functionstepResponse

Calculate the step time response of a discrete state space system

Extends from Modelica_LinearSystems2.Internal.timeResponseMask_discrete (Declares the common structure for the set of response functions).

Information

Syntax

      (y) = DiscreteStateSpace.Analysis.stepResponse(dss)
(y, t, x) = DiscreteStateSpace.Analysis.stepResponse(dss, tSpan)

Description

Function stepResponse calculates the step response of a discrete state space system. Starting at x(t=0)=0 and y(t=0)=C*x0 + D*u0, the outputs y and the states x are calculated for each time step t=k*dss.Ts. The function call

DiscreteStateSpace.Analysis.stepResponse(dss, tSpan)

gives the same result as

DiscreteStateSpace.Analysis.timeResponse(response=Types.TimeResponse.Step, dss, tSpan, x0=fill(0,size(ss.A,1))).

Note that an appropriate step response of a discrete system that is comparable to the step response of the corresponding continuous system requires the "StepExact" conversion from continuous system to discrete system.

Example

  Modelica_LinearSystems2.DiscreteStateSpace dss=Modelica_LinearSystems2.DiscreteStateSpace(
    A=[0.904837418036 ],
    B=[0.095162581964],
    C=[2],
    D=[0],
    B2=[0],
    Ts=0.1,
    method = Modelica_LinearSystems2Types.Method.StepExact);

  Real tSpan= 0.4;

  Real y[5,1,1];
  Real t[5];
  Real x[5,1,1]

algorithm
  (y,t,x) := Modelica_LinearSystems2.DiscreteStateSpace.Analysis.stepResponse(dss,tSpan);
//  y[:,1,1]={0, 0.19, 0.3625, 0.518, 0.659}
//         t={0, 0.1, 0.2, 0.3, 0.4}
//  x[:,1,1]={0, 0.0952, 0.1813, 0.2592, 0.33}

See also

DiscreteStateSpace.Analysis.timeResponse, StateSpace.Analysis.stepResponse

Inputs

TypeNameDefaultDescription
DiscreteStateSpacedss (from timeResponseMask_discrete)Discrete state space system
RealtSpan (from timeResponseMask_discrete)0Simulation time span [s]

Outputs

TypeNameDefaultDescription
Real[:,size(dss.C, 1),size(dss.B, 2)]y (from timeResponseMask_discrete)Output response: (number of samples) x (number of outputs) x (number of inputs)
Real[:]t (from timeResponseMask_discrete)Time vector: (number of samples)
Real[:,size(dss.A, 1),size(dss.B, 2)]x_discrete (from timeResponseMask_discrete)State trajectories: (number of samples) x (number of states) x (number of inputs)