[time-nuts] Neural net to control oven temperature ?

[Achim Gratz]

Glen English VK1XX writes:
> Has anyone tried to use a Neural net to control oven tmep, rather than
> the ye olde PID ?

If you believe the marketing, that is why the Nest thermostat is
connected to the cloud.

> IE the algorithm learns from previous beheviour and successfully
> predicts behaviour (or not).

This part is (unsupervised) learning, not control.  Depending on how
much knowledge you bake into the neural network about the system, you
either need to learn just the system parameters (say the PID constants)
of a fixed system or figure out the system structure itself, the latter
part is called system identification.  Unless you expect the system to
change over time it is usually (much) more practical to stop the
learning at some point and just run the system with the best model
available so far.  Incidentally that is one reason why different
hardware for neural network acceleration exists: the network for
learning is usually much more complex and needs higher precision than
the network running the extracted model.  If you need to keep learning
after the initial training (and if it has to be online learning rather
than periodic offline re-training), the learning rate often has to be
reduced significantly in order for the control to stay inside reasonable
bounds.

> I'm sure there are a few out there proficient with machine learning
> algorithms.

Neural networks are best applied to sparse, low-dimensional signals
embedded in high-dimensional spaces.  Oven temperature control doesn't
fit that description, so more traditional methods are likely more
efficient.

> Might make a good masters thesis I bet.

Maybe so, but there are probably sexier topics around for a
master-to-be to pick up.

> Given that oven control based on inputs and whatever is not random,
> unlike say flicker etc.

Randomness actually helps in many learning tasks.


Regards,
Achim.
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