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--- start [2019/06/18 10:41]
Maziar Sharbafi [Concerted control concept in locomotion]
+++ start [2019/08/14 14:21]
Christian [News]
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 <slider :media:pako.jpg>
-===== Prosthesis =====
+===== Prostheses =====
 To investigate models of the muscle-tendon dynamics on humans we developed the research platform [[projects:projects_prostheses|PAKO]]. Using our insights on gait biomechanics, walking and running could be realized with the robotic [[projects:projects_walkrunankle|Walk-Run Ankle]] prosthesis.
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 ====== News ======
-  * **Movement Academy on Parkinson Gait** The Lauflabor organizes the [[http://wiki.ifs-tud.de/biomechanik/aktuelle_themen/bewak2019|first movement academy]] in Darmstadt on June 4 and 5, 2019
+  * {{::ansymb_logo_i.png?90 | Teaching course ANSYMB II}} **Running upcoming winter term!** [[http://www.ansymb.tu-darmstadt.de/|   Analysis and Synthesis of Human Movements]]
+====== Pick of the Month  ======
-  * **Dynamic Walking 2019** is announced! Click [[http://dynamicwalking.org/index.php/dw/2019|here]] for details.
-  * **Lauflabor Best Student Thesis Award 2018** Apply now until June 30, 2019. Click here for details: {{ :ll02_best_thesis_award18.pdf | Flyer }}
+==== Stance and Swing Detection Based on the Angular Velocity of Lower Limb Segments During Walking  ====
-  * {{::ansymb_logo_i.png?90 | Teaching course ANSYMB II}} **Running this summer term!** [[http://www.ansymb.tu-darmstadt.de/|   Analysis and Synthesis of Human Movements]]
-====== Pick of the Month  ======
-==== Concerted control concept in locomotion  ====
+A new concept for stance and swing detection based on lower limb segments is introduced in a recently published paper by Grimmer et al. in //Frontiers in Neurorobotics// [[https://www.frontiersin.org/articles/10.3389/fnbot.2019.00057/full?&utm_source=Email_to_authors_&utm_medium=Email&utm_content=T1_11.5e1_author&utm_campaign=Email_publication&field=&journalName=Frontiers_in_Neurorobotics&id=459435|Stance and Swing Detection Based on the Angular Velocity of Lower Limb Segments During Walking]].
-{{ :templatetoanchor.png?nolink&500|}}
-A new level of modelling evolution is introduced with replacing springs by muscle models in our recently published paper in the //Royal Society Open Science// journal titled [[https://doi.org/10.1098/rsos.181911|From template to anchors: transfer of virtual pendulum posture control balance template to adaptive neuromuscular gait model increases walking stability]].
+{{ :stance_swing_concept.png?nolink&500|}}
+{{ :stance_and_swing2.png?nolink&108|}}
 **Abstract:**
-Biomechanical models with different levels of complexity are of advantage to understand the underlying principles of legged locomotion. Following a minimalistic approach of gradually increasing model complexity based on Template & Anchor concept, in this paper, a spring-loaded inverted pendulum-based walking model is extended by a rigid trunk, hip muscles and reflex control, called nmF (neuromuscular force modulated compliant hip) model. Our control strategy includes leg force feedback to activate hip muscles (originated from the FMCH approach), and a discrete linear quadratic regulator for adapting muscle reflexes. The nmF model demonstrates human-like walking kinematic and dynamic features such as the virtual pendulum (VP) concept, inherited from the FMCH model. Moreover, the robustness against postural perturbations is two times higher in the nmF model compared to the FMCH model and even further increased in the adaptive nmF model. This is due to the intrinsic muscle dynamics and the tuning of the reflex gains. With this, we demonstrate, for the first time, the evolution of mechanical template models (e.g. VP concept) to a more physiological level (nmF model). This shows that the template model can be successfully used to design and control robust locomotor systems with more realistic system behaviours.
+Lower limb exoskeletons require the correct support magnitude and timing to achieve user assistance. This study evaluated whether the sign of the angular velocity of lower limb segments can be used to determine the timing of the stance and the swing phase during walking. We assumed that stance phase is characterized by a positive, swing phase by a negative angular velocity. Thus, the transitions can be used to also identify heel-strike and toe-off. Thirteen subjects without gait impairments walked on a treadmill at speeds between 0.5 and 2.1 m/s on level ground and inclinations between −10 and +10°. Kinematic and kinetic data was measured simultaneously from an optical motion capture system, force plates, and five inertial measurement units (IMUs). These recordings were used to compute the angular velocities of four lower limb segments: two biological (thigh, shank) and two virtual that were geometrical projections of the biological segments (virtual leg, virtual extended leg). We analyzed the reliability (two sign changes of the angular velocity per stride) and the accuracy (offset in timing between sign change and ground reaction force based timing) of the virtual and biological segments for detecting the gait phases stance and swing. The motion capture data revealed that virtual limb segments seem superior to the biological limb segments in the reliability of stance and swing detection. However, increased signal noise when using the IMUs required additional rule sets for reliable stance and swing detection. With IMUs, the biological shank segment had the least variability in accuracy. The IMU-based heel-strike events of the shank and both virtual segment were slightly early (3.3–4.8% of the gait cycle) compared to the ground reaction force-based timing. Toe-off event timing showed more variability (9.0% too early to 7.3% too late) between the segments and changed with walking speed. The results show that the detection of the heel-strike, and thus stance phase, based on IMU angular velocity is possible for different segments when additional rule sets are included. Further work is required to improve the timing accuracy for the toe-off detection (swing).
-**Keywords:** Template & Anchor, leg force feedback, posture control, reflex control, sensor-motor map.
+For further publications of the autohr 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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