Force tracking control of an electro-hydraulic control loading system on a flight simulator using inverse model control and a damping compensator

The electro-hydraulic control loading system (EHCLS) of a flight simulator is mainly used to simulate the force feel of flying a real airplane. A double-loop model, including control and hydraulic mechanism of the EHCLS, is established and its force–displacement impedance is analysed to evaluate force tracking performances and its stability. An approximated feed-forward inverse model controller is designed using a zero phase error compensation method for expanding the frequency bandwidth of the inner loop because the identified force closed-loop model is a nonminimum phase system and its direct inverse model is unstable. Modelling error between the designed feed-forward inverse model and the actual plant is discussed and a damping compensator is presented to increase stability of the EHCLS. Theoretical analysis, simulation and experimental results show that the control methods presented are feasible and can effectively improve force feel fidelity and stability of the EHCLS.