The Unmanned Aerial Vehicles (UAVs) become more and more popular due to various potential application fields. This paper studies the distributed leader-follower formation flight control problem of multiple UAVs with uncertain parameters for both the leader and followers. This problem has not been addressed in the literature. Most of the existing literature considers the leader-follower formation control strategy with parametric uncertainty for the followers. However, they do not take the leader parametric uncertainty into account. Meanwhile, the distributed control strategy depends on less information interactions and is more likely to avoid information conflict. The dynamic model of the UAVs is established based on the aerodynamic parameters. The establishment of the topology structure between a collection of UAVs is based on the algebraic graph theory. To handle the parametric uncertainty of the UAVs dynamics, a multivariable model reference adaptive control (MRAC) method is addressed to design the control law, which enables follower UAVs to track the leader UAV. The stability of the formation flight control system is proved by the Lyapunov theory. Simulation results show that the proposed distributed adaptive leader-following formation flight control system has stronger robustness and adaptivity than the fixed control system, as well as the existing adaptive control system.

Cycloidal rotors are a novel form of propulsion system that can be adapted to various forms of transport such as air and marine vehicles, with a geometrical design differing significantly from the conventional screw propeller. Research on cycloidal rotor design began in the early 1930s and has developed throughout the years to the point where such devices now operate as propulsion systems for various aerospace applications such as micro air vehicles, unmanned air vehicles and compound helicopters. The majority of research conducted on the cycloidal rotor’s aerodynamic performance have not assessed mitigating the dynamic stall effect, which can have a negative impact on the rotor performance when the blades operate in the rotor retreating side. A solution has been proposed to mitigate the dynamic stall effect through employment of active, compliant leading-edge morphing. A review of the current state of the art in this area is presented. A two-dimensional, implicit unsteady numerical analysis was conducted using the commercial computational fluid dynamics software package STAR CCM+, on a two-bladed cycloidal rotor. An overset mesh technique, otherwise known as a chimera mesh, was used to apply complex transient motions to the simulations. Active, compliant leading-edge morphing is applied to an oscillating NACA 0015 aerofoil to attempt to mitigate the dynamic stall whilst maintaining the positive dynamic lift coefficient (Cl) contributions. It was verified that by applying a pulsed input leading-edge rotational morphing schedule, the leading-edge vortex does not fully form and the large flow separation is prevented. Further work in this investigation will focus on coupling the active, leading-edge motion to the cycloidal rotor model with the aim to maximise aerodynamic performance.

A new trajectory tracking control approach for an under-actuated stratospheric airship is proposed. There is a two-level structure of the proposed controller. A low-level controller based on non-linear vectorial backstepping method, with the rigid-body dynamics expressed on vector form, stabilises the attitude and velocity of the airship, while a high-level controller performs guidance and trajectory tracking task in the three-dimensional (3D) space. Furthermore, a control allocation module based on the active set algorithm is incorporated into the low-level controller to optimise the practical control inputs under constraints of actuator saturation. The closed-loop trajectory tracking control plant is proved to be globally exponentially stable through the Lyapunov theory. Finally, simulations show that the vectorial backstepping trajectory tracking controller can achieve desired tracking performances even if the airship is affected by parametric uncertainties and exogenous disturbances.

The assimilation of discrete data points with model predictions can be used to achieve a reduction in the uncertainty of the model input parameters, which generate accurate predictions. The problem investigated here involves the prediction of limit-cycle oscillations using a High-Dimensional Harmonic Balance (HDHB) method. The efficiency of the HDHB method is exploited to enable calibration of structural input parameters using a Bayesian inference technique. Markov-chain Monte Carlo is employed to sample the posterior distributions. Parameter estimation is carried out on a pitch/plunge aerofoil and two Goland wing configurations. In all cases, significant refinement was achieved in the distribution of possible structural parameters allowing better predictions of their true deterministic values. Additionally, a comparison of two approaches to extract the true values from the posterior distributions is presented.

In space, structures encounter various severe environments, including severe thermal conditions. The signal level of the radio wave from the Large Deployable Reflector (LDR) mounted on the Engineering Test Satellite-VIII (ETS-VIII) was observed to change during an Earth eclipse. This phenomenon was assumed to be caused by the thermal deformation of the LDR. Therefore, in this study, a means to suppress the thermal deformation is proposed and demonstrated by focusing on the internal force generated at the springs used to deploy the antenna. According to the numerical results obtained from finite element analyses, the thermal deformations at all apices that support the reflectors were suppressed at a high correction rate by adjusting the coefficients of thermal expansion in the structural members and by controlling spring forces differently in four areas depending on the distances from the constraint point.

In this paper, a novel thrusting manoeuvre control scheme is proposed for a small spacecraft which is based only on the gimbaled thrust vector control (TVC) system. The spacecraft structure is composed of a body and a gimbaled thruster where common attitude control systems such as reaction control system (RCS) and spin stabilisation are not employed. A nonlinear two-body model is considered for the characterisation of the gimbaled-nozzle spacecraft where the gimbal actuator provides the only active control input. The spacecraft attitude is affected by a large exogenous disturbance torque which is generated by a thrust vector misalignment from the centre of mass (CM). To achieve some performance goals in the both transient and steady-state modes, a new control scheme is derived based on the combination of two linear and nonlinear controllers. The proposed method ensures the attitude and thrust vector stability during an impulsive orbital manoeuvre while eliminating and rejecting an exogenous disturbance torque. The numerical simulations illustrate the applicability of this method for using in a small spacecraft and its efficiency in sustained operation.

The semi-analytical prediction of pollutants emissions from gas turbines in the conceptual design phase is addressed in this paper. The necessity of this work arose from an urgent need for a comprehensive model that can quickly provide data in the conceptual design phase. Based on the available inputs data in the initial phases of the design process, a chemical reactor network (CRN) is defined to model the combustion with a detailed chemistry. In this way, three different chemical mechanisms are studied for Jet-A aviation fuel. Furthermore, the droplet evaporation for liquid fuel and the non-uniformity in fuel-air mixture are modelled. The results of a developed augmented modelling tool are compared with the pollutants data of two annular engine's combustors. The CRN results have good agreement with the actual engine test rig emissions output. In conclusion, the augmented CRN has shown to be efficient in predicting engine emissions with a very short executing time (few seconds) using a small CPU requirement such as a personal computer.