Traditional robotics has always involved robots characterized by Von Neumann architecture, which has the following limitations: slowdowns caused by the presence of a single bus for transferring data and information, resulting in latency in the robots' reaction times, excessive energy consumption, and poor parallelism efficiency. State-of-the-art research has focused on overcoming this architecture by creating bio-inspired robots that can adapt autonomously to changes in the external environment. A further step forward towards bio-inspired robots is linked to the creation of control structures (to be integrated within the soft robots themselves) inspired by the functioning of neurons: namely, Central Pattern Generators (CPGs). The main feature of CPGs is that they have an output that differs from the input: by providing a linear input, they allow rhythmic patterns like motor activities to be obtained. They are important because they allow natural rhythmic movements to be produced, are adaptable, and allow coordination between limbs. At the state of the art, CPGs are essentially truncated conical membranes made of soft material (hollow inside), pneumatically actuated, and based on their mechanical instability. Currently, CPGs are manufactured using silicone molding technology: silicone is injected into a mold to create CPGs. This thesis is based on overcoming the problems of silicone molding by using additive manufacturing (or 3D printing) technology called Multi-Material Extrusion (M-MEX). In the following thesis, 3D-printed CPGs were created, overcoming the various limitations of silicone molding. At the same time, CPGs with new features compared to the state of the art were created and tested (in collaboration with KU Leuven University). M-MEX technology allows two materials to be extruded simultaneously in the same printing cycle: i) a thermoplastic polyurethane (TPU) and ii) a thermoplastic polyurethane filled with electrically conductive particles (cTPU) were extruded to create a fully integrated piezoresistive sensor (350% elongation) within the membrane. The use of an integrated sensor is extremely useful for creating closed-loop control strategies and receiving continuous feedback on the status of the membrane (snap – no snap). In addition, M-MEX technology has been used to combine pneumatic actuation with a new actuation technology, named electromagnetic actuation. Electromagnetic actuation has been used to create inhibition, thus unlocking a new type of CPG, CPGs equipped with mutual inhibition. Electromagnetic implementation has been integrated thanks to an intrinsic feature of M-MEX technology, such as the possibility of performing the start and stop method, which consists of stopping printing, integrating external elements (a permanent neodymium magnet), and resuming printing, completely integrating the magnet as the thermoplastic material is extruded directly onto the magnet, making it an integral part of the structure. In conclusion, the additive manufacturing technology called Multi-Material Extrusion was used to create CPGs with integrated sensors and actuation systems, without resorting to any type of assembly, providing new functionalities to CPGs that would be impossible to obtain with traditional manufacturing technologies (silicone molding) used in the state of the art. The following thesis represents a step forward towards the integration of soft, sensorized CPGs capable of mutual inhibition within soft robots to advance the physical intelligence distributed within the body of the soft robot, opening up new scenarios in bio-inspired robotics.
La robotica tradizionale ha da sempre previsto robots caratterizzati da un’architettura di Von Neumann.Allo stato dell’arte nuove ricerche si sono focalizzate sul superare questa architettura andando a realizzare robot bio-ispirati che possano adattarsi autonomamente a cambi dell’ambiente esterno.Un ulteriore passo in avanti verso robot bio-inspirati è legato alla realizzazione di strutture di controllo (da integrare all’interno dei soft robot stessi) ispirate ai neuroni nel loro funzionamento: ovvero i Central Pattern Generators(CPGs). Allo stato dell’arte la realizzazione di CPG avviene attraverso l’utilizzo della tecnologia manifatturiera del silicone molding: ovvero il silicone viene iniettato all’interno di un mold per creare CPG.Il presente lavoro di tesi si basa sul superare le problematiche del silicone molding utilizzando la tecnologia di Additive Manufacturing (o 3D printing) chiamata Multi-Material Extrusion (M-MEX). Nella seguente tesi dal titolo “3D printing of central pattern generators with embedded Electromagnetic and pneumatic actuation”, sono stati realizzati CPG stampati in 3D superando le varie limitazioni del silicone-moulding e, allo stesso tempo, sono stati creati e testati CPG con nuove funzionalità .In particolare, la tecnologia M-MEX consente di estrudere contemporaneamente 2 materiali nello stesso ciclo di stampa: in questo modo sono stati estrusi i) un termoplastico poliuretano (TPU) per creare la membrana del CPG, e ii) un termoplastico poliuretano caricato con particelle elettricamente conduttive (cTPU) per creare un sensore piezoresistivo completamente integrato all’interno della membrana. In questo modo CPGs con sensori embedded di spostamento (meccanismo piezoresistivo) sono stati realizzati, senza ricorrere a nessun assemblaggio. Inoltre, la tecnologia M-MEX è stata sfruttata per accoppiare, all’attuazione pneumatica, una nuova tecnologia di attuazione, ovvero l’attuazione elettromagnetica.In conclusione, la tecnologia di Additive Manufacturing chiamata Multi-Material Extrusion è stata usata per creare CPGs con sensoristica e sistema di attuazione integrato, senza ricorrere a nessun tipo di assemblaggio, fornendo nuove funzionalità ai CPG impossibili da ottenere con le tecnologie di fabbricazione tradizionali (silicone moulding) usate allo stato dell’arte. La seguente tesi rappresenta un passo in avanti verso l’integrazione di CPG soft, sensorizzati e capaci di mutua inibizione all’interno di soft robot per avanzare la physical intelligence distribuita all’interno del corpo del soft robot, aprendo nuovi scenari nella robotica bio-ispirata.
3D PRINTING OF CENTRAL PATTERN GENERATORS WITH EMBEDDED ELECTROMAGNETIC AND PNEUMATIC ACTUATION
LADISA, ANDREA ANTONIA
2024/2025
Abstract
Traditional robotics has always involved robots characterized by Von Neumann architecture, which has the following limitations: slowdowns caused by the presence of a single bus for transferring data and information, resulting in latency in the robots' reaction times, excessive energy consumption, and poor parallelism efficiency. State-of-the-art research has focused on overcoming this architecture by creating bio-inspired robots that can adapt autonomously to changes in the external environment. A further step forward towards bio-inspired robots is linked to the creation of control structures (to be integrated within the soft robots themselves) inspired by the functioning of neurons: namely, Central Pattern Generators (CPGs). The main feature of CPGs is that they have an output that differs from the input: by providing a linear input, they allow rhythmic patterns like motor activities to be obtained. They are important because they allow natural rhythmic movements to be produced, are adaptable, and allow coordination between limbs. At the state of the art, CPGs are essentially truncated conical membranes made of soft material (hollow inside), pneumatically actuated, and based on their mechanical instability. Currently, CPGs are manufactured using silicone molding technology: silicone is injected into a mold to create CPGs. This thesis is based on overcoming the problems of silicone molding by using additive manufacturing (or 3D printing) technology called Multi-Material Extrusion (M-MEX). In the following thesis, 3D-printed CPGs were created, overcoming the various limitations of silicone molding. At the same time, CPGs with new features compared to the state of the art were created and tested (in collaboration with KU Leuven University). M-MEX technology allows two materials to be extruded simultaneously in the same printing cycle: i) a thermoplastic polyurethane (TPU) and ii) a thermoplastic polyurethane filled with electrically conductive particles (cTPU) were extruded to create a fully integrated piezoresistive sensor (350% elongation) within the membrane. The use of an integrated sensor is extremely useful for creating closed-loop control strategies and receiving continuous feedback on the status of the membrane (snap – no snap). In addition, M-MEX technology has been used to combine pneumatic actuation with a new actuation technology, named electromagnetic actuation. Electromagnetic actuation has been used to create inhibition, thus unlocking a new type of CPG, CPGs equipped with mutual inhibition. Electromagnetic implementation has been integrated thanks to an intrinsic feature of M-MEX technology, such as the possibility of performing the start and stop method, which consists of stopping printing, integrating external elements (a permanent neodymium magnet), and resuming printing, completely integrating the magnet as the thermoplastic material is extruded directly onto the magnet, making it an integral part of the structure. In conclusion, the additive manufacturing technology called Multi-Material Extrusion was used to create CPGs with integrated sensors and actuation systems, without resorting to any type of assembly, providing new functionalities to CPGs that would be impossible to obtain with traditional manufacturing technologies (silicone molding) used in the state of the art. The following thesis represents a step forward towards the integration of soft, sensorized CPGs capable of mutual inhibition within soft robots to advance the physical intelligence distributed within the body of the soft robot, opening up new scenarios in bio-inspired robotics.| File | Dimensione | Formato | |
|---|---|---|---|
|
tesi finale.pdf
non disponibili
Dimensione
7.1 MB
Formato
Adobe PDF
|
7.1 MB | Adobe PDF |
I documenti in UNITESI sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
https://hdl.handle.net/20.500.14253/67253