A Singular Perturbation Theory-Based Composite Control Design for a Pump-Controlled Hydraulic Actuator with Position Tracking Error Constraint

Pump-controlled hydraulic actuators (PHAs) contain slow mechanical and fast dynamics, thus singular perturbation theory can be adopted in the control strategies of PHAs. In this article, we develop a theory-based composite approach for PHA with position tracking error constraint. Disturbance observers (DOBs) are used to estimate matched mismatched uncertainties online compensation. A sliding surface-like variable is proposed transform second-order subsystem into first-order subsystem. Consequently, constraint decomposed output stabilizing Slow laws easily designed without using backstepping technique, simplifying design reducing computational burden large extent. Theoretical analysis verifies that desired stability properties achieved by an appropriate selection parameters. Simulations experiments performed confirm efficacy practicability strategy.