  In this paper, we present necessary and sufficient conditions under which a
linear time-invariant (LTI) system is state feedback equivalent to a negative
imaginary (NI) system. More precisely, we show that a minimal LTI strictly
proper system can be rendered NI using full state feedback if and only if it
can be output transformed into a system, which has relative degree less than or
equal to two and is weakly minimum phase. We also considered the problems of
state feedback equivalence to output strictly negative imaginary systems and
strongly strict negative imaginary systems. Then we apply the NI state feedback
equivalence result to robustly stabilize an uncertain system with strictly
negative imaginary uncertainty. An example is provided to illustrate the
proposed results, for the purpose of stabilizing an uncertain system.
