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Service-oriented architectures become more and more important in connecting devices with each other. The main advantages of service-oriented architectures are higher abstraction level and interoperability of devices. In this field Web services become the most important standard for communication between devices. But this upcoming technology is only available on powerful devices. Embedded hardware...
The necessity to improve the current automation concepts for cost reduction in plant engineering represents a widely discussed problem. Although research has been developing solutions for this problem area for quite some time on the basis of decentralized automation concepts, industrial companies have been showing reluctance concerning their broad application in practice. This contribution discusses...
This work presents a supervisory fault tolerant system for hybrid productive systems based on Bayesian networks and OO-DPT (Object-Oriented Differential Predicate-Transition Nets) formalism. Here, systems are characterized as hybrid when they contain continuous and discrete variables and both are fundamental to describe the systemspsila dynamics. The present approach introduce a procedure for the...
This paper discusses the introduction of mechanisms to adapt commercial powered wheelchairs in order to facilitate its driving by quadriplegic people with reduced strength. Several models of operation are proposed and the most promising, at the moment, called legacy adapted mode, is detailed. A part of the formal operation model is presented. The model is then used in the STAGE simulator, not only...
Networked control systems (NCSs) are a very interesting solution to several control problems, and the definition of metrics and procedures for the design of more efficient NCSs is an open research field. This paper analyzes two evaluation metrics currently available: the quality-of-control and the jitter margin. This analysis will be used in further studies at the Federal University of Santa Catarina,...
Field-programmable gate arrays provide a flexible and easy-to-configure implementation platform that supports the development of tamper-proof networked embedded systems. Many of these systems employ the Advanced Encryption Standard algorithm in order to achieve a secure mode of operation. Since this algorithm is of a high computational complexity, this paper utilizes various hardware-software co-design...
Elliptic curve cryptography (ECC) is a very promising cryptographic method, offering the same security level as traditional public key cryptosystems (RSA, El Gamal) but with considerably smaller key lengths. To increase the performance of an EC Cryptosystem, dedicated hardware is employed for all EC point operations. However, the computational complexity and hardware resources of an Elliptic Curve...
We investigate the implementation of supervisors generated by symbolic BDD-based Discrete Controller Synthesis (DCS). The implementation technique proposed is able to solve both control non-determinism and the structural incompatibility introduced by symbolic DCS. We highlight and illustrate interesting structural properties of the supervisor implementation. Our technique is illustrated on a reallife...
The automation of plants and machines is becoming more and more complex due to the extensive usage of intelligent field devices as for instance programmable actuators and sensors. The graphical programming languages used are typically for the automation domain, and control applications tend to be become increasingly complex which results in higher engineering costs for establishment and maintenance...
In this work in progress practice the use of Java programming language, and a Java library called ProActive, for developing distributed control systems is presented. The authors are developing a middleware which provide services for communicating several tools presented in scientific and industrial facilities like EPICS and Labview. The first efforts are focused on the communication scheme between...
In wireless sensor networks (WSNs) used in monitoring applications, the need to provide real-time traffic with an appropriate QoS typically clashes with the energy consumption constraints of the nodes, which have to work for long periods without the possibility of replacing their batteries. When both energy and QoS constraints are present, the role of topology control mechanisms is fundamental. This...
The aim of this paper is to investigate on the closed loop welding controller of a rapid manufacturing shaped metal deposition (SMD) process. SMD was developed and patented by Rolls-Royce in order to produce mechanical parts directly from a CAD model. The paper describes a deep investigation upon the welding dynamics and parameters in order to develop an SMD automatic controller. An SMD plant has...
Wireless sensor networks are useful for many reasons, but they add at least two new issues to the Extended Kalman Filtering problem. First, they can be a further cause of divergence, as the information they send could not reach the filter. Second, batteries consumption must be taken into account: this leads to the need for a policy of querying, at each time instant, only a few sensors. In this paper...
The present paper evaluates meta-heuristic approaches to solve a soft drink industry problem. This problem is motivated by a real situation found in soft drink companies, where the lot sizing and scheduling of raw materials in tanks and products in lines must be simultaneously determined. Tabu search, threshold accepting and genetic algorithms are used as procedures to solve the problem at hand. The...
This paper presents a neuro-fuzzy implementation of the delay compensator to reduce the variable sampling to actuation delay effects in distributed control systems. The delay compensator approach proposed the addition of a compensator to an existing distributed system in order to overcome the control performance degradation that results from the variable sampling to actuation delay that characterizes...
Almost all automatic repeat request (ARQ) protocols rely on checksums to let the receiver decide about the presence of transmission errors. If the checksum is wrong a retransmission takes place. In case of transmission errors often only a few bits are erroneous, but in a frame retransmission all bits are transmitted again, including the correct ones. This paper introduces the so-called intermediate...
One of the main drawbacks of the Smith predictor (SP) for controlling systems affected by external delays is that the resulting performance relies on the accuracy of the knowledge regarding such delays. Thus, as the mismatch between the true value of the delay and the nominal one employed for control purposes increases the closed loop performance deteriorates accordingly. This point is particularly...
This paper describes the use of evolutionary algorithms to find an optimal solution for the parameters of an impedance controller represented as an artificial neural network (ANN). An impedance controller with force tracking capabilities has been evolved using evolutionary strategies which control the forces between a robotic manipulator and the environment. Simulation results show the controllerpsilas...
The following article introduces OMaCS (online management and control system), a multiple client single server software system for the control of crystal growth systems (e.g. multi-zone furnaces). OMaCS has especially been tuned to the needs of the process thus allowing quick and efficient co-operating of different user groups. The software is a flexible system applicable for different types of growing...
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