Online Frequency Estimation on a Building-like Structure Using a Nonlinear Flexible Dynamic Vibration Absorber

Human Gait Activity Recognition Using Multimodal Sensors

Human activity recognition is an application of machine learning with the aim of identifying activities from the gathered activity raw data acquired by different sensors. In medicine, human gait is commonly analyzed by doctors to detect abnormalities and determine possible treatments for the patient. Monitoring the patient's activity is paramount in evaluating the treatment's evolution. This type of classification is still not enough precise, which may lead to unfavorable reactions and responses. A novel methodology that reduces the complexity of extracting features from multimodal sensors is proposed to improve human activity classification based on accelerometer data. A sliding window technique is used to demarcate the first dominant spectral amplitude, decreasing dimensionality and improving feature extraction. In this work, we compared several state-of-art machine learning classifiers evaluated on the HuGaDB dataset and validated on our dataset. Several configurations to reduce features and training time were analyzed using multimodal sensors: all-axis spectrum, single-axis spectrum, and sensor reduction.

Boundary Controller Design for a Class of Horizontal Belt Transmission System with Boundary Vibration Constraint

In this paper, the problem of transverse vibration suppression of a belt system moving in the horizontal direction is investigated. This system is characterized by the boundary vibration constraint and is affected by external disturbances. For it, we introduced a logarithmic function in the candidate term of the Lyapunov function and used a symbolic function in the controller to compensate for the effects of boundary vibration constraints and boundary disturbances, respectively. In order to better achieve the control objective, we designed a boundary control scheme. The state feedback boundary controller was designed using the boundary signals of the system when they can be available directly. Considering the presence of noise in the practical system, some system signals cannot be measured accurately. Therefore, a high-gain observer was introduced to estimate these signals, and an output feedback boundary controller was designed. Finally, the simulation example showed that both controllers guarantee effective suppression of the transverse vibration of the system without violating the boundary vibration constraints.