This paper addresses the problem of approximation-free prescribed performance control (PPC) for a class of non-triangular pure-feedback nonlinear dynamics whose nonaffine function of each subsystem is relaxed to rely on the whole state vector. The assumption made in this work is far more relaxed than all the available works in the sense that some commonly used Lipschitz condition or setting bounding function are never involved and only the continuity of nonlinearities are required. Furthermore, the proposed low-complexity PPC is simplified because neither approximators (neural networks and fuzzy logic systems) nor adaptation technique are embeded in the control design. By utilizing the barrier functions, some transient and steady state performances can be also preserved, while guaranteeing the closed-loop stability. Simulation results of hypersonic flight vehicles (HFVs) dynamics eventually validate the effectiveness of the proposed methodology.INDEX TERMS Non-triangular structural, prescribed performance, pure-feedback, barrier function, hypersonic flight vehicles.
In the hardware-in-the-loop simulation, the goal of electric loading is to realize the accurate tracking of the torque signal and test the performance of the aircraft actuator system. For some high dynamic aircraft, it is necessary to reduce the influence of the surplus torque to increase the system frequency band. This paper introduces a new electric loading system which adopts a double-loop servo motor as the torque loading mechanism. It applies two loops to track the position of the rudder and the aerodynamic load spectrum respectively. For the purpose of reducing the disturbance between two loops of the scheme, a two-DOF H∞ robust controller is designed, which improves the robustness of the system effectively. The simulation results show that the new system increases the upper limit of 25 Hz frequency band of the traditional single-loop system with PID control to the maximum of 40 Hz. The double-loop system thereby meets the technical requirements of the hardware-in-the-loop simulation experiment for high dynamic aircrafts.
The electric motor drive load simulator can simulate the hinge torque of the steering gear during the flight of the aircraft, which is one of the key equipment of the servo test. This paper bases on the composition and working principle of the electric load simulator, and based on the Narendra model reference adaptive control theory, the reference model of the controlled object is designed. Considering the large step disturbance of steer gear, the load simulator system the paper presented is simulated. The results show that the model can increase the bandwidth of the load system from 20 Hz to 30 Hz, realize fast, high-precision control of the electric load simulator, and improve the system's anti-perturbation performance effectively.
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