Claudio Semini

Claudio Semini
Istituto Italiano di Tecnologia | IIT · Dynamic Legged Systems

PhD
2 PostDoc openings in my lab: https://dls.iit.it/openings

About

144
Publications
79,331
Reads
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3,845
Citations
Introduction
Claudio Semini is the Head of the Dynamic Legged Systems (DLS) lab at IIT, Genoa, Italy. He received an MSc degree in EE and IT from ETH Zurich, Switzerland, in 2005. From 2004 to 2006, he first visited the Hirose Lab at Tokyo Tech, and later the Toshiba R&D Center, Japan. In 2010 he obtained his PhD degree from IIT/UniGE, stayed on as PostDoc and leads the DLS lab since 2012. His research focuses on quadruped robot design, legged locomotion, hydraulic actuation, etc. web: dls.iit.it
Additional affiliations
August 2013 - present
Istituto Italiano di Tecnologia
Position
  • Head of Department

Publications

Publications (144)
Conference Paper
Full-text available
We propose a reactive controller framework for robust quadrupedal locomotion, designed to cope with terrain irregularities, trajectory tracking errors and poor state estimation. The framework comprises two main modules: One related to the generation of elliptic trajectories for the feet and the other for control of the stability of the whole robot....
Article
Full-text available
In legged locomotion, the projection of the robot’s Center of Mass (CoM) being inside the convex hull of the contact points is a commonly accepted sufficient condition to achieve static balancing. However, some of these configurations cannot be realized because the joint-torques required to sustain them would be above their limits (actuation limits...
Preprint
Full-text available
Developing feasible body trajectories for legged systems on arbitrary terrains is a challenging task. Given some contact points, the trajectories for the Center of Mass (CoM) and body orientation, designed to move the robot, must satisfy crucial constraints to maintain balance, and to avoid violating physical actuation and kinematic limits. In this...
Chapter
https://link.springer.com/content/pdf/10.1007%2F978-3-642-41610-1_59-1.pdf
Preprint
Full-text available
Quadrupedal manipulators require to be compliant when dealing with external forces during autonomous manipulation, tele-operation or physical human-robot interaction. This paper presents a whole-body controller that allows for the implementation of a Cartesian impedance control to coordinate tracking performance and desired compliance for the robot...
Preprint
Full-text available
Model Predictive Control (MPC) approaches are widely used in robotics, since they allow to compute updated trajectories while the robot is moving. They generally require heuristic references for the tracking terms and proper tuning of parameters of the cost function in order to obtain good performance. When for example, a legged robot has to react...
Conference Paper
Full-text available
The exploration of lunar craters is of high interest, but their rugged and inclined terrain also exceeds the mobility capabilities of current rovers, opening up a field of application for legged exploration systems. This paper presents a navigation and locomotion control system that enables legged robots to be able to perceive the terrain, to plan...
Article
Full-text available
Legged robots are meant to autonomously navigate unstructured environments for applications like search and rescue, inspection, or maintenance. In autonomous navigation, a close relationship between locomotion and perception is crucial; the robot has to perceive the environment and detect any change in order to autonomously make decisions based on...
Preprint
Full-text available
Re-planning in legged locomotion is crucial to track the desired user velocity while adapting to the terrain and rejecting external disturbances. In this work, we propose and test in experiments a real-time Nonlinear Model Predictive Control (NMPC) tailored to a legged robot for achieving dynamic locomotion on a variety of terrains. We introduce a...
Preprint
Full-text available
Grapevine winter pruning is a complex task, that requires skilled workers to execute it correctly. The complexity makes it time consuming. It is an operation that requires about 80-120 hours per hectare annually, making an automated robotic system that helps in speeding up the process a crucial tool in large-size vineyards. We will describe (a) a n...
Preprint
Full-text available
Grapevine winter pruning is a complex task, that requires skilled workers to execute it correctly. The complexity of this task is also the reason why it is time consuming. Considering that this operation takes about 80-120 hours/ha to be completed, and therefore is even more crucial in large-size vineyards, an automated system can help to speed up...
Preprint
Full-text available
Mobile manipulators that combine mobility and manipulability, are increasingly being used for various unstructured application scenarios in the field, e.g. vineyards. Therefore, the coordinated motion of the mobile base and manipulator is an essential feature of the overall performance. In this paper, we explore a whole-body motion controller of a...
Article
Full-text available
Classic control theory applied to compliant and soft robots generally involves an increment of computation that has no equivalent in biology. To tackle this, morphological computation describes a theoretical framework that takes advantage of the computational capabilities of physical bodies. However, concrete applications in robotic locomotion cont...
Article
Locomotion over soft terrain remains a challenging problem for legged robots. Most of the work done on state estimation for legged robots is designed for rigid contacts, and does not take into account the physical parameters of the terrain. That said, this letter answers the following questions: how and why does soft terrain affect state estimation...
Preprint
Full-text available
Locomotion over soft terrain remains a challenging problem for legged robots. Most of the work done on state estimation for legged robots is designed for rigid contacts, and does not take into account the physical parameters of the terrain. That said, this letter answers the following questions: how and why does soft terrain affect state estimation...
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...
Conference Paper
Full-text available
Estimation of a quadruped's state is fundamentally important to its operation. In this paper we develop a low-level state estimator for quadrupedal robots that includes attitude, odometry, ground reaction forces, and contact detection. The state estimator is divided into three parts. First, a nonlinear observer estimates attitude by fusing inertial...
Conference Paper
Full-text available
This paper presents novel datasets of the hydraulically actuated robot HyQ's proprioceptive sensors. All of the datasets include absolute and relative joint encoders, joint force and torque sensors, and MEMS-based and fibre optic-based inertial measurement units (IMUs). Additionally, a motion capture system recorded the ground truth data with milli...
Preprint
Full-text available
The ability of legged systems to traverse highly-constrained environments depends by and large on the performance of their motion and balance controllers. This paper presents a controller that excels in a scenario that most state-of-the-art balance controllers have not yet addressed: line walking, or walking on nearly null support regions. Our appr...
Article
Full-text available
Planning whole-body motions while taking into account the terrain conditions is a challenging problem for legged robots since the terrain model might produce many local minima. Our coupled planning method uses stochastic and derivatives-free search to plan both foothold locations and horizontal motions due to the local minima produced by the terrai...
Conference Paper
Full-text available
Advances in legged robotics are strongly rooted in animal observations. A clear illustration of this claim is the generalization of Central Pattern Generators (CPG), first identified in the cat spinal cord, to generate cyclic motion in robotic locomotion. Despite a global endorsement of this model, physiological and functional experiments in mammal...
Preprint
Advances in legged robotics are strongly rooted in animal observations. A clear illustration of this claim is the generalization of Central Pattern Generators (CPG), first identified in the cat spinal cord, to generate cyclic motion in robotic locomotion. Despite a global endorsement of this model, physiological and functional experiments in mammal...
Article
Full-text available
We present experimental results using a passive whole-body control approach for quadruped robots that achieves dynamic locomotion while compliantly balancing the robot’s trunk. We formulate the motion tracking as a Quadratic Program(QP) that takes into account the full robot rigid body dynamics,the actuation limits, the joint limits and the contact...
Article
Whole-Body Control (WBC) has emerged as an important framework in locomotion control for legged robots. However, most WBC frameworks fail to generalize beyond rigid terrains. Legged locomotion over soft terrain is difficult due to the presence of unmodeled contact dynamics that WBCs do not account for. This introduces uncertainty in locomotion and...
Preprint
Full-text available
We propose two feasibility constraints to be included in a Single Rigid Body Dynamics-based trajectory optimizer in order to obtain robust motions for quadruped robots in challenging terrain. The former finds an approximate relationship between joint-torque limits and admissible contact forces without requiring the knowledge of the joints' configur...
Preprint
We present a novel control strategy for dynamic legged locomotion in complex scenarios, that considers information about the morphology of the terrain in contexts when only on-board mapping and computation are available. The strategy is built on top of two main elements: first a contact sequence task that provides safe foothold locations based on a...
Preprint
Full-text available
Whole-body Control (WBC) has emerged as an important framework in locomotion control for legged robots. However, most of WBC frameworks fail to generalize beyond rigid terrains. Legged locomotion over soft terrain is difficult due to the presence of unmodeled contact dynamics that WBCs do not account for. This introduces uncertainty in locomotion a...
Preprint
Full-text available
In legged locomotion the projection of the robot’s Center of Mass (CoM) being inside the convex hull of the contact points is a commonly accepted sufficient condition to achieve static balancing. However, some of these configurations cannot be realized because joint-torques required to sustain them would be above their limits (actuation limits). In...
Preprint
Full-text available
We present experimental results using a passive whole-body control approach for quadruped robots that achieves dynamic locomotion while compliantly balancing the robot’s trunk. We formulate the motion tracking as a Quadratic Program (QP) that takes into account the full robot rigid body dynamics, the actuation limits, the joint limits and the conta...
Data
video to the paper: Fast and Continuous Foothold Adaptation for Dynamic Locomotion through CNNs
Article
Full-text available
Legged robots can outperform wheeled machines for most navigation tasks across unknown and rough terrains. For such tasks, visual feedback is a fundamental asset to provide robots with terrain-awareness. However, robust dynamic locomotion on difficult terrains with real-time performance guarantees remains a challenge. We present here a real-time, d...
Preprint
Full-text available
Legged robots are becoming popular not only in research, but also in industry, where they can demonstrate their superiority over wheeled machines in a variety of applications. Either when acting as mobile manipulators or just as the all-terrain ground vehicles, these machines need to precisely track desired base and end-effector trajectories, perfo...
Chapter
Full-text available
The quality of visual feedback can vary signif- icantly on a legged robot meant to traverse unknown and unstructured terrains. The map of the environment, acquired with online state-of-the-art algorithms, often degrades after a few steps, due to sensing inaccuracies, slippage and unexpected disturbances. If a locomotion algorithm is not designed to...
Preprint
Legged robots can outperform wheeled machines for most navigation tasks across unknown and rough terrains. For such tasks, visual feedback is a fundamental asset to provide robots with terrain-awareness. However, robust dynamic locomotion on difficult terrains with real-time performance guarantees remains a challenge. Indeed, the computational effo...
Article
Full-text available
Traditional motion planning approaches for multi-legged locomotion divide the problem into several stages, such as contact search and trajectory generation. However, reasoning about contacts and motions simultaneously is crucial for the generation of complex whole-body behaviors. Currently, coupling theses problems has required either the assumptio...
Article
Full-text available
Hydraulic actuation is the most widely used alternative to electric motors for legged robots and manipulators. It is often selected for its high power density, robustness and high-bandwidth control performance that allows the implementation of force/impedance control. Force control is crucial for robots that are in contact with the environment, sin...
Preprint
Full-text available
The quality of the visual feedback can vary significantly on a legged robot that is meant to traverse unknown and unstructured terrains. The map of the environment, acquired with online state-of-the-art algorithms, often degrades after a few steps, due to sensing inaccuracies, slippage and unexpected disturbances. When designing locomotion algorith...
Data
file also available at: https://www.youtube.com/watch?v=vUx5b5kfRfE&feature=youtu.be
Chapter
Full-text available
What should a legged robot do when it slips? When traction is lost, the locomotion can be irreversibly hampered. Being able to detect slippage at the very beginning and promptly recover the traction is crucial for body stability and can make the difference in a situation where falling is not an option. Indeed, the majority of locomotion controllers...
Preprint
Full-text available
Legged robots promise an advantage over traditional wheeled systems, however, most legged robots are still confined to structured and flat environments. One of the main reasons for this is the difficulty in planning complex whole-body motions while taking into account the terrain conditions. This problem is very high-dimensional as it considers the...
Article
Full-text available
Motion planning in multi-contact scenarios has recently gathered interest within the legged robotics community, however actuator force/torque limits are rarely considered. We believe that these limits gain paramount importance when the complexity of the terrains to be traversed increases. We build on previous research from the field of robotic gras...
Article
The motivation of our current research is to devise motion planners for legged locomotion that are able to exploit the robot's actuation capabilities. This means, when possible, to minimize joint torques or to propel as much as admissible when required. For this reason we define two new 6 dimensional bounded polytopes that we name Actuation-consist...
Conference Paper
Full-text available
The successful execution of complex modernrobotic tasks often relies on the correct tuning of a large number of parameters. In this paper we present a methodology for improving the performance of a trotting gait by learning the gait parameters, impedance profileandthe gains of the control architecture. We show results on a set of terrains, for vari...
Conference Paper
Full-text available
Hydraulic actuators benefit robotic systems as they can produce significant force/torque for their size and are robust. However, their dynamic behavior is highly nonlinear, making high-performance closed-loop control a challenging task. With articulated robotic systems, the associated nonlinear multibody dynamics make the control design task even mor...