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The first objective of this paper is to introduce a nonlinear system to model the heart rate (HR) response during and after treadmill walking exercise. The model is a feedback interconnected system that has components to describe the central and peripheral local responses to exercise and their interactions. The parameters of the model were experimentally identified from subjects walking on a treadmill at different speeds. The stability of the obtained nonlinear model was mathematically proven. The modeling results demonstrate that the proposed model can be useful in examining the cardiovascular response to exercise. Based on the nonlinear model, the second objective is to present a computer-controlled treadmill system for the regulation of HR during treadmill exercise. The proposed nonlinear controller consists of feed-forward and feedback components. The designed control system was experimentally verified and the results demonstrated that the proposed computer-controlled treadmill system regulated the HR of the experimental subjects according to two different exercising HR profiles, indicating that it can play an important role in the design of exercise protocols for individuals. Index Terms--Cardiovascular system, exercise, H-infinity control, linear-quadratic (LQ) control, modeling, nonlinear systems, parameter estimation.

This note addresses problems of detectability and output feedback stabilizability of nonlinear systems with globally Lipschitz nonlinearities via limited capacity digital communication channels. The main results are given in terms of Riccati algebraic inequalities. A simulation result on the control of a flexible joint robotic system is also presented. Index Terms--Control over networks, detectability, networked control systems, robust control, stabilizability. Digital Object Identifier 10.1109/TAC.2007.894542

We study a problem of K-barrier coverage by employing a network of self-deployed, autonomous mobile robotic sensors. A decentralized coordination algorithm is proposed for the robotic sensors to address the coverage problem. The algorithm is developed based on some simple rules that only rely on local information. By applying the algorithm to the robotic sensors, K layers of sensor barriers are formed to cover the region between two given points. To illustrate the proposed algorithm, numerical simulations are carried out for a number of scenarios. [ABSTRACT FROM PUBLISHER]

This paper addresses the problems of barrier coverage and sweep coverage in a corridor environment with a network of self-deployed mobile autonomous robotic sensors. Using the ideas of nearest neighbor rules and information consensus, we propose a decentralized control law for the robotic sensors to solve the coverage problems. Numerical simulations illustrate the effectiveness of the proposed algorithm. The results in this paper demonstrate that such simple motion coordination rules can play a significant role in addressing the issue of coverage in a mobile robotic sensor network. [ABSTRACT FROM AUTHOR]

The aim of this paper is to study the human Heart Rate (HR) response during walking, cycling and rowing exercises using linear time varying (LTV) models. We used the frequency of exercise locomotion as the input to the model. This frequency characterizes the stride rate, cadence rate and strokes rate of the walking, cycling and rowing exercises respectively. The time varying parameters in the LTV models were estimated by the Kalman Filter (KF). The results in this study demonstrate that HR responses to these exercises exhibit some degree of time varying nature.

In this study, a control design is proposed for the tracking control of heart rate response during treadmill exercise. The controller tracks an exerciser's heart rate to a given heart rate profile, that may represent a prescribed exercise protocol, by varying the speed of the treadmill. A guaranteed cost control approach is adopted in the control design so that the controller guarantees a certain level of performance. The effectiveness of the proposed control design is demonstrated via a simulation study. The controller will be useful in the design of exercise protocols for individuals.

Noninvasive portable sensors are becoming popular in biomedical engineering practice due to its ease of use. This paper investigates the estimation of human oxygen uptake (VO(2)) of treadmill exercises by using multiple portable sensors (wireless heart rate sensor and triaxial accelerometers). For this purpose, a multivariable Hammerstein model identification method is developed. Well designed PRBS type of exercises protocols are employed to decouple the identification of linear dynamics with that of nonlinearities of Hammerstein systems. The support vector machine regression is applied to model the static nonlinearities. Multivariable ARX modelling approach is used for the identification of dynamic part of the Hammerstein systems. It is observed the obtained nonlinear multivariable model can achieve better estimations compared with single input single output models. The established multivariable model has also the potential to facilitate dynamic estimation of energy expenditure for outdoor exercises, which is the next research step of this study.

A dynamic model of the heart rate response to treadmill walking exercise is presented. The model is a feedback interconnected system; the subsystem in the forward path represents the neural response to exercise, while the subsystem in the feedback path describes the peripheral local response. The parameters of the model were estimated from 5 healthy adult male subjects, each undertaking 3 sets of walking exercise at different speeds. Simulated responses from the model closely match the experimental data both in the exercise and the recovery phases. The model will be useful in explaining the cardiovascular response to exercise and in the design of exercise protocols for individuals.