Paolo Paoletti

Paolo Paoletti
University of Liverpool | UoL · School of Engineering

PhD

About

63
Publications
7,736
Reads
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453
Citations
Additional affiliations
October 2017 - present
University of Liverpool
Position
  • Professor (Associate)
October 2012 - present
University of Liverpool
Position
  • Lecturer
September 2012 - October 2012
Education
January 2007 - December 2009
University of Florence
Field of study
  • Nonlinear dynamics and complex systems
September 2004 - July 2006
University of Florence
Field of study
  • Automation engineering
September 2001 - July 2004
University of Florence
Field of study
  • Electronic engineering

Publications

Publications (63)
Article
This paper aims to elucidate the application of feedback linearization in systems having nonsmooth nonlinearities. With the aid of analytical expressions originating from classical feedback linearization theory, it is demonstrated that for a subset of nonsmooth systems, ubiquitous in the structural dynamics and vibrations community, the theory hold...
Article
Full-text available
The interaction of a robotic manipulatorwith unknown soft objects represents a significant challenge for traditional robotic platforms because of the difficulty in controlling the grasping force between a soft object and a stiff manipulator. Soft robotic actuators inspired by elephant trunks, octopus limbs and muscular hydrostats are suggestive of...
Article
Full-text available
While Laser powder bed fusion (L-PBF) machines have greatly improved in recent years, the L-PBF process is still susceptible to several types of defect formation. Among the monitoring methods that have been explored to detect these defects, camera-based systems are the most prevalent. However, using only photodiode measurements to monitor the build...
Preprint
Full-text available
Most current works in Sim2Real learning for robotic manipulation tasks leverage camera vision that may be significantly occluded by robot hands during the manipulation. Tactile sensing offers complementary information to vision and can compensate for the information loss caused by the occlusion. However, the use of tactile sensing is restricted in...
Article
Full-text available
A microcantilever is a suspended micro-scale beam structure supported at one end which can bend and/or vibrate when subjected to a load. Microcantilevers are one of the most fundamental miniaturized devices used in microelectromechanical systems and are ubiquitous in sensing, imaging, time reference, and biological/ biomedical applications. They ar...
Preprint
Full-text available
Sleep posture is linked to several health conditions such as nocturnal cramps and more serious musculoskeletal issues. However, in-clinic sleep assessments are often limited to vital signs (e.g. brain waves). Wearable sensors with embedded inertial measurement units have been used for sleep posture classification; nonetheless, previous works consid...
Article
Full-text available
In this article, a self-reconfiguring OrigamiSat concept is presented. The reconfiguration of the proposed OrigamiSat is triggered by combining the effect of 4D material (i.e. origami’s edges) and changes in the local surface optical properties (i.e., origami’s facets) to harness the solar radiation pressure acceleration. The proposed OrigamiSat us...
Preprint
Full-text available
Prestrained elastic networks arise in a number of biological and technological systems ranging from the cytoskeleton of cells to tensegrity structures. To understand the response of such a network as a function of the prestrain, we consider a minimal model in one dimension. We do this by considering a chain (1D network) of elastic springs upon whic...
Article
Full-text available
The human foot is uniquely adapted to bipedal locomotion and has a deformable arch of variable stiffness. Intrinsic foot muscles regulate arch deformation, making them important for foot function. In this study we explore the hypothesis that normal daily activity in minimal footwear, which provides little or no support, increases foot muscle streng...
Article
Full-text available
A self-oscillating microcantilever in a feedback loop comprised of a gain, a saturator, and an adjustable phase-shifter is used to measure the viscosity of Newtonian fluids. Shifting the signal of the loop with the adjustable phase-shifter causes sudden jumps in the oscillation frequency of the cantilever. The exact position of these jumps depends...
Article
Most current works in Sim2Real learning for robotic manipulation tasks leverage camera vision that may be significantly occluded by robot hands during the manipulation. Tactile sensing offers complementary information to vision and can compensate for the information loss caused by the occlusion. However, the use of tactile sensing is restricted in...
Chapter
Recent studies on sleep reveal its impact on the well-being of humans. Monitoring of in-bed body postures can provide clinicians with early indicators of a wide range of musculoskeletal disorders. Current work on sleep pose classification is directed at non-wearable technologies, with issues associated to limited body observability and concerns ove...
Chapter
This paper presents the design of an end-effector for handling of supplies commonly found in chemistry labs. The system uses a cable loop capable of providing an effective grasp of any prismatic or cylindrical object, making it ideal for handling vials and other containers commonly used in laboratories. When compared to the more common parallel jaw...
Conference Paper
Full-text available
A simplified model for predicting behaviour of soft actuators and support the development of an automatic design tool is proposed in this paper. In particular, the model aims to predict curvature and tip force of inflated soft pneumatic actuators (SPAs) using computationally inexpensive models. Experimental validation shows that the proposed models...
Article
Dynamic substructuring is a popular hybrid testing technique that mixes physical testing with numerical simulations. Research in this domain has mainly focused so far on structures and decomposition strategies that result in asymptotically stable systems. However, several cases fall outside this family, with either the physical or the numerical par...
Conference Paper
Full-text available
This paper presents the design of an end-effector for handling of supplies commonly found in chemistry labs. The system uses a cable loop capable of providing an effective grasp of any prismatic or cylindrical object, making it ideal for handling vials and other containers commonly used in laboratories. When compared to the more common parallel jaw...
Preprint
Full-text available
This study evaluates whether a combination of photodiode sensor measurements, taken during laser powder bed fusion (L-PBF) builds, can be used to predict the resulting build quality via a purely data-based approach. We analyse the relationship between build density and features that are extracted from sensor data collected from three different photo...
Conference Paper
Full-text available
This paper presents a low-cost localisation system based on ultrasonic sensing and time of flight measurements. A compact ultrasound emitter has been designed to generate omnidirectional trains of ultrasound pulses which are then picked up by several fixed receivers measuring time difference of arrival. A least squares approach is used to analytica...
Conference Paper
Full-text available
One of the most difficult challenges faced by ground robots operating in the aftermath of a disaster is the presence of uneven and unstable terrains; in these environments traditional locomotive systems struggle. In this work, a Polyurethane Foam depositing system is proposed to enable ground robots to overcome obstacles and navigate challenging su...
Chapter
Full-text available
One of the most difficult challenges for terrestrial robotic platforms in disaster scenarios is their inability to traverse highly irregular terrain. Many different robotic architectures have been proposed over recent years, each with benefits and shortfalls. In this work, we propose a Polyurethane Foam depositing system, which can be applied to an...
Article
Full-text available
Risk-averse areas such as the medical, aerospace and energy sectors have been somewhat slow towards accepting and applying Additive Manufacturing (AM) in many of their value chains. This is partly because there are still significant uncertainties concerning the quality of AM builds. This paper introduces a machine learning algorithm for the automat...
Article
Full-text available
Using the atomic force microscopy- (AFM-) PeakForce quantitative nanomechanical mapping (QNM) technique, we have previously shown that the adventitia of the human internal mammary artery (IMA), tested under dehydrated conditions, is altered in patients with a high degree of arterial stiffening. In this study, we explored the nanoscale elastic modul...
Preprint
Full-text available
Risk-averse areas such as the medical, aerospace and energy sectors have been somewhat slow towards accepting and applying Additive Manufacturing (AM) in many of their value chains. This is partly because there are still significant uncertainties concerning the quality of AM builds. This paper introduces a machine learning algorithm for the automat...
Article
Full-text available
A versatile mass-sensing platform based on the nonlinear dynamical response of a microcantilever embedded in a self-excitation feedback loop is proposed. It is experimentally shown that the delay imposed in the feedback loop by an adjustable phase-shifter can be used to finely tune this system to work in three different modalities, according to the...
Article
Full-text available
Statement of significance: Arterial stiffening occurs as part of the natural aging process and is strongly linked to cardiovascular risk. Although arterial stiffening is routinely measured in vivo, little is known about how localised changes in artery structure and biomechanics contributes to in vivo arterial stiffening. This study focusses on the...
Article
Full-text available
A viscosity sensor based on the nonlinear behaviour of a microcantilever embedded in a self-excitation loop with an adjustable phase-shifter is proposed. The self-sustained oscillation frequencies of the cantilever are experimentally and theoretically investigated as functions of the fluid viscosity and of the imposed phase shift of the signal alon...
Conference Paper
Arterial stiffening is well-established as a powerful predictor of cardiovascular diseases. However, arterial stiffening is rarely associated with extracellular matrix changes in arterial tissue. In this study, we present localized nanomechanical properties in the human internal mammary artery (IMA) along with collagen fibril morphology in patients...
Article
Full-text available
Microcantilevers are increasingly being used to create sensitive sensors for rheology and mass sensing at the micro- and nano-scale. When operating in viscous liquids, the low quality factor of such resonant structures, translating to poor signal-to-noise ratio, is often manipulated by exploiting feedback strategies. However, the presence of feedba...
Conference Paper
Aeroelastic instabilities due to the interaction between airflow and wings have long constrained the flight envelope of many types of aircrafts. A typical example of these phenomena is fluttering, a self-sustained oscillation in pitch, plunge or flap angle. Control systems and accurate models are then required to describe and suppress this undesire...
Article
Full-text available
Large networks of interacting dynamical systems are well-known for the complex behaviours they are able to display, even when each node features a quite simple dynamics. Despite examples of such networks being widespread both in nature and in technological applications, the interplay between the local and the macroscopic behaviour, through the inte...
Conference Paper
Control of nonlinear systems with uncertain information about the nonlinearity poses significant challenges, as any mismatch between the true nonlinearity and the one assumed for controller design can result in performance degradation or even instability. In this paper we merge optimal nonlinearity approximations with controller dissipativity prope...
Conference Paper
The paper introduces a novel platooning model for vehicles subject to nonlinear drag. A linear parametric controller, taking into account both the actual position and the relative displacement with respect to neighbors, is applied to each vehicle and, then, its effects are investigated via a semi-analytical approach based on partial differential eq...
Article
Full-text available
When dealing with linear systems feedback interconnected with memoryless nonlinearities, a natural control strategy is making the overall dynamics linear at first and then designing a linear controller for the remaining linear dynamics. By canceling the original nonlinearity via a first feedback loop, global linearization can be achieved. However,...
Article
Full-text available
Systems composed by a linear dynamical part feedback interconnected with a static nonlinearity are traditionally controlled by canceling the nonlinearity through a first feedback loop, and then designing a linear controller for the remaining linear dynamics. However, this procedure may provide unsatisfactory performance, and even lead to instabilit...
Article
Full-text available
The locomotion of many soft-bodied animals is driven by the propagation of rhythmic waves of contraction and extension along the body. These waves are classically attributed to globally synchronized periodic patterns in the nervous system embodied in a central pattern generator (CPG). However, in many primitive organisms such as earthworms and inse...
Article
Full-text available
Feedback linearisation is a well-known technique in the controls community but has not been widely taken up in the vibrations community. It has the advantage of linearising nonlinear system models, thereby enabling the avoidance of the complicated mathematics associated with nonlinear problems. A particular and common class of problems is considere...
Conference Paper
Full-text available
A natural way of controlling linear systems feedback interconnected with memoryless nonlinearities is canceling this latter with a first feedback loop, and then designing a linear controller for the remaining linear dynamics. Nevertheless, this procedure may provide unsatisfactory performance, and even lead to instability, when the nonlinearity can...
Article
Full-text available
Birds, fish and other animals routinely use unsteady effects to save energy by alternating between phases of active propulsio and passive coasting. Here, we construct a minimal model for such behaviour that can be couched as an optimal control proble via an analogy to travelling with a rechargeable battery. An analytical solution of the optimal con...
Article
Full-text available
We apply the PeakForce Quantitative Nanomechanical Property Mapping (PFQNM) atomic force microscopy mode for the investigation of regional variations in the nanomechanical properties of porcine sclera. We examine variations in the collagen fibril diameter, adhesion, elastic modulus and dissipation in the posterior, equatorial and anterior regions o...
Conference Paper
Full-text available
Networks of dynamical systems are widespread both in nature and in technology applications, but the interplay between the node dynamics, their interconnections and the macroscopic behavior is still not completely understood. In fact, the intrinsically large dimension of the phase space of such networks represents the main obstacle for their analysi...
Conference Paper
Dynamic mode atomic force microscopy provides high resolution in imaging biological samples, but it features a reduced scanning velocity. In this paper we investigate a recent scheme in which the cantilever gets excited by a feedback loop containing a saturation function. The proposed modality is then analyzed via Floquet theory and compared to the...
Article
Traditional dynamic modalities for atomic force microscopy imaging suffer from a stringent trade-off between fast scanning speed, weak interaction forces and accurate topography reconstruction. Finding an effective compromise between these aspects is often challenging, especially for soft biological samples for which stringent requirements hold whe...
Article
Although it is a common practice in the field of Dynamics to treat a system as being linear, the assumption of linearity is only valid in situations where the effect of any nonlinearities is minimal. Significant nonlinear behaviour (such as Limit Cycle Oscillations) has been observed in many practical manifestations of aeroelastic systems, highligh...
Article
Full-text available
Balancing on a tightrope or a slackline is an example of a neuromechanical task where the whole body both drives and responds to the dynamics of the external environment, often on multiple timescales. Motivated by a range of neurophysiological observations, here we formulate a minimal model for this system and use optimal control theory to design a...
Article
A framework for modeling acceleration waves propagation in complex materials is presented. Coupled propagation of elasto-acoustic, microstructural and thermal waves is investigated in the full three dimensional case. The presence of microstructure inside each material element is taken into account without introducing additional hypotheses on the ph...
Article
Full-text available
Controlled gliding during descent has been thought of as a crucial intermediate step toward the evolution of powered flight in a variety of animals. Here we develop and analyse a model for the controlled descent of thin bodies in quiescent fluids. Focusing on motion in two dimensions for simplicity, we formulate the question of steering an elliptic...
Article
Full-text available
The use of a laser to induce oscillations of an atomic force microscopy cantilever provides a way to excite the dynamics of the system in a very controlled manner. This excitation scheme has been used to obtain reliable self-sustained oscillations, in air and in liquid environments, and to implement an additional control loop leading to a soft, low...
Conference Paper
Full-text available
Propagation of traveling waves along one dimensional networks of identical dynamical systems is analysed by suitably defining a family of ordinary differential equations (ODEs) that describes the traveling wave itself. An ODE of reduced order is derived for computing reference solutions, which are then exploited to prove via implicit function theor...
Article
Full-text available
The need for investigating the properties of new materials at nanoscale level continuously pushes the development of higher resolution measurement instruments. In this context, a promising dynamic atomic force microscopy setup, where the cantilever gets excited by a nonlinear feedback loop, has been recently introduced. In the first part of the pap...
Conference Paper
Conditions for traveling wave propagation in networks of dynamical systems are investigated by suitably defining a family of ordinary differential equations (ODEs) whose solutions approximate the wave itself with increasing degree of accuracy. A reduced order ODE is considered for computing reference solutions, which are then exploited to prove via...
Article
Full-text available
The mechanics of complex bodies with memory effects is discussed in linearized setting. The attention is focused on the characterization of free energies in terms of minimum work and maximum recoverable work in the bulk and along a discontinuity surface endowed with its own surface energy, a surface internal to the body. To this aim, use is made of...
Conference Paper
Full-text available
The paper presents a new atomic force microscopy setup where the cantilever gets excited by a positive feedback loop containing a saturation function. The proposed scheme can be easily modeled and analyzed in the frequency domain using harmonic balance techniques. In imaging applications, we show that an additional controller for the saturation thr...
Article
Full-text available
Tapping mode atomic force microscopy provides good resolution in imaging applications, but it still requires a time-consuming initial configuration and features quite low scanning velocity. In this paper we present a new dynamic mode in which the cantilever gets excited by a feedback loop containing a saturation function. The proposed scheme is the...
Article
In this letter, we provide evidence that the vibrating resonance frequency of an uncalibrated atomic force microscope cantilever can be precisely related to the viscosity of the fluid in which it is immersed, independent of any knowledge of the cantilever's geometry and spring constant. Reverse geometry, density, and spring constants of a cantileve...

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