Stability robustness improvement using constrained optimization techniques

In a multiloop feedback control system, stability margin improvement by singular value shaping cab be achieved with a noise adjustment procedure. A direct method for shaping the singular value spectrum using a constrained optimization technique is described. The design algorithm minimizes a standard linear-quadratic Gaussian performance index while it tries to satisfy minimum singular value constraints at the plant input, output, or both. Selected parameters of a stabilizing control law are used as the design variables. The capabilities of this method are demonstrated using a two-output system, which represents a drone aircraft and its lateral attitude control system.