Autonomous Take-Off and Landing Projects
Autonomous Take-Off and Landing at the ESL
Unmanned Aerial Vehicles has become more popular among the military and for commercial uses and are used for various applications. Notable applications include Combat, Security, Search and Rescue, Monitoring, Disaster Management, Crop Management, Communications, and surveying. A UAV is adapted for a specific application in order to perform at it’s best for the given task. Each application introduces new uncertainties and complications that need to be considered in the development process. A fully autonomous UAV is capable of performing autonomous take-off, flight navigation and autonomous landing.
A number of work has been done within the ESL on unmanned aerial vehicles, these include autonomous take-off and landing of fixed-wing and rotor aircraft. Current projects within the ESL are listed below.
Autonomous aircraft landing under crosswind conditions
Andrew de Bruin
The main contribution of this project is the development of a robust control system with excellent disturbance rejection capabilities that will allow for accurate landing of a fixed-wing aircraft under crosswind conditions. Control system techniques that were implemented in previous projects at the ESL were not explicitly designed to land an aircraft under adverse atmospheric conditions; rather, landing tests were conducted during ideal or close-to-ideal wind conditions. This project will therefore focus on the development of robust controllers implemented in a way that exploits the advantages of various crosswind landing techniques.
Click here to view project video.
Configuration design and system modelling of a tethered multi-rotor aircraft
A System Engineering approach will be used to model a tethered multi-rotor aircraft. This study will include the following activities:
- Capturing and analysing the requirements for a tethered multi-rotor aircraft for application as an airborne surveillance platform for naval vessels.
- Converting the requirements into system specifications.
- Performing the configuration design of a system that will meet the specifications.
- Performing first-order design of the sub-systems of a suitable airborne system (first-order sizing, methods, interfaces, dynamics and effects and sub-system modelling).
- Simulated implementation of the design (by integrating the sub-system models into a suitable system simulation).
- Verification that the design meets the system specifications (by simulation).
- Validation that the design meets the system requirements (by simulation and argument).
Flight control for a tethered rotor vehicle
The objective of this research is to design and evaluate autonomous flight control algorithms for a tethered multi-rotor UAV. The concept of a tethered system aims to significantly extend the flight times of the payload-capable multi-rotor UAVs currently available, thereby broadening their boundaries of application. The flight control algorithms are to accommodate the influence of the tether on the stability of the aircraft, and make provision for the lengthening and shortening of the tether. This research builds on work previously conducted in the ESL on the SLADE projects.
Autonomous Landing of a tethered multi-rotor aircraft
The project focuses on the implementation of an autonomous landing system for a tethered quadrotor aircraft. Instrumented quadrotors have been used in sea-combat situations to detect observables like artillery, cruise missiles, motor bombs, rockets and UAV’s. To increase flight duration, a tether can be used to transmit power to the quadrotor. The ESL has since embarked on a series of projects to control tethered quadrotors. This project focusses on the design of control systems to control the quadrotor in the presence of tether and wind disturbances. An instrumented tether-winch system has been designed to control the tension of the tether during flight.
Autonomous Landing of an Unmanned Helicopter on a Moving Platform
The project focuses on the design of the control systems, algorithms and methods required to implement the functional autonomous landing of an unmanned helicopter (1.5m rotor diameter) on a translating, heaving platform, representative of a moving ship deck. The designed systems have been successfully implemented in software- and hardware-in-the-loop simulations and are in the process of being practically tested. A large amount of additional work has dealt with the implementation of a prediction system to isolate ideal landing times for helicopter operations at sea.
Click here to view project video.
Autonomous landing of a fixed-wing unmanned aerial vehicle on a moving platform
Cornelus Le Roux
The project aims to autonomously land a model fixed-wing aircraft onto a moving platform, such as a ship’s deck. Building on its predecessor, the focus will also be to keep the accuracy of the touchdown point within tight bounds. Furthermore, attempts are made to reduce the effect of winds acting on the aircraft, as well as using total energy control to expand the different controllers tested in the laboratory environment and evaluate its viability for autonomous landing.
The system is currently undergoing practical implementation and flight testing, with minor further developments scheduled for simulation and investigation. Future work on this aircraft includes improved cross-wind control and cross-wind landing solutions.