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--- start [2020/05/08 17:02]
Maziar Sharbafi
+++ start [2020/08/24 10:15]
Martin Grimmer [A biarticular passive exosuit to support balance control can reduce metabolic cost of walking]
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 ====== Latest Publications ======
+==== Doppler Radar for the Extraction of Biomechanical Parameters in Gait Analysis  ====
+Doppler Radar for the extraction of biomechanical parameters during walking was investigated in one of our latest studies in cooperation with the Signal Processing Group of Prof. Zoubir. Ann-Kathrin Seifert and [[lab_members:lab_members_martingrimmer|Martin Grimmer]]performed a series of experiments in the Locomotion Laboratory. The work was recently published in the[[https://doi.org/10.1109/jbhi.2020.2994471| IEEE Journal of Biomedical and Health Informatics]].
+{{ ::radar.jpg?600|}}
+**Abstract:**
+The applicability of Doppler radar for gait analysis is investigated by quantitatively comparing the measured biomechanical parameters to those obtained using motion capturing
+and ground reaction forces. Nineteen individuals walked on a treadmill at two different speeds, where a radar system was positioned in front of or behind the subject. The right knee angle was confined by an adjustable orthosis in five different degrees. Eleven gait parameters are extracted from radar micro-Doppler signatures. Here, new methods for obtaining the velocities of individual lower limb joints are proposed. Further, a new method to extract individual leg flight times from radar data is introduced. Based on radar data, five spatiotemporal parameters related to rhythm and pace could reliably be extracted. Further,
+for most of the considered conditions, three kinematic parameters could accurately be measured. The radar-based stance and flight time measurements rely on the correct detection of the time instant of maximal knee velocity during the gait cycle. This time instant is reliably detected when the radar has a back view, but is underestimated when the radar is positioned in front of the subject. The results validate the applicability of Doppler radar to accurately measure a variety of medically relevant gait parameters. Radar has the potential to unobtrusively diagnose changes in gait, e.g., to design training in prevention and rehabilitation. As contact-less and privacy-preserving sensor, radar presents aviable technology to supplement existing gait analysis tools for long-term in-home examinations.
+For further projects and publications of [[lab_members:lab_members_martingrimmer|M. Grimmer]] please check: [[https://www.researchgate.net/profile/Martin_Grimmer3|ResearchGate]], [[https://scholar.google.de/citations?hl=de&user=gDF_uHUAAAAJ&view_op=list_works&sortby=pubdate|Google Scholar]], [[https://orcid.org/0000-0003-1921-1433|ORCID]] or [[https://loop.frontiersin.org/people/390560/overview|LOOP]]
 ==== A biarticular passive exosuit to support balance control can reduce metabolic cost of walking ====
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 Leg morphology is an important outcome of evolution. A remarkable morphological leg feature is the existence of biarticular muscles that span adjacent joints. Diverse studies from different fields of research suggest a less coherent understanding of the muscles’ functionality in cyclic, sagittal plane locomotion. We structured this review of biarticular muscle function by reflecting biomechanical template models, human experiments and robotic system designs. Within these approaches, we surveyed the contribution of biarticular muscles to the locomotor subfunctions (stance, balance and swing). While mono- and biarticular muscles do not show physiological differences, the reviewed studies provide evidence for complementary and locomotor subfunction-specific contributions of mono- and biarticular muscles. In stance, biarticular muscles coordinate joint movements, improve economy (e.g. by transferring energy) and secure the zig-zag configuration of the leg against joint overextension. These commonly known functions are extended by an explicit role of biarticular muscles in controlling the angular momentum for balance and swing. Human-like leg arrangement and intrinsic (compliant) properties of biarticular structures improve the controllability and energy efficiency of legged robots and assistive devices. Future interdisciplinary research on biarticular muscles should address their role for sensing and control as well as non-cyclic and/or non-sagittal motions, and non-static moment arms. \\
-==== Human Lower Limb Joint Biomechanics in Daily Life Activities: A Literature Based Requirement Analysis for Anthropomorphic Robot Design  ====
-Human lower limb biomechanics of daily activities were investigated in one of our latest studies by [[lab_members:lab_members_martingrimmer|Martin Grimmer]], Ahmed Elshamanhory and Philipp Beckerle. The work was recently published in [[https://doi.org/10.3389/frobt.2020.00013|Frontiers in Robotics and AI]]. The analyzed data is available as supplementary material [[https://www.frontiersin.org/articles/10.3389/frobt.2020.00013/full#supplementary-material|Matlab file]].
-{{ ::human_range_of_motion.jpg?600|}}
-**Abstract:**
-Daily human activity is characterized by a broad variety of movement tasks. This work summarizes the sagittal hip, knee, and ankle joint biomechanics for a broad range of daily movements, based on previously published literature, to identify requirements for robotic design. Maximum joint power, moment, angular velocity, and angular acceleration, as well as the movement-related range of motion and the mean absolute power were extracted, compared, and analyzed for essential and sportive movement tasks. We found that the full human range of motion is required to mimic human like performance and versatility. In general, sportive movements were found to exhibit the highest joint requirements in angular velocity, angular acceleration, moment, power, and mean absolute power. However, at the hip, essential movements, such as recovery, had comparable or even higher requirements. Further, we found that the moment and power demands were generally higher in stance, while the angular velocity and angular acceleration were mostly higher or equal in swing compared to stance for locomotion tasks. The extracted requirements provide a novel comprehensive overview that can help with the dimensioning of actuators enabling tailored assistance or rehabilitation for wearable lower limb robots, and to achieve essential, sportive or augmented performances that exceed natural human capabilities with humanoid robots.
-For further projects and publications of [[lab_members:lab_members_martingrimmer|M. Grimmer]] please check: [[https://www.researchgate.net/profile/Martin_Grimmer3|ResearchGate]], [[https://scholar.google.de/citations?hl=de&user=gDF_uHUAAAAJ&view_op=list_works&sortby=pubdate|Google Scholar]], [[https://orcid.org/0000-0003-1921-1433|ORCID]] or [[https://loop.frontiersin.org/people/390560/overview|LOOP]]
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