Upset Recovery and Fault-Tolerant Control Projects

Upset Recovery and Fault-Tolerant Control 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 includes 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. UAVs operate under dangerous environments and are at risk of obtaining physical damage or being destroyed. When a UAV experiences a malfunction, being a result of physical damage or harsh environment impacts, the UAV must have the ability to isolate the fault and try to recover from it if possible. This leads to a whole new research fi eld, UAV fault-tolerant control systems.

The ESL has demonstrated autonomous waypoint navigation, take-off and precision landing of small UAVs using different methods and control algorithms. The ESL have also done a number of research in fault-tolerant systems, both passive and active control for UAVs. Current fault-tolerant control projects within the ESL are listed below.

Current Projects

 

Fault Tolerant Control for a Fixed-Wing UAV with Partial Tail damage

Ryan Maggott

This project involves the research around investigating the effects of partial tail damage on a fixed wing UAV and implementing a control system to handle these changes. The aircraft will be modeled in order to determine the change in the aerodynamic coefficients. Trim values will need to be calculated to determine if stable flight is still possible. Stability analysis can be done on the damaged aircraft to show how the different modes might change. A control system will need to be implemented after the stability analysis to ensure that the aircraft is still capable of autonomous flight. The results and performance will be verified and tested in simulation and practical flight tests.

 

Autonomous Landing of a Fixed-wing Unmanned Aircraft with Partial Wing and Stabiliser losses

Gideon Hugo

This project involves the design, implementation and verification of an autonomous landing system for a fixed-wing unmanned aerial vehicle that is able to land the aircraft after suffering partial wing loss and partial losses of the horizontal and vertical stabilisers. The dynamic model for the damaged aircraft is based on an asymmetric, six-degrees-of-freedom equations of motion model. The effects of the partial wing and stabiliser losses on the aerodynamic coefficients, mass, centre of mass location, and moments of inertia are calculated as a function of percentage wing loss, percentage horizontal stabiliser loss, and percentage vertical stabiliser loss using vortex lattice techniques and computer assisted design software respectively. For the damage cases where a valid equilibrium exists, the nonlinear flight dynamics model is linearised about the equilibrium and the stability of the natural modes of motion are analysed as a function of percentage wing, horizontal stabiliser, and vertical stabiliser loss. A fault-tolerant flight control system is designed that ensures that the aircraft remain stable and within acceptable transient response specifications when the aircraft suffers partial wing, horizontal stabiliser, and vertical stabiliser losses. Autonomous landing is accomplished using a state machine that guides the aircraft through the landing phases. The system is verified using a high fidelity simulation environment and practical flight tests.