Recently various kinds of tasks such as the inspections on the curved wall of a vessel are performed by mobile robots. In those cases, the robot has to travel on curved surfaces along the prespecified path and has to know its current position for the successful accomplishment of the tasks. In this paper, we propose a dead-reckoning formula for a two-wheeled mobile robot moving on a curved plane, and illustrate the formula with examples for cylindrical surfaces. The performance of the proposed algorithm will be analyzed through a series of experiments by the magnet wheeled mobile robot developed in our laboratory.

An adaptive interference canceller with an adjustable center weight is proposed to improve the performance of the conventional fixed center-weight canceller for applications in data transmission systems such as normal binary phase shift keying (BPSK) and direct sequence spread spectrum BPSK modems. The performance of the new interference canceller is shown to be better than that of the conventional canceller by analysis.>

In this paper the performance and realization of adaptive digital filters (ADF's) for differentially coded signals have been studied. A general formula that realizes the LMS algorithm for differentially coded signals is first derived. We use this formula for realization of ADM and ADPCM ADF's. Then, applying these algorithms to channel equalization, we study the performances of the two filters for the cases of using a time-varying and a constant convergence factor. If we consider the dynamic range and the sensitivity to the variation of parameter values as the important performance factors, the ADPCM ADF with a time-varying convergence factor is preferred. However, when we consider the system complexity, the use of the ADM ADF with a time-varying convergence factor is desirable.

In this letter, we propose a frequency-weighted block LMS (FWBLMS) algorithm that is based on minimization of the frequency-weighted block mean-squared error. The FWBLMS algorithm has an important advantage over the time-domain LMS algorithm in that it can be designed with different frequency weighting on error signal depending on the relative significance of various frequency bands. Application of the FWBLMS algorithm in adaptive linear prediction of speech is discussed.

Maintaining access efficiency to a data base as updates and/or usage patterns change often requires restructuring the data base. While analytical methods are available for determining the optimal point to restructure, they assume the mean access cost is a smooth function of time or the number of accesses and can be measured exactly at any point in time. The access cost in practice often varies, at least in the short run, In a random manner. This implies a nonzero probability of deciding the optimal reorganization point has been reached when in fact it has not. Determination of the optimal reorganization point must take into account the random behavior of the access cost and the probability (and cost) of deciding too early or too late to perform the reorganization. A technique for choosing the optimal reorganization point subject to random variation in the access cost is developed and some examples are presented.