ESO-based adaptive full state constraint control of uncertain systems and its application to hydraulic servo systems

In this paper, the control problem of a class of nonlinear systems with uncertainties and full state constraints is investigated and a full state constraint controller with parameter estimation and disturbance compensation is designed. Adaptive control for parametric uncertainties and extended state observer for uncertain nonlinearities are integrated into the barrier Lyapunov function-based full state constraint control via backstepping design, ensuring the nonviolation of full state constraints and the stability of the closed-loop system concurrently. With the proposed controller, all states are constrained within defined boundaries even with large uncertainties in the system and improved tracking performance can be achieved. In addition, asymptotic tracking is realized when the uncertain nonlinearities are time-invariant. Finally, the application of the proposed controller to hydraulic servo systems is carried out to demonstrate its validity.