Simulink Linearization

Extract linear time invariant (LTI) or linear parameter varying (LPV) models from Simulink using linearize and related APIs from Simulink Control Design.

When to Use

• Obtaining a linear model (tf, ss, zpk) from a Simulink model
• Batch linearization across operating points and parameter variations
• Building LPV models with ssInterpolant
• Debugging linearization results (zero gain, unexpected dynamics)
• Extracting multiple LTI systems with a single model compile

When NOT to Use

• Frequency response estimation from simulation, use simulink-frequency-response for frestimate-based fallback
• No Simulink model is involved

Workflow

The linearization pipeline has four stages. Not every task requires all stages.

1. Define I/O Points 2. Operating Point  →  3. Linearize  →  4. Debug  
    (root level/linio)   (findop/operspec)     (linearize)     (advisor) 

Stage 1: Define Linearization I/O Points

Determine I/O points using this decision sequence. Use the first case that applies:

Case A, IO points can be inferred from prompt or model context:

Use the first sub-case that matches:

1. User specifies explicit I/O signals or blocks (e.g., "from r to y") → define linio points. All linio points must reference a block's output port. If a candidate block has no output ports (Outport, Terminator, Scope) → trace upstream to find the source block and port with model_read.

   io = [linio(sprintf("%s/InputBlock", mdl), 1, "input"); ...
         linio(sprintf("%s/OutputBlock", mdl), 1, "output")];
   

2. User targets a specific block or subsystem (e.g., "linearize the Controller") → Use the block path as the io argument signaling linearize to perform open-loop linearization of the block

   io = sprintf("%s/Controller", mdl);
   

3. Model has existing linearization points → io = getlinio(mdl);, use if non-empty.