I don't know much about erlang or elixir. Erlang was popular at work for a short period of time, but I think more people are fans of Haskell now (seems Scala may even be falling out of favor a bit).

As Seren said, C is pretty much defacto at the moment. C has a fairly large community. What would be gained by using Erlang? My understanding is that Erlang is geared toward distributed systems. I can absolutely imagine an massively distributed control system would benefit from Erlang. If you think of 'robotics' like cars where there is essentially a different robot for each control, maybe Erlang is a good fit. If the device is going to have a single CPU, maybe not so much.

It really depends on the application and the architecture, but to me, Erland isn't a natural choice.