A directional control system for UCAV automatic takeoff roll
Aircraft Engineering and Aerospace Technology
ISSN: 0002-2667
Article publication date: 18 January 2013
Abstract
Purpose
The purpose of this paper is to develop a directional and roll control system for unmanned combat air vehicle (UCAV) automatic takeoff roll, with the objective of keeping the UCAV along the runway centerline and keeping the wings level, especially when there is a crosswind.
Design/methodology/approach
The nonlinear model of the UCAV during takeoff roll is established. The model is linearized about the lateral‐directional equilibrium point at different forward speeds. The approximate directional model and roll model are extracted using time‐scale decomposition technique. Then the directional control law and roll control law are developed using gain scheduling approach. Nose wheel steering, differential brake and rudder are used as the primary directional control device at low, medium and high speeds, respectively, according to both the qualitative and quantitative analysis of their control effectiveness at different speeds. A priority matrix is developed to determine the secondary control device which is used if the primary control device fails, thus the directional control system can have a certain degree of fault tolerance.
Findings
This work developed the directional control law and roll control law by using gain scheduling approach. Experimental results verified that the developed directional and roll control system has high robustness and satisfactory fault tolerance: it can guarantee a safe takeoff under a 50 ft/sec crosswind, even if one directional control device fails, which satisfies the relevant criteria in MIL‐HDBK‐1797.
Practical implications
The directional and roll control system developed can be easily applied to practice and can steer the UCAV during takeoff roll safely, which will considerably increase the autonomy of the UCAV.
Originality/value
The paper shows how time‐scale decomposition technique is employed to extract the approximate directional model and roll model, which simplifies model analysis and control law design. A fault‐tolerant directional control system is designed to improve safety during takeoff.
Keywords
Citation
Zhang, Y. and Duan, H. (2013), "A directional control system for UCAV automatic takeoff roll", Aircraft Engineering and Aerospace Technology, Vol. 85 No. 1, pp. 48-61. https://doi.org/10.1108/00022661311294076
Publisher
:Emerald Group Publishing Limited
Copyright © 2013, Emerald Group Publishing Limited