Kinematic directional index for the performance of redundant manipulators

Performance indexes are a powerful tool to evaluate the behavior of industrial manipulators throughout their workspace and improve their performance. When dealing with intrinsically redundant manipulators, the additional joint influences their performance; hence, it is fundamental to consider the influence of the redundant joint when evaluating the performance index. This work improves the formulation of the kinematic directional index (KDI) by considering redundant manipulators. The KDI represents an improvement over traditional indexes, as it takes into account the direction of motion when evaluating the performance of a manipulator. However, in its current formulation, it is not suitable for redundant manipulators. Therefore, we extend the index to redundant manipulators. This is achieved by adopting a geometric approach that allows identifying the appropriate redundancy to maximize the velocity of a serial manipulator along the direction of motion. This approach is applied to a 4-degree-of-freedom (DOF) planar redundant manipulator and a 7-DOF spatial articulated one. Experimental validation for the articulated robot is presented, demonstrating the effectiveness of the proposed method and its advantages

Sex difference and intra-operative tidal volume: Insights from the LAS VEGAS study

BACKGROUND: One key element of lung-protective ventilation is the use of a low tidal volume (VT). A sex difference in use of low tidal volume ventilation (LTVV) has been described in critically ill ICU patients.OBJECTIVES: The aim of this study was to determine whether a sex difference in use of LTVV also exists in operating room patients, and if present what factors drive this difference.DESIGN, PATIENTS AND SETTING: This is a posthoc analysis of LAS VEGAS, a 1-week worldwide observational study in adults requiring intra-operative ventilation during general anaesthesia for surgery in 146 hospitals in 29 countries.MAIN OUTCOME MEASURES: Women and men were compared with respect to use of LTVV, defined as VT of 8 ml kg-1 or less predicted bodyweight (PBW). A VT was deemed 'default' if the set VT was a round number. A mediation analysis assessed which factors may explain the sex difference in use of LTVV during intra-operative ventilation.RESULTS: This analysis includes 9864 patients, of whom 5425 (55%) were women. A default VT was often set, both in women and men; mode VT was 500 ml. Median [IQR] VT was higher in women than in men (8.6 [7.7 to 9.6] vs. 7.6 [6.8 to 8.4] ml kg-1 PBW, P < 0.001). Compared with men, women were twice as likely not to receive LTVV [68.8 vs. 36.0%; relative risk ratio 2.1 (95% CI 1.9 to 2.1), P < 0.001]. In the mediation analysis, patients' height and actual body weight (ABW) explained 81 and 18% of the sex difference in use of LTVV, respectively; it was not explained by the use of a default VT.CONCLUSION: In this worldwide cohort of patients receiving intra-operative ventilation during general anaesthesia for surgery, women received a higher VT than men during intra-operative ventilation. The risk for a female not to receive LTVV during surgery was double that of males. Height and ABW were the two mediators of the sex difference in use of LTVV.TRIAL REGISTRATION: The study was registered at Clinicaltrials.gov, NCT01601223

Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study

Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research

Framework for Collaborative Robotic Systems

Nell'ultimo decennio, i robot collaborativi, o più semplicemente cobot, stanno diventando sempre più comuni grazie alla loro abilità di condividere lo spazio di lavoro con l'operatore. In questo modo è possibile migliorare le prestazioni dei sistemi industriali, e in particolare quelli di assemblaggio, grazie alla possibilità di unire la flessibilità dei sistemi manuali con le prestazioni della robotica tradizionale. Per di più, è possibile automatizzare parzialmente tutti quei task che precedentemente era troppo difficile o costoso automatizzare. Nonostante i loro vantaggi, l'utilizzo di robot collaborativi nel contesto industriale è ancora limitato a causa dei loro svantaggi. Infatti, le loro prestazioni sono limitate se confrontate con i robot tradizionali, per motivi di sicurezza, e potrebbe non essere possibile ottimizzare le loro traiettorie se si considera la necessità di evitare l'operatore. Inoltre, una cella collaborativa è solitamente separata dall'impianto principale, limitando il suo impatto nella produzione. Queste considerazioni sono complicate ulteriormente nel caso di sistemi collaborativi multi-risorsa, ovvero sistemi con un numero di risorse maggiore di 2. Scopo di questo lavoro è risolvere questi svantaggi presentando un framework, quindi un set di algoritmi, che integrino i robot collaborativi nel contesto industriale, con maggiore attenzione ai sistemi collaborativi multi-risorsa. Questo significa non solo sviluppare un algoritmo di allocazione dei task e di comunicazione per gestire i cobot e i robot tradizionali che compongono l'impianto, ma anche sviluppare un set di algoritmi per stimare e migliorare le prestazioni di questi sistemi. Tutto ciò è ulteriormente complicato dalla necessità di considerare l'operatore umano, che richiede particolare attenzione. Nella prima parte, questa tesi si focalizza sull'analisi delle performance di sistemi collaborativi multi-risorsa, identificando le caratteristiche di prodotto e di processo che influenzano le performance di questi sistemi e fornire un modello che permetta di valutarne la produttività dato il layout. Per integrare i diversi cobot che compongono il sistema multi-risorsa, si presenta un framework con un set di algoritmi per assegnare correttamente i task. Questo framework può essere anche utilizzato per integrare il sistema collaborativo al sistema industriale principale. La seconda parte si focalizza sul lato umano della collaborazione uomo-robot, iniziando con la sicurezza dell'operatore presentando una strategia per evitare le collisioni. Da questa, si presenta uno studio sull'influenza dello spazio di lavoro condiviso sulle prestazioni del sistema. Infine, focalizzandosi sull'interazione fisica tra uomo e robot, si presentano due controllori adattativi basati su due metodi di apprendimento diversi. I controllori sono usati per modulare la rigidezza di un manipolatore planare usato per l'apprendimento motorio, che richiede anch'esso controllori adattativi. Infine, si presenta un confronto preliminare tra i due controllori.In the last decade, collaborative robots, or simply cobots, are becoming increasingly common thanks to their ability to safely share their workspace with a human operator. This ability may improve the performance of industrial systems, with a particular focus on assembly ones, thanks to the possibility to merge the flexibility of a manual system with the performance of traditional robotics. Moreover, it is possible to partially automate tasks that were previously too difficult or too expensive to automate. Despite their advantages, the adoption of collaborative robots is still limited in the industrial setting due to their drawbacks. Indeed, their performance are limited in comparison to traditional robots due to safety reasons, and it may not be possible to optimize their trajectory since it is necessary to avoid the operator. Moreover, a collaborative workcell is usually separated from the main industrial plant, thus limiting its effects on the production process. This is further complicated in the case of multi-resource collaborative systems, i.e., systems with a number of resources greater than 2. The aim of this work is to solve these drawbacks by presenting a framework, thus a set of algorithms, to integrate collaborative robots in the industrial setting with a great focus on multi-resources collaborative systems. This means not only to develop a task allocation and communication algorithm to manage the cobots and industrial robots composing the plant, but also to develop a set of algorithms to estimate and improve the performance of these systems. This is further complicated by the need of considering the human operator in the loop, which requires particular attention. In the first part, this dissertation focuses on the analysis of the performance of multi-resource collaborative systems, identifying the product and process characteristics that influence the productivity of these systems, and providing a model that allows evaluating the productivity of these systems given their layout. To integrate the different cobots composing the multi-resource system, a framework is presented, with a set of tools to correctly assign the tasks. This framework can also be adopted to integrate the collaborative system with the main industrial plant. The second part focuses on the human side of human-robot collaboration, starting with a focus on the safety of the operator by presenting a collision avoidance strategy. From this, an analysis of the influence of the shared workspace on the system performance is presented. Lastly, with a focus on physical human-robot interaction, two adaptive controllers based on two different learning approaches are presented. The controllers are used to modulate the impedance of a planar robot used for motor learning training, which has a similar request for adaptive controllers. Lastly, a preliminary comparison between the two controllers is presented

Experimental Investigation of a Cable Robot Recovery Strategy

Developing an emergency procedure for cable-driven parallel robots is not a trivial process, since it is not possible to halt the end-effector by quickly braking the actuators as in rigid-link manipulators. For this reason, the cable robot recovery strategy is an important topic of research, and the literature provides several approaches. However, the computational efficiency of the recovery algorithm is fundamental for real-time applications. Thus, this paper presents a recovery strategy adopted in an experimental setup consisting of a three degrees-of-freedom (3-DOF) suspended cable robot controlled by an industrial PC. The presentation of the used control system lists the industrial-grade components installed, further highlighting the industrial implication of the work. Lastly, the experimental validation of the recovery strategy proves the effectiveness of the work

Improving a Cable Robot Recovery Strategy by Actuator Dynamics

Cable-driven parallel robots offer several benefits in terms of workspace size and design cost with respect to rigid-link manipulators. However, implementing an emergency procedure for these manipulators is not trivial, since stopping the actuators abruptly does not imply that the end-effector rests at a stable position. This paper improves a previous recovery strategy by introducing the physics of the actuators, i.e., torque limits, inertia, and friction. Such features deeply affect the reachable acceleration during the recovery trajectory. The strategy has been applied to a simulated point-mass suspended cable robot with three translational degrees of freedom to prove its effectiveness and feasibility. The acceleration limits during the recovery phase were compared with the ones obtained with the previous method, thus confirming the necessity of contemplating the properties of the actuators. The proposed strategy can be implemented in a real-time environment, which makes it suitable for immediate application to an industrial environment

Design of the Drive Mechanism of a Rotating Feeding Device

Component batching can be a source of time waste in specific industrial applications, such as kitting. Kitting operations are usually performed by hoppers, but other devices can be used to optimize the process. In a previous work, a rotary device has been proved to be more efficient than hoppers; such a device allows the kitting and releasing of the components in a single rotatory movement, while traditional hoppers require at least two movements. In this paper, an improvement of such feeding device is proposed. The movement of the rotary device is driven by a four-bar linkage mechanism which is designed through functional synthesis. Thank to the four-bar linkage mechanism, the alternate motion of the rotary distributor is derived from the constant speed of the motor

Sales Kit Automated Production: An Integrated Procedure for Setup Reduction in Case of High Products Variety

Nowadays, the demand for personalized goods is increasing, with small batches of customized products. Companies are asked to cope with this need to be more competitive; thus, it is crucial to optimally set up the production process to cope with the demand. Among the products composed of several parts, sales kits occupy a significant role. Sales kits are sets of different components, supplied as a single unit. Automation is usually used to reduce the unit direct production costs for assembled products, and this is especially true for kitting since it has minimum added value, compared to other technologies. The wide range of components leads to frequent reconfiguration of the feeding devices between different products, increasing the setup time. The aim of this work is to provide a model that minimizes the setup times of automatic kitting systems when working with a high variety of products. To reach this goal, we propose to apply the traveling salesman problem (TSP) to the production process by integrating a multi-clustering model, thus increasing its appeal to several applications. This method is applied both to simulations and to a real case study, and proves to be able to provide a good solution in a reasonable time

Optimization of a Kitting Line: A Case Study

none5noopenComand, Nicola; Minto, Riccardo; Boschetti, Giovanni; Faccio, Maurizio; Rosati, GiulioComand, Nicola; Minto, Riccardo; Boschetti, Giovanni; Faccio, Maurizio; Rosati, Giuli