Laser satellite communication effectively addresses high data rates, low latency, high security and license-free operation of down to Earth and inter-satellite data links, crucial for the growing data demands in space amid radio frequency spectrum congestion. However, this approach presents challenges, notably in meeting micro-radian pointing accuracy of laser beams due to the low divergence nature of the high frequency optical wavelengths utilised. Laser communication terminals handle the strict pointing accuracy requirements by segmenting the pointing strategies into coarse and fine pointing mechanisms. The coarse pointing assembly (CPA), the focus of this research, provides large field of view, low bandwidth laser beam pointing with minimal static and dynamic pointing error. Common pointing budgets allocate errors up to 100-500 μrad for static pointing and 1-5 μrad for dynamic pointing biases during operation. The CPA operates on the simultaneous actuation of two axes, elevation and azimuth, to anticipate relative spacecraft motion for inter-satellite links and alternatively, to Earth based ground stations. For complete closed loop pointing of the CPA, the elevation axes power, motor control signals and sensor feedback needs to pass over the rotating azimuth axis. The state of the art mechanisms used to accomplish this are flex wraps, flexible PCBs coiled around a central axis, which unspools and retracts for azimuthal movements. However, flex wraps negatively impact CPA pointing performance through their material stiffness destabilisation torques, limit the CPA lifetime due to material fatigue characteristics, pose manufacturing and assembly complexity, inhibit fully continuous 360 degree pointing operation of the CPA, and restrict the instruments achievable slew rates. The development in this domain of CPA technology has remained largely stagnant for multiple years.

This research looks into the field of contactless technology to analyse, design and develop a novel wireless interface for the continuous rotation, low torque and high precision pointing of CPAs, by aiming to eliminate all wired connections between the rotation axes. The conceptual design, analysis implementation and manufacturing of a contactless interface concept was carried out through a 10 month period, bringing the technology from TRL 1 to TRL 4, concluding with the testing and demonstration of a fully synchronous wireless power and bi-directional data transmission interface for CPA applications. The system accomplished a DC-DC raw power transfer efficiency of 73% and a maximum full duplex symbol rate over the contactless link of 100 kbps. Therefore, the contactless CPA interface displays the ability for a miniaturised and fully integrated solution to wirelessly couple power over free space while simultaneously enabling data transfer over a single coil element independent of any rotation effects.

The test results of the manufactured contactless interface displayed promise for the future implementation in a CPA, the system enables the full, undisturbed, continuous rotation of the CPA during operation. Complete pointing performance testing was not performed, however it is hypothesised that the implementation of the system would eliminate line resistance and material stiffness hysteric effects, conceivably removing all flex wrap induced pointing destabilisations and providing zero wear operations, removing instrument lifetime restrictions. However In doing so, the power transfer efficiency and number of signal data lines suffer a reduction as compared to flex wraps. As a part of this research, space radiation and thermal effects were not assessed in detail, however their influence was found to impact the overall design direction and component choices. ... Read more

The drone market has been steadily growing over the last decades, resulting in drones becoming more and more common 1. For the majority of the time, the drones provide valuable services, from inspection work and deliveries to applications in emergencies, such as search and rescue, or rapid deliveries of medical supplies. Unfortunately, because drones are available to everyone, misuse cannot be fully prevented. They can cause significant disruptions to aviation, violate privacy, or transport illegal substances, leading to financial losses, or more serious consequences. A notable incident, that caused the delay of close to 1,000 flights affecting approximately 140,000 passengers, took place in 2018 at London Gatwick Airport, where 2 drones caused the airport to shut down for over 24 hours [1]. Additionally, it has been reported by Dubai International Airport, that the estimated costs of halting airport operations due to drones resulted in losses of close to $100,000 per minute of downtime2. To counteract these hazardous situations, current anti-drone methods on the market include drone guns, quadcopters using catching systems, and radio frequency jamming systems. However, all of these methods come with their disadvantages. They either involve human interaction, have high operational costs, or cannot intercept quickly over a large area, leaving a large gap in the market for an efficient anti-drone system. The Air-Guard drone introduced in this report aims to fill this market gap, by providing a quick response time to a threat, while not compromising on neutralizing capabilities. It is a fixed-wing drone capable of autonomous visual tracking and catching unlicensed drones via a shooting net mechanism integrated with a parachute. Compared to multi-rotor drones, the Air-Guard drone concept has a longer range and higher efficiency, allowing it to be readily in the air until an unlicensed drone is detected. This is achieved thanks to its unique design inspired by bird morphology. Birds can actively morph their wings and tail surfaces to actively alter their aspect ratio, wing loading, and stability to achieve the most efficient flight configuration over a wide variety of flight profiles. Similarly, the Air-Guard drone morphs its wing and tail such that the drone can be stable while loitering, to then transition into high-g maneuvers in under a second. This allows the drone to more closely follow unlicensed drones in restricted areas and immobilize these drones in a matter of minutes autonomously. The morphing concept of the drone uses multiple actuators and elastic tendons in combination with specially designed artificial feathers to emulate bird morphology. The design also considers previously neglected areas of bird wing anatomy and incorporates bioinspired aerodynamic surfaces to delay stall and increase the maneuverability of the drone. This report is a follow-up of the midterm report, where the general configuration of the drone was set up. It aims to describe the progress on the Air-Guard project, mostly from a technical point of view, but also economic and operational aspects are covered. The UAV design is multidisciplinary and is influenced by many disciplines related to aerospace engineering. Aerodynamics, performance, structures, stability, control, and electronics considerations were combined to make the design possible. It was an iterative process, requiring careful coordination and communication between all the different departments. The result of this work translates into the design of a dual engine, 3.5 kg drone that is capable of loitering for an hour, with a maximum speed of 48 m/s. The wing span in extended configuration is 1.34 m, with a total length of 1.05 m. To neutralize the threat, the Air-Guard chases the unlicensed drone with the help of its high maneuver ability, then fires a net equipped with a parachute from the nose to capture it. The materials used are balsa wood for the fuselage and fixed-wing, while the morphing surfaces are made of aluminum and 3D-printable Celanese VECTRA A950LCP. A great emphasis was put on the sustainability aspect of the drone, which lead to an electrically powered UAV, having a structure that is 99% recyclable. ... Read more