Muticopters possess greater maneuverability and hovering over conventional single rotor helicopters that allows multirotor vehicles to be relatively simple in design yet highly reliable and maneuverable 23. Considering current market sizes, a diameter of 0.9 m is set as the maximum diameter of the aircraft sized here. Providing a margin of 150 lb then brings the maximum thrust output required to 350 lb.
This aircraft shall be able to output this thrust at about 50% power. The weight of the aircraft is generously assumed to be 50 lb for a total of 200 lb. To guarantee a better performance specification, a requirement of a 150 lb payload is set. The current world record for the heaviest payload lifted by a remote controlled multicopter is 134 lb 7.6 oz, according to Guinness World Records 22. The conceptual design is the starting point in systems engineering where a multitude of design configurations are evaluated for performance and robustness following a set of requirements 21. In the subsequent sections, the paper presents a systematic treatment of the robust design of such a vehicle (please refer to the appendix for variable definitions). Therefore, the main contribution this paper makes is to design the parameters (rather than the control) of the multirotor aircraft to make it robust against external disturbances. Therefore, it is of interest to explore designs for an aerial vehicle which allow it to perform its mission successfully despite the presence of uncertain environmental conditions like wind. Further, trajectory tracking was designed using robust control to decrease sensitivity to unmodeled dynamics and external disturbances 20.ĭespite this extensive research on the application of robust control to aerial vehicles, there has been no exploration of the design space for multirotor vehicles with respect to robustness. This controller was designed to be robust against coupling and non-linear dynamics, parametric uncertainties, and external disturbances. Multirotor aircraft controllers have been designed using robust control 18 where a hexarotor is designed using a linear quadratic regulator in conjunction with a robust compensator 19. Their applications are vast and include uses in earth science 11, search and rescue 12, wild fire suppression 13, law enforcement 14, border surveillance 15, industrial applications 16, and agriculture 17. Multirotor aircraft are becoming increasingly popular in both civilian, military, and corporate use. Therefore, a linear quadratic regulator-based controller was synthesized in 10 after feedback linearization the nonlinear air-breathing vehicle. Robust control is used in the design of hypersonic aircraft to control longitudinal motion because stability of aircraft at speeds above the speed of sound is very sensitive to environmental conditions 10. Aircraft attitude control has been performed with variation in the aircraft model involving weight and center of gravity 9. Robust control is applied to many dynamical systems and is very popular in flight control systems 7, 8. In control theory, robust control deals with designing a controller in the presence of variations or uncertainties either in the system itself or due to external disturbances 6. The first-order method of moments and Sigma-Point reduced quadrature are used to calculate the mean and variance of the evaluated performance for a fixed wing aircraft 5. In the field of robust aircraft design, the design of fixed wing aircraft using robust methods was explored 4.
Robust design methods such as the Taguchi design method are widely used and involve evaluating the parameters to be designed, designing the parameters using an orthogonal array, and performing analysis of variance using ANOVA and signal to noise ratios 3. For example, Response Surface Methodology was incorporated with the compromise Decision Support Problem 2. Procedures for robust design have been investigated in the literature. Robust design involves the task of designing a system in which performance variations due to both noise factors and control factors are minimized 1. The result is proof that the design choices discussed are in fact optimally robust. This research explores the design of physical parameters of an aerial vehicle to make it least sensitive to variations in the form of wind disturbances as an example.
The purpose of robust product design is to create a product that is as insensitive to internal and/or external variations as possible.
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