A Fast Adaptive-Gain Orientation Filter of Inertial/magnetic Data for Human Motion Tracking in Free-Living Environments.

A fast Adaptive-Gain Orientation Filter of inertial/magnetic data for human motion tracking in free-living environments.

Filed under: Rehab Centers

Conf Proc IEEE Eng Med Biol Soc. 2012 Aug; 2012: 6760-3
Tian Y, Tan J

High-resolution, real-time data obtained by human motion tracking systems can be used for gait analysis, which helps better understanding the cause of many diseases for more effective treatments, such as rehabilitation for outpatients or recovery from lost motor functions after a stroke. This paper presents an analytically derived method for an adaptive-gain complementary filter based on the convergence rate from the Gauss-Newton optimization algorithm (GNA) and the divergence rate from the gyroscope, which is referred as Adaptive-Gain Orientation Filter (AGOF) in this paper. The AGOF has the advantages of one iteration calculation to reduce the computing load and accurate estimation of gyroscope measurement error. Moreover, for handling magnetic distortions especially in indoor environments and movements with excessive acceleration, adaptive measurement vectors and a reference vector for Earth’s magnetic field selection schemes are introduced to help the GNA find more accurate direction of gyroscope error. Experimental results are presented to verify the performance of the proposed method, which shows better accuracy of orientation estimation than several well-known methods.
HubMed – rehab

 

Robots and therapeutic play: Evaluation of a wireless interface device for interaction with a robot playmate.

Filed under: Rehab Centers

Conf Proc IEEE Eng Med Biol Soc. 2012 Aug; 2012: 6475-8
Roberts L, Park HW, Howard AM

Rehabilitation robots in home environments has the potential to dramatically improve quality of life for individuals who experience disabling circumstances due to injury or chronic health conditions. Unfortunately, although classes of robotic systems for rehabilitation exist, these devices are typically not designed for children. And since over 150 million children in the world live with a disability, this causes a unique challenge for deploying such robotics for this target demographic. To overcome this barrier, we discuss a system that uses a wireless arm glove input device to enable interaction with a robotic playmate during various play scenarios. Results from testing the system with 20 human subjects shows that the system has potential, but certain aspects need to be improved before deployment with children.
HubMed – rehab

 

Analysis of muscle fatigue induced by isometric vibration exercise at varying frequencies.

Filed under: Rehab Centers

Conf Proc IEEE Eng Med Biol Soc. 2012 Aug; 2012: 6463-6
Mischi M, Rabotti C, Cardinale M

An increase in neuromuscular activity, measured by electromyography (EMG), is usually observed during vibration exercise. The underlying mechanisms are however unclear, limiting the possibilities to introduce and exploit vibration training in rehabilitation programs. In this study, a new training device is used to perform vibration exercise at varying frequency and force, therefore enabling the analysis of the relationship between vibration frequency and muscle fatigue. Fatigue is estimated by maximum voluntary contraction measurement, as well as by EMG mean-frequency and conduction-velocity analysis. Seven volunteers performed five isometric contractions of the biceps brachii with a load consisting of a baseline of 80% of their maximum voluntary contraction (MVC), with no vibration and with a superimposed 20, 30, 40, and 50 Hz vibrational force of 40 N. Myoelectric and mechanical fatigue were estimated by EMG analysis and by assessment of the MVC decay, respectively. A dedicated motion artifact canceler, making use of accelerometry, is proposed to enable accurate EMG analysis. Use of this canceler leads to better interpolation of myoelectric fatigue trends and to better correlation between mechanical and myoelectric fatigue. In general, our results suggest vibration at 30 Hz to be the most fatiguing exercise. These results contribute to the analysis of vibration exercise and motivate further research aiming at improved training protocols.
HubMed – rehab

 

On the role of electric field orientation in optimal design of transcranial current stimulation.

Filed under: Rehab Centers

Conf Proc IEEE Eng Med Biol Soc. 2012 Aug; 2012: 6426-9
Dmochowski JP, Bikson M, Datta A, Richardson J, Fridriksson J, Parra LC

Transcranial current stimulation (tCS) is a promising noninvasive technique to elicit neuromodulation by passing weak electrical currents through scalp electrodes. While significant effort has been devoted towards designing stimulation protocols which “steer” current to regions of interest, previous work has been almost exclusively focused on the magnitude of the electric field, while ignoring the effects of direction. This is despite previous in vitro studies demonstrating that the angle between the field orientation and the cell axis of symmetry has significant effects on the resulting membrane polarization presumably underlying therapeutic effects. To that end, here we examine the impact of the desired electric field orientation on the optimal placement of electrodes for a given target region. Based on high-resolution head models derived from magnetic resonance scans of patients enrolled in a clinical trial examining the use of tCS in rehabilitation after stroke, we derive and employ an optimization algorithm which computes the montage maximizing directed current flow at the target. The results reveal a strong dependence of the optimal montage on the desired orientation; moreover, the magnitude of the induced electric field at the target region varies widely with the preferred direction. This suggests that identifying the desired electric field orientation at the region of interest is a crucial step in the development of rational electrical stimulation paradigms.
HubMed – rehab

 

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