The paper presents a method for quantifying modelling error of an FIR model whose parameters are estimated by using the least squares method. This method is also applicable to a model whose transfer function is expressed by a linear polynomial of the parameters. First, we introduce the method proposed by G.C. Goodwin et al. The method assumes that the unmodelled dynamics of the system is expressed by realizations of random variables which have independent distributions with exponentially decaying variance. But the formulation of the modelling error is modified in this paper as Goodwin's formulation is rather difficult to understand. Second, we point out that Goodwin's approximation is of a rough and unpractical nature, and also that the modelling error obtained by the method is not frequency-dependent. Hence, we propose a revised method where an assumption in Goodwin's method is modified to a more reasonable one. We also propose a parameter estimation algorithm which needs much less computation time with little loss of accuracy of estimation. Finally, we show, through several numerical simulations, that the mean-squared error estimated by the revised method is much closer to the real modelling error than that obtained by Goodwin's method.
This paper presents a new method of visual servoing with stereo vision to control the position of a manipulator with respect to an object. Conventional control methods by visual servoing use a monocular camera and have several problems. For example, either shape information or desired distance of the target object from the camera must be given. Furthermore, it is not stable if the initial positional error of features in the image is very large. These problems are caused by image the Jacobian matrix, that is, the approximate value at desired position is used instead of correct one. By using stereo vision, the image Jacobian matrix can be calculated correctly at any position. So neither shape information nor desired distance of the target object is required. It is also stable even if the initial error is very large. Both simulation and experimental results are presented to demonstrate the effectiveness of this method.
This paper gives a concise parametrization of all generalized interactors of a discrete-time multivariable system. This is done by using state-space description of a given particular interactor. The paper then proposes a selection of the parameter which leads to an all-pass closed-loop transfer matrix. This closed-loop system turns out to be equivalent to an LQ optimal feedback system. A numerical example is given to illustrate the results.
Recently, mechanical CAD systems with solid model are used widely in the design process. However, it is not easy to build solid model with some kind of primitive objects and set operations. To solve this problem, we propose an algorithm of automatic conversion from wire-frame data to solid model. Although a large number of studies have been made on this area, previous methods couldn't handle solid objects with free-form surfaces and only treated polyhedra-approximated solid objects. Moreover, some of these approaches require lots of execution time. Because they are based on the combinatorial search algorithm which find actual faces of objects. Our approach solved above two problems on some conditions. It offers high-speed execution and can treat free-form surfaces.
Analysis of relation between flow speed and jam condition of automobile traffic flow on an expressway is neccesary to achieve appropriate traffic flow. A jam condition on an expressway is caused at the bottleneck points like the entrance of tunnels and others. So it is very important to grasp the flow condition at the bottleneck for analysis and estimation of automobile traffic flow. As the change of flow density is explained by flow demand and flow capacity at the bottleneck point, the estimation method of density field at upstream part and down stream part of the bottleneck point is reported on this paper using the characteristic lines method. And this paper reports that this method is also useful to analyze the density behavior by increasing and decreasing of vehicle number at the merging points and the diverging points of an interchange on an expressway.