4 ms·

So I do not have a medical background. I have however worked a number of Industrial Control Systems (ICS) projects, and what you describe kind of sounds like a

So I do not have a medical background. I have however worked a number of Industrial Control Systems (ICS) projects, and what you describe kind of sounds like a PID control loop, which also is not a simple push up/down approach. From Wikipedia:"A proportional–integral–derivative controller (PID controller or three-term controller) is a control loop mechanism employing feedback that is widely used in industrial control systems and a variety of other applications requiring continuously modulated control. A PID controller continuously calculates an error value e(t) as the difference between a desired setpoint (SP) and a measured process variable (PV) and applies a correction based on proportional, integral, and derivative terms (denoted P, I, and D respectively), hence the name." Getting PID control loops to work has a lot of research behind it, but it's still hard to get right with new hardware. I would imagine a PID control loop involving organics (wetware) would be much order, and harder still a PID control loop in organics with life-threatening failures possible.

jablongo 3y ago
At this point all the major solutions are using an algorithm that would probably fall under the umbrella of "Model Predictive Control" rather than a vanilla PID controller. An absurd spate of patent trolling occurred back in the early 2000s related to Controller definitions like these though. Researchers patented the use of a "PID controller in artificial pancreas systems" [1][2] which slowed down the development of APSs by many years. The way the Supreme Court recently changed patent law [3] for software has definitely had a positive effect for APS development. [1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2769814/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2769814/ [2] https://patents.google.com/patent/US20150306314 https://patents.google.com/patent/US20150306314 [3] https://en.wikipedia.org/wiki/Alice_Corp._v._CLS_Bank_International https://en.wikipedia.org/wiki/Alice_Corp._v._CLS_Bank_Intern...
- tremon 3y ago
  An absurd spate of patent trolling occurred back in the early 2000s related to Controller definitions like these That's good news, right? That means that everything that people now come up with has well-documented prior art?
idiotsecant 3y ago
PID works well for most industrial controls, but it's a blunt instrument. Its mainly valuable because it's simple and doesn't really require much knowledge of the plant to implement. No 'model' is really required, other than the vaguest knowledge of first order dynamics. Instead of model knowledge you just iteratively tune it until it works. If you need a really optimal control trajectory minimizing or maximizing for some parameter, you are willing to do the system identification necessary for it to work, and you don't much care whether an electrician can understand how it works model-based controls are much better. as /u/Communitivity mentioned so called 'model based control' (which is an umbrella of techniques) is a much more powerful tool.

jablongo 3y ago

At this point all the major solutions are using an algorithm that would probably fall under the umbrella of "Model Predictive Control" rather than a vanilla PID controller. An absurd spate of patent trolling occurred back in the early 2000s related to Controller definitions like these though. Researchers patented the use of a "PID controller in artificial pancreas systems" [1][2] which slowed down the development of APSs by many years. The way the Supreme Court recently changed patent law [3] for software has definitely had a positive effect for APS development. [1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2769814/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2769814/ [2] https://patents.google.com/patent/US20150306314 https://patents.google.com/patent/US20150306314 [3] https://en.wikipedia.org/wiki/Alice_Corp._v._CLS_Bank_International https://en.wikipedia.org/wiki/Alice_Corp._v._CLS_Bank_Intern...

tremon 3y ago
An absurd spate of patent trolling occurred back in the early 2000s related to Controller definitions like these That's good news, right? That means that everything that people now come up with has well-documented prior art?

idiotsecant 3y ago

PID works well for most industrial controls, but it's a blunt instrument. Its mainly valuable because it's simple and doesn't really require much knowledge of the plant to implement. No 'model' is really required, other than the vaguest knowledge of first order dynamics. Instead of model knowledge you just iteratively tune it until it works. If you need a really optimal control trajectory minimizing or maximizing for some parameter, you are willing to do the system identification necessary for it to work, and you don't much care whether an electrician can understand how it works model-based controls are much better. as /u/Communitivity mentioned so called 'model based control' (which is an umbrella of techniques) is a much more powerful tool.