Diagnosis of transient faults in quantised systems

This paper concerns the diagnosis and identification of faults that occur in systems where signals can only be measured through a quantiser. A qualitative model is used that represents the discrete-event behaviour of the quantised system. Three different diagnostic algorithms are presented for determining the fault probabilities, the first concerning faults currently affecting the system and the second determining the probabilities that faults occurred at any time in the past. The third algorithm is based on the assumption that the faults occurred only during a time interval in the past. Due to this assumption, the algorithm is applicable for continuously running processes and for the online identification of transient faults. The approach is illustrated by an example of a manufacturing cell.     

Enhanced continuous valued Q-learning for real autonomous robots

A parallel-jaw gripper is a very useful tool for robot manipulation tasks due to its simple mechanism and control. This fact limits the range of successful grasps it can undergo, and also makes it unfeasible under uncertainties. Thus, it is desirable to improve its dexterity and manipulability. In this paper, we propose a new design of a two-fingered parallel gripper that utilizes rolling at the contacts for object repositioning and reorientation, aimed at effective firm grasps. We name it the scrollic gripper, an acronym for synchronously closing with rolling constraints. At first, the background to utilize the rolling constraints is described. Then, grasping and manipulation of the gripper are discussed. In grasp acquisition, we propose a quality function for evaluating grasp stability. The sophisticated hardware and functioning for the scrollic gripper consist, basically, on implementation of an additional degree-of-freedom to the conventional parallel-jaw gripper, leading to grasp acquisition and secure grasping.     

Non-asymptotic stability of complex valued differential systems†

Sufficient conditions for the existence of orbital motion and non-asymptotic, non-orbital motion in the solutions of constant coefficient complex variable differential equations are obtained through Liapunov's direct method. Matrix analogues of those conditions assure the corresponding type of motion of interconnected systems whose complex coefficient matrices are simultaneously diagonalizable.     

A continuity property for the filter associated to Hilbert-space valued systems

The purpose of this paper is to study the continuity with respect to the trajectory of the observation process for the filter associated to nonlinear filtering problems when both the signal and the observation processes evolve on real separable Hilbert spaces.     

Simulating continuous fuzzy systems

In previous studies we concentrated on utilizing crisp, numeric simulation to produce discrete event fuzzy systems simulations. Then we extended this research to the simulation of continuous fuzzy systems models. In this study, we continue our study of continuous fuzzy systems using crisp continuous simulation. Consider a crisp continuous system whose process of evolution depends on differential equations. Such a system contains a number of parameters that must be estimated. Usually point estimates are computed and used in the model. However, these point estimates typically have uncertainty associated with them. We propose to incorporate uncertainty by using fuzzy numbers as estimates of these unknown parameters. Fuzzy parameters convert the crisp system into a fuzzy system. Trajectories describing the behavior of the system become fuzzy curves. We will employ crisp continuous simulation to estimate these fuzzy trajectories. Three examples are discussed.     

Stability of continuous hybrid systems

The stationary state of a continuous hybrid system is analyzed for stability using the method of Lyapunov functions. Sufficient conditions of stability and instability are established. These conditions are constructive and can easily be calculated. __________ Translated from Kibernetika i Sistemnyi Analiz, No. 2, pp. 123–128, March–April 2007.     

Extremum control of continuous systems

An extremum control system is considered which consists of the following in cascade: an integrator, a function of the parabolic type and a first-order system. A method is presented for determining and maintaining the extremum in the presence of disturbances. The method suggested consists of perturbing the system input, then using the discontinuities in an appropriate derivative of the system output to determine the extremum. The advantage gained is speed in identifying the extremum independent of the initial conditions. Analog and digital computer results are given.     

Neural network based on adaptive resonance theory with continuous training for multi-configuration transient stability analysis of electric power systems

This work presents a methodology to analyze electric power systems transient stability for first swing using a neural network based on adaptive resonance theory (ART) architecture, called Euclidean ARTMAP neural network. The ART architectures present plasticity and stability characteristics, which are very important for the training and to execute the analysis in a fast way. The Euclidean ARTMAP version provides more accurate and faster solutions, when compared to the fuzzy ARTMAP configuration. Three steps are necessary for the network working, training, analysis and continuous training. The training step requires much effort (processing) while the analysis is effectuated almost without computational effort. The proposed network allows approaching several topologies of the electric system at the same time; therefore it is an alternative for real time transient stability of electric power systems. To illustrate the proposed neural network an application is presented for a multi-machine electric power systems composed of 10 synchronous machines, 45 buses and 73 transmission lines.     

MPC for continuous piecewise-affine systems

A large class of hybrid systems can be described by a max–min-plus-scaling (MMPS) model (i.e., using the operations maximization, minimization, addition and scalar multiplication). First, we show that continuous piecewise-affine systems are equivalent to MMPS systems. Next, we consider model predictive control (MPC) for these systems. In general, this leads to nonlinear, nonconvex optimization problems. We present a new MPC method for MMPS systems that is based on canonical forms for MMPS functions. In case the MPC constraints are linear constraints in the inputs only, this results in a sequence of linear optimization problems such that the MPC control can often be computed in a much more efficient way than by just applying nonlinear optimization as was done in previous work.     

Decomposition-based continuous control of mechanical systems

For Lagrangian dynamical systems with inexactly known parameters, a continuous feedback control is constructed using ideas of the decomposition method on the major segment of the trajectory and linear feedbacks with the coefficients depending on the phase variables in the vicinity of the terminal state. It is supposed that the matrix of kinetic energy of the system is close to a constant matrix in the motion domain and that the system is affected by uncontrollable bounded disturbances. The proposed controls make it possible to steer the system from an arbitrary initial state into a given terminal state in a finite amount of time using generalized forces that are bounded by magnitude. An upper estimate on the total time of system motion is given and techniques for its reduction are described. The efficiency of the proposed algorithms is demonstrated by the numerical simulation of the dynamics of some simple mechanical systems.     

Stability of a matrix polynomial in continuous systems

Two sufficient conditions under which the roots of the determinant of a given (m times m) matrix polynomial ofnth order lie in the open left-half plane have been obtained. The first condition is given in terms of the positive definiteness of an (mn times mn) symmetric matrix, while the second condition is given in terms of the positive definiteness of an (m times m) matrix that is a function ofs, Res leq 0. These conditions are represented in terms of rational functions of the coefficient matrices of the given matrix polynomial. Therefore, the explicit computation of the determinant polynomial is not required.     

Digital simulation of continuous feedback systems

Trapezoidal convolution derives general and special discrete equivalents of continuous feedback systems in a straightforward manner. A critique of two other published discretizations is presented.     

Weak continuous measurements of multiqubits systems

In this review we summarize our recent experiments on the investigation on superconducting qubits. Instead of strong projective measurement used by other groups in their first pioneering experiments we have proposed and realized a weak continuous readout which belongs to the class of quantum non-demolition measurements. Moreover, our scheme enables to measure a superconducting qubit at the so called sweet (or magic) point where a qubit is in a superposition of two classical states and its sensitivity to external noise is minimized. In this scheme, which is widely used nowadays, the superconducting oscillator coupled to superconducting qubit is used as a detector of the qubit’s state. Such system is analogue to a system of a single atom interacting with photons in a cavity, which allows to study quantum electrodynamics in artificial macroscopic systems. Pushing this analogy we demonstrate Sisyphus cooling and amplification caused by energy exchange between an oscillator and a flux qubit. Using the Sisyphus effect we show consistency between the adiabatic weak continuous measurement in the ground state and the spectroscopic measurement. This allows us to characterize the more complicated system of coupled qubits by making use of the same method. We have realized and studied fixed ferromagnetic, antiferromagnetic as well as tunable qubit–qubit coupling. We argue that ground state measurements can be used for characterization of entangled states in coupled flux qubits.     

Robust stabilization of continuous indeterminate systems

The system of an arbitrary order with one scalar control is considered. It is assumed that coefficients of the system and vectors of distribution of control are bounded and are functionals of an arbitrary character. With the aid of the Lyapunov function in a quadratic form with the constant Jacobian matrix of coefficients of a special form, the conditions for bounds of a change of the coefficients are obtained, in the fulfillment of which the linear stationary control by the state is synthesized. In this control, the system becomes exponentially stable on the whole.     

Model-based diagnosis of continuous static systems

Research on model-based diagnosis of technical systems has grown enormously in the last few years, producing new basic tools, new algorithms and also some applications. However, the majority of research has dealt with systems described by variables ranging in discrete domains (e.g., digital circuits), and only few attempts have been made at applying such techniques to continuous domains. Continuous systems are characterized by additional problems, such as the unavoidable sensor errors and the need for using more complex models which may consist of simultaneous non-linear equations. The distinctive feature of the approach we present in this paper is the integration of techniques well known in the field of numerical analysis and statistics (e.g., the solution of non-linear systems and the error propagation) with a dependency-recording technique based on ordering the equations and the variables of the model.     

Digitalization of existing continuous control systems

The problem of converting existing continuous-data control systems into digital control systems is considered. The objective of this paper is to develop a computer-aided method for synthesizing the pulse-transfer function of the digital controller. This is done by matching the frequency response of the digital control system to that of the continuous system with a minimum weighted mean-square error. Formulas for computing the parameters of the digital controller are obtained as a result. The design technique is illustrated aith a numerical example, and a comparison with previous methods is also presented.     

Robust absolute stability of continuous systems

The problem of stability of continuous-time nonlinear systems with nonparametric uncertainty of a linear part and sector uncertainty of its nonlinear part is considered. The proposed robust stability criterion is a natural extension of the circle criterion for absolute stability. The situation with the Popov criterion is also discussed; it is demonstrated to be nonrobust for perturbations of a linear part, bounded in H^∞ norm.     

连铸板坯三维瞬态温度场的软件模拟实现

连铸过程实际是一个凝固传热过程.连铸过程中的铸坯温度分布及其变化对于产品质量是非常重要的,人们不断地研究和调整连铸工艺参数.目的就是为了获得理想的温度分布.近年来广大研究者对铸坯凝固的温度场进行了大量深入细致的研究.并开发出了很多温度场模拟的模型和软件.但大都是二维的,只能用于离线工况的静态模拟,不能有效模拟连铸过程中经常存在的非稳态情况.本文建立了板坯连铸传热过程的三维非稳态数学模型,可以实时的反映不同连铸工艺参数对铸坯温度场的瞬态影响,并将计算结果与实测结果进行了比较来说明模型的准确性.为制定合理的二冷制度,和确定动态轻压下的压下位置提供可靠的依据.