Andre Seyfarth

• Professor in Sports Biomechanics
• Professor at Technical University of Darmstadt

This study addresses the vertical human–structure interaction (vHSI) and its effect on vertical ground reaction forces (vGRFs) as well as on gait adaptation in terms of cadence adjustment by analyzing the gait of individual subjects crossing an experimental pedestrian bridge. A comprehensive study was performed on 26 subjects to compare GRFs of two...

Adaptive motor control and seamless coordination of muscle actions in response to external perturbations are crucial to maintaining balance during bipedal locomotion. There is an ongoing debate about the specific roles of individual muscles and underlying neural control circuitry that humans employ to maintain balance in different perturbation scen...

Lower limb exoskeletons serve multiple purposes, like supporting and augmenting movement. Biomechanical models are practical tools to understand human movement, and motor control. This paper provides an overview of these models and a comprehensive review of the current applications of them in assistive device development. It also critically analyze...

This paper proposes a bio-inspired, simple, and easy-to-implement walking controller, termed Concerted Control , which leverages a shared common signal to coordinate movements across multiple joints without requiring predefined trajectories. The backbone of this controller is our previously developed Force Modulated Compliance (FMC) control concept...

Precise and portable ground reaction force (GRF) measurement is critical for advancing biomechanical gait analysis and enabling more effective control of robots and assistive devices. This study investigates vertical GRF estimation during walking using a soft, lightweight, and cost-effective 3D-printed ferroelectret insole. The insole design incorp...

Maintaining balance during human walking hinges on the exquisite orchestration of whole-body angular momentum (WBAM). This study delves into the regulation of WBAM during gait by examining balance strategies in response to upper-body moment perturbations in the frontal plane. A portable Angular Momentum Perturbator (AMP) was utilized in this work,...

Detecting human movement is crucial for the control of lower limb wearable robotics designed to assist daily activities or rehabilitation tasks. Sensorized insoles present a viable option for extracting control inputs, such as gait events and the corresponding phases, essential for regulating the magnitude and timing of assistance. Given their high...

Inclusive design does not stop at removing physical obstacles such as staircases. It also involves identifying architectural features that impose sensory burdens, such as repetitive visual patterns that are known to potentially cause dizziness or visual discomfort. In order to assess their influence on human gait and its stability, three repetitive...

Learning a locomotion controller for a musculoskeletal system is challenging due to over-actuation and high-dimensional action space. While many reinforcement learning methods attempt to address this issue, they often struggle to learn human-like gaits because of the complexity involved in engineering an effective reward function. In this paper, we...

In recent years, research on human-induced vibrations has developed several advanced modelling approaches aimed at achieving a more accurate description of human-structure interaction (HSI). The prevailing method involves using the load function from walking individuals on rigid ground as a starting point, considering the deviation when walking on...

Compliant leg function found during bouncy gaits in humans and animals can be considered a role model for designing and controlling bioinspired robots and assistive devices. The human musculoskeletal design and control differ from distal to proximal joints in the leg. The specific mechanical properties of different leg parts could simplify motor co...

Exploring the fundamental mechanisms of locomotion extends beyond mere simulation and modeling. It necessitates the utilization of physical test benches to validate hypotheses regarding real-world applications of locomotion. This study introduces cost-effective modular robotic platforms designed specifically for investigating the intricacies of loc...

Exploring the fundamental mechanisms of locomotion extends beyond mere simulation and modeling. It necessitates the utilization of physical test benches to validate hypotheses regarding real-world applications of locomotion. This study introduces cost-effective modular robotic platforms designed specifically for investigating the intricacies of loc...

Adaptive motor control and seamless coordination of muscle actions in response to external perturbations are crucial to maintaining balance during bipedal locomotion. There is an ongoing debate about the specific roles of individual muscles and underlying neural control circuitry that humans employ to maintain balance in different perturbation scen...

Current designs of structures often involve creative uses of materials and colours. While it is well known that patients with balance related disorders can experience negative effects through perceptual perturbations, the connection from these effects to physical changes still remains unclear. This paper therefore showcases the gait changes induced...

p>A comprehensive review of the applications of the biomechanical gait models in the development of lower-limb exoskeletons.</p

p>A comprehensive review of the applications of the biomechanical gait models in the development of lower-limb exoskeletons.</p

A more human-compatible design of exosuits provides new aspects in assisting people. This study presents a novel bioinspired method to design and control an exosuit to support human locomotion. We introduce a methodological design and development of the BATEX as an exosuit with compliant biarticular thigh actuators. By using series elastic actuat...

FULLTEXT (open access): Seyfarth, A., Hilgner, M. & Kühner-Stier, B. (2023). Collaborative learning environments - Learning with Tiny Articles as a participatory learning network. In M. Carmo (Ed.), Education Applications & Developments VIII. Advances in Education and Educational Trends Series (S. 121-128). inScience Press. https://insciencepress....

The lower limb morphology of biological locomotors is abundant in muscle-tendon units. Yet, not much is known about how these actuation units contribute to the output performance and energy economy of movements. In this work, we investigate the functionality of four of the important lower limb muscles - Vastus, Popliteus, Soleus, and Gastrocnemius...

The interaction between the motor control and the morphological design of the human leg is critical for generating efficient and robust locomotion. In this paper, we focus on exploring the effects of the serial and parallel elasticity on hopping with a two-segmented robotic leg called electric-pneumatic actuation (EPA)-Hopper. EPA-Hopper uses a hyb...

The identification of human-structure interaction (HSI) needs flexible ground conditions. A widely used method is the determination of ground reaction forces (GRF) by using portable force plates, with the main drawback of the plates being their predefined measurement zones that obstruct people from their natural gait during locomotion. The current...

"The current Corona crises demonstrates the challenge of a fruitful and trustful learning dynamics among people with largely varying backgrounds. The dynamics may easily lead to separating people into groups with attributed properties which finally impairs the learning process. In this study we aimed at designing a new teaching concept for first gr...

The dynamics of the human body can be described by the accelerations and masses of the different body parts (e.g., legs, arm, trunk). These body parts can exhibit specific coordination patterns with each other. In human walking, we found that the swing leg cooperates with the upper body and the stance leg in different ways (e.g., in-phase and out-o...

p>Especially lightweight and long-span footbridges are prone to vibrations and oscillations induced by users or environmental factors. While the interaction between construction, structure, stability and resulting vibrations have been investigated thoroughly in the past, research assessing user experience remains sparse. In this paper, we discuss...

p>Comfort and acceptance are vital to user experience and therefore one of the main challenges in footbridge design. Due to the community’s current thrive towards efficient lightweight footbridges, pedestrian induced vibrations come into focus. This implies the need for empirical investigations of user experience on vibrating footbridges. In this...

The highly dynamic hybrid nature of legged locomotion makes it a very challenging task to control. A proper control strategy, besides the ability to generate stable motions, should also possess generalization capabilities and adjustability to different conditions. In this regard, this work takes a step forward in promoting the concept of Force Modu...

In order to approach the performance of biological locomotion in legged robots, better integration between body design and control is required. In that respect, understanding the mechanics and control of human locomotion will help us build legged robots with comparable efficient performance. From another perspective, developing bioinspired robots c...

At the Cybathlon 2016 the performance of active and passive assistive devices for legged locomotion was compared. In the category of legged prostheses, surprisingly passive devices outperformed active ones regarding their performance in challenging tasks. Also the performance of active exoskeletons clearly demonstrated the still limited mobility pe...

This study aims to improve our understanding of gait initiation mechanisms and the lower-limb joint mechanical energy contributions. Healthy subjects were instructed to initiate gait on an instrumented track to reach three self-selected target velocities: slow, normal and fast. Lower-limb joint kinematics and kinetics of the first five strides were...

Biological actuators can be recruited to match the requirements of different motor tasks and conditions. In this chapter, we discuss how redundancies in motor control could be resolved following a template-based approach. We explore the recruitment of sensory pathways using the concepts of graphical sensor motor maps and locomotor subfunctions.

Summarizing and discussing the contents of the previous chapters, we provide biological, engineering, bioinspiration, and application considerations of bioinspired actuators for robotics.

Achieving efficient and human-like hopping motions with consistent consecutive patterns requires proper mechanical design and control. In this regard, we introduce a new bioinspired design and control approach comprised of a hybrid actuation system and force-based compliance control. Combining an electric motor with a pneumatic artificial muscle ma...

Um den Menschen bedarfsgerecht und ergonomisch unterstützen zu können, müssen Assistenzsysteme die Bewegungen und Bewegungsabsichten des Nutzers frühzeitig erkennen. Die Individualität der menschlichen Bewegung ist dabei eine besondere Herausforderung. Dieser Beitrag zeigt, dass maschinelles Lernen geeignet ist, um aus den Daten ausgewählter, am Kö...

Robotic limb design struggles to combine energy efficiency with human-like levels of movement versatility. High efficiency and a range of angles and torques are characteristics of human hopping at different frequencies. Humans use muscles in combination with tendons to achieve the required joint actuation. Therefore, we consider whether appropriate...

This book discusses biologically inspired robotic actuators designed to offer improved robot performance and approaching human-like efficiency and versatility. It assesses biological actuation and control in the human motor system, presents a range of technical actuation approaches, and discusses potential applications in wearable robots, i.e., pow...

This article presents a novel neuromechanical force-based control strategy called FMCA (force modulated compliant ankle), to control a powered prosthetic foot. FMCA modulates the torque, based on sensory feedback, similar to neuromuscular control approaches. Instead of using a muscle reflex-based approach, FMCA directly exploits the vertical ground...

Bipedal locomotion in uncertain environments is a challenging control problem. In order to reduce the effect of imprecise and noisy measurements, performance enhancement and energy consumption reduction, many researchers employ compliant elements in the robot structure, parallel to the control system. However, there is no systematic methodology for...

Redundancy facilitates some of the most remarkable capabilities of humans, and is therefore omni-present in our physiology. The relationship between redundancy in robotics and biology is investigated in detail on the Series Elastic Dual-Motor Actuator (SEDMA), an actuator inspired by the kinematic redundancy exhibited by myofibrils. The actuator co...

There is a long history demonstrating humans' tendency to create artificial copies of living creatures. For moving machines called robots, actuators play a key role in developing human-like movements. Among different types of actuation, PAMs (pneumatic artificial muscles) are known as the most similar ones to biological muscles. In addition to simi...

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 biarti...

It has been shown that human-like hopping can be achieved by muscle reflex control in neuromechanical simulations. However, it is unclear if this concept is applicable and feasible for controlling a real robot. This paper presents a low-cost two-segmented robotic leg design and demonstrates the feasibility and the benefits of the bio-inspired neuro...

The original article contains an error in Fig 3f whereby data is erroneously extrapolated beyond 80 years of age; this also affects statements made elsewhere in the article.

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 whi...

In this paper we present the novel teaching project ANSYMB which we introduced during the last years at Technische Universität Darmstadt. In ANSYMB, students learn to analyse and synthesize human movements using research techniques used in biomechanics, computer sciences and engineering. Here, we explain key concepts and illustrate some of the outc...

The chapter focuses on three areas based on realization of neural control for gait assistance. The neural control could be identified by applying neuronal signals to control powered prostheses. For this, the first section summarizes the variety of possible control input signals for powered prostheses and exoskeletons with a focus on electromyograpy...

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 incre...

1. State of the art and preliminary work Legged robots comprise passive parts (e.g., segments, joints, and connections) which are moved in a coordinated manner by actuators. In this project, we will design a new hybrid ac-tuator to outperform existing actuators in efficiency and robustness over the operational region required for human-like gaits....

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 si...

In human locomotion, the complex structure of body is controlled such that conceptual models can describe the significant features. This suggests that the interplay of the complex control and musculoskeletal systems projects into a low dimensional space to perform different movements. Such simplification can involve splitting the task into differen...

In this paper, we present a novel template model- based control approach for control of ankle prosthesis. This method which is called FMCA (force modulated compliant ankle) employs ground reaction force to modulate ankle joint impedance. Inspired by our previous studies and also findings in human gaits, we know that leg force could play an importan...

In this paper, we present a novel template model- based control approach for control of ankle prosthesis. This method which is called FMCA (force modulated compliant ankle) employs ground reaction force to modulate ankle joint impedance. Inspired by our previous studies and also findings in human gaits, we know that leg force could play an importan...

Benefiting from serial compliance in series elastic actuators (SEA) can be considered as a breakthrough in robotics. Recently, applying the parallel compliance in robot designs is growing based on its advantages such as reduction in consumed torques. In this paper, we aim at employing parallel compliance to increase walking robustness of bipedal ro...

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 pendulumbased walking model is extended by a rigid trunk, hip m...

In human locomotion, the complex structure of the human body is controlled such that conceptual models (e.g., the Spring-Loaded-Inverted-Pendulum model) can describe the significant features. This suggests that the interplay of the complex control and musculoskeletal systems projects into a low dimensional space to perform different movements. Such...

Background: Physical and functional losses due to aging and diseases decrease human mobility, independence, and quality of life. This study is aimed at summarizing and quantifying these losses in order to motivate solutions to overcome them with a special focus on the possibilities by using lower limb exoskeletons. Methods: A narrative literature...

Human locomotion is a complex movement task, which can be divided into a set of locomotor subfunctions. These subfunction comprise stance leg function, swing leg function and balance. Each of these locomotor subfunctions requires a specific control of individual muscles in the human body. We propose a novel method based on sensor-motor-maps to iden...

Our daily activities involve different types of locomotion, including walking and running. In this paper we present a series of biomechanical models to describe such locomotor activities with a set only a few characteristic parameters. With this we aim at providing an introduction to the modelling of human locomotion which is equally appropriate fo...

This paper proposes a methodology to reconstruct the vertical GRFs from the registered body motion that is reasonably robust against measurement noise. The vertical GRFs are reconstructed from the experimentally identified time-variant pacing rate and a generalised single-step load model available in the literature. The proposed methodology only re...

Template models of legged locomotion are powerful tools for gait analysis, but can also inspire robot design and control. In this paper, a spring-loaded inverted pendulum (SLIP) model is employed to control vertical hopping of a 2-segmented legged robot. Feed-forward and bio-inspired virtual model control using the SLIP model are compared. In the l...

Perturbations are used to study and identify mechanisms of human motor control. This study introduces a concept for a movement manipulator prototype to explore human response and recovery strategies following temporary perturbations at the local joint level. We utilized a soft humanmachine interface in combination with a tethered actuation unit to...

Assistive devices can be considered as one of the main applications of legged locomotion research in daily life. In order to develop an efficient and comfortable prosthesis or exoskeleton, biomechanical studies on human locomotion are very useful. In this paper, the applicability of the FMCH (force modulated compliant hip) model is investigated for...

Simplifying legged locomotion through abstraction and splitting it to subproblems (locomotor subfunctions) pioneered by Raibert hopper is addressed in this paper. Using neuromechanical models, we focus on coordination between stance and balance locomotor subfunctions in a vertical hopping task. Stance and balance control relate to the axial and per...

To account for the human-structure interaction during walking on flexible structures, a pedestrian is typically represented by an equivalent single degree of freedom (SDOF) system moving over the structure at a constant speed together with an external force. The latter corresponds to the force exerted by a pedestrian when walking on a rigid structu...

In human and animal motor control several sensory organs contribute to a network of sensory pathways modulating the motion depending on the task and the phase of execution to generate daily motor tasks such as locomotion. To better understand the individual and joint contribution of reflex pathways in locomotor tasks, we developed a neuromuscular m...

As the conclusion of the book, state-of-the-art research regarding legged locomotion and the application to daily activities are presented in this chapter. By comparing engineered legged systems with animals we address how far we are from nature. The recent technologies on assistive devices demonstrate the applicability of the scientific methods to...

Legged locomotion is a complex hybrid, nonlinear and highly dynamic problem. Animals have solved this complex problem as they are able to generate energy efficient and robust locomotion resulted from million years of evolution. However, different aspects of locomotion in biological legged systems such as mechanical design, actuation and control are...

This chapter provides an overview of simple conceptual models of locomotion at the scale of whole body movements. First, conceptual models of locomotion are introduced along with a few key empirical observations that support the construction of simple conceptual models. Next, a theoretical perspective is offered based on "templates and anchors" the...

Bioinspired Legged Locomotion: Models, Concepts, Control and Applications explores the universe of legged robots, bringing in perspectives from engineering, biology, motion science, and medicine to provide a comprehensive overview of the field. With comprehensive coverage, each chapter brings outlines, and an abstract, introduction, new development...

A better understanding of how actuator design supports locomotor function may help develop novel and more functional powered assistive devices or robotic legged systems. Legged robots comprise passive parts (e.g., segments, joints and connections) which are moved in a coordinated manner by actuators. In this study, we propose a novel concept of a h...

Neuromuscular control models describe human locomotion by combining kinematic chain representations of the human skeleton with models of muscle-tendon actuators and control architectures mimicking neural circuits. The models have originally been developed to better understand human motor control. However, over the past two decades, they have reache...

p>This contribution presents selected results of the numerical and experimental investigations into the effect of human-structure interaction, performed within a joint project between the Institute of Structural Mechanics and Design and the Institute of Sport Science of the TU Darmstadt (Germany). The project on the one side analyses structural res...

A primary goal of comparative biomechanics is to understand the fundamental physics of locomotion within an evolutionary context. Such an understanding of legged locomotion results in a transition from copying nature to borrowing strategies for interacting with the physical world regarding design and control of bio-inspired legged robots or robotic...

Passive prosthetic feet are not able to provide non-amputee kinematics and kinetics for the ankle joint. Persons with amputations show reduced interlimb symmetry, slower walking speeds, and increased walking effort. To improve ankle range of motion and push off, various powered prosthetic feet were introduced. This feasibility study analyzed if pre...