Constraint enforcement methods for command governor based adaptive control of uncertain dynamical systems

Recently, research has been conducted in order to improve the transient behavior of adaptively-controlled uncertain nonlinear dynamical systems. In this paper, an adaptive control architecture is extended in order to achieve predictable transient performance in the presence of state constraints. The methodology at hand is based on a robust command governor framework, which is a dynamical system adjusting the trajectory of a given command in order to track a certain desired closed-loop reference model both in transient time and steady-state. Specifically, the command, which is applied on the reference model and the actual system, is changed by the command governor framework for improved transient performance with respect to classical adaptive control schemes and by a constraint enforcement command in order to keep the states within pre-defined bounds. The constraint enforcement method here is able to handle state constraints in the range space of the control input matrix. The application of command governor and constraint enforcement on nonlinear dynamic inversion controllers is discussed and an example is implemented using a helicopter model for illustration purposes. An example using the wing rock dynamics shows the performance and additional methods for enforcing state constraints outside of the range space of the input matrix are also introduced.