Trackhold: A Novel Passive Arm-Support Device

This article introduces the design and the experimental validation of the Trackhold, a novel mechanical motion-tracker for upper limb physical rehabilitation. The Trackhold is based on a passively balanced mechanism that can approximately relieve the weight of the patient’s arm regardless of the position. The system features a novel kinematic architecture with large workspace and custom developed joint sensors providing accurate real-time measure of the upper limb posture. The design approach of the device, which went through kinetostatic and dynamic analyses, is presented and details on the employed mechatronic solutions are provided. A prototype of the Trackhold has been fabricated and functionally validated.

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Evaluation of Optimal Vibrotactile Feedback for Force-Controlled Upper Limb Myoelectric Prostheses

Sensors ◽

10.3390/s19235209 ◽

2019 ◽

Vol 19 (23) ◽

pp. 5209 ◽

Cited By ~ 1

Author(s):

Andrea Gonzalez-Rodriguez ◽

Jose L. Ramon ◽

Vicente Morell ◽

Gabriel J. Garcia ◽

Jorge Pomares ◽

...

Keyword(s):

Real Time ◽

Upper Limb ◽

Closed Loop ◽

Fine Tuning ◽

Vibrotactile Feedback ◽

Loop Control ◽

Myoelectric Prostheses ◽

Amplitude Level ◽

Real Time Application ◽

Selection Of

The main goal of this study is to evaluate how to optimally select the best vibrotactile pattern to be used in a closed loop control of upper limb myoelectric prostheses as a feedback of the exerted force. To that end, we assessed both the selection of actuation patterns and the effects of the selection of frequency and amplitude parameters to discriminate between different feedback levels. A single vibrotactile actuator has been used to deliver the vibrations to subjects participating in the experiments. The results show no difference between pattern shapes in terms of feedback perception. Similarly, changes in amplitude level do not reflect significant improvement compared to changes in frequency. However, decreasing the number of feedback levels increases the accuracy of feedback perception and subject-specific variations are high for particular participants, showing that a fine-tuning of the parameters is necessary in a real-time application to upper limb prosthetics. In future works, the effects of training, location, and number of actuators will be assessed. This optimized selection will be tested in a real-time proportional myocontrol of a prosthetic hand.

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Differences in muscular activation and fatigue for intermittent and constant load

Occupational Ergonomics ◽

10.3233/oer-2005-5105 ◽

2005 ◽

Vol 5 (1) ◽

pp. 43-56

Author(s):

Danuta Roman-Liu ◽

Krzysztof Kȩdzior

Keyword(s):

External Force ◽

Upper Limb ◽

Muscle Activation ◽

Regression Line ◽

Constant Load ◽

Median Frequency ◽

Experimental Conditions ◽

Emg Signal ◽

Limb Posture ◽

Muscular Activation

The aim of this study was to compare the influence of constant or intermittent load on muscle activation and fatigue. The analysis and assessment of muscular activation and fatigue was based on surface EMG measurements from eight muscles (seven muscles of the right upper limb and trapezius muscle). Two EMG signal parameters were analyzed for each of the experimental conditions distinguished by the value of the external force and the character of the load – constant or intermittent. The amplitude related to its maximum (AMP) and the slope of the regression line between time and median frequency (SMF) were the EMG parameters that were analyzed. The results showed that constant load caused higher muscular fatigue than intermittent load despite the lower value of the external force and lower muscle activation. Results suggest that additional external force might influence muscle activation and fatigue more than upper limb posture. The results of the study support the thesis that all biomechanical factors which influence upper limb load and fatigue (upper limb posture, external force and time sequences) should be considered when work stands and work processes are designed. They also indicate that constant load should be especially avoided.

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