Industry Research

[nebhead]

Currently watching this great video on YouTube from Mad Scientist BBQ which gets into the weeds on Pellet Grill Controllers. I found it really interesting to watch: https://youtu.be/CmCibXcfmqY

One idea I've gleaned from this is to look at adding a new fan (DC - computer fan with PWM?) to add some more options for modulating temperature.

Enjoy!

[faisalhusain007]

Hey Ben, been a long time since I checked in. I am finally back in sunny KL, been away for almost a year, just catching up with all the latest developments. Kudos to you and all the community here with the development of this project. I watched the Vid, I do actually own the 12v GMG but haven't used it since upgrading to my frankenstein traeger bbq75 thanks to you and PiFire.

I am also interested in going the variable speed on both the Auger and Fan, do you remember really early on when we were experimenting with the SSR we managed to use PWM to change the speed of the fan our goal was to get a better smoke flavour, but we decided to pause the fan at timed intervals as an easier solution. I think I posted it here #15 (comment).

Anyways I have finally tidied up my install and my grill looks kind of normal now.

WhatsApp.Video.2021-12-30.at.13.43.06.mp4

[nebhead]

Hey Ben, been a long time since I checked in. I am finally back in sunny KL, been away for almost a year, just catching up with all the latest developments.

Welcome back @faisalhusain007!! Awesome to see your setup, and it looks great! I like the clean box look.

I am also interested in going the variable speed on both the Auger and Fan, do you remember really early on when we were experimenting with the SSR we managed to use PWM to change the speed of the fan our goal was to get a better smoke flavour, but we decided to pause the fan at timed intervals as an easier solution. I think I posted it here #15 (comment).

Yep, definitely remember that early on. I think we can revisit this now, as it seems like it might be a good area to start optimizing even further. @weberbox just committed some changes to the PID which I think make it even better than it was before, but there is always room for more improvement. For some of us that have the SSRs, I think we can look into the PWM switching for fans, but for anyone with mechanical relays, they would be out of luck - unless they had a DC fan they could hook up. I think it's worth looking into that option too. I also really like the idea of being able to run the whole thing from 12V DC. A future board revision might be in order. :)

Interesting to hear in the video how other companies are achieving their set temperatures, and in some cases obscuring the true temperature swings. I know most of us would rather see the actual temperatures, I think it's interesting to have an 'easy' mode that does more averaging, or shows the user the rough set temperature.

Anyway, good to have you back, looking forward to what 2022 will bring for this project!

[weberbox]

I was looking up what fan Treager was using as I was thinking a pc fan might not have enough cfm.

The Treager fan is like $90 which is insane so I researched the specs and found the info below

Specs

Seems to be a 120mm fan with 128cfm

I found a few alternatives on Mouser and this one looks pretty good and much cheaper at $19

Mouser Fan

[nebhead]

Holy moly! That thing is going to helicopter out of there! :)

[faisalhusain007]

Ha! We will anchor to grill use it to move the grill around, add that module to the PiFire, industry first!
I got it doing the traeger smoke mode thing where it ramps up and down

Fan.ramp.mp4

I have the 12V supply connected to a step down buck powering pi and the fan. The 12v power supply outputs 12V@2A seems plenty enough for both the Fan and pi . No other extra components are being used , just using the 3.3V pwm output from the pi to control the fan. I want to add the pwm stuff to the pid control what do you guys think?

[nebhead]

I have the 12V supply connected to a step down buck powering pi and the fan. The 12v power supply outputs 12V@2A seems plenty enough for both the Fan and pi . No other extra components are being used , just using the 3.3V pwm output from the pi to control the fan. I want to add the pwm stuff to the pid control what do you guys think?

Yeah, maybe create a new grillplat_pifire_dcfan.py module to play with, and see where it takes you.

[faisalhusain007]

Sure, which pins to use for PWM and do we want to detect the output from the Fan tacho(RPM), if so which pin ?

I will start adding functions we want PWM linked to the PID control and for the smoke modes we can use the existing stop and start and do want to add a ramping mode like the traegers have ?

[nebhead]

TBH, I hadn't thought through the details. :P I'd say, use any of the pins on the aux header that aren't being used for buttons right now.

(16, 20, 21 are used) Might check @weberbox's board too to make sure there aren't any conflicts with assigned GPIOs. Other than that, go crazy! :)

Thinking this through a bit, you may want to start a new pid.py as well, that we can utilize for systems with the DC fan control. So basically you'll want to create two new files and for now you'll need to edit control.py to load those files instead of the defaults. For the grill_platform you may want to look at switching to GPIOZero to control the GPIOs, and furthermore controlling the PWM output in a simpler fashion. https://gpiozero.readthedocs.io/en/stable/api_output.html#pwmoutputdevice

Using the above would be easy enough to implement the stop/start, as it could potentially ramp up/down when you just turn it on/off using the current smoke+ mode.

[faisalhusain007]

Thanks, I have made some progress got the fan working for both normal /hold modes. For smoke+ I just use range of duty cycles that ramps up the range (0.1 seconds) then ramps down again. I made some minor changes to common to add a couple io pins one for the pwm and one tacho. Pointed control to my grillplat, works ok so far using GPIO. Where I am stuck is with the PID control, not to sure how to integrate the fan with the auger .

Any clues?

[nebhead]

Where I am stuck is with the PID control, not to sure how to integrate the fan with the auger .

You know, that's an excellent question. It'd be something we will have to play with. At first blush, I would think that having two separate PID's would be necessary. But I could be completely wrong on this. It just seems to me, that there would be different inputs and outputs needed for that - but I'm definitely not any kind of expert on PID. The fan adjustments can be made more often, I would think, than the auger adjustments. So this might mean an additional modification to the control script, to add a separate fan PID, (could use the same PID module), that gets evaluated more often. Maybe every 5-10 seconds. Yeah, I think this is going to take a little deeper thought and research.

[faisalhusain007]

yeah that's where I am stuck, trying to get to grips with it in my head, if we have 2 pids would they conflict with each other,although its way easier to have 2 pids I already have the something ready that I can implement, but in real terms would that make the end cook better? I want something that's as easy as set it and forget about it, but the taste of pitmaster working the grill dedicating hours of their life for that perfect smoke imparted protein flavour. Going back to the original video you posted at the top of this thread it seems we need that 'variance' to create that true bbq flavour, not a perfect deadline in terms of temperature. A few years back I built a Dry Ager (Drinks fridge, fans, UV lights, Ozone generator, dehumidifier and humidity generator all running of a ESP12 module) I found I needed to add as much as 30% variance to the set parameters to achieve amazing results.

[thomasstrach]

I used to work with PIDs on the industrial field a lot.Using 2 controllers in a row or as follow up controller is possible but sounds a bit too much in this case. It’s usually used to control a huge amount of heat that will have a very slow impact on the outcome (pool heating) to avoid a huge overshooting. Means it’s not the right control method here for heating air. When I installed the PiFire on my pellet smoker it was easily running the 500F quite precise but it was struggling with 180F. So I need to find the correct speed of the fan in combination with the PID settings. Too much air will blow out the fire, too many pellets will cause too much heat. In the end I slowed down the fan speed manually to reach the correct ratio of air and settings in PID mode. It took me about 3 days and 10 pounds of pellets. It would be helpful for me to set different fan speeds for different temperatures or in relation to the temperature. This will make an easy and smooth low temperature accuracy with nice amount of smoke and will also make it easy to reach high temperature for constant fire to grill flamed salmon or make pizza on a stone plate above the fire at 900 F. This will need some further adapted settings… In combination with the other findings for the smoke mode it sounds very interesting to work with a controlled fan. Might have other positive impacts as well, like a faster start when the fan starts running slow in the beginning and most likely less pellet consumption at all.

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Am 14.01.2022 um 05:00 schrieb faisalhusain007 ***@***.***>:  yeah that's where I am stuck, trying to get to grips with it in my head, if we have 2 pids would they conflict with each other,although its way easier to have 2 pids I already have the something ready that I can implement, but in real terms would that make the end cook better? I want something that's as easy as set it and forget about it, but the taste of pitmaster working the grill dedicating hours of their life for that perfect smoke imparted protein flavour. Going back to the original video you posted at the top of this thread it seems we need that 'variance' to create that true bbq flavour, not a perfect deadline in terms of temperature. A few years back I built a Dry Ager (Drinks fridge, fans, UV lights, Ozone generator, dehumidifier and humidity generator all running of a ESP12 module) I found I needed to add as much as 30% variance to the set parameters to achieve amazing results. — Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you are subscribed to this thread.

[faisalhusain007]

Hey @thomasstrach thanks for the info. I have been playing with the pid and fan control and see your point. I too think that it maybe better to have different speeds for different temps as a set point rather than using pid control in this instance. Could you please share your findings in your 3 day experiment. @nebhead perhaps we could add to the webgui a section for fan speed startup and smoke mode ramp range and high temp grill speed to max or something like that. The speed is based on the duty cycle and frequency. I found success with frequency over 1KHz.

Here is the fan ramp function (Smoke+) in grillplat

def FanRamp(self):
        self.pi_pwm.start(0)
        for duty in range(0,50,1):
            self.pi_pwm.ChangeDutyCycle(duty) 
            sleep(0.1)
            sleep(0.05)
    
        for duty in range(50,-1,-1):
            self.pi_pwm.ChangeDutyCycle(duty)
            sleep(0.1)
            sleep(0.05)

I only use 50% duty cycle because the fan is on my test bench and not secured anymore it will try and take off!

[nebhead]

I think you guys are on the right track here. I'm thinking it might make sense to build a 'spreadsheet' of values such that we have fan speed targets for different temperature ranges that work well. We could even have these be configurable in the settings webui. This way we can tweak them as needed? Or maybe it should just be a set of fixed values?

[faisalhusain007]

Maybe both on the development branch and fixed for the main production, could be not every grill is the same or pellets used etc

…

On Sat, 15 Jan 2022, 09:50 nebhead, ***@***.***> wrote: I think you guys are on the right track here. I'm thinking it might make sense to build a 'spreadsheet' of values such that we have fan speed targets for different temperature ranges that work well. We could even have these be configurable in the settings webui. This way we can tweak them as needed? Or maybe it should just be a set of fixed values? — Reply to this email directly, view it on GitHub <#60 (reply in thread)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AIZKCHH4OMI3SHKH2XDE7JLUWDHE3ANCNFSM5K62EVKQ> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>. You are receiving this because you were mentioned.Message ID: ***@***.***>

[nebhead]

I think for now, everything on the development branch until we can gain some confidence. Then once it's all looking good, push to main.

[nebhead]

One other thing, I think would be really cool, is to build-in pellet burn rate. Or more simply, auger-on time vs. total runtime. That could be a nice metric to add to the pelletdb, so that we could track what brands of pellets are burning faster, etc. Just an idea.

[faisalhusain007]

One other thing, I think would be really cool, is to build-in pellet burn rate. Or more simply, auger-on time vs. total runtime. That could be a nice metric to add to the pelletdb, so that we could track what brands of pellets are burning faster, etc. Just an idea.

Yeah for sure

I think for now, everything on the development branch until we can gain some confidence. Then once it's all looking good, push to main.

yep agree

[faisalhusain007]

@thomasstrach Please can you share your fan speeds for different temps would be interested to see how we can implement it. Thanks

[faisalhusain007]

Thing is in KL everyday is almost the same, for this test same batch of pellets were used as I usually use. Lid was kept closed throughout. It dawned on me, the only thing I have done differently for testing is I cleaned the whole grill before fitting the dc fan I didn't bother to install the drip tray, I thought it's not going to make a difference as long as the baffle is there on top of the firepot should be ok.

Do you think that would make a big difference? I am guessing not.

[nebhead]

Hmm... it might. It's a pretty big baffle itself and might be something that tempers the heat fluctuations. It's possibly worth trying in the same config.

[faisalhusain007]

Yep It made a huge difference, here is the same config and setup with the drip tray installed check out the graph now

[nebhead]

Oh much better. How many degrees of swing is it on average?

[faisalhusain007]

Around 3 to 5