2.00     2.50
TIME (SECONDS)


1.50     2.M     2.S0
    TIME (SECONDS)


(a) Tracking error


Figure 7-20.


Manipulator's response: ref. = 3.0 Hz sinusoid with amplitude of 10 ; dist. = 4.5 Hz sinusoid with amplitude of 50 N; I.M. frequencies = 0 Hz, 3.0 Hz, and 4.5 Hz