A simplified version of adaptive super‐twisting control Gutierrez, Susana V.; De León‐Morales, Jesús; Plestan, Franck ...
International journal of robust and nonlinear control,
10 November 2019, Letnik:
29, Številka:
16
Journal Article
Recenzirano
Summary
In this paper, a simplified super‐twisting control with adaptive gain is proposed for a class of nonlinear uncertain systems. A strong Lyapunov function is constructed to design a sliding ...mode controller with adaptive gain. Furthermore, the analysis of the finite time convergence towards the equilibrium point of the closed‐loop system is detailed. Regarding previous works from literature, the main contribution of this approach is the simplification of the gain tuning process by maintaining a high level of performance. Finally, simulation results for tracking control of a quadrotor are given to show the performance of the proposed algorithm.
A novel kind of adaptive second order sliding mode control algorithm, based on super-twisting control law (STW), is proposed and applied to a floating wind turbine (FWT). This new algorithm, for ...which the controller gains are dynamically adjusted with respect to the uncertainties and perturbations, has a very reduced number of tuning parameters versus previous adaptive versions of STW, and low-requirement computational requirement. This new controller is particularly well-adapted to the FWT control problems because the achievement of an accurate modeling of such system is a hard task; furthermore, it strongly reduces the tuning effort with respect to previous adaptive versions of STW. The proposed algorithm is implemented on a FAST nonlinear FWT model in the SIMULINK environment, and the performances are compared with the standard gain scheduling PI (GSPI) control and the original adaptive STW. The results show high performances of the proposed controller for rotor speed regulation and reduction of platform pitch motion.
This paper addresses the design of attitude and airspeed controllers for a fixed wing unmanned aerial vehicle. An adaptive second order sliding mode control is proposed for improving performance ...under different operating conditions and is robust in presence of external disturbances. Moreover, this control does not require the knowledge of disturbance bounds and avoids overestimation of the control gains. Furthermore, in order to implement this controller, an extended observer is designed to estimate unmeasurable states as well as external disturbances. Additionally, sufficient conditions are given to guarantee the closed-loop stability of the observer based control. Finally, using a full 6 degree of freedom model, simulation results are obtained where the performance of the proposed method is compared against active disturbance rejection based on sliding mode control.
•An observer based control for tracking desired trajectories for a fixed wing unmanned aerial vehicle is proposed.•This approach is robust under parametric uncertainties and external disturbances via an extended state observer.•Extended observers are used to estimate the state vector and external perturbations.•The adaptive second order sliding mode controller ensures finite time convergence and requires less control effort.•Stability analysis for the observer based control is given.
Multilevel power converters belong to a class of hybrid systems, where continuous and discrete variables coexist, representing a challenge for their control design. Flying capacitor multilevel ...converters require controlling the flying capacitor voltages and the output current. In this regard, several works have studied this problem. However, the discrete nature of the converter has not been directly included in the control design. In this paper, a hybrid representation of the converter is considered, and using Petri net (PN) methodology, a control scheme is proposed to regulate the flying capacitor voltages and the output current. An analysis of stability, using Lyapunov method, is presented, and sufficient stability conditions are obtained. From these conditions, the commutation rules are defined and used to define the transition rules for the PNs. Experimental results validate the performance of the proposed scheme.
A mixture of blue corn, black bean, and chard with a moisture content (MC) of 22.3–35.7% is extruded at different extrusion temperatures (ET) (102—142 °C) using screw speeds (SP) of 96–172 rpm, and ...the extruded mixtures are subsequently expanded using microwave radiation to produce third‐generation (3G) snacks. The degree of starch gelatinization (DG); in vitro starch digestibility (SD); specific mechanical energy (SME); physical properties: radial expansion (RE), flexural modulus (Ef), and bulk density (BD); and rheological properties: storage modulus (G′) and loss modulus (G″) are evaluated and optimized. In addition, X‐ray and microstructure analyses are studied to correlate the chemical and structural changes. The SP and MC affect most variables in the unexpanded snack (UETS) and microwave‐expanded snacks (MWES). Increased MC results in UETS with low SD, DG, rheological properties, and mechanical resistance. An increase in SP at low MC results in MWES with high RE, low BD, and Ef while an increase in MC lowers SD. Micrographs and X‐ray diffraction spectra reveals that the extrusion results in a V‐type starch crystalline structure. The optimal conditions (24% MC, 133 rpm, and 122 °C) result in good expansion and moderate SD, DG, and SME products.
The present study mainly investigates the effect of extrusion processing on the properties rheological, structural, thermo‐mechanical, and in vitro starch digestibility of extruded and microwave‐expanded in a matrix based on blue corn, black beans, and chard third‐generation snack.
The aim of this study was to identify the
Colletotrichum
species associated with anthracnose symptoms in coffee (
Coffea arabica
L.) plantations in northern Puebla, Mexico. In 2013, five surveys were ...conducted in different production areas and at different altitudes. Symptomatic leaves, shoots, and ripe and unripe fruits of the coffee variety Red Caturra were collected. Isolates were obtained and the
Colletotrichum
species were identified morphologically and characterized by multilocus sequence analyses of the
ACT, CAL, GAPDH,
and
TUB2
genes and the rDNA region. Additionally, pathogenicity tests were conducted using six isolates. We identified
C. gigasporum, C. gloeosporioides, C. karstii
(two isolates)
, C. siamense
, and
C. theobromicola
. This is the first report of these five species infecting leaves of coffee. The symptoms caused by these species were characterized, but the species causing Coffee Berry Disease was not found. This is the first report of a complex of species affecting coffee plants in the same geographical area in Mexico, and suggests that other complexes of species may be important pathogens in coffee-producing areas elsewhere.
Mobile application to analyse surgical experience Garcia-Estrada, Everardo; Morales-Gómez, Jesús A; Delgado-Brito, Miriam ...
Neurocirugia (Asturias, Spain),
2020 Mar - Apr, 20200301, Letnik:
31, Številka:
2
Journal Article
Recenzirano
To quantify the surgical experience acquired by residents in the neurosurgery specialisation programme over a 6-month period.
A total of 13 residents enrolled in the neurosurgery specialisation ...programme from February 2018 to July 2018. Over this period, the procedures residents were involved in and the role they played were documented in the Electronic Neurosurgical Register. Residents who withdrew from the specialisation program were excluded.
A total of 530 procedures were performed during the study period. Observational learning and supervised practice are conducted primarily in the first and fifth years of residence, during which residents begin their training in emergency and elective surgeries, respectively. Residents are then able to independently perform emergency surgeries during the second and third years, and elective surgeries in the sixth year. Residents are able to instruct less experienced surgeons in the fourth year.
The Electronic Neurosurgical Register is an innovative technological tool that supports the fields of care, teaching and research. It records the exact number of patients who have undergone surgery at a particular time, providing valuable information for the proper management of resources. The data obtained can be used to identify areas of opportunity in the training of residents, facilitating the development of continuous improvement strategies in the training of competent neurosurgeons.
A differential drive catamaran unmanned surface vehicle tracking control in presence of external disturbances and uncertainties is addressed. A super-twisting control considering a single adaptive ...gain is adopted, where the number of tuning parameters of this control gain is reduced compared with standard adaptive super-twisting approaches. Furthermore, the gain exhibits smooth dynamics compared with controls using discontinuous functions signals. An analysis of the closed loop stability is provided using a Lyapunov approach. The proposed adaptive super-twisting approach is designed to drive the vessel along time-varying trajectories in presence of perturbations, ensuring robustness, and practical finite-time convergence. Numerical simulations, and real-time experimental tests using a prototype, illustrate the control performance under payload uncertainty and external perturbations. For further demonstration, a comparison with some of the existing versions of the super-twisting control included one with variable gain is provided.
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