Bird-Inspired Gust Soaring for Unmanned Air Vehicles

点击翻译按钮获取中文摘要

The range and endurance of small unmanned aerial vehicles (SUAVs) is currently hindered by their limited battery capacity. Many SUAVs have a maximum flight time of up to ninety minutes, severely restricting their utility and preventing their benefits from being realised in fields such as disaster response, remote sensing (e.g. for agriculture and environmental monitoring) and reconnaissance. By performing particular manoeuvres to interact with local airflow appropriately, these vehicles can increase their potential or air-relative kinetic energy (the energy available to do useful work [1]), enabling them to fly further and for longer; this energy gain flight is known as 'soaring'. Updrafts of air form one condition for soaring flight (known as 'static soaring'); a bird can gain a 'free ride' to higher altitudes by flying in a thermal, for example, increasing its potential energy. Energy can also be extracted in nonuniform wind fields, where the wind direction and strength change in space and time, by utilising wind gradients - a technique known as 'gradient soaring'. Albatross are famous for exploiting this technique within the strong wind gradients above the ocean (in the atmospheric boundary layer) to achieve long-distance low-energy-expenditure travel. Automatic control systems for exploiting updrafts and large-scale gradients have received significant research, however these energy sources are not applicable for vehicles unable to deviate substantially from their desired flight path to exploit them, due for example to noise abatement procedures or a requirement to keep out of sight. Birds can be observed to gain energy en route through appropriate reactions to stochastic gradients - small-scale spatial gradients, caused for example by buildings, and gusts (gradients in time). This is known as 'gust soaring'. The goal of this research is to develop new gust soaring control algorithms for SUAVs in order to extend their range and endurance. The research will particularly focus on urban environments, where small-scale spatial gradients are common due to the complex interactions between the wind and structures.