LMSC I am also thinking if they implemented some sort of dynamically adjusting (self-correcting) solution internally to reach system to converge to the set points, given the PID parameters are common for all temps? Is that the Delta (Es)?
Otherwise, how could a set PID parameters facilitate 3 different set points?
I don’t know what those ‘Delta’ temperatures are; they appear to be the interval of temperature over which the controller acts as a PID rather than as an on/off switch; if I’m right, the defaults seem to indicate that the Nurri’s default behaviour is to act as a PID controller over the whole range of temperatures from zero to the target. The mechanism of a PID controller is relatively simple:
The desired/Target value of the control variable (temperature for ‘us’, but it could be anything else) is compared to the actual value. The actuator output (for us, current to the heating element) is a function of:
- A proportion of the difference between the two values (so called ‘error’)
- The integral of the error over a certain period of time
- The derivative of the error with respect to a certain interval of time
“mathematically”
I = kP (Tg - Tm) + kI ∫(Tg - Tm)dt + kD d(Tg - Tm)/dt
Where Tm is the measured temperature and Tg is the ‘goal’ temperature
My understanding of the control board in the Nurri is that it allows monitoring of three probes/setting of three independent temperature targets, but it uses the same proportionality constants (kP , kI , kD) for all of them. The Vostok/Evo board contains three separate PID controllers.
The PID parameters should not only ensure that the target temperature is reached, but that it is reached as quickly and as stably as possible. However, even using a single set of parameters should enable some level of temperature control - possibly a very good and stable one.