Analysis of muscle coordination for the design of improved interacting robotic systems

Despite the increasing effort put in the development of robotic systems for neurorehabiltation, justified by the big potential of such applications as additional end efficient tools for therapy, their clinical effectiveness is still being discussed. Many of the systems developed to date were designed from an engineering point of view and do not meet therapy demands, which is reflected by unsatisfactory clinical outcomes. In order to improve these systems, new rehabilitation protocols need to be based upon a deeper knowledge of how motor control and muscle coordination are achieved on a neurological level, and of how they are affected by neurologic injury. In this research project, which is a combined effort between the Mechatronics group of the University of Padua and the Upper Extremity Motor Function Laboratory of the Medical University of South Carolina, we approached the study of muscle coordination by searching for fundamental coordination patters used to execute various movements and shared by different subjects. We recorded the EMG activity of 16 upper limb muscles of 15 healthy control subjects and 14 stroke patients during the execution of a wide variety of fast reaching movements. We then applied a non-negative factorization algorithm to the processed EMG envelopes and extracted motor modules, which represent the coordination strategies used by each subject. We found that a very limited set of motor modules can explain the muscle activation patterns of all healthy control subjects, and that these coordination strategies are mostly shared between dominant and non-dominant side. Furthermore, most healthy participants seem to use similar coordination patterns, and we could associate each of the most commonly shared motor modules with a corresponding biomechanical function. We also found that the effects of stroke can be seen both by looking at the number of modules and by analyzing their composition. In fact, stroke patients use significantly less modules both on their impaired and on their unimpaired side, and some of these modules can be explained as a combination of several merged modules found in healthy controls. These results suggest that motor impairment after stroke can be explained by a reduction in the set of motor modules. Together with the apparent inability to control certain modules independently, and which are therefore identified as merged, this could justify the limited movement complexity observed in stroke patients. We propose that new robotic rehabilitation protocols could use the information obtained by the extraction of motor modules to assess the patient's motor impairment and to address his/her specific needs. In fact, the comparison of the patient's modules with those identified in healthy control subjects can give precious information on the nature of the patient's disabilities, and provide guidelines for the choice of motor functions that should be trained during therapyNonostante l'impegno sempre maggiore per lo sviluppo di sistemi robotici per la neuroriabilitazione, giustificato dal grande potenziale di queste applicazioni come strumenti aggiuntivi ed efficienti per la terapia, la loro efficacia dal punto di vista clinico è tuttora discussa. Molti dei sistemi sviluppati fino ad oggi sono stati progettati da una prospettiva ingegneristica senza tener conto di alcune fondamentali richieste necessarie per la terapia, il che si riflette nei risultati clinici poco soddisfacenti ottenuti da queste soluzioni. Per migliorare questi sistemi, i nuovi protocolli per la riabilitazione devono basarsi su una conoscenza più approfondita su come il controllo motorio e la coordinazione muscolare sono ottenuti al livello neurologico, e su come sono modificati da danni al sistema nervoso. In questo progetto di ricerca, che nasce da una collaborazione tra il gruppo Mechatronics dell'Università degli Studi di Padova e il Upper Extremity Motor Function Laboratory della Medical University of South Carolina, abbiamo impostato lo studio della coordinazione partendo dalla ricerca di schemi basilari di coordinazione muscolare, usati per eseguire movimenti diversificati e condivisi da vari soggetti. Abbiamo registrato l'attività di 16 muscoli dell'arto superiore di 15 soggetti sani e di 14 pazienti con ictus durante l'esecuzione di un elevato numero di movimenti rapidi. Successivamente abbiamo applicato un algoritmo di fattorizzazione non negativa agli inviluppi dei segnali elettromiografici e abbiamo estratto i relativi moduli motori, i quali rappresentano le strategie di coordinazione usate da ogni soggetto. Abbiamo scoperto che un numero molto limitato di moduli motori può spiegare l'attività muscolare di tutti i soggetti sani, e che molte di queste strategie di coordinazione sono condivise tra il lato dominante e quello non dominante. Inoltre ci risulta che la maggior parte dei soggetti sani usi delle strategie simili, e abbiamo potuto associare ognuno dei moduli motori più comunemente condivisi con delle corrispondenti funzioni biomeccaniche. Oltre a ciò abbiamo visto che gli effetti dell'ictus possono essere quantificati osservando il numero di moduli motori e analizzando la loro composizione. Infatti i pazienti con ictus hanno un numero di moduli significativamente più basso su entrambi i lati, e alcuni di questi moduli possono essere visti come la fusione di due o più moduli riscontrati nei soggetti sani. Questi risultati indicano che le disabilità motorie post ictus possono essere spiegate da una riduzione del set di moduli motori. Insieme all'apparente inabilità nel controllare certi moduli in maniera indipendente, i quali quindi risultano come fusi, questo potrebbe giustificare la limitata complessità osservata nei pazienti con ictus. Nuovi protocolli per la riabilitazione robot-assistita potrebbero usare le informazioni ottenute dall'estrazione di moduli motori per valutare le disabilità motorie del paziente e per indirizzare la terapia verso le sue specifiche necessità. Il confronto tra i moduli motori del paziente con quelli identificati nei soggetti sani può dare delle informazioni preziose sulla natura delle disabilità del paziente, e fornire delle linee guida per la scelta delle funzioni motorie su cui indirizzare la terapi

Mixed-model sequencing optimization for an automated single station Fully Flexible Assembly System (F-FAS)

Flexible automated assembly is an emerging need in several industries. In the case of a very wide set of models and a total medium/low derived production volume, the proper assembly system to use is a single cell with high flexibility capabilities. An innovative concept in flexible automated assembly has recently been introduced: the fully flexible assembly system (F-FAS). The F-FAS relies on a single-station robotized assembly system, where a unique fully flexible feeder is responsible for the delivery of the parts needed for assembly, guaranteeing a higher level of flexibility than the traditional automated FAS. The mixed-model sequencing (MMS) problem is typically related to the assembly line system. The aim of this paper is to introduce a new class of MMS problem: the single-station mixed-model sequencing problem that arises when the parts to assemble are randomly presented on the working plane, as in the F-FAS. The authors first define theMMS in such a single-station assembly system and then propose different sequencing algorithms in order to solve it. The authors first define the problem and then propose different sequencing algorithms. With the aim of finding the best sequencing approach to use in such an assembly system, the algorithms are compared through ad hoc developed benchmarking tests, using a dedicated software application that simulates the real behavior of the work cell

Methodological considerations for behavioral studies relying on response time outcomes through online crowdsourcing platforms

Abstract This perspective paper explores challenges associated with online crowdsourced data collection, particularly focusing on longitudinal tasks with time-sensitive outcomes like response latencies. Based on our research, we identify two significant sources of bias: technical shortcomings such as low, variable frame rates, and human factors, contributing to high attrition rates. We explored potential solutions to these problems, such as enforcing hardware acceleration and defining study-specific frame rate thresholds, as well as pre-screening participants and monitoring hardware performance and task engagement over each experimental session. With this discussion, we intend to provide recommendations on how to improve the quality and reliability of data collected via online crowdsourced platforms and emphasize the need for researchers to be cognizant of potential pitfalls in online research

Modelling and Optimization of Fully Flexible Assembly Systems (F-FAS)

Purpose - The paper aims to address the modelling and optimization of fully flexible assembly systems (F-FAS), a new concept in flexible automation recently introduced by the authors. Design/methodology/approach - The paper presents a mathematical model of the F-FAS, which makes it possible to predict its efficiency, throughput and unit direct production costs, correlating such values with system and production variables. The mathematical model proposed in the paper was derived from experimental and simulation data, which were analysed for a wide range of different productions and system settings. Findings - Correlation analysis revealed that there are three main determinants of the efficiency of the F-FAS: the number of components (types of parts) used to assemble the models (production variable); the average complexity of the models to be assembled (production variable); the ratio of the average perimeter of components (production variable) over a significant dimension of the working plane (system variable). Such parameters makes it possible to estimate the maximum attainable efficiency of the F-FAS, and to calculate the optimal setting of the feeder which makes it possible to obtain such efficiency during the execution of the whole production order. Originality/value - The model presented in the paper makes it possible to quantify in advance the real potential of the F-FAS, according to the characteristics of the production mix and type of components to be assembled. By using the methodologies presented in the paper, one can first evaluate the convenience of the F-FAS approach with respect to traditional FAS technology and manual assembly, then identify the optimal design and settings of the F-FAS, according to the needs of a specific application. As a result, not only can the investment on the automated assembly system be accurately evaluated in advance, but also the return on investment can be maximized

Implementation framework for a fully flexible assembly system (F-FAS)

Purpose - This paper aims to provide a framework for the choice, design, set-up and management of a fully flexible assembly system (F-FAS). Many industrial applications for small batch productions require highly flexible automated manufacturing systems. Moreover, some extensions of the F-FAS concept are provided. Design/methodology/approach - The paper reviews recent findings regarding the F-FAS with a top-down approach, and defines an integrated implementation framework. This framework is structured into three strictly correlated phases, and the presented procedure is organized to be readily used for new industrial applications. Practical applications are presented to show how the system can satisfy flexibility demands in a variety of cases. Findings - The proposed framework is organized in three steps: convenience analysis of the F-FAS compared to a traditional flexible assembly system; an optimal design of the feeder; a choice of the set-up and sequencing algorithm yielding the highest throughput. Following these steps, the F-FAS can become an effective solution for small batch productions with frequent reconfigurations. However, due to the limited throughput, the system is not well suited for large batches. Originality/value - The presented framework allows to implement an F-FAS for a given industrial application, and to evaluate its efficacy with respect to other assembly technologies. Moreover, with the same implementation framework, the F-FAS concept can be applied to production fields that are different from assembly, as shown by the provided examples. This represents an important element of originality and of interest for its strong practical implications in different production environments. \ua9 Emerald Group Publishing Limited

Changes in muscle coordination patterns induced by exposure to a viscous force field

none4siBackground: Robotic neurorehabilitation aims at promoting the recovery of lost function after neurological injury by leveraging strategies of motor learning. One important aspect of the rehabilitation process is the improvement of muscle coordination patterns, which can be drastically altered after stroke. However, it is not fully understood if and how robotic therapy can address these deficits. The aim of our study was to find how muscle coordination, analyzed from the perspective of motor modules, could change during motor adaptation to a dynamic environment generated by a haptic interface. Methods: In our experiment we employed the traditional paradigm of exposure to a viscous force field to subjects that grasped the handle of an actuated joystick during a reaching movement (participants moved directly forward and back by 30 c m). EMG signals of ten muscles of the tested arm were recorded. We extracted motor modules from the pooled EMG data of all subjects and analyzed the muscle coordination patterns. Results: We found that the participants reacted by using a coordination strategy that could be explained by a change in the activation of motor modules used during free motion and by two complementary modules. These complementary modules aggregated changes in muscle coordination, and evolved throughout the experiment eventually maintaining a comparable structure until the late phase of re-adaptation. Conclusions: This result suggests that motor adaptation induced by the interaction with a robotic device can lead to changes in the muscle coordination patterns of the subject.noneOscari, Fabio; Finetto, Christian; Kautz, Steve A.; Rosati, GiulioOscari, Fabio; Finetto, Christian; Kautz, Steve A.; Rosati, Giuli

Sistemi di assemblaggio industriale ad elevata flessibilit\ue0

L\u2019assemblaggio flessibile \ue8 una necessit\ue0 in forte crescita per molte realt\ue0 industriali, per motivi legati principalmente all\u2019aumento della richiesta di piccoli lotti produttivi. Questo articolo vuole presentare una nuova categoria di sistemi per l\u2019assemblaggio flessibile, che chiamiamo fully-flexible assembly systems (F-FAS), la quale permette di lavorare su mix produttivi molto vari e in cui la dimensione del singolo lotto pu\uf2 essere anche di un solo prodotto. Viene poi fornito un confronto tra un sistema FAS Tradizionale e un F-FAS in termini di produttivit\ue0 e di costo orario e vengono mostrati dei primi risultati sperimentali che mettono in evidenza il comportamento reale del sistema