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--- start [2019/09/20 10:15]
Guoping Zhao [Parallel compliance design for increasing robustness and efficiency in legged locomotion-proof of concept]
+++ start [2020/02/11 08:56]
Martin Grimmer
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 ====== News ======
-  * {{::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]]
+  * {{::ansymb_logo_i.png?90 | Teaching course ANSYMB II}} **Running this winter term!** [[http://www.ansymb.tu-darmstadt.de/|   Analysis and Synthesis of Human Movements]]
-====== Pick of the Month  ======
-==== Bio-Inspired Balance Control Assistance Can Reduce Metabolic Energy Consumption in Human Walking ====
+====== Latest Publications ======
-A new control method, which is inspired by a human posture control concept, is proposed and tested in this research. It can not only facilitate the human gait, but also reduce the exoskeleton power consumption. This study is presented in a recently published paper by Zhao et al. in [[https://ieeexplore.ieee.org/document/8794599|IEEE Transactions on Neural Systems and Rehabilitation Engineering]].
+==== Human Lower Limb Joint Biomechanics in Daily Life Activities: A Literature Based Requirement Analysis for Anthropomorphic Robot Design  ====
-{{ :control_scheme_zhao.png?nolink&500|}}
+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.
-The amount of research on developing exoskeletons for human gait assistance has been growing in the recent years. However, the control design of exoskeletons for assisting human walking remains unclear. This paper presents a novel bio-inspired reflex-based control for assisting human walking. In this approach, the leg force is used as a feedback signal to adjust hip compliance. The effects of modulating hip compliance on walking gait is investigated through joint kinematics, leg muscle activations and overall metabolic costs for eight healthy young subjects. Reduction in the average metabolic cost and muscle activation are achieved with fixed hip compliance. Compared to the fixed hip compliance, improved assistance as reflected in more consistent reduction in muscle activities and more natural kinematic behaviour are obtained using the leg force feedback. Furthermore, smoother motor torques and less peak power are two additional advantages obtained by compliance modulation. The results show that the proposed control method which is inspired by human posture control can not only facilitate the human gait, but also reduce the exoskeleton power consumption. This demonstrates that the proposed bio-inspired controller allows a synergistic interaction between human and robot.
+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]]
+\\
+==== Review of balance recovery in response to external perturbations during daily activities  ====
-For further publications of the author please check: [[https://www.researchgate.net/profile/Guoping_Zhao2|ResearchGate]],
+Balance related responses to perturbations were investigated in one of our latest studies by Dr. Dario Tokur, Dr. [[lab_members:lab_members_martingrimmer|Martin Grimmer]] and Prof. Andre Seyfarth. The work was recently published in [[https://doi.org/10.1016/j.humov.2019.102546|Human Movement Science]].
-[[https://orcid.org/0000-0002-1908-5388|ORCID]] or [[https://loop.frontiersin.org/people/378544/overview|LOOP]]
+{{ ::perturbation.png?300|}}
+**Abstract:**
+Balance is an essential capability to ensure upright standing and locomotion. Various external perturbations challenge our balance in daily life and increase the risk for falling and associated injury. Researchers try to identify the human mechanisms to maintain balance by intentional perturbations. The objectives of this work were to point out which areas of perturbation based research are well covered and not well covered and to extract which coping mechanisms humans use to respond to external perturbations. A literature review was performed to analyze mechanisms in response to external perturbations such as pushes to the body or ground level changes during standing, walking, running and hopping. To get a well-structured overview on the two dimensions, the perturbation type and the task, the Perturbation Matrix (PMA) was designed. We found that multiple studies exist for the tasks walking and standing, while hopping and running are covered less. However, all tasks still offer opportunities for both in-depth and fundamental research. Regarding the recovery mechanisms we found that humans can recover from various types of perturbations with versatile mechanisms using combinations of trunk, as well as upper and lower limb movements. The recovery movements will adapt depending on the perturbation intensity, direction and timing. Changes in joint kinetics, joint kinematics and muscle activity were identified on the joint level and leg stiffness and leg length on the global leg level. We believe that the insights from the extracted mechanisms may be applied to the hardware and control of robotic limbs or lower limb exoskeletons to improve the balance and robustness during standing or locomotion.
+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]]
 \\
+==== Biomechanical effects of passive hip springs during walking  ====
+The effects of passive springs at the hip were investigated in a collaboration project of Florian Haufe, Peter Wolf and Robert Riener from the [[https://sms.hest.ethz.ch/|Sensory-Motor Systems Lab]] from ETH Zurich and [[lab_members:lab_members_martingrimmer|Martin Grimmer]] from the Lauflabor. The work was recently published in the [[https://www.sciencedirect.com/science/article/abs/pii/S0021929019306797|Journal of Biomechanics]].
+{{ ::passive_hip_spring.jpg?400|}}
+**Abstract:**
+Passive spring-like structures can store and return energy during cyclic movements and thereby reduce the energetic cost of locomotion. That makes them important components of the human body and wearable assistive devices alike. This study investigates how springs placed anteriorly across the hip joint affect leg joint angles and powers, and leg muscle activities during level walking at 0.5 to 2.1 m/s.
+We hypothesized that the anterior hip springs (I) load hip extension, (II) support hip flexion and (III) affect ankle muscle activity and dynamics during walking. Effects at the ankle were expected because hip and ankle redistribute segmental power in concert to achieve forward progression.
+We observed that the participants’ contribution to hip power did not increase during hip extension as the spring stored energy. Simultaneously, the activities of plantarflexor muscles that modulate energy storage in the Achilles tendon were reduced by 28% (gastrocnemius medialis) and 9% (soleus). As the spring returned energy with the onset of hip flexion, the participants’ contribution to hip power was reduced by as much as 23%. Soleus activity before push-off increased by up to 9%.
+Instead of loading hip extension, anterior hip springs seem to store and return parts of the energy normally exchanged with the Achilles tendon. Thereby, the springs support hip flexion but may reduce elastic energy storage in and hence recoil from the Achilles tendon. This interaction should be considered during the design and simulation of wearable assistive devices as it might – depending on user characteristics – enhance or diminish their overall functionality.
+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]]
+\\
+===== Biarticular muscles are most responsive to upper-body pitch perturbations in human standing =====
+Our latest publication features the results of [[http://lauflabor.ifs-tud.de/doku.php?id=lab_members:lab_members_christian_schumacher|Christian]]'s lab visit in the [[http://dbl.tudelft.nl/|Delft Biorobotics Lab]]. The study investigates important muscle groups to maintain an upright body posture when being perturbed. For this purpose, he used a novel type of balance perturbation, a control moment gyroscope (see Figure) that exerts a torque on the subject's upper body. Find more information in the published paper: [[https://www.nature.com/articles/s41598-019-50995-3|Link to Scientific Reports]].
+{{ :gyro.jpg?nolink&600|[[https://www.nature.com/articles/s41598-019-50995-3|Link to Scientific Reports]] }}
+**Abstract:**
+Balancing the upper body is pivotal for upright and efficient gait. While models have identified potentially useful characteristics of biarticular thigh muscles for postural control of the upper body, experimental evidence for their specific role is lacking. Based on theoretical findings, we hypothesised that biarticular muscle activity would increase strongly in response to upper-body perturbations. To test this hypothesis, we used a novel Angular Momentum Perturbator (AMP) that, in contrast to existing methods, perturbs the upper-body posture with only minimal effect on Centre of Mass (CoM) excursions. The impulse-like AMP torques applied to the trunk of subjects resulted in upper-body pitch deflections of up to 17° with only small CoM excursions below 2 cm. Biarticular thigh muscles (biceps femoris long head and rectus femoris) showed the strongest increase in muscular activity (mid- and long-latency reflexes, starting 100 ms after perturbation onset) of all eight measured leg muscles which highlights the importance of biarticular muscles for restoring upper-body balance. These insights could be used for improving technological aids like rehabilitation or assistive devices, and the effectiveness of physical training for fall prevention e.g. for elderly people.
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