ABSTRACT
The SDRE method is an emerging controller design methodology. It represents a systematic way of designing nonlinear feedback controllers for a broad class of nonlinear problems. It has been used in [2] to produce advanced guidance algorithms, used in [3] for autopilot design, used in [4] for a nonlinear benchmark problem design and is briefly mentioned in [6]. In the SDRE approach, the nonlinear system is first brought to a linear structure having state-dependent coefficients (SDC). In the case of full state information, a state-dependent Riccati equation (SDRE) is then solved at each point x along the trajectory to obtain the nonlinear, feedback controller u = — R_ 1(jr)5r (jc)P(jc)x, where P(x) is the solution of the SDRE. For output feedback, two SDRE’s have to be solved in order to construct
the nonlinear control dynamics. The SDRE technique is analysed in detail in [1] where, in addition to nonlinear regulation, minimum energy (nonlinear H ^ ) control is also addressed. The nonlinear SDRE #2 method can be obtained from the Hæ formation in [1] by letting γ -> oo. The resulting formulation is presented below.
