15,280 research outputs found
Equilibrium transition study for a hybrid MAV
Wind tunnel testing was performed on a VTOL aircraft in order to characterize longitudinal flight behavior during an equilibrium transition between vertical and horizontal flight modes. Trim values for airspeed, pitch, motor speed and elevator position were determined. Data was collected by independently varying the trim parameters, and stability and control derivatives were identified as functions of the trim pitch angle. A linear fractional representation model was then proposed, along with several methods to improve longitudinal control of the aircraft
UltraSwarm: A Further Step Towards a Flock of Miniature Helicopters
We describe further progress towards the development of a
MAV (micro aerial vehicle) designed as an enabling tool to investigate aerial flocking. Our research focuses on the use of low cost off the shelf vehicles and sensors to enable fast prototyping and to reduce development costs. Details on the design of the embedded electronics and the
modification of the chosen toy helicopter are presented, and the technique used for state estimation is described. The fusion of inertial data through an unscented Kalman filter is used to estimate the helicopter’s state, and this forms the main input to the control system. Since no detailed dynamic model of the helicopter in use is available, a method is proposed for automated system identification, and for subsequent controller design based on artificial evolution. Preliminary results obtained with a dynamic simulator of a helicopter are reported, along with some encouraging results for tackling the problem of flocking
Tightly Coupled GNSS and Vision Navigation for Unmanned Air Vehicle Applications
This paper explores the unique benefits that can be obtained from a tight integration of a GNSS sensor and a forward-looking vision sensor. The motivation of this research is the belief that both GNSS and vision will be integral features of future UAV avionics architectures, GNSS for basic aircraft navigation and vision for obstacle-aircraft collision avoidance. The paper will show that utilising basic single-antenna GNSS measurements and observables, along with aircraft information derived from optical flow techniques creates unique synergies. Results of the accuracy of attitude estimates will be presented, based a comprehensive Matlab® Simulink® model which re-creates an optical flow stream based on the flight of an aircraft. This paper establishes the viability of this novel integrated GNSS/Vision approach for use as the complete UAV sensor package, or as a backup sensor for an inertial navigation system
On mathematical modelling of insect flight dynamics in the context of micro air vehicles
This paper discusses several aspects of mathematical modelling relevant to the flight
dynamics of insect flight in the context of insect-like flapping wing micro air vehicles (MAVs).
MAVs are defined as flying vehicles ca six inch in size (hand-held) and are developed to
reconnoitre in confined spaces (inside buildings, tunnels etc). This requires power-efficient,
highly-manoeuvrable, low-speed flight with stable hover. All of these attributes are present in
insect flight and hence the focus of reproducing the functionality of insect flight by engineering
means. This can only be achieved if qualitative insight is accompanied by appropriate
quantitative analysis, especially in the context of flight dynamics, as flight dynamics underpin
the desirable manoeuvrability.
We consider two aspects of mathematical modelling for insect flight dynamics.
The first one is theoretical (computational), as opposed to empirical, generation of the
aerodynamic data required for the six-degrees-of-freedom equations of motion. For these
purposes we first explain insect wing kinematics and the salient features of the corresponding
flow. In this context, we show that aerodynamic modelling is a feasible option for certain flight
regimes, focussing on a successful example of modelling hover. Such modelling progresses
from first principles of fluid mechanics, but relies on simplifications justified by the known
flow phenomenology and/or geometric and kinematic symmetries. In particular, this is relevant
to six types of fundamental manoeuvres, which we define as those steady flight conditions for
which only one component of both the translational and rotational body velocities is non-zero
(and constant).
The second aspect of mathematical modelling for insect flight dynamics addressed here
deals with the periodic character of the aerodynamic force and moment production. This
leads to consideration of the types of solutions of nonlinear equations forced by nonlinear
oscillations. In particular, the existence of non-periodic solutions of equations of motion is of
practical interest, since this allows steady recitilinear flight.
Progress in both aspects of mathematical modelling for insect flight will require further
advances in aerodynamics of insect-like flapping. Improved aerodynamic modelling and
computational fluid dynamics (CFD) calculations are required. These theoretical advances
must be accompanied by further flow visualisation and measurement to validate both the
aerodynamic modelling and CFD predictions
Neuromimetic Robots inspired by Insect Vision
International audienceEquipped with a less-than-one-milligram brain, insects fly autonomously in complex environments without resorting to any Radars, Ladars, Sonars or GPS. The knowledge gained during the last decades on insects' sensory-motor abilities and the neuronal substrates involved provides us with a rich source of inspiration for designing tomorrow's self-guided vehicles and micro-vehicles, which are to cope with unforeseen events on the ground, in the air, under water or in space. Insects have been in the business of sensory-motor integration for several 100 millions years and can therefore teach us useful tricks for designing agile autonomous vehicles at various scales. Constructing a "biorobot" first requires exactly formulating the signal processing principles at work in the animal. It gives us, in return, a unique opportunity of checking the soundness and robustness of those principles by bringing them face to face with the real physical world. Here we describe some of the visually-guided terrestrial and aerial robots we have developed on the basis of our biological findings. These robots (Robot Fly, SCANIA, FANIA, OSCAR, OCTAVE and LORA) all react to the optic flow (i.e., the angular speed of the retinal image). Optic flow is sensed onboard the robots by miniature vision sensors called Elementary Motion Detectors (EMDs). The principle of these electro-optical velocity sensors was derived from optical/electrophysiological studies where we recorded the responses of single neurons to optical microstimulation of single photoreceptor cells in a model visual system: the fly's compound eye. Optic flow based sensors rely solely on contrast provided by reflected (or scattered) sunlight from any kind of celestial bodies in a given spectral range. These nonemissive, powerlean sensors offer potential applications to manned or unmanned aircraft. Applications can also be envisaged to spacecraft, from robotic landers and rovers to asteroid explorers or space station dockers, with interesting prospects as regards reduction in weight and consumption
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