Owen McAree

Development of an autopilot system for rapid prototyping of high level control algorithms

This paper describes the development of a system for the rapid prototyping of high level control algorithms using an Arduino based commercial off the shelf autopilot called ArduPilot. It is capable of controlling multiple vehicle types, including fixed, and rotary wing aircraft as well as ground vehicles. The inner loop control is performed by ArduPilot, so the high level control can be rapidly prototyped and tested in Simulink, or an embedded system. The ability to conduct tests in software and hardware in the loop has also be developed, to enable safe testing of algorithms, which will speed up the development process. To show its functionality and ability to assist with the development process of algorithms, ArduPilot is used with a remote controlled aircraft in simulation and in real world testing to verify newly developed high level algorithms for UAVs.

Artificial Situation Awareness for Increased Autonomy of Unmanned Aerial Systems in the Terminal Area

Situation awareness is the human function of perceiving, comprehending and projecting the state of the environment which is of critical importance to the safe operation of aircraft. A highly autonomous Unmanned Aerial System (UAS) must replicate this behaviour in order to maintain an acceptable level of safety verses a manned vehicle. Nowhere in the flight is situation awareness more critical than during operation in the terminal area. Of primary concern during this stage of flight is the awareness of other traffic heading for the same airfield. This paper presents of a novel method of spatial projection of traffic vehicles encountered by an autonomous UAS in the terminal stage of flight. This projection method relies on a cooperative means of traffic perception, such as Automated Dependant Surveillance - Broadcast (ADS-B) and assumes there is a predefined route which vehicles follow through the terminal region. Whilst this is the case at the majority of airfield, traffic vehicles will not follow this path perfectly. This uncertainty in path following accuracy is captured by utilising a curvilinear reference frame and dealing with discrete transitions (such as the initiation of a turn) separately. It is shown that whilst this technique increases the computational complexity of the problem it can offer significant performance benefit.

A model based design framework for safety verification of a semi-autonomous inspection drone

In this paper, we present a model based design approach to the development of a semi-autonomous control system for an inspection drone. The system is tasked with maintaining a set distance from the target being inspected and a constant relative pose, allowing the operator to manoeuvre the drone around the target with ease. It is essential that the robustness of the autonomous behaviour be thoroughly verified prior to actual implementation, as this will involve the flight of a large multi-rotor drone in close proximity to a solid structure. By utilising the Robotic Operating System to communicate between the autonomous controller and the drone, the same Simulink model can be used for numerical coverage testing, high fidelity simulation, offboard execution and final executable deployment.

Development of a generic network enabled autonomous vehicle system

This paper describes the development of a system for autonomous vehicle testing, utilising conventional network infrastructure for communication and control; allowing simultaneous control of multiple vehicles of differing vehicle types. A basic level of autonomy is achieved through the use of an Arduino based commercial autopilot (ArduPilot), which also allows for remote vehicle control via MAVLink protocol commands given through serial communication. Traditionally messages are sent using point-to-point wireless serial modems. As these are restricted in terms of bandwidth and flexibility, an improved set-up is suggested, where an embedded computer system is attached to each vehicle. A custom written Node.js program (MAVNode) is then used to encode and decode MAVLink messages onboard allowing communication over a Local Area Network via Wi-Fi, A selection of hardware configurations are discussed, including the use of conventional Wi-Fi and long range Ubiquiti airMAX wireless routers. Both software and hardware in the loop testing is discussed, in addition to the ability to to perform control from Matlab/Simulink. With all the infrastructure in place, algorithms can be rapidly prototyped. As an example use of the system, a quad-rotor visually tracks a robot while using a remote Matlab installation for image processing and control.

Path following for small UAVs in the presence of wind disturbance

This paper presents an alternative approach of designing a guidance controller for a small Unmanned Aerial Vehicle (UAV) to achieve path following in the presence of wind disturbances. The wind effects acting on the UAV are estimated by a nonlinear disturbance observer. Then the wind information is incorporated into the nominal path following controller to formulate a composite controller so as to compensate wind influences. The globally asymptotic stability of the composite controller is illustrated through theoretical analysis and its performance is evaluated by various simulations including the software-in-the-loop. Initial flight tests using a small aircraft are carried out to demonstrate its actual performance.

ROBO-GUIDE: Towards Safe, Reliable, Trustworthy, and Natural Behaviours in Robotic Assistants

In this paper we describe a novel scenario, whereby an assistive robot is required to use a lift, and results from a preliminary investigation into floor determination using readily-available information. The aim being to create an assistive robot that can naturally integrate into existing infrastructure.

Floor determination in the operation of a lift by a mobile guide robot

Robotic assistants operating in multi-floor buildings are required to use lifts to transition between floors. To reduce the need for environments to be tailored to suit robots, and to make robot assistants more applicable, it is desirable that they should make use of existing navigational cues and interfaces designed for human users. In this paper, we examine the scenario whereby a guide robot uses a lift to transition between floors in a building. We describe an experiment into combining multiple data sources, available to a typical robot with simple sensors, to determine which floor of the building it is on. We show the robustness of this approach to realistic scenarios in a busy working environment.

Symbiotic relationship between robots — a ROS ARDrone/YouBot library

A Symbiotic relationship between robots is theoretically developed. It is characterised by sharing sensory information and tightly coordinating operational logic by taking care of each others needs during missions. The system is characterised by an intertwined reasoning system while having separate conditioning and execution of plans to achieve subgoals to support each other. The results are illustrated on strong operational inter-dependence of a rover and a drone through shared logical inference. The drone uses the rover as a landing pad and the rover uses the drone to complements its sensor system by information gathering. There is a GitHub library provided in association with the demonstration for generic use of adding cameras and cooperation logic to a AR. Drone 2.0 and a KUKA youBot system. The benefits of symbiotic relationship are quantitatively evaluated on the demonstration example.

Lateral control of vehicle platoons with on-board sensing and inter-vehicle communication

This paper presents a lateral control strategy for a platoon of vehicles which utilises only data which can realistically be measured by each vehicle, augmented with Inter-Vehicle Communication (IVC). The control problem resembles those which exist for longitudinal control and this introduces the challenge of estimating a vehicles lateral position and velocity when direct measurement is not possible (due to lane markings being obscured by a preceding vehicle). It is shown that the associated robust controller, which we propose, exhibits string stability in the presence of sensor and actuation delays and a high fidelity simulation is conducted to verify this.

Agent-based autonomous systems and abstraction engines: Theory meets practice

We report on experiences in the development of hybrid autonomous systems where high-level decisions are made by a rational agent. This rational agent interacts with other sub-systems via an abstraction engine. We describe three systems we have developed using the EASS BDI agent programming language and framework which supports this architecture. As a result of these experiences we recommend changes to the theoretical operational semantics that underpins the EASS framework and present a fourth implementation using the new semantics.