Aerospace and Autonomous Aerial Vehicles
Aerospace and Autonomous Aerial Vehicles
Micro/nano
Unmanned Aerial Vehicles have rapidly gained in popularity in recent years. However, there are still many limiting factors that prevent similar proliferation of Autonomous Aerial Vehicles, and their use in a broad variety of fields. The overarching objectives of this research program are to establish technologies to allow for autonomous flight, and to explore their applicability to commercial and industrial tasks. The fundamental research conducted at the RMRL includes the development and analysis of autonomous control methodologies, aerial vehicle design and characterisation, and investigations into manufacturing technologies for aerial vehicles.
The RMRL boasts experimental research facilities that incorporate laser interferometry-based sensing and measurement for the precise positioning of autonomous aerial vehicles, experimental apparatus and measurement equipment that enable the characterisation of aerial vehicles, and manufacturing facilities that include state-of-the-art robotic carbon-fiber placement and additive manufacturing technologies.
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Aerial vehicle design
All commercially available multirotor helicopters suffer from a single inherent limitation: it is impossible to control their attitude and position independently. This underactuation is a result of utilising fixed-position rotors that only allow thrust to be generated in the vertical direction. This limitation significantly restricts the application of multirotor helicopters, and increases the burden on task and path planning systems.
By revisiting the design of multirotor helicopters, an aerial vehicle has been developed within the RMRL that circumvents this limitation. This is achieved through the addition of thrust-vectoring rotor mounts to a four-rotor multirotor helicopter platform. Further, research has been undertaken to characterise the multirotor helicopter, and to develop and implement control methodologies suitable for such an aerial vehicle.
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Autonomous system parameter identification
One of the challenges inherent in the development of autonomous aerial vehicles, is the tuning of autopilot systems. Tuning procedures typically involve manually flying the aircraft as tuning parameters are varied. These procedures require skillful operators, extended development time, and pose risk to the aircraft. Alternatives to these procedures often require access to sophisticated equipment such as wind-tunnels and state-of-the-art dynamics modeling and analysis software. Further, many tuning procedures result in conservatively tuned autopilot systems, which limit the flight envelope of the aircraft to simplify the tuning process.
To address this shortcoming, the design and implementation of autonomous sytems capable of updating tuning parameters in-flight are actively being researched within the RMRL. This work includes investigations into hybrid attitude determination techniques, adaptive and intelligent control methodologies, and experimental characterisation of such methodologies. To date, an autopilot system capable of autonomous self-tuning for high-wing fixed-wing aircraft has been developed within the RMRL.
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High-precision positioning of autonomous aerial vehicles
Applications of autonomous aerial vehicles within the manufacturing industry are increasingly demanding high-levels of positioning accuracy. For applications within indoor environments, GPS-based localisation is unreliable and alternatives, such as camera-based localisation, are extremely costly. Therefore, to address the need for precise positioning in indoor environments, research has been undertaken within the RMRL to develop laser-interferometry-based localisation and positioning of autonomouos aerial vehicles. This research has culminated in the development of a research facility enabling closed-loop laser interferometry-based positioning of multirotor helicopters.
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Hybrid-rocket development
Hybrid rockets employ liquid oxidisers and solid fuel grains as their propulsion system. The primary advantage of hybrid rockets over solid/liquid-propellant rockets is that they offer greater controllability and are relatively safer during operation. At RMRL, our research is currently focusing on investigating the rocket propulsion system using paraffin wax and nitrogen, as well as the methodology of manufacture using automated fibre placement and also the control method of the rocket. The object of the research project is to develop a methodology that allow a miniature rocket to hover in mid-air using thrust vectoring.