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makers-for-life / makair-firmware

🧠 [Software] Firmware for the MakAir microcontroller. The brain of the ventilator.
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Add Support for Stepper Motors and Second Mass Air Flow Sensor. #3

Closed bruprescott closed 4 years ago

bruprescott commented 4 years ago

Hello,

Would it be possible to add support for stepper motors in the code? The faulhaber motors are difficult to find here in Brazil.

It could add support for a second mass air flow sensor to monitor the exhalation flow and contribute to the future implementation of assisted modes.

pi-r-p commented 4 years ago

Hello,

We did one prototype machine with steppers, but it is not inside the same code. My goal is to develop a stepper control board to be compatible with Faulhaber (pwm command).

For the proof of concept, we used one nucleo board + one nucleo ihm05a1 expansion board. The expansion board manages half steps only, and you need to raise current dynamically when you start moving. Holding the position require less current. If you always keep max current, self heating is too high.

Results are:

We will keep on this development, but it needs again a new electronic board + valves adaptation.

Test code is here, feel free to take it. Acceleration ramps are really important with such high torque, and the optical switch is placed in the middle of the course, to be sure to always realign zero position one time per cycle.

I choose motors to be able to deliver 0.22N.m @1000 pulse/s... There is a few. Mechanic is really prototype... IMG_1122

pi-r-p commented 4 years ago

For your second question : mass air flow (or differential sensors) is really a complicated matter as long as you need to plan to buy 5000 units. We are still struggling with it.

bruprescott commented 4 years ago

Hi @pi,

Thanks for the feedback, it has helped me a lot. Just so you understand, I've been doing all the tests on a ship. I've been here for many days already, my forecast is to go home in two weeks. So I want to have the whole project ready for purchase. Luckily for me, I have many arduinos, stm, rasp, motors, encoders, DP sensors available to perform the tests. We have complete onboard lathes.

I will implement the controls on an external board to perform tests.

About noise: Did you try to use a sealed box around the set? I already did something similar for another project and it worked.

About the purchase, I am calling several partners. Our idea is to assemble 1000 units, as soon as we get the approvals from the regulators here in Brazil (ANVISA). For approval, assisted mode is required. So I have run out of time. We have deaths around 650 + / day.

Could you share details of the used bldc outrunner? KVM, RPM? Could you show a photo of the engagement? my e-mail: bruno@prescott.com.br / bruno.prescott@bmptech.com.br

Thank you!

jabby commented 4 years ago

ping @pi-r-p

jabby commented 4 years ago

After verification with @pi-r-p this issue can be closed.