Maziar Ahmad Sharbafi

Maziar Ahmad Sharbafi
University of Tehran | UT · School of Electrical and Computer Engineering

Ph.D.

About

92
Publications
34,615
Reads
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788
Citations
Additional affiliations
January 2016 - present
University of Tehran
Position
  • Professor (Assistant)
September 2013 - present
Technische Universität Darmstadt
Position
  • PostDoc Position
August 2011 - September 2013
Technische Universität Darmstadt
Position
  • Researcher
Education
September 2007 - September 2013
University of Tehran
Field of study
  • Electrical Engineering/ Control
September 2003 - February 2006
University of Tehran
Field of study
  • Electrical Engineering/ Control
September 1999 - September 2003
Sharif University of Technology
Field of study
  • Electrical Engineering/ Control

Publications

Publications (92)
Article
Passive prosthetic feet struggle to reproduce the human biological ankle range of motion and push-off. We propose the Hybrid-Hydraulic Ankle Prosthesis (H2AP), a prosthetic foot that provides a greater range of motion and push-off support compared to regular carbon feet. This novel prosthesis comprises a carbon foot and a hydraulic unit that includ...
Article
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...
Article
Full-text available
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...
Article
Balance control is one of the crucial challenges in bipedal locomotion. Humans need to maintain their trunk upright while the body behaves like an inverted pendulum which is inherently unstable. Instead, the virtual pivot point (VPP) concept introduced a new virtual pendulum model to the human balance control paradigm by analyzing the ground reacti...
Chapter
Full-text available
Nowadays, enhancing the physical abilities of able-bodied humans attracted the researchers’ attention besides the development of assistive devices for people with mobility disorders. As a result, the interest in designing of cheap and soft wearable exoskeletons called exosuits is distinctly growing. Careful investigation of the biological musculosk...
Article
The invention of soft wearable assistive devices, known as exosuits, introduced a new aspect in assisting unimpaired subjects. In this study, we designed and developed an exosuit with compliant biarticular thigh actuators called BATEX. Unlike the conventional method of using rigid actuators in exosuits, the BATEX is made of serial elastic actuators...
Chapter
Summarizing and discussing the contents of the previous chapters, we provide biological, engineering, bioinspiration, and application considerations of bioinspired actuators for robotics.
Chapter
Compared to biological muscles, current technical actuators are limited in their performance and versatility to realize human-like locomotion. In order to overcome the actuator limitations for locomotion, we introduce the hybrid EPA actuator as a combination of electric and pneumatic actuators in this chapter. As a new variable impedance actuator,...
Article
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...
Patent
Full-text available
73) Assignee : Tarbiat Modares University , Tehran (IR) (21) Appl. No .: 17 / 092,356 A passive ankle-foot prosthesis to replicate a human foot. The passive ankle-foot prosthesis includes a foot part , an ankle frame , a yoke , and a spring. The ankle frame is attached fixedly to a second end of the foot part. The yoke is configured to be attached...
Book
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...
Article
Full-text available
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...
Article
Full-text available
Specifications of actuators when interacting with biological systems such as the human body are entirely different from those used in industrial machines or robots. One important instance of such applications is assistive devices and prostheses. Among various approaches in designing prostheses, recently, semi-active systems attracted the interest o...
Conference Paper
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...
Preprint
Full-text available
By invention of soft wearable assistive devices, known as exosuits, a new aspect in assisting unimpaired subjects is introduced. In this study, we designed and developed an exosuit with compliant biarticular thigh actuators, called BAExo. Unlike common method of using rigid actuators in exosuits, the BAExo is made of serial elastic actuators (SEA)...
Article
Full-text available
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...
Article
Full-text available
Nowadays, the focus on the development of assistive devices just for people with mobility disorders has shifted towards enhancing physical abilities of able-bodied humans. As a result, the interest in the design of cheap and soft wearable exoskeletons (called exosuits) is distinctly growing. In this paper, a passive lower limb exosuit with two biar...
Chapter
Full-text available
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...
Preprint
Full-text available
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....
Article
Full-text available
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...
Conference Paper
Full-text available
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...
Conference Paper
Full-text available
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...
Conference Paper
Full-text available
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...
Article
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...
Article
Full-text available
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...
Article
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...
Chapter
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...
Article
Full-text available
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...
Article
Full-text available
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...
Conference Paper
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...
Article
Full-text available
Bipedal walking with hybrid and nonlinear dynamics is a complex control problem. In this paper, a new model of bipedal walker with compliant legs and curved feet is developed and controlled using hybrid zero dynamics (HZD) controller. We analyze the effect of foot design in generating stable gaits characteristics regarding robustness and efficiency...
Chapter
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...
Chapter
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...
Chapter
Full-text available
This chapter discusses how biologically inspired principles and mechanisms can be transferred in the engineering domain with the purpose of designing legged robots capable of reproducing animal locomotion behaviors. A bioinspired design approach is described, which relies on quantifying the basic principles underlying a desired locomotion behavior...
Chapter
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...
Book
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...
Article
Full-text available
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...
Article
Full-text available
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...
Conference Paper
Full-text available
We present a novel control approach for assistive lower-extremity exoskeletons. In particular, we implement a virtual pivot point (VPP) template model inspired leg force feedback based controller on a lower-extremity powered exoskeleton (LOPES II) and demonstrate that it can effectively assist humans during walking. It has been shown that the VPP t...
Article
Template models, which are utilized to demonstrate general aspects in human locomotion, mostly investigate stance leg operation. The goal of this paper is presenting a new conceptual walking model benefiting from swing leg dynamics. Considering a double pendulum equipped with combinations of biarticular springs for the swing leg beside spring-mass...
Poster
Full-text available
The effects of muscle sensory information (muscle’s length, velocity and force) on postural balance were analyzed in this research.
Article
Inspired from template models explaining biological locomotory systems and Raibert's pioneering legged robots, locomotion can be realized by basic sub-functions: elastic axial leg function, leg swinging and balancing. Combinations of these three can generate different gaits with diverse properties. In this paper we investigate how locomotion sub-fu...
Conference Paper
Full-text available
Experiments on human subjects, data analyses and modeling can help the engineers design and develop high performance humanoid robots and assistive devices. In an abstract level bipedal locomotion can be considered as a combination of three sub-functions: stance, swing and posture control. In this paper, we focus on swing leg adjustment searching fo...
Article
Full-text available
Bioinspired legged locomotion comprises different aspects, such as (i) benefiting from reduced complexity control approaches as observed in humans/animals, (ii) combining embodiment with the controllers and (iii) reflecting neural control mechanisms. One of the most important lessons learned from nature is the significant role of compliance in simp...
Conference Paper
In human hopping in place, the axial leg function is representable by a spring mass model. This description can be utilized to control robot hopping. In this paper, the SLIP (spring loaded inverted pendulum) model is employed as a template for the control of MARCO Hopper II, a robot with a two-segmented leg. Using VMC (virtual model control) a spri...
Conference Paper
Full-text available
Spring loaded inverted pendulum (SLIP) model used simple spring mass mechanism to explain leg function and ground reaction force in legged locomotion. Balancing the upper body can be addressed by addition of a rigid trunk to this template model. The resulting model is not conservative and needs hip torque to keep the trunk upright during locomotion...
Conference Paper
Full-text available
Walking with 5-link model has been achieved by HZD (Hybrid Zero Dynamics) controller based on virtual constraints. These holonomic constraints are obtained by optimizing a set of virtual relations (e.g., Beziér polynomial) between system states which mostly do not have physical interpretations. In this paper, the virtual constraints are designed us...
Conference Paper
Swing-leg retraction, the backward rotation of the swing leg just prior to ground contact, is observed in human locomotion. While several advantages of swing-leg retraction, like gait stability and perturbation rejection, are shown by conceptual models, there is currently very little experimental data on swing-leg retraction in human motion. In thi...
Conference Paper
Full-text available
Swing leg adjustment, repulsive leg function and balance are key elements in the control of bipedal locomotion. In simple gait models like spring-loaded inverted pendulum (SLIP), swing leg control can be applied to achieve stable running. The aim of this study is to investigate the ability of pendulum like swing leg motion for stabilizing running a...
Conference Paper
Full-text available
Bipedal locomotion can be divided into primitive tasks, namely repulsive leg behavior (bouncing against gravity), leg swing (protraction and retraction) and body alignment (balancing against gravity). In the bipedal spring-mass model for walking and running, the repulsive leg function is described by a linear prismatic spring. This paper adopts two...
Conference Paper
Full-text available
Balancing the upper body as one of the main features in human locomotion is achieved by actuation of the compliant hip joints. Using leg force feedback to adjust the hip spring is presented as a new postural control technique. This method results in stable and robust running with the conceptual SLIP model which is extended by addition of a rigid tr...
Conference Paper
Full-text available
Swing-leg retraction, the backward rotation of the swing leg just prior to ground contact, is observed in human locomotion. While several advantages of swing- leg retraction, like gait stability and perturbation rejection, are shown by con- ceptual models, there is currently very little experimental data on swing-leg retraction in human motion. In...
Article
Full-text available
There are three challenges in finding robot location and environment map which are accuracy, robustness and computational cost. Some simultaneous localisation and mapping (SLAM) methods work perfectly with ideal environment without uncertainties, noise and disturbances; however, in the real world, the performance considerably decreases. Designing a...
Conference Paper
Full-text available
Bouncing, balancing and swinging the leg forward can be considered as three basic control tasks for bipedal locomotion. Defining the trunk by an unstable inverted pendulum, balancing as being translated to trunk stabilization is the main focus of this paper. The control strategy is to generate a hip torque to have upright trunk to achieve robust ho...
Article
Full-text available
A new control approach to achieve robust hopping against perturbations in the sagittal plane is presented in this paper. In perturbed hopping, vertical body alignment has a significant role for stability. Our approach is based on the virtual pendulum concept, recently proposed, based on experimental findings in human and animal locomotion. In this...