Abstract
Gigacz R, Mohamed A, Poksawat P, Panta A and Watkins S. Exploring tandem wing UAS designs for operation in turbulent urban environments. International Journal of Micro Air Vehicles 2018; 10(3): 254-261. DOI: 10.1177/1756829318794167.
The authors would like to alert the readers to the following changes in their article:
The authors wish to clarify the relationship between this article and the following conference paper:
R. Gigacz, A. Mohamed, P. Poksawat, S. Watkins and A. Panta. 2017. ‘Developing a Stable Small UAS for Operation in Turbulent Urban Environments.’ International Micro Air Vehicle Conference and Flight Competition (IMAV) 2017. https://www.imavs.org/imav2017-proceedings/.
The journal paper should have referenced the conference paper article in the text and stated the relationship between them.
The error has been corrected by working with RMIT University to notify the publisher, Sage, of this error.
This error does not change the validity of the test or the results that were conducted. This was confirmed by the independent board who conducted this review.
The authors apologize to readers for this inadvertent error.
The changes are as follows:
An extra sentence is added to the Introduction section, where it clearly states the relationship between this journal paper and the conference proceeding.
An extra citation will be added as well. See the requested correction below:
Citation
The following citation is to be added.
Gigacz R, Mohamed A, Poksawat P, Watkins S, Panta A. Developing a Stable Small UAS for Operation in Turbulent Urban Environments. International Micro Air Vehicle Conference and Flight Competition (IMAV) 2017 [Internet]. 2017;184–9. Available from: http://www.imavs.org/papers/2017/198
Small unmanned air systems (SUASs) or micro air vehicles (MAVs) typically operate at low altitude, within the atmospheric boundary layer. This region is optimum for a range of SUAS applications in intelligence, surveillance, and reconnaissance (ISR) missions and is characterised as having high turbulence intensity.1,2 In the presence of wind, SUAS performance can degrade significantly.3 However, turbulence poses an even greater threat to the vehicle’s attitude stability.4–7 Consequently, attitude control in turbulence is a critical issue for SUASs and MAVs as identified by Mohamed et al.8 A range of passive and active methods have been explored to address this issue of poor attitude control in MAVs. Passive methods involve the aircraft’s natural ability to produce the aerodynamic forces to achieve stability, through design features of the aircraft (e.g. wing sweep, dihedral, etc.). Existing literature show that these techniques can only attenuate limited frequencies of perturbations.9 Active methods in contrast refers to the use of a control system, that goes through a sense (detect turbulence ahead of the aircraft), plan (consider desired control surface deflection ahead of time) and act (aerodynamic actuation) cycle, see Figure 1. It is near impossible to manually fly these aircraft in turbulence.10 Many MAVs require control input rates beyond the bandwidth of human operators.11 Employment of an active attitude control system is therefore vital as a micro-controller can provide higher input control rates than human pilots. Active turbulence mitigation techniques utilise MEMS sensors, electro-optical sensors and GPS sensors as feedback sensors. However, these conventional sensors were found to be challenged by severe perturbations from turbulence inputs.13 Active turbulence mitigation techniques have shown improved results when sensors with ability to detect the oncoming gusts are used.14,15 Phase-advanced multi-hole pressure-based sensors which are able to react to the turbulence ahead of the leading edge have been developed,16 and these have been shown to increase the stability of SUASs in turbulence.17 This paper explores passive and active methods of aiding the stability of SUASs through experimental wind tunnel testing of a tandem wing airframe, in conjunction with the phase-advanced multi-hole pressure probes, to further enhance the attitude control performance in high levels of turbulence. Roll perturbations were identified as the most significant disturbing factor for small fixed wing aircraft1,9 and consequently will be the focus of this paper
Small unmanned air systems (SUASs) or micro air vehicles (MAVs) typically operate at low altitude, within the atmospheric boundary layer. This region is optimum for a range of SUAS applications in intelligence, surveillance, and reconnaissance (ISR) missions and is characterised as having high turbulence intensity.1,2 In the presence of wind, SUAS performance can degrade significantly.3 However, turbulence poses an even greater threat to the vehicle’s attitude stability.4–7 Consequently, attitude control in turbulence is a critical issue for SUASs and MAVs as identified by Mohamed et al.8 A range of passive and active methods have been explored to address this issue of poor attitude control in MAVs. Passive methods involve the aircraft’s natural ability to produce the aerodynamic forces to achieve stability, through design features of the aircraft (e.g. wing sweep, dihedral, etc.). Existing literature show that these techniques can only attenuate limited frequencies of perturbations.9 Active methods in contrast refers to the use of a control system, that goes through a sense (detect turbulence ahead of the aircraft), plan (consider desired control surface deflection ahead of time) and act (aerodynamic actuation) cycle, see Figure 1. It is near impossible to manually fly these aircraft in turbulence.10 Many MAVs require control input rates beyond the bandwidth of human operators.11 Employment of an active attitude control system is therefore vital as a micro-controller can provide higher input control rates than human pilots. Active turbulence mitigation techniques utilise MEMS sensors, electro-optical sensors and GPS sensors as feedback sensors. However, these conventional sensors were found to be challenged by severe perturbations from turbulence inputs.13 Active turbulence mitigation techniques have shown improved results when sensors with ability to detect the oncoming gusts are used.14,15 Phase-advanced multi-hole pressure-based sensors which are able to react to the turbulence ahead of the leading edge have been developed,16 and these have been shown to increase the stability of SUASs in turbulence.17 This paper explores passive and active methods of aiding the stability of SUASs through experimental wind tunnel testing of a tandem wing airframe, in conjunction with the phase-advanced multi-hole pressure probes, to further enhance the attitude control performance in high levels of turbulence. Roll perturbations were identified as the most significant disturbing factor for small fixed wing aircraft1,9 and consequently will be the focus of this paper.