Time-delay compensation for networked hardware-in-the-loop simulation of a flight control system using polynomial prediction

Hardware-in-the-loop simulation is an effective approach for testing the electronic controller of a closed-loop control system within a computer-based real-time simulation of the rest of the system. In this paper, the pitch attitude hold mode controller of an aircraft vehicle is tested using hardware-in-the-loop simulation. A computer is used for real-time simulation of flight, and an electronic board is employed for controller implementation. The controller and the simulator are connected using a network protocol. The hardware-in-the-loop simulation can achieve unstable behavior or inaccurate results due to the time-delay of network connection. The maximum allowable delay bound in networked connection is derived using the method of delayed differential equations. The sufficient conditions for the stability of linear time-delay systems are given. The proof makes use of Lyapunov–Krasovskii functional and the condition is expressed in term of linear matrix inequalities. Therefore, a polynomial-based predictor is designed for the time-delay compensation of network connection. The consistency of the experimental real-time simulation and off-line simulation shows the applicability of the presented method for mitigating the effect of time-delay in the networked hardware-in-the-loop simulation. Also, the uncertainty of the model due to stability and control derivatives are considered for analyzing the stability of the networked hardware-in-the-loop simulation.