*5.2. Loading System Verification*

The feasibility of the designed *H*∞ controller was verified first. The step response is given in Figure 20. It is seen in the figure that there was a pure delay in the system and no steady-state error. The rise and settling times were 0.018 and 0.048 s, respectively. The time of first achieving the command was 0.025 s. It seems that the *H*∞ controller could not complete the RTHS. However, the step response is very rigorous, so the additional test was carried out to further verify the dynamic performance.

A sinusoidal signal was discretized with a sampling time of 0.02 s, which was used as the command signal. The response is shown in Figure 21. It is seen in the figure that at the end of each step, the measurement displacements were in good agreemen<sup>t</sup> with the command, indicating that the *H*∞ controller was suitable for RTHS.

**Figure 20.** Step response with *H*∞ controller.

**Figure 21.** Tracking performance under sinusoidal signal.
