Specification Patterns for Robotic Missions

Mobile and general-purpose robots increasingly support our everyday life, requiring dependable robotics control software. Creating such software mainly amounts to implementing their complex behaviors known as missions. Recognizing the need, a large number of domain-specific specification languages has been proposed. These, in addition to traditional logical languages, allow the use of formally specified missions for synthesis, verification, simulation, or guiding the implementation. For instance, the logical language LTL is commonly used by experts to specify missions, as an input for planners, which synthesize the behavior a robot should have. Unfortunately, domain-specific languages are usually tied to specific robot models, while logical languages such as LTL are difficult to use by non-experts. We present a catalog of 22 mission specification patterns for mobile robots, together with tooling for instantiating, composing, and compiling the patterns to create mission specifications. The patterns provide solutions for recurrent specification problems, each of which detailing the usage intent, known uses, relationships to other patterns, and---most importantly---a template mission specification in temporal logic. Our tooling produces specifications expressed in the LTL and CTL temporal logics to be used by planners, simulators, or model checkers. The patterns originate from 245 realistic textual mission requirements extracted from the robotics literature, and they are evaluated upon a total of 441 real-world mission requirements and 1251 mission specifications. Five of these reflect scenarios we defined with two well-known industrial partners developing human-size robots. We validated our patterns' correctness with simulators and two real robots

WebMonitor: Verification of Web User Interfaces

Application development for the modern Web involves sophisticated engineering workflows which include user interface aspects. Those involve Web elements typically created with HTML/CSS markup and JavaScript-like languages, yielding Web documents. WebMonitor leverages requirements formally specified in a logic able to capture both the layout of visual components as well as how they change over time, as a user interacts with them. Then, requirements are verified upon arbitrary web pages, allowing for automated support for a wide set of use cases in interaction testing and simulation. We position WebMonitor within a developer workflow, where in case of a negative result, a visual counterexample is returned. The monitoring framework we present follows a black-box approach, and as such is independent of the underlying technologies a Web application may be developed with, as well as the browser and operating system used. WebMonitoris available as open source software: https://github.com/ennioVisco/webmonitor Video demonstration of WebMonitor: https://youtu.be/hqVw0JU3k9

Γραμμική και μη-γραμμική ανάλυση λειτουργικών κινηματικών δεδομένων συγκριτικά σε πληθυσμό με και χωρίς χρόνια οσφυαλγία.

Στόχος της παρούσας μελέτης ήταν η σύγκριση της κινητικής μεταβλητότητας, όπως αυτή εκφράστηκε κυρίως με την χρήση μη-γραμμικών παραμέτρων, στην Οσφυϊκή Μοίρα της Σπονδυλικής Στήλης (ΟΜΣΣ), την λεκάνη και το κάτω άκρο μεταξύ ασθενών με Χρόνια Οσφυαλγία (ΧΟ) και υγιών συμμετεχόντων κατά την βάδιση. Δεκαέξι (16) ασθενείς με ΧΟ και δεκατρείς (13) υγιείς (μη αθλητές) συμμετείχαν στην έρευνα. Οι συμμετέχοντες περπάτησαν σε διάδρομο βάδισης υπό διαφορετικές συνθήκες βάδισης ενώ καταγράφονταν από οπτικοηλεκτρονικό σύστημα έξι (6) υπέρυθρων καμερών. Η ανάλυση της κινηματικής μεταβλητότητας της κίνησης της ΟΜΣΣ και της λεκάνης πραγματοποιήθηκε με γραμμικές (τυπική απόκλιση- SD) και μη γραμμικές παραμέτρους (μέγιστος Εκθέτης Lyapunov- LyE και Προσεγγιστική Εντροπία- ApEn). Οι συσχετίσεις μεταξύ των συμμετεχόντων έγινε με το t-test. Επιπλέον, χρησιμοποιήθηκε η ανάλυση ROC (Receiver Operating Characteristics) για τον υπολογισμό της δυνατότητας διαχωρισμού ομάδων από τις υπό μελέτη μεταβλητές. Τα αποτελέσματα ανέδειξαν σημαντικά υψηλότερες μέσες τιμές των υγιών συμμετεχόντων σε σχέση με τους ασθενείς σε επτά (7) παραμέτρους στην ΟΜΣΣ και την λεκάνη τόσο στην τυπική απόκλιση (SD) όσο και στον LyE και την ApEn καθώς και στις υπόλοιπες αρθρώσεις του κάτω άκρου (ισχίο, γόνατο, ποδοκνημική- άκρος πόδας). Ενδεικτικά, ο LyE στην λεκάνη κατά την φυσιολογική βάδιση εμφάνισε μία ευαισθησία της τάξης του 92.3% και ειδικότητα της τάξης του 90% στον διαχωρισμό των δύο ομάδων. Συμπερασματικά, οι υγιείς συμμετέχοντες εμφάνισαν υψηλότερες τιμές SD, LyE και ApEn καταδεικνύοντας υψηλότερα επίπεδα μεταβλητότητας και, συνεπώς, μία πιο χαοτική κινηματική συμπεριφορά σε σχέση με τους πάσχοντες από ΧΟ. Τα χαμηλότερα επίπεδα μεταβλητότητας μπορούν να τεκμηριωθούν εν μέρει από την προσπάθεια των ασθενών με ΧΟ να αποφύγουν επώδυνες ακραίες θέσεις του εύρους κίνησης. Υπό αυτό το πρίσμα οι μη γραμμικές παράμετροι φαίνεται να συσχετίζονται με τα ποιοτικά χαρακτηριστικά της κίνησης και πρέπει να ληφθούν υπ’ όψιν κατά την αποκατάσταση των ασθενών με ΧΟ.The aim of the study was to compare movement variability, as expressed mainly by non-linear indices, at the pelvis and lumbar between Low Back Pain (LBP) patients and healthy participants during gait. Sixteen (16) LBP patients and thirteen (13) healthy control subjects (non-athletes) participated in the study. Participants walked on a treadmill at different walking conditions while recorded by a 6-infrared camera optoelectronic system. Kinematic variability of pelvic and lumbar movement was analyzed using linear (standard deviation) and non-linear indices (Maximal Lyapunov Exponent- LyE and Approximate Entropy- ApEn). Between subjects values were compared with the t-test. Also, ROC analysis was applied in order to compute the discrimination ability of the calculated components. Results showed that healthy subjects were found to have significantly greater mean values than LBP patients at seven pelvic and lumbar components in LyE, ApEn and SD. Specifically the calculated LyE at the pelvis during normal gait was proven to have a sensitivity of 92.3% and a specificity of 90% in the discrimination of healthy subjects from LBP patients. Female subjects presented with higher variability than males. In conclusion, healthy participants presented with higher LyE, ApEn and SD values indicating higher variability levels and, therefore, a more chaotic kinematic behavior in comparison to LBP patients. Lower variability values may be partly explained by the attempt of LBP patients to avoid painful end of range of motion positions. In this perspective non- linear indices seem to relate to qualitive characteristics of movement that need to be taken into consideration during rehabilitation

Engineering topology aware adaptive security: preventing requirements violations at runtime

Adaptive security systems aim to protect critical assets in the face of changes in their operational environment. We have argued that incorporating an explicit representation of the environment’s topology enables reasoning on the location of assets being protected and the proximity of potentially harmful agents. This paper proposes to engineer topology aware adaptive security systems by identifying violations of security requirementsthat may be caused by topological changes, and selecting a setof security controls that prevent such violations. Our approach focuses on physical topologies; it maintains at runtime a live representation of the topology which is updated when assets or agents move, or when the structure of the physical space is altered. When the topology changes, we look ahead at a subset of the future system states. These states are reachable when the agents move within the physical space. If security requirements can be violated in future system states, a configuration of security controls is proactively applied to prevent the system from reaching those states. Thus, the system continuously adapts to topological stimuli, while maintaining requirements satisfaction. Security requirements are formally expressed using a propositional temporal logic, encoding spatial properties in Computation Tree Logic (CTL). The Ambient Calculus is used to represent the topology of the operational environment - including location of assets and agents - as well as to identify future system states that are reachable from the current one. The approach is demonstrated and evaluated using a substantive example concerned with physical access control

Edge-based Runtime Verification for the Internet of Things

Complex distributed systems such as the ones induced by Internet of Things (IoT) deployments, are expected to operate in compliance to their requirements. This can be checked by inspecting events flowing throughout the system, typically originating from end-devices and reflecting arbitrary actions, changes in state or sensing. Such events typically reflect the behavior of the overall IoT system – they may indicate executions which satisfy or violate its requirements. This article presents a service-based software architecture and technical framework supporting runtime verification for widely deployed, volatile IoT systems. At the lowest level, systems we consider are comprised of resource-constrained devices connected over wide area networks generating events. In our approach, monitors are deployed on edge components, receiving events originating from end-devices or other edge nodes. Temporal logic properties expressing desired requirements are then evaluated on each edge monitor in a runtime fashion. The system exhibits decentralization since evaluation occurs locally on edge nodes, and verdicts possibly affecting satisfaction of properties on other edge nodes are propagated accordingly. This reduces dependence on cloud infrastructures for IoT data collection and centralized processing. We illustrate how specification and runtime verification can be achieved in practice on a characteristic case study of smart parking. Finally, we demonstrate the feasibility of our design over a testbed instantiation, whereupon we evaluate performance and capacity limits of different hardware classes under monitoring workloads of varying intensity using state-of-the-art LPWAN technology

Specification Patterns for Robotic Missions

Mobile and general-purpose robots increasingly support our everyday life, requiring dependable robotics control software. Creating such software mainly amounts to implementing their complex behaviors known as missions. Recognizing this need, a large number of domain-specific specification languages has been proposed. These, in addition to traditional logical languages, allow the use of formally specified missions for synthesis, verification, simulation or guiding implementation. For instance, the logical language LTL is commonly used by experts to specify missions as an input for planners, which synthesize the behavior a robot should have. Unfortunately, domain-specific languages are usually tied to specific robot models, while logical languages such as LTL are difficult to use by non-experts. We present a catalog of 22 mission specification patterns for mobile robots, together with tooling for instantiating, composing, and compiling the patterns to create mission specifications. The patterns provide solutions for recurrent specification problems, each of which detailing the usage intent, known uses, relationships to other patterns, and-most importantly-a template mission specification in temporal logic. Our tooling produces specifications expressed in the temporal logics LTL and CTL to be used by planners, simulators or model checkers. The patterns originate from 245 realistic textual mission requirements extracted from the robotics literature, and they are evaluated upon a total of 441 real-world mission requirements and 1251 mission specifications. Five of these reflect scenarios we defined with two well-known industrial partners developing human-size robots. We validated our patterns' correctness with simulators and two different types of real robots

PsALM: specification of dependable robotic missions

Engineering dependable software for mobile robots is becoming increasingly important. A core asset to engineering mobile robots is the mission specification – a description of the mission that mobile robots shall achieve. Mission specifications are used, among others, to synthesize, verify, simulate or guide the engineering of robot software. However, development of precise mission specifications is challenging, as engineers need to translate requirements into specification structures often ex- pressed in a logical language – a laborious and error-prone task. Specification patterns, as solutions for recurrent specification problems have been recognized as a solution for this problem. Each pattern details the usage intent, known uses, relationships to other patterns, and—most importantly—a template mission specification in temporal logic. Patterns constitute reusable build- ing blocks that can be used by engineers to create complex mission specifications while reducing mistakes. To this end, we describe PsALM, a toolchain supporting the development of dependable robotic missions. PsALM supports the description of mission requirements through specification patterns and allows automatic generation of mission specifications. PsALM produces specifications expressed in LTL and CTL temporal logics to be used by planners, simulators and model checkers, supporting systematic mission design

Sabrina: Modeling and Visualization of Economy Data with Incremental Domain Knowledge

Investment planning requires knowledge of the financial landscape on a large scale, both in terms of geo-spatial and industry sector distribution. There is plenty of data available, but it is scattered across heterogeneous sources (newspapers, open data, etc.), which makes it difficult for financial analysts to understand the big picture. In this paper, we present Sabrina, a financial data analysis and visualization approach that incorporates a pipeline for the generation of firm-to-firm financial transaction networks. The pipeline is capable of fusing the ground truth on individual firms in a region with (incremental) domain knowledge on general macroscopic aspects of the economy. Sabrina unites these heterogeneous data sources within a uniform visual interface that enables the visual analysis process. In a user study with three domain experts, we illustrate the usefulness of Sabrina, which eases their analysis process

Mission Specification Patterns for Mobile Robots: Providing Support for Quantitative Properties

With many applications across domains as diverse as logistics, healthcare, and agriculture, service robots are in increasingly high demand. Nevertheless, the designers of these robots often struggle with specifying their tasks in a way that is both human-understandable and sufficiently precise to enable automated verification and planning of robotic missions. Recent research has addressed this problem for the functional aspects of robotic missions through the use of mission specification patterns. These patterns support the definition of robotic missions involving, for instance, the patrolling of a perimeter, the avoidance of unsafe locations within an area, or reacting to specific events. Our paper introduces a catalog of QUantitAtive RoboTic mission spEcificaTion patterns (QUARTET) that tackles the complementary and equally important challenge of specifying the reliability, performance, resource use, and other key quantitative properties of robotic missions. Identified using a methodology that included the analysis of 73 research papers published in 17 leading software engineering and robotics venues between 2014–2021, our 22 QUARTET patterns are defined in a tool-supported domain-specific language. As such, QUARTET enables: (i) the precise definition of quantitative robotic-mission requirements; and (ii) the translation of these requirements into probabilistic reward computation tree logic (PRCTL), and thus their formal verification and the automated planning of robotic missions. We demonstrate the applicability of QUARTET by showing that it supports the specification of over 95% of the quantitative robotic mission requirements from a systematically selected set of recent research papers, of which 75% can be automatically translated into PRCTL for the purposes of verification through model checking and mission planning