IMPEDANCE MONITORING SYSTEM

摘要

Impedance to fluid flow in a fluid delivery line is measured. Two techniques are used depending on the flow rate selected. For high flow rates, the pump (18) is controlled to vary the flow rate and the change in pressure is divided by the change in flow to directly determine the resistance. For low flow rates, a processor (14) controls the pump (18) to pump flow quantities in accordance with a pseudo-random binary code. The resulting pressure signal sensed at the conduit (22) is decoded in accordance with that code. Pressures received during code periods of no flow are subtracted from pressures received during code periods of flow. Pressure offset is also removed and a least squares estimation approach is used with a linear prediction model to determine impedance. The coefficients determined in the model are used to calculate the resistance to fluid flow of the system. A quality supervisor monitors the resistance determination process and controls the display (28) of resistance depending on the quality determined. A resistance display (28) continuously displays the resistance of the system.