
Stefano StramigioliUniversity of Twente | UT · Centre for Telematics and Information Technology (CTIT)
Stefano Stramigioli
M.Sc. cum laude, University of Bologna, Ph.D. cum laude, Delft University of Technology
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Publications (458)
In this paper, we present a novel approach to the geometric formulation of solid and fluid mechanics within the port-Hamiltonian framework, which extends the standard Hamiltonian formulation to non-conservative and open dynamical systems. Leveraging Dirac structures, instead of symplectic or Poisson structures, this formalism allows the incorporati...
In this contribution, a finite element scheme to impose mixed boundary conditions without introducing Lagrange multipliers is presented for wave propagation phenomena described as port-Hamiltonian systems. The strategy relies on finite element exterior calculus and a domain decomposition to interconnect two systems with different causalities. The s...
A-mode ultrasound has not been widely used in medical applications compared to B-mode ultrasound. The primary reason is that the data representation, being 1-dimensional (1D), is less intuitive for users and harder to interpret. However, A-mode ultrasound has several advantageous features, such as faster data acquisition for real-time sensing, dire...
In this letter, we propose a control scheme for rigid bodies designed to optimise transient behaviors. The search space for the optimal control input is parameterized to yield a passive, specifically lossless, nonlinear feedback controller. As a result, it can be combined with other stabilizing controllers without compromising the stability of the...
Using a port-Hamiltonian formalism, we show the qualitative and quantitative effect of safety-critical control implemented with control barrier functions (CBFs) on the power balance of controlled physical systems. The presented results will provide novel tools to design CBFs inducing desired energetic behaviors of the closed-loop system, including...
This work presents a novel approach for the optimization of dynamic systems on finite-dimensional Lie groups. We rephrase dynamic systems as so-called neural ordinary differential equations (neural ODEs), and formulate the optimization problem on Lie groups. A gradient descent optimization algorithm is presented to tackle the optimization numerical...
Fused filament fabrication is a popular fabrication technique. Currently there is a need for in-situ monitoring modalities to gather real-time information on prints, both for quality control and closed-loop control. Despite current advancements, effective and affordable in-situ monitoring techniques for non-destructive defect detection of voids and...
Fused Filament Fabrication is a popular fabrication technique. Currently there is a need for in-situ monitoring modalities to gather real-time information on prints, both for quality control and closed-loop control. Despite current advancements, effective and affordable in-situ monitoring techniques for non-destructive defect detection of voids and...
Within a robotic context, the techniques of passivity‐based control and reinforcement learning are merged with the goal of eliminating some of their reciprocal weaknesses, as well as inducing novel promising features in the resulting framework. The contribution is framed in a scenario where passivity‐based control is implemented by means of virtual...
DC Electric metamaterials are interesting for electronics, sensors and actuators by enabling steering of current. In this paper we realize such DC electric metamaterials with Fused Filament Fabrication by tuning the nozzle temperature, bed temperature and extrusion width to achieve anisotropic electrical conduction. Both temperatures influence the...
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...
We present the design and development of a non-linear series-elastic element based on repelling magnets. Progressive stiffness offers the transparency advantages of a low-stiffness elastic actuator at low load levels, and the high torque tracking bandwidth of a high-stiffness actuator at high loads. The design space of this magnet-based concept is...
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...