1. Parameter *a* in *W*S

To analyze the influence of the parameter *a* on weighting function *W*S, the other parameters in the weightings were kept unchanged. By changing *a* from 0 to 3.5, the dynamics were calculated via the step response, which is shown in Figure 5. It is seen from the figure that with the increase in parameter *a*, the settling time grew rapidly, while the overshoot decreased quickly. The steady-state error almost remained the same. Hence, it is recommended that a small positive value should be used for parameter *a*.

**Figure 5.** Effect of parameter *a* on *W*S. (**a**) Settling time; (**b**) overshoot; (**c**) steady-state error.
