Spatial filtering of multi-channel signals is considered to be an effective pre-processing approach for improving signal-to-noise ratio. The use of spatial filtering for preprocessing high-density (HD) surface electromyogram (sEMG) helps to extract critical spatial information, but its application to non-invasive examination of neuromuscular changes have not been well investigated. Aimed at evaluating how spatial filtering can facilitate examination of muscle paralysis, three different spatial filtering methods are presented using principle component analysis (PCA) algorithm, non-negative matrix factorization (NMF) algorithm, and both combination, respectively. Their performance was evaluated in terms of diagnostic power, through HD-sEMG clustering index (CI) analysis of neuromuscular changes in paralyzed muscles following spinal cord injury (SCI). The experimental results showed that: (1) The CI analysis of conventional single-channel sEMG can reveal complex neuromuscular changes in paralyzed muscles following SCI, and its diagnostic power has been confirmed to be characterized by the variance of Z scores; (2) the diagnostic power was highly dependent on the location of sEMG recording channel. Directly averaging the CI diagnostic indicators over channels just reached a medium level of the diagnostic power; (3) the use of either PCA-based or NMF-based filtering method yielded a greater diagnostic power, and their combination could even enhance the diagnostic power significantly. This study not only presents an essential preprocessing approach for improving diagnostic power of HD-sEMG, but also helps to develop a standard sEMG preprocessing pipeline, thus promoting its widespread application.

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Spatial filtering for enhanced high-density surface electromyographic examination of neuromuscular changes and its application to spinal cord injury

Technology plays a vital role in patient rehabilitation, improving the quality of life of an individual. The increase in functional independence of disabled individuals requires adaptive and commercially available solutions. The use of sensor-based technology helps patients and therapeutic practices beyond traditional therapy. Adapting skeletal tracking technology could automate exercise tracking, records, and feedback for patient motivation and clinical treatment interventions and planning. In this paper, an exoskeleton was designed and subsequently developed for patients who are suffering from monoparesis in the upper extremities. The exoskeleton was developed according to the dimensions of a patient using a 3D scanner, and then fabricated with a 3D printer; the mechanism for the movement of the hand is a tendon flexion mechanism with servo motor actuators controlled by an ATMega2560 microcontroller. The exoskeleton was used for force augmentation of the patient’s hand by taking the input from the hand via flex sensors, and assisted the patient in closing, opening, grasping, and picking up objects, and it was also able to perform certain exercises for the rehabilitation of the patient. The exoskeleton is portable, reliable, durable, intuitive, and easy to install and use at any time.

Design of Portable Exoskeleton Forearm for Rehabilitation of Monoparesis Patients Using Tendon Flexion Sensing Mechanism for Health Care Applications

This paper addresses the whole angle approximations of aerodynamic coefficients. Several nonlinear approximations are proposed to describe lift, drag and side force coefficients in the range from 0 to 360 degrees based on accuracy and simplicity.

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Whole angle approximations of aerodynamic coefficients

Received: 22 February 2019 Accepted: 1 July 2019 In this study, we are interested in the asymptotic modeling of the two-dimensional stationary flow of a viscous incompressible fluid around wing airfoil. The aim of the present paper is to use the method of matched asymptotic expansions to study the laminar boundary layer behavior over a NACA (National Aeronautic and Space Administration) airfoil. At large Reynolds number and using singular perturbations methods, we distinguish the problems inside and outside the boundary layer. These problems are coupled under asymptotic constraints according to the least degeneration principle. Using the affinity hypothesis for the velocity field in the boundary layer, and assuming that the transverse velocity is of order ꓳ(Re-1/2), we establish an approached composite solution, and follows the aerodynamic coefficients (drag and lift) are determined. The results obtained show that accurate modeling is possible for laminar incompressible flow. The predicted solutions obtained compare well with the results of a NACA43013 airfoil produced by the Ansys fluent.

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Asymptotic Modeling the Aerodynamic Coefficients of The NACA Airfoil

Three methods for approximating aerodynamic coefficients at high AOAs (incl. flat plate) (4,5) were verified against the 360°wind tunnel measurements of the DU96-W-180 airfoil (6,7). The best method (4) was chosen and modified in order to produce a satisfactory approximation of airfoil aerodynamic coefficients in the whole AOA range with the lowest possible number of data points necessary to tune the model. Further, a method for the approximation of Cm similar to (4) was found. Additionally, a range of AOAs in the vicinity of 180°was found at which the aerodynamic coefficients may be obtained with computationally inexpensive steady 2D CFD. This was done by a comparison of the results obtained with 2D steady CFD (8,9,10) with the results obtained with unsteady 3D CFD (8,9,10). Note that obtaining the aerodynamic characteristics in the AOA range approximately between -30°and 30°is easy as this data may be computed with 2D CFD or is typically available from wind tunnel measurements. Therefore, this AOA range is outside the scope of the present work. On the other hand, accurate prediction of airfoil aerodynamic characteristics at high AOAs by means of CFD or wind tunnel measurements proves difficult. CFD computations capable of resolving the physics of flows at high AOAs are 3D and computationally expensive. This increases the need for an engineering model capable of delivering reliable airfoil characteristics at high AOAs by using a relatively low number of reference data points obtained by 3D CFD or cautious wind tunnel measurements.

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Parametric approximation of airfoil aerodynamic coefficients at high angles of attack

Harmonic Representation of Aerodynamic Lift and Drag Coefficients

Performances of Coriolis vibratory gyroscopes can be improved not only by proper sensitive element design, but by subsequent signal processing as well. Noises and disturbances can be either completely filtered out or reduced by means of static or dynamic filtering and well-modelled errors can be compensated using both modulated and demodulated signal processing and control. In this chapter, we study different algorithms of signal processing aimed at the improvement of CVG performances.

Vladislav Apostolyuk

Papers

Harmonic Representation of Aerodynamic Lift and Drag Coefficients

Signal Processing and Control