plotSection

Visualize explicit MPC control law as 2-D sectional plot

Syntax

plotSection(empcobj,plotParams)

Description

plotSection(empcobj,plotParams) displays a 2-D sectional plot of the piecewise affine regions used by an explicit MPC controller. All but two of the control law’s free parameters are fixed, as specified by plotParams. The two remaining variables form the plot axes. By default, the empcobj.Range property sets the bounds for these axes.

Examples

Specify Fixed Parameters for 2-D Plot of Explicit Control Law

Define a double integrator plant model and create a traditional implicit MPC controller for this plant. Constrain the manipulated variable to have an absolute value less than 1.

plant = tf(1,[1 0 0]);
mpcobj = mpc(plant,0.1,10,3);

-->"Weights.ManipulatedVariables" is empty. Assuming default 0.00000.
-->"Weights.ManipulatedVariablesRate" is empty. Assuming default 0.10000.
-->"Weights.OutputVariables" is empty. Assuming default 1.00000.

mpcobj.MV = struct('Min',-1,'Max',1);

Define the parameter bounds for generating an explicit MPC controller.

range = generateExplicitRange(mpcobj);

-->Converting the "Model.Plant" property to state-space.
-->Converting model to discrete time.
   Assuming no disturbance added to measured output #1.
-->"Model.Noise" is empty. Assuming white noise on each measured output.

range.State.Min(:) = [-4;-4];
range.State.Max(:) = [ 4; 4];
range.Reference.Min(:) = -2;
range.Reference.Max(:) = 2;
range.ManipulatedVariable.Min(:) = -1.1;
range.ManipulatedVariable.Max(:) = 1.1;

Create an explicit MPC controller.

empcobj = generateExplicitMPC(mpcobj,range);

Regions found / unexplored:       19/       0

Create a default plot parameter structure, which specifies that all of the controller parameters are fixed at their nominal values for plotting.

plotParams = generatePlotParameters(empcobj);

Allow the controller states to vary when creating a plot.

plotParams.State.Index = [];
plotParams.State.Value = [];

Fix the manipulated variable and reference signal to 0 for plotting.

plotParams.ManipulatedVariable.Index(1) = 1;
plotParams.ManipulatedVariable.Value(1) = 0;
plotParams.Reference.Index(1) = 1;
plotParams.Reference.Value(1) = 0;

Generate the 2-D section plot for the explicit MPC controller.

plotSection(empcobj,plotParams)

ans = 
  Figure (1: PiecewiseAffineSectionPlot) with properties:

      Number: 1
        Name: 'PiecewiseAffineSectionPlot'
       Color: [1 1 1]
    Position: [348 376 583 437]
       Units: 'pixels'

  Use GET to show all properties

Input Arguments

empcobj — Explicit MPC controller

explicit MPC controller object

Explicit MPC controller for which you want to create a 2-D sectional plot, specified as an Explicit MPC controller object. Use generateExplicitMPC to create an explicit MPC controller.

plotParams — Parameters for sectional plot

structure

Parameters for sectional plot of explicit MPC control law, specified as a structure. Use generatePlotParameters to create an initial structure in which all the parameters of the controller are fixed at their nominal values. Then, modify this structure as necessary before invoking plotSection. See generatePlotParameters for more information.

Version History

Introduced in R2014b