The relative degree (RD) approach is a powerful tool, for obtaining a system’s input-output dynamics of an output tracking controller design with minimum phase dynamics. Designs using RD alone can fail due to insufficient control authority in minimum phase systems, and instability of internal/zero dynamics attributed to non-minimum phase systems. Generalized RD (GRD) in minimum phase systems can identify parasitic control terms (PCTs). An Alternate GRD (AGRD) is investigated, to determine the impact of discarding these PCTs. A novel definition for Practical GRD (PGRD) is proposed and used in concert with Sliding Mode Control (SMC) compensating system perturbations in minimum phase systems. Using known GRD in nonminimum phase systems allows for internal dynamics reduction. However, in-stability emerging in the corresponding control dynamic extension defeats any output tracking controller design. A novel methodology of using GRD for designing continuous SMC in nonminimum phase systems is presented. An approach for generating bounded solutions of the unstable dynamic extension is proposed and used in concert with SMC, allowing for a viable control design for nonminimum phase systems. The efficacy of the proposed GRD-based approaches is demonstrated for both minimum and nonminimum phase missile attitude control problems
