Monitoring system behaviors using formal specifications appears to be an effective technique in analyzing cyber-physical systems. However, to achieve intended results in monitoring, specification languages need to be intuitive, elegant, and expressive at the first place. In this paper, we propose a metric extension of well-known Halpern-Shoham (hs) logic, called Metric Compass Logic (mcl), for monitoring purposes. Originally proposed for high-level temporal reasoning, the logic hs is very expressive and enables users to specify many temporal patterns in an intuitive and elegant way. As our main contribution, we present an offline monitoring technique for timed patterns specified in mcl. Our solution is built upon the framework developed for timed regular expressions (TRE) matching but explores a different (logical) direction. We finally study several practical features concerning atomic formulas and discuss a combined timed pattern speciication language with TRE.
{"title":"Specifying Timed Patterns using Temporal Logic","authors":"Dogan Ulus, O. Maler","doi":"10.1145/3178126.3178129","DOIUrl":"https://doi.org/10.1145/3178126.3178129","url":null,"abstract":"Monitoring system behaviors using formal specifications appears to be an effective technique in analyzing cyber-physical systems. However, to achieve intended results in monitoring, specification languages need to be intuitive, elegant, and expressive at the first place. In this paper, we propose a metric extension of well-known Halpern-Shoham (hs) logic, called Metric Compass Logic (mcl), for monitoring purposes. Originally proposed for high-level temporal reasoning, the logic hs is very expressive and enables users to specify many temporal patterns in an intuitive and elegant way. As our main contribution, we present an offline monitoring technique for timed patterns specified in mcl. Our solution is built upon the framework developed for timed regular expressions (TRE) matching but explores a different (logical) direction. We finally study several practical features concerning atomic formulas and discuss a combined timed pattern speciication language with TRE.","PeriodicalId":131076,"journal":{"name":"Proceedings of the 21st International Conference on Hybrid Systems: Computation and Control (part of CPS Week)","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125203154","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
IONS In the previous sections, concrete systems and their abstractions were considered as general discrete-time control systems, deterministic or nondeterministic, finite or infinite, that can be related to each other through a storage function (in the case of subsystems) or an alternating simulation function (in the case of interconnected systems). In this section, we consider infinite, deterministic, control subsystems and provide a way of constructing their finite abstractions together with their corresponding storage functions. The construction of the finite abstraction is performed in a straightforward way. Simply, the finite state and input sets of the finite abstraction are constructed by gridding the state and input sets of the concrete subsystem with suitable grid sizes. Moreover, the transitions between those finite states are established as follows: given an initial cell and a discrete input, the concrete system is simulated for one iteration starting from the center of the cell and under the discrete input. The simulated point is contained in a cell of the grid. This implies existence of a transition between the center of the initial cell and the one containing the simulated point under the given discrete input. This is performed for all grid cells and all possible discrete inputs as defined formally in [9, Definition 7]. 5 CONSTRUCTION OF STORAGE FUNCTIONS The storage function from the finite abstraction to the concrete subsystem and vice versa is established under the assumption that the original discrete-time control subsystem is so-called incrementally passivable [9, Definition 5]. Such an incremental passivity property is described based on the existence of a function satisfying some conditions. Then, under some mild assumptions, it can be shown that this function is actually a storage function from the concrete subsystem to its finite abstraction and vice versa. Note that any stabilizable linear control system and some incrementally stabilizable control systems satisfy this property [9, Remark 3].
{"title":"Compositional Synthesis of Finite Abstractions for Networks of Systems: A Dissipativity Approach","authors":"Abdalla Swikir, A. Girard, Majid Zamani","doi":"10.1145/3178126.3187000","DOIUrl":"https://doi.org/10.1145/3178126.3187000","url":null,"abstract":"IONS In the previous sections, concrete systems and their abstractions were considered as general discrete-time control systems, deterministic or nondeterministic, finite or infinite, that can be related to each other through a storage function (in the case of subsystems) or an alternating simulation function (in the case of interconnected systems). In this section, we consider infinite, deterministic, control subsystems and provide a way of constructing their finite abstractions together with their corresponding storage functions. The construction of the finite abstraction is performed in a straightforward way. Simply, the finite state and input sets of the finite abstraction are constructed by gridding the state and input sets of the concrete subsystem with suitable grid sizes. Moreover, the transitions between those finite states are established as follows: given an initial cell and a discrete input, the concrete system is simulated for one iteration starting from the center of the cell and under the discrete input. The simulated point is contained in a cell of the grid. This implies existence of a transition between the center of the initial cell and the one containing the simulated point under the given discrete input. This is performed for all grid cells and all possible discrete inputs as defined formally in [9, Definition 7]. 5 CONSTRUCTION OF STORAGE FUNCTIONS The storage function from the finite abstraction to the concrete subsystem and vice versa is established under the assumption that the original discrete-time control subsystem is so-called incrementally passivable [9, Definition 5]. Such an incremental passivity property is described based on the existence of a function satisfying some conditions. Then, under some mild assumptions, it can be shown that this function is actually a storage function from the concrete subsystem to its finite abstraction and vice versa. Note that any stabilizable linear control system and some incrementally stabilizable control systems satisfy this property [9, Remark 3].","PeriodicalId":131076,"journal":{"name":"Proceedings of the 21st International Conference on Hybrid Systems: Computation and Control (part of CPS Week)","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124189513","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Session details: Data-driven Design","authors":"Ashutosh Trivedi","doi":"10.1145/3258029","DOIUrl":"https://doi.org/10.1145/3258029","url":null,"abstract":"","PeriodicalId":131076,"journal":{"name":"Proceedings of the 21st International Conference on Hybrid Systems: Computation and Control (part of CPS Week)","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128367631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Session details: Compositional Methods","authors":"Jyotirmoy V. Deshmukh","doi":"10.1145/3258028","DOIUrl":"https://doi.org/10.1145/3258028","url":null,"abstract":"","PeriodicalId":131076,"journal":{"name":"Proceedings of the 21st International Conference on Hybrid Systems: Computation and Control (part of CPS Week)","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122217827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We consider the problem of optimal clock allocation for a fairly general class of timed automata, TAS, under the safe assumption that all locations are reachable. Techniques similar to those used in compiler technology allow us to construct an interference graph: the problem of clock allocation for timed automata in TAS can be reduced to that of colouring this graph. We then describe a class of timed automata, TADS ⊊ TAS, for which optimal clock allocation can be computed in polynomial time, because the corresponding interference graphs are perfect. Finally, we discuss some of the difficulties in applying similar techniques to timed automata outside TAS.
{"title":"Clock Allocation in Timed Automata and Graph Colouring","authors":"N. Saeedloei, Feliks Kluzniak","doi":"10.1145/3178126.3178138","DOIUrl":"https://doi.org/10.1145/3178126.3178138","url":null,"abstract":"We consider the problem of optimal clock allocation for a fairly general class of timed automata, TAS, under the safe assumption that all locations are reachable. Techniques similar to those used in compiler technology allow us to construct an interference graph: the problem of clock allocation for timed automata in TAS can be reduced to that of colouring this graph. We then describe a class of timed automata, TADS ⊊ TAS, for which optimal clock allocation can be computed in polynomial time, because the corresponding interference graphs are perfect. Finally, we discuss some of the difficulties in applying similar techniques to timed automata outside TAS.","PeriodicalId":131076,"journal":{"name":"Proceedings of the 21st International Conference on Hybrid Systems: Computation and Control (part of CPS Week)","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122690117","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We propose an algorithm to over-approximate the reachable set of nonlinear systems with bounded, time-varying parameters and uncertain initial conditions. The algorithm is based on the conservative representation of the nonlinear dynamics by a differential inclusion consisting of a linear term and the Minkowsky sum of two convex sets. The linear term and one of the two sets are obtained by a conservative first-order over-approximation of the nonlinear dynamics with respect to the system state. The second set accounts for the effect of the time-varying parameters. A distinctive feature of the novel algorithm is the possibility to over-approximate the reachable set to any desired accuracy by appropriately choosing the parameters in the computation. We provide an example that illustrates the effectiveness of our approach.
{"title":"Accurate reachability analysis of uncertain nonlinear systems","authors":"M. Rungger, Majid Zamani","doi":"10.1145/3178126.3178127","DOIUrl":"https://doi.org/10.1145/3178126.3178127","url":null,"abstract":"We propose an algorithm to over-approximate the reachable set of nonlinear systems with bounded, time-varying parameters and uncertain initial conditions. The algorithm is based on the conservative representation of the nonlinear dynamics by a differential inclusion consisting of a linear term and the Minkowsky sum of two convex sets. The linear term and one of the two sets are obtained by a conservative first-order over-approximation of the nonlinear dynamics with respect to the system state. The second set accounts for the effect of the time-varying parameters. A distinctive feature of the novel algorithm is the possibility to over-approximate the reachable set to any desired accuracy by appropriately choosing the parameters in the computation. We provide an example that illustrates the effectiveness of our approach.","PeriodicalId":131076,"journal":{"name":"Proceedings of the 21st International Conference on Hybrid Systems: Computation and Control (part of CPS Week)","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126384251","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nima Roohi, R. Kaur, James Weimer, O. Sokolsky, Insup Lee
Signal Temporal Logic (STL) is a prominent specification formalism for real-time systems, and monitoring these specifications, specially when (for different reasons such as learning) behavior of systems can change over time, is quite important. There are three main challenges in this area: (1) full observation of system state is not possible due to noise or nuisance parameters, (2) the whole execution is not available during the monitoring, and (3) computational complexity of monitoring continuous time signals is very high. Although, each of these challenges has been addressed by different works, to the best of our knowledge, no one has addressed them all together. In this paper, we show how to extend any parameter invariant test procedure for single points in time to a parameter invariant test procedure for efficiently monitoring continuous time executions of a system against STL properties. We also show, how to extend probabilistic error guarantee of the input test procedure to a probabilistic error guarantee for the constructed test procedure.
{"title":"Parameter Invariant Monitoring for Signal Temporal Logic","authors":"Nima Roohi, R. Kaur, James Weimer, O. Sokolsky, Insup Lee","doi":"10.1145/3178126.3178140","DOIUrl":"https://doi.org/10.1145/3178126.3178140","url":null,"abstract":"Signal Temporal Logic (STL) is a prominent specification formalism for real-time systems, and monitoring these specifications, specially when (for different reasons such as learning) behavior of systems can change over time, is quite important. There are three main challenges in this area: (1) full observation of system state is not possible due to noise or nuisance parameters, (2) the whole execution is not available during the monitoring, and (3) computational complexity of monitoring continuous time signals is very high. Although, each of these challenges has been addressed by different works, to the best of our knowledge, no one has addressed them all together. In this paper, we show how to extend any parameter invariant test procedure for single points in time to a parameter invariant test procedure for efficiently monitoring continuous time executions of a system against STL properties. We also show, how to extend probabilistic error guarantee of the input test procedure to a probabilistic error guarantee for the constructed test procedure.","PeriodicalId":131076,"journal":{"name":"Proceedings of the 21st International Conference on Hybrid Systems: Computation and Control (part of CPS Week)","volume":"71 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122164651","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper deals with input/output-to-state stability (IOSS) of continuous-time switched nonlinear systems under restricted switching. The switching signals obey restrictions on: (i) transitions between subsystems, and (ii) dwell time on subsystems. Given a family of systems, possibly containing non-IOSS dynamics, we present an algorithm to construct a time-dependent switching signal that guarantees IOSS of the resulting switched system under these restrictions. The main apparatus for our analysis are multiple Lyapunov-like functions and graph-theoretic tools.
{"title":"Stabilizing switched nonlinear systems under restricted switching","authors":"A. Kundu","doi":"10.1145/3178126.3178130","DOIUrl":"https://doi.org/10.1145/3178126.3178130","url":null,"abstract":"This paper deals with input/output-to-state stability (IOSS) of continuous-time switched nonlinear systems under restricted switching. The switching signals obey restrictions on: (i) transitions between subsystems, and (ii) dwell time on subsystems. Given a family of systems, possibly containing non-IOSS dynamics, we present an algorithm to construct a time-dependent switching signal that guarantees IOSS of the resulting switched system under these restrictions. The main apparatus for our analysis are multiple Lyapunov-like functions and graph-theoretic tools.","PeriodicalId":131076,"journal":{"name":"Proceedings of the 21st International Conference on Hybrid Systems: Computation and Control (part of CPS Week)","volume":"1 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131574999","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, we explain the architecture and implementation of the tool Averist that performs stability verification for linear hybrid systems. This tool implements a hybridization method for approximating linear hybrid systems by hybrid systems with polyhedral inclusion dynamics. It also implements a new counterexample guided abstraction refinement framework for analyzing the hybrid systems with polyhedral inclusion dynamics that are generated as a result of the hybridization. Some of the main features of our tool are as follows: (1) our tool is based on algorithmic techniques that do not rely on the computation of Lyapunov functions, (2) it returns a counterexample when it fails to establish stability, (3) it is less prone to numerical instability issues as compared to Lyapunov function based tools.
{"title":"Averist: Algorithmic Verifier for Stability of Linear Hybrid Systems","authors":"Miriam García Soto, P. Prabhakar","doi":"10.1145/3178126.3178154","DOIUrl":"https://doi.org/10.1145/3178126.3178154","url":null,"abstract":"In this paper, we explain the architecture and implementation of the tool Averist that performs stability verification for linear hybrid systems. This tool implements a hybridization method for approximating linear hybrid systems by hybrid systems with polyhedral inclusion dynamics. It also implements a new counterexample guided abstraction refinement framework for analyzing the hybrid systems with polyhedral inclusion dynamics that are generated as a result of the hybridization. Some of the main features of our tool are as follows: (1) our tool is based on algorithmic techniques that do not rely on the computation of Lyapunov functions, (2) it returns a counterexample when it fails to establish stability, (3) it is less prone to numerical instability issues as compared to Lyapunov function based tools.","PeriodicalId":131076,"journal":{"name":"Proceedings of the 21st International Conference on Hybrid Systems: Computation and Control (part of CPS Week)","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116800953","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Gaukler, Andreas Michalka, Peter Ulbrich, Tobias Klaus
As control applications are particularly sensitive to timing variations, the Quality of Control (QoC) is degraded by varying execution conditions of the underlying real-time system. In particular, transitions between different execution or environmental conditions pose a significant issue as they may impact the QoC unexpectedly. So far, the QoC is usually evaluated either in a stationary, time-invariant way, which cannot analyze said transitions, or by simulation, which becomes inefficient when confronted with random influencing factors. In this paper, we propose a new perspective on QoC evaluation for modern, adaptive real-time systems with varying timing conditions. For this, we present a time-variant stochastic assessment approach that incorporates the effects mentioned before. Our results demonstrate that adaptive scheduling and runtime behavior considerably impacts the QoC. At the same time, the proposed scheme significantly outperforms a traditional simulation.
{"title":"A New Perspective on Quality Evaluation for Control Systems with Stochastic Timing","authors":"M. Gaukler, Andreas Michalka, Peter Ulbrich, Tobias Klaus","doi":"10.1145/3178126.3178134","DOIUrl":"https://doi.org/10.1145/3178126.3178134","url":null,"abstract":"As control applications are particularly sensitive to timing variations, the Quality of Control (QoC) is degraded by varying execution conditions of the underlying real-time system. In particular, transitions between different execution or environmental conditions pose a significant issue as they may impact the QoC unexpectedly. So far, the QoC is usually evaluated either in a stationary, time-invariant way, which cannot analyze said transitions, or by simulation, which becomes inefficient when confronted with random influencing factors. In this paper, we propose a new perspective on QoC evaluation for modern, adaptive real-time systems with varying timing conditions. For this, we present a time-variant stochastic assessment approach that incorporates the effects mentioned before. Our results demonstrate that adaptive scheduling and runtime behavior considerably impacts the QoC. At the same time, the proposed scheme significantly outperforms a traditional simulation.","PeriodicalId":131076,"journal":{"name":"Proceedings of the 21st International Conference on Hybrid Systems: Computation and Control (part of CPS Week)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122267086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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