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Modeling and control in physiology 29

Fig. 26 Feedback, feed-forward and adaptive control strategies. (The figure has been
modified from Houk, J.C., 1988. Control strategies in physiological systems. FASEB J. 2(2),
97–107.)

Fig. 27 Feedback vs adaptive control strategies: muscle system. (The figure has been
modified from Devasahayam, S.R., 2019. Neuromuscular control: spinal reflex and
movement. In: Signals and Systems in Biomedical Engineering: Physiological Systems
Modeling and Signal Processing. Springer Singapore, Singapore, pp. 387–409.)

controller modifies the controller parameters system rather than causing
immediate changes in output. Fig. 27 describes the feedback and adaptive
controllers applied to the muscle system (Devasahayam, 2019).

3.4 Control therapy applications

Control therapy for physiological systems can maintain human functions and
thus human life. Several control techniques have been proposed. The most
familiar control approaches used for therapy strategies are optimal control,
feedback control, feed-forward control and adaptive control.