A special redefinition output variable,which makes the relative degree of the system be zero,is presented for the ship s straight-line tracking nonlinear system.

Based on the input-output linearization technique,a redefinition output variable and the corresponding state feedback control law are presented for the nonlinear mathematical model of ship′s straight-line tracking control system.

Then, based on the input-output linearization technique, a state feedback control law, which forces an underactuated ship to asymptotically track a prescribed straight line, is developed using the idea of redefinition output variable.

In order to solve the non-minimum phase problem of the output of missile normal overload,an output-redefinition technique was adopted.

The systems are transformed into normal form through coordination change, then output-redefinition approach is adopted to design the modified systems output and desired output.

Output-redefinition approach is adopted to design integral-type sliding mode control law,by which the nonminimum phase problem of original system is resolved,and the tracing of original system output is granteened.

A sliding surface is defined as a new output based on the idea of output redefinition,thus the overload system of missile with the characteristic of non-minimum phase can be transformed into minimum-phase system by tuning the parameters of the sliding surface,and a sliding-mode controller can be designed.

In this paper,we used output redefinition method and design appropriate parameter to make system s zero dynamic be stable.

A sliding-mode controller was designed based on the output redefinition for the overload system of missile with non-minimum phase characteristic.

The design of combinatorial logical circuit with many output variables is more complex than that with one output variable,because of the more output variables.