the CONTSID toolbox

Dynamic models of physical systems are obtained in terms of differential equations or transfer functions in continuous-time domain (CT). They are native to CT domain because the physical laws on which they are based are in CT domain. These models can be transformed into workable discrete time (DT) by appropriate sampling. Therefore, identification of CT models from their input-output data is of considerable importance in several areas including control and fault diagnosis. Methods to identify DT models are available but transformation of the DT models into CT is not a trivial issue. Also, the indirect route through the identification of DT models to obtain CT models is not, in general, as effective as the direct route in which CT models are obtained directly from input-output data. Several methods are by now well established to address the problem of direct identification of CT models. However, as far as we know, there is no toolbox that serves the cause of direct time-domain identification of CT systems.

The CONtinuous-Time System IDentification (CONTSID) toolbox is intended to fill this gap. The CONTSID toolbox contains routines for the direct CT model identification of linear time-invariant SISO, MISO and MIMO systems from regularly or irregularly sampled input/output data. The toolbox is compatible with Matlab 7.x and has been given a similar setup to the Mathwork's System Identification toolbox. Two Matlab toolboxes are required: the Control toolbox and the System Identification toolbox.

The latest version 5.0 (released in November 23, 2009) of the CONTSID toolbox includes the following four major additions:
• - it includes a flexible Graphical User Interface (GUI)
• - it supports errors-in-variables CT transfer function model identification;
• - it provides routines to estimate linear CT transfer function model in closed loop;
• - it includes methods to identify nonlinear CT Hammerstein models.

The GUI for the CONTSID toolbox can be run by the following command
- contsidgui: which opens the main window of the GUI.

The demonstration programs which illustrate the use of the toolbox as well as the latest developments can be run by entering the following command:
-idcdemo

Please contact the authors if you want to have more information about the latest version of the CONTSID toolbox. Any feedback is also welcome.