Adaptive Control of the NASA Generic Transport Model Using Retrospective Cost Optimization

We provide a detailed description of retrospective-cost based adaptive control, which is a discrete-time adaptive control law for stabilization, command following, and disturbance rejection that is effective for systems that are unstable, MIMO, and/or nonminimum phase. The adaptive control algorithm includes guidelines concerning the modeling information needed for implementation. This information includes the sign of the high-frequency gain as well as the nonminimum-phase zeros. Except when the plant has nonminimum-phase zeros whose absolute value is less than the plant’s spectral radius, the required information can be approximated by a sufficient number of Markov parameters. No additional information about the poles or zeros need be known, and no matching conditions are required. We apply this adaptive control technique to NASA’s Generic Transport Model to illustrate disturbance rejection under unknown, reduced controller authority.