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Christos Bergeles

33 accepted papers

2026

Toward AI Autonomous Navigation for Mechanical Thrombectomy Using Hierarchical Modular Multi-Agent Reinforcement Learning (HM-MARL)

RA-L 2026

Mechanical thrombectomy (MT) is typically the optimal treatment for acute ischemic stroke involving large vessel occlusions, but access is limited due to geographic and logistical barriers. Reinforcement learning (RL) shows promise in autonomous endovascular navigation, but generalization across ‘lo

Cited by 1SourceScholar
2025

Uncertainty-Aware Shared Control for Vision-Based Micromanipulation

IROS 2025

This paper presents an uncertainty-aware shared control and calibration method for micromanipulation using a digital microscope and a tool-mounted, multi-joint robotic arm, integrating real-time human intervention with a visual-motor policy. Our calibration algorithm leverages co-manipulation contro

Cited by 2SourceScholar
2025

Vine4Spine: A Steerable Tip-Growing Robot with Contact Force Estimation for Navigation in the Spinal Subarachnoid Space

IROS 2025

Therapies targeting neurodegenerative diseases via brain ventricles and spinal parenchyma face delivery challenges. Systemic administration is ineffective due to the blood-brain barrier, while direct surgical access, especially for multi-site delivery, is highly invasive. The spinal subarachnoid spa

Cited by 2SourceScholar
2024

Excitation Trajectory Optimization for Dynamic Parameter Identification Using Virtual Constraints in Hands-on Robotic System

ICRA 2024poster

This paper proposes a novel, more computationally efficient method for optimizing robot excitation trajectories for dynamic parameter identification, emphasizing self-collision avoidance. This addresses the system identification challenges for getting high-quality training data associated with co-ma…

Cited by 4SourceScholar
2024

Lumped Parameter Dynamic Model of an Eversion Growing Robot: Analysis, Simulation and Experimental Validation

ICRA 2024poster

This paper presents a lumped-parameter dynamic model of a pressure driven eversion robot carrying a catheter through its hollow core. A simulation framework based on the model is developed in MATLAB and is used for understanding the underlying physics, for identifying the regions of operation, and f…

Cited by 2SourceScholar
2023

OpTaS: An Optimization-based Task Specification Library for Trajectory Optimization and Model Predictive Control

ICRA 2023poster

This paper presents OpTaS, a task specification Python library for Trajectory Optimization (TO) and Model Predictive Control (MPC) in robotics. Both TO and MPC are increasingly receiving interest in optimal control and in particular handling dynamic environments. While a flurry of software libraries…

Cited by 14SourcecodeScholar
2023

Sim2Real Transfer of Reinforcement Learning for Concentric Tube Robots

RA-L 2023

Concentric Tube Robots (CTRs) are promising for minimally invasive interventions due to their miniature diameter, high dexterity, and compliance with soft tissue. CTRs comprise individual pre-curved tubes usually composed of NiTi and are arranged concentrically. As each tube is relatively rotated an

Cited by 11SourceScholar
2023

Towards a Physics-Based Model for Steerable Eversion Growing Robots

RA-L 2023

Soft robots that grow through eversion/apical extension can effectively navigate fragile environments such as ducts and vessels inside the human body. This paper presents the physics-based model of a miniature steerable eversion growing robot. We demonstrate the robot's growing, steering, stiffening

Cited by 19SourceScholar
2023

Vision-Based Autonomous Steering of a Miniature Eversion Growing Robot

RA-L 2023

This letter presents vision-based autonomous navigation of a steerable soft growing robot. Our experimental platform is the previously presented MAMMOBOT, which is a small-diameter eversion growing robot with an embedded steerable catheter. The current manuscript first models the robot using kinemat

Cited by 8SourceScholar
2022

Design and Quasistatic Modelling of Hybrid Continuum Multi-Arm Robots

ICRA 2022poster

Continuum surgical robots can navigate anatomical pathways to reach pathological locations deep inside the human body. Their flexibility, however, generally comes with reduced dexterity at their tip and limited workspace. Building on recent work on eccentric tube robots, this paper proposes a new co…

Cited by 4SourceScholar
2022

Multi-Scale and Cross-Scale Contrastive Learning for Semantic Segmentation

ECCV 2022poster

"This work considers supervised contrastive learning for semantic segmentation. We apply contrastive learning to enhance the discriminative power of the multi-scale features extracted by semantic segmentation networks. Our key methodological insight is to leverage samples from the feature spaces ema…

2022

ROS-PyBullet Interface: A Framework for Reliable Contact Simulation and Human-Robot Interaction

CoRL 2022poster

Reliable contact simulation plays a key role in the development of (semi-)autonomous robots, especially when dealing with contact-rich manipulation scenarios, an active robotics research topic. Besides simulation, components such as sensing, perception, data collection, robot hardware control, human…

Cited by 22SourcecodeScholar
2022

Real-Time Dynamics of Concentric Tube Robots With Reduced-Order Kinematics Based on Shape Interpolation

RA-L 2022

Concentric tube robots (CTRs) are catheter-like robots that can navigate anatomical lumen to reach surgical targets that are deep inside the body. While CTRs have been extensively studied in quasi-static conditions, unique robot behaviours such as hysteresis and snapping, i.e. the sudden release of

Cited by 13SourceScholar
2021

MAMMOBOT: A Miniature Steerable Soft Growing Robot for Early Breast Cancer Detection

RA-L 2021

This letter presents MAMMOBOT, one of the first millimetre-scale steerable soft growing robots for medical applications. MAMMOBOT aims to access the breast through the nipple and navigate the mammary ducts to detect precursors of invasive breast cancers. Addressing limitations of the state-of-the-ar

Cited by 50SourceScholar
2020

Design, Modeling, and Implementation of a 7-DOF Cable-Driven Haptic Device With a Configurable Cable Platform

RA-L 2020

This letter introduces a novel 7 Degree Of Freedom (DOF) cable-driven haptic device based on the concept of a configurable cable platform. In the proposed concept, a 1-DOF pinch grasping capability is provided via a network of ten passive cables kept in tension. The coordinated action on the cable p

Cited by 16SourceScholar
2020

Exploiting the Morphology of a Shape Memory Spring as the Active Backbone of a Highly Dexterous Tendril Robot (ATBR)

IROS 2020poster

Tendrils are common stable structures in nature and are used for sensing, actuation, and geometrical stiffness modulation. In this paper, for the first time we exploit the helical geometry of a shape memory alloy (SMA) tendril as a simple to fabricate highly dexterous robotic continuum tentacle that…

Cited by 2SourceScholar
2020

Optic Nerve Sheath Fenestration With a Multi-Arm Continuum Robot

RA-L 2020

This article presents a medical robotic system for deep orbital interventions, with a focus on Optic Nerve Sheath Fenestration (ONSF). ONSF is a currently invasive ophthalmic surgical approach that can reduce potentially blinding elevated hydrostatic intracranial pressure on the optic disc via an in

Cited by 22SourceScholar
2020

Stiffness Imaging With a Continuum Appendage: Real-Time Shape and Tip Force Estimation From Base Load Readings

RA-L 2020

In this letter, we propose benefiting from load readings at the base of a continuum appendage for real-time forward integration of Cosserat rod model with application in configuration and tip load estimation. The application of this method is successfully tested for stiffness imaging of a soft tissu

Cited by 31SourceScholar
2019

Autonomous Steering of Concentric Tube Robots for Enhanced Force/Velocity Manipulability

IROS 2019poster

Concentric tube robots (CTR) can traverse tightly curved paths and offer dexterity in constrained environments, making them advantageous for minimally invasive surgical scenarios that experience strict anatomical and surgical constraints. Their shape is controlled via rotation and translation of sev…

Cited by 22SourceScholar
2019

Reduced Order vs. Discretized Lumped System Models with Absolute and Relative States for Continuum Manipulators

RSS 2019poster

A reliable, accurate, and yet simple dynamic model is important to analyze, design and control continuum manipulators. Such models should be fast, as simple as possible and user-friendly to be widely accepted by the ever-growing robotics research community. In this study, we introduce two new modeli…

Cited by 22SourcePDFScholar
2018

Requirements Based Design and End-to-End Dynamic Modeling of a Robotic Tool for Vitreoretinal Surgery

ICRA 2018poster

Despite several robots having been proposed for vitreoretinal surgery, there is limited information on their dynamic modeling. This gap leads to sub-optimal motor selection and hinders the application of advanced control schemes that would fulfill the goal of micro-precise surgery. This paper presen…

Cited by 13SourceScholar
2017

A Continuum Robot and Control Interface for Surgical Assist in Fetoscopic Interventions

RA-L 2017

Twin-twin transfusion syndrome requires interventional treatment using a fetoscopically introduced laser to sever the shared blood supply between the fetuses. This is a delicate procedure relying on small instrumentation with limited articulation to guide the laser tip and a narrow field of view to

Cited by 46SourceScholar
2017

Corner-Based Geometric Calibration of Multi-Focus Plenoptic Cameras

ICCV 2017poster

We propose a method for geometric calibration of multi-focus plenoptic cameras using raw images. Multi-focus plenoptic cameras feature several types of micro-lenses spatially aligned in front of the camera sensor to generate micro-images at different magnifications. This multi-lens arrangement provi…

Cited by 33PDFcodeScholar
2017

Implicit active constraints for concentric tube robots based on analysis of the safe and dexterous workspace

IROS 2017poster

The use of concentric tube robots has recognized advantages for accessing target lesions while conforming to certain anatomical constraints. However, their complex kinematics makes their safe telemanipulation in convoluted anatomy a challenging task. Collaborative control schemes, which guide the op…

Cited by 16SourceScholar
2016

Adaptive nonparametric kinematic modeling of concentric tube robots

IROS 2016poster

Concentric tube robots comprise telescopic precurved elastic tubes. The robot's tip and shape are controlled via relative tube motions, i.e. tube rotations and translations. Non-linear interactions between the tubes, e.g. friction and torsion, as well as uncertainty in the physical properties of the…

Cited by 21SourceScholar
2016

Design and analysis of a wire-driven flexible manipulator for bronchoscopic interventions

ICRA 2016

Bronchoscopic interventions are widely performed for the diagnosis and treatment of lung diseases. However, for most endobronchial devices, the lack of a bendable tip restricts their access ability to get into distal bronchi with complex bifurcations. This paper presents the design of a new wire-dri

Cited by 13SourceScholar
2016

Implicit active constraints for safe and effective guidance of unstable concentric tube robots

IROS 2016poster

Safe and effective telemanipulation of concentric tube robots is hindered by their complex, non-intuitive kinematics. Guidance schemes in the form of attractive and repulsive constraints can simplify task execution and facilitate natural operation of the robot by clinicians. The real-time seamless c…

Cited by 21SourceScholar
2015

A cooperative control framework for haptic guidance of bimanual surgical tasks based on Learning From Demonstration

ICRA 2015poster

Whilst current minimally invasive surgical robots offer many advantages to the surgeon, most of them are still controlled using the traditional master-slave approach, without fully exploiting the complementary strengths of both the human user and the robot. This paper proposes a framework that provi…

Cited by 49SourceScholar
2015

On-line collision-free inverse kinematics with frictional active constraints for effective control of unstable concentric tube robots

IROS 2015poster

Concentric tube robots are catheter-sized robots that are ideally suited for navigating along natural anatomical pathways and treating deep-seated pathologies. Their telemanipulation in dynamic environments requires on-line computation of inverse kinematics with simultaneous avoidance of anatomical…

Cited by 33SourceScholar
2015

Vision-based intraoperative shape sensing of concentric tube robots

IROS 2015poster

Concentric tube robots have shown promise for minimally invasive surgical (MIS) tasks that require navigation via tortuous anatomical paths. Despite extensive research on their kinematic and dynamic modelling, however, inaccuracies and deformations of their shape due to unknown loads and collisions…

Cited by 38SourceScholar