Nikos G Tsagarakis

Nikos G Tsagarakis
Istituto Italiano di Tecnologia | IIT · Department of Advanced Robotics

DEEng, MSc, PhD

About

528
Publications
250,412
Reads
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14,904
Citations
Citations since 2017
222 Research Items
9812 Citations
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201720182019202020212022202305001,0001,500
201720182019202020212022202305001,0001,500
Additional affiliations
February 2007 - January 2016
Istituto Italiano di Tecnologia
Position
  • Tenured Scientist, Head of Humanid and Human Centered Mechatronics
February 2007 - present
Istituto Italiano di Tecnologia (IIT)
Position
  • Senior Scientist, Head of Humanoid and Human Centered Mechatronics

Publications

Publications (528)
Preprint
Full-text available
This work presents the computational design and validation of the Multi-Arm Relocatable Manipulator (MARM), a three-limb robot for space applications, with particular reference to the MIRROR (i.e., the Multi-arm Installation Robot for Readying ORUs and Reflectors) use-case scenario as proposed by the European Space Agency. A holistic computational...
Article
Orientation regulation permits an autonomous controller to regulate the operators' orientation commands automatically. Although kinds of orientation regulation strategies have been proposed for various purposes, few works have focused on the partial orientation regulation (POR), which requires an autonomous controller to prevent the unreachable rot...
Data
This is the attached video for our paper with the title "A Haptic Shared Autonomy with Partial Orientation Regulation for DoF Deficiency in Remote Side", which has been accpeted by IEEE Transactions on Haptics.
Conference Paper
Wheeled-legged robots have the potential to navigate in cluttered and irregular scenarios by altering the locomotion modes to adapt to the terrain challenges and effectively reach targeted locations in unstructured spaces. To achieve this functionality, a hybrid locomotion planner is necessary. In this work we present a search-based planner, which...
Conference Paper
Full-text available
Online motion re-planning is an important feature for introducing robots into unstructured environments where the close presence of humans at any time can challenge the operation of the robot from the human safety perspective. This work introduces a novel re-planning framework for robotic manipulators operating in dynamic environments where the int...
Conference Paper
This paper presents a simplified model-based trajectory optimization (TO) formulation for motion planning on quadruped mobile manipulators that carry heavy payload of known mass. The proposed payload-aware formulation simultaneously plans locomotion, payload manipulation and considers both robot and payload model dynamics while remaining computatio...
Conference Paper
Full-text available
The machine tending in a productive plant typically requires the transport of material from a storage area to a productive area. The plant logistics phase is a part of the production process that is often performed manually, due to the technological challenges related to the manipulation of objects in constrained environments, such as the shelf of...
Conference Paper
Full-text available
The teleoperation of mobile manipulators may pose significant challenges, demanding complex interfaces and causing a substantial burden to the human operator due to the need to switch continuously from the manipulation of the arm to the control of the mobile platform. Hence, several works have considered to exploit shared control techniques to over...
Conference Paper
Full-text available
Recent years have shown a growing demand toward automation in the industry and other contexts. To follow this trend, the research has to face some challenges to exploit the capabilities of complex robotic systems. Heavy redundant platforms, like dual arm manipulators, mobile robots, and legged systems, can help in accomplishing always more difficul...
Article
Full-text available
This paper presents Horizon, an open-source framework for trajectory optimization tailored to robotic systems that implements a set of tools to simplify the process of dynamic motion generation. Its user-friendly Python-based API allows designing the most complex robot motions using a simple and intuitive syntax. At the same time, the modular struc...
Article
This Closure exposes the technical inconsistencies, erroneous comments, and misconceptions contained in the Discussion Article coded JMR-20-1032 [1]. The majority of incorrect comments relating to stability is not based on mathematical rigour and equations, but on reproduction of more generic statements made in some textbooks published in the early...
Conference Paper
Full-text available
Wheeled-legged robots have the potential to navigate in cluttered and irregular scenarios by altering the locomotion modes to adapt to the terrain challenges and effectively reach targeted locations in unstructured spaces. To achieve this functionality, a hybrid locomotion planner is necessary. In this work we present a search-based planner, which...
Article
Full-text available
The Incomplete Orientation Constraint (IOC), which does not require a controlled motion constrained by all three spatial directions, exists widely in a lot of robotic tasks. However, the IOC remains a challenge for existing methods, due to the nonlinear structure of the rotation group SO(3). Moreover, the IOCs are time varying in the trajectory tra...
Preprint
Full-text available
For legged robots to perform agile, highly dynamic and contact-rich motions, whole-body trajectories computation of under-actuated complex systems subject to non-linear dynamics is required. In this work, we present hands-on applications of Horizon, a novel open-source framework for trajectory optimization tailored to robotic systems, that provides...
Preprint
Full-text available
The deployment of robots within realistic environments requires the capability to plan and refine the loco-manipulation trajectories on the fly to avoid unexpected interactions with a dynamic environment. This extended abstract provides a pipeline to offline plan a configuration space global trajectory based on a randomized strategy, and to online...
Article
The development of new materials/actuators in robotics leads to the rapid growth of new types of robots, including soft/continuum robots, reconfigurable robots, exoskeleton robots, haptic master devices, and so on. When designing a new robot, orientability is an important performance index to evaluate its dexterity. However, a theoretical investiga...
Article
Full-text available
Teleoperation permits to control robots from a safe distance while performing tasks in a remote environment. Kinematic differences between the input device and the remotely controlled manipulator or the existence of redundancy in the remote robot may pose challenges in moving intuitively the remote robot as desired by the human operator. Motivated...
Article
Full-text available
Legged and wheeled locomotion are two standard methods used by robots to perform navigation. Combining them to create a hybrid legged-wheeled locomotion results in increased speed, agility, and reconfigurability for the robot, allowing it to traverse a multitude of environments. The CENTAURO robot has these advantages, but they are accompanied by a...
Conference Paper
Full-text available
— In the past few years, several robotic end-effectors based on diverse kinematics and actuation principles have been developed to provide grasping and manipulation functionalities. To ease the control and application of these wide-ranging end-effectors, the development of effective reusable tools that can facilitate the end-effector motion plannin...
Article
Full-text available
In this work, we introduce the principle, design and mechatronics of Exo-Muscle, a novel assistive device for the knee joint. Different from the existing systems based on rigid exoskeleton structures or soft-tendon driven approaches, the proposed device leverages a new semi-rigid principle that explores the benefits of both rigid and soft systems....
Article
Full-text available
Most of the locomotion and contact planners for multi-limbed robots rely on a reduction of the search space to improve the performance of their algorithm. Posture generation plays a fundamental role in these types of planners providing a collision-free, statically stable whole-body posture, projected onto the planned contacts. However, posture gene...
Article
Full-text available
This paper proposes a Domain Specific Language to describe in a synthetic and comprehensive way, complex control problems for robotic systems. The proposed language, named Math of Tasks, abstracts from the mathematical description of the problem, which heavily depends on the particular algorithm chosen to solve it, relying on a set of operators and...
Article
Full-text available
This paper presents a novel omnidirectional walking pattern generator for bipedal locomotion combining two structurally different approaches based on the virtual constraints and the preview control theories to generate a flexible gait that can be modified on-line. The proposed strategy synchronizes the displacement of the robot along the two planes...
Conference Paper
Envisioning the employment of rope-assisted humanoid robots to reduce human intervention for operations in the heights, this preliminary work addresses the modeling and motion planning problems for a rope-assisted bipedal robot. The mathematical features of this system outnumber the ones of typical humanoid robots, including: under-actuation of th...
Article
Full-text available
The workspace limit to smoothly map unreachable motions sensed in the leader side to the reachable workspace of the follower robot is fundamental for teleoperation systems. Although numerous workspace determination methods have been studied, the workspace limit approach still remains challenging. The main difficulty is that the computation of the m...
Data
This video presents 5 tests for comparison: 1. The proposed SDF-based method; 2. A defective version of the proposed method without interpolation; 3. Box-Limits; 4. Bigger-Box-Limits; 5. No Limits. The 2nd test can avoid the unreachable inputs. But the discontinuity problem arises since the interpolation method is disenabled. The 3rd test gives up...
Chapter
Full-text available
The widespread use of robotics in new application domains outside the industrial workplace settings requires robotic systems which demonstrate functionalities far beyond that of classical industrial robotic machines. The implementation of these capabilities inevitably increases the complexity of the robotic hardware, control a and software componen...
Preprint
Full-text available
The kinematic features of a centaur-type humanoid platform, combined with a powerful actuation, enable the experimentation of a variety of agile and dynamic motions. However, the higher number of degrees-of-freedom and the increased weight of the system, compared to the bipedal and quadrupedal counterparts, pose significant research challenges in t...
Preprint
Full-text available
With the increasing complexity of teleopera-tion tasks, various teleoperation architectures, including the Single-Master/Single-Slave (SMSS), Multiple-Master/Multiple-Slave (MMMS), Single-Master/Multiple-Slave (SMMS), and Multiple-Master/Single-Slave (MMSS) systems, are emerging. Although numerous works have focused on the control strategies in tel...
Article
Full-text available
In this work we investigate and validate two methods that can extend the explosive motion capabilities of series elastic actuated robots during standing jumps. First, field weakening control is exploited on multiple joints of a monoped to boost their peak velocities. However, field weakening operation reduces actuation torque capacity at those velo...
Article
Full-text available
In the context of legged robotics, many criteria based on the control of the Center of Mass (CoM) have been developed to ensure stable and safe robot locomotion. Defining a whole-body framework with the control of the CoM requires a planning strategy, often based on a specific type of gait and reliable state-estimation. In a whole-body control appr...
Article
Full-text available
Expanding robot autonomy can deliver functional flexibility and enable fast deployment of robots in challenging and unstructured environments. In this direction, significant advances have been recently made in visual-perception driven autonomy, which is mainly due to the availability of rich sensory data-sets. However, current robots’ physical inte...
Conference Paper
Full-text available
In this paper, we propose a method for improving the human operator's arm posture during bilateral teleoperation. The method is based on a musculoskeletal model that considers human operator's arm dynamics and the feedback force from the haptic interface (master), which is used to control a robotic arm (slave) in a remote environment. We perform an...
Preprint
The development of new materials/actuators in robotics leads to the rapid growth of new types of robots, including soft/continuum robots, reconfigurable robots, exoskeleton robots, haptic master devices, and so on. When designing a new robot, the orientability is an important performance index to evaluate its dexterities. However, a theoretical inv...
Preprint
The Incomplete Orientation Constraint (IOC), which exist widely in a lot of robotic tasks, e.g. arc-welding, engraving, etc., do not require a controlled motion constrained by all three spatial directions. The trajectory tracking control with IOC remains a challenge for existing methods, due to the nonlinear structure of the rotation group SO(3). T...
Article
Full-text available
Solving mobile manipulation tasks in inaccessible and dangerous environments is an important application of robots to support humans. Example domains are construction and maintenance of manned and unmanned stations on the moon and other planets. Suitable platforms require flexible and robust hardware, a locomotion approach that allows for navigatin...
Article
Despite the development of numerous trajectory planners based on computationally fast algorithms targeting accurate motion of robots, the nowadays robotic applications requiring compliance for interaction with environment demand more comprehensive schemes to cope with unforeseen situations. This paper discusses the problem of online Cartesian traje...
Article
Full-text available
Teleoperation systems require a human-centered approach in which the kinematic mapping is intuitive and straightforward for the operators. However, a mismatch in the degrees-of-freedom (DoFs) between master and slave could result in an asymmetrical teleoperation system. That is an obstacle for intuitive kinematic mapping. In particular, it is even...
Conference Paper
Full-text available
Orientability is an important performance index to evaluate the dexterity of haptic master devices that are of great importance in teleoperated/simulated environments. Currently, most of the existing haptic master devices have limited workspace and limited dexterity. In this paper, we present the RemoT-ARM, a 6 Degree-of-Freedom (DOF) haptic master...
Conference Paper
Full-text available
Torque distribution in redundant robots that combine the potential of asymmetric series-parallel actuated branches and multi-articulation pose a non-trivial challenge. To address the problem, this work proposes a novel optimization based controller that can accommodate various quadratic criteria to perform the torque distribution among dissimilar s...
Article
The widespread use of robotics in new application domains beyond industrial workplace settings necessitates systems that demonstrate functionalities far exceeding those of classical industrial robotic machines. These emerging applications involve complex tasks that vary and that must be carried out within a partially unknown environment, requiring...
Article
Full-text available
The manufacturing industry is among the top wealthgenerating sectors of the global economy and accounted for 15.3% and 10%, respectively, of the total European and American workforce in 2018 [1], [2]. Despite its crucial role, manufacturing is facing a critical challenge based on a reduction of skilled labor availability. This trend is impos- ing a...
Preprint
The workspace limit to map the master’s motion to a reachable workspace of the slave is fundamental for a teleoperation system. Although numerous workspace determination methods have been studied, the workspace limit approach still remains challenging. The main difficulty is that the computation of the mapping from an unreachable point to its corre...
Article
Legged-wheeled robots combine the advantages of efficient wheeled mobility with the capability of adapting to real-world terrains through the legged locomotion. Thanks to their hybrid mobility skill, they can excel in many application scenarios where other mobile platforms are not suitable for. However, the improved versatility of their mobility in...
Conference Paper
Full-text available
Hybrid legged-wheeled robots such as the CENTAURO, are capable of varying their footprint polygon to carry out various agile motions. This property can be advantageous for wheeled-only planning in cluttered spaces, which is our focus. In this paper, we present an improved algorithm that builds upon our previously introduced preliminary footprint va...
Preprint
Teleoperation systems require a human-centered approach in which the kinematic mapping is intuitive and straightforward for the operators. However, a mismatch in the degrees-of-freedom (DoFs) between master and slave could result in an asymmetrical teleoperation system. That is an obstacle for intuitive kinematic mapping. In particular, it is even...
Article
Full-text available
The need for robots operating in the real-world has sparked interest in hybrid locomotion that combines the versatile legged mobility with a simpler wheeled motion. The use of legged-wheeled robots in complex real-world scenarios requires controllers that will capitalise on this flexibility. In this work, a reactive control scheme that exploits whe...
Article
Performing a demanding manipulation task with a multi-legged loco-manipulation platform may require the exploitation of multiple external contacts with different environment surfaces for counteracting the manipulation forces. This is the case of the pushing task of a heavy object, where the grip forces at ground may not be adequate and establishing...
Article
This work deals with the kinematic control of Centauro , a highly redundant, hybrid wheeled-legged robot designed at Istituto Italiano di Tecnologia (IIT) . Given its full wheeled mobility as allowed by its four independently steerable wheels, the choice of some local frame (in addition to the global world) is required in order to express tasks...
Article
Full-text available
We present the development, modeling, and control of a three-degree-of-freedom compliantly actuated leg called the eLeg, which employs both series- and parallel-elastic actuation as well as a bio-inspired biarticular tendon. The leg can be reconfigured to use three distinct actuation configurations, to directly compare with a state-of-the-art serie...
Article
Full-text available
Five years after the DARPA Robotics Challenge (DRC) and close to the 50th anniversary of the first fullscale anthropomorphic robot developed in the world, it is our great pleasure to present the first IEEE Robotics and Automation Magazine special issue on humanoid robot applications in real-world scenarios. The aim of this special issue is to colle...
Article
In humanoid robotic platforms, classical inverse kinematics algorithms, based on L2-regularization of joint velocities or accelerations, tends to engage the motion of all the available degrees of freedom, resulting in movements of the whole robot structure, which are inherently not sparse . The role of sparsity in motion control has recently gain...
Conference Paper
Full-text available
Hybrid legged-wheeled robots are able to adapt their leg configuration and height to vary their footprint polygons and go over obstacles or traverse narrow spaces. In this paper, we present a variable configuration wheeled motion planner based on the A* algorithm. It takes advantage of the agility of hybrid wheeled-legged robots and plans paths ove...