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Lewis S.,Otto Bock Healthcare Products | Friedrich Russold M.,Otto Bock Healthcare Products | Dietl H.,Otto Bock Healthcare Products | Westendorff S.,German Primate Center | And 9 more authors.
2012 IEEE I2MTC - International Instrumentation and Measurement Technology Conference, Proceedings | Year: 2012

This work presents intramuscular measurements of the electromyogram (EMG) during goal directed arm movements. Thin film electrode arrays were epimysially implanted on the deltoideus of a rhesus macaque and the encapsulation process was monitored by impedance measurements. Increase of impedance plateaued after four weeks indicating a complete incorporation of electrodes. EMG recorded with these electrodes yielded a signal to noise ratio of about 80 dB at 200 Hz. The EMG recorded during goal directed arm movements showed high similarity amongst movements in the same direction while presenting clear differences between different movement directions. A second implantation of the whole measurement system for nine weeks proved good handling and biotolerance. © 2012 IEEE. Source


Dosen S.,University of Gottingen | Ninu A.,University of Gottingen | Yakimovich T.,Otto Bock Healthcare Products | Dietl H.,Otto Bock Healthcare Products | Farina D.,University of Gottingen
IEEE Transactions on Haptics | Year: 2016

The natural interaction of humans with their environment involves the harmonious coordination of the body, for which multi-modal feedback including vision, proprioception, and tactile perception is essential. Most human-machine interfaces, however, rely on the visual feedback only, and this can lead to considerable cognitive burden. Additional haptic feedback can increase the intuitiveness of the man-machine interaction. Therefore, we propose here a new device able to generate complex vibrotactile stimulation by simultaneously modulating the amplitude and frequency of vibration. Physical measurements were first performed in eight healthy subjects to assess the capability of the device to generate vibrations. The results indicated that the vibration frequency and amplitude can be independently modulated and that the device response to the full-range step-change in the amplitude/frequency commands is almost instantaneous and symmetric. In addition, psychophysical assessments were conducted in four healthy subjects using a standard psychophysical procedure (SIAM). The outcomes indicated that the proposed device can produce approximately 400 vixels (discriminable stimuli), which allow for the generation of a high diversity of vibrotactile patterns. The proposed method allows producing different kinds of stimulation patterns using motor types that are suited for specific applications, with adjustable trade-off between vibration intensity, size, and power consumption. © 2008-2011 IEEE. Source


Ninu A.,Otto Bock Healthcare Products | Ninu A.,University of Gottingen | Ninu A.,Institute for Analysis and Scientific Computing | Dosen S.,University of Gottingen | And 4 more authors.
IEEE Transactions on Neural Systems and Rehabilitation Engineering | Year: 2014

In closed-loop control of grasping by hand prostheses, the feedback information sent to the user is usually the actual controlled variable, i.e., the grasp force. Although this choice is intuitive and logical, the force production is only the last step in the process of grasping. Therefore, this study evaluated the performance in controlling grasp strength using a hand prosthesis operated through a complete grasping sequence while varying the feedback variables (e.g., closing velocity, grasping force), which were provided to the user visually or through vibrotactile stimulation. The experiments were conducted on 13 volunteers who controlled the Otto Bock Sensor Hand Speed prosthesis. Results showed that vibrotactile patterns were able to replace the visual feedback. Interestingly, the experiments demonstrated that direct force feedback was not essential for the control of grasping force. The subjects were indeed able to control the grip strength, predictively, by estimating the grasping force from the prosthesis velocity of closing. Therefore, grasping without explicit force feedback is not completely blind, contrary to what is usually assumed. In our study we analyzed grasping with a specific prosthetic device, but the outcomes are also applicable for other devices, with one or more degrees- of-freedom. The necessary condition is that the electromyography (EMG) signal directly and proportionally controls the velocity/ grasp force of the hand, which is a common approach among EMG controlled prosthetic devices. The results provide important indications on the design of closed-loop EMG controlled prosthetic systems. © 2014 IEEE. Source


Lewis S.,Otto Bock Healthcare Products | Russold M.,Otto Bock Healthcare Products | Dietl H.,Otto Bock Healthcare Products | Ruff R.,Fraunhofer Institute for Biomedical Engineering | And 9 more authors.
IEEE Transactions on Instrumentation and Measurement | Year: 2013

This paper presents intramuscular electromyogram (EMG) signals obtained with a fully implantable measurement system that were recorded during goal directed arm movements. In a first implantation thin film electrodes were epimysially implanted on the deltoideus of a rhesus macaque and the encapsulation process was monitored by impedance measurements. Increase of impedance reached a constant level after four weeks indicating a complete encapsulation of electrodes. EMG recorded with these electrodes yielded a signal-to-noise ratio of about 80 dB at 200 Hz. The EMG recorded during goal-directed arm movements showed a high similarity to movements in the same direction and at the same time presented clear differences between different movement directions in time domain. Six classifiers and seven time and frequency domain features were investigated with the aim of discriminating the direction of arm movement from EMG signals. Reliable recognition of arm movements was achieved for a subset of the movements under investigation only. A second implantation of the whole measurement system for nine weeks demonstrated simple handling during surgery and good biotolerance in the animals. © 1963-2012 IEEE. Source


Lewis S.,Otto Bock Healthcare Products | Russold M.F.,Otto Bock Healthcare Products | Dietl H.,Otto Bock Healthcare Products | Kaniusas E.,Vienna University of Technology
MeMeA 2012 - 2012 IEEE Symposium on Medical Measurements and Applications, Proceedings | Year: 2012

This paper presents the results of 108 responses to a survey asking users of electrical upper limb prostheses about sensory feedback. The survey aimed to identify whether sensory feedback was of interest to users, which kinds of information were important and what feedback modality would be suited for transfer of information. Moreover the situations in which sensory feedback would be most useful should be identified. To answer these questions we designed a survey which was sent by mail and was also available online. 88% of respondents placed different degree of importance on obtaining sensory feedback from their prosthesis. Grip force was most important followed by proprioceptive information. First contact during grasping and end of contact during release of an object was also of interest to respondents. Vibration, pressure and electrical stimulation were identified as appropriate means for transmission of sensory information from the prosthesis to the amputee, based on their acceptance and sensitivity at the residual limb. These findings allow conclusions for further development on what information has to be measured by feedback prostheses and how this information can be transmitted to the amputee. Investigation of perceptions respondents apply to control their current electrical prosthesis reveals that observation, listening and sensations at the residual limb are used and applied to gain certain information about the prosthesis. This could be the basis for a training of prosthesis users aiming at prosthesis control with less visual attention. © 2012 IEEE. Source

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