addmd (Model Predicitve Control Toolbox)

Adds one or more measured disturbances to a plant model in the MPC mod format. Used to allow for feedforward compensation in MPC.

Syntax

model = addmd(pmod,dmod)

Description

The disturbance model contained in dmod adds to the plant model contained in pmod to form a composite, model, with the structure given in the following block diagram:

pmod, dmod and model are in the MPC mod format (see mod in the online MATLAB Function Reference for a detailed description). You would normally create pmod and dmod using either the tfd2mod, ss2mod or th2mod functions.

addmd is a specialized version of paramod. Its main advantage over paramod is that it assumes all the inputs to dmod are to be measured disturbances. This saves you the trouble of designating the input types in a separate step.

Example

See ss2mod for an example of the use of this function.

Algorithm

addmd converts pmod and dmod into their state-space form, then uses the mpcparal function to build the composite model.

Restrictions

pmod and dmod must have been created with equal sampling periods and number of output variables.
pmod must not include measured disturbances, i.e., its mod format must specify nd = 0.
All inputs to dmod must be classified as manipulated variables. (They will be reclassified automatically as measured disturbances in model.) So the mod format of dmod must specify nd = nw = 0 (which is the default for all model creation functions).