[x, u, y, dx] = trim(model)
[x, u, y, dx] = trim(model, x0, u0)
| Parameter | Description |
|---|---|
| model | a loaded system (name or handle) or the path to a .nflow file. |
| x0 | optional starting continuous state (length nx) for the search. |
| u0 | optional fixed inputs (length nu). External-port Label Source blocks. |
| Parameter | Description |
|---|---|
| x | the equilibrium continuous state. |
| u | the inputs at the solution (equal to u0). |
| y | the outputs at the solution. |
| dx | the state derivative at the solution; its norm measures how close to equilibrium. |
trim finds a steady-state (equilibrium) operating point of model: a continuous state x at which xdot = f(x, u0) = 0 for the fixed inputs u0.
It solves the equation by a Newton iteration on the state Jacobian A = d(xdot)/dx computed by linmod, starting from x0. For a linear model the equilibrium is x = -A\(B*u0), reached in one step.
d.blocks = { ...
struct('id','u','type','labelSource','inputs',0,'outputs',1,'params',struct('label','u','isExternalPort',true)), ...
struct('id','ss','type','stateSpace','inputs',1,'outputs',1,'params',struct('A',-2,'B',1,'C',1,'D',0)), ...
struct('id','y','type','labelSink','inputs',1,'outputs',0,'params',struct('label','y')), ...
struct('id','sc','type','scope','inputs',1,'outputs',0,'params',struct()) };
d.connections = { ...
struct('from','u','to','ss','fromIndex',0,'toIndex',0), ...
struct('from','ss','to','y','fromIndex',0,'toIndex',0), ...
struct('from','ss','to','sc','fromIndex',0,'toIndex',0) };
f = [tempdir(), 'trim_demo.nflow'];
fid = fopen(f,'wt'); fwrite(fid, jsonencode(d)); fclose(fid);
[x, u, y, dx] = trim(f, 0, 2) % x = 1 (xdot = 0)| Version | Description |
|---|---|
| 1.0.0 | initial version |