81 accepted papers
We propose a contact-explicit hierarchical architecture coupling Reinforcement Learning (RL) and Model Predictive Control (MPC), where a high-level RL agent provides gait and navigation commands to a low-level locomotion MPC. This off loads the combinatorial burden of contact timing from the MPC by
The administration and monitoring of shared workspaces are crucial for seamlessly integrating robots to operate in close interactions with humans. Adaptive, versatile, and reliable robot movements are key to achieving effective and successful human-robot synergy. In situations involving unexpected o
Non-prehensile pushing to move and reorient objects to a goal is a versatile loco-manipulation skill. In the real world, the object's physical properties and friction with the floor contain significant uncertainties, which makes the task challenging for a mobile manipulator. In this paper, we develo
Robotics has shown significant potential in assisting people with disabilities to enhance their independence and involvement in daily activities. Indeed, a societal long-term impact is expected in home-care assistance with the deployment of intelligent robotic interfaces. This work presents a human-
This work introduces a novel parallel elastic actuation principle designed to provide torque compensation for legged robots. Unlike existing solutions, the proposed concept leverages a nitrogen N<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"
Ground reaction force information, which includes the location of the center of pressure (COP) and vertical ground reaction force (vGRF), has various applications, such as in the gait assessment of patients post-injury or in the control of robot prostheses and exoskeleton devices. At the beginning o
Modular reconfigurable manipulators enable quick adaptation and versatility to address different application environments and tailor to the specific requirements of the tasks. Task performance significantly depends on the manipulator’s mounted pose and morphology design, therefore posing the need of…
Hand motion tracking is essential in many fields, e.g., immersive virtual reality, teleoperation of robotic hand, and hand rehabilitation of stroke patient, as human hand plays a crucial role in our daily life. The highly under-actuated hand exoskeleton, which can track the 6-DoF motions of each fin…
This work presents a reactive control strategy for loading and sudden unloading of an elbow effort-compensation device controlled in force. Through this control strategy, in addition to an individual's forearm weight, an external load can be detected and adaptively compensated via a feed-forward for
Performing autonomous navigation in cluttered and unstructured terrains still remains a challenging task for legged and wheeled mobile robots. To accomplish such a task, online planners shall incorporate new terrain information perceived while the robot is moving within its environment. While hybrid
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 th…
Actuation failure and fault-tolerant control under the actuation failure scenario have drawn more attention in accordance with the recent increasing demand for reliable robot control applications such for long-term and remote operation. The emergence of control torque loss, i.e., the free-swinging f
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 t…
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
The use of assistive technologies in industrial environments to improve human ergonomics and comfort in repetitive and high effort tasks have increased considerably in the last decade. Predominantly, the goal is to provide additional physical support through lightweight and wearable devices, without…
The workspace limit to smoothly map unreachable motions sensed in the leader side$^1$ 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 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 count…
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 expl
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…
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 let
This paper presents a framework providing a full pipeline to execute a complex physical interaction behaviour of a humanoid bipedal robot, both from a theoretical and a practical standpoint. Building from a multi-contact control architecture that combines contact planning and reactive force distribu…
Orientability is an important performance index to evaluate the dexterity of haptic master devices. 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 device that can p…
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
Hybrid legged-wheeled robots such as the CEN-TAURO, 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…
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
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 intui
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 for
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
Human Robot interaction is a fundamental perquisite for any robot performing a physical task in collaboration with a human. The presence of disturbances arising from the partially known tasks payloads, the unexpected interaction forces in general, and the uncertainty in the interpretation of the hum…
The deployment of robotics in real-world scenarios, which may involve harsh and irregular physical interactions with the environment, such as those when robots operating in a disaster scenario, or the interactions that prosthetic devices may experience, demands hardware, which is physically resilien
Despite the development of a large number of mobile manipulation robots, very few platforms can demonstrate the required strength and mechanical sturdiness to accommodate the needs of real-world applications with high payload and moderate/harsh physical interaction demands, e.g., in disaster-respons
This work introduces a framework for the Cartesian control of multi-legged, highly redundant robots. The proposed framework allows the untrained user to perform complex motion tasks with robotics platforms by leveraging a simple, auto-generated ROS-based interface. Contrary to other motion control f…
As robotic systems become more flexible and intelligent, they must be able to move into environments with a high degree of uncertainty or clutter, such as our homes, workplaces, and the outdoors. In these unstructured scenarios, it is possible that the body of the robot collides with its surrounding…
Humans commonly exploit interaction with the environment constraints to assist the execution of the loco-manipulation tasks they perform. One particular example is the exploration of contacts during manipulation to relax the loading of those arm joints that are not directly involved in the generatio…
Contemporary humanoids are equipped with visual and LiDAR sensors that are effectively utilized for Visual Odometry (VO) and LiDAR Odometry (LO). Unfortunately, such measurements commonly suffer from outliers in a dynamic environment, since frequently it is assumed that only the robot is in motion a…
In this paper, we look at the challenge of human robot interaction in locomotion. We consider a hand-in-hand interaction scenario where a human compliantly interacts with the upper-body of an impedance controlled humanoid. By exploring the velocity transmission of the robot arms, and the interaction…
Multi-legged humanoid platforms present an inherent redundancy in the number of end-effectors required to perform interaction tasks, such as balancing and manipulation. The most relevant possibility opened up by end-effector redundancy consists in using a subset of the available end-effectors to per
In this paper we propose a novel hybrid walking pattern generator which combines results from the virtual constraints and the preview control theories for bipedal locomotion. This choice is motivated by findings in biomechanics that show how the dynamic motion of the human walk is mainly generated b…
Nowadays, robots are expected to enter in various application scenarios and interact with unknown and dynamically changing environments. This highlights the need for creating autonomous robot behaviours to explore such environments, identify their characteristics and adapt, and build knowledge for f…
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 o…
This paper proposes the implementation of an impedance controller on the ankle level of COMAN+, a robot with parallel kinematics ankles actuated by a dual four-bar mechanism. The main contribution of the work is a realization of said control scheme that grants a less abrupt and safer robot response…
This work presents a novel method for estimating online the torques at the ankle, knee and hip of a user with the goal of generating reference signals for torque controlled lower limb exoskeletons. In particular, this approach attempts to address difficulties arising in real life scenarios when nonc…
Complex interactions with unstructured environments require the application of appropriate restoring forces in response to the imposed displacements. Impedance control techniques provide effective solutions to achieve this, however, their quasi-static performance is highly dependent on the choice of…
This work presents a new attitude balancing strategy implemented and validated on a quadrupedal robot equipped with a custom hybrid wheel-legged mobility system. The proposed method uses an inverse kinematics solution scheme based on Quadratic Programming optimization to generate full body motions t…
In recent years, many different feedback controllers for robotic applications have been proposed and implemented. However, the high coupling between the different software modules made their integration into one common architecture difficult. Consequently, this has hindered the ability of a user to…
We present a wearable skin stretch device for the forearm. It is composed of four cylindrical end effectors, evenly distributed around the user's forearm. They can generate independent skin stretch stimuli at the palmar, dorsal, ulnar, and radial sides of the arm. When the four end effectors rotate
This work presents the development of a 3-DoF leg with series and parallel compliant actuation. Series-elastic main actuators are combined with parallel high efficiency energy storage branches, to substantially improve energy efficiency. The leg design is semi-anthropomorphic, with similar mass and…
This work presents a method to increase the peak output speed of surface permanent magnet synchronous machine (SPMSM) motor drives with application in robotics using field weakening control. Contrary to most existing works, the strategy is stateless and operates using only a motor torque reference a…
Robotics teleoperation has been extensively studied and considered in the past in several task scenarios where direct human intervention is not possible due to the hazardous environments. In such applications, both communication degradation and reduced perception of the remote environment are practi…
Bipedal robots have gained a lot of locomotion capabilities the past few years, especially in the control level. Navigation over complex and unstructured environments using exteroceptive perception, is still an active research topic. In this paper, we present a footstep planning system to produce fo…
This paper introduces the design of a novel under-actuated hand with highly integrated modular finger units, which can be easily reconfigured in terms of finger arrangement and number to account for the manipulation needs of different applications. Each finger module is powered by a single actuator…
In this work we introduced a prioritized Cartesian impedance control under the framework of the Quadratic Programming (QP) optimization. In particular, we present a formulation which is simpler than full inverse dynamics, avoids any matrix pseudo-inversion, inverse kinematics computation and conside…
Legged-wheeled robots combine the advantages of efficient wheeled mobility with the adaptability to real-world terrains through the legged locomotion. Due to this hybrid mobility skill, they can excel in many application scenarios where other mobile platforms are not suitable for. However, their ver…
This paper proposes a novel fall control technique based on energy concepts, which can be applied online to mitigate the impact forces incurred during the falling over of humanoids. The technique reduces the total energy using a nonlinear control tool, called energy shaping (ES), and further distrib…
The endpoint stiffness of the human arm has been long recognized as a key component ensuring the quasi-static stability of the arm physical interactions with the external world. Similarly, the understanding of the joint stiffness behavior can provide complementary insights, e.g., on the underlying s
The present work addresses the generation of a walking gait with automatic footstep placement for a quadrupedal robot, within a Linear Model Predictive Control framework. Existing work has shown how this is only possible within a non-convex programming framework, finding a solution of which is well-…
We present a new method to translate videos to commands for robotic manipulation using Deep Recurrent Neural Networks (RNN). Our framework first extracts deep features from the input video frames with a deep Convolutional Neural Networks (CNN). Two RNN layers with an encoder-decoder architecture are…
Limitations with the on-board computational resources installed on untethered robots such as humanoids and mobile robots in general affects significantly the performance and capabilities of these machines. An approach to address this issue is to make use of the cloud robotics concept and take advant…
Developing a high physical performance robotic manipulation platform with considerable power density, strength and resilience is not a trivial task and frequently leads to heavy and bulky systems unable to meet the application requirements, i.e. such robots should have human body size compatibility…
We present a new method to detect object affordances in real-world scenes using deep Convolutional Neural Networks (CNN), an object detector and dense Conditional Random Fields (CRF). Our system first trains an object detector to generate bounding box candidates from the images. A deep CNN is then u…
Joint torque sensing represents one of the foundations and vital components of modern robotic systems that target to match closely the physical interaction performance of biological systems through the realization of torque controlled actuators. However, despite decades of studies on the development
Series-elastic actuators are quickly becoming the core component of robots operating in real-world environments, allowing for robust, safe, torque-controlled robots. This letter investigates the influence of the selected stiffness and control parameters. By consolidating several analyses, it is show
The work presented herein, attempts to address the problem of designing stepping recovery controllers for compliantly actuated humanoid robots. Based on the decomposition of the stepping procedure into three distinct phases, which are characterized by unique combinations of configurations and impeda…
This contribution compares two approaches for applying disturbance observers (DOBs) to the torque control problem of series elastic actuators (SEAs). It is demonstrated that they are in fact equivalent for linear models in terms of their ability to reject disturbances and enforce nominal model dynam…
The development of energy efficient actuation represents one of the biggest challenges in robotics research today. This letter presents the generalisation of design and control concepts for a recently introduced asymmetric compliant actuator, as well as its extension to multi-DoF articulated robotic
The general approach to humanoid feet design considers the use of rectangular plate sole structures that are relatively stiff and compatible for flat terrain locomotion. Although this can be adequate the inability of these stiff feet to cope with small terrain irregularities, it makes them inappropr
We present a novel and real-time method to detect object affordances from RGB-D images. Our method trains a deep Convolutional Neural Network (CNN) to learn deep features from the input data in an end-to-end manner. The CNN has an encoder-decoder architecture in order to obtain smooth label predicti…
Exoskeletons offer an intuitive method for actuating multiple DOF of the body; this makes them attractive for applications where generation and coupling of artificial forces to the limbs is needed. Force feedback hand exoskeletons have been continuously considered for whole hand haptic interaction i…
This paper describes a new task-oriented grasping method to reorient a rigid object to its nominal pose, which is defined as the configuration that it needs to be grasped from, in order to successfully execute a particular manipulation task. Our method combines two key insights: (1) a visual 6 Degre…
In this work, to guarantee the Pisa/IIT SoftHand's grasp robustness against slippage, three reflex control modes, namely Current, Pose and Impedance, are implemented and experimentally evaluated. Towards this objective, ThimbleSense fingertip sensors are designed and integrated into the thumb and mi
This work presents the development of iT-Knee, a novel modular knee exoskeleton that makes use of a torque transmission interface to deliver pure assistive torque to the knee articulation, with the objective to act as rehabilitation tool, or a single joint add-on exoskeleton device for power augment…
In this paper we present a novel whole-body compliance framework. It is based on the Multi Spring Model, a set of virtual springs interconnecting the limb extremities and the trunk as well. More specifically, six virtual springs connect the trunk of the robot to the feet and the hands and other six…
The work presents the development and evaluation of a novel foot sole for humanoid robots. For humanoid locomotion the foot sole is important for absorbing impacts. In contrast to the simple planar rubber pad foot sole that is conventionally used in humanoid robots this paper introduces a new foot s…
Effective and stable execution of a remote manipulation task in an uncertain environment requires that the task force and position trajectories of the slave robot be appropriately commanded. To achieve this goal, in teleimpedance control, a reference command which consists of the stiffness and posit…
The development of variable impedance actuators (VIAs) has highlighted the need for proper control of passive impedance to attain suitable interaction performance. Until recently the regulation of the intrinsic impedance in VIAs is achieved in an open-loop model-based manner, mainly due to the lack…
In this paper, we propose an Energy based Fall Prediction (EFP) which observes the real-time balance status of a humanoid robot during standing. The EFP provides an analytic and quantitative measure of the level of balance. Both simulation and experimental studies were conducted and compared with th…
This paper aims at developing a unified and adaptive foot placement control for legged robots. The locomotion control of legged robots can be classified into three parts as body height control, body attitude control, and forward velocity control. In our study, the body attitude is controlled at stan…
It is well known that kinematics can significantly affect the manipulation capabilities of robotic arms, traditionally illustrated by performance indices such as workspace volume, kinematic and force manipulability, and isotropy within the arm workspace. In the case of dual-arm systems and bimanual…
The stiffness ellipsoid, i.e. the locus of task-space forces obtained corresponding to a deformation of unit norm in different directions, has been extensively used as a powerful representation of robot interaction capabilities. The size and shape of the stiffness ellipsoid at a given end-effector p…
We propose a new algorithm capable of online regeneration of gait patterns. The algorithm uses a nonlinear optimization technique to find step parameters that will bring the robot from the present state to a desired state. It modifies online not only the footstep positions, but also the step timing…
A fundamental aspect of controlling humanoid robots lies in the capability to exploit the whole body to perform tasks. This work introduces a novel whole body control library called OpenSoT. OpenSoT is combined with joint impedance control to create a framework that can effectively generate complex…