The integration of energy harvesting systems into sensing technologies can result in novel autono... more The integration of energy harvesting systems into sensing technologies can result in novel autonomous sensor nodes, characterized by significant simplification and mass reduction. The use of piezoelectric energy harvesters (PEHs), particularly in cantilever form, is considered as one of the most promising approaches aimed at collecting ubiquitous low-level kinetic energy. Due to the random nature of most excitation environments, the narrow PEH operating frequency bandwidth implies, however, the need to introduce frequency up-conversion mechanisms, able to convert random excitation into the oscillation of the cantilever at its eigenfrequency. A first systematic study is performed in this work to investigate the effects of 3D-printed plectrum designs on the specific power outputs obtainable from FUC excited PEHs. Therefore, novel rotating plectra configurations with different design parameters, determined by using a design-of-experiment methodology and manufactured via fused depositio...
The development of wearable devices and remote sensor networks progressively relies on their incr... more The development of wearable devices and remote sensor networks progressively relies on their increased power autonomy, which can be further expanded by replacing conventional power sources, characterized by limited lifetimes, with energy harvesting systems. Due to its pervasiveness, kinetic energy is considered as one of the most promising energy forms, especially when combined with the simple and scalable piezoelectric approach. The integration of piezoelectric energy harvesters, generally in the form of bimorph cantilevers, with wearable and remote sensors, highlighted a drawback of such a configuration, i.e., their narrow operating bandwidth. In order to overcome this disadvantage while maximizing power outputs, optimized cantilever geometries, developed using the design of experiments approach, are analysed and combined in this work with frequency up-conversion excitation that allows converting random kinetic ambient motion into a periodical excitation of the harvester. The deve...
A finite element model (FEM) analysis of the coupled electromechanical behaviour of bimorph piezo... more A finite element model (FEM) analysis of the coupled electromechanical behaviour of bimorph piezoelectric energy scavengers with varying element types and mesh densities is performed in this work. At first a 3D modal analysis is undertaken to validate the eigenfrequencies and eigenmodes obtained via the uncoupled analytical modal model. A harmonic dynamic analysis is performed next so as to evaluate the voltage output of the system under dynamic loading. Finally, a full transient analysis is done. The validity of the results is enhanced by varying the applied resistive loads.
A three V-groove (Maxwell-type) kinematic mount design configuration constrains all degrees of fr... more A three V-groove (Maxwell-type) kinematic mount design configuration constrains all degrees of freedom of the apparatus mounted onto it, thus allowing its high-precision positioning and re-positioning. The analysis of this mechanical assembly comprises force and moment balances, as well as expressions for stress-strain and error motion calculations. For determined loading conditions and the geometry of the mount, the resulting loads across each groove-ball interface imply, however, the necessity to consider the complex nonlinear Hertz theory of point contacts between elastically deforming solids. The available analytical approaches to the calculation of the conditions at the ball-V groove contacts are hence recalled in this work with the aim of establishing the respective limits of applicability. The obtained results are validated experimentally. A structured calculation procedure is then used to assess the stability of a kinematic mount employed to support a large mechanical compon...
The nonlinear model of a small-scale ultra-high precision positioning device is developed in this... more The nonlinear model of a small-scale ultra-high precision positioning device is developed in this work in the MATLAB/SIMULINK environment. The conventional Stribeck model is used to describe the DC motor frictional nonlinearities, while the more sophisticated Dahl model is used for the behaviour of the mechanical components of the system. In the experimental set-up, a linear incremental encoder is used as a feedback sensor, while a laser interferometric system is employed to validate the obtained precision. The digital PID controller is implemented on the FPGA architecture by using the LabVIEW programming environment. A good matching of simulated and measured dynamic responses is obtained although some friction-induced discrepancies are still present. Ultra-high precision positioning, frictional nonlinear disturbances, experimental validation, FPGA architecture
An innovative mechanical design of a compliant compact slits system is presented. The system is c... more An innovative mechanical design of a compliant compact slits system is presented. The system is compatible with a high vacuum environment and characterised by a travel range of several millimetres with concurrent nanometric accuracies.
Converting vibration energy into electric energy via the piezoelectric effect is one of the most ... more Converting vibration energy into electric energy via the piezoelectric effect is one of the most prominent small-scale energy scavenging concepts aimed at powering ubiquitous wireless sensor networks. Several analytical and numerical models, which have also been experimentally validated, have been proposed in literature to characterise the behaviour of cantilever vibration energy scavengers. A finite element coupled electromechanical model of a harmonically excited multilayer energy scavenging device is developed and investigated in this work by using the ANSYS® software. The intricate design of the device is based on off-the-shelf Midé Technology® Volture energy scavengers. The results of the modal and harmonic FEM analyses are experimentally validated via a suitable set-up employing two types of cantilevers as well as several tip masses and electrical resistances. It could hence be proven that numerical analysis is a reliable tool for predicting maximum available power outputs in ...
Continuous monitoring of pollutants in watercourses requires an uninterrupted sensors’ power supp... more Continuous monitoring of pollutants in watercourses requires an uninterrupted sensors’ power supply. In the case of large networks, when sensor nodes can be placed in hardly accessible locations, energy harvesting can provide a feasible solution to assure power autonomy. The possibility to use a harvesting concept known as the piezoelectric eel is studied in this work. A custom code that implements the penalty immersed boundary method is developed and used to simulate eel’s motion. Based on the results of the calculations, eel’s design, consisting of a structural support covered with active piezoelectric polymer layers, is finalised. The respective power conditioning electronics is also been designed and prototyped. The obtained experimental results are finally given.
The behaviour of off-the-shelf commercial energy scavengers is difficult to model and to correlat... more The behaviour of off-the-shelf commercial energy scavengers is difficult to model and to correlate to the requirements of the foreseen applications due to lack of information about their electromechanical properties. Experimental set-ups are thus developed with the aim of assessing Young’s modules and optimal resistive loads. The obtained results are presented in terms of power vs. applied resistive loads.
In this work a study of the dynamic behaviour of piezoelectric vibration energy scavengers is per... more In this work a study of the dynamic behaviour of piezoelectric vibration energy scavengers is performed. The output voltages and powers are related to excitation inputs and electrical loads, permitting clear tendencies to be outlined. The coupled electromechanical behaviour shows a noteworthy hardening for increasing loads. Optimal peak powers and their dependence on system’s parameters are determined.
Dottorato di ricerca in progettazione e costruzione di macchine. 8. ciclo. A.a. 1992-95. Coordina... more Dottorato di ricerca in progettazione e costruzione di macchine. 8. ciclo. A.a. 1992-95. Coordinatore e Tutore M. M. GolaConsiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome; Biblioteca Nazionale Centrale - P.za Cavalleggeri, 1, Florence / CNR - Consiglio Nazionale delle RichercheSIGLEITItal
Friction is one of the main disturbances in precision positioning and, in the pre-sliding motion ... more Friction is one of the main disturbances in precision positioning and, in the pre-sliding motion regime, it is characterised by an elasto-plastic nonlinear hysteretic behaviour with a marked variability. Pre-sliding friction, modelled via the state-of-the-art Generalised Maxwell Slip (GMS) and the Hsieh model (HM), is experimentally assessed in this work with the aim of developing suitable control typologies aimed at compensating its effects. The models are hence compared in terms of the complexity of identifying their parameters, simulating their dynamic responses and implementing them in real-time systems. It is thus shown that the GMS model is readily identified and comprises also the sliding motion regime, whereas HM is difficult to implement and requires a separate sliding friction model with a corresponding switching function.
With the aim of increasing the efficiency of maintenance and fuel usage in airplanes, structural ... more With the aim of increasing the efficiency of maintenance and fuel usage in airplanes, structural health monitoring (SHM) of critical composite structures is increasingly expected and required. The optimized usage of this concept is subject of intensive work in the framework of the EU COST Action CA18203 “Optimising Design for Inspection” (ODIN). In this context, a thorough review of a broad range of energy harvesting (EH) technologies to be potentially used as power sources for the acoustic emission and guided wave propagation sensors of the considered SHM systems, as well as for the respective data elaboration and wireless communication modules, is provided in this work. EH devices based on the usage of kinetic energy, thermal gradients, solar radiation, airflow, and other viable energy sources, proposed so far in the literature, are thus described with a critical review of the respective specific power levels, of their potential placement on airplanes, as well as the consequently ...
The integration of energy harvesting systems into sensing technologies can result in novel autono... more The integration of energy harvesting systems into sensing technologies can result in novel autonomous sensor nodes, characterized by significant simplification and mass reduction. The use of piezoelectric energy harvesters (PEHs), particularly in cantilever form, is considered as one of the most promising approaches aimed at collecting ubiquitous low-level kinetic energy. Due to the random nature of most excitation environments, the narrow PEH operating frequency bandwidth implies, however, the need to introduce frequency up-conversion mechanisms, able to convert random excitation into the oscillation of the cantilever at its eigenfrequency. A first systematic study is performed in this work to investigate the effects of 3D-printed plectrum designs on the specific power outputs obtainable from FUC excited PEHs. Therefore, novel rotating plectra configurations with different design parameters, determined by using a design-of-experiment methodology and manufactured via fused depositio...
The development of wearable devices and remote sensor networks progressively relies on their incr... more The development of wearable devices and remote sensor networks progressively relies on their increased power autonomy, which can be further expanded by replacing conventional power sources, characterized by limited lifetimes, with energy harvesting systems. Due to its pervasiveness, kinetic energy is considered as one of the most promising energy forms, especially when combined with the simple and scalable piezoelectric approach. The integration of piezoelectric energy harvesters, generally in the form of bimorph cantilevers, with wearable and remote sensors, highlighted a drawback of such a configuration, i.e., their narrow operating bandwidth. In order to overcome this disadvantage while maximizing power outputs, optimized cantilever geometries, developed using the design of experiments approach, are analysed and combined in this work with frequency up-conversion excitation that allows converting random kinetic ambient motion into a periodical excitation of the harvester. The deve...
A finite element model (FEM) analysis of the coupled electromechanical behaviour of bimorph piezo... more A finite element model (FEM) analysis of the coupled electromechanical behaviour of bimorph piezoelectric energy scavengers with varying element types and mesh densities is performed in this work. At first a 3D modal analysis is undertaken to validate the eigenfrequencies and eigenmodes obtained via the uncoupled analytical modal model. A harmonic dynamic analysis is performed next so as to evaluate the voltage output of the system under dynamic loading. Finally, a full transient analysis is done. The validity of the results is enhanced by varying the applied resistive loads.
A three V-groove (Maxwell-type) kinematic mount design configuration constrains all degrees of fr... more A three V-groove (Maxwell-type) kinematic mount design configuration constrains all degrees of freedom of the apparatus mounted onto it, thus allowing its high-precision positioning and re-positioning. The analysis of this mechanical assembly comprises force and moment balances, as well as expressions for stress-strain and error motion calculations. For determined loading conditions and the geometry of the mount, the resulting loads across each groove-ball interface imply, however, the necessity to consider the complex nonlinear Hertz theory of point contacts between elastically deforming solids. The available analytical approaches to the calculation of the conditions at the ball-V groove contacts are hence recalled in this work with the aim of establishing the respective limits of applicability. The obtained results are validated experimentally. A structured calculation procedure is then used to assess the stability of a kinematic mount employed to support a large mechanical compon...
The nonlinear model of a small-scale ultra-high precision positioning device is developed in this... more The nonlinear model of a small-scale ultra-high precision positioning device is developed in this work in the MATLAB/SIMULINK environment. The conventional Stribeck model is used to describe the DC motor frictional nonlinearities, while the more sophisticated Dahl model is used for the behaviour of the mechanical components of the system. In the experimental set-up, a linear incremental encoder is used as a feedback sensor, while a laser interferometric system is employed to validate the obtained precision. The digital PID controller is implemented on the FPGA architecture by using the LabVIEW programming environment. A good matching of simulated and measured dynamic responses is obtained although some friction-induced discrepancies are still present. Ultra-high precision positioning, frictional nonlinear disturbances, experimental validation, FPGA architecture
An innovative mechanical design of a compliant compact slits system is presented. The system is c... more An innovative mechanical design of a compliant compact slits system is presented. The system is compatible with a high vacuum environment and characterised by a travel range of several millimetres with concurrent nanometric accuracies.
Converting vibration energy into electric energy via the piezoelectric effect is one of the most ... more Converting vibration energy into electric energy via the piezoelectric effect is one of the most prominent small-scale energy scavenging concepts aimed at powering ubiquitous wireless sensor networks. Several analytical and numerical models, which have also been experimentally validated, have been proposed in literature to characterise the behaviour of cantilever vibration energy scavengers. A finite element coupled electromechanical model of a harmonically excited multilayer energy scavenging device is developed and investigated in this work by using the ANSYS® software. The intricate design of the device is based on off-the-shelf Midé Technology® Volture energy scavengers. The results of the modal and harmonic FEM analyses are experimentally validated via a suitable set-up employing two types of cantilevers as well as several tip masses and electrical resistances. It could hence be proven that numerical analysis is a reliable tool for predicting maximum available power outputs in ...
Continuous monitoring of pollutants in watercourses requires an uninterrupted sensors’ power supp... more Continuous monitoring of pollutants in watercourses requires an uninterrupted sensors’ power supply. In the case of large networks, when sensor nodes can be placed in hardly accessible locations, energy harvesting can provide a feasible solution to assure power autonomy. The possibility to use a harvesting concept known as the piezoelectric eel is studied in this work. A custom code that implements the penalty immersed boundary method is developed and used to simulate eel’s motion. Based on the results of the calculations, eel’s design, consisting of a structural support covered with active piezoelectric polymer layers, is finalised. The respective power conditioning electronics is also been designed and prototyped. The obtained experimental results are finally given.
The behaviour of off-the-shelf commercial energy scavengers is difficult to model and to correlat... more The behaviour of off-the-shelf commercial energy scavengers is difficult to model and to correlate to the requirements of the foreseen applications due to lack of information about their electromechanical properties. Experimental set-ups are thus developed with the aim of assessing Young’s modules and optimal resistive loads. The obtained results are presented in terms of power vs. applied resistive loads.
In this work a study of the dynamic behaviour of piezoelectric vibration energy scavengers is per... more In this work a study of the dynamic behaviour of piezoelectric vibration energy scavengers is performed. The output voltages and powers are related to excitation inputs and electrical loads, permitting clear tendencies to be outlined. The coupled electromechanical behaviour shows a noteworthy hardening for increasing loads. Optimal peak powers and their dependence on system’s parameters are determined.
Dottorato di ricerca in progettazione e costruzione di macchine. 8. ciclo. A.a. 1992-95. Coordina... more Dottorato di ricerca in progettazione e costruzione di macchine. 8. ciclo. A.a. 1992-95. Coordinatore e Tutore M. M. GolaConsiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome; Biblioteca Nazionale Centrale - P.za Cavalleggeri, 1, Florence / CNR - Consiglio Nazionale delle RichercheSIGLEITItal
Friction is one of the main disturbances in precision positioning and, in the pre-sliding motion ... more Friction is one of the main disturbances in precision positioning and, in the pre-sliding motion regime, it is characterised by an elasto-plastic nonlinear hysteretic behaviour with a marked variability. Pre-sliding friction, modelled via the state-of-the-art Generalised Maxwell Slip (GMS) and the Hsieh model (HM), is experimentally assessed in this work with the aim of developing suitable control typologies aimed at compensating its effects. The models are hence compared in terms of the complexity of identifying their parameters, simulating their dynamic responses and implementing them in real-time systems. It is thus shown that the GMS model is readily identified and comprises also the sliding motion regime, whereas HM is difficult to implement and requires a separate sliding friction model with a corresponding switching function.
With the aim of increasing the efficiency of maintenance and fuel usage in airplanes, structural ... more With the aim of increasing the efficiency of maintenance and fuel usage in airplanes, structural health monitoring (SHM) of critical composite structures is increasingly expected and required. The optimized usage of this concept is subject of intensive work in the framework of the EU COST Action CA18203 “Optimising Design for Inspection” (ODIN). In this context, a thorough review of a broad range of energy harvesting (EH) technologies to be potentially used as power sources for the acoustic emission and guided wave propagation sensors of the considered SHM systems, as well as for the respective data elaboration and wireless communication modules, is provided in this work. EH devices based on the usage of kinetic energy, thermal gradients, solar radiation, airflow, and other viable energy sources, proposed so far in the literature, are thus described with a critical review of the respective specific power levels, of their potential placement on airplanes, as well as the consequently ...
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