155 research outputs found
Construyendo alternativas satisfactorias al discurso público estigmatizante en enfermos mentales con esquizofrenia
Adaptive Compensation Strategy For The Tracking/Rejection of Signals with Time-Varying Frequency in Digital Repetitive Control Systems
Digital repetitive control is a technique which al-
lows to track periodic references and/or reject peri-
odic disturbances. Repetitive controllers are usually de-
signed assuming a fixed frequency for the signals to be
tracked/rejected, its main drawback being a dramatic per-
formance decay when this frequency varies. A usual ap-
proach to overcome the problem consists of an adap-
tive change of the sampling time according to the refer-
ence/disturbance period variation. However, this sam-
pling period adaptation implies parametric changes af-
fecting the closed-loop system behavior, that may compro-
mise the system stability. This article presents a design
strategy which allows to compensate for the parametric
changes caused by sampling period adjustment. Stabil-
ity of the digital repetitive controller working under time-
varying sampling period is analyzed. Theoretical devel-
opments are illustrated with experimental results.Peer ReviewedPostprint (published version
Non-uniform sampling in digital repetitive control systems: An LMI stability analysis
Digital repetitive control is a technique which allows to track periodic references and/or reject periodic disturbances. Repetitive controllers are usually designed assuming a fixed frequency for the signals to be tracked/rejected, its main drawback being a dramatic performance decay when this frequency varies. A usual approach to overcome the problem consists of an adaptive change of the sampling time according to the reference/disturbance period variation. This report presents a stability analysis of a digital repetitive controller working under time-varying sampling period by means of an LMI gridding approach. Theoretical developments are illustrated with experimental results
Design and Analysis Strategies for Digital Repetitive Control Systems with Time-Varying Reference/Disturbance Period
This article introduces and analyzes the performance
features of different design schemes for digital repetitive
control systems subject to references/disturbances that exhibit
non-uniform frequency. Aiming for the maintenance of a
constant value for the ratio Tp/Ts, where Tp is the period of
the reference/disturbance signal and Ts is the sampling period,
two approaches are proposed. The first one deals with the realtime
adaptation of Ts to the actual changes of Tp; the stability
issue is studied by means of an LMI gridding method and also
using robust control techniques. The second one propounds the
introduction of an additional compensator that annihilates the
effect of the time-varying sampling in the closed-loop system
and forces its behavior to coincide with the one corresponding
to an a priori selected nominal sampling period; the procedure
needs the internal stability of the compensator-plant subsystem,
which is checked by means of LMI gridding. The theoretical
results are experimentally tested and compared through a
mechatronic plant model.Postprint (published version
Lifting velocity predicts the maximum number of repetitions to failure with comparable accuracy during the Smith machine and free-weight prone bench pull exercises
This study compared the accuracy of the fastest mean velocity from set (MVfastest) to predict the
maximum number of repetitions to failure (RTF) between 2 variants of prone bench pull (PBP)
exercise (Smith machine and free-weight) and 3 methods (generalized, individualized multiplepoint,
and individualized 2-point). Twenty-three resistance-trained males randomly performed
2 sessions during Smith machine PBP and 2 sessions during free-weight PBP in different weeks.
The first weekly session determined the RTF-MVfastest relationships and subjects completed single
sets of repetitions to failure against 60-70-80-90%1RM. The second weekly session explored the
accuracy of RTFs prediction under fatigue conditions and subjects completed 2 sets of 65%1RM
and 2 sets of 85%1RM with 2 min of rest. The MVfastest associated with RTFs from 1 to 15 were
greater for Smith machine compared to free-weight PBP (F ≥ 42.9; P < 0.001) and for multiplepoint
compared to 2-point method (F ≥ 4.6; P ≤ 0.043). The errors when predicting RTFs did not
differ between methods and PBP variants, whereas all RTF-MVfastest relationships overestimated
the RTF under fatigue conditions. These results suggest that RTF–MVfastest relationships present
similar accuracy during Smith machine and free-weight PBP exercises and it should be constructed
under similar training conditions.The Biomedicine Doctoral Studies of the University of Granada, SpainSpanish Ministry of University
under a predoctoral grant (FPU19/01137)Spanish Ministry of Science and Innovation [PID2019-
110074GBI00/SRA/10.13039/501100011033)
An educational approach to the internal model principle for periodic signals
This article presents an educational approach to resonant control and repet-
itive control, which are Internal Model Principle-based control techniques speci cally de-
signed for the tracking/rejection of periodic signals. The analytical formulation is com-
pleted by a set of simulations and physical experiments on a mechatronic educational
plant integrated in a virtual/remote laboratory. The laboratory features are oriented to
realize the limited performance of classic PID control to reject non-constant disturbances
and, at the same time, to show the effectiveness of the Internal Model Principle for the
rejection of periodic disturbances by means of resonators and repetitive control. Assess-
ment based on students' perception reveals it as a useful distance learning tool. The
laboratory is integrated in Automatl@bs, a Spanish interuniversity network of web-based
laboratories devoted to distance learning of control engineering.Postprint (published version
Odd-harmonic repetitive control of an active filter under varying network frequency: control design and stability analysis
This work deals with the design and analysis of a
controller for a shunt active power filter. The design is based
on combined feedforward and feedback actions, the last using
repetitive control, and aims at the obtention of a good closedloop
performance in spite of the possible frequency variations
that may occur in the electrical network. As these changes
affect the performance of the controller, the proposal includes
a compensation technique consisting of an adaptive change of
the digital controller’s sampling time according to the network
frequency variation. However, this implies structural changes in
the closed-loop system that may destabilize the overall system.
Hence, this article is also concerned with closed-loop stability of
the resulting system, which is analyzed using a robust control
approach through the small gain theorem. Experimental results
that indicate good performance of the closed-loop system are
provided.Postprint (published version
Maximal and submaximal intended velocity squat sets: Do they selectively impact mechanical performance in paired multijoint upper‐body exercise sets?
This study aimed to investigate how squat protocols performed at maximal and
submaximal intended velocities during interset periods of paired upper‐body exercises
that impact the mechanical performance of these multijoint upper‐body
exercises. Twenty‐one young and healthy adults (seven women) completed three
experimental sessions, each comprising four sets of five repetitions at 75% of their
1‐repetition maximum, with a 4‐min break between sets using the bench press and
bench pull exercises. The experimental sessions differed in the protocol utilized
during the interset periods: (i) Passive—no physical exercise was performed; (ii)
SQfast—5 repetitions of the squat exercise at maximal intended velocity against the
load associated with a mean velocity (MV) of 0.75 m s−1; and (iii) SQslow—5 repetitions
of the squat exercise at submaximal velocity (intended MV of 0.50 m s−1)
against the load associated with an MV of 0.75 m s−1. Level of significance was
p ≤ 0.05. The main findings revealed negligible differences (effect size [ES] < 0.20)
among the exercise protocols (passive vs. SQfast vs. SQslow) for all mechanical variables
during the bench pull, whereas during the bench press, small differences (ES
from 0.23 to 0.31) emerged favoring the passive protocol over SQfast and SQslow in
terms of mean set velocity and fastest MV of the set. The absence of significant
differences between the SQfast and SQslow protocols, irrespective of the particular
upper‐body exercise, implies that the intended lifting velocity does not influence the
potential interference effect during paired set training procedures.National Natural Science Foundation
of China under grant 12250410237Funding for open
access charge: Universidad de Granada/CBU
Intraocular pressure responses to a virtual reality shooting simulation in active-duty members of the Spanish Army: The influence of task complexity
Ocular physiology is sensitive to cognitively demanding tasks. However, it is unknown whether the intraocular
pressure is also affected by the cognitive demands of military operations. The main objective was to determine
the impact of a virtual reality shooting simulation with two levels of complexity on intraocular pressure levels in
military personnel. Eighteen active-duty members of the Spanish Army and eighteen civilians performed two 4
min simulated shooting tasks with two levels of complexity using a virtual reality. In the “easy” task participants
performed a simulated shoot when the stimulus (military with a rifle) appeared, while in the “difficult” task the
stimulus randomly was a military with a rifle or with his hands on the air and participants were instructed to
respond only when the military with a rifle appeared. Intraocular pressure was measured with a rebound
tonometer before and immediately after each task. Complementarily, perceived levels of mental load and
shooting performance (reaction time) were assessed. Intraocular pressure was greater after completing the more
complex task in both military personnel (p-value < 0.01, Cohen´s d = 1.19) and civilians (p-value < 0.01, Cohen´s
d = 1.16). Also, perceived levels of task load and reaction time were higher in the difficult compared to the easy
shooting tasks (both p < 0.001). The rise in intraocular pressure is positively associated with the cognitive
demands of simulated military operations. The potential application of this finding is the development of
objective tools based on intraocular pressure for the evaluation of the mental state in real-world contexts,
permitting to improve soldiers´safety and performance.CEMIX (Centro Mixto UGR-MADOC, Army of Spain) 5/4/20 TR-COMBAT
Revisión de control repetitivo digital en condiciones de frecuencia variable
El control repetitivo digital es una técnica que permite el seguimiento y rechazo de señales periódicas. Los controladores repetitivos son diseñados asumiendo que las señales a seguir/rechazar tienen una frecuencia fija y conocida, siendo su principal desventaja la degradación de desempeño cuando esta frecuencia varía. Este artículo presenta una revisión de las diferentes estrategias utilizadas con el fin de solventar dicha problemática.Digital repetitive control is a strategy that allows tracking/rejecting periodic signals. Repetitive controllers are designed assuming that the exogenous signal period is constant and known, its main drawback being the dramatic loss of performance when signal frequency varies. This paper reviews the most relevant proposals advanced for overcoming this problem
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