In this paper, we present a methodology for classifying normal, atrial fibrillation (AF), non-AF related other abnormal heart rhythms and noisy recordings by analysing single lead ECG signal of short duration. In a two layer binary cascaded approach proposed in our methodology, an unlabelled recording is initially classified into one of the two intermediate classes ('normal+others' and 'AF+noisy') at the first layer before actual classification at the second layer. The Physionet Challenge 2017 dataset containing more than 8500 ECG recordings are used for creation of training models and interval validation. The proposed methodology yields an average F1-score of 0.91, 0.79 and 0.77 respectively in classifying normal, AF and other rhythms on the training dataset using 5-fold cross validation. Results also show that, the said methodology, when applied on a hidden test set maintained by the challenge organisers yields F1-score values of 0.92, 0.86 and 0.74 in classifying the same. IntroductionAtrial Fibrillation (AF) is a common type of heart disease that leads to stroke, heart failure or other complications. Millions of people get affected by AF every year and the prevalence of the disease is likely to increase. Noninvasive detection of AF is a popular area of research for quite a long time. Irregularities in heart beat is considered to be the most common symptom of AF and can be traced in an ECG. However, being an episodic event an accurate detection of AF is not always trivial. Conventional AF detectors ([1], [2], [3]) are mostly of atrial activity analysisbased or ventricular response analysis-based methods. The absence of P waves or the presence of f waves in the TQ interval are searched in atrial activity analysis-based AF detectors. On the other hand, time, frequency and morphological features are extracted from RR intervals to identity the heart beat irregularity in ventricular response analysisbased methods.However, the prior art methods have certain limitations regarding real time deployments. 1) Most of them are validated on clinically accepted 12 lead ECG signals, recorded for a relatively longer duration. 2) Algorithms are mostly applied on carefully selected clean data. However, in practical scenario, ECG signals are often noisy in nature. 3) Size of the test dataset are often not adequate for making a conclusion. 4) Most prior arts perform binary classification between AF and normal recordings only. However, there are many non-AF abnormal rhythms (like tachycardia, bradycardia, arrhythmia etc) which exhibits heart beat pattern similar to AF. Considering them in the in the dataset makes the classification task more challenging. In this paper we propose a robust algorithm for classifying normal, AF, other abnormal rhythms and noisy ECG recordings. The diverse ECG dataset, provided in Physionet challenge 2017 [4] is used for internal performance evaluation and creating the training models. Information regarding individual recordings are not available regarding the other rhythms in the dataset as...

Impedance control is an efficient and stable method of providing trajectory and force control in robotic systems. The procedure by which the impedance of the manipulator is changed is a very important aspect in the design of impedance based control schemes. In this work, a scheme is presented in which the control of impedance at the interface of the end effector and the space structure is achieved by introduction of a passive degree of freedom (DOF) in the controller of the robotic system. The impedance is shown to depend upon a compensation gain for the dynamics of the passive DOF. To illustrate the methodology, an example of a two DOF planer space robot is considered.

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In this paper, the extended Lagrangian formulation for a one-dimensional continuous system with gyroscopic coupling and non-conservative fields has been developed. Using this formulation, the dynamics of an internally and externally damped rotor driven through a dissipative coupling has been studied. The invariance of the extended or so-called umbraLagrangian density is obtained through an extension of Noether's theorem. The rotor shaft is modeled as a Rayleigh beam. The dynamic behavior of the rotor shaft is obtained and validated through simulation studies. Results show an interesting phenomenon of limiting behavior of the rotor shaft with internal damping beyond certain threshold speeds which are obtained theoretically and affirmed by simulations. It is further observed that there is entrainment of whirling speeds at natural frequencies of the rotor shaft primarily depending on the damping ratio.