Develop integration tests for pinch valve

[martukas]

What has to be done Figure out ways to test the following for the pinch valve:

• test that it's wired correctly and rotates in the correct direction
• test homing of pinch valve
• automatic linearization / calibration or confirmation of linearlization Tests should be fully automated and without human intervention. They should answer in the affirmative or negative - is the subsystem working correctly? Alternatively, as for the calibration, for example, it should record some values that can be compared for deviation from expected values.

How do you know it has to be done Right now we are making a lot of assumptions about correctness of the lower layers of software and electronics. We should be testing some of those layers on a regular basis, which should also help us establish troubleshooting and regression procedures for QA and validation later on. Some of these tests might be adaptable as self-tests in the final production units.

Code pointers We have some alternative pinch valve designs that can incorporate endstops and/or rotary encoder. We will soon have other sensors external to the prototype itself that can be use to help with replicating characterization and linearization tests. Ask @martukas about server credentials and connecting up a prototype for experimentation. Ask @sglow about homing and linearization, as he has experience with those features.

[martukas]

The Posifa flow sensor is hooked up to Pizza4 on the test server, which can act as reference sensor for calibration.

[inceptionev]

Lineariation table is implemented here: https://github.com/RespiraWorks/Ventilator/blob/master/software/controller/lib/core/pinch_valve.cpp

It is currently a fixed table of constants, but it should be replaced by this automated characterization.

[asmodai27]

This resembles the kind of tests we need for #307 and #759, except we might want to integrate an external sensor rather than rely fully on the vent's sensors.