Progettazione e sviluppo di un algoritmo di controllo per un braccio robotico antropomorfo con sistema di attuazione agonista-antagonista

Nel presente lavoro di tesi si propone la progettazione e lo sviluppo del sistema di controllo della piattaforma robotica antropomorfa NEURArm, realizzata presso l'ARTS Lab, della Scuola Superiore Sant'Anna. NEURArm è un braccio robotico antropomorfo a due gradi di libertà, attuato a cavi in configurazione agonista-antagonista ed i cui link hanno inerzie pari a quelle dei segmenti dell'arto superiore dell'uomo standard. L'algoritmo di controllo che il presente lavoro si propone di progettare e sviluppare deve consentire: - l'utilizzo di NEURArm come manipolandum per lo studio delle problematiche di interazione uomo-robot; - l'utilizzo di NEURArm per l'esecuzione di un task di catching di un oggetto in movimento. Per entrambi questi obiettivi è necessario che: - il braccio antropomorfo sia backdrivable, ovvero che sia possibile con facilità l'inversione del moto attraverso l'applicazione di forze al suo end-effector, quindi che l'interfaccia risulti il più possibile trasparente all'utente; - l'impedenza meccanica di NEURArm sia regolabile ed adattabile alle specifiche esigenze del task che si vuole eseguire. D'altra parte NEURArm è munito di un sistema di attuazione idraulico, che è intrinsecamente non-backdrivable ed a elevata rigidezza. In virtù di queste considerazioni, il sistema di controllo che si intende sviluppare deve prevedere innanzitutto un controllo attivo per rendere NEURArm backdrivable. In secondo luogo, attraverso un controllo di interazione, il controllore che si intende realizzare deve consentire la regolazione e l'adattamento dell'impedenza meccanica di NEURArm alle specifiche esigenze del task da eseguire. Pertanto, il presente lavoro è articolato nei seguenti 6 punti: 1. analisi e descrizione della piattaforma NEURArm in accordo con il paradigma biomeccatronico; 2. analisi dei fondamenti teorici della robotica industriale, con particolare attenzione al modello di Lagrange della dinamica dei manipolatori e agli schemi di controllo dell'interazione (controllo di impedenza); 3. progettazione dell'algoritmo di controllo per NEURArm: controllore embedded con architettura gerarchica (Low level Control, Middle level Control, High Level Control); 4. progettazione, sviluppo ed implementazione dell'algoritmica per il Low Level Control; 5. analisi e modellazione della traiettoria del baricentro della mano durante il task di catching di un oggetto in movimento; 6. progettazione e simulazione dell'algoritmica per il Middle Level Control

Eye involvement in patients with myotonic dystrophy

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Synthetic and bio-artificial tactile sensing: a review

This paper reviews the state of the art of artificial tactile sensing, with a particular focus on bio-hybrid and fully-biological approaches. To this aim, the study of physiology of the human sense of touch and of the coding mechanisms of tactile information is a significant starting point, which is briefly explored in this review. Then, the progress towards the development of an artificial sense of touch are investigated. Artificial tactile sensing is analysed with respect to the possible approaches to fabricate the outer interface layer: synthetic skin versus bio-artificial skin. With particular respect to the synthetic skin approach, a brief overview is provided on various technologies and transduction principles that can be integrated beneath the skin layer. Then, the main focus moves to approaches characterized by the use of bio-artificial skin as an outer layer of the artificial sensory system. Within this design solution for the skin, bio-hybrid and fully-biological tactile sensing systems are thoroughly presented: while significant results have been reported for the development of tissue engineered skins, the development of mechanotransduction units and their integration is a recent trend that is still lagging behind, therefore requiring research efforts and investments. In the last part of the paper, application domains and perspectives of the reviewed tactile sensing technologies are discussed

A robotic model to investigate human motor control

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A novel hand exoskeleton with series elastic actuation for modulated torque transfer

Abstract Among wearable robotic devices, hand exoskeletons present an important and persistent challenge due to the compact dimensions and kinematic complexity of the human hand. To address these challenges, this paper introduces HandeXos-Beta (HX-β), a novel index finger-thumb exoskeleton for hand rehabilitation. The HX-β system features an innovative kinematic architecture that allows independent actuation of thumb flexion/extension and circumduction (opposition), thus enabling a variety of naturalistic and functional grip configurations. Furthermore, HX-β features a novel series-elastic actuators (SEA) architecture that directly measures externally transferred torque in real-time, and thus enables both position- and torque-controlled modes of operation, allowing implementation of both robot-in-charge and user-in-charge exercise paradigms. Finally, HX-β's adjustable orthosis, passive degrees of freedom, and under-actuated control scheme allow for optimal comfort, robot-user joint alignment, and flexible actuation for users of various hand sizes. In addition to the mechatronic design and resulting functional capabilities of HX-β, this work presents a series of physical performance characterizations, including the position- and torque-control system performance, frequency response, end effector force, and output impedance. By each measure, the HX-β exhibited performance comparable or superior to previously reported hand exoskeletons, including position and torque step response times on the order of 0.3 s, −3 dB cut-off frequencies ranging from approximately 2.5 to 4 Hz, and fingertip output forces on the order of 4 N. During use by a healthy subject in torque-controlled transparent mode, the HX-β orthosis joints exhibited appropriately low output impedance, ranging from 0.42 to −0.042 Nm/rad at 1 Hz, over a range of functional grasps performed at real-life speeds. This combination of lab bench characterizations and functional evaluation provides a comprehensive verification of the design and performance of the HandeXos Beta exoskeleton, and its suitability for clinical application in hand rehabilitation

A Wireless Flexible Sensorized Insole for Gait Analysis

This paper introduces the design and development of a novel pressure-sensitive foot insole for real-time monitoring of plantar pressure distribution during walking. The device consists of a flexible insole with 64 pressure-sensitive elements and an integrated electronic board for high-frequency data acquisition, pre-filtering, and wireless transmission to a remote data computing/storing unit. The pressure-sensitive technology is based on an optoelectronic technology developed at Scuola Superiore Sant'Anna. The insole is a low-cost and low-power battery-powered device. The design and development of the device is presented along with its experimental characterization and validation with healthy subjects performing a task of walking at different speeds, and benchmarked against an instrumented force platform

A flexible sensor technology for the distributed measurement of interaction pressure

We present a sensor technology for the measure of the physical human-robot interaction pressure developed in the last years at Scuola Superiore Sant'Anna. The system is composed of flexible matrices of opto-electronic sensors covered by a soft silicone cover. This sensory system is completely modular and scalable, allowing one to cover areas of any sizes and shapes, and to measure different pressure ranges. In this work we present the main application areas for this technology. A first generation of the system was used to monitor human-robot interaction in upper- (NEUROExos; Scuola Superiore Sant'Anna) and lower-limb (LOPES; University of Twente) exoskeletons for rehabilitation. A second generation, with increased resolution and wireless connection, was used to develop a pressure-sensitive foot insole and an improved human-robot interaction measurement systems. The experimental characterization of the latter system along with its validation on three healthy subjects is presented here for the first time. A perspective on future uses and development of the technology is finally drafted