33 accepted papers
Robotic grasping of a target object in cluttered environments poses considerable challenges, often due to limited collision-free grasp affordances caused by the close proximity of other objects. To overcome this limitation, non-prehensile actions like pushing can be strategically employed to manipul…
In this work, a methodology to find the best view of a grape stem and approach angle in order to crop it is proposed. The control scheme is based only on a classified point cloud obtained by the in-hand camera attached to the robot’s end effector without continuous stem tracking. It is shown that th…
In this work a control scheme is proposed to enforce dynamic obstacle avoidance constraints to the full body of actively compliant robots. We argue that both compliance and accuracy are necessary to build safe collaborative robotic systems; obstacle avoidance is usually not enough, due to the relian…
In robotic assisted surgeries, surgical tools are inserted into the human body via an incision point in the abdominal wall, which is imposed as a remote center of motion (RCM). The selection of the incision's point location in the human body is critical for the success of the surgical procedure. In…
In this work, a robot control method is proposed for dragging an object by applying top contact forces under unknown friction and object dynamics. This is a non-prehensile manipulation of an object that can enhance the grasping capabilities of a robotic manipulator in a plethora of grasping scenario…
We consider the problem of controlling a bilateral leader-follower robotic surgical set-up to allow kinesthetic haptic feedback to the user when the instrument approaches a forbidden area like sensitive organs arteries or veins that should be protected from injuries during surgery. The leader is a h…
Kinesthetic teaching allows the direct skill transfer from the human to the robot and has been widely used to teach single arm tasks intuitively. In the bi-manual case, simultaneously moving both end-effectors is challenging due to the high physical and cognitive load imposed to the user. Thus, prev…
Robotic grasping in highly cluttered environments remains a challenging task due to the lack of collision free grasp affordances. In such conditions, non-prehensile actions could help to increase such affordances. We propose a multi-fingered push-grasping policy that creates enough space for the fin
In this work, a novel Dynamic Movement Primitive (DMP) formulation is proposed which supports reversibility, i.e. backwards reproduction of a learned trajectory. Apart from sharing all favourable properties of the original DMP, decoupling the teaching of position and velocity profiles and bidirectio…
This letter proposes a controller for stable grasping of unknown-shaped objects by two robotic fingers with tactile fingertips. The grasp is stabilised by rolling the fingertips on the contact surface and applying a desired grasping force to reach an equilibrium state. The validation is both in simu
Trajectory tracking in the orientation space utilizing unit quaternions yields non linear error dynamics as opposed to Cartesian position. In this work, we study trajectory tracking in the orientation space utilizing the most popular quaternion error representations and angular velocity errors. By s…
In this work, the problem of human-robot collaborative object transfer to unknown target poses is addressed. The desired pattern of the end-effector pose trajectory to a known target pose is encoded using DMPs (Dynamic Movement Primitives). During transportation of the object to new unknown targets,…
Kinesthetic teaching allows the direct skill transfer from the human to the robot through physical human-robot interaction. However, it is heavily affected by the robot’s dynamics and the control scheme utilized for the physical interaction. In this work, we aim at assisting the human-teacher by red…
Prehensile robotic grasping of a target object in clutter is challenging because, in such conditions, the target touches other objects, resulting to the lack of collision free grasp affordances. To address this problem, we propose a modular reinforcement learning method which uses continuous actions
A control scheme consisting of a novel coupling of a DMP based virtual reference with a low stiffness controlled robot is proposed. The overall system is proved to achieve superior tracking of a DMP encoded trajectory and accurate target reaching with respect to the conventional scheme under the pre
Over the last decades, Learning from Demonstration (LfD) has become a widely accepted solution for the problem of robot programming. According to LfD, the kinematic behavior is "taught" to the robot, based on a set of motion demonstrations performed by the human-teacher. The demonstrations can be ei…
In this work, we propose an augmentation to the Dynamic Movement Primitives (DMP) framework which allows the system to generalize to moving goals without the use of any known or approximation model for estimating the goal's motion. We aim to maintain the demonstrated velocity levels during the execu…
This paper presents a teaching by demonstration method for contact tasks with periodic movement on planar surfaces of unknown pose. To learn the motion on the plane, we utilize frequency oscillators with periodic movement primitives and we propose modified adaptation rules along with an extraction m…
Extracting a known target object from a pile of other objects in a cluttered environment is a challenging robotic manipulation task encountered in many robotic applications. In such conditions, the target object touches or is covered by adjacent obstacle objects, thus rendering traditional grasping…
Dynamic movement primitives (DMP) are an efficient way for learning and reproducing complex robot behaviors. A singularity free DMP formulation for orientation in the Cartesian space is proposed by Ude et al. [1] and has been largely adopted by the research community. In this work, we demonstrate th
In this work, a passive physical human-robot interaction (pHRI) controller is proposed to intraoperatively ensure that sensitive tissues will not be damaged by the robot's tool. The proposed scheme uses the point cloud of the restricted region's surface as constraint definition and Artificial Potent…
Bimanual assembly of two parts require that a relative target pose is reached prior to the joining operation. Rather than utilizing one arm as a fixture for holding one of the parts while the other performs the assembly, motion generation in the relative end-effector frame is proposed that involves…
In this paper we propose a grasp strategy which exploits environmental contact for grasping domestic flat objects placed or hinged on support surfaces. The proposed grasp strategy considers the non-convex geometry of the object-surface combination, as this appears in objects like plates on tables or…
Progressive automation is a method that allows the operator to demonstrate a task a few times until the robot gradually learns to execute it autonomously. In this letter, we combine a novel structure of dynamic movement primitives (DMP) with variable stiffness control, to allow synchronization with
This video features RAMCIP, a new service robot developed to provide proactive and discreet assistance to elderly with Mild Cognitive Impairments (MCI), supporting their daily activities at home. Starting with a thorough analysis of needs and requirements of the target population, the RAMCIP robot w…
This work proposes the utilization of sinc functions as kernels of Dynamic Movement Primitives (DMP) models for encoding point-to-point kinematic behaviors. The proposed method presents a number of advantages with respect to the state of the art, as it (i) involves a simple learning technique, (ii)…
Real-time grasp stability is based on successful slippage detection. In this work, we consider slippage detection as a binary problem (slip, stable) and we propose a novel set of temporal and frequential features, extracted from force norm profiles and collected during reliable ground truth labeling
The problem of real-time motion generation to a target with obstacle avoidance is considered. A second-order dynamical system having the target as a unique globally asymptotically stable equilibrium is modified in the presence of obstacles by an additive signal whose design is based on the prescribe
The problem of robot joint position and velocity tracking with prescribed performance guarantees is considered. The proposed controller is able to guarantee a prescribed transient and steady state behavior for the position and the velocity tracking errors without utilizing either the robot dynamic m
A human-inspired hand-over control strategy is proposed for the haptic interaction of two dual-fingered hands for the planar case. It is based on a grasp controller for an unknown object which achieves, via fingertip rolling, a stable grasp and a real object mass estimation. Object load transfer is…
This work proposes a kinematic control method for human-robot handshake motions achieving fast motion synchronization given a preset internal robot handshake motion and a compliance level that reflects the robot's level of passiveness. The proposed method combines a non-linear dynamic system having…
In this work a modification of a Cartesian impedance controller is presented. The proposed controller guarantees compliance of the operated manipulator strictly within preselected spatial limits. Specifically, by introducing a nonlinear stiffness term into the control design, the manipulator is prev…
The rolling motion of a soft robotic fingertip is in this paper explicitly included in the control objectives together with the force/position regulation targets. A model based control law is proposed to linearize and decouple the system with respect to the force/position and sliding dynamics based…