A prominent change is being carried out in the fields of rehabilitation and assistive exoskeletons in order to actively aid or restore legged locomotion for individuals suffering from muscular impairments, muscle weak...
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ISBN:
(纸本)9781424492695
A prominent change is being carried out in the fields of rehabilitation and assistive exoskeletons in order to actively aid or restore legged locomotion for individuals suffering from muscular impairments, muscle weakness, neurologic injury, or disabilities that affect the lower limbs. This paper presents a characterization of knee motion patterns from Surface Electromyography (sEMG) signals, measured in the Erector spinae (ES) muscle. Feature extraction (mean absolute value, waveform length and auto-regressive model) and pattern classification methods (Linear Discrimination Analysis, K-Nearest Neighborhood and Support Vector Machine) are applied for recognition of eight-movement classes. Additionally, several channels setup are analyzed to obtain a suitable electrodes array. The results were evaluated based on signals measured from lower limb using quantitative metric such as error rate, sensitivity, specificity and predictive positive value. A high accuracy (> 95%) was obtained, which suggest that it is possible to detect the knee motion intention from ES muscle, as well as to reduce the electrode number (from 2 to 3 channels) to obtain an optimal electrodes array. This implementation can be applied for myoelectric control of lower limb active exoskeletons.
In this paper the resonant behavior of frequency selective surfaces, FSS, using matryoshka geometry is analyzed considering polarizations x and y. The basics of the FSS using matryoshka geometry are described for usua...
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This paper discusses the fault tolerance performance of two hybrid six-phase drive systems under single-phase open-circuit fault. The topologies are considered to be hybrid because each of the two three-phase groups o...
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This paper presents the evaluation of seven techniques of feature extraction (PSD, F-Test, EMD, MCE, CCA, LASSO and MSI) for gaze-target detections in a SSVEP-based BCI. Two type of technologies for visual stimulation...
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This paper presents the evaluation of seven techniques of feature extraction (PSD, F-Test, EMD, MCE, CCA, LASSO and MSI) for gaze-target detections in a SSVEP-based BCI. Two type of technologies for visual stimulation were used (LCD and LEDs). Five differents windows lengths (1, 2, 4, 5 and 10 s) were used and seven volunteers participated in this study. The highest accuracy obtained in all cases was 93.57% using LEDs and the highest ITR was 36.90 bits/min for LCD. The technique based on MSI shows the highest success rate in both cases (LCD or LED) and is even more noticeable when the window size is increased.
This paper presents the comparation of three different feature extraction techniques based on the Empirical Mode Decomposition (EMD) for a SSVEP-BCI. This approach based on the characterization of the signal by EMD, i...
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ISBN:
(纸本)9781479924004
This paper presents the comparation of three different feature extraction techniques based on the Empirical Mode Decomposition (EMD) for a SSVEP-BCI. This approach based on the characterization of the signal by EMD, is proposed as a novel alternative to other techniques and it was demonstrated that it exceeds both in accuracy rate and Information Transfer Rate (ITR). The experiments were performed in an offline way, and seven volunteers participated of the study. The stimulis were generated both by LCD and LEDs. The frequencies used were 8, 11, 13 and 15 Hz. The results here reported such represent the average of the seven participants, achieving a success rate of 81% and ITR of 23.32 bits/min of the total set of cases analyzed. It is further confirmed that the highest success rates and ITRs were obtained for stimulation by LEDs.
This paper presents a three-phase integrated PFC AC-AC resonant inverter with boost effect for Induction Heating (IH) Application. This converter is composed by three independent half-bridge boost rectifier and class ...
ISBN:
(数字)9781728148298
ISBN:
(纸本)9781728148304
This paper presents a three-phase integrated PFC AC-AC resonant inverter with boost effect for Induction Heating (IH) Application. This converter is composed by three independent half-bridge boost rectifier and class D resonant inverters with non-smoothed DC link that achieve high power factor operation. The magnetic coupling of the three coils was measured for characterizing the resonant behavior of the arrangement. Experimental results validate the modes of operation with ZVS and the converter performance in the entire power input range (PF and THD).
In this work it is proposed a multilevel T-type configuration for a high-frequency pulsating DC-link inverter for three-phase applications. The configuration consists of two DC/DC-pulsating converters cascaded with a ...
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In this work it is proposed a multilevel T-type configuration for a high-frequency pulsating DC-link inverter for three-phase applications. The configuration consists of two DC/DC-pulsating converters cascaded with a DC-link capacitor-less three-phase three-level T-type inverter. Due to the absence of DC-link electrolytic capacitors, the proposed inverter guarantees a long lifetime and high power density. The DC-DC-pulsating converters aim to generate the high-frequency pulsating DC-link waveform profiles which have to be synchronized with the three-phase inverter PWM. Comparing to the conventional PWM, the proposed technique presents reduced switching losses due to the fact only one leg commutes during a switching period while the other two legs keep clamped in high or low impedance. Details of control strategy and modulation are presented, such as experimental results to validate the theoretical approach.
This paper proposes a 4.3 kW three-phase integrated PFC AC-AC resonant inverter for Induction Heating (IH) Application. This converter is composed by three independent resonant inverters with non-smoothed DC link that...
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This paper proposes a 4.3 kW three-phase integrated PFC AC-AC resonant inverter for Induction Heating (IH) Application. This converter is composed by three independent resonant inverters with non-smoothed DC link that achieves high power factor operation. The magnetic coupling of the three coils was modeled by using the impedance matrix for characterizing the resonant behavior of the arrangement. The coils arrangement with weak coupling between coils is applied for induction water heater. Experimental results validate the modes of operation with ZVS and the converter performance in the entire power input range (PF and THD).
In this paper, a Four-Port AC/DC-DC/AC conversion system is proposed using two full-bridge converters and a high-frequency transformer following the principle of Dual Active Bridge Converter. Two full-bridge AC/DC sin...
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In this paper, a Four-Port AC/DC-DC/AC conversion system is proposed using two full-bridge converters and a high-frequency transformer following the principle of Dual Active Bridge Converter. Two full-bridge AC/DC single-phase converters are connected by coupling their boost inductance to create a high-frequency transformer of the resulting proposed converter. The isolated power transfer between converters is controlled by the duty cycles and the phase-shift applied to the primary and secondary of the split transformer. The boundaries of the switching modes and the power transferred through the high-frequency transformer were obtained analytically. The system feasibility was validated by simulations and by a 300 W prototype with 94.9% maximum efficiency.
An active orthosis (AO) is a robotic device that assists both human gait and rehabilitation therapy. This work proposes portable AOs, one for the knee joint and another for the ankle joint. Both AOs will be used to ...
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An active orthosis (AO) is a robotic device that assists both human gait and rehabilitation therapy. This work proposes portable AOs, one for the knee joint and another for the ankle joint. Both AOs will be used to complete a robotic system that improves gait rehabilitation. The requirements for actuator selection, the biomechanical considerations during the AO design, the finite element method, and a control approach based on electroencepha-lographic and surface electromyographic signals are reviewed. This work contributes to the design of AOs for users with foot drop and knee flexion impairment. However, the potential of the proposed AOs to be part of a robotic gait rehabilitation system that improves the quality of life of stroke survivors requires further investigation.
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