Air Volume Control of a Medical Ventilator

Yih-Choung, Yu, Electrical and Computer Engineering
Author Profile
Initial Publication Date: October 12, 2023

Summary

This lab assignment was created during the COVID-19 pandemic, during which students were taking hands on lab remotely. The purpose for the assignment is to guide students to apply the PID motor angular position controller design to a real application in a medical ventilator, an important topic during the COVID time.

In the assignment, a set of a servo motor with optical encoder, a voltage amplifier, and a Q8 data acquisition board from Quanser was used on a bench for a team two students working together. Since the lab was delivered remotely, a VPN network was installed in each desktop in the lab with Matlab/Simulink with QUARC installed in the computer. Students can log in to their pre-assigned computer to work on this assignment. The instructor was in the lab during the lab session to monitor the motor on site and help students upon request.

This assignment (a small project) was designed for students to complete in two lab classes (2 hours and 50 minutes for each lab class). All groups finished the assignment successfully within the 2 weeks of lab time. No additional work outside the lab was needed.

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Learning Goals

(1) Students need to know how to perform PID controller design using pole-placement in Matlab and implement the controller with the dynamic model of the motor in Simulink.
(2) Since it is an application for medical device, safety issues and physiological constraints need to be addressed in the design.
(3) Each team is required to give a 10-minute presentation of their design to the class.

Context for Use

(1) This lab assignment is for a control systems lab, an undergraduate level course for senior students.
(2) It is for a class size of up to 6 groups (12 students) in each lab section.
(3) The assignment was delivered by a teaching faculty in a small institution without any TA in class.
(4) Prior to this assignment, students have programming experiences in Matlab/Simulink and are able to design PID controller for position control with the motor provided in the lab.
(5) The lab assignment provides description for students to calibrate the chamber volume of a ventilator to angular position of the given motor.
(6) It is a valuable exercise to show students how controller design can be applied to different applications in other disciplines, a medical device in this case.

Description and Teaching Materials

The idea of this assignment can be shared with instructors with interests. The hardware used in the assignment was the Servo 2 servo motor with sensors, the Q8 data acquisition system, and the voltage amplifier from QUANSER. The real-time control software was implemented with QUARC from QUANEAR. It can be used with other motor-amplifier unit with optical encoder by changing the software drivers in Simulink. For real-time controller implementation, it is possible to use data acquisition boars that are compatible with the Real-Time Windows Target.
Lab Assignment for students (Acrobat (PDF) 205kB Sep25 23)
PID controller design using pole-placement (Acrobat (PDF) 549kB Sep25 23)


Teaching Notes and Tips

The handouts provided for assignments include guidance for students to perform their own derivations step-by-step in PID controller design.

Assessment

All student teams completed their assignment within the given time. No additional work was needed outside the lab other that the pre-lab exercise.

References and Resources

This teaching activity was created as a part of the Teaching Computation with MATLAB Workshop held in 2023 at Carleton College.