Hi everyone,

I’m working on a project where I need to control a mechanism in SimWise 4D (Image 1) using a Simulink co-simulation.

The goal is to control the needle speed along the Z-axis by adjusting the motor velocity (marked in Image 1). Currently, when the motor runs at a constant 90 deg/s, I get the needle speed shown in red on the graph (Image 2). However, I want the needle to follow the profile sketched in green, which is basically the same motion but capped/saturated at 200 mm/s.

Image 3 shows my Simulink setup. The SWplant block takes motor velocity as an input and outputs the needle speed. I exported the original data from SimWise, imported it into MATLAB, and used a Saturation block to create the reference signal I'm trying to hit.

The problem is that I can't get the PID controller to behave. I tried using the PID Tuner and even attempted manual tuning, but the system gives really weird, unstable responses and doesn't follow the green curve at all.

I've made sure all units are in degrees (no radians mixed in), and the mechanism works fine on its own with a constant input, but the feedback loop just breaks it.

Has anyone dealt with SimWise/Simulink co-simulations before? Any idea if I'm missing something with the S-function block or if there's a specific way to handle the nonlinearities of this type of linkage?

Thanks in advance!

Simulink cosimulation mechanism control HELP