Procedure

1. Download the Analysis folder from the sbhs website. It will be available under downloads section. Download the file for SBHS Analysis Code (local & virtual). The name of the file is scilab_codes_analysis. The download will be in zip format. Extrat the downloaded zip file. You will get a folder scilab_codes_analysis.
2. Open the scilab_codes_analysis folder and then locate and open the folder Step_Analysis.
3. Open the Kp-tau-order2 folder.
4. Copy the step test data file to the folder Kp-tau-order2.
5. Change the Scilab working directory to Kp-tau-order2 folder under Step_Analysis folder.
6. Open the file secondorder.sce in scilab editor and enter the name of the data file (with extention) in the filename field.
7. Save and run this code and obtain the plot as shown in figure 2.5.

$$G_{s}(s) = \frac {0.235}{(57.39s+1)(1s+1)}$$ (2.15)

Figure 2.5: Output of the Scilab code secondorder.sce

The fit is much better now. In particular, the initial inflexion is well captured by this second order transfer function.