Autonomous landing of a helicopter at sea: advanced control in adverse conditions (AC2)

The increasing use of unmanned aerial vehicles (UAVs) has spanned from the military domain to a wide range of civilian applications in recent years. Among many different types of UAVs, helicopters (or rotorcraft in general) have dominated in many applications because of their unique capabilities of hovering, low speed cruise and vertical take-off and landing (VTOL). Example applications can be easily found in aerial photography, film making and infrastructure inspection. However, unlike their full size counterparts, only few examples of using unmanned helicopters in maritime environments can be found, although the potential benefits of the rapid deployment, cost reduction and mission flexibility are great. The main challenge here is to land an unmanned helicopter accurately and safely on the deck of a ship, which needs to be conducted in an adverse maritime environment, such as external disturbances, ship movement and confined operational space.

This project aims to tackle this challenge by developing an integrated control framework for systems operated in adverse environments. It not only relies on traditional feedback mechanisms based on control errors, but is also able to anticipate environmental influences on the system dynamics and rectify them proactively. Specifically, by consolidating two powerful control concepts (i.e. disturbance observer based control and model predictive control) and further expanding their capabilities, the developed control framework will be able to deal with the complicated helicopter dynamics and to take into account the external disturbances from different sources, so as to improve the control accuracy and robustness. The development of this integrated control framework will be complemented by rigorous theoretical analysis and validated by realistic flight tests under adverse conditions.

In the light of the recent government promotion of maritime autonomous systems, the proposed research to enable autonomous landing of a helicopter on the deck of a ship would bring the advantages of unmanned helicopters into a vast range of applications in the maritime environment. This will complement surface and undersea maritime vehicles to form a truly 3-D autonomous capability at sea. Tasks such as environment monitoring, surveillance of vessel traffic and migrant flows, and cargo supply can be more efficiently performed by unmanned helicopters with modest cost. Allowing them to operate in adverse weather conditions will significantly improve their reliability and reduce the risks in the maritime environment. The proposed control framework will also play a critical role in fully exploring helicopters' VTOL capability in those tasks, for example to deliver humanitarian aid to boats with refugees and acquire samples from chemical or oil spills at sea, where precise manoeuvres are required.

Moreover, it is envisaged that the proposed control strategy can be used as a control synthesis tool not only for other types of small/micro UAVs in adverse conditions, but also in other application domains like autonomous surface vehicles, where disturbance impacts on system dynamics are also significant.

The proposed project aims to tackle the challenges in autonomous landing of a helicopter on the deck of a ship from an autonomous control perspective. Specifically, an integrated control framework for systems operated in adverse conditions will be developed, which will not only use traditional feedback mechanisms, but also be able to estimate and anticipate environmental influences on the system and compensate them proactively.

The research on fundamental control technology in this project will make significant impact on academic communities through the knowledge it created. This project is able to provide a new control synthesis tool for small unmanned aerial vehicles (UAVs), which are often operated in the adverse environment, to improve their flight stability and performance. We also believe the methods developed in this project will have wider applications in different domains (e.g. robotics, autonomous maritime vessels and general industrial control applications). The potential applications of autonomous vehicles in adverse environment enabled by the developed technique will have far reaching impact on economics and society.

The proposed project falls in the scope of Robotics and Autonomous Systems (RAS), which has been recognised as the one of "eight great technologies" by UK government for future growth. Among different types of robotics and autonomous systems, UAVs have already been used in a variety of applications, including in precision agriculture, environment monitoring and oil and gas exploration. Recently, in the light of the success of RAS in other sectors, UK government has made £9M funding available for autonomous maritime systems. Allowing autonomous helicopter landing on a ship deck will bring the versatility of autonomous helicopters into a vast area of maritime operations (e.g. environment monitoring, surveillance on vessel traffic and migrant flows, and cargo supply including medicine delivery). This will complement surface and undersea maritime vehicles to form a truly 3-D autonomous capability at sea. Therefore, this work will help UK to maintain the excellence in RAS across a wide range of application areas.

It has been estimated that the economic impact of UAV industry can reach astonishingly $82 (£56) billions between 2015 and 2025. This can be reflected that in addition to many small/medium aerospace companies working in this area, even Google and Amazon are developing drone delivery systems for small parcels. The outcomes of the this project will directly improve the flight performance and safety of such small UAVs in adverse weather conditions, which are not only important to tasks such as search and rescue, environment monitoring after disaster and precise delivery of emergency medicine, but will also improve the safety measures in integrating UAVs into national airspaces. Moreover, the expected outcomes will further extend the commercial potentials of small UAVs by allowing more flexible and safer landing procedures on moving vehicles or in proximity to structures. The industrial partners Roke Manor Research and Dstl have already shown great interests in this project.

The project outcomes will also have impact on educating the next generation of engineers. The PI is currently designing two new modules (Autonomous Vehicles and Rotorcraft Systems) for undergraduate/master students in the host department. The research outcomes will be embedded into teaching materials so as to let the student get insights on the cutting edge technologies in these areas.

We will maximize the project impact by sharing the research outcomes with academic communities, by closely collaborating with industrial partners, and by disseminating knowledge from the project to the general public through outreach activities.