A Localization Algorithm for Autonomous Mobile Robots via a Fuzzy Tuned Extended Kalman Filter

The capability to acquire the position and orientation of an autonomous mobile robot is an important element for achieving specific tasks requiring autonomous exploration of the workplace. In this paper, we present a localization method that is based on a fuzzy tuned extended Kalman filter (FT-EKF) without a priori knowledge of the state noise model. The proposed algorithm is employed in a mobile robot equipped with 16 Polaroid sonar sensors and tested in a structured indoor environment. The state noise model is estimated and adapted by a fuzzy rule-based scheme. The proposed algorithm is compared with other EKF localization methods through simulations and experiments. The simulation and experimental studies demonstrate the improved performance of the proposed FT-EKF localization method over those using the conventional EKF algorithm.     

An Integrated Voice Data Protocol for Slotted CDMA Personal Communication Networks

In this paper we propose a new protocol forintegrated voice/data traffic in personal communicationnetworks (PCNs) employing slotted packet code divisionmultiple access (CDMA). The concept of dynamic boundary is adopted in both code and timedomains to meet the different requirements for data andvoice traffic. This paper outlines and compares theperformance of three channel assignment policies. The network performance is measured in terms of theaverage voice blocking probability and average datadelay. A discrete-event simulation and a two-dimensionalMarkov model are developed for both the fixed boundary scheme and dynamic boundary scheme.The results indicate that an improved performance can beachieved by introducing the dynamic boundary scheme, andthe dynamic assignment policy results in a performance close to the optimal value. It isalso easier to be implemented.     

Visual Control of Robots with Delayed Images

This research develops a control scheme for visual servoing that explicitly takes into account the delay introduced by image acquisition and processing. For this purpose, a predictor block, i.e., an estimator that predicts several samples ahead of time, is properly included in the scheme. The proposed approach is analytically analyzed in terms of dynamics and steady-state errors, and compared to previous approaches. Furthermore, several simulations are comparatively shown in order to illustrate the benefits and limitations of the proposed control scheme. Finally, some experimental results using a turntable and a 3-d.o.f. Cartesian robot are provided in order to validate the analytical and simulation results.     

APPLICATION OF WEIGHTED NON- OSCILLATORY AND NON-FREE- PARAMETER DISSIPATION DIFFERENCE SCHEME IN CALCULATING THE FLOW OF VIBRATING FLAT CASCADE

A dual-time method is introduced to calculate the unsteady flow in a certain vibrating flat cascade. An implicit lower-upper symmetric-gauss-seidel scheme(LU-SGS) is applied for time stepping in pseudo time domains, and the convection items are discretized with the spatial three-order weighted non-oscillatory and non-free-parameter dissipation difference (WNND) scheme. The turbulence model adopts q-( low-Reynolds-number model. The frequency spectrums of lift coefficients and the unsteady pressure-difference coefficients at different spanwise heights as well as the entropy contours at blade tips on different vibrating instants, are obtained. By the analysis of frequency spectrums of lift coefficients at three spanwise heights, it is considered that there exist obvious non-linear perturbations in the flow induced by the vibrating, and the perturbation frequencies are higher than the basic frequency. The entropy contours at blade tips at different times display an intensively unsteady attribute of the flow under large amplitudes.     

Some Features of the Silver-Dye Bleach Process

Some important features of the chemistry of processing silver-dye bleach materials are outlined. The improvements in lightfastness, colour quality and sharpness, compared with colour development systems, are described.