More ways to prevent integral windup #34
Description
It'd be very beneficial to provide more ways to prevent integral windup, besides the limit of the integral term.
Among others, there are 2 very simple but effective methods: back-calculation (or tracking) and conditional integration (or clamping).
Both are similar in that they modify the integrator behaviour when the command output is saturating. See for example https://cse.lab.imtlucca.it/~bemporad/teaching/controllodigitale/pdf/Astrom-ACC89.pdf for a reference.
Conditional integration is particularly easy to implement : if the output is saturating (i.e. output is beyond output_limits), then we simply skip the integral term update.