**5. Conclusions**

In this chapter, a systematic way for constructing simultaneous *H*∞ state feedback controllers of nonlinear control systems in strict-feedback form is proposed. It is shown that the existence of common CSFs guarantees the existence of simultaneous *H*∞ controllers. An explicit formula for constructing simultaneous *H*∞ controllers is derived. The simulation example is given for verifying the theoretical results. The simulation results show, as expected, that the designed controller can simultaneously stabilize the considered systems and such that all closed-loop systems satisfy the specified disturbance attenuation requirement. Possible further works include considering nonlinear control systems in more general forms, applying the approach to time-varying case, and considering the output feedback case.
