Technical Field

[0001] The present disclosure relates to propulsion system design, various airframe configurations, navigation and guidance implementation, and sensing platform integrations of a new class of aerodynes.

Brief Description of the Drawings

[0002] FIG. 1 illustrates the first version of the propulsion system and its design parameterization.

[0003] FIG. 2 illustrates the second version of the propulsion system and its design parameterization.

[0004] FIG. 3 illustrates an aerodyne airframe with dimpled surfaces.

[0005] FIG. 4 depicts the outlet velocity, orientation of dimple rows and inwardly inclined airfoil scheme.

[0006] FIG. 5 is an illustration of aerodyne T4S airframe configuration.

[0007] FIG. 6 is an illustration of aerodyne 4S02 airframe configuration.

[0008] FIG. 7 is an illustration of aerodyne 4S01 airframe configuration.

[0009] FIG. 8 is an illustration of aerodyne CXT8S airframe configuration.

[0010] FIG. 9 is an illustration of aerodyne CX8S02 airframe configuration.

[0011] FIG. 10 is an illustration of aerodyne CX8S01 airframe configuration.

[0012] FIG. 11 is an illustration of aerodyne T6S airframe configuration.

[0013] FIG. 12 is an illustration of aerodyne 6S02 airframe configuration.

[0014] FIG. 13 is an illustration of aerodyne 6S01 airframe configuration.

[0015] FIG. 14 is an illustration of aerodyne CXT 12S airframe configuration.

[0016] FIG. 15 is an illustration of aerodyne CX12S02 airframe configuration.

[0017] FIG. 16 is an illustration of aerodyne CX12S01 airframe configuration.

[0018] FIG. 17 illustrates the naming convention of n-saucer aerodynes.

[0019] FIG. 18 depicts an example of photovoltaic TFSC design applied to aerodyne

T4S airframe.

[0020] FIG. 19 is a block diagram of the Geo-referential Odometry trajectory generation, navigation and guidance. [0021] FIG. 20 is an illustration of the position estimation and trajectory matching process.

[0022] FIG. 21 illustrates the UAV-GPiR (Ground-Penetrating Imaging Radar) application pertaining the internal evaluation of critical structures.

[0023] FIG. 22 illustrates the UAV-GPiR application pertaining the detection of deeply buried settlements.

[0024] FIG. 23 illustrates the UAV-GPiR application pertaining the detection of UXO, mines and other shallow to medium depth buried targets.

[0025] FIG. 24 illustrates the UAV-GPiR application pertaining the search and rescue on disaster or attacked sites.

[0026] FIG. 25 illustrates the UAV-GPiR application pertaining the evaluation of serviceability, safety and structural security of critical buildings and their sites.

[0027] FIG. 26 is an illustration of an airframe design of the autonomous personal aerodyne.

[0028] FIG. 27 is an illustration of an alternative airframe design of the autonomous personal aerodyne.

Detailed Description of Preferred Embodiments

[0029] A detailed description of systems and methods consistent with embodiments of the present disclosure is provided below. While several embodiments are described, it should be understood that the disclosure is not limited to any one embodiment, but instead

encompasses numerous alternatives, modifications, and equivalents. In addition, while numerous specific details are set forth in the following description in order to provide a thorough understanding of the embodiments disclosed herein, some embodiments can be practiced without some or all of these details. Moreover, for the purpose of clarity, certain technical material that is known in the related art has not been described in detail in order to avoid unnecessarily obscuring the disclosure.

[0030] The Coanda Effect-based propulsion and lift systems emerged in the VTOL aircraft world as a synergy of two traditional methods widely used to create lift and thrust, i.e. the fixed-wing design combined with the upper propeller creating lift through an airstream adherent over convex outer surfaces.

[0031] The propulsion system disclosed here is quite dissimilar from previous Coanda

Effect-based UAV solutions and is expected to enable superior aerodynamic performance, stability and payload capacity. These are achieved by generating lift and maneuverability forces in a more effective manner. Additionally, it offers an airframe that is virtually invulnerable to obstacle or debris impact and is able to hold altitude without being damaged in hostile environments.

[0032] The foundation of the enhanced propulsion design disclosed here is the replacement of the traditional open, shaft driven propeller by an enclosed impeller, to enable the Coanda Effect, eliminate all of the mechanical disadvantages of an open rotor and to provide safe, quiet, responsive, FOD-resistant directional control. [0033] As schematically outlined in FIG. 1 and FIG. 2, the brushless motor (1) transfers its mechanical energy to the air through the ducted, rotating impeller (2). The air flows from the inlet (EYE) to the impeller center and out along its blades. The centrifugal force hereby increases the air velocity. In other words, the air is sucked into the impeller at the impeller EYE and flows through the impeller channels formed by the blades between the shroud and the hub. The vanes orientation drives the magnitude and direction of the discharged air velocity (FIG. 4). The air stream is pushed through the air amplifier (6), shaped as a circumferential slit between the fixed saucer airfoil (3) and the fixed shroud housing (4). Air speed is actually amplified as a result of Venturi Effect, which describes the increase of air velocity or flow rate due to the decrement of a passage cross-section area. Subsequently, Bernoulli's principle explains the increase in air speed that occurs simultaneously with a decrease in pressure. Furthermore, the air amplifier makes efficient use of Coanda Effect, which results in keeping the air jet attached to a NACA-profiled surface, when the air flow passes over the fixed saucer airfoil (3) to produce the Primary Lift. Finally, the air stream that is still stuck on the saucer airfoil follows the peripheral shape and is discharged quasi-vertically downward. In brief, the air is sucked, optimally‘packed’ and energized by the impeller, amplified by the circumferential slit and clung to airfoil, due to Coanda Effect, to generate the main lift.

[0034] The impeller’s ability to increase air velocity and create flow depends mainly on the air pathway through the impeller. Vanes geometry (influence of vane orientation illustrated in FIG. 4) and outlet width are also performance-determining factors. Two principal impeller types have been considered: i) a closed, radial, curved-vane impeller providing higher efficiency, and ii) a semi-axial, radial discharge, curved-vane impeller providing a trade-off between pressure rise and flow. Both impeller types represent enhanced solutions that are more effective in terms of air transfer (suction), energizing and discharge than traditional propellers. Moreover, they provide FOD hazard control and eliminate the turbulence-related disadvantages of a propeller. Due to its compact design, the closed, radial impeller is preferred on coaxial configurations (FIG. 8, 9, 10, 14, 15 and 16).

[0035] Alternatively, the propulsive saucer may be equipped with any impeller type, which provides an optimum balance between airflow rate and airspeed, when blowing the saucer airfoil, in order to enhance the Coanda Effect. The impeller design, type and material depend upon matching flow characteristics that will provide a superior aerodynamic

performance than the propellers that are conventionally used with the selected brushless motor.

[0036] The air amplifier (circumferential slit) (6) is optimized by fine-tuning the parameters p# (FIG. 1 and FIG. 2), i.e. the clearance between saucer airfoil (3) and shroud housing (4), and the diffusing angles of both (3) and (4) surfaces, in order to reduce the harmful potentiality.

[0037] The fixed saucer airfoil (3) is a NACA-profiled surface that receives the airstream created by impeller and amplified when entering the airfoil, where the Coanda Effect applies and stimulates the diffusion of more air. In the same time, the Coanda Effect speeds up the air over the airfoil, and thus lowers the air pressure next to it, which in turn generates more lift in this area, creating the Primary Lift forces. In addition to being NACA-profiled, the saucer airfoil is also optimized for a favorable L/D ratio. Its surface is dimpled similarly to golf balls (FIG. 3 and FIG. 4). The dimples act as artificial turbulators and Coanda Effect enhancers, creating turbulence next to the surface and creating two layers of air going over the dimpled surfaces. The top layer is going faster than the bottom layer, i.e., air clings to the surface, which creates more turbulence and reduces the drag. The local dimple-induced turbulence lowers the pressure on the adherent layer. This imbalance creates an additional upward force on the airfoil, i.e. the Secondary Lift. The dimples are oriented in rows along the design lines of the NACA profiles (generic dimple rows shown in FIG. 4), in the streamline direction of the outlet velocity (air V) vector (FIG. 4).

[0038] A Tertiary Lift is produced by the pressure imbalance caused at the impeller’s

EYE (FIG. 1 and FIG. 2), around the air suction area. Furthermore, a Quaternary Lift is induced by the downward air discharge at the peripheral circumference, downstream of TPCP (FIG. 1 and FIG. 2).

[0039] The propulsion airfoils may be inclined inwardly in order to improve aircraft’s balance and stability. For example, a 5.0° inclination angle from the horizontal plane would determine a slight loss of lift (of only 0.4%) but would create a lift forces concurrence (FIG. 4). This inclination (a in FIG. 4) may also facilitate aircraft’s seemingly possible water travel, by ensuring the concurrence of the horizontal vector components too.

[0040] Two distinct designs of the fixed saucer airfoil are considered. The first version of surface of revolution is obtained by revolving the upper NACA profile curve (situated between leading edge and trailing edge, FIG. 1) around the impeller axis of rotation. The second version of surface of revolution is achieved by revolving the complete NACA profile curve consisting of both upper and lower curves (FIG. 2).

[0041] Placing the saucer airfoil leading edge in the vicinity of air discharge and air amplifier imposed a set of design parameters (p# in FIG. 1 and FIG. 2), affecting the airflow characteristics and the aerodynamic performance. The geometric parameterization (p1 , p2, p3, p4 in FIG. 1 and p5, p6, p7, p8 in FIG. 2) is meant to optimize the design cycle iterations, including the workflow steps related to digital (CFD) simulation, additive manufacturing and thrust testing.

[0042] Regardless the version of the surface of revolution, the upper side of the saucer airfoil is a dimple-finished surface whose generatrix is a curve resulted from the NACA profile tangentially connected to a vertical air discharge profile (TPCP - tangential profile connection point - in FIG. 1 and FIG. 2), and whose dimples (7) act as artificial turbulators and Coanda Effect enhancers, being oriented along the generatrices (FIG. 3 and 4). The configuration resulted from the blend of NACA and air discharge profiles is meant to increase the streamline- directional cross-section of saucer airfoil, similarly to a flaps-deployed position maximizing the lift with a small increase in drag.

[0043] Several airframe configurations have been considered. The aerodynes disclosed here are designed and built on a variable number of propulsive saucers, typically from minimum 4S to maximum 12S (T4S and CX12S02 in FIG. 17).

[0044] The landing gear systems have been designed in three versions:

1) conical tube leg landing gear (12, and FIG. 7, 10, 13 and 16);

2) fixed claw landing gear (11 , and FIG. 6, 9, 12 and 15); and

3) toroidal inflatable chamber landing gear (10, and FIG. 5, 8, 11 and 14).

[0045] The toroidal inflatable chamber increases the buoyancy, functionality and/or mission autonomy; the toroidal landing gear aerodynes are designed to lift and carry a significant weight compared to their estimated energetic consumption and also have the ability to take off, alight and loiter on water. All aerodynes illustrated here, which are built on He chambers, have similar features and operational scope.

[0046] The fixed claw landing gear is derived from toroidal landing gear by removing the inflatable chamber.

[0047] The aerodynes are named according to the airframe components, as listed in

Table 1 and illustrated in FIG. 17.

[0048] Table 1 :

[0049] Various methods have been developed to handle the UAV navigation in a

GPS/communication-denied environment. Most implementations were using either Visual SLAM or Visual Odometry. However, in a real-time flight routine with SLAM-driven navigation, the computational effort imposes constraints and inherent difficulties related to processing time, computational power and memory footprint. In practice, the Visual SLAM needs more computational resources for building and maintaining a live map, and, within an equivalent iteration, its execution is slower than Visual Odometry’s.

[0050] The Geo-referential Odometry method disclosed here copes with the

computational effort constraints that are conventionally encountered in UAV navigation, and proposes an MSDF approach, where the Geo- referential Odometry spatial data are integrated with data provided by GPS (when available), IMU and Barometric Altitude sensors. The Geo- referential Odometry navigation reinforces the development of a fully autonomous, intelligent aerodyne, which is built on a superior propulsion system perfectly adapted to pre-loaded mission trajectories and scenarios.

[0051] The aerodyne is equipped with a customized flight control computer and a mission computer. The flight control computer is used to perform low-level feedback control and trajectory tracking, whereas the mission computer integrates the on-board camera with the Geo- referential Odometry system through MSDF, in order to achieve the high-level mission command and control. [0052] First, according to the mission plans, a query will be placed to the Ground Station

Computer as part of the pre-flight procedure, to obtain a set of geo-referenced map tiles, via Google Static maps API. The tiles are generated from Google Maps according to pre-planned trajectory values, and are stored corresponding to specific formats for further processing. In order to ensure effective deviation corrections, the mission’s geo-referenced map tiles will be complemented by the complete set of geo-referenced tiles of contiguous areas, covering the whole spatial envelope centered on the starting location and sized to the boundary limits defined by the aerodyne’s endurance.

[0053] The real-time images transmitted by the on-board cameras are received and processed to determine the current position by real-time image geo-referencing. Position is computed by applying Image-Tile Matching and Position Estimation algorithms within an open- loop 3D trajectory generator. The trajectory is computed in accordance with the mission planning, initially without considering the collision checking. A mechanism of local collision avoidance is implemented as an intermediate element between the mission path planning and the trajectory generator. The trajectory matches the mission path accurately, within a mathematical induction process, as shown in FIG. 20. The trajectory generator ensures a collision-free path from a start point to a destination point, following the geo-referenced tiles. If assumed that:

1) all positions (Po, Pi, ... , P _k -i) are consistent with trajectory; and

2) P _k -i => P _k , i.e. the position P _k is consistent with the trajectory too, being computed from P _k -i by fusing the spatial data provided by the on-board sensors (I MU/barometric), and corrected by T _k tile matching and geo-referencing of the on-board image taken at t _k ,

it can then be concluded that the generated trajectory is correct. The matching algorithms are typically based on greyscale conversion of both on-board images and pre-loaded tiles, and subsequent feature extraction and comparison, or cross-correlated edge extraction.

[0054] The on-board camera parameters (focal length, rotation and scale) are stored in the state vector S _k , and are used to compute the image projection matrix, i.e. the geometric transformation for image re-orientation. Then, P _k is estimated from P _k -i and S _k (including I MU/barometric data), and is corrected with TRV _k . Corrected P _k is also used to put forward the next tile (T _k+i ).

[0055] By taking advantage of the highly resilient propulsion system disclosed here, the

GPS/communication-denied navigation founded upon Geo-referential Odometry is not essentially dependent on IMU data. By satisfying the typical computational effort constraints and requirements, the Geo- referential Odometry navigation becomes a functional gap filler and backup to both GPS and inertial navigation systems, and can supplant either of them or both.

[0056] The block diagram of the Geo-referential Odometry navigation system is presented in FIG. 19.

[0057] The conventional propeller-driven UAVs cannot be supplied with solar power cells, for their airframes do not feature fixed airfoils or other airframe surfaces that would be large enough to be utilized as solar cell substrates. Contrariwise, the class of aerodynes listed in Table 1 and illustrated in FIG. 17 features an ideal airframe for a solar-electric UAV design. The integration of photovoltaic cells adapted to curved and/or flexible substrates affords key functional improvements comprising:

the maximization of solar power generation in contrast to the existing versions of conventional propeller-driven UAVs;

the successive layer design, wherein the solar cells are enclosed within the airframe

components, such as propulsive saucers and fuselage, by either transfer or attachment in between the rigid upper substrate and a clear, thin, dimple-finished cover (13, FIG. 18), which is attached to the rigid upper substrate and exposed to sunlight; and

improved safety, reliability and endurance.

[0058] Various custom photovoltaic designs involving both saucer airfoils and central body are being considered. The TFSCs are enclosed within the airframe components by either transfer or attachment in between the rigid substrate and a clear, thin, dimple-shaped (FIG. 3) cover, which is exposed to sunlight. This design is supported by several methods currently available for transfer printing of either the absorber materials or the entire TFSCs onto flexible or curved rigid substrates. These transfer printing methods, in comparison to the direct deposition of TFSCs on substrates, overcome the incompatibility issues between the thermal, mechanical and chemical properties of these substrates and the fabrication conditions.

[0059] The superior aerodynamic performance of propulsive saucers enabled the development of Autonomous Personal Air Vehicles (FIG. 26 and 27), which are built on several solar-electric design configurations (listed in Table 1) affording controllable urban flight. Their airframes include the toroidal inflatable chambers providing increased buoyancy and payload capacity.

[0060] The Geo-referential Odometry ensures a self-controlled optimal trajectory guidance and navigation between two selectable take-off/landing points within any safe flyable urban area. The operational air space is initially mapped, decomposed into and pre-installed as a set of contiguous tiles supplied by HD aerial imagery photo-scanning, similarly to Google map’s geo-referenced tiles, but of higher resolution and update frequency.

[0061] The application scope of the aerodynes documented here ranges from integrated subsurface and aboveground 3D-imaging of critical structures to detection of underground targets with a high level of danger and security risk, supporting both Military and Civil projects and programs. The aerodynes can be integrated into various UAV-GPiR systems making up a distinct product suite for executing several applications related to National Security and

Defence, comprising:

internal evaluation of critical structures (FIG. 21);

detection of deeply buried settlements (FIG. 22);

detection of UXO, mines and other shallow to medium depth buried targets (FIG. 23);

search and rescue on disaster or attacked sites (FIG. 24); and

evaluation of serviceability, safety and structural security of critical buildings and their sites (FIG. 25). [0062] The UAV-GPiR application pertaining the internal evaluation of critical structures consists of:

the deployment of a controllable cable-driven GPiR cart (14) on vertical and positively sloped surfaces;

a dynamically stable GPiR cart, which is cable-deployed below the propulsive saucers, where the turbulence-related disadvantages of conventional UAV propellers are eliminated; and the ability to obtain the internal deterioration index (15), via a non-intrusive UAV-GPiR scanning.

[0063] The UAV-GPiR application pertaining the detection of deeply buried settlements consists of:

a hybrid GPiR cart deployment system (16), wherein the GPiR antenna can be either fixed to airframe or cable-deployed/retracted for either airborne or ground-contact sensing;

the ability to operate autonomously over large remote or inaccessible areas in either individual or collaborative mode of navigation; and

the assignment of high-level mission command and control provided by the Geo-referential Odometry navigation.

[0064] The UAV-GPiR application pertaining the detection of UXO, mines and other shallow to medium depth buried targets consists of:

the integration of a UAV-GPiR medium frequency system supporting a fixed or

deployable/retractable GPiR antenna (17) for either airborne or ground-contact sensing;

the ability of scanning large areas through a collaborative mode of operation; and

the assignment of high-level mission command and control for an enhanced autonomous behaviour, provided by the Geo-referential Odometry.

[0065] The UAV-GPiR application pertaining the search and rescue on disaster or attacked sites consists of:

the integration of a UAV-GPiR medium frequency system supporting a fixed or

deployable/retractable GPiR antenna (17) for either airborne or ground-contact sensing;

the ability of scanning large areas through a collaborative mode of operation; and

the assignment of high-level mission command and control for an enhanced autonomous behaviour, provided by the Geo-referential Odometry.

[0066] The UAV-GPiR application pertaining the evaluation of serviceability, safety and structural security of critical buildings and their sites consists of:

a hybrid GPiR cart deployment system (20), wherein the fixed GPiR antenna can be cable- deployed/retracted for either airborne or ground-contact sensing;

providing the ability to operate autonomously over large building sites in either individual or collaborative mode of navigation; and providing the spatial qualitative and quantitative data that is used to build an accurate stratigraphic-based hydrogeological model (21), complemented with the exact topography of the extended building/structure site and the internal structural deterioration mapping.