Apparently few of you realize that all the really large commercial roasting plants use computer control. You also may not realize that simplified computer control of modern artisan roasting machines is becoming quite common. These control systems are simple programmable touch panels and they have extremely limited computing horsepower hence they do not have the ability to create complex multisegment profiles. Since I was striving to produce the absolute ultimate control system, I needed rather complex calculus math operations occuring a hundred times per second. That is why I wrote the software myself and also why it requires a pentium class computer to keep up. If any simple programmable touchpanel controller existed that could handle my math then I certainly would have used it. I have just posted two new letters sent to me from CCR owners. One is from a commercial coffee industry owner and the second is from a homeroaster who has been on this list and often buys his beans from SM. Rather than including these letters here on this list, scroll down the page athttp://www.computercontrolledroaster.comand read them yourself. My intention is not to sell you anything; I just want you to understand the importance of accurate roast profiles and that this is not easy to accomplish. Believe me, I was really well practiced and talented with my variac knob but it can't come close to the results of the computer control. Jeffrey Pawlan |
I'm loving this, but I have a suggestion. Offer a mod that will work on a network. I'm dead serious. The reason's simple -- a lot of people have a computer in their home. That's a given. But not everyone has a spare machin= e to commit to roasting. For that reason, it would be nice if the roaster could be parked on an ethernet segment and communicate with the PC that way= . In case of communications failure, the "client" (roaster) would revert to a built-in default profile to finish its roast. The world has gone insane with networked devices (the theme for this phenomenon, if anyone remembers the radio program "Ruby: Adventures of a Galactic Gumshoe" from the 80s, is the amazingly prescient episode "I'll Give You Fire"), but this one would be practical. Alternatively, if you're already using serial communication it'd be darned simple to route that over CAT5 wiring, or even CAT3. Sure looks nice. Good show. On 3/31/06, Jeffrey Pawlan wrote: <Snip> m <Snip> m <Snip> |
Jeffrey, Your software and setup looks phenomenal...lots of control, and yet easy to use. The reviews show that all your work is reflected in the quality of th= e cup. Great job. Craig in Marin On 3/30/06, Jeffrey Pawlan wrote: <Snip> m <Snip> |
Quoting Jeffrey Pawlan : <Snip> I have a hard time with that. What is so complicated that a cheap microcontroller couldn't do it? Do you really need to do anything 100 times a second? A big roaster with big heating elements or gas burners, a big metal drum, and a big bean mass surely doesn't change much in 10 ms. The complex calculus is ... a PDE, right? But it doesn't have to be solved at that level. PID controllers "solve" differential equations. I guess I am just very curious. I don't mean to sound so negative. But I can understand that a computer interface would be much easier to code and handle storing/sharing profiles, easier to use, easier to upgrade or patch, etc. -Paul |
Well, better still will be the day when this stuff isn't all proprietary, but when someone offers code as open source. That's NOT a criticism of Jeffrey. I have no brief with profit or business. But it's also true that a lot of communally built code can be pretty good, and IMO there'd be a lot of advantages to having code for this kind of thin= g accessibly to the scrutiny of the growing specialty coffee roasting community. There was a great article on profiling in the last Roast mag., BTW. - Scott On 3/31/06, Paul Sack wrote: <Snip> -- Scott |
On 3/31/06, Scott Marquardt wrote: <Snip> is <Snip> Yeah, I agree wholeheatedly with this.. I've been thinking about what it would take to design a damn good roasting machine with computer control and open sourcing it. It just seems like it would be fun to do. As for the OP claim that a machine needs to be a Pentium to provide adequat= e control, I'm not sure I'm buying it. While something like that might be needed to model the roast chambers, once the model is solved, it basically becomes a bunch of coefficients which reduce to a few additions and multiplications.. But who knows, I might be oversimplifying. I'm just thinking of how simple it is to compute a typical digital PID control signal. -- Steven Hay hay.steve -AT- gmail.com A Little Fable by Franz Kafka "Alas," said the mouse, "the whole world is growing smaller every day. At the beginning it was so big that I was afraid, I kept running and running, and I was glad when I saw walls far away to the right and left, but these long walls have narrowed so quickly that I am in the last chamber already, and there in the corner stands the trap that I must run into." "You only need to change your direction," said the cat, and ate it up. |
Most embedded processors for this type application use much less than a Pentium. The 8051 familyis popular, hundreds of variants are available from a lot of manufacturers. They have memory & I/O (including D/A & D/A) on the chip. I happen to be looking at a new TI chip : 16 MHz 16 MHz, low power. On 4/1/06, Steve Hay wrote: <Snip> this <Snip> e <Snip> nd <Snip> st <Snip> , <Snip> , <Snip> -- "Life is just one damned thing after another." - Elbert Hubbard |
This is a multi-part message in MIME format. Today's PID's have up to 8 ramps and 8 soak points. Given we are talking about a 16 or so minute process, I wonder if one needs more control points over the "standard" profile than that. It would be interesting to know how many standard "adjustment points' there are in a typical roast from someone like Tom. I think most of the RK drum folks are working with four or five. Also, with the PID, it does all the math necessary to adjust for different weight of beans (I go from 100 to 250), different ambients, and the different densities. It's watching the heat of the mass, knows the heater capacity, and is constantly adjusting to keep the mass on the target ramp/soak. I also wonder how much response one gets from a mass of 250g or so given the amps and BTUs we are using. From: homeroast-admin [mailto:homeroast-admin] On Behalf Of Steve Hay Sent: Saturday, April 01, 2006 3:45 PM To: homeroast Subject: Re: +reply re computer controlled roasting On 3/31/06, Scott Marquardt wrote: Well, better still will be the day when this stuff isn't all proprietary, but when someone offers code as open source. That's NOT a criticism of Jeffrey. I have no brief with profit or business. But it's also true that a lot of communally built code can be pretty good, and IMO there'd be a lot of advantages to having code for this kind of thing accessibly to the scrutiny of the growing specialty coffee roasting community. There was a great article on profiling in the last Roast mag., BTW. Yeah, I agree wholeheatedly with this.. I've been thinking about what it would take to design a damn good roasting machine with computer control and open sourcing it. It just seems like it would be fun to do. As for the OP claim that a machine needs to be a Pentium to provide adequate control, I'm not sure I'm buying it. While something like that might be needed to model the roast chambers, once the model is solved, it basically becomes a bunch of coefficients which reduce to a few additions and multiplications.. But who knows, I might be oversimplifying. I'm just thinking of how simple it is to compute a typical digital PID control signal. -- Steven Hay hay.steve -AT- gmail.com A Little Fable by Franz Kafka "Alas," said the mouse, "the whole world is growing smaller every day. At the beginning it was so big that I was afraid, I kept running and running, and I was glad when I saw walls far away to the right and left, but these long walls have narrowed so quickly that I am in the last chamber already, and there in the corner stands the trap that I must run into." "You only need to change your direction," said the cat, and ate it up. |