Mark Signals of Interest for Control System Analysis and
Design
Analysis Points
Whether you model your control system in MATLAB or Simulink, use analysis points to
mark points of interest in the model. Analysis points allow you to access internal signals,
perform open-loop analysis, or specify requirements for controller tuning. In the block
diagram representation, an analysis point can be thought of as an access port to a signal
flowing from one block to another. In Simulink, analysis points are attached to the
outports of Simulink blocks. For example, in the following model, the reference signal, r,
and the control signal, u, are analysis points that originate from the outputs of the
setpoint and C blocks respectively.Each analysis point can serve one or more of the following purposes:- Input — The software injects an additive input signal at an analysis point, for
example, to model a disturbance at the plant input. - Output — The software measures the signal value at a point, for example, to study the
impact of a disturbance on the plant output. - Loop Opening — The software inserts a break in the signal flow at a point, for
example, to study the open-loop response at the plant input.
You can apply these purposes concurrently. For example, to compute the open-loop
response from u to y, you can treat u as both a loop opening and an input. When you use
an analysis point for more than one purpose, the software applies the purposes in this
sequence: output measurement, then loop opening, then input.Mark Signals of Interest for Control System Analysis and Design