Closed loop cable robot for large horizontal workspaces

Sergio Juárez-Pérez,Antonio González-Rodriguez,Guillermo Rubio-Gómez,David Rodríguez-Rosa,Erika Ottaviano,Fernando J. Castillo-Garcia 국제구조공학회 2021 Smart Structures and Systems, An International Jou Vol.27 No.2

Inspection and maintenance of civil structures are important issues for sustainability of existing and new infrastructures. Classical approach relies on large human activities eventually performed in unsafe conditions. This paper proposed a non-invasive solution for inspecting horizontal surface such as decks of bridges. The proposal presented here is based in cable-driven robots and allows to inspect large surfaces maintaining a very low vertical occupancy in comparison to the conventional architecture of this kind of robot. Using closed cables loop instead of a set of cables a device with low motorization power and very large workspace is designed and prototyped. As example of control an inverse dynamics technique is applied to control the end-effector where inspection tool is located, e.g., a vision system. Experimental results demonstrate that this novel device allows to inspect large horizontal surfaces, with low motorization and low vertical occupancy.

Variable Gains Sliding Mode Control

Sergio Alvarez-Rodríguez,Gerardo Flores,Noé Alcalá Ochoa 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.3

In this paper a sliding mode control with variable gains is proposed. Such a controller has chatteringeffect reduction without detriment to the robustness properties of the sliding modes. The key idea behind the control design is that the variable gains magnitude is proportional to the trajectory tracking error magnitude. Also, this design establishes a connection between both the first and the second order sliding modes control. It is demonstrated that the proposed controller does not overestimates disturbances, which significantly reduces the control energy used. Finally, a stability analysis in the sense of Lyapunov is developed to demonstrate finite time convergence to the origin; simulations experiments are carried out to show the effectiveness and robustness of the proposed controller.

Competition/antagonism associations of biofilm formation among Staphylococcus epidermidis Agr groups I, II, and III

Sergio Martínez-García,César I. Ortiz-García,Marisa Cruz-Aguilar,Juan Carlos Zenteno,José Martin Murrieta-Coxca,Sonia Mayra Pérez-Tapia,Sandra Rodríguez-Martínez,Mario E. Cancino-Diaz,Juan C. Cancino- 한국미생물학회 2019 The journal of microbiology Vol.57 No.2

Staphylococci have quorum-sensing (QS) systems that enable cell-to-cell communication, as well as the regulation of numerous colonization and virulence factors. The accessory gene regulator (Agr) operon is one of the Staphylococcus genus QS systems. Three groups (I, II, and III) are present in Staphylococcus epidermidis Agr operon. To date, it is unknown whether Agr groups can interact symbiotically during biofilm development. This study analyzed a symbiotic association among Agr groups during biofilm formation in clinical and commensal isolates. Different combinations among Agr group isolates was used to study biofilm formation in vitro and in vivo (using a mouse catheter-infection model). The analysis of Agr groups were also performed from samples of human skin (head, armpits, and nostrils). Different predominant coexistence was found within biofilms, suggesting symbiosis type. In vitro, Agr I had a competition with Agr II and Agr III. Agr II had a competition with Agr III, and Agr II was an antagonist to Agr I and III when the three strains were combined. In vivo, Agr II had a competition to Agr I, but Agr I and II were antagonists to Agr III. The associations found in vitro and in vivo were also found in different sites of the skin. Besides, other associations were observed: Agr III antagonized Agr I and II, and Agr III competed with Agr I and Agr II. These results suggest that, in S. epidermidis, a symbiotic association of competition and antagonism occurs among different Agr groups during biofilm formation.

PID Principles to Obtain Adaptive Variable Gains for a Bi-order Sliding Mode Control

Sergio Alvarez-Rodríguez,Gerardo Flores 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.10

A new model to obtain adaptive variable gains for a bi-order Sliding Mode Control is proposed in this work. The variable gains for the controller are designed to dynamically adapt their values, using principles of the well-known Proportional-Integral-Derivative control technique, where the magnitude of the tracking error is the signal feedback. According to the way to tune parameters, it can become a first-order or a second-order controller. This design takes into account the actuators’ constraints (operational limits of the plant to control). As a result of theadaptive properties of the proposed scheme, the new controller significantly reduces the energy consumption in control processes, and it rejects the so-called chattering-effect, simultaneously maintaining the main robust properties of the Sliding Mode strategy. In order to show the feasibility and effectiveness of the proposed design, simulation results are presented, where the performance of the proposed controller is compared with the conventional Sliding Modes of order one and two, and also with the classical PID controller. A strong stability analysis in the sense of Lyapunov is presented, showing global exponential stability for the equilibrium point of the closed-loop control system when the proposed control design is used.

Wind-gust Compensation Algorithm based on High-gain Residual Observer to Control a Quadrotor Aircraft: Real-time Verification Task at Fixed Point

Abraham Efraim Rodríguez-Mata,Ivan González-Hernández,Jesus Gabriel Rangel-Peraza,Sergio Salazar,Rogelio Lozano Leal 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.2

Wind is considered a strong disturbance for quadrotor aircrafts (UAV) when an outdoor task at a fixed point is carried out. The effect of wind produces a distortion on the attitude of the vehicle which is reflected on undesired longitudinal movements. This paper addresses a real-time implementation and design of a robust embedded control-observer based on a type high-gain observer algorithm for on-line estimation and compensation of external disturbances produced by wind gusts on an autonomous quadrotor aircraft. A real-time experimental implementation of embedded Residual High Gain algorithm control is proposed in order to eliminate the effects of real perturbations in the hover position of the UAV. A Lyapunov function was used to practical stability analysis the system. Also numerical simulations were carried out to estimate wind behavior by the use of Drydel mathematical wind model. The main contribution of this work is the implementation of a Residual High Gain Observer in an outdoor real-time experiment in presence of real wind gusts perturbations. The proposed embedded algorithm control improves the stabilization of an UAV in the presence of real wind gusts with average of 8 m/s. The proposed algorithm improved the UAV behavior as shown by the GPS position experimental results, decreasing the wind effect on the translational movement of the aircraft.

Broadband, site selective and time resolved photoluminescence spectroscopic studies of finely size-modulated Y2O3:Eu3þ phosphors synthesized by a complex based precursor solution method

Sudeshna Ray,Sergio Fabián León-Luis,Francisco Javier Manjón,Miguel Alfonso Mollar,Óscar Gomis,Ulises Ruymán Rodríguez-Mendoza,Said Agouram,Alfonso Muñoz,Victor Lavín 한국물리학회 2014 Current Applied Physics Vol.14 No.1

Undoped and Eu3þ-doped cubic yttria (Y2O3) nanophosphors of good crystallinity, with selective particle sizes ranging between 6 and 37 nm and showing narrow size distributions, have been synthesized by a complex-based precursor solution method. The systematic size tuning has been evidenced by transmission electron microscopy, X-ray diffraction, and Raman scattering measurements. Furthermore, sizemodulated properties of Eu3þ ions have been correlated with the local structure of Eu3þ ion in different sized Y2O3:Eu3þ nanophosphors by means of steady-state and time-resolved site-selective laser spectroscopies. Time-resolved site-selective excitation measurements performed in the 7F0 / 5D0 peaks of the Eu3þ ions at C2 sites have allowed us to conclude that Eu3þ ions close to the nanocrystal surface experience a larger crystal field than those in the nanocrystal core. Under the site-selective excitation in the 7F0 / 5D0 peaks, energy transfer between the sites has also been observed.

Addition of passive-carriage for increasing workspace of cable robots: automated inspection of surfaces of civil infrastructures

Guillermo Rubio-Gómez,Sergio Juárez,David Rodríguez-Rosa,Enrique Bravo,Erika Ottaviano,Antonio Gonzalez-Rodriguez,Fernando J. Castillo-Garcia 국제구조공학회 2021 Smart Structures and Systems, An International Jou Vol.27 No.2

Cable-driven robots are parallel manipulators in which rigid links are replaced by actuated cables. The end-effector is then supported by a set of cables commanded by motors that are usually placed in a fixed frame. By varying the cables length, it is possible to change the end-effector position and/or orientation. Among the advantages presented by cable robots are they light-weight structure, high energy efficiency and their ability to cover large workspaces since cables are easy to wind. When high-speed operation is not required, a safer solution is to design cable-driven suspended robots, where all vertical components of cables tension are against gravity direction. Cable-driven suspended robots present limited workspace due to the elevated torque requirements for the higher part of the workspace. In this paper, the addition of a passive carriage in the top of the frame is proposed, allowing to achieve a much greater feasible workspace than the conventional one, i.e., with the same size as the desired inspection area while maintaining the same motor requirements. In the opposite, this new scheme presents non-desired vibration during the end-effector maneuvers. These vibrations can be removed by means of a more complex control strategy. Kinematics and dynamics models are developed in this paper. An analysis of sensor system is carried out and a control scheme is proposed for controlling the end-effector pose. Simulation and experimental results show that the feasible workspace can be notoriously increased while end-effector pose is controlled. This new architecture of cable-driven robot can be easily applied for automated inspection and monitoring of very large vertical surfaces of civil infrastructures, such as facades or dams.

Effects of nonlinear friction compensation in the inertia wheel pendulum

Carlos Aguilar-Avelar,Ricardo Rodríguez-Calderón,Sergio Puga-Guzmán,Javier Moreno-Valenzuela 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.9

This paper discusses for the first time the effects of modeling, identifying and compensating nonlinear friction for the control of the inertia wheel pendulum and proposes a new algorithm for the stabilization of the pendulum at the upward unstable position. First, it is shown that the dynamic model with the proposed asymmetric Coulomb friction component characterizes better the real experimental platform of the system. Then, a feedback linearization based controller with friction compensation was designed, where theoretical results show the stability of the output trajectories. Finally, the new algorithm was experimentally compared with its version without friction compensation, showing that the new scheme yields better performance with less power consumption.

Effectiveness of Thrombectomy in Stroke According to Baseline Prognostic Factors: Inverse Probability of Treatment Weighting Analysis of a Population- Based Registry

Salvatore Rudilosso,José Ríos,Alejandro Rodríguez,Meritxell Gomis,Víctor Vera,Manuel Gómez-Choco,Arturo Renú,Núria Matos,Laura Llull,Francisco Purroy,Sergio Amaro,Mikel Terceño,Víctor Obach,Joaquim Se 대한뇌졸중학회 2021 Journal of stroke Vol.23 No.3

Background and Purpose In real-world practice, the benefit of mechanical thrombectomy (MT) is uncertain in stroke patients with very favorable or poor prognostic profiles at baseline. We studied the effectiveness of MT versus medical treatment stratifying by different baseline prognostic factors. Methods Retrospective analysis of 2,588 patients with an ischemic stroke due to large vessel occlusion nested in the population-based registry of stroke code activations in Catalonia from January 2017 to June 2019. The effect of MT on good functional outcome (modified Rankin Score ≤2) and survival at 3 months was studied using inverse probability of treatment weighting (IPTW) analysis in three pre-defined baseline prognostic groups: poor (if pre-stroke disability, age >85 years, National Institutes of Health Stroke Scale [NIHSS] >25, time from onset >6 hours, Alberta Stroke Program Early CT Score <6, proximal vertebrobasilar occlusion, supratherapeutic international normalized ratio >3), good (if NIHSS <6 or distal occlusion, in the absence of poor prognostic factors), or reference (not meeting other groups’ criteria). Results Patients receiving MT (n=1,996, 77%) were younger, had less pre-stroke disability, and received systemic thrombolysis less frequently. These differences were balanced after the IPTW stratified by prognosis. MT was associated with good functional outcome in the reference (odds ratio [OR], 2.9; 95% confidence interval [CI], 2.0 to 4.4), and especially in the poor baseline prognostic stratum (OR, 3.9; 95% CI, 2.6 to 5.9), but not in the good prognostic stratum. MT was associated with survival only in the poor prognostic stratum (OR, 2.6; 95% CI, 2.0 to 3.3). Conclusions Despite their worse overall outcomes, the impact of thrombectomy over medical management was more substantial in patients with poorer baseline prognostic factors than patients with good prognostic factors.

Systemic Inflammatory Load in Young and Old Ringdoves Is Modulated by Consumption of a Jerte Valley Cherry-Based Product

Jonathan Delgado,María del Pilar Terrón,María Garrido,Carmen Barriga,Sergio Damián Paredes,Javier Espino,Beatriz Rodríguez 한국식품영양과학회 2012 Journal of medicinal food Vol.15 No.8

A chronic subclinical inflammatory status that coexists with immune dysfunction is commonly found in the elderly population. Consumption of foods rich in antioxidants (e.g., cherries) is an attractive strategy to reduce risk from chronic diseases. Based on previous studies showing the antioxidant effect of a Jerte Valley cherry derivative product in humans, the objective of this work was to evaluate the effect of the intake of a Jerte Valley cherry-based beverage on inflammatory load in both young and old ringdoves (Streptopelia risoria). To this purpose, circulating levels of proinflammatory and anti-inflammatory cytokines as well as serum levels of different acute-phase proteins were measured before and after a 10-day treatment with the Jerte Valley cherry-based beverage. Thus, the 10-day treatment with the cherry-based beverage modulated the balance of pro- and anti-inflammatory cytokines in both young and old ringdoves by down-regulating the levels of pro-inflammatory cytokines (interleukin [IL]-1b, tumor necrosis factor-a, and interferon-c) and up-regulating the levels of anti-inflammatory cytokines (IL-4, IL-2, and IL-10). Moreover, the 10-day treatment with the Jerte Valley cherrybased product reduced the levels of several proteins involved in acute-phase responses, such as C-reactive protein, haptoglobin,a2-macroglobulin, and serum amyloid P component. On the other hand, old birds showed imbalanced levels of inflammatory markers toward a pro-inflammatory status, thereby underlining the fact that aging is usually accompanied by systemic inflammation and inflammation-related chronic diseases. To sum up, the data suggest a potential health benefit by consuming the cherry-based beverage, especially in aged populations, through their anti-inflammatory properties.