Abstract: Most peristaltic blood pumps in hemodialysis machines currently use open-loop control, which leads to a relatively high perturbation level of flow rate. For some reasons, the blood flow rate from the peristaltic pump canít be measured directly. In this research, two simple but effective methods including empirical formula and polynomial curve fitting are applied to describe the relationship between the blood flow rate and RPM of the pump head. Both of the two methods perform well in describing the relationship. But the modified empirical formula is preferred because of its relatively low computational complexity. Taking RPM of the pump head as an indirect feedback of the flow rate, a robust repetitive control method is applied to lower the fluctuation level of the blood flow rate. And the result exhibits a better performance when it is compared with the general repetitive control.

Keywords: Peristaltic pump, hemodialysis machine, blood flow rate, robust repetitive control.