**6. Digital control root locus**

78 E-Learning – Organizational Infrastructure and Tools for Specific Areas

precision the sensors could have which is quite poor. After this experiment the sensitivity was increased by a factor of 2 to achieve greater accuracy in position and velocity values.

The gain value used in this experiment was 2, and the step input was 90 degrees.

Fig. 6. Simulated results versus real data - continous.

Fig. 7. Simulated results versu real data - digital.

In this experiment Control System Toolbox in Matlab, more especially 'sisotool' was used to design a Root Locus Controller by applying a gain and placing poles and zeros. Several designs were devised that looked robust in theory, but performed not as well. The difference of theory and practice became prominent as the solution required greater control effort. While the control design technique was intended for linear systems, the effect of saturation was becoming more outstanding in the real world.

Fig. 8. Root locus plot of motor position control.

One of the working designs is presented. The control effort was designed to be kept below the saturation point; however the same quantization error that occurred in Proportional Control experiment was also observable here as well.
