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Our work discusses a conjecture formulated for supporting the stability analysis of polytopic systems, within the context of enlarging our explorations from real to complex statespace models. This conjecture refers to a property of the spectral radius that is true for real matrices and we assumed to be adaptable to complex matrices. Our presentation is organized as an extensive case study aiming to...
In this paper a one degree of freedom (DOF) force augmenting device (FAD) is presented. A laboratory set-up has been built and some tests of the interaction between the FAD and a user were performed. The stability of the closed loop system is essential for the performance of the FAD. The FAD by itself is a stable device, but what is important is to assure the stability of the interaction between the...
Given a generalized system whose transfer matrix function may be improper or may be polynomial, we provide necessary and sufficient conditions under which a minimal factorization does exist. The conditions are formulated in terms of deflating subspaces of pencils related to a special type of realisation, called centered, which allows to efficiently cater for poles and/or zeroes at infinity.
In this paper we represent a decentralised control LTI system by a weighted directed graph. Then we derive sufficient conditions for such systems with decentralised fixed modes (DFMs) to be stabilisable. The sufficient conditions relate to whether the DFMs are quotient fixed modes (QFMs) of the system and thus can or cannot be shifted by any type of controller. It is shown that a DFM is a QFM when...
The paper proposes two estimation methods for the spectral radius of a complex interval matrix. These methods exploit different properties of the interval matrix and construct distinct numerical approaches, so that their results dispute, from case to case, the precision of the estimation. This complementarity of the two methods recommends their parallel use in practical applications, allowing the...
This paper presents the enhancement of the Sniper multicore / manycore simulator with thermal measurement possibilities using the HotSpot simulator. We present a plugin that interacts with Sniper to retrieve simulation data (integration areas and power consumptions) and calls HotSpot to compute the corresponding thermal results. The plugin also builds a two dimensional floorplan for the simulated...
This paper presents a series of Built-In Self-Test architectures designed for the IDEA NXT family of crypto-algorithms implemented in crypto-chips. The proposed error-detection schemes are capable of verifying the integrity of the crypto-chip in an autonomous, non-concurrent manner. One of the testing solutions consists of stimulating the algorithm with test vectors generated by the IDEA NXT core...
In most of the safety-critical areas, including systems, avionics, automotive, and factory automation, the use of real-time time-trigger schedulers are encouraged due to their characteristics that does not allow interference to take place between safety-critical and non-critical components. Depending on the field where these types of schedulers are used, they can be categorized as preemptive or non-preemptive...
This paper presents the sensorial system for structure of a backbone hyper-redundant arm with an electro-pneumatically system for position control. A system of cables actuated by DC motors is used for bending. Control system is based on a PIC microcontroller. The position of the robot can be obtained by bending it with the cables and by blocking the position of the elements we need, using the electro-pneumatically...
An important issue related to Real-Time Operating Systems is the handling of interrupts, timers, mutexes, watchdog timers, synchronization and communication directives as unitary events. In order to obtain a predictable response time for the different types of events that occur simultaneously, it is necessary to have a prioritization mechanism for them. Therefore, this paper proposes a hardware mechanism...
Magnetic levitation systems are widely used in practice and especially as a research topic due to their nonlinear and unstable characteristics. In this paper, two rarely used control algorithms for unstable systems are proposed: a special type of a fractional order controller and an IMC (Internal Model Control) based controller. The two control algorithms are compared and tested on an experimental...
This paper describes one novel design procedure for acquiring an optimal fractional PID (FPID) controller that rejects load disturbance under constraints on robustness and performance. The parameters of FPID controller have been tuned by using particle swarm optimization (PSO). FPID, apart from conventional gains kp, ki and kd, has two more parameters α and β to be optimized, being the non-integer...
Mechatronic systems are usually described by integer-order state equations. Based on these integer-order models, conventional integer-order PID controllers are designed. In this paper, we use a Steward platform (ball and plate system) with different balls to investigate the robustness of the fractional-order controller against the mass changes of the ball. The closed-loop performances of the fractional-order...
This paper is about a hierarchical structure with an event-based supervisor in a higher level and a fractional-order proportional integral (FOPI) in a lower level applied to a wind turbine. The event-based supervisor analyzes the operation conditions to determine the state of the wind turbine. This controller operate in the full load region and the main objective is to capture maximum power generation...
The work presents two measures of complexity, fractal dimension and lacunarity, in order to raise the precision in breast cancer diagnosis. A set of 40 cases of mammograms from patients corresponding to both benign (24 images) and malignant tumors (16 images) were analyzed. To improve the diagnostic process we proposed a method that combines the two fractal characteristics. For the processing of mammograms...
When Ant System algorithm is used to solve combinatorial optimization problems with precedence constraints, the computation of components list that can be used to extend the current partial solution is time consuming. For every component, the algorithm tests if the precedence constraints are met. In this work, a treatment list of components is proposed, aiming to avoid the test of precedence constraints...
This paper considers the problem of computing a Lyapunov function for nonlinear discrete-time systems. The proposed solution is systematic and consists of two steps. First, a pseudo-Lyapunov function, called finite-step Lyapunov function, is computed by solving a finite dimensional nonlinear optimization problem. Then, a recent converse theorem is employed, which gives an explicit construction of...
The linear quadratic optimal control problem for time invariant systems is presented. The problem with Unite final time and fixed end-point is considered. The study takes into account the influence of the time variant perturbations in optimal control law implementation. The applicability of the proposed algorithm is illustrated by simulation tests.
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