Cees Bil

Wing morphing control with shape memory alloy actuators

Aircraft morphing is referred to as the ability for an aircraft to change its geometry in flight. Formally, flaps, spoilers, and control devices are considered morphing, but in general, morphing in aerospace is associated with geometrical changes using smart materials such as shape memory alloys. Shape memory alloy is a material that changes shape under heating and produces force and deflections, which make it potential actuator for a wing morphing system. The motivation behind this study is the application to small-sized and medium-sized unmanned air vehicles and the potential to increase range or endurance for a given fuel load through improved lift-to-drag ratio. The camber line of an airfoil section, the predominant parameter affecting lift and drag, is changed by resistive heating of a shape memory alloy actuator and cooling in the surrounding air. Experiments were conducted under wind tunnel conditions to verify analysis and to investigate the effects of its application on the aerodynamic behavior of the wing. This study investigated three control methodologies: the conventional proportional–integral–derivative controller, proportional–integral–derivative with robust compensator, and proportional–integral–derivative with anti-windup compensator. The latter proved to have superior performance in achieving and maintaining a required level of morphing. In addition, the power required to the shape memory alloy actuators under aerodynamic load, and the effect of ambient temperature was also investigated.

An intelligent system for automatic layout routing in aerospace design

This paper discusses the development of an intelligent routing system for automating design of electrical wiring harnesses and pipes in aircraft. The system employs knowledge based engineering (KBE) methods and technologies for capturing and implementing rules and engineering knowledge relating to the routing process. The system reads a mesh of three dimensional structure and obstacles falling within a given search space and connects source and target terminals satisfying a knowledge base of design rules and best practices. Routed paths are output as computer aided design (CAD) readable geometry, and a finite element (FE) mesh consisting of geometry, routed paths and a knowledge layer providing detail of the rules and knowledge implemented in the process. Use of this intelligent routing system provides structure to the routing design process and has potential to deliver significant savings in time and cost.

Application of Smart Materials for Adaptive Airfoil Shape Control

The development of adaptive airfoil control can potentially improve flight performance by optimizing the maximum lift-to-drag ratio throughout all flight regimes. Improved flight performance translates into weight and fuel savings. Smart material is a suitable candidate for adaptive airfoil design as it can be activated to alter the shape of the airfoil. This paper presents an overview of smart material application for adaptive airfoil control with focus on shape memory alloy actuator and flexible skin for variable camber airfoil. This investigation is the first step in the development of an adaptive airfoil that is able to be utilized on an Uninhibited Aerial Vehicle. The influence of changing airfoil’s maximum camber on aerodynamic performance was also explored and the analysis is presented.

Investigation in wireless power transmission for UAV charging

This paper proposes application of wireless power transfer for charging of electric-powered Unmanned Air Vehicles (UAV)s. Multi-rotor systems, such as quadrotors, are light-weight and easy to operate. They are available in different sizes and with the wide range of capabilities. The main limitation of electric-powered UAVs is their range and endurance, due the limited battery capacity. Increasing battery system size is not a viable solution as its weight becomes a limiting factor. Supercapacitors are not an option, because of their low energy density. An alternative is to recharge UAV on the job, using wireless energy transfer (WET). WET was originally investigated by Nikola Tesla in the beginning of the 20th century. His patents are now common ground for any power transmission technology research, both wired and wireless. Investigations in resonance-based wireless energy transfer promise efficient wireless power transmission over several meters. This offers an ability to recharge moving vehicles, such as cars, trains and UAVs, wirelessly. For example, this technology can be applied to extend the range of UAVs used for the inspection of power transmission lines and towers. Presented project investigate capabilities and limitations of the wireless power transmission, for particular UAV application, i.e. for the infrastructure inspections.

Adaptable methodology for automation application development

The automation of engineering processes through Knowledge Based Engineering and Design Automation methods and technologies can provide significant savings in project scheduling and cost, increasing competitiveness in a changing aerospace market. In this paper we present outcomes of a research project aimed at improving engineering automation capability through development of a tool for automatic rule based path-finding for the complex engineering task of aircraft electrical harness and pipe routing.

Control design for unmanned aerial vehicle swarming

Abstract The collective behaviour observed in many social insects and animals provides the inspiration for the development of multi-vehicle control systems. The distributed nature of the multi-vehicle control problem enhances the performance of the collective system along the dimensions of scalability, robustness, and fault tolerance. The distributed/decentralized nature of the cooperative control task introduces many sub-problems often associated with network control design. In this paper, a survey of recent results in the field of cooperative control for multi-vehicle systems is presented. Various applications are discussed and presented in a mathematical framework to illustrate the major features of the cooperative control problem. Theoretical results for various cooperative control strategies are presented by topic and applied to the multi-vehicle applications.

Numerical Simulation of an Adaptive Airfoil System using SMA Actuators

Shape memory alloy (SMA) is lightweight, produces high force and large deflection which makes it a suitable candidate for actuator in the adaptive airfoil system design. The deflection of a variable cambered wing is controlled by means of resistive heating of SMA actuator and cooling in the surrounding air. An experimental wing model was developed using ABS to test the application of the SMA actuators. The SMA actuators were fixed underneath the wing skin. The heating of the wires caused them to contract, creating a force and generating a moment which deflects the wing. A wind tunnel test was performed to investigate the change in lift to drag ratio of the wing when the actuator is switched on and off. The results proved that the use of ABS skin and SMA actuators in the wing model is reliable as significant change in lift to drag ratio was detected when the wing was morphed.

Developing a rule engine for Automated Feature Recognition from CAD models

The detailed development phase in modern engineering project lifecycles is characterised by the iterative use of a number of engineering software tools. Inefficient integration between these tools often results in a high volume of manual data manipulation, for example the derivation of analysis and manufacturing models from detailed design models. The automatic recognition of engineering features from product geometry has potential to improve integration efficiency and reduce time and costs of downstream processes of Computer Aided Design (CAD) system based design. This paper introduces a methodology for developing and executing rules to identify engineering features from geometric data. The methodology has been implemented in an Automated Feature Recognition (AFR) system that identifies and extracts analysis features to feed stress analysis algorithms.

The Application of Fuzzy Logic on Transition Manoeuvre Control of a New Ducted-Fan VTOL UAV Configuration

The development of a fuzzy logic controller on a new configuration of ducted-fan VTOL UAV is presented for automating the transition manoeuvre. The design goal is to have a smooth push-over transition flight from low speed vertical flight to high speed horizontal flight in the presence of wind disturbance and without the need of using complicated control strategies. A target attitude for the transition is selected and then compared with the current vehicle attitude. This gives the attitude errors that are used to generate command signals to the vehicle controller. Simulation results demonstrate that the UAV was able to perform a smooth transition manoeuvre and has a good overall performance.

Fault tree analysis for composite structural damages

Composite airframes suffer from complex damage modes during operation. Many investigations tend to look into specific aspects of damage mechanisms but seldom take a systematic view. This paper introduces a new fault tree methodology to synthesize various damage modes of composite structures by identifying possible damage causes. Qualitative analysis is performed incorporating structure importance analysis, probability importance analysis and relative probability importance analysis. Quantitative analysis by Monte Carlo simulation is then conducted as a validation to demonstrate the feasibility of the fault tree for composite damages. A number of options addressing main damage causes are proposed to improve the reliability of composite structures. Engineers from airlines and manufacturers can use this method to prioritize the main damage causes in different situations as a failure preventative tool or damage evaluation. Also, this approach can be extended to provide valuable inputs to other advanced methodologies to perform better diagnosis and prognosis for composites.