Diagnosis and Repair for Synthesis from Signal Temporal Logic Specifications

We address the problem of diagnosing and repairing specifications for hybrid systems formalized in signal temporal logic (STL). Our focus is on the setting of automatic synthesis of controllers in a model predictive control (MPC) framework. We build on recent approaches that reduce the controller synthesis problem to solving one or more mixed integer linear programs (MILPs), where infeasibility of a MILP usually indicates unrealizability of the controller synthesis problem. Given an infeasible STL synthesis problem, we present algorithms that provide feedback on the reasons for unrealizability, and suggestions for making it realizable. Our algorithms are sound and complete, i.e., they provide a correct diagnosis, and always terminate with a non-trivial specification that is feasible using the chosen synthesis method, when such a solution exists. We demonstrate the effectiveness of our approach on the synthesis of controllers for various cyber-physical systems, including an autonomous driving application and an aircraft electric power system

LEARNING AND VISUALIZING MUSIC SPECIFICATIONS USING PATTERN GRAPHS

ABSTRACT We describe a system to learn and visualize specifications from song(s) in symbolic and audio formats. The core of our approach is based on a software engineering procedure called specification mining. Our procedure extracts patterns from feature vectors and uses them to build pattern graphs. The feature vectors are created by segmenting song(s) and extracting time and and frequency domain features from them, such as chromagrams, chord degree and interval classification. The pattern graphs built on these feature vectors provide the likelihood of a pattern between nodes, as well as start and ending nodes. The pattern graphs learned from a song(s) describe formal specifications that can be used for human interpretable quantitatively and qualitatively song comparison or to perform supervisory control in machine improvisation. We offer results in song summarization, song and style validation and machine improvisation with formal specifications

Trajectoires pour la vérification et la commande de systémes continus et hybrides

Nous présentons un ensemble de méthodes pour la vérification et la commande de systèmes continus et hybrides, basées sur l'utilisation de trajectoires individuelles. Dans une première partie, nous précisons la classe des systèmes considérés et leurs propriétés. Nous partons de systèmes continus régis par des équations différentielles ordinaires auxquels nous ajoutons des entrées et des événements discrets, constituant ainsi une classe de systèmes dynamiques hybrides. La seconde partie est consacrée la vérification de ces systèmes basée sur le calcul d'atteignabilité. Nous étudions comment un nombre fini dé trajectoires peut couvrir l'ensemble infmi des états atteignables du système. Nous montrons qu'en utilisant une analyse de la sensibilité aux conditions initiales, une sur-approximation de l'ensemble atteignable peut être obtenue. Nous en déduisons un algorithme qui, par une sélection hiérarchique des trajectoires, trouve rapidement un comportement mauvais ou prouve qu'il n'en existe aucun. La troisième partie concerne la commande optimale et se base sur des techniques de programmation dynamique approchée. Un coût est défini pour chaque trajectoire, et la commande minimisant ce coût se déduit d'une fonction valeur définie sur l'espace d'état et que nous représentons en utilisant un approximateur de fonction. Nous utilisons l'exprience fournie par des trajectoires tests pour améliorer cette approximation. Enfin, nous utilisons les résultats de la deuxième partie pour sélectionner ces trajectoires en cohérence avec les propriétés de généralisation locales de l'approximateur de fonction et en restreignant l'exploration de l'espace d'état pour limiter les calculs.We present a set of methods for the verification and control of continuous and hybrid systems, based on the use of individual trajectories. ln the first part, we specify the class of the systems considered and their properties. We start from continuous systems governed by ordinary differential equations to which we add inputs and discrete events, thus constituting a class of hybrid dynamical systems. The second part is devoted to the verification problem and is based on reachable sets computations. We study how a finite number of trajectories can cover the infinite set of the states reachable by the system. We show that by using a sensitivity analysis w.r.t. initial conditions, an over-approxirnation of the reachable set can be obtained. We deducefrom it an algorithm which, by an iterative and hierarchical selection of the trajectories, finds quickly a bad behavior or proves that none exists. Thethird part is concerned with optimal control and is based on approximate dynamic prograrnming techniques. A cost is defined for each trajectory, and the inputs minimizing this cost are deduced from a value function defmed on the state-space and which we represent by using a function approxirnator.We use the experience provided by test trajectories to improve this approximation. Lastly, we use the results of the second part to select these trajectories in coherence with the local generalization properties of the function approximator and in order to restrict the exploration of the state-space to limit the computational cost.GRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF

Wordgen : a Timed word Generation Tool

International audienceSampling timed words out of a timed language described as a timed automaton may seem a simple task: start from the initial state, choose a transition and a delay and repeat until an accepting state is reached. Unfortunately, simple approach based on local, on-the-fly rules produces timed words from distributions that are biased in some unpredictable ways. For this reason, approaches have been developed to guarantee that the sampling follows a more desirable distribution defined over the timed language and not over the automaton. One such distribution is the maximal entropy distribution, whose implementation requires several non-trivial computational steps. In this paper, we present Wordgen which combines those different necessary steps into a lightweight standalone tool. The resulting timed words can be mapped to signals used for model-based testing and falsification of cyber-physical systems thanks to a simple interface with the Breach tool

Mining Requirements From Closed-Loop Control Models

Formal verification of a control system can be performed by checking if a model of its dynamical behavior conforms to temporal requirements. Unfortunately, adoption of formal verification in an industrial setting is a formidable challenge as design requirements are often vague, nonmodular, evolving, or sometimes simply unknown. We propose a framework to mine requirements from a closed-loop model of an industrial-scale control system, such as one specified in Simulink. The input to our algorithm is a requirement template expressed in parametric signal temporal logic: a logical formula in which concrete signal or time values are replaced with parameters. Given a set of simulation traces of the model, our method infers values for the template parameters to obtain the strongest candidate requirement satisfied by the traces. It then tries to falsify the candidate requirement using a falsification tool. If a counterexample is found, it is added to the existing set of traces and these steps are repeated; otherwise, it terminates with the synthesized requirement. Requirement mining has several usage scenarios: mined requirements can be used to formally validate future modifications of the model, they can be used to gain better understanding of legacy models or code, and can also help enhancing the process of bug finding through simulations. We demonstrate the scalability and utility of our technique on three complex case studies in the domain of automotive powertrain systems: a simple automatic transmission controller, an air-fuel controller with a mean-value model of the engine dynamics, and an industrial-size prototype airpath controller for a diesel engine. We include results on a bug found in the prototype controller by our method

Parameter Synthesis in Nonlinear Dynamical Systems: Application to Systems Biology

The dynamics of biological processes are often modeled as systems of nonlinear ordinary differential equations (ODE). An important feature of nonlinear ODEs is that seemingly minor changes in initial conditions or parameters can lead to radically different behaviors. This is problematic because in general it is never possible to know/measure the precise state of any biological system due to measurement errors. The parameter synthesis problem is to identify sets of parameters (including initial conditions) for which a given system of nonlinear ODEs does not reach a given set of undesirable states. We present an efficient algorithm for solving this problem that combines sensitivity analysis with an efficient search over initial conditions. It scales to high-dimensional models and is exact if the given model is affine. We demonstrate our method on a model of the acute inflammatory response to bacterial infection, and identify initial conditions consistent with 3 biologically relevant outcomes

Stress Urinary Incontinence in Women With Multiple Sclerosis

Purpose To report the prevalence and risk factors of stress urinary incontinence (SUI) and the prevalence of intrinsic sphincter deficiency in women with multiple sclerosis (MS). Methods We conducted a retrospective study. Female patients with MS, followed for lower urinary tract symptoms (LUTS) during a 15-year period were included. Demographic data, MS history, expanded disability status scale (EDSS) score at the urodynamic visit, obstetrical past, birth weight, LUTS, and urodynamic findings were collected. SUI was defined as incontinence during cough, or any effort. A maximum urethral closure pressure less than 30 cm H2O defined intrinsic sphincter deficiency. Results We included 363 women with a mean age of 46.7±10.8 years and a mean disease duration of 12.9±8.7 years. The incidence of relapsing remitting MS, a secondary progressive form, and a primary progressive form was 60.6%, 32.8%, and 6.6%, respectively. The prevalence of SUI was 31.4%. The prevalence of intrinsic sphincter deficiency was 1.4% and 0.8% of these patients had a SUI (P=0.300). In a multivariate analysis, women with a SUI had significantly higher birth weight (P=0.030), a pelvic organ prolapse (P=0.021), urgent urinary incontinence (P=0.006), a lower EDSS score (P=0.019), and a weaker containing effort (P<0.001). Conclusions The prevalence of SUI in women with MS was 31.4%. This symptom could affect the quality of life of women with MS

Clinical balance tests, proprioceptive system and adolescent idiopathic scoliosis

International audienceAdolescent idiopathic scoliosis (AIS) is a three-dimensional deformity of the spinal column of unknown etiology. Multiple factors could be involved, including neurosensory pathways and, potentially, an elective disorder of dynamic proprioception. The purpose of this study was to determine whether routine balance tests could be used to demonstrate an elective alteration of dynamic proprioception in AIS.This was a multicentre case-control study based on prospectively collected clinical data, in three hospitals pediatric, with spine consultation, from January 2013 through April 2015. From an original population of 547 adolescents, inclusion and non-inclusion criteria indentified 114 adolescents with right thoracic AIS (mean age 14.5 ± 1.9 years, Cobb angle 35.7 ± 15.3°) and 81 matched adolescents without scoliosis (mean age 14.1 ± 1.9 years). Participants performed three routine clinical balance tests to assess the static and dynamic proprioception: the Fukuda-Utenberger stepping test (angle of rotation in degrees and distance of displacement in cm) to assess dynamic balance; the sharpened Romberg test and the unipedal stance test (eyes closed) to assess static balance.There was no significant difference between AIS subjects and controls for the static tests, but there was a significant difference for the dynamic test for both measures: distance of displacement (p < 0.01) and angle of rotation (p < 0.0001). This result confirms our initial these: the dynamic proprioception is altered electively in AIS.These findings confirm recent AIS studies. Our results might be related to immature central integration of dynamic proprioceptive input leading to a poorly adapted motor response, particularly for postural control of the, in AIS. These balance tests can be performed in routine practice. Their validity as a biomarker for screening and monitoring purposes should be assessed