Position Control of a Single-Rod Electro-Hydrostatic Actuator Experiencing a Leaky Piston Seal

Single-rod cylinders are generally employed in electro-hydrostatic actuators (EHAs). A condition that is difficult to detect and could degrade the performance in single-rod EHAs, is the faulty cylinder piston seal. It causes internal leakage from one chamber of the actuator to another. In this work, a position controller with tolerance to actuator internal leakage is synthesized for a single-rod EHA using quantitative feedback theory (QFT). The controller is also robust to different loading and environmental stiffnesses. The ability of the controller is compared with another QFT controller that is synthesized without considering leakage fault. The simulation results show that the QFT fault-tolerant controller can meet prescribed specifications despite internal leakage up to 8.6 L/min.