Survey of software usage for control

baggepinnen · May 27, 2022, 12:52pm

In order to understand how people in the Julia community (and outside) make use of software for control-systems analysis and design, I’ve put together a little survey. Answers to this survey will help us improve upon and prioritize upcoming work in the Julia ecosystem for control.

The first part of the survey is completely anonymous, and the less anonymous second part is optional.

If you work with control systems, please share this survey with your friends and colleagues.

Thank you for your contributions!
Fredrik

ufechner7 · May 27, 2022, 8:01pm

Is there any package providing a discrete PID controller with a good anti-windup strategy?

baggepinnen · May 27, 2022, 8:38pm

ModelingToolkitStandardLibrary.jl has a nice implementation of a continuous-time PID controller with anti-windup

github.com

SciML/ModelingToolkitStandardLibrary.jl/blob/a2d79c919cdcdb01c6a733ada7d9ea5e1084b99b/src/Blocks/continuous.jl#L251


      
          # Parameters:
          - `k`: Gain
          - `T`: [s] Integrator time constant (T>0 required)
          - `Ta`: [s] Tracking time constant (Ta>0 required)
          - `x_start`: Initial value for the integrator
          
          
# Connectors:
          - `err_input`
          - `ctr_output`
          """
          function LimPI(;name, k=1, T, u_max=1, u_min=-u_max, Ta, x_start=0.0)
              Ta > 0 || throw(ArgumentError("Time constant `Ta` has to be strictly positive"))
              T > 0 || throw(ArgumentError("Time constant `T` has to be strictly positive"))
              u_max ≥ u_min || throw(ArgumentError("u_min must be smaller than u_max"))
              @named err_input = RealInput() # control error
              @named ctr_output = RealOutput() # control signal
              @named gainPI = Gain(k)
              @named addPI = Add()
              @named addTrack = Add()
              @named int = Integrator(k=1/T, x_start=x_start)
              @named limiter = Limiter(y_max=u_max, y_min=u_min)

A discrete-time implementation is not yet available there unfortunately. I find that conditional integration, possibly with sign check for non-minimum phase systems, is usually effective for discrete time systems. Having a solid implementation of such a controller would be nice to have in the ecosystem!