages of high system efficiency, good power quality, low cost, and simple control. However, due to the complexity of the distributed generation system, the conventional droop control shows the drawbacks of low current sharing accuracy. Therefore, the improved primary control methods to enhance current sharing accuracy are systematically reviewed, such as particle swarm optimization programming, probabilistic algorithm and voltage correction factor scheme. However, it is difficult to achieve stable and coordinated operation of the dc microgrids by relying on the primary control. Hence, the various secondary control approaches, such as dynamic current sharing scheme, muti-agent system (MAS) control and virtual voltage control methods have been summarized for voltage regulation. Furthermore, the energy management system (EMS), modular-based energy router (MBER) and other coordinated control methods are reviewed to achieve power management. Besides, various control methods to compensate the effect of communication delay are summarized. Moreover, linear matrix inequality (LMI), Lyapunov-Krasovskii functional stability and Takagi-Sugeno model prediction scheme can be adopted to eliminate the influence of communication delay. In addition, due to the constant power loads (CPL) exhibit negative impedance characteristics, which may result in the output oscillation of filter. Thus, various control approaches have been reviewed to match the impedance, such as the nonlinear disturbance observer (NDO) feedforward compensation method, linear programming algorithm, hybrid potential theory and linear system analysis of polyhedral uncertainty. The merits and drawbacks of those control strategies are compared in this paper. Finally, the future research trends of hierarchical control and stability in dc microgrids and dc microgrid clusters are also presented.

122 citations

Posted Content
TL;DR: In this article, a compliant suction contact model is proposed to compute the quality of the seal between the suction cup and local target surface and a measure of the ability of a suction grasp to resist an external gravity wrench.
Abstract: Vacuum-based end effectors are widely used in industry and are often preferred over parallel-jaw and multifinger grippers due to their ability to lift objects with a single point of contact. Suction grasp planners often target planar surfaces on point clouds near the estimated centroid of an object. In this paper, we propose a compliant suction contact model that computes the quality of the seal between the suction cup and local target surface and a measure of the ability of the suction grasp to resist an external gravity wrench. To characterize grasps, we estimate robustness to perturbations in end-effector and object pose, material properties, and external wrenches. We analyze grasps across 1,500 3D object models to generate Dex-Net 3.0, a dataset of 2.8 million point clouds, suction grasps, and grasp robustness labels. We use Dex-Net 3.0 to train a Grasp Quality Convolutional Neural Network (GQ-CNN) to classify robust suction targets in point clouds containing a single object. We evaluate the resulting system in 350 physical trials on an ABB YuMi fitted with a pneumatic suction gripper. When evaluated on novel objects that we categorize as Basic (prismatic or cylindrical), Typical (more complex geometry), and Adversarial (with few available suction-grasp points) Dex-Net 3.0 achieves success rates of 98$\%$, 82$\%$, and 58$\%$ respectively, improving to 81$\%$ in the latter case when the training set includes only adversarial objects. Code, datasets, and supplemental material can be found at this http URL .

111 citations

Journal ArticleDOI
TL;DR: An interval robust controller, by linear programming based on Kharitonov rectangle, is proposed to regulate the output of source converter, which shows the effectiveness of the proposed controller when the multi-converter buck–buck system is subjected to a variation of power reference.
Abstract: Multi-converter electronic systems are becoming widely used in many industrial applications; therefore, the stability of the whole system is a big concern to the real-world power supplies applications. A multi-converter system comprised of cascaded converters has a basic configuration that consists of two or more converters in series connection, where the first is a source converter that maintains a regulated dc voltage on the intermediate bus while remaining are load converters that convert the intermediate bus voltage to the tightly regulated outputs for the next system stage or load. Instability in cascaded systems may occur due to the constant power load (CPL), which is a behavior of the tightly regulated converters. CPLs exhibit incremental negative resistance behavior causing a high risk of instability in interconnected converters. In addition, there are other problems apart from the CPL, e.g., non-linearities due to the inductive element and uncertainties due to the imprecision of a mathematical model of dc-dc converters. Aiming to effectively mitigate oscillations effects in the output of source converter loaded with a CPL, in this paper, an interval robust controller, by linear programming based on Kharitonov rectangle, is proposed to regulate the output of source converter. Several tests were developed by using an experimental plant and simulation models when the multi-converter buck-buck system is subjected to a variation of power reference. Both simulation and experimental results show the effectiveness of the proposed controller. Furthermore, the performance indices computed from the experimental data show that the proposed controller outperforms a classical control technique.

37 citations

Journal ArticleDOI
TL;DR: A novel robust controller is presented, based on linear programming based on the Chebyshev theorem as a robust control technique considering the Kharitonov's theorem that ensures the minimization of the total deviation from the desired performance in a closed-loop system, specified by a family of characteristic polynomials.
Abstract: In recent years, dc microgrid (MG) is increasing rapidly in electric power grids and other isolated systems, integrating more efficiency and suite better some of the renewable energy sources, storage units, and dc loads. However, dc MG stability analysis becomes a challenge when constant power loads (CPLs) are applied to dc bus, which introduces destabilizing effects in the system due to its negative impedance characteristics. This paper presents a novel robust controller, based on linear programming based on the Chebyshev theorem as a robust control technique considering the Kharitonov’s theorem that ensures the minimization of the total deviation from the desired performance in a closed-loop system, specified by a family of characteristic polynomials. The purpose of the proposed controller is to tightly regulate the dc bus voltage, ensuring MG stability due to the effects of power variation on CPLs. The simulation and experimental tests are performed by using a MATLAB/Simulink simulator and a developed prototype of the DC MG system, respectively, to ratify the robustness and effectiveness of the proposed method of robust controller design.

34 citations