Regular Specifications of Resource Requirements for Embedded Control Software

For embedded control systems, a schedule for the allocation of resources to a software component can be described by an infinite word whose ith symbol models the resources used at the ith sampling interval. Dependency of performance on schedules can be formally modeled by an automaton (w-regular language) which captures all the schedules that keep the system within performance requirements. We show how such an automaton is constructed for linear control designs and exponential stability or settling time performance requirements. Then, we explore the use of the automaton for online scheduling and for schedulability analysis. As a case study, we examine how this approach can be applied for the LQG control design. We demonstrate, by examples, that online schedulers can be used to guarantee performance in worst-case condition together with good performance in normal conditions. We also provide examples of schedulability analysis

Anomalies in Scheduling Control Applications and Design Complexity

Today, many control applications in cyberphysical systems are implemented on shared platforms. Such resource sharing may lead to complex timing behaviors and, in turn, instability of control applications. This paper highlights a number of anomalies demonstrating complex timing behaviors caused as a result of resource sharing. Such anomalous scenarios, then, lead to a dramatic increase in design complexity, if not properly considered. Here, we demonstrate that these anomalies are, in fact, very improbable. Therefore, design methodologies for these systems should mainly be devised and tuned towards the majority of cases, as opposed to anomalies, but should also be able to handle such anomalous scenarios

Imunokromatografsko testiranje lateralnog toka (LFIA) čitača trake temeljeno na rasporedu i 8051 IP jezgri

Lateral flow immunochromatographic assay (LFIA) testing is essential for accurate detection and diagnoses of diseases and physical conditions. However, the existing LFIA strip reader equipped with high cost of hardware confines its simplicity and portability. Therefore, this study develops a simple, low cost LFIA strip reader comprising 4 major modules --- mechanical, optical, processing and control modules. The mechanical module pulls in and out the test strip automatically to be read by the optical module and the data processing module provides the test results by analyzing the data sent by the optical module. All the individual modules are controlled by a control module. To reduce the hardware budget and control complexity, a time-triggered cooperative (TTC) scheduler implemented on an 8051 IP core was chosen as control system. In addition, special, high sensitivity C- reactive protein (CRP) strips with 10 different concentrations were tested to evaluate the performance of the system. Further, a commercial ESEQuant lateral flow reader (QIAGEN, Germany) was tested as a comparative study. The test results show that the proposed reader was stable with a coefficient of variation (CV) factor within 3%. To test the qualitative performance of the system, each of the CRP concentration were examined for 10 times, which indicates that the system has a large dynamic detection range and good detection linearity (^2 = 0.998). In short, the proposed LFIA strip reader has high potential relative to existing readers, especially in simplicity and cost.Imunokromatografsko testiranje lateralnog toka (LFIA) nužno je za preciznu detekciju i dijagnozu oboljenja te psihičkih stanja. Međutim, postojeći LFIA opremljeni s hardverom visoke cijene limitiraju jednostavnost i prenosivost. Ovo istraživanje razvija jednostavni, niske cijene, čitač traka koji se sastoji od 4 glavna dijela - mehanički, optički, procesni i upravljački. Mehanički modul povlači testnu traku automatski kako bi optički modul mogao čitati. Procesni modul analizira podatke dobivene s optičkog čitača. Svaki modula upravlja se upravljačkim modulom. Vremensko ovisno kooperativni raspored implementiran je na 8051 IP jezgri kako bi se smanjili računski zahtjevi. Dodatno, visoko osjetljiva CRP traka s deset različitih koncentracija korištena je u svrhe evaluacije sustava. Rezultati su uspoređeni s komercijalnim čitačem lateralnog toka ESEQuant (QIAGEN, Njemačka). Rezultati pokazuju da je predložena metoda stabilna s koeficijentom varijacije unutar 3%. Kako bi se kvalitativno testirao sustav, svaka od CRP koncentracija testirana je deset puta, što ukazuje da sustav veliki dinamički raspon detekcije te dobru linearnost detekcije (R^2 = 0.998). Predloženi LFIA čitač traka ima dosta potencijala u usporedbi s postoječim čitačima, posebno u smislu jednostavnosti i cijene

Time-triggered Implementations of Dynamic Controllers

Bridging the gap between model-based design and platform-based implementation is one of the critical challenges for embedded software systems. In the context of embedded control systems that interact with an environment, a variety of errors due to quantization, delays, and scheduling policies may generate executable code that does not faithfully implement the model-based design. In this paper, we show that the performance gap between the model-level semantics of linear dynamic controllers, e.g. the proportional-integral-derivative (PID) controllers, and their implementation-level semantics can be rigorously quantified if the controller implementation is executed on a predictable time-triggered architecture. Our technical approach uses lifting techniques for periodic, time-varying linear systems in order to compute the exact error between the model semantics and the execution semantics. Explicitly computing the impact of the implementation on overall system performance allows us to compare and partially order different implementations with various scheduling or timing characteristics