This paper deals with a passive-decomposition based control of bilateral teleoperation between a single master robot and multiple cooperative slave robots with time varying delay. First, we decompose the dynamics of multiple slave robots into two decoupled dynamics by using the passive-decomposition: the shape-system describing dynamics of the cooperative works and the locked-system representing the overall behavior of the multiple slave robots. Second, we propose a PD control method for bilateral teleoperation to guarantee asymptotic stability of the system with time varying delay. Finally, experimental results show the effectiveness of the proposed teleoperation.
By matching roadway images in an encountered scene with bird's eye views, the scope of humans' perception is expanded to a satellite-roadway-vehicle network. Based on the geometric consistency of the satellite images with as-is local terrain, in this paper, a computational mechanism is introduced for generation and adaptation of a roadway model transferable through the network. First, the chromatic complexity of the roadway area is represented as a palette of saliency colors via fractal sampling of the scene image. Next, the palette is adapted to the associated area in the bird's eye view. Finally, the palette is transferred to the bird's eye view for anticipatively following the roadway pattern. Experimental results demonstrate that the transferable model can be applied to the extension of the roadway pattern prior to physical access.
Because evolutionary algorithms (EAs) generally require many repeated evaluations of objective functions, it often takes considerable time to solve optimization problems. Parallel computation is one means to shorten the required computation time. In earlier works, the authors proposed an EA suitable for coarse-grained parallel computers, a genetic local search with distance independent diversity control (GLSDC). Though GLSDC has been applied successfully to several practical problems, its parallel efficiency abruptly drops off as the number of CPUs for computation increases. To achieve a higher parallel efficiency, the authors now propose a new EA, an asynchronous GLSDC (AGLSDC), constructed by reworking the algorithm of GLSDC. This paper introduces the proposed method and reports verification of the method through numerical experiments on several benchmark problems and a practical problem.
Mapping from visual information to motor commands is an important issue in the study of voluntary arm movement. The joint kinematics of a human-like planar arm, which is generally described as a nonlinear function in a Cartesian coordinate system, can be approximately linearized in a head-centered polar coordinate system. This study shows that the mapping from the muscle lengths to the hand position in a head-centered polar coordinate system can also be approximately linearized. In addition, this study proposes a diagonalization of the kinematics that involves adjusting the moment arms of the muscles; in this diagonalization, the muscle lengths of two bi-articular muscles are proportional to the distance and direction from the head.
This paper proposes a new analytical method for stability and control performance of a robust model reference adaptive control system (MRACS). In the past studies, the following analytical policy has been adopted, that is, deriving tight and quantitative conditions for a stable robust MRACS is not important since those conditions depend on unknown factors such as the transfer characteristic of the controlled object. As a result, the most important things about stability and control performance disappear in algebraic calculations based on many inequalities. Naturally, it is not easy to answer the following questions. How is the stabilization of a robust MRACS achieved? What can we prepare for design of a robust MRACS which has a sufficient stability margin and a better control performance? The motivation of this paper is to answer these questions. For the purpose, this paper defines a desired system for the model reference control, and uses an analytical model parameterized with the desired controller parameters. Especially in a main loop analysis, a certain equivalent feedback system is derived, and the stability of a robust MRACS is explained with an expanded notion of the L2 stability. According to this method, it is possible to understand stabilization of a robust MRACS. Furthermore, some useful findings for design of a robust MRACS can be obtained from the results of analysis and a numerical simulation.
In this paper, a global optimal traffic assignment strategy, i.e., Q value-based Dynamic Programming with Boltzmann Distribution is applied to the Kitakyushu City traffic system. The main idea of the proposed traffic assignment strategy is to calculate the expected traveling time for each origin-destination pair and the probability of selecting the next section, then to generate a considerable number of route candidates for the drivers based on the calculated probability. In the simulation, how to select the temperature parameter and the number of the route candidates is discussed in detail. The comparison between the proposed method and the shortest path algorithms indicates that the proposed method could reduce the risk of the traffic congestion occurrence and save the traveling cost effectively. In addition, the computation time is given to reveal the feasibility of the proposed method in large scale networks.
A heat exchanger controlled by manipulating flow rates is widely used and there often exist unknown disturbance flows in the system. If we approximate the distributed parameter system to a lumped parameter system by means of Method of Weighted Residuals (MWR) and apply a controller to depress the disturbance influence, we must take the following three points into account: (a) the system has bilinear terms with respect to not only the input but also the unknown disturbance, (b) we cannot observe the state vector directly because the components are generalized Fourier coefficients so they are not physical quantities, and (c) we must rely on estimators to obtain the internal temperature accurately due to the heat exchanger structure. In this paper, we consider H∞ control problems for such a bilinear system and design a bilinear H∞ controller using a bilinear observer. As a bilinear observer, we use ”a bilinear disturbance isolation observer (DIO)” which is an extension of a previous work. The performance of this observer-based H∞ controller is evaluated with several simulations and experiments.
This note considers the design problem of Gain-Scheduled (GS) controllers for Linear Parameter-Varying (LPV) systems whose state-space matrices are supposed to be parametrically affine with some mild constraints. To be precise, we consider two types of GS controllers, GS H2 and GS H∞ controllers. The controllers to be designed are supposed to have parametrically affine state-space matrices. In sharp contrast to conventional GS controller design methods, the scheduling parameters are supposed to be inexactly measured. Using parameter-independent Lyapunov functions, in which some conservatism is admitted, we give sufficient conditions for designing GS H2 and GS H∞ output-feedback controllers which are robust against measurement errors of the measured scheduling parameters. The proposed methods are formulated in terms of parametrically affine Linear Matrix Inequalities (LMIs) with single line search parameters. The methods recover the design methods of conventional GS output-feedback controllers, in which scheduling parameters are supposed to be exactly measured, with an appropriate choice of the line search parameters. A simple numerical example is included to illustrate our results.
This paper discusses the exact linearization problem of two-input affine systems via the dynamic extension based on the relative degree structure. A necessary and sufficient condition for two-input systems to be exactly linearizable via 1-degree dynamic extension is derived, and the input transformations of two-input systems with dynamic extension are classified into two forms. Finally, a method to derive the input transformation such that the transformed system is exactly linearizable via the dynamic extension is proposed. The proposed method is applied to a mechanical system.
In advanced countries, the number of elderly recipients who take medicines every day has been increasing due to the aging of the population. Since they have many risks of inappropriate medication (e.g. overdose), we develop an intelligent medicine case named iMec in order to assist their caregivers in monitoring their medication conditions. The medicine case can recognize whether a recipient picks up medicines from its storage space to check the adequacy of dosage, and can estimate the present behavioral condition of the recipient to check the adequacy of dosing timing. Therefore, it can detect signs of inappropriate medication by comparing the results with the correct dosage and dosing timing. The present medication condition confirmed by the medicine case is stored on a server computer so that caregivers can monitor the information through web interfaces. Moreover, emergency e-mails are sent to the caregivers when the medicine case detects a sign of inappropriate medication. We use the Hough transformation and background subtraction methods for dosage confirmation, and devise a novel Fuzzy inference method based on association rules for dosing timing confirmation. As results of experiments and simulations, we confirm that the medicine case is able to detect 4 kinds of medicines in its storage space, and is able to select the present behavioral condition from 11 kinds of candidate behavioral conditions corresponding to common dosing timings.
We develop Web-based typing software in order to collect keystroke data on a LAN, and investigate several characteristics of keystroke dynamics in Japanese free text typing. We perform experiments on 112 subjects, representing three groups according to the number of letters they could type within five minutes. In this experiment, we extract the feature indices from the keystroke timing for each single letter and for two-letter combinations composed of consonant and vowel pairs in Japanese text. Based on an identification method using a weighted Euclidean distance, personal identification for the three groups is evaluated and its high performance is confirmed in proportion to the typing level of the group.