A new robust fuzzy method for unmanned flying vehicle control

A new general robust fuzzy approach was presented to control the position and the attitude of unmanned flying vehicles(UFVs). Control of these vehicles was challenging due to their nonlinear underactuated behaviors. The proposed control system combined great advantages of generalized indirect adaptive sliding mode control(IASMC) and fuzzy control for the UFVs. An on-line adaptive tuning algorithm based on Lyapunov function and Barbalat lemma was designed, thus the stability of the system can be guaranteed. The chattering phenomenon in the sliding mode control was reduced and the steady error was also alleviated. The numerical results, for an underactuated quadcopter and a high speed underwater vehicle as case studies, indicate that the presented adaptive design of fuzzy sliding mode controller performs robustly in the presence of sensor noise and external disturbances. In addition, online unknown parameter estimation of the UFVs, such as ground effect and planing force especially in the cases with the Gaussian sensor noise with zero mean and standard deviation of 0.5 m and 0.1 rad and external disturbances with amplitude of 0.1 m/s2 and frequency of 0.2 Hz, is one of the advantages of this method. These estimated parameters are then used in the controller to improve the trajectory tracking performance.

Transonic Rudder Buzz on Tailless Flying Wing UAV

Transonic rudder buzz responses based on the computational fluid dynamics or computational structural dynamics(CFD/CSD)loosely method are analyzed for a tailless flying wing unmanned aerial vehicle(UAV).The Reynolds-averaged Navier-Stokes(RANS)equations and finite element methods based on the detailed aerodynamic and structural model are established,in which the aerodynamic dynamic meshes adopt the unstructured dynamic meshes based on the combination of spring-based smoothing and local remeshing methods,and the lower-upper symmetric-Gauss-Seidel(LU-SGS)iteration and Harten-Lax-van Leer-Einfeldt-Wada(HLLEW)space discrete methods based on the shear stress transport(SST)turbulence model are used to calculate the aerodynamic force.The constraints of the rudder motions are fixed at the end of structural model of the flying wing UAV,and the structural geometric nonlinearities are also considered in the flying wing UAV with a high aspect ratio.The interfaces between structural and aerodynamic models are built with an exact match surface where load transferring is performed based on 3Dinterpolation.The flying wing UAV transonic buzz responses based on the aerodynamic structural coupling method are studied,and the rudder buzz responses and aileron,elevator and flap vibration responses caused by rudder motion are also investigated.The effects of attack,height,rotating angular frequency and Mach number under transonic conditions on the flying wing UAV rudder buzz responses are discussed.The results can be regarded as a reference for the flying wing UAV engineering vibration analysis.

The stability of rolling motion of hypersonic vehicles with slender configuration under pitching maneuvering

The configurations of near space hypersonic flying vehicles are considerably different from those of conventional aircrafts.Their configurations are relatively slender;hence their moment of inertia around the longitudinal axis is much smaller than those around the other two axes,resulting in strong coupling of rotations around the three axes.Thus,the stability analysis of rolling motion for such flying vehicles is more complicated than those for conventional aircrafts,and there is no available result of stability analysis which can readily be applied to such cases.This paper is mainly concerned with the stated problem.Considering the practical situation,our investigation is targeted a slightly simpler problem,namely the rolling stability of flying vehicle under known pitching motion.The stability criterion of rolling motion is obtained with and without lateral motions.We also conducted numerical simulation for the pitching-rolling coupled motions of flying vehicles by solving Navier-Stokes equations coupled with dynamic equations of flight.The results of simulation agree well with those of theoretical analysis and experiments.

A path planning algorithm for autonomous flying vehicles in cross-countryenvironments with a novel TF-RRT^(*) method

Autonomous flying vehicles(AFVs)are promising future vehicles,which have high obstacle avoidance ability.To plan a feasible path in a wide range of cross-country environments for the AFV,a triggered forward optimal rapidly-exploring random tree(TF-RRT^(*))method is proposed.Firstly,an improved sampling and tree growth mechanism is built.Sampling and tree growth are allowed only in the forward region close to the target point,which significantly improves the planning speed;Secondly,the driving modes(ground-driving mode or air-driving mode)of the AFV are added to the sampling process as a planned state for uniform planning the driving path and driving mode;Thirdly,according to the dynamics and energy consumption models of the AFV,comprehensive indicators with energy consumption and efficiency are established for path optimal procedures,so as to select driving mode and plan driving path reasonably according to the demand.The proposed method is verified by simulations with an actual cross-country environment.Results show that the computation time is decreased by 71.08%compared with Informed-RRT^(*)algorithm,and the path length of the proposed method decreased by 13.01%compared with RRT^(*)-Connect algorithm.

Mixed H_2/H_∞ Control Using a Fuzzy Singularly Perturbed Model with Multiple Perturbation Parameters for Gust Load Alleviation

This paper presents a mixed H21H∞ control using fuzzy singularly perturbed model （FSPM） with multiple perturbation parameters. Since FSPM with multiple perturbation parameters is an extension of models with a single perturbation parameter, the theoretical results are applicable to a larger class of systems described by multiple time scale nonlinear models, such as flying aircraft and flexible space robots. The parameter-independent solution of the mixed H21H∞ controller was obtained in the form of linear matrix inequalities （LMIs）. The application of this approach to gust load alleviation of a flying vehicle verifies its effectiveness and flexibility.