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This paper describes an experimental study which relates the simultaneous biceps/triceps surface electromyogram (EMG) of 12 subjects to elbow torque at seven joint angles during constant-posture, quasi-constant-torque contractions. Advanced EMG amplitude (EMGσ) estimation processors were investigated, and an EMG-torque model considering agonist and antagonist co-contractions was evaluated at each...
The surface electromyogram (EMG) from biceps/triceps muscles of 33 subjects was related to elbow torque, contrasting EMG amplitude (EMGσ) estimation processors, linear/non-linear model structures and system identification techniques. EMG-torque performance was improved by: advanced (i.e., whitened, multiple-channel) EMGσ processors; longer duration training sets (52 s vs. 26 s); and determination...
This project focuses on the development of robot-assisted stroke rehabilitation by implementing electromyography (EMG) as the interface between robot and user communication. Key issue in implementation of EMG in this application is conversion of EMG signal into torque data. This paper presents a methodology of EMG signal to estimated joint torque conversion by using genetic algorithm (GA). Basic principle...
The present study investigates the behavior of action potential conduction velocity (CV) on each repetition of an isokinetic test set and on each set as a whole. A total of seven healthy men (27.7 ± 2.8 yrs, 1.74 ± 0.06 m, and 79.6 ± 11.0 Kg) performed 3 (three) sets of 10 (ten) maximal concentric repetitions of dominant knee extension at 60°/s on an isokinetic dynamometer, with 1 minute of rest interval...
A musculoskeletal model of wrist flexors comprising musculoskeletal dynamics and limb anatomy was experimentally validated with healthy subjects during maximum voluntary contractions. Electromyography signals recorded from flexors were used as input, while measured torques exerted by the hand were compared to the torques predicted by the model. The root mean square error and the normalized root mean...
Biofeedback signals have been frequently used for rehabilitation purposes, and in design and calibration of orthotic and prosthetic devices. Whenever one or a couple of muscles of a joint are chosen for rehabilitation or control of a device, it's assumed that a specific load sharing or activation pattern exists among them for each individual and for each specific joint demand. Indeterminacy or a load...
In this paper, we propose a method for realtime estimation of whole-body muscle tensions. The main problem of muscle tension estimation is that there are infinite number of solutions to realize a particular joint torque due to the actuation redundancy. Numerical optimization techniques, e.g. quadratic programming, are often employed to obtain a unique solution, but they are usually computationally...
Given the impaired motor output of the lower limb post-stroke, we argue that cortical damage alters the modular control structure underlying muscle activation patterns during both static and dynamic tasks. Muscle synergies were extracted from EMG collected during isometric hip torque production performed by chronic stroke and control subjects. The stroke group presented a reduction in muscle synergies,...
This paper presents a robotic arm for stroke patients. Two SEMG (Surface Electromyography) signals collected from bicipital muscle and triceps muscle of arm, which are used to control robotic arm. When patients want to flexile arm, the SEMG signal of bicipital muscle is larger than that of triceps muscle. On the other hand, when patient want to extend arm, the SEMG signal of triceps muscle is larger...
In this paper, we propose a new method to make a quantitative evaluation of motor commands based on the EMG signals. Especially, we tried to resolve a remaining issue in our previous study: relatively poor estimation of the wrist joint torque from the EMG signals for extreme movements, such as jerky movements of the cerebellar patients. Subjects included eight cerebellar patients and eight normal...
The paper explores the application of instantaneous frequency (IF) analysis on EMG signals measured voluntarily across a period of 10 week physical training. The aim is to explore the effects of training on the muscle fiber recruitment strategy. The findings are presented and discussed, which suggest a link between training and motor unit synchronization. The paper also show-cases the effectiveness...
Numerous researchers have investigated the relationship between EMG and joint torque. Most of these studies use some conventional filtering (i.e. rectification followed by low pass filtering) to estimate the electromyogram (EMG) amplitude and then relate it to the joint torque. Currently some advanced pre-processing techniques (i.e. signal whitening) are also used to estimate the EMG amplitude and...
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