High performance direct torque control of electrical aerodynamics load simulator using adaptive fuzzy backstepping control

Electrical load simulator is hardware in the loop simulator used to exert real-time aerodynamics loads on the servo actuation system of a flight vehicle under test according to flight conditions. This article investigates direct torque control of electrical load simulator system using adaptive fuzzy backstepping method. To analyze the effect of extra torque disturbance on electrical load simulator system, detailed mathematical formulations are derived. Considering practical aspects of the proposed method, state vector is estimated using a state predictor, and parameters of the system are estimated using algebraic method. Fuzzy logic system is used to estimate extra torque disturbance acting on electrical load simulator system, but the approximation error may not converge to zero, which may affect control performance. Similarly, the parameters of the system may vary with time; thus the lumped disturbance due to time variation of parameters and fuzzy approximation error is compensated using adaptive control law derived based on estimated error dynamics between actual plant and state predictor. Moreover, to improve transient response, a novel saturation function-based transient performance controller is introduced. The performance of the proposed control is verified using extensive numerical simulations.