Pub Date : 2015-10-04DOI: 10.1109/EMSOFT.2015.7318264
Mladen Skelin, Marc Geilen, Francky Catthoor, Sverre Hendseth
The FSM-based scenario-aware data ow (FSM-SADF) model of computation has been introduced to facilitate the analysis of dynamic streaming applications. FSM-SADF interprets application's execution as an execution of a sequence of static modes of operation called scenarios. Each scenario is modeled using a synchronous data ow (SDF) graph (SDFG), while a finite-state machine (FSM) is used to encode scenario occurrence patterns. However, FSM-SADF can precisely capture only those dynamic applications whose behaviors can be abstracted into a reasonably sized set of scenarios (coarse-grained dynamism). Nevertheless, in many cases, the application may exhibit thousands or even millions of behaviours (fine-grained dynamism). In this work, we generalize the concept of FSM-SADF to one that is able to model dynamic applications exhibiting fine-grained dynamism. We achieve this by applying parametrization to the FSM-SADF's base model, i.e. SDF, and defining scenarios over parametrized SDFGs. We refer to the extension as parametrized FSM-SADF (PFSM-SADF). Thereafter, we present a novel and a fully parametric analysis technique that allows us to derive tight worst-case performance (throughput and latency) guarantees for PFSM-SADF specifications. We evaluate our approach on a realistic case-study from the multimedia domain.
{"title":"Parametrized dataflow scenarios","authors":"Mladen Skelin, Marc Geilen, Francky Catthoor, Sverre Hendseth","doi":"10.1109/EMSOFT.2015.7318264","DOIUrl":"https://doi.org/10.1109/EMSOFT.2015.7318264","url":null,"abstract":"The FSM-based scenario-aware data ow (FSM-SADF) model of computation has been introduced to facilitate the analysis of dynamic streaming applications. FSM-SADF interprets application's execution as an execution of a sequence of static modes of operation called scenarios. Each scenario is modeled using a synchronous data ow (SDF) graph (SDFG), while a finite-state machine (FSM) is used to encode scenario occurrence patterns. However, FSM-SADF can precisely capture only those dynamic applications whose behaviors can be abstracted into a reasonably sized set of scenarios (coarse-grained dynamism). Nevertheless, in many cases, the application may exhibit thousands or even millions of behaviours (fine-grained dynamism). In this work, we generalize the concept of FSM-SADF to one that is able to model dynamic applications exhibiting fine-grained dynamism. We achieve this by applying parametrization to the FSM-SADF's base model, i.e. SDF, and defining scenarios over parametrized SDFGs. We refer to the extension as parametrized FSM-SADF (PFSM-SADF). Thereafter, we present a novel and a fully parametric analysis technique that allows us to derive tight worst-case performance (throughput and latency) guarantees for PFSM-SADF specifications. We evaluate our approach on a realistic case-study from the multimedia domain.","PeriodicalId":297297,"journal":{"name":"2015 International Conference on Embedded Software (EMSOFT)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130084097","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}
Pub Date : 2015-10-04DOI: 10.1109/EMSOFT.2015.7318258
Goran Frehse
In set-based reachability, a cover of the reachable states of a hybrid system is obtained by repeatedly computing one-step successor states. It can be used to show safety or to obtain quantitative information, e.g., for measuring the jitter in an oscillator circuit. In general, one-step successors can only be computed approximately and are difficult to scale in the number of continuous variables. The approximation error requires particular attention since it can accumulate rapidly, leading to a coarse cover, prohibitive state explosion, or preventing termination. In this paper, we propose an approach with precise control over the balance between approximation error and scalability. By lazy evaluation of set representations, the precision can be increased in a targeted manner, e.g., to show that a particular transition is spurious. Each evaluation step scales well in the number of continuous variables. The set representations are particularly suited for clustering and containment checking, which are essential for reducing the state explosion. This provides the building blocks for re ning the cover of the reachable set just enough to show a property of interest. The approach is illustrated on several examples.
{"title":"Reachability of hybrid systems in space-time","authors":"Goran Frehse","doi":"10.1109/EMSOFT.2015.7318258","DOIUrl":"https://doi.org/10.1109/EMSOFT.2015.7318258","url":null,"abstract":"In set-based reachability, a cover of the reachable states of a hybrid system is obtained by repeatedly computing one-step successor states. It can be used to show safety or to obtain quantitative information, e.g., for measuring the jitter in an oscillator circuit. In general, one-step successors can only be computed approximately and are difficult to scale in the number of continuous variables. The approximation error requires particular attention since it can accumulate rapidly, leading to a coarse cover, prohibitive state explosion, or preventing termination. In this paper, we propose an approach with precise control over the balance between approximation error and scalability. By lazy evaluation of set representations, the precision can be increased in a targeted manner, e.g., to show that a particular transition is spurious. Each evaluation step scales well in the number of continuous variables. The set representations are particularly suited for clustering and containment checking, which are essential for reducing the state explosion. This provides the building blocks for re ning the cover of the reachable set just enough to show a property of interest. The approach is illustrated on several examples.","PeriodicalId":297297,"journal":{"name":"2015 International Conference on Embedded Software (EMSOFT)","volume":"76 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128234728","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}
Pub Date : 2015-10-04DOI: 10.1109/EMSOFT.2015.7318259
P. Schrammel
Linear dynamical systems are ubiquitous in hybrid systems, both as physical models or as software control modules. Therefore we need an unbounded-time reachability analysis that can cope with industrial-scale hybrid system models with hundreds of variables. Abstract acceleration is a method developed for the unbounded-time polyhedral reachability analysis of linear software loops that has made promising progress in recent years. The method relies on a relaxation of the solution of the linear recurrence equation, leading to a precise convex over-approximation of the set of reachable states. It has been shown to be competitive with alternative approaches using set-based simulation or constraint solving. This paper explains the basic concepts of the technique, surveys recent advances of the technique towards the application to hybrid discrete and continuous-time linear dynamical systems, and formulates challenges to be tackled.
{"title":"Unbounded-time reachability analysis of hybrid systems by abstract acceleration","authors":"P. Schrammel","doi":"10.1109/EMSOFT.2015.7318259","DOIUrl":"https://doi.org/10.1109/EMSOFT.2015.7318259","url":null,"abstract":"Linear dynamical systems are ubiquitous in hybrid systems, both as physical models or as software control modules. Therefore we need an unbounded-time reachability analysis that can cope with industrial-scale hybrid system models with hundreds of variables. Abstract acceleration is a method developed for the unbounded-time polyhedral reachability analysis of linear software loops that has made promising progress in recent years. The method relies on a relaxation of the solution of the linear recurrence equation, leading to a precise convex over-approximation of the set of reachable states. It has been shown to be competitive with alternative approaches using set-based simulation or constraint solving. This paper explains the basic concepts of the technique, surveys recent advances of the technique towards the application to hybrid discrete and continuous-time linear dynamical systems, and formulates challenges to be tackled.","PeriodicalId":297297,"journal":{"name":"2015 International Conference on Embedded Software (EMSOFT)","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127287860","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}
Pub Date : 2015-10-04DOI: 10.1109/EMSOFT.2015.7318256
L. Thiele, Pratyush Kumar
In this paper, we take a dynamical systems perspective of real-time systems. In particular, we investigate the evolution of response times of periodic jobs and aim to show that oscillatory and chaotic behavior can be exhibited by standard scheduling algorithms. To this end, we present a simple periodic task specification that leads to oscillations of response times for a fixed priority scheduler. We then show three task specifications that lead to complex dynamic behavior under various scheduling algorithms: (a) round robin, (b) multiprocessor fixed-priority, and (c) priority inheritance protocol. As a practical validation of the results, we implemented the multiprocessor fixed-priority scheduler using POSIX threads and standard locking mechanisms. Finally, we discuss general observations and implications of the observed and proven phenomena.
{"title":"Can real-time systems be chaotic?","authors":"L. Thiele, Pratyush Kumar","doi":"10.1109/EMSOFT.2015.7318256","DOIUrl":"https://doi.org/10.1109/EMSOFT.2015.7318256","url":null,"abstract":"In this paper, we take a dynamical systems perspective of real-time systems. In particular, we investigate the evolution of response times of periodic jobs and aim to show that oscillatory and chaotic behavior can be exhibited by standard scheduling algorithms. To this end, we present a simple periodic task specification that leads to oscillations of response times for a fixed priority scheduler. We then show three task specifications that lead to complex dynamic behavior under various scheduling algorithms: (a) round robin, (b) multiprocessor fixed-priority, and (c) priority inheritance protocol. As a practical validation of the results, we implemented the multiprocessor fixed-priority scheduler using POSIX threads and standard locking mechanisms. Finally, we discuss general observations and implications of the observed and proven phenomena.","PeriodicalId":297297,"journal":{"name":"2015 International Conference on Embedded Software (EMSOFT)","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125211511","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}
Pub Date : 2015-10-04DOI: 10.1109/EMSOFT.2015.7318260
Xueguang Wu, Liqian Chen, A. Miné, Wei Dong, Ji Wang
Embedded software often involves intensive numerical computations and thus can contain a number of numerical runtime errors. The technique of numerical static analysis is of practical importance for checking the correctness of embedded software. However, most of the existing approaches of numerical static analysis consider sequential programs, while interrupts are a commonly used technique that introduces concurrency in embedded systems. To this end, a numerical static analysis approach is desired for embedded software with interrupts. In this paper, we propose a sound numerical static analysis approach specifically for interrupt-driven programs based on sequentialization techniques. A key benefit of using sequentialization is the ability to leverage the power of the state-of-the-art analysis and verification techniques for sequential programs to analyze interrupt-driven programs. To be more clear, we first propose a sequentialization algorithm to sequentialize interrupt-driven programs into non-deterministic sequential programs according to the semantics of interrupts. On this basis, we leverage the power of numerical abstract interpretation to analyze numerical properties of the sequentialized programs. Moreover, to improve the analysis precision, we design specific abstract domains to analyze sequentialized interrupt-driven programs by considering their specific features. Finally, we present encouraging experimental results obtained by our prototype implementation.
{"title":"Numerical static analysis of interrupt-driven programs via sequentialization","authors":"Xueguang Wu, Liqian Chen, A. Miné, Wei Dong, Ji Wang","doi":"10.1109/EMSOFT.2015.7318260","DOIUrl":"https://doi.org/10.1109/EMSOFT.2015.7318260","url":null,"abstract":"Embedded software often involves intensive numerical computations and thus can contain a number of numerical runtime errors. The technique of numerical static analysis is of practical importance for checking the correctness of embedded software. However, most of the existing approaches of numerical static analysis consider sequential programs, while interrupts are a commonly used technique that introduces concurrency in embedded systems. To this end, a numerical static analysis approach is desired for embedded software with interrupts. In this paper, we propose a sound numerical static analysis approach specifically for interrupt-driven programs based on sequentialization techniques. A key benefit of using sequentialization is the ability to leverage the power of the state-of-the-art analysis and verification techniques for sequential programs to analyze interrupt-driven programs. To be more clear, we first propose a sequentialization algorithm to sequentialize interrupt-driven programs into non-deterministic sequential programs according to the semantics of interrupts. On this basis, we leverage the power of numerical abstract interpretation to analyze numerical properties of the sequentialized programs. Moreover, to improve the analysis precision, we design specific abstract domains to analyze sequentialized interrupt-driven programs by considering their specific features. Finally, we present encouraging experimental results obtained by our prototype implementation.","PeriodicalId":297297,"journal":{"name":"2015 International Conference on Embedded Software (EMSOFT)","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122334687","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}
Pub Date : 2015-10-04DOI: 10.1109/EMSOFT.2015.7318254
Sanjoy Baruah
A federated approach to the multiprocessor scheduling of systems of independent recurrent tasks is considered, in which each task is either restricted to execute preemptively upon a single processor, or may execute upon multiple processors but gets exclusive access to all these processors. Efficient polynomial-time algorithms are derived here for the federated schedulability analysis and run-time scheduling of recurrent task systems that are represented by the conditional sporadic DAG tasks model. The performance of these algorithms is characterized via a speedup factor metric, which quanti es the combined cost of both restricting oneself to the federated scheduling paradigm, and of requiring the scheduling algorithms to run in polynomial time.
{"title":"The federated scheduling of systems of conditional sporadic DAG tasks","authors":"Sanjoy Baruah","doi":"10.1109/EMSOFT.2015.7318254","DOIUrl":"https://doi.org/10.1109/EMSOFT.2015.7318254","url":null,"abstract":"A federated approach to the multiprocessor scheduling of systems of independent recurrent tasks is considered, in which each task is either restricted to execute preemptively upon a single processor, or may execute upon multiple processors but gets exclusive access to all these processors. Efficient polynomial-time algorithms are derived here for the federated schedulability analysis and run-time scheduling of recurrent task systems that are represented by the conditional sporadic DAG tasks model. The performance of these algorithms is characterized via a speedup factor metric, which quanti es the combined cost of both restricting oneself to the federated scheduling paradigm, and of requiring the scheduling algorithms to run in polynomial time.","PeriodicalId":297297,"journal":{"name":"2015 International Conference on Embedded Software (EMSOFT)","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128111591","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}
Pub Date : 2015-10-04DOI: 10.1109/EMSOFT.2015.7318263
Guillaume Baudart, A. Benveniste, T. Bourke
Loosely Time-Triggered Architectures (LTTAs) are a proposal for constructing distributed embedded control systems. They build on the quasi-periodic architecture, where computing units execute `almost periodically', by adding a thin layer of middleware that facilitates the implementation of synchronous applications. In this paper, we show how the deployment of a synchronous application on a quasi-periodic architecture can be modeled using a synchronous formalism. Then we detail two protocols, Back-Pressure LTTA, reminiscent of elastic circuits, and Time-Based LTTA, based on waiting. Compared to previous work, we present controller models that can be compiled for execution and a simplified version of the Time-Based protocol. We also compare the LTTA approach with architectures based on clock synchronization.
{"title":"Loosely time-triggered architectures: improvements and comparisons","authors":"Guillaume Baudart, A. Benveniste, T. Bourke","doi":"10.1109/EMSOFT.2015.7318263","DOIUrl":"https://doi.org/10.1109/EMSOFT.2015.7318263","url":null,"abstract":"Loosely Time-Triggered Architectures (LTTAs) are a proposal for constructing distributed embedded control systems. They build on the quasi-periodic architecture, where computing units execute `almost periodically', by adding a thin layer of middleware that facilitates the implementation of synchronous applications. In this paper, we show how the deployment of a synchronous application on a quasi-periodic architecture can be modeled using a synchronous formalism. Then we detail two protocols, Back-Pressure LTTA, reminiscent of elastic circuits, and Time-Based LTTA, based on waiting. Compared to previous work, we present controller models that can be compiled for execution and a simplified version of the Time-Based protocol. We also compare the LTTA approach with architectures based on clock synchronization.","PeriodicalId":297297,"journal":{"name":"2015 International Conference on Embedded Software (EMSOFT)","volume":"462 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125815037","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}
Pub Date : 2015-10-04DOI: 10.1109/EMSOFT.2015.7318279
Ratan Lal, P. Prabhakar
We consider the problem of computing a bounded error approximation of the solution over a bounded time [0,T], of a parameterized linear system, x(t) = Ax(t), where A is constrained by a compact polyhedron Ω. Our method consists of sampling the time domain [0,T] as well as the parameter space Ω and constructing a continuous piecewise bilinear function which interpolates the solution of the parameterized system at these sample points. More precisely, given an ε > 0, we compute a sampling interval δ > 0, such that the piecewise bilinear function obtained from the sample points is within ε of the original trajectory. We present experimental results which suggest that our method is scalable.
{"title":"Bounded error flowpipe computation of parameterized linear systems","authors":"Ratan Lal, P. Prabhakar","doi":"10.1109/EMSOFT.2015.7318279","DOIUrl":"https://doi.org/10.1109/EMSOFT.2015.7318279","url":null,"abstract":"We consider the problem of computing a bounded error approximation of the solution over a bounded time [0,T], of a parameterized linear system, x(t) = Ax(t), where A is constrained by a compact polyhedron Ω. Our method consists of sampling the time domain [0,T] as well as the parameter space Ω and constructing a continuous piecewise bilinear function which interpolates the solution of the parameterized system at these sample points. More precisely, given an ε > 0, we compute a sampling interval δ > 0, such that the piecewise bilinear function obtained from the sample points is within ε of the original trajectory. We present experimental results which suggest that our method is scalable.","PeriodicalId":297297,"journal":{"name":"2015 International Conference on Embedded Software (EMSOFT)","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122180499","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}
Pub Date : 2015-10-04DOI: 10.1109/EMSOFT.2015.7318274
Farley Lai, Daniel Schmidt, O. Chipara
Memory management is a crucial aspect of mobile sensing applications that must process high-rate data streams in an energy-efficient manner. Our work is done in the context of synchronous data-flow models in which applications are implemented as a graph of components that exchange data at fixed and known rates over FIFO channels. In this paper, we show that it is feasible to leverage the restricted semantics of synchronous data-flow models to optimize memory management. Our memory optimization approach includes two components: (1) We use abstract interpretation to analyze the complete memory behavior of a mobile sensing application and identify data sharing opportunities across components according to the live ranges of exchanged samples. Experiments indicate that the static analysis is precise for a majority of considered stream applications whose control logic does not depend on input data. (2) We propose novel heuristics for memory allocation that leverage the graph structure of applications to optimize data exchanges between application components to achieve not only significantly lower memory footprints but also increased stream processing throughput. We incorporate code generation techniques that transform a stream program into efficient C code. The memory optimizations are implemented as a new compiler for the StreamIt programming language. Experiments show that our memory optimizations reduce memory footprint by as much as 96% while matching or improving the performance of the StreamIt compiler with cache optimizations enabled. These results suggest that highly efficient stream processing engines may be built using synchronous data-flow languages.
{"title":"Static memory management for efficient mobile sensing applications","authors":"Farley Lai, Daniel Schmidt, O. Chipara","doi":"10.1109/EMSOFT.2015.7318274","DOIUrl":"https://doi.org/10.1109/EMSOFT.2015.7318274","url":null,"abstract":"Memory management is a crucial aspect of mobile sensing applications that must process high-rate data streams in an energy-efficient manner. Our work is done in the context of synchronous data-flow models in which applications are implemented as a graph of components that exchange data at fixed and known rates over FIFO channels. In this paper, we show that it is feasible to leverage the restricted semantics of synchronous data-flow models to optimize memory management. Our memory optimization approach includes two components: (1) We use abstract interpretation to analyze the complete memory behavior of a mobile sensing application and identify data sharing opportunities across components according to the live ranges of exchanged samples. Experiments indicate that the static analysis is precise for a majority of considered stream applications whose control logic does not depend on input data. (2) We propose novel heuristics for memory allocation that leverage the graph structure of applications to optimize data exchanges between application components to achieve not only significantly lower memory footprints but also increased stream processing throughput. We incorporate code generation techniques that transform a stream program into efficient C code. The memory optimizations are implemented as a new compiler for the StreamIt programming language. Experiments show that our memory optimizations reduce memory footprint by as much as 96% while matching or improving the performance of the StreamIt compiler with cache optimizations enabled. These results suggest that highly efficient stream processing engines may be built using synchronous data-flow languages.","PeriodicalId":297297,"journal":{"name":"2015 International Conference on Embedded Software (EMSOFT)","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123809868","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}
Pub Date : 2015-10-04DOI: 10.1109/EMSOFT.2015.7318269
Truong X. Nghiem, R. Mangharam
Peak power consumption is a universal problem across energy control systems in electrical grids, buildings, and industrial automation where the uncoordinated operation of multiple controllers result in temporally correlated electricity demand surges (or peaks). While there exist several diferent approaches to balance power consumption by load shifting and load shedding, they operate on coarse grained time scales and do not help in de-correlating energy sinks. The Energy System Scheduling Problem is particularly hard due to its binary control variables. Its complexity grows exponentially with the scale of the system, making it impossible to handle systems with more than a few variables. We developed a scalable approach for fine-grained scheduling of energy control systems that novelly combines techniques from control theory and computer science. The original system with binary control variables are approximated by an averaged system whose inputs are the utilization values of the binary inputs within a given period. The error between the two systems can be bounded, which allows us to derive a safety constraint for the averaged system so that the original system's safety is guaranteed. To further reduce the complexity of the scheduling problem, we abstract the averaged system by a simple single-state single-input dynamical system whose control input is the upper-bound of the total demand of the system. This model abstraction is achieved by extending the concept of simulation relations between transition systems to allow for input constraints between the systems. We developed conditions to test for simulation relations as well as algorithms to compute such a model abstraction. As a consequence, we only need to solve a small linear program to compute an optimal bound of the total demand. The total demand is then broken down, by solving a linear program much smaller than the original program, to individual utilization values of the subsystems, whose actual schedule is then obtained by a low-level scheduling algorithm. Numerical simulations in Matlab show the e ectiveness and scalability of our approach.
{"title":"Scalable scheduling of energy control systems","authors":"Truong X. Nghiem, R. Mangharam","doi":"10.1109/EMSOFT.2015.7318269","DOIUrl":"https://doi.org/10.1109/EMSOFT.2015.7318269","url":null,"abstract":"Peak power consumption is a universal problem across energy control systems in electrical grids, buildings, and industrial automation where the uncoordinated operation of multiple controllers result in temporally correlated electricity demand surges (or peaks). While there exist several diferent approaches to balance power consumption by load shifting and load shedding, they operate on coarse grained time scales and do not help in de-correlating energy sinks. The Energy System Scheduling Problem is particularly hard due to its binary control variables. Its complexity grows exponentially with the scale of the system, making it impossible to handle systems with more than a few variables. We developed a scalable approach for fine-grained scheduling of energy control systems that novelly combines techniques from control theory and computer science. The original system with binary control variables are approximated by an averaged system whose inputs are the utilization values of the binary inputs within a given period. The error between the two systems can be bounded, which allows us to derive a safety constraint for the averaged system so that the original system's safety is guaranteed. To further reduce the complexity of the scheduling problem, we abstract the averaged system by a simple single-state single-input dynamical system whose control input is the upper-bound of the total demand of the system. This model abstraction is achieved by extending the concept of simulation relations between transition systems to allow for input constraints between the systems. We developed conditions to test for simulation relations as well as algorithms to compute such a model abstraction. As a consequence, we only need to solve a small linear program to compute an optimal bound of the total demand. The total demand is then broken down, by solving a linear program much smaller than the original program, to individual utilization values of the subsystems, whose actual schedule is then obtained by a low-level scheduling algorithm. Numerical simulations in Matlab show the e ectiveness and scalability of our approach.","PeriodicalId":297297,"journal":{"name":"2015 International Conference on Embedded Software (EMSOFT)","volume":"66 9","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114050731","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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