Bio-inspired wing morphing for unmanned aerial vehicles using intelligent materials

摘要

Biologically inspired engineering or Bio-mimicry is the practice of developing designs and technologies inspired by nature. This conscious use of examples from nature is a form of applied case-based reasoning thus treating nature itself as a database of solutions that have survived for millions of years-survival of the fittest. Inspired by nature, we have developed aircraft wings that imitate the amazing flight of birds. This bio-inspired effort, which is the result of a collaborative research program with Defence Science Organisation National Laboratories of Singapore, is concerned with the design and development of a novel wing prototype for unmanned aerial vehicles (UAVs) that morphs seamlessly without the use of complex hydraulics and/or servo motors. The novel design, selected from a number of designs, is characterised by a high degree of flight adaptability, enhanced manoeuvrability and improved performance with a limited added weight. These characteristics were attained through the use of shape memory alloys as actuators in an antagonistic fashion. Unlike compliant actuators that require continued input of thermal energy, antagonistic setup does not suffer from this difficulty. This is because they require the thermal energy to deform the wing but not to maintain its morphed shape. Structural analysis based upon safety factors specified by FAR23 standards and aerodynamic analysis using FLUENT were conducted on the novel designs to validate their suitability as viable wings for UAVs. In addition, conditioning of the shape memory actuators was conducted using a specially designed circuitry that imposes the appropriate heating and cooling cycles at set periodic times. The outcome of this study is manifest in the new designs that satisfy the missions of different UAVs.