Fuzzy logic based attitude control of the spacecraft X-38 along a nominal re-entry trajectory

Fuzzy logic control techniques are investigated for applications in the int elligent re-entry flight control of the ESA-NASA crew return vehicle. Three PD-Mamdani fuzzy controllers are constructed to control the inner-loop att itude dynamics, simulated by a fully nonlinear 3 degree-of-freedom simulato r of the CRV. Each controller uses an angle tracking error and its derivati ve to calculate a commanded control surface deflection of the simulator. Th e input-domains are partitioned with 5 membership functions, resulting in 2 5 fuzzy rules for each rule-base. The output-domains are partitioned with 9 membership functions. The Mamdani controllers use a standard max-min infer ence process and a fast center of area method to calculate the crisp contro l signals. Simulation results show the ability to track a reference traject ory with acceptable performance, though the real strength of a nonlinear fu zzy logic controller is yet to be proven with more demanding benchmark traj ectories. (C) 2001 Elsevier Science Ltd. All rights reserved.