Critical reviews in biomedical engineering
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Closed-loop (feedback) control of skeletal muscle is critically reviewed. The introductory section examines the advantages and disadvantages of open-loop as compared to closed-loop control in general, defines the problem, and outlines our approach. In the biological systems section, muscle structure and function are defined at the level of the motor nerve, neuromuscular junction, and sarcomere. ⋯ The focus of this section is the paralyzed individual: past progress and future directions. An extensive bibliography of cited references is then provided so that the interested reader may pursue his/her particular area of interest in more detail. The authors acknowledge that such an extensive review of so many relevant areas is necessarily not complete and often overly simplistic, but our goal is a "first approach" to a comprehensive understanding of the closed-loop (feedback) control problem for achieving movement in paralyzed skeletal muscle.
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Crit Rev Biomed Eng · Jan 1982
ReviewAutomated control of physiological variables and clinical therapy.
Improved transducers and low-cost computational power make the development of on-line systems to control physiological variables and clinical therapy feasible. This review deals only with systems that provide control by the infusion of chemical agents or by changing the concentration of respiratory gases; control provided by electrical stimulation or mechanical means (orthotic and prosthetic devices) are not considered. ⋯ There is a general need for the development of new sensors for physiological variables, algorithms for adaptive control, and controllable miniature activators for delivering therapeutic agents. Proposed control systems should be thoroughly evaluated in a realistic environment, preferably by comparing them with systems that they were designed to replace.
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This article reviews the history of attempts to define in quantitative terms the relationship between a processed electromyographic signal and the corresponding force produced by skeletal muscle. Numerous reports have indicated a linear relationship between isometric force and rectified, integrated EMG. These reports, the nature of their experiments, and the disagreements among them are reviewed. ⋯ The effect of joint position and level of muscular effort in the isometric case are discussed. Various proposed mathematical models of the force-EMG relationship are presented and analyzed. The concluding section of the paper summarizes the current areas of agreement and disagreement and comments on the feasibility of obtaining force-EMG relation in the presence of movement.