La Spaziale Mini Vivaldi and pressure profiling - Page 5

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blondica73

Postby blondica73 » Apr 01, 2019, 1:24 pm

A couple of additional software features would be great
1. Since the ito board can measure water flow (granted that water flow is not extremely accurate), could you add a feature to do flow profiling if the user would like to do flow profiling instead of pressure profiling? This would mimic the DE machines.
2. For the control parameters for preinfusion to be determined by the status "preinfusion" instead of the assumption that preinfusion is in the 0-2.5bar range?

pcrussell50

Postby pcrussell50 » Apr 01, 2019, 2:04 pm

Beewee wrote:I'm also curious to know how the controller can control pressure with the vibe pump. This is the first example of pressure profiling I've seen using a vibe pump.


Yes, full control of vibe pumps has been a bit of a unicorn. Breville does it. But their control system is patented. And limited. If you have a Breville Dual Boiler and are NOT using the needle valve for flow profiling, you can get "two stage", hi and low flow, (think Slayer), through the onboard pump control.

OP, Congratulations on this, BTW. I remember when we PMed about it. I haven't yet read this whole thread but I will.

-Peter
LMWDP #553

blondica73

Postby blondica73 » Apr 02, 2019, 11:26 am

pcrussell50 wrote:
OP, Congratulations on this, BTW. I remember when we PMed about it. I haven't yet read this whole thread but I will.

-Peter


Yeah, it is much better than I expected. I did have to have the interface board shipped to family back in the EU and brought to the US.

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Denis

Postby Denis » Apr 08, 2019, 11:06 am

After playing a few days with the module and the soft all I can say is it's worth the money and the time. It's really complex and has alot of tweaks, settings. You can do anything , any profile whatever you want. You can control the shot in any way from start to finish, even intervene manually while pulling the shot.

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blondica73

Postby blondica73 » Apr 15, 2019, 11:51 pm

I believe the software could be tuned so that after finishing the flood stage it should not try to turn the water off but look for the next stage. I say this because i see a large water flow drop after the flood stage and then it takes the pump some time to catch up to the pre infusion profile.
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sandc

Postby sandc » Apr 17, 2019, 4:52 pm

> the software could be tuned so that after finishing the flood stage it should not try to turn the water off but look for the next stage. I say this because i see a large water flow drop after the flood stage

You should see that drop. Then it's working as intended.

In leva!'s terminology, flooding is the pressure-less stage before profiling can kick in. Its only purpose is to fill tubes and other air pockets with water, not brewing or preinfusion. The flow rate - of clear water, not espresso - in that stage is of no importance.

There can be no pressure profiling while there is easily compressible air in the fluid system. A vibe pump achieves little to nothing for a few seconds, pressure-wise, due to that air. The system must be filled almost entirely with water for pressure profiling to become possible. That's why the pump is run with full power until some pressure (0.7bar) appears.

At that point, pressure profiling becomes possible and the control loop kicks in. If you have a profile that begins at 0.7bar (or below, see "setpoint stitching" in manual), then the error in that moment is zero - because the pressure is where the control loop wants to have it. If the error is zero, the proportional output is 0. The integral output is 0, too, at 0s. Only the bias remains. As a logical result, the flow rate drops instantly and dramatically. If you see that drop, the control loop works as it must.

If you don't like the audible stutter generated by the transition from flooding to pressure control, start your profile at a higher pressure than 0.7bar (e.g. 1.2bar). In that case, the control loop can not let the output drop as much. You might want to try a different flood pressure setting, too.