A combination of two drugs (hydrochlorothiazide and

Chapter 18, Problem 18.21

(choose chapter or problem)

A combination of two drugs (hydrochlorothiazide and oxybutynin) is commonly used to regulate blood pressure in elderly patients. These two drugs mainly affect two physiological variables of the patient (blood pressure and urine production rate). Since the goal is to regulate both variables with these two drugs, interaction analysis has to be performed to design two SISO control loops. For the following model, there are two inputs and two outputs (Ogunnaike and Ray, 1994, p. 771.): where 0.0005, _.,, ~ J y1 =normalized (dimensionless) blood pressure Y2 = normalized urine production rate u1 = rate of hydrochlorothiazide ingestion u2 = rate of oxybutynin ingestion (a) Calculate the relative gain array. (b) What loop pairing would you suggest?