Stefano Stramigioli

University of Twente | UT · Centre for Telematics and Information Technology (CTIT)

In this paper, we formulate the theory of nonlinear elasticity in a geometrically intrinsic manner using exterior calculus and bundle-valued differential forms. We represent kinematics variables, such as velocity and rate of strain, as intensive vector-valued forms, while kinetics variables, such as stress and momentum, as extensive covector-valued...

One in eight females will be diagnosed with breast cancer in their lifetime, making it the most diagnosed cancer globally [1]. Three phases are essential for the outcome of breast cancer; early detection, accurate diag- nosis and treatment. Magnetic resonance imaging (MRI) has proven to be highly sensitive in detecting possible tu- mors lesions com...

Over 570,000 new cases of bladder cancer are diagnosed worldwide every year[1]. It is essential to detect new tumors as early as possible to reduce the mortality rate. In addition, the muscle invasiveness of lesions should be quantified to determine the optimal treatment plan. Within the ”Next-gen in-vivo cancer diagnostics” re- search project we p...

It is well known that conservative mechanical systems exhibit local oscillatory behaviors due to their elastic and gravitational potentials, which completely characterize these periodic motions together with the inertial properties of the system. The classification of these periodic behaviors and their geometric characterization are in an ongoing s...

This work demonstrates in-situ monitoring of additive manufacturing through Fused Filament Fabrication with multi-electrode resistance measurements as an alternative to thermal and optical monitoring methods. Measurements are performed through the means of a resistive filament in combination with multiplexed nozzle to bed electrodes. When printing...

This paper investigates self-sensing properties of continuous carbon fiber reinforced, 3D-printed beams as function of the number of reinforced perimeters. Samples containing various numbers of reinforced perimeters are tested for their stiffness and strain-dependent resistance using three-point bending tests. The mechanical properties are modelled...

Purpose Abnormalities in the bladder wall require careful investigation regarding type, spatial position and invasiveness. Construction of a 3-D model of the bladder is helpful to ensure adequate coverage of the scanning procedure, quantitative comparison of bladder wall textures between successive sessions and finding back previously discovered ab...

In this paper we formulate the theory of nonlinear elasticity in a geometrically intrinsic manner using exterior calculus and bundle-valued differential forms. We represent kinematics variables, such as velocity and rate-of-strain, as intensive vector-valued forms while kinetics variables, such as stress and momentum, as extensive covector-valued p...

p>Patients with hemiplegia are usually restricted to performing general bilateral activities of daily life (gbADLs). Bilateral training has been verified to contribute to the rehabilitation of physical functions. Although robotic systems are gradually being employed in the field of rehabilitation, few studies have performed simulations with regards...

p>Patients with hemiplegia are usually restricted to performing general bilateral activities of daily life (gbADLs). Bilateral training has been verified to contribute to the rehabilitation of physical functions. Although robotic systems are gradually being employed in the field of rehabilitation, few studies have performed simulations with regards...

In this contribution, we extend the hybridization framework for the Hodge Laplacian (Awanou et al., Hybridization and postprocessing in finite element exterior calculus, 2023) to port-Hamiltonian systems. To this aim, a general dual field continuous Galerkin discretization is introduced, in which one variable is approximated via conforming finite e...

p>Patients with hemiplegia are usually restricted to performing general bilateral activities of daily life (gbADLs). Bilateral training has been verified to contribute to the rehabilitation of physical functions. Although robotic systems are gradually being employed in the field of rehabilitation, few studies have performed simulations with regards...

Within a robotic context, we merge the techniques of passivity-based control (PBC) and reinforcement learning (RL) with the goal of eliminating some of their reciprocal weaknesses, as well as inducing novel promising features in the resulting framework. We frame our contribution in a scenario where PBC is implemented by means of virtual energy tank...

In this document we describe and discuss energy tanks, a control algorithm which has gained popularity inside the robotics and control community over the last years. This article has the threefold scope of i) introducing to the reader the topic in a simple yet precise way, starting with a throughout description of the energy-aware framework, where...

It is well known that conservative mechanical systems exhibit local oscillatory behaviours due to their elastic and gravitational potentials, which completely characterise these periodic motions together with the inertial properties of the system. The classification of these periodic behaviours and their geometric characterisation are in an on-goin...

This work addresses the interaction control problem of a fully actuated aerial vehicle considered as a flying end-effector. We tackle the problem using geometrically consistent variable-stiffness impedance control for safe wrench regulation using the concept of energy tanks, where both the modeling and the control are carried out in the port Hamilt...

In this paper we propose a novel approach to discretize linear port-Hamiltonian systems while preserving the underlying structure. We present a finite element exterior calculus formulation that is able to mimetically represent conservation laws and cope with mixed open boundary conditions using a single computational mesh. The possibility of includ...

In this document we describe and discuss energy tanks, a control algorithm which has gained popularity inside the robotics and control community over the last years. This article has the threefold scope of i) introducing to the reader the topic in a simple yet precise way, starting with a throughout description of the energy-aware framework, where...

Humans are capable of managing multiple tasks simultaneously. It is widely assumed that human motor control can be emulated by impedance control. To achieve human-like behavior, however, the impedance parameters of multiple tasks may vary during task execution. We propose an algorithm that shapes task impedance as a function of the robot’s time-var...

A description of thermodynamics for continuum mechanical systems is presented in the coordinate-free language of exterior calculus. First, a careful description of the mathematical tools that are needed to formulate the relevant conservation laws is given. Second, following an axiomatic approach, the two thermodynamic principles will be described,...

A description of thermodynamics for continuum mechanical systems is presented in the coordinate-free language of differential geometry. First, a careful description of the mathematical tools that are needed to formulate the relevant conservation laws is given. Second, following an axiomatic approach, the two thermodynamic principles will be describ...

The Robird is a bird-like drone or ornithopter that generates both lift and thrust by flapping its wings. Its appearance, size and weight, but specifically its flapping flight performance resemble that of a Peregrine falcon. This paper describes an extension of Prandtl's Lifting-line method from steady flow to unsteady flow to predict the unsteady...

In this article, we present a novel energy-based control architecture on Euler-Bernoulli beams equipped with a variable stiffness mechanism. To proof the methodological validity of the approach, two control laws are developed using the power balance of the system, explicitly encoded in its infinite-dimensional port-Hamiltonian formulation. The laws...

View Video Presentation: https://doi.org/10.2514/6.2022-3447.vid The Robird is a bird-like drone classified as an ornithopter that flies by flapping the wings. Its unique design features make it resemble a Peregrine falcon in size and weight, in addition to the flapping flight performance. This paper proposes the application of Prandtl’s unsteady L...

Coronavirus disease 2019 (COVID-19) has affected the conditions of work in healthcare institutions and the quality of patient care around the world. Emerging healthcare robotic technology may facilitate and improve the overall quality of life, as well as the diagnostics, rehabilitation, and intervention services. This paper reports the lessons lear...

Inspection and maintenance are two crucial aspects of industrial pipeline plants. While robotics has made tremendous progress in the mechanic design of in-pipe inspection robots, the autonomous control of such robots is still a big open challenge due to the high number of actuators and the complex manoeuvres required. To address this problem, we in...

In this paper we propose a novel approach to discretize linear port-Hamiltonian systems while preserving the underlying structure. We present a finite element exterior calculus formulation that is able to mimetically represent conservation laws and cope with mixed open boundary conditions using a single computational mesh. The possibility of includ...

We introduce the geometric structure underlying the port-Hamiltonian models for distributed parameter systems exhibiting moving material domains. The first part of the paper aims at introducing the differential geometric tools needed to represent infinite-dimensional systems on time–varying spatial domains in a port–based framework. A throughout de...

A geometric dynamic modeling framework for generic multirotor aerial vehicles (MAV), based on a modern Lie group formulation of classical screw theory, is presented. Our framework allows for a broad range of rotor-wing configurations: any number of rotors can be attached in arbitrary configurations to either the body or wings, with the rotors and w...

A biopsy is the only diagnostic procedure for accurate histological confirmation of breast cancer. When sonographic placement is not feasible, a Magnetic Resonance Imaging(MRI)-guided biopsy is often preferred. The lack of real-time imaging information and the deformations of the breast make it challenging to bring the needle precisely towards the...

We introduce the geometric structure underlying the port-Hamiltonian models for distributed parameter systems exhibiting moving material domains.

Pneumatic stepper motors can be used to actuate MR safe robotics and other devices. Due to tight space requirements inside the MRI scanner, it is useful to combine several individual stepper motors into a single device with an efficient shared actuator mechanism, called the multiple concentric shaft pneumatic stepper motor. The demonstrated “multim...

Aerial physical interaction is a promising field for unmanned aerial vehicles in future applications. This paper presents a novel paradigm for automatic aerial contact-based sliding interaction (inspection/cleaning) tasks in aerial robotics allowing a 3D force with a constant norm to be applied on generic surfaces with unknown geometry. The interac...

Multi-axis stepper motors offer a compact solution to actuate multiple degrees of freedom in a mechanical system by a single device. This research presents an electric stepper motor with three coaxial shafts driven by a single stator. The motor dimensions are 42 × 42 × 44 mm $^3$ (excluding output shafts), its mass is 0.326 kg and it includes thre...

Inspection and maintenance are two crucial aspects of industrial pipeline plants. While robotics has made tremendous progress in the mechanic design of in-pipe inspection robots, the autonomous control of such robots is still a big open challenge due to the high number of actuators and the complex manoeuvres required. To address this problem, we in...

Autonomous robots require high degrees of cognitive and motoric intelligence to come into our everyday life. In non-structured environments and in the presence of uncertainties, such degrees of intelligence are not easy to obtain. Reinforcement learning algorithms have proven to be capable of solving complicated robotics tasks in an end-to-end fash...

A biopsy is the only diagnostic procedure for accurate histological confirmation of breast cancer. When sonographic placement is not feasible, a Magnetic Resonance Imaging(MRI)-guided biopsy is often preferred. The lack of real-time imaging information and the deformations of the breast make it challenging to bring the needle precisely towards the...

This paper introduces the fabrication and characterization of a soft, 3D-printed, resistive cantilever flow sensor, inspired by nature. The sensor has a wider end, to increase drag, and a thin bending section with differential resistive strain gauges. Wind tunnel tests show the operation of the sensor. The relation between tip displacement and resi...

3D-printing conductive structures have recently been receiving increased attention, especially in the field of 3D-printed sensors. However, the printing processes introduce anisotropic electrical properties due to the infill and bonding conditions. Insights into the electrical conduction that results from the anisotropic electrical properties are c...

In this work we consider the current certification process of applications with physical human-robot interaction (pHRI). Two major hazards are collisions and clamping scenarios. The implementation of safety measures in pHRI applications typically depends strongly on coordinates, e.g., to monitor the robot velocity or to predict external forces. We...

In this work we consider the current certification process of applications with physical human–robot interaction (pHRI). Two major hazards are collisions and clamping scenarios. The implementation of safety measures in pHRI applications typically depends strongly on coordinates, e.g., to monitor the robot velocity or to predict external forces. We...

In this work we consider the current certification process of applications with physical human-robot interaction (pHRI). Two major hazards are collisions and clamping scenarios. The implementation of safety measures in pHRI applications typically depends strongly on coordinates, e.g., to monitor the robot velocity or to predict external forces. We...

In this work we consider the current certification process of applications with physical human-robot interaction (pHRI). Two major hazards are collisions and clamping scenarios. The implementation of safety measures in pHRI applications typically depends strongly on coordinates, e.g., to monitor the robot velocity or to predict external forces. We...

In this work we consider the current certification process of applications with physical human–robot interaction (pHRI). Two major hazards are collisions and clamping scenarios. The implementation of safety measures in pHRI applications typically depends strongly on coordinates, e.g., to monitor the robot velocity or to predict external forces. We...

A geometric dynamic modeling framework for generic multirotor aerial vehicles (MAV), based on a modern Lie group formulation of classical screw theory, is presented. Our framework allows for a broad range of rotor-wing con gurations: any number of rotors can be attached in arbitrary con gurations to either the body or wings, with the rotors and win...

A port-Hamiltonian model for compressible Newtonian fluid dynamics is presented in entirely coordinate-independent geometric fashion. This is achieved by the use of tensor-valued differential forms that allow us to describe the interconnection of the power preserving structure which underlies the motion of perfect fluids to a dissipative port which...

A port-Hamiltonian model for compressible Newtonian fluid dynamics is presented in entirely coordinate-independent geometric fashion. This is achieved by use of tensor-valued differential forms that allow to describe describe the interconnection of the power preserving structure which underlies the motion of perfect fluids to a dissipative port whi...

In this two-parts paper, we present a systematic procedure to extend the known Hamiltonian model of ideal inviscid fluid flow on Riemannian manifolds in terms of Lie-Poisson structures to a port-Hamiltonian model in terms of Stokes-Dirac structures. The first novelty of the presented model is the inclusion of non-zero energy exchange through, and w...

Part I of this paper presented a systematic derivation of the Stokes Dirac structure underlying the port-Hamiltonian model of ideal fluid flow on Riemannian manifolds. Starting from the group of diffeomorphisms as a configuration space for the fluid, the Stokes Dirac structure is derived by Poisson reduction and then augmented by boundary ports and...

For the study of highly nonlinear, conservative dynamic systems, finding special periodic solutions which can be seen as generalization of the well-known normal modes of linear systems is very attractive. However, the study of low-dimensional invariant manifolds in the form of nonlinear normal modes is rather a niche topic, treated mainly in the co...

Purpose of the review Robotics is a rapidly advancing field, and its introduction in healthcare can have a multitude of benefits for clinical practice. Especially, applications depending on the radiologist’s accuracy and precision, such as percutaneous interventions, may profit. This paper provides an overview of recent robot-assisted percutaneous...

The use of robotics in health care has seen a recent rise in interest due to its potential for use during the SARS-CoV-2 pandemic. The transmission rate of COVID-19 has meant that health-care workers are under increasing pressure, risks, and workload to manage the requirements of personal protective equipment, strict disinfection procedures, and th...

In this paper we envision how to tackle a particularly challenging problem which presents highly interdisciplinary features, ranging from biology to engineering: the dynamic description and technological realisation of flapping flight. This document explains why, in order to gain new insights into this topic, we chose to employ port-Hamiltonian the...

A port-Hamiltonian formulation of von Kármán beams is presented. The variables selection lead to a non linear interconnection operator, while the constitutive laws are linear. The model can be readily discretized by exploiting a coenergy formulation and a mixed finite element method. The mixed formulation does not demand the H² regularity requireme...

In this paper we address the modeling of incompressible Navier-Stokes equations in the port-Hamiltonian framework. Such model not only allows describing the energy dissipation due to viscous effects but also incorporates the non-zero energy exchange through the boundary of the spatial domain for generic boundary conditions. We present in this work...

This paper introduces a characterization technique to study 3D-printing of conductors and sensors during fabrication. Currently characterization of 3D-printed sensors is done after fabrication. In our novel method, however, the electrical resistance is monitored in-situ by electrically contacting the part in the beginning of the print process. This...

Biopsy of breast lesions only visible on MRI may benefit from patient-specific finite-element modeling of the breast. This requires acquisition of the heterogeneous elasticity distribution. An acoustically transparent pad has been developed which enables strain elastography imaging using ultrasound without need for additional force or pressure sens...

Part I of this paper presented a systematic derivation of the Stokes Dirac structure underlying the port-Hamiltonian model of ideal fluid flow on Riemannian manifolds. Starting from the group of diffeomorphisms as a configuration space for the fluid, the Stokes Dirac structure is derived by Poisson reduction and then augmented by boundary ports and...