A recursive scheme is derived for calculation of the expansion coefficients of a known system transfer function into a generalized orthonoimal rational basis. The inherent structure of the basis functions leads to a c...
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A recursive scheme is derived for calculation of the expansion coefficients of a known system transfer function into a generalized orthonoimal rational basis. The inherent structure of the basis functions leads to a computationally efficient method, which needs the solution of a low-dimensional Sylvester equation at each step. The method is demonstrated with a brief example. Possible applications are also discussed.
This paper deals with the problem of improving the parameter identifiability properties of robot model. Through the exploitation of the upper-triangular structure of the information matrix, the estimation of the invar...
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This paper deals with the problem of improving the parameter identifiability properties of robot model. Through the exploitation of the upper-triangular structure of the information matrix, the estimation of the invariants (masses, inertias, etc). which usually requires at the most 11 n parameters for a robot manipulator with n degrees of freedom (DOF), can be performed link by link in a sequential manner by n algorithms of size n i where Σ n i is smaller than 11n. Optimization of the robot trajectories seeking to improve parameters identifiability can be simplified. A study case is presented of a 4-DOF robot used for nuclear maintenance having three co-linear axes. Instead of having a single-pass algorithm of dimension 12, the method yields a 4-passes estimation algorithm with a parameter vector dimension of 4, 4, 3 and 1 respectively for each pass. This method enhances the numerical algorithm conditioning and facilitates the selection of a high excited identification sequence improving the parameter identifiability.
The problem of the identification of Hammerstein and Wiener models is considered in this paper. The suggested approach in this paper utilizes the spectral magnitude matching method that minimizes the sum squared error...
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The problem of the identification of Hammerstein and Wiener models is considered in this paper. The suggested approach in this paper utilizes the spectral magnitude matching method that minimizes the sum squared error between the spectral magnitudes - evaluated for a number of short-time frames - of the measured output signal of the nonlinear system and the output signal of the nonlinear model. The coefficients of Hammerstein and Wiener models are estimated using the generalized Newton iterative algorithm. Simulation results show that the suggested approach gives very good results especially for moderate and high signal to noise ratios.
We address the problem of approximating the posterior probability distribution of the fixed parameters of a state-space dynamical system using a sequential Monte Carlo method. The proposed approach relies on a nested ...
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We address the problem of approximating the posterior probability distribution of the fixed parameters of a state-space dynamical system using a sequential Monte Carlo method. The proposed approach relies on a nested structure that employs two layers of particle filters to approximate the posterior probability measure of the static parameters and the dynamic state variables of the system of interest, in a vein similar to the recent “sequential Monte Carlo square” (SMC2) algorithm. However, unlike the SMC2 scheme, the proposed technique operates in a purely recursive manner. In particular, the computational complexity of the recursive steps of the method introduced herein is constant over time. We analyse the approximation of integrals of real bounded functions with respect to the posterior distribution of the system parameters computed via the proposed scheme. As a result, we prove, under regularity assumptions, that the approximation errors vanish asymptotically in Lp (p≥1) with convergence rate proportional to 1N+1M, where N is the number of Monte Carlo samples in the parameter space and N×M is the number of samples in the state space. This result also holds for the approximation of the joint posterior distribution of the parameters and the state variables. We discuss the relationship between the SMC2 algorithm and the new recursive method and present a simple example in order to illustrate some of the theoretical findings with computer simulations.
In this paper an extension of the Newton - Euler models to the case of flexible robots is achieved. Today, such models are mainly used for rigid manipulators. In this case they give the best results to solve the simul...
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In this paper an extension of the Newton - Euler models to the case of flexible robots is achieved. Today, such models are mainly used for rigid manipulators. In this case they give the best results to solve the simulation and control problems, as far as time consumption and programming simplicity are concerned. Here, the extension proposed is based on the theoretical notion of description formalism of a motion and on the use of the D'Alembert principle.
A generalized predictive controller for ship's steering is introduced. The parameters of the controller can be online adjusted based on some intelligent rules according to the heading error and the differential of...
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A generalized predictive controller for ship's steering is introduced. The parameters of the controller can be online adjusted based on some intelligent rules according to the heading error and the differential of the heading error. A recursive algorithm, which is based on the matrix disintegration, is used for matrix inversion; it needs as one third execution time as that of the general algorithm. Simulating results show that the intelligent controller can offset the effects of low frequency disturbances such as wind and current, follow the reference course and track quickly and accurately, and have good transient and steady state performances.
In this paper, we study the H ∞ control problem for singularly perturbed systems under imperfect state measurements by using the recursive approach. We construct a controller that guarantees a disturbance attenuation...
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In this paper, we study the H ∞ control problem for singularly perturbed systems under imperfect state measurements by using the recursive approach. We construct a controller that guarantees a disturbance attenuation level larger than a boundary value of the reduced-order slow and fast subsystems when the singular perturbation parameter ε approaches zero. In order to obtain the controller, we must solve the generalized algebraic Riccati equations. The main results in this paper is to propose a new recursive algorithm to solve the generalized algebraic Riccati equations and to find sufficient conditions for the convergence of the proposed algorithm.
This paper presents two recursive algorithms for parametric identification in the presence of both, noise and model uncertainties. The estimates provided by these algorithms are not invalidated by the observed input-o...
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This paper presents two recursive algorithms for parametric identification in the presence of both, noise and model uncertainties. The estimates provided by these algorithms are not invalidated by the observed input-output data and the assumed system and uncertainty structures.
recursive Least Squares (RLS) algorithms have wide-spread applications in many areas, such as real-time signal processing, control and communications. This paper shows that the unique solutions to linear-equality cons...
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recursive Least Squares (RLS) algorithms have wide-spread applications in many areas, such as real-time signal processing, control and communications. This paper shows that the unique solutions to linear-equality constrained and the unconstrained LS problems, respectively, always have exactly the same recursive form. Their only difference lies in the initial values. Based on this, a recursive algorithm for the linear-inequality constrained LS problem is developed. It is shown that these RLS solutions converge to the true parameter that satisfies the constraints as the data size increases. A simple and easily implementable initialization of the RLS algorithm is proposed. Its convergence to the exact LS solution and the true parameter is shown. The RLS algorithm, in a theoretically equivalent form by a simple modification, is shown to be robust in that the constraints are always guaranteed to be satisfied no matter how large the numerical errors are. Numerical examples are provided to demonstrate the validity of the above results.
Tire-road friction is the most important characteristic defining the planar dynamics of wheeled vehicles. It has consequences on the drivability, stability and tuning of the active vehicle dynamics control systems. Th...
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Tire-road friction is the most important characteristic defining the planar dynamics of wheeled vehicles. It has consequences on the drivability, stability and tuning of the active vehicle dynamics control systems. This paper proposes two online friction estimation methods designed for the adaptation of vehicle dynamics control algorithms. The problem is framed as a classification problem where inertial measurements are used to discriminate between high and low friction regimes. The first method merges a recursive least-squares (RLS) algorithm with a heuristic bistable logic to classify the friction condition and promptly react to its changes. The second method runs a classification algorithm on the slip-acceleration characteristic. Both methods simultaneously account for the longitudinal and lateral dynamics and are tested on experimental data.
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