Abstract-The pole-sensitivity approach is employed to investigate the stability issue of the discrete-time control system, where a digital controller, implemented with finite word length (FWL), is used. A new stability related measure is derived, which is more accurate in estimating the closed-loop stability robustness of an FWL implemented controller than some existing measures for the pole-sensitivity analysis. This improved stability measure thus provides a better criterion to find the optimal realizations for a generic controller structure that includes output-feedback and observer-based controllers. A numerical example is used to verify the theoretical analysis and to illustrate the design procedure.Index Terms-Closed-loop stability, digital controller, finite word length, optimization.

Abstract-This paper investigates a recently derived lower bound stability measure for sampled-data controller structures subject to finitewordlength (FWL) constraints. The optimal realization of the digital PID controller with FWL considerations is formulated as a nonlinear optimization problem, and an efficient strategy based on adaptive simulated annealing (ASA) is adopted to solve this complex optimization problem. A numerical example of optimizing the finite-precision PID controller structure for a simulated steel rolling mill system is presented to illustrate the effectiveness of the proposed strategy.

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The performance of mobile telemedical communications links based on the IS-54 and GSM cellular telephone standards (the most widely used commercial systems in North America and Europe, respectively) was studied by computer simulations. A photoplethysmography signal was used to investigate the transmission of medical data over simulated mobile phone channels. Various conditions were simulated in the communications path between a mobile transmitter and receiver, from perfect to distorted conditions. The results showed successful transmission, with bit error rates of better than 10(-7) at the receiver for the IS-54 standard. The performance of the IS-54 standard was superior to that of GSM in terms of minimum path delay variations, especially in built-up (urban) areas.

This paper introduces a new lower bound stability measure with Finite-Word-Length (FWL) considerations that provides a larger measure than existing bounds and gives a better estimation of the stability robustness of sampled data system with FWL controller implementations. The optimal realization problem of the digital PID controller with FWL considerations is addressed. This parameterization problem is formulated as a nonlinear programming problem with a maximum of four independent variables. A strategy based on Rosenbrock's hill climbing algorithm to solve the optimal realization problem of digital PID realizations is developed, and the methodology is applied to a steel rolling mill to illustrate the effectiveness of the new measure.

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This paper presents an overview of the design of mobile telemedical systems using cellular telephone channels. A mobile telemedicine communication system was studied using both the GSM and the IS-54 standards, which are the most widely used commercial cellular telephone systems in Europe and North America, respectively. A simulation using a photoplethesmography signal showed successful transmission of data with bit error rates of less than 10(-7) at the receiver for the IS-54 standard and less than 10(-5) for the GSM standard, depending on the mobile channel conditions used.