A neuro-fuzzy controller method for smart material actuator (SMA) hysteresis modelling is presented, conceived for a morphing wing application. The controller correlates each set of forces and electrical currents that are applied to the smart material actuators with the actuator elongation. The actuator is experimentally tested for four forces, using a variable electrical current. The final controller is obtained through the Matlab/Simulink integration of three independent neuro-fuzzy controllers, designed for the increase and decrease of electrical current, and for null electrical current in the cooling phase of the actuator. This final controller gives a very small error with respect to the experimental values.

This paper presents the results of experimental and computational investigations on the effect of slot cavities on a supersonic projectile. Experimental work was carried out to show the effects of the slots on the drag at Mach numbers M = 1·36, 1·65, 1·83. The computational analysis was done at M = 1·36. A single configuration of the slot pattern was used with two different slot widths (0·5mm and 2·0mm). Flow features were investigated in the slotted area and at the base. The analysis presented includes the pressure distribution, the supersonic cavity flow and the effect of the slots on the overall aerodynamic drag. Unlike the case of slots at transonic speeds, the suction and blowing mechanism is not found at supersonic Mach numbers. Streamwise cavity slots cause a small base drag reduction. The reduction in total drag is modest when the width is 0·5mm. However, the experiments showed that with the wider slots (2mm) the drag actually increases at Mach numbers from 1·36 to 1·83.

Research studies have indicated that the optical flow parameter, time to close tau, is the basis of purposeful control in the animal world, and used by both fixed wing and helicopter pilots during manoeuvring. This parameter is defined as the instantaneous time to close a gap (spatial or force) at the current closing rate. A novel automatic flight control strategy has been developed that makes use of optical flow theory and in particular, the parameter tau. This strategy has been applied to two distinct problems; (1) the landing of a helicopter on a ship and (2) the lateral repositioning of a helicopter. The first is a challenging case because the landing of a helicopter on a ship is one of the most dangerous of all helicopter flight operations. Furthermore, helicopters are often subject to torque oscillations during rapid collective control, which increases pilot workload significantly when operating with low power margins and/or whilst performing tasks that require accurate heave control. The second case demonstrates the generality of the technique. Both automatic manoeuvres were simulated successfully within desired limits, with the novel control strategy creating a ‘natural’, smooth, tau motion.

This paper investigates a novel method for the control of aircraft. The concept consists of articulated split wing-tips, independently actuated and mounted on a baseline flying wing. The general philosophy behind the concept was that adequate control of a flying wing about its three axes could be obtained through local modifications of the dihedral angle at the wing-tips, thus providing an alternative to conventional control effectors such as elevons and drag rudders. Preliminary computations with a vortex lattice model and subsequent wind tunnel tests and Navier-Stokes computations demonstrate the viability of the concept for co-ordinated turns, with individual and/or combined wing-tip deflections producing multi-axis, coupled control moments. The multi-axis nature of the generated moments tends to over-actuate the flight control system, leading to some redundancy, which could be exploited to optimise secondary objective functions such as drag or bending moment.

Ultrasonic guided wave techniques have great potential for structural health monitoring applications. Appropriate mode and frequency selection is the basis for achieving optimised damage monitoring performance. In this paper, several important guided wave mode attributes are introduced in addition to the commonly used phase velocity and group velocity dispersion curves while using the general corrosion problem as an example. We first derive a simple and generic wave excitability function based on the theory of normal mode expansion and the reciprocity theorem. A sensitivity dispersion curve is formulated based on the group velocity dispersion curve. Both excitability and sensitivity dispersion curves are verified with finite element simulations. Finally, a goodness dispersion curve concept is introduced to evaluate the tradeoffs between multiple mode selection objectives based on the wave velocity, excitability and sensitivity.