Output Feedback Controls of a Flexible Wing Under Unknown Constraint References

The problem of output constraints for a flexible wing system is discussed in this paper, taking into account that all constraint references come from an exosystem with unknown initial values. A partial differential equation-ordinary differential equation (PDE-ODE) coupled observer is developed for exponential estimation of the uncertain constraints. An observer-based nonlinear control method is proposed to restrain the bending and twisting displacements. Numerical simulation is carried out to demonstrate the effectiveness of the designed controls.