| 1. |
- Andersson, Martin, et al.
(författare)
-
Co-simulation of Mobile Wireless Networked Embedded Systems in Physical Environments
- 2005
-
Ingår i: RTiS 2005 – Proceedings of Real Time in Sweden 2005, the 8th Biennial SNART Conference on Real-Time Systems (Skövde University Studies in Informatics). - 1653-2325. - 9163173492 ; 2005:1
-
Konferensbidrag (refereegranskat)abstract
- Embedded systems are becoming increasingly networked and aredeployed in application areas that require close interaction withtheir physical environment. Examples include distributed mobileagents and wireless sensor/actuator networks. The complexity ofthese applications make co-simulation a necessary tool during systemdevelopment. This paper presents a simulation environment thatfacilitates simulation of computer nodes and communication networksinteracting with the continuous-time dynamics of the real world.Features of the simulator include interrupthandling, task scheduling, wired and wireless communication, localclocks, dynamic voltage scaling, and battery-driven operation.Two simulation case studies are presented: a simple communicationscenario and a mobile robot soccer game.
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| 2. |
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| 3. |
- Andersson, Martin, et al.
(författare)
-
Simulation of Wireless Networked Control Systems
- 2005
-
Ingår i: Proceedings of the 44th IEEE Conference on Decision and Control and the 2005 European Control Conference. - 0780395689 ; , s. 476-481
-
Konferensbidrag (refereegranskat)abstract
- Embedded systems are becoming increasingly networked and are deployed in application areas that require close interaction with their physical environment. Examples include distributed mobile agents and wireless sensor/actuator networks. The complexity of these applications make co-simulation a necessary tool during system development. This paper presents a simulation environment that facilitates simulation of computer nodes and communication networks interacting with the continuous-time dynamics of the real world. Features of the simulator include interrupt handling, task scheduling, wired and wireless communication, local clocks, dynamic voltage scaling, and battery-driven operation. Two simulation case studies are presented: a simple communication scenario and a mobile robot soccer game.
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| 4. |
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| 5. |
- Bini, Enrico, et al.
(författare)
-
Delay-Aware Period Assignment in Control Systems
- 2008
-
Konferensbidrag (refereegranskat)abstract
- We consider the problem of optimal static period assignment for multiple independent control tasks executing on the same CPU. Previous works have assumed that the control performance can be expressed as a function of the sampling rate only. Arguing that the control delay has a large impact on the control performance, in this work we include the control delay in the cost function. The delay is estimated using an approximate response-time analysis. Assuming linear cost functions for the controllers then allows us to solve the optimal period assignment problem analytically. The performance improvements over previous methods are verified in evaluations on synthetic task sets as well as detailed co-simulations of the controllers, the plants, and the scheduler.
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| 6. |
- Buttazzo, Giorgio, et al.
(författare)
-
Comparative Assessment and Evaluation of Jitter Control Methods
- 2007
-
Konferensbidrag (refereegranskat)abstract
- Most control systems involve the execution of periodic activities, which are automatically activated by the operating system at the specified rates. When the application consists of many concurrent tasks, each control activity may experience delay and jitter, which depend on several factors, including the scheduling algorithm running in the kernel, the overall workload, the task parameters, and the task interactions. If not properly taken into account, delays and jitter may degrade the performance of the system and even jeopardize its stability. In this paper, we evaluate three methodologies for reducing the jitter in control tasks: the first one consists of forcing the execution of inputs and outputs at the period boundaries, so trading jitter with delay; the second method reduces jitter and delay by assigning tasks shorter deadlines; whereas, the third method relies on non preemptive execution. We compare these techniques by illustrating examples, pointing out advantages and disadvantages, and evaluating their effects in control applications by simulation. It is found that the deadline advancement method gives the better control performance for most configurations.
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| 7. |
- Castañé, Rosa, et al.
(författare)
-
Resource Management for Control Tasks Based on the Transient Dynamics of Closed-Loop Systems
- 2006
-
Konferensbidrag (refereegranskat)abstract
- This paper presents a resource management strategy for control tasks that maximizes control performance within the available resources by readjusting the task periods at run-time. A feedback scheduler is used to determine on-line the optimal task periods considering the response over a finite time horizon of the plants controlled by arbitrary linear control laws. We show how this problem can be expressed as an optimization problem, where the objective function relates the sampling periods to the transient responses of the controlled plants, and where restrictions are based on EDF schedulability constraints. For the general case, the solution of the optimization problem is computationally expensive, and thus, an approximate procedure to be executed on-line has been developed. We present simulation results that validate the presented approach.
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| 8. |
- Cervin, Anton, et al.
(författare)
-
Analysis of Overrun Strategies in Periodic Control Tasks
- 2005
-
Ingår i: Proceedings of the 16th IFAC World Congress. - 008045108X
-
Konferensbidrag (refereegranskat)abstract
- The paper considers period overruns in control tasks with variationsin execution time (or response time). A simple model is used, wherethe input and output operations are assumed to be time-triggered,and the execution-time distribution of the task is assumed to beknown. Three overrun strategies, called Abort, Skip, andQueue, are modeled as discrete-time jump linear systems and areanalyzed with regard to control performance. The analysis isexemplified on an integrator process. It is argued that the Skipstrategy has good performance, is easy to analyze, and is simple toimplement in real-time operating systems. Some extensions to moredynamic models are also given.
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| 9. |
- Cervin, Anton, et al.
(författare)
-
Control loop timing analysis using TrueTime and Jitterbug
- 2006
-
Ingår i: 2006 IEEE Conference on Computer Aided Control System Design, 2006 IEEE International Conference on Control Applications, 2006 IEEE International Symposium on Intelligent Control. - 0780397975 ; , s. 290-295
-
Konferensbidrag (refereegranskat)abstract
- A modern control system is typically implemented as a multitasking software application executing in a real-time operating system. If the computer load is high, the controller will experience delays and jitter, which in turn degrade the control performance. Arguing for an integrated design approach, the paper describes two computer tools for implementation-aware control analysis: TrueTime and Jitterbug. An example is given where the tools are used together to evaluate the performance of various control task implementations
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| 10. |
- Cervin, Anton, et al.
(författare)
-
Control-Scheduling Codesign of Real-Time Systems: The Control Server Approach
- 2005
-
Ingår i: Journal of Embedded Computing. - 1740-4460. ; 1:2, s. 209-224
-
Tidskriftsartikel (refereegranskat)abstract
- The paper presents the control server, a real-time schedulingmechanism tailored to control and signal processing applications. Acontrol server creates the abstraction of a control task with aspecified period and a fixed input-output latency shorter than theperiod. Individual tasks can be combined into more complexcomponents without loss of their individual guaranteed fixed-latencyproperties. I/O occurs at fixed predefined points in time, at whichinputs are read or controller outputs become visible. The controlserver model is especially suited for codesign of real-time controlsystems. The single parameter linking the scheduling design and thecontroller design is the task utilization factor. The proposedserver is an extension of the constant bandwidth server, which isbased on the earliest-deadline-first scheduling algorithm. Theserver has been implemented in a real-time kernel and has also beenvalidated in control experiments on a ball and beam process.
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| 11. |
- Cervin, Anton, et al.
(författare)
-
On Limit Cycles in Event-Based Control Systems
- 2007
-
Ingår i: 46th IEEE Conference on Decision and Control, 2007. ; , s. 1947-1952
-
Konferensbidrag (refereegranskat)abstract
- Event-based control is a promising alternative to time-triggered control, especially for systems with limited computation and communication capacities. In the paper, the architecture of a general structure for event-based control is presented. The resulting system has many interesting properties. For instance, a constant load disturbance will typically make the process output oscillate according to a stable limit cycle. Necessary conditions for the limit cycle are given and its local stability is analyzed. Finally, a simple way to achieve integral action based on times between events is proposed.
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| 12. |
- Cervin, Anton, et al.
(författare)
-
Optimal on-line scheduling of multiple control tasks: A case study
- 2006
-
Ingår i: Proceedings - Euromicro Conference on Real-Time Systems. - 1068-3070. ; 2006, s. 141-150
-
Konferensbidrag (refereegranskat)abstract
- We study the problem of dynamically scheduling a set of state-feedback control tasks controlling a set of linear plants. We consider an on-line non-preemptive scheduling policy that is optimal in the sense that it minimizes a quadratic performance criterion for the overall system. The optimal scheduling decision at each point in time is a function of the states of the controlled plants. To be able to solve the scheduling problem for realistic examples, we use the technique of relaxed dynamic programming to compute suboptimal solutions with error bounds. The approach is compared to earlier approaches in a case study involving simultaneous control of one ball-and-beam process and two DC-servo processes. We also show how the scheduling policy can be modified to allow for background tasks to execute when the need for control is small.
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| 13. |
- Cervin, Anton, et al.
(författare)
-
Scheduling of Event-Triggered Controllers on a Shared Network
- 2008
-
Konferensbidrag (refereegranskat)abstract
- We consider a system where a number of independent, time-triggered or event-triggered control loops are closed over a shared communication network. Each plant is described by a first-order linear stochastic system. In the event-triggered case, a sensor at each plant frequently samples the output but attempts to communicate only when the magnitude of the output is above a threshold. Once access to the network has been gained, the network is busy for T seconds (corresponding to the communication delay from sensor to actuator), after which the control action is applied to the plant. Using numerical methods, we compute the minimum-variance control performance under various common MAC-protocols, including TDMA, FDMA, and CSMA (with random, dynamic-priority, or static-priority access). The results show that event-triggered control under CSMA gives the best performance throughout.
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| 14. |
- Cervin, Anton, et al.
(författare)
-
Simulation of Networked Control Systems Using TrueTime
- 2007
-
Konferensbidrag (refereegranskat)abstract
- This paper gives a brief introduction to the TrueTime simulator and then gives several examples on how TrueTime can be used to simulate networked control systems. Among the examples are time-triggered and event-based networked control and AODV routing in wireless ad-hoc networks.
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| 15. |
- Cervin, Anton, et al.
(författare)
-
Sporadic Control of Scalar Systems with Delay, Jitter and Measurement Noise
- 2008
-
Konferensbidrag (refereegranskat)abstract
- Event-triggered control is a promising alternative to time-triggered control, especially for severely resource-constrained networked embedded systems. Previous work has shown that event-triggered control can reduce both the output variance and the average control rate in scalar linear stochastic systems compared to time-triggered control. It has also been shown how a minimum inter-control interval can be imposed, hence the term ``sporadic control''. In this work we extend the analysis of event-triggered impulse control of first-order linear stochastic systems to handle general sampling intervals and minimum inter-control intervals, control delay and control jitter, and measurement noise. The results show that the advantage of sporadic control remains also in these cases.
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| 16. |
- Cervin, Anton, et al.
(författare)
-
The Control Server Model for Co-Design of Real-Time Control Systems
- 2006
-
Ingår i: ARTES -- A network for Real-Time research and graduate Education in Sweden 1997--2006.
-
Bokkapitel (refereegranskat)abstract
- The paper presents the control server, a real-time scheduling mechanism tailored to control and signal processing applications. A control server creates the abstraction of a control task with a specified period and a fixed input-output latency shorter than the period. Individual tasks can be combined into more complex components without loss of their individual guaranteed fixed-latency properties. I/O occurs at fixed predefined points in time, at which inputs are read or controller outputs become visible. The control server model is especially suited for codesign of real-time control systems. The single parameter linking the scheduling design and the controller design is the task utilization factor. The proposed server is an extension of the constant bandwidth server, which is based on the earliest-deadline-first scheduling algorithm. The server has been implemented in a real-time kernel and has also been validated in control experiments on a ball and beam process.
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| 17. |
- Cervin, Anton, et al.
(författare)
-
Återkoppling mellan lärare och studenter ur ett reglertekniskt perspektiv
- 2006
-
Ingår i: 4:e Pedagogiska Inspirationskonferensen 2006. - 2003-3761 .- 2003-377X. ; 4
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Återkoppling är centralt för lärandeprocessen. Studenterna behöver få konstruktiv feedback på sina prestationer för att lärandet ska bli effektivt och lyckat. Återkoppling är även ett centralt begrepp inom reglertekniken, där man med hjälp av feedback kan få olika tekniska processer att bete sig på önskat sätt. Vi ställer oss frågan om vilka insikter man kan nå genom att analysera lärandesituationen ur ett reglertekniskt perspektiv.
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| 18. |
- Cervin, Anton, et al.
(författare)
-
Återkoppling som del i lärandeprocessen
- 2006
-
Ingår i: 4:e Pedagogiska Inspirationskonferensen 2006. - 2003-3761 .- 2003-377X. ; 4
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Återkoppling är centralt för lärandeprocessen. Flera aktuella rapporter har emellertid visat att studenterna vid LTH anser sig få alldeles för lite återkoppling på sina prestationer. Artikeln diskuterar olika former och metoder för återkoppling, studenternas förväntningar på mängden återkoppling samt teori kring lärande och återkoppling.
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| 19. |
- Farias, Gonzalo, et al.
(författare)
-
Interactive Real-Time Control Labs with TrueTime and Easy Java Simulations
- 2007
-
Konferensbidrag (refereegranskat)abstract
- This paper presents the development of interactive real-time labs using TrueTime and Easy Java Simulations. TrueTime is a freeware Matlab/Simulink based tool to simulate real-time control systems, and Easy Java Simulations allows rapid creation of interactive simulations in Java. Authors can use TrueTime to develop the simulations of a real-time control system, and then move to Easy Java Simulations to link the system and create the graphical user interface which provides the visualization and user interaction. The combination of these tools brings together the best of them.
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| 20. |
- Farias, Gonzalo, et al.
(författare)
-
Multitasking Real-Time Control Systems in Easy Java Simulations
- 2008
-
Konferensbidrag (refereegranskat)abstract
- The paper presents the development of interactive real-time control labs using Easy Java Simulations (Ejs). Ejs is a free software tool that allows rapid creation of interactive simulations in Java. A new TrueTime-based kernel has been designed in Ejs in order to create multitasking real-time system simulations as well as soft real-time applications. The main features of these new capabilities are presented.
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| 21. |
- Henningsson, Toivo, et al.
(författare)
-
Comparison of LTI and Event-Based Control for a Moving Cart with Quantized Position Measurements
- 2009
-
Konferensbidrag (refereegranskat)abstract
- Traditional linear time-invariant (LTI) control design assumes that measurements are taken at regular time intervals and have independent additive noise. A common practical case that violates this assumption is the use of encoders that give quantized position measurements; when the quantization is appreciable the measurement noise is far from LTI. This paper develops a simple event-based controller based on simplifying a joint maximum a posteriori estimator, which is applied to a moving cart with quantized position measurements. The payoff for implementing the somewhat more complex event-based controller is to drastically reduce the effect of quantization noise in the experiments. A sequence of simpler (LTI) to better adapted controllers are described and compared according to experimental performance and implementation complexity. Implementation issues on the microcontroller are discussed.
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| 22. |
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| 23. |
- Henningsson, Toivo, et al.
(författare)
-
Sporadic event-based control of first-order linear stochastic systems
- 2008
-
Ingår i: Automatica. - : Elsevier BV. - 0005-1098. ; 44:11, s. 2890-2895
-
Tidskriftsartikel (refereegranskat)abstract
- The standard approach in computer-controlled systems is to sample and control periodically. In certain applications, such as networked control systems orenergy-constrained systems, it could be advantageous to instead use event-based control schemes. Aperiodic event-based control of first-order stochastic systems has been investigated in previous work. In any real implementation, however, it is necessary to have a well-defined minimum inter-event time. In this paper, we explore two such sporadic control schemes for first-order linear stochastic systems and compare the achievable performance to both periodic and aperiodic control. The results show that sporadic control can give better performance than periodic control in terms of both reduced process state variance and reduced control action frequency. (C) 2008 Elsevier Ltd. All rights reserved.
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| 24. |
- Henriksson, Dan, et al.
(författare)
-
Optimal On-line Sampling Period Assignment for Real-Time Control Tasks Based on Plant State Information
- 2005
-
Ingår i: Proceedings of the 44th IEEE Conference on Decision and Control and the 2005 European Control Conference. - 0780395689 ; , s. 4469-4474
-
Konferensbidrag (refereegranskat)abstract
- The paper presents a feedback scheduling strategy for multiple control tasks that uses feedback from the plant states to distribute the computing resources optimally among the tasks. Linear-quadratic controllers are analyzed, and expressions relating the expected cost to the sampling period and the plant state are derived and used for on-line sample-rate adjustments. In the case of minimum-variance control of multiple integrator processes, an exact expression for the optimal sampling periods is obtained. For the general case, an on-line optimization procedure is developed. The approach is exemplified on a set of controllers for first-order systems. The issues of computational delay and the choice of the feedback scheduler period are also discussed.
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| 25. |
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| 26. |
- Henriksson, Dan, et al.
(författare)
-
Tools for Real-Time Control Systems Co-Design
- 2006
-
Ingår i: ARTES -- A network for Real-Time research and graduate Education in Sweden 1997--2006.
-
Bokkapitel (refereegranskat)abstract
- A survey of four co-design tools for joint analysis, simulation, and design of computer-based control systems developed within the Swedish ARTES programme is presented. The tools allow simultaneous treatment of the control aspects and the computing and communication aspects of the control problems. The tools are Jitterbug and TrueTime developed at the Department of Automatic Control LTH, Lund University, and Aida and Xilo developed at the Division of Mechatronics, Department of Machine Elements, KTH.
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| 27. |
- Henriksson, Dan, et al.
(författare)
-
TrueTime: simulation of networked computer control systems
- 2006
-
Ingår i: Preprints. ADHS'06 2nd IFAC Conference on Analysis and Design of Hybrid Systems. ; , s. 272-273
-
Konferensbidrag (refereegranskat)abstract
- Computer-based control systems and networked control systems are hybrid systems where continuous time-driven dynamics and discrete event-driven dynamics interact. The temporal non-determinism introduced by computing and communication in the form of delays and jitter can lead to significant performance degradation. TrueTime is a MATLAB/Simulink-based simulation tool that takes a completely different approach. Using TrueTime it is possible to simulate the temporal aspects of multi-tasking real-time kernels and wired or wireless networks within Simulink together with the continuous-time dynamics of the controlled plant. TrueTime consists of a block library with a computer kernel block and wired and wireless network blocks. The blocks are variable-step, discrete, MATLAB S-functions written in C++. The kernel block executes user-defined tasks and interrupts handlers. The network blocks distribute messages between computer nodes according to a chosen network model. The blocks are connected with ordinary continuous-time Simulink blocks to form a real-time control system
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| 28. |
- Izosimov, Viacheslav, 1980-
(författare)
-
Scheduling and Optimization of Fault-Tolerant Embedded Systems
- 2006
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Safety-critical applications have to function correctly even in presence of faults. This thesis deals with techniques for tolerating effects of transient and intermittent faults. Reexecution, software replication, and rollback recovery with checkpointing are used to provide the required level of fault tolerance. These techniques are considered in the context of distributed real-time systems with non-preemptive static cyclic scheduling.Safety-critical applications have strict time and cost constrains, which means that not only faults have to be tolerated but also the constraints should be satisfied. Hence, efficient system design approaches with consideration of fault tolerance are required.The thesis proposes several design optimization strategies and scheduling techniques that take fault tolerance into account. The design optimization tasks addressed include, among others, process mapping, fault tolerance policy assignment, and checkpoint distribution.Dedicated scheduling techniques and mapping optimization strategies are also proposed to handle customized transparency requirements associated with processes and messages. By providing fault containment, transparency can, potentially, improve testability and debugability of fault-tolerant applications.The efficiency of the proposed scheduling techniques and design optimization strategies is evaluated with extensive experiments conducted on a number of synthetic applications and a real-life example. The experimental results show that considering fault tolerance during system-level design optimization is essential when designing cost-effective fault-tolerant embedded systems.
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| 29. |
- Johannesson, Erik, et al.
(författare)
-
Sporadic control of first-order linear stochastic systems
- 2007
-
Ingår i: Hybrid Systems: Computation and Control. 10th Internationa Conference, HSCC 2007. Proceedings (Lecture Notes in Computer Science Vol.4416). - Berlin, Heidelberg : Springer Berlin Heidelberg. ; 4416, s. 301-314
-
Konferensbidrag (refereegranskat)abstract
- The standard approach in feedback control systems is to sample and control periodically. For some applications, such as networked control systems or severely energy-constrained systems, it could be advantageous to instead use event-based control schemes. Aperiodic control (that is, event-based control with no specified minimum inter-event time) of first-order stochastic systems has been investigated in previous work. In any real implementation, however, it is necessary to have a well-defined minimum inter-event time. In this paper, we explore two such sporadic control schemes for first-order linear stochastic systems and compare the achievable performance to both periodic and aperiodic control. The results indicate that sporadic control can give better performance than periodic control in terms of reduced process state variance and control action frequency.
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| 30. |
- Kutil, Michal, et al.
(författare)
-
Balancing the Waiting Times in a Simple Traffic Intersection Model
- 2006
-
Konferensbidrag (refereegranskat)abstract
- We propose a novel dynamical model of a simple traffic intersection, where the state variables represent the queue lengths and the mean waiting times in the queues. Including the mean waiting times in the model allows for a more fair traffic control, where the waiting times of the individual vehicles in the various streets of the intersection are taken into account to some degree. The model is linearized and its parameters are estimated using real traffic data measured during one day in Prague. For the balancing of the waiting times, two different controllers are considered: a linear quadratic regulator and a nonlinear model predictive controller. The controllers are evaluated in simulations where real traffic data is used for the incoming flows.
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| 31. |
- Lluesma Camps, Manuel, et al.
(författare)
-
Jitter Evaluation of Real-Time Control Systems
- 2006
-
Konferensbidrag (refereegranskat)abstract
- The implementation of industrial control applications typically introduces complexities like sampling jitter and control jitter, which have usually not been considered at the design stage. Consequently, the system behaves in a non-periodic manner and the real performance is degraded with regard to the expected response. This paper proposes a hybrid task model to reduce the impact of the scheduling on control performance. For a large batch of typical plants, we analyze how sensitive a control system is to jitter when the sampling rate is slow or fast compared to the bandwidth of the system.
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| 32. |
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| 33. |
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| 34. |
- Reuterswärd, Philip, et al.
(författare)
-
TrueTime Network—A Network Simulation Library for Modelica
- 2009
-
Konferensbidrag (refereegranskat)abstract
- We present the TrueTime Network library for Modelica, developed within the ITEA2 project EUROSYSLIB. It allows for simulation of various network protocols and is intended for use within real-time networking. We describe some its features and discuss implementational issues. Since TrueTime Network is programmed in C, special attention is given to the how Modelica's external function interface is used. We also discuss briefly a future native Modelica implementation.
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| 35. |
- Robertz, Sven, et al.
(författare)
-
Memory-Aware Feedback Scheduling of Control Tasks
- 2006
-
Ingår i: Proceedings of the 11th IEEE Conference on Emerging Technologies and Factory Automation. - 0780397584 ; , s. 577-584
-
Konferensbidrag (refereegranskat)abstract
- This paper presents the incorporation of an auto-tuning real-time garbage collector into a feedback-based on-line scheduling system. The studied feedback scheduler is designed to dynamically adjust the sampling periods of a set of controller tasks in order to maximize the overall control performance. In the suggested approach, the memory management overhead is made explicit and taken into account by the feedback scheduler when scheduling the tasks. It is also described how priorities for memory allocations can be used to control the allocation rates of the application threads in order to optimize the trade-off between memory and CPU time usage. A case study, comparing theoretical analysis and simulated results support the feasibility of the approach.
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| 36. |
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| 37. |
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| 38. |
- Samii, Soheil, et al.
(författare)
-
Integrated scheduling and synthesis of control applications on distributed embedded systems
- 2009
-
Ingår i: Proceedings -Design, Automation and Test in Europe, DATE. - 9781424437818 ; , s. 57-62
-
Konferensbidrag (refereegranskat)abstract
- Many embedded control systems comprise several control loops that are closed over a network of computation nodes. In such systems, complex timing behavior and communication lead to delay and jitter, which both degrade the performance of each control loop and must be considered during the controller synthesis. Also, the control performance should be taken into account during system scheduling. The contribution of this paper is a control-scheduling co-design method that integrates controller design with both static and priority-based scheduling of the tasks and messages, and in which the overall control performance is optimized.
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| 39. |
- Samii, Soheil, et al.
(författare)
-
Quality-Driven Synthesis of Embedded Multi-Mode Control Systems
- 2009
-
Ingår i: DAC '09 Proceedings of the 46th Annual Design Automation Conference. - New York, NY, USA : IEEE Computer Society. - 9781605584973 ; , s. 864-869
-
Konferensbidrag (refereegranskat)abstract
- At runtime, an embedded control system can switch between alternative functional modes. In each mode, the system operates by using a schedule and controllers that exploit the available computation and communication resources to optimize the control performance in the running mode. The number of modes is usually exponential in the number of control loops, which means that all controllers and schedules cannot be produced in affordable design-time and stored in memory. This paper addresses synthesis of multi-mode embedded control systems. Our contribution is a method that trades control quality with optimization time, and that efficiently selects the schedules and controllers to be synthesized and stored in memory.
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| 40. |
- Torngren, Martin, et al.
(författare)
-
Tool supporting the co-design of control systems and their real-time implementation: current status and future directions
- 2006
-
Ingår i: 2006 IEEE Conference on Computer-Aided Control System Design, Vols 1 and 2. - 0780397975 ; , s. 269-276
-
Konferensbidrag (refereegranskat)abstract
- Control systems design has traditionally been treated separately from the design of its software and hardware implementation. The increasing use of embedded control in for example distributed, safety critical and mass-produced systems has caused an increasing need for the simultaneous consideration of the control system and its implementation platform during development To this end, there is a need for both theoretical contributions and supporting tools that assist designers in understanding and analyzing the intricate relationships between the qualities, such as control performance, robustness and cost, and design parameters related to control system and platform design. This paper explores issues in co-design. A number of representative tools are compared with the purposes of illustrating different approaches concerning the levels of abstraction, analysis vs. synthesis features, constraints addressed and usability features. A perspective to the co-design tools is also provided, where opportunities and challenges for future design environments are discussed.
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| 41. |
- Törngren, Martin, 1963-, et al.
(författare)
-
Tools supporting the co-design of control systems and their real-time implementation : Current status and future directions
- 2006
-
Ingår i: 2006 IEEE Conference on Computer-Aided Control System Design, Vols 1 and 2. - : IEEE Press. - 9780780397972 ; , s. 1173-1180
-
Konferensbidrag (refereegranskat)abstract
- Control systems design has traditionally been treated separately from the design of its software and hardware implementation. The increasing use of embedded control in for example distributed, safety critical and massproduced systems has caused an increasing need for the simultaneous consideration of the control system and its implementation platform during development. To this end, there is a need for both theoretical contributions and supporting tools that assist designers in understanding and analyzing the intricate relationships between the qualities, such as control performance, robustness and cost, and design parameters related to control system and platform design. This paper explores issues in co-design. A number of representative tools are compared with the purposes of illustrating different approaches concerning the levels of abstraction, analysis vs. synthesis features, constraints addressed and usability features. A perspective to the co-design tools is also provided, where opportunities and challenges for future design environments are discussed.
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| 42. |
- Årzén, Karl-Erik, et al.
(författare)
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Control and Embedded Computing: Survey of Research Directions
- 2005
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Ingår i: Proceedings of the 16th IFAC World Congress. - 008045108X
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Konferensbidrag (refereegranskat)abstract
- This paper provides a survey of the role of feedback control in embedded realtimesystems, presented in the context of a new EU/IST Network of Excellence, ARTIST2.The survey highlights recent research efforts and future research directions in the areasof codesign of computer-based control systems, implementation-aware embedded controlsystems, and control of real-time computing systems.
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| 43. |
- Årzén, Karl-Erik, et al.
(författare)
-
Holistic Simulation of Mobile Robot and Sensor Network Applications Using TrueTime
- 2007
-
Konferensbidrag (refereegranskat)abstract
- The RUNES project defines a complex road tunnel scenario involving multiple mobile robots navigating in sensor network environment. In this paper, a TrueTime simulation model of the tunnel scenario is developed. The TrueTime simulator allows concurrent simulation of the physical robots and their environment, the software in the nodes, the radio communication, the network routing, and the ultra-sound navigation system. The various models are described in detail, and some simulation results obtained from the complete model are presented.
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| 44. |
- Årzén, Karl-Erik, et al.
(författare)
-
Implementation-Aware Embedded Control Systems
- 2005
-
Ingår i: Handbook of Networked and Embedded Control Systems. - 0817632395
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Most embedded control systems have constrained computationalresources. This makes codesign of the control algorithms and thereal-time scheduling an interesting issue. There is also a strongtrend in the real-time community of moving away from the hardreal-time model. Hence, embedded controllers must be designed sothat they are aware of the resource constraints and timinguncertainty of the implementation platform. This paper discussestemporal determinism, design approaches, and codesign tools for suchsystems.
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