In this chapter, the input-nonaffine fully actuated system (FAS) controller structure is established for trajectory tracking and fault tolerance. From an unknown input-nonaffine FAS model, an observer-based control input dynamics is yielded, which ensures the low-power characteristics of the FAS controller. Both the observation error and tracking error eventually converge eventually, and the error bound can be adjusted to a tiny neighborhood around the origin. Moreover, for unknown input-nonaffine FASs with multiplicative actuator and sensor faults, a robust fault-tolerant control strategy for stabilization tasks is proposed to realize the ultimately uniformly bounded stability. The main results are proved theoretically and illustrated experimentally.