TPress

@article{Volkmar2019,

title = {Improving bimanual interaction with a prosthesis using semi-autonomous control},

author = {R. Volkmar and S. Dosen and J. Gonzalez-Vargas and M. Baum and M. Markovic},

url = {https://www.embase.com/search/results?subaction=viewrecord&id=L629849607&from=export},

doi = {10.1186/s12984-019-0617-6},

issn = {1743-0003},

year  = {2019},

date = {2019-01-01},

journal = {J. NeuroEng. Rehabil.},

volume = {16},

number = {1},

address = {M. Markovic, Department of Trauma Surgery Orthopedics and Plastic Surgery, University Medical Center Göttingen, Von-Siebold-Str. 3, Göttingen, Germany},

abstract = {Background: The loss of a hand is a traumatic experience that substantially compromises an individual's capability to interact with his environment. The myoelectric prostheses are state-of-the-art (SoA) functional replacements for the lost limbs. Their overall mechanical design and dexterity have improved over the last few decades, but the users have not been able to fully exploit these advances because of the lack of effective and intuitive control. Bimanual tasks are particularly challenging for an amputee since prosthesis control needs to be coordinated with the movement of the sound limb. So far, the bimanual activities have been often neglected by the prosthetic research community. Methods: We present a novel method to prosthesis control, which uses a semi-autonomous approach in order to simplify bimanual interactions. The approach supplements the commercial SoA two-channel myoelectric control with two additional sensors. Two inertial measurement units were attached to the prosthesis and the sound hand to detect the movement of both limbs. Once a bimanual interaction is detected, the system mimics the coordination strategies of able-bodied subjects to automatically adjust the prosthesis wrist rotation (pronation, supination) and grip type (lateral, palmar) to assist the sound hand during a bimanual task. The system has been evaluated in eight able-bodied subjects performing functional uni- A nd bi-manual tasks using the novel method and SoA two-channel myocontrol. The outcome measures were time to accomplish the task, semi-autonomous system misclassification rate, subjective rating of intuitiveness, and perceived workload (NASA TLX). Results: The results demonstrated that the novel control interface substantially outperformed the SoA myoelectric control. While using the semi-autonomous control the time to accomplish the task and the perceived workload decreased for 25 and 27%, respectively, while the subjects rated the system as more intuitive then SoA myocontrol. Conclusions: The novel system uses minimal additional hardware (two inertial sensors) and simple processing and it is therefore convenient for practical implementation. By using the proposed control scheme, the prosthesis assists the user's sound hand in performing bimanual interactions while decreasing cognitive burden.},

keywords = {adult, analytical equipment, article, bimanual interaction, controlled study, female, hand prosthesis, human, human experiment, inertial sensor, limb movement, male, motor control, motor performance, outcome assessment, priority journal, prosthesis, prosthesis design, semi autonomous control, sensor, task performance, vibrotactor, workload},

pubstate = {published},

tppubtype = {article}

}

@article{Ernst2017,

title = {Standing on slopes - How current microprocessor-controlled prosthetic feet support transtibial and transfemoral amputees in an everyday task},

author = {M. Ernst and B. Altenburg and M. Bellmann and T. Schmalz},

url = {https://www.embase.com/search/results?subaction=viewrecord&id=L619264869&from=export},

doi = {10.1186/s12984-017-0322-2},

issn = {1743-0003},

year  = {2017},

date = {2017-01-01},

journal = {J. NeuroEng. Rehabil.},

volume = {14},

number = {1},

address = {M. Ernst, Research Biomechanics, CRandS, Otto Bock HealthCare GmbH, Göttingen, Germany},

abstract = {Background: Conventional prosthetic feet like energy storage and return feet provide only a limited range of ankle motion compared to human ones. In order to overcome the poor rotational adaptability, prosthetic manufacturers developed different prosthetic feet with an additional rotational joint and implemented active control in different states. It was the aim of the study to investigate to what extent these commercially available microprocessor-controlled prosthetic feet support a natural posture while standing on inclines and which concept is most beneficial for lower limb amputees. Methods: Four unilateral transtibial and four unilateral transfemoral amputees participated in the study. Each of the subjects wore five different microprocessor-controlled prosthetic feet in addition to their everyday feet. The subjects were asked to stand on slopes of different inclinations (level ground, upward slope of 10°, and downward slope of -10°). Vertical ground reaction forces, joint torques and joint angles in the sagittal plane were measured for both legs separately for the different situations and compared to a non-amputee reference group. Results: Differences in the biomechanical parameters were observed between the different prosthetic feet and compared to the reference group for the investigated situations. They were most prominent while standing on a downward slope. For example, on the prosthetic side, the vertical ground reaction force is reduced by about 20%, and the torque about the knee acts to flex the joint for feet that are not capable of a full adaptation to the downward slope. In contrast, fully adaptable feet with an auto-adaptive dorsiflexion stop show no changes in vertical ground reaction forces and knee extending torques. Conclusions: A prosthetic foot that provides both, an auto-adaptive dorsiflexion stop and a sufficient range of motion for fully adapting to inclinations appears to be the key element in the prosthetic fitting for standing on inclinations in lower limb amputees. In such situations, this prosthetic concept appears superior to both, conventional feet with passive structures as well as feet that solely provide a sufficient range of motion. The results also indicate that both, transfemoral and transtibial amputees benefit from such a foot.},

keywords = {adult, article, autoadaptive dorsiflexion stop, controlled study, foot prosthesis, Genium, ground reaction force, human, human experiment, informed consent, joint angle, joint torque, leg amputation, male, microprocessor, microprocessor controlled prosthetic feet, musculoskeletal function, musculoskeletal system parameters, priority journal, standing, task performance, transfemoral amputation, transtibial amputation, vertical ground reaction force},

pubstate = {published},

tppubtype = {article}

}

@article{Schweisfurth2016,

title = {Electrotactile EMG feedback improves the control of prosthesis grasping force},

author = {M. A. Schweisfurth and M. Markovic and S. Dosen and F. Teich and B. Graimann and D. Farina},

url = {https://www.embase.com/search/results?subaction=viewrecord&id=L612465506&from=export},

doi = {10.1088/1741-2560/13/5/056010},

issn = {1741-2560},

year  = {2016},

date = {2016-01-01},

journal = {J. Neural Eng.},

volume = {13},

number = {5},

address = {D. Farina, Institute for NeuroRehabilitation Systems, University Medical Center Göttingen, Georg-August University, Göttingen, Germany},

abstract = {Objective. A drawback of active prostheses is that they detach the subject from the produced forces, thereby preventing direct mechanical feedback. This can be compensated by providing somatosensory feedback to the user through mechanical or electrical stimulation, which in turn may improve the utility, sense of embodiment, and thereby increase the acceptance rate. Approach. In this study, we compared a novel approach to closing the loop, namely EMG feedback (emgFB), to classic force feedback (forceFB), using electrotactile interface in a realistic task setup. Eleven intact-bodied subjects and one transradial amputee performed a routine grasping task while receiving emgFB or forceFB. The two feedback types were delivered through the same electrotactile interface, using a mixed spatial/frequency coding to transmit 8 discrete levels of the feedback variable. In emgFB, the stimulation transmitted the amplitude of the processed myoelectric signal generated by the subject (prosthesis input), and in forceFB the generated grasping force (prosthesis output). The task comprised 150 trials of routine grasping at six forces, randomly presented in blocks of five trials (same force). Interquartile range and changes in the absolute error (AE) distribution (magnitude and dispersion) with respect to the target level were used to assess precision and overall performance, respectively. Main results. Relative to forceFB, emgFB significantly improved the precision of myoelectric commands (min/max of the significant levels) for 23%/36% as well as the precision of force control for 12%/32%, in intact-bodied subjects. Also, the magnitude and dispersion of the AE distribution were reduced. The results were similar in the amputee, showing considerable improvements. Significance. Using emgFB, the subjects therefore decreased the uncertainty of the forward pathway. Since there is a correspondence between the EMG and force, where the former anticipates the latter, the emgFB allowed for predictive control, as the subjects used the feedback to adjust the desired force even before the prosthesis contacted the object. In conclusion, the online emgFB was superior to the classic forceFB in realistic conditions that included electrotactile stimulation, limited feedback resolution (8 levels), cognitive processing delay, and time constraints (fast grasping).},

keywords = {accuracy, adult, amputee, article, case report, controlled study, electromyography, electrotactile electromyography, feedback system, female, force, grip strength, hand prosthesis, human, Michaelangelo Hand, myoelectrically controlled prosthesis, priority journal, sensory feedback, task performance, young adult},

pubstate = {published},

tppubtype = {article}

}

@article{Wit2004,

title = {The effect of an ankle-foot orthosis on walking ability in chronic stroke patients: A randomized controlled trial},

author = {D. C. M. Wit and J. H. Buurke and J. M. M. Nijlant and M. J. IJzerman and H. J. Hermens},

url = {https://www.embase.com/search/results?subaction=viewrecord&id=L39076880&from=export},

doi = {10.1191/0269215504cr770oa},

issn = {0269-2155},

year  = {2004},

date = {2004-01-01},

journal = {Clin. Rehabil.},

volume = {18},

number = {5},

pages = {550–557},

address = {D.C.M. de Wit, Roessingh Research and Development, Roessinghbleekweg 33B, 7522 AH Enschede, Netherlands},

abstract = {Objective: Regaining walking ability is a major goal during the rehabilitation of stroke patients. To support this process an ankle-foot orthosis (AFC) is often prescribed. The aim of this study is to investigate the effect of an AFO on walking ability in chronic stroke patients. Design: Cross-over design with randomization for the interventions. Methods: Twenty chronic stroke patients, wearing an AFO for at least six months, were included. Walking ability was operationalized as comfortable walking speed, scores on the timed up and go (TUG) test and stairs test. Patients were measured with and without their AFO, the sequence of which was randomized. Additionally, subjective impressions of self-confidence and difficulty of the tasks were scored. Clinically relevant differences based on literature were defined for walking speed (20 cm/s), the TUG test (10 s). Gathered data were statistically analysed using a paired t-test. Results: The mean difference in favour of the AFO in walking speed was 4.8 cm/s (95% CI 0.85-8.7), in the TUG test 3.6 s (95% CI 2.4-4.8) and in the stairs test 8.6 s (95% CI 3.1-14.1). Sixty-five per cent of the patients experienced less difficulty and 70% of the patients felt more self-confident while wearing the AFO. Conclusions: The effect of an AFO on walking ability is statistically significant, but compared with the a priori defined differences it is too small to be clinically relevant. The effect on self-confidence suggests that other factors might play an important role in the motivation to use an AFO. © Arnold 2004.},

keywords = {adult, aged, article, Camp, cerebrovascular accident, chronic disease, climbing, clinical article, clinical trial, controlled clinical trial, controlled study, crossover procedure, Distrac, Dynafo, female, gait disorder, human, male, motivation, motor performance, orthosis, Ottobock, randomized controlled trial, scoring system, self esteem, standing, statistical analysis, task performance, walking speed},

pubstate = {published},

tppubtype = {article}

}

@article{Volkmar2019,

title = {Improving bimanual interaction with a prosthesis using semi-autonomous control},

author = {R. Volkmar and S. Dosen and J. Gonzalez-Vargas and M. Baum and M. Markovic},

url = {https://www.embase.com/search/results?subaction=viewrecord&id=L629849607&from=export},

doi = {10.1186/s12984-019-0617-6},

issn = {1743-0003},

year  = {2019},

date = {2019-01-01},

journal = {J. NeuroEng. Rehabil.},

volume = {16},

number = {1},

address = {M. Markovic, Department of Trauma Surgery Orthopedics and Plastic Surgery, University Medical Center Göttingen, Von-Siebold-Str. 3, Göttingen, Germany},

abstract = {Background: The loss of a hand is a traumatic experience that substantially compromises an individual's capability to interact with his environment. The myoelectric prostheses are state-of-the-art (SoA) functional replacements for the lost limbs. Their overall mechanical design and dexterity have improved over the last few decades, but the users have not been able to fully exploit these advances because of the lack of effective and intuitive control. Bimanual tasks are particularly challenging for an amputee since prosthesis control needs to be coordinated with the movement of the sound limb. So far, the bimanual activities have been often neglected by the prosthetic research community. Methods: We present a novel method to prosthesis control, which uses a semi-autonomous approach in order to simplify bimanual interactions. The approach supplements the commercial SoA two-channel myoelectric control with two additional sensors. Two inertial measurement units were attached to the prosthesis and the sound hand to detect the movement of both limbs. Once a bimanual interaction is detected, the system mimics the coordination strategies of able-bodied subjects to automatically adjust the prosthesis wrist rotation (pronation, supination) and grip type (lateral, palmar) to assist the sound hand during a bimanual task. The system has been evaluated in eight able-bodied subjects performing functional uni- A nd bi-manual tasks using the novel method and SoA two-channel myocontrol. The outcome measures were time to accomplish the task, semi-autonomous system misclassification rate, subjective rating of intuitiveness, and perceived workload (NASA TLX). Results: The results demonstrated that the novel control interface substantially outperformed the SoA myoelectric control. While using the semi-autonomous control the time to accomplish the task and the perceived workload decreased for 25 and 27%, respectively, while the subjects rated the system as more intuitive then SoA myocontrol. Conclusions: The novel system uses minimal additional hardware (two inertial sensors) and simple processing and it is therefore convenient for practical implementation. By using the proposed control scheme, the prosthesis assists the user's sound hand in performing bimanual interactions while decreasing cognitive burden.},

keywords = {adult, analytical equipment, article, bimanual interaction, controlled study, female, hand prosthesis, human, human experiment, inertial sensor, limb movement, male, motor control, motor performance, outcome assessment, priority journal, prosthesis, prosthesis design, semi autonomous control, sensor, task performance, vibrotactor, workload},

pubstate = {published},

tppubtype = {article}

}

@article{Ernst2017,

title = {Standing on slopes - How current microprocessor-controlled prosthetic feet support transtibial and transfemoral amputees in an everyday task},

author = {M. Ernst and B. Altenburg and M. Bellmann and T. Schmalz},

url = {https://www.embase.com/search/results?subaction=viewrecord&id=L619264869&from=export},

doi = {10.1186/s12984-017-0322-2},

issn = {1743-0003},

year  = {2017},

date = {2017-01-01},

journal = {J. NeuroEng. Rehabil.},

volume = {14},

number = {1},

address = {M. Ernst, Research Biomechanics, CRandS, Otto Bock HealthCare GmbH, Göttingen, Germany},

abstract = {Background: Conventional prosthetic feet like energy storage and return feet provide only a limited range of ankle motion compared to human ones. In order to overcome the poor rotational adaptability, prosthetic manufacturers developed different prosthetic feet with an additional rotational joint and implemented active control in different states. It was the aim of the study to investigate to what extent these commercially available microprocessor-controlled prosthetic feet support a natural posture while standing on inclines and which concept is most beneficial for lower limb amputees. Methods: Four unilateral transtibial and four unilateral transfemoral amputees participated in the study. Each of the subjects wore five different microprocessor-controlled prosthetic feet in addition to their everyday feet. The subjects were asked to stand on slopes of different inclinations (level ground, upward slope of 10°, and downward slope of -10°). Vertical ground reaction forces, joint torques and joint angles in the sagittal plane were measured for both legs separately for the different situations and compared to a non-amputee reference group. Results: Differences in the biomechanical parameters were observed between the different prosthetic feet and compared to the reference group for the investigated situations. They were most prominent while standing on a downward slope. For example, on the prosthetic side, the vertical ground reaction force is reduced by about 20%, and the torque about the knee acts to flex the joint for feet that are not capable of a full adaptation to the downward slope. In contrast, fully adaptable feet with an auto-adaptive dorsiflexion stop show no changes in vertical ground reaction forces and knee extending torques. Conclusions: A prosthetic foot that provides both, an auto-adaptive dorsiflexion stop and a sufficient range of motion for fully adapting to inclinations appears to be the key element in the prosthetic fitting for standing on inclinations in lower limb amputees. In such situations, this prosthetic concept appears superior to both, conventional feet with passive structures as well as feet that solely provide a sufficient range of motion. The results also indicate that both, transfemoral and transtibial amputees benefit from such a foot.},

keywords = {adult, article, autoadaptive dorsiflexion stop, controlled study, foot prosthesis, Genium, ground reaction force, human, human experiment, informed consent, joint angle, joint torque, leg amputation, male, microprocessor, microprocessor controlled prosthetic feet, musculoskeletal function, musculoskeletal system parameters, priority journal, standing, task performance, transfemoral amputation, transtibial amputation, vertical ground reaction force},

pubstate = {published},

tppubtype = {article}

}

@article{Schweisfurth2016,

title = {Electrotactile EMG feedback improves the control of prosthesis grasping force},

author = {M. A. Schweisfurth and M. Markovic and S. Dosen and F. Teich and B. Graimann and D. Farina},

url = {https://www.embase.com/search/results?subaction=viewrecord&id=L612465506&from=export},

doi = {10.1088/1741-2560/13/5/056010},

issn = {1741-2560},

year  = {2016},

date = {2016-01-01},

journal = {J. Neural Eng.},

volume = {13},

number = {5},

address = {D. Farina, Institute for NeuroRehabilitation Systems, University Medical Center Göttingen, Georg-August University, Göttingen, Germany},

abstract = {Objective. A drawback of active prostheses is that they detach the subject from the produced forces, thereby preventing direct mechanical feedback. This can be compensated by providing somatosensory feedback to the user through mechanical or electrical stimulation, which in turn may improve the utility, sense of embodiment, and thereby increase the acceptance rate. Approach. In this study, we compared a novel approach to closing the loop, namely EMG feedback (emgFB), to classic force feedback (forceFB), using electrotactile interface in a realistic task setup. Eleven intact-bodied subjects and one transradial amputee performed a routine grasping task while receiving emgFB or forceFB. The two feedback types were delivered through the same electrotactile interface, using a mixed spatial/frequency coding to transmit 8 discrete levels of the feedback variable. In emgFB, the stimulation transmitted the amplitude of the processed myoelectric signal generated by the subject (prosthesis input), and in forceFB the generated grasping force (prosthesis output). The task comprised 150 trials of routine grasping at six forces, randomly presented in blocks of five trials (same force). Interquartile range and changes in the absolute error (AE) distribution (magnitude and dispersion) with respect to the target level were used to assess precision and overall performance, respectively. Main results. Relative to forceFB, emgFB significantly improved the precision of myoelectric commands (min/max of the significant levels) for 23%/36% as well as the precision of force control for 12%/32%, in intact-bodied subjects. Also, the magnitude and dispersion of the AE distribution were reduced. The results were similar in the amputee, showing considerable improvements. Significance. Using emgFB, the subjects therefore decreased the uncertainty of the forward pathway. Since there is a correspondence between the EMG and force, where the former anticipates the latter, the emgFB allowed for predictive control, as the subjects used the feedback to adjust the desired force even before the prosthesis contacted the object. In conclusion, the online emgFB was superior to the classic forceFB in realistic conditions that included electrotactile stimulation, limited feedback resolution (8 levels), cognitive processing delay, and time constraints (fast grasping).},

keywords = {accuracy, adult, amputee, article, case report, controlled study, electromyography, electrotactile electromyography, feedback system, female, force, grip strength, hand prosthesis, human, Michaelangelo Hand, myoelectrically controlled prosthesis, priority journal, sensory feedback, task performance, young adult},

pubstate = {published},

tppubtype = {article}

}

@article{Wit2004,

title = {The effect of an ankle-foot orthosis on walking ability in chronic stroke patients: A randomized controlled trial},

author = {D. C. M. Wit and J. H. Buurke and J. M. M. Nijlant and M. J. IJzerman and H. J. Hermens},

url = {https://www.embase.com/search/results?subaction=viewrecord&id=L39076880&from=export},

doi = {10.1191/0269215504cr770oa},

issn = {0269-2155},

year  = {2004},

date = {2004-01-01},

journal = {Clin. Rehabil.},

volume = {18},

number = {5},

pages = {550–557},

address = {D.C.M. de Wit, Roessingh Research and Development, Roessinghbleekweg 33B, 7522 AH Enschede, Netherlands},

abstract = {Objective: Regaining walking ability is a major goal during the rehabilitation of stroke patients. To support this process an ankle-foot orthosis (AFC) is often prescribed. The aim of this study is to investigate the effect of an AFO on walking ability in chronic stroke patients. Design: Cross-over design with randomization for the interventions. Methods: Twenty chronic stroke patients, wearing an AFO for at least six months, were included. Walking ability was operationalized as comfortable walking speed, scores on the timed up and go (TUG) test and stairs test. Patients were measured with and without their AFO, the sequence of which was randomized. Additionally, subjective impressions of self-confidence and difficulty of the tasks were scored. Clinically relevant differences based on literature were defined for walking speed (20 cm/s), the TUG test (10 s). Gathered data were statistically analysed using a paired t-test. Results: The mean difference in favour of the AFO in walking speed was 4.8 cm/s (95% CI 0.85-8.7), in the TUG test 3.6 s (95% CI 2.4-4.8) and in the stairs test 8.6 s (95% CI 3.1-14.1). Sixty-five per cent of the patients experienced less difficulty and 70% of the patients felt more self-confident while wearing the AFO. Conclusions: The effect of an AFO on walking ability is statistically significant, but compared with the a priori defined differences it is too small to be clinically relevant. The effect on self-confidence suggests that other factors might play an important role in the motivation to use an AFO. © Arnold 2004.},

keywords = {adult, aged, article, Camp, cerebrovascular accident, chronic disease, climbing, clinical article, clinical trial, controlled clinical trial, controlled study, crossover procedure, Distrac, Dynafo, female, gait disorder, human, male, motivation, motor performance, orthosis, Ottobock, randomized controlled trial, scoring system, self esteem, standing, statistical analysis, task performance, walking speed},

pubstate = {published},

tppubtype = {article}

}