review

Examine MPC controller for design errors and stability problems at run-time

Syntax

review(mpcobj)

Description

review(mpcobj) checks for potential design issues in the Model Predictive Controller mpcobj and generates a report. review performs the following diagnostic tests:

  • Is the optimal control problem well defined?

  • Is the controller internally stable?

  • Is the closed loop system stable when no constraints are active and there is no model mismatch?

  • Is the controller able to eliminate steady-state tracking error when no constraints are active?

  • Is there a likelihood that constraint definitions will result in an ill-conditioned or infeasible optimization problem?

  • If the controller were used in a real-time environment, what memory capacity would be needed?

Use review iteratively to check your initial MPC design or whenever you make substantial changes to mpcobj. Make the recommended changes to your controller to eliminate potential problems. review does not modify mpcobj.

Input Arguments

mpcobj

Non-empty Model Predictive Controller (mpc) object

Examples

Examine an MPC Controller for Design Errors and Stability Problems

Create a Model Predictive Controller. For this example, use a controller with hard upper and lower bounds on the manipulated variable and its rate-of-change.

Plant = tf(1, [10 1]);
ts = 2;
MPCobj = mpc(Plant,ts);

MV = MPCobj.MV;
MV.Min = -2;
MV.Max =  2;
MV.RateMin = -4;
MV.RateMax =  4;
MPCobj.MV = MV;
-->The "PredictionHorizon" property of "mpc" object is empty. Trying PredictionHorizon = 10.
-->The "ControlHorizon" property of the "mpc" object is empty. Assuming 2.
-->The "Weights.ManipulatedVariables" property of "mpc" object is empty. Assuming default 0.00000.
-->The "Weights.ManipulatedVariablesRate" property of "mpc" object is empty. Assuming default 0.10000.
-->The "Weights.OutputVariables" property of "mpc" object is empty. Assuming default 1.00000.

Review the design.

review(MPCobj)

review flags the potential constraint conflict that could result if you applied this controller to a real process.

Examine the warning by clicking Hard MV Constraints.

Alternatives

review automates certain tests that you can perform at the command line.

To test for steady-state tracking errors, use cloffset.

To test the internal stability of a controller, check the eigenvalues of the mpc object. Use ss to convert the mpc object to a state-space model and call isstable.

More About

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Tips

  • If you design your controller using MPC Design Tool, export the controller to the MATLAB® Workspace, and analyze it using review.

  • review cannot detect all possible performance factors. So, additionally test your design using techniques such as simulations.

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