Nyquist diagram - stability

[powersys]

Consider an open loop transfer function G(s). Let say from Nyquist analysis, the closed system is predicted to be stable. Then, when a step input is applied to the closed-loop system, the natural response is found to be zero (or dies out) when time approaches infiniti. Therefore, the system is stable.

Without doing any analysis, can we say that the closed loop system will also be stable if the input is ramp input or parabolic input? Thanks.

 

[flatulent]

The steady state error for these two alternate inputs can be zero, a fixed value, or one growing with time depending on the order of the system.

 

[powersys]

The steady state error for these two alternate inputs can be zero, a fixed value, or one growing with time depending on the order of the system.

Is the system highlighted above G(s)? But from Nyquist analysis, the closed-loop system is found to be stable. Do you mean Nyquist analysis will not have a 'final say' whether the system is stable or not? The stability is still dependent on the type of input? Pls advise. Thanks.