Browsing by Author "Engelbrecht, J. A. A."

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    Automated landing of an intelligent unmanned aerial vehicle in crosswind conditions using total energy control
    (2014-12-10) Le Roux, C. T.; Engelbrecht, J. A. A.
    ENGLISH ABSTRACT: This paper presents the development, implementation and verification of a flight control system for the automated landing of an intelligent unmanned aerial vehicle (UAV) in crosswind conditions. There is an increasing number of commercial opportunities for UAVs in business, agriculture, industry and mining, the emergency services and security services. The major barrier to commercialisation of UAVs is the certification process, where automated take-off and landing is a key feature required. The automated landing system presented in this paper uses a longitudinal control system based on the total energy control system (TECS), and a lateral control system that combines a heading and guidance controller with a cross-track error controller. A software state machine is used to advance the flight control system through the different stages of the automated landing. The TECS architecture allows the airspeed and flight path angle to be decoupled, while the Cross-Track Controller uses a limited integrator to drive the cross-track error to zero in the presence of crosswind. The automated landing system is implemented on a UAV with an on-board computer, sensors and actuators, and is verified in simulation and with practical flight tests. The hardware simulation results show that the UAV is able to land autonomously in crosswinds up to 3.6 metres per second, with a landing accuracy of 3.50 metre in-track and 0.12 metre cross-track.
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    A hardware-in-the-loop simulation facility for the attitude determination and control system of SUNSAT
    (Stellenbosch : Stellenbosch University, 1999-12) Engelbrecht, J. A. A.; Du Plessis, J. J.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical & Electronic Engineering.
    ENGLISH ABSTRACT: hardware-in-the-Ioop simulation facility was developed for the attitude determination and control system (ADCS) of the Stellenbosch University Satellite (SUNSAT), a low earth orbit, nadir pointing microsatellite. Software simulations were created to describe the orbital and attitude dynamics of the satellite, and also to describe the space environment, including the geomagnetic field, sun, earth horison and star field. Hardware emulators were designed to emulate the interfaces of the satellite's sensors and actuators with the ADCS tray. The simulation software and the hardware emulators were then combined to systematically close the hardware loop around the engineering model of SUNSAT's ADCS. A satellite-in-the-Ioop simulation mode was also included in the hardware-in-the-Ioop simulation facility so that whole orbit data collected and recorded by the SUNSAT flight model and transmitted to the ground station could be fed to simulations of the on-board ADCS algorithms. The satellite-in-the-Ioop simulation was used to investigate an unmodelled disturbance torque acting on the satellite body which' was revealed by the whole orbit data.
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    Proof of concept : large-scale monitor and control of household water heating in near real-time
    (Stellenbosch : Stellenbosch University, 2013-07) Booysen, Marthinus J.; Engelbrecht, J. A. A.; Molinaro, A.
    Two fundamental challenges for efficient energy management are the lack of timely demand and consumption information at the distribution level, and inability to responsively control supply at that level. With recent advances made in wireless communications and machine-to-machine (M2M) networking, a plethora of new solutions have been proposed for smart-grid and home automation. The many approaches, however, focus on the communications and technological domains of these solutions. In this paper we present the design and results of a proof-of-concept project, in which 18 homes were equipped to remotely monitor and control hot water cylinders in real time. The system makes use of the SMART platform to collect and collate telemetry data, and to deliver commands through the use of a cellular network. Users can set the on-off times of their water heating, and also monitor the consumption on a daily basis, in energy or monetary units. The data is centrally processed to provide useful information to the utility, such as the expected total demand for the system in 15 minute intervals, detected leaks, sudden drops in pressure, anode depletion, and to control each cylinder individually. In this paper we look at the system design and highlight some key results.