Unmanned aerial vehicle with ground mobility

Abstract

The invention is an unmanned aerial vehicle (UAV) with ground mobility, comprising motor-driven first and second grid wheel structures (17, 19) rotatably attached to a base structure (10). Each of the first and second grid wheel structures (17, 19) at least partly surrounds at least one rotor (12) of the UAV. The UAV has an upright ground position in which a centre of gravity of the UAV is below the axis of rotation. The first and second grid wheel structures (17, 19) have the same largest radius which extends beyond other parts of the UAV which are at a lower height than an axis of rotation in said upright ground position. The first and second grid wheel structures (17, 19) are arranged with a spacing from each other along said axis of rotation, and an image capturing device (14) is arranged in a centered position with respect to said spacing.

Description

[0001] UNMANNED AERIAL VEHICLE WITH GROUND MOBILITY

[0002] TECHNICAL FIELD

[0003] The invention relates to an unmanned aerial vehicle (UAV) with ground mobility, more particularly to an autonomous, semi-autonomous or remotely controlled vehicle capable of both aerial and ground / terrestrial locomotion.

[0004] BACKGROUND ART

[0005] The ability to quickly reach a target location without needing to navigate obstacles or challenging terrain makes aerial vehicles an excellent choice in applications like search and rescue or military surveillance. UAVs, such as drones may be utilized for such purposes, for example for carrying out observation tasks by means of onboard sensors. The acquired data may be transmitted to a central station. This known flying devices can have different configurations based on the number of rotors used. Single rotor, coaxial rotors, tandem rotors, tricopter, quadcopter, hexacopter, and octocopter are all different types of rotorcrafts. UAVs are usually powered by an onboard battery which is required to supply power for both propulsion, onboard sensors and other electronics. However, it is difficult for UAVs to remain airborne for an extended period of time because of their high energy consumption.

[0006] There are known solutions to combine both aerial and ground locomotion possibilities in a vehicle. These vehicles, for example UAVs, combine the characteristics of drones with those of land-based vehicles. Such air-ground UAVs have a variety of applications, ranging from military and emergency services to recreational and commercial uses. There are a number of advantages of such airground vehicles:

[0007] - Air-ground vehicles can navigate across both air and ground, making them highly versatile in a wide range of environments. They can switch between flying over obstacles or traffic on the ground, offering a significant advantage in situations where either terrain presents a challenge. - These vehicles can reach areas that are difficult for traditional vehicles, whether it is remote, rugged terrain where land vehicles might struggle or places where roads do not exist.

[0008] - Air-ground vehicles can be more economical to operate than a conventional UAV, which often require extensive charging, maintenance, and facilities. They provide a good balance between ground and aerial propulsion power demand. They can use a lower power for ground movement and switch to a higher power for aerial operations only if necessary, thereby reducing power consumption.

[0009] - The ability to seamlessly transition between air and ground makes air-ground vehicles highly adaptable in increasingly complicated urban, indoor and weather conditions. They can fly over urban areas and land to reach more specific destinations on the ground.

[0010] - In certain hazardous cases like floods, traffic congestion, or natural disasters, air-ground vehicles can avoid potential hazards on the ground by taking flight, reducing the risk of accidents and damage.

[0011] - The dual capabilities of these vehicles offer a redundancy advantage. If one mode (ground or air) faces a failure or issue, the vehicle can switch to the other mode to continue its operation, enhancing safety.

[0012] Thus, air-ground vehicles offer numerous advantages, especially in terms of flexibility, efficiency, and adaptability. They are particularly valuable in areas where traditional vehicles or aircraft may be inefficient or impractical. As technology continues to evolve, the potential applications for air-ground vehicles expand, providing greater opportunities for improving transportation systems, responding to emergencies, and reducing environmental impacts.

[0013] US 2017 / 0210468 A1 discloses an unmanned flying robotic object that contains a wheeled mechanism that encircles its fixedly arranged spherical exoskeleton. This feature allows the flying spherical vehicle to readily transform into a ground manoeuvrable vehicle. A robotic motor with differential speed capability is used to operate each wheel to provide ground maneuverability. A disadvantage of this knows vehicle is that ground propulsion is realized with a complicated drive and structure, thereby representing considerable additional weight for the vehicle. A limited internal space also results in limited flying capabilities. The propeller circles do not cover the area of the sphere, so the device has to have an inefficiently large envelope size. Furthermore, the structure does not allow to position a camera or an image capture device with has an undisturbed field of view during operation.

[0014] US 2014 / 0131507 A1 discloses a vehicle capable of both aerial and terrestrial locomotion. The terrestrial and aerial vehicle includes a flying device with one or more rotors and a free-rolling rolling cage connected to the flying device by at least one revolute joint. The free-rolling rolling cage at least partially surrounds the flying device and is not separately powered. US 2014 / 0319266 A1 discloses an aerial micro-drone vehicle, having a fixed wing with rotors and freely rotating wheels for traveling on the ground, which are attached to the side ends of a section of the wing. A disadvantage of these known vehicles is that ground propulsion is realized with rotors, thereby ground propulsion is characterized by a relatively high power consumption, and free rolling cages or wheels do not provide efficient ground maneuverability.

[0015] US 2016 / 0130000 A1 discloses an unmanned air-ground vehicle which includes a frame having a centre portion connecting two substantially parallel transversely spaced apart track supports. Tracks that generally form loops are disposed about the track supports. Track drive motors are connected to the frame and configured to propel the tracks about the track supports. A plurality of propellers, each having propeller drive motors, are attached to the frame and disposed within the loops formed by the tracks. The tracks are configured to propel the vehicle in a ground mode while the propellers are configured to propel the vehicle in a flying mode. A disadvantage of this vehicle is that ground propulsion is realized by complicated and thereby heavy trach drives, which do not provide a protecting structure for the rotors.

[0016] A continuing need exists for improvements of unmanned aerial vehicles with ground mobility for a variety of applications. There is a special need for a solution that enables excellent ground mobility, a lightweight and protecting structure, and undisturbed image capture. There is also a need for a robotic aircraft that does not suffer from the disadvantages of the prior art. Accordingly, there exists a real need for a system that would address and solve the above-described problems.

[0017] DISCLOSURE OF INVENTION

[0018] It is an object of the invention to provide an unmanned aerial vehicle that eliminates disadvantages of prior art solutions as much as possible. Another objective of the invention is to improve the utilization of UAVs by enabling excellent ground mobility with a lightweight and protecting ground-propulsion structure, and an undisturbed image capture.

[0019] The above and other objects have been achieved by the unmanned aerial vehicle according to claim 1 . Preferred embodiments are defined in the dependent claims.

[0020] None of the prior art solutions contains all the elements of the inventive solution, namely an outer protective and ground locomotion grid structure consisting of two parts (“wheels”), wherein the grid parts can be rotated separately, and two motors, e.g. electric motors are applied to rotate the grid parts, to move the UAV on the ground.

[0021] Combining the terrestrial and aerial locomotion modes in a hybrid design incorporates the advantages of both modes in a single system. Adding a reliable and protective terrestrial locomotion structure to the aerial vehicle provides improved efficiency, which extends operation time and range. On the other hand, adding flight capabilities to a terrestrial system eliminates the problem of obstacle negotiation. When an obstacle is encountered, the system can easily fly over it.

[0022] The invention has a simple design. This makes it easy and low cost to manufacture. Furthermore, any regular flying rotorcraft system, for which there are many well developed samples available, can be employed in the inventive UAV.

[0023] BRIEF DESCRIPTION OF DRAWINGS

[0024] Characteristics, objectives, and advantages of embodiments of the subject matter will become apparent from the following description, which is given solely by way of illustration, is non-limiting, and is to be read with reference to the appended drawings in which

[0025] Fig. 1 schematically illustrates a spatial view of an unmanned aerial vehicle with ground mobility according to an embodiment of the invention,

[0026] Fig. 2 schematically illustrates a top view of the embodiment of Fig. 1 ,

[0027] Fig. 3 schematically illustrates a front view of the embodiment of Fig. 1 ,

[0028] Fig. 4 schematically illustrates a side view of the embodiment of Fig. 1 , and

[0029] Fig. 5 illustrates a flowchart of an autonomous operation of the embodiment of Fig. 1.

[0030] MODES FOR CARRYING OUT THE INVENTION

[0031] The subject matter disclosed herein comprises an unmanned aerial vehicle (UAV) with ground mobility. During flight, the rotor actuator(s) provide enough lift to overcome the weight of the vehicle, and the system functions as a regular flying system; it can move by rolling or pitching and change direction by changing its yaw angle. For ground locomotion, specially formed and separately driven wheels are provided.

[0032] Fig. 1 depicts a preferred embodiment of an UAV with ground mobility, which has autonomous, semi-autonomous and manual control operating modes. The UAV can be remotely controlled by a human and can also operate autonomously or semi- autonomously. If the UAV loses communication, it automatically switches to autonomous mode. The UAV is capable to autonomously perform its tasks and to return to a basis. In remote control mode it is preferably possible to choose between ground mode and air mode via a switch. In autonomous mode the program itself decides which mode to use.

[0033] The UAV comprises a base structure 10; other parts of the UAV are fixed or attached directly or indirectly to the base structure 10.

[0034] A central control unit 11 , preferably with remote control and autonomous operation capabilities serves for controlling the UAV. A plurality of rotors 12, each having an assigned rotor drive 13 provide flying capabilities and are controlled by the central control unit 11. An image capturing device 14, preferably a camera is also attached to the base structure 10 and is preferably controlled by the central control unit 11. Of course, more than one image capturing devices 14 can also be attached. A battery 15 supplies power for all active components of the UAV.

[0035] The UAV further comprises a first wheel drive motor 16 attached to the base structure 10 and controlled by the central control unit 11 , a first grid wheel structure 17 driven by the first wheel drive motor 16 to rotate around an axis of rotation, a second wheel drive motor 18 attached to the base structure 10 and controlled by the central control unit 11 , and a second grid wheel structure 19 driven by the second wheel drive motor 18 to rotate around the same axis of rotation as the first grid wheel structure 17. In ground operation, the two electric wheel drive motors 16, 18 provide propulsion either directly or through a gearbox. The two electric wheel drive motors

[0036] 16, 18 can be controlled separately from each other, thereby ensuring high manoeuvrability. In flight mode, a multirotor propulsion manoeuvres the UAV in the air.

[0037] The material of the lattice structures, i.e. of the first and second grid wheel structures

[0038] 17, 19 can be e.g. a composite material composed of woven fiberglass cloth with an epoxy resin binder that is flame resistant, such as FR4, another type of composite, carbon fibre composite, polycarbonate, a polymer or a light metal, such as titanium or aluminium. Segments of the grid structures can be formed e.g. by contour milling from a sheet material.

[0039] Steering of the UAV is achieved by varying the speed of the propellers or rotors 12, which preferably rotate in opposite directions in pairs. To overcome certain obstacles, it may be necessary to use both modes simultaneously. For example, to climb a steep slope, the rotor drives 13 can be turned on to assist the ground drive. Thus, ground and air propulsion can also be operated together.

[0040] In the direction of the axis of rotation, the base structure 10 has a first end portion and an opposite second end portion at which the first and second grid wheel structures 17, 19 are rotatably attached, respectively. Each of the first and second grid wheel structures 17, 19 at least partly surrounds at least one of the rotors 12. The first and second grid wheel structures 17, 19 thereby protect the rotors 12 from obstacles and collisions during flight and taxiing, as well as the UAV against shocks of aggressive landings or crashes.

[0041] The UAV has an upright ground position in which a centre of gravity of the UAV is below the axis of rotation which allows an energy-efficient propulsion on the ground. The first and second grid wheel structures 17, 19 have the same largest radius which extends beyond other parts of the UAV which are at a lower height than the axis of rotation in said upright ground position. In this way, there are no protruding parts in the lower part of the UAV that could hit the ground even if there is some extent of rocking of the UAV at dynamic rolling situations.

[0042] The first and second grid wheel structures 17, 19 are arranged with a spacing from each other along said axis of rotation, and the image capturing device 14 is arranged in a centered position with respect to said spacing. This enables an undisturbed view for the camera. In a preferred embodiment, a field of view of the image capturing device 14 is directed away from the axis of rotation, and said spacing between the first and second grid wheel structures 17, 19 is selected to ensure that the first and second grid wheel structures 17, 19 are outside of the field of view of the image capturing device 14.

[0043] The first and second grid wheel structures 17, 19 are preferably formed as or comprise hemispheric or oblate hemispheric grid structures. Such grid structures result in a ball-like overall shape for the UAV, which is a highly preferred embodiment from the aspects of external protection. The first and second grid wheel structures 17, 19 provide physical, mechanical protection for the rotors and for the UAV itself for the case of a collision, and also enable ground propulsion. The first and second grid wheel structures 17, 19 may also be formed as or comprise partial spheric, partial oblate spheric, cy I indric or toroidal grid structures. The first and second grid wheel structures 17, 19 or rolling lattice structures can be rotated separately, so that when the UAV is on the ground, these separate structures can ensure the drone's progress, for which two separate electric motors and propulsion are used.

[0044] The base structure 10 preferably comprises a polygon tube structure formed from tube segments and symmetrically to a middle plane between the first and second end portions of the base structure 10. Each of the rotor drives 13 and of the first and second wheel drive motors 16, 18 is arranged preferably at a respective vertex of the polygon tube structure, and each of the rotor drives 13 and of the first and second wheel drive motors 16, 18 is connected to the central control unit 11 via electric cables arranged within the polygon tube structure.

[0045] A preferred embodiment is characterized by an upright ground position in which each of the rotor drives 13 are below the polygon tube structure. The polygon tube structure has preferably a horizontal arrangement in said upright ground position. Furthermore, in said upright ground position the battery 15 is also preferably below the polygon tube structure, and can be arranged in a suspended way and with a spacing from the polygon tube structure. In such a way, enhanced stability is ensured for the ground propulsion.

[0046] The base structure 10 preferably comprises a hexagonal polygon tube structure having three planes of symmetry. The first and second wheel drive motors 16, 18 can be arranged at two opposite vertices of the polygon tube structure, respectively, and the rotor drives 13 can be arranged at the remaining vertices of the polygon tube structure, respectively. The central control unit 11 may be arranged as a bridging insert between two opposite segments of the polygon tube structure, and the battery 15 may be suspended onto and with a spacing from the central control unit 11.

[0047] Figs. 2 to 4 depict the UAV in top, front and side views in the upright ground position, respectively. Fig. 5 illustrates a flowchart of an autonomous operation of the embodiment of Fig. 1 . In step 20 a notification arrives for the UAV to start operation. After the take-off in step 21 and approaching the target area in step 22, the UAV lands in step 23 and switches to rolling mode in step 24.

[0048] Step 25 represents a mapping operation carried out by the UAV by means of the image capturing device 14. It is checked in step 26 whether the given task is completed, and if not, it is checked in step 27 whether there are any obstacles that can not be rolled over. If yes, the UAV switches to flying mode in step 28, takes off in step 29, flies over the obstacle in step 30, thereafter lands in step 31 and returns to step 24 to switch to rolling mode again.

[0049] If the task is ready, the UAV switches to flying mode in step 32, takes off in step 33 and returns to the base in step 34.

[0050] The inventive UAV is thus a structure that can roll and fly, and is especially suitable for indoor use, for penetration and mapping. The inventive UAV is capable of autonomously building a spatial model of an interior of an object or identifying targets, while stealthily traversing the interior of the object, most often in a rolling mode, interrupted by short flight cycles. Civilian applications of the UAV include e.g. mine mapping, search and rescue missions, spatial modelling of building interiors, health assessment of industrial facilities, camera surveillance and educational applications. Defence / police applications of the UAV include e.g. reconnaissance of damaged or dangerous buildings or hostile areas, hostile objects, preparation of intrusion plans, locating of persons or objects, support of mobile commando units, disaster management, fire brigade operations.

[0051] The inventive UAV can be produced in a small size, such as that of soccer ball, with impact and shock resistance, with a minimum 10 minutes flight time, minimum 1 hour taxi time with a low noise emission in rolling mode, in a quadrocopter configuration. Such parameters generally enable to accommodate and to carry the typical on-board equipment necessary for the desired operations, such as TOF (time of flight) camera, telemetry, sensor data and video signal transmission, on-board computer, flight controller. Image processing, artificial Intelligence supported 3D mapping, situation interpretation may be programmed into the on-board computer or central control unit 11 .

[0052] The inventive UAV is equipped with one or more image capturing devices 14, such as camera sensor(s) that can be viewed without distractions, and wheels driven by independent motors to ensure ground travel and turning. The wheels also protect the propellers from obstacles and collisions during flight and taxiing, as well as the UAV against shocks of aggressive landings or crashes.

[0053] This written description uses examples to disclose the subject matter, and also to enable any person skilled in the art to practice the subject matter, including making and using any devices or systems and performing any incorporated methods. The patentable scope is defined by the claims and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Claims

CLAIMS1. An unmanned aerial vehicle (UAV) with ground mobility, comprising a base structure (10), and attached to the base structure (10)- a central control unit (11 ),- a plurality of rotors (12), each having a rotor drive (13) controlled by the central control unit (11 ),- an image capturing device (14), and- a battery (15), wherein the UAV further comprises- a first wheel drive motor (16) being attached to the base structure (10) and being controlled by the central control unit (11 ),- a first grid wheel structure (17) driven by the first wheel drive motor (16) to rotate around an axis of rotation,- a second wheel drive motor (18) being attached to the base structure (10) and being controlled by the central control unit (11 ), and- a second grid wheel structure (19) driven by the second wheel drive motor (18) to rotate around the same axis of rotation as the first grid wheel structure (17), and wherein- in the direction of the axis of rotation, the base structure (10) has a first end portion and an opposite second end portion at which the first and second grid wheel structures (17, 19) are rotatably attached, respectively,- each of the first and second grid wheel structures (17, 19) at least partly surrounds at least one of the rotors (12),- the UAV has an upright ground position in which a centre of gravity of the UAV is below the axis of rotation, the first and second grid wheel structures (17, 19) having the same largest radius which extends beyond other parts of the UAV which are at a lower height than the axis of rotation in said upright ground position, and- the first and second grid wheel structures (17, 19) are arranged with a spacing from each other along said axis of rotation, and the image capturing device (14) is arranged in a centered position with respect to said spacing.

2. The UAV according to claim 1 , wherein a field of view of the image capturing device (14) is directed away from the axis of rotation, and said spacing between the first and second grid wheel structures (17, 19) is selected to ensure that the first and second grid wheel structures (17, 19) are outside of the field of view of the image capturing device (14).

3. The UAV according to claim 1 or claim 2, wherein the first and second grid wheel structures (17, 19) are formed as or comprise hemispheric or oblate hemispheric grid structures.

4. The UAV according to claim 1 or claim 2, wherein the first and second grid wheel structures (17, 19) are formed as or comprise partial spheric, partial oblate spheric, cy I indric or toroidal grid structures.

5. The UAV according to any of claims 1 to 4, wherein the base structure (10) comprises a polygon tube structure formed symmetrically to a middle plane between the first and second end portions of the base structure (10), wherein each of the rotor drives (13) and of the first and second wheel drive motors (16, 18) is arranged at a respective vertex of the polygon tube structure, and wherein each of the rotor drives (13) and of the first and second wheel drive motors (16, 18) is connected to the central control unit (11 ) via electric cables arranged within the polygon tube structure.

6. The UAV according to claim 5, wherein in said upright ground position each of the rotor drives (13) are below the polygon tube structure.

7. The UAV according to claim 5 or claim 6, wherein in said upright ground position the battery (15) is below the polygon tube structure8. The UAV according to claim 7, wherein the battery (15) is arranged in a suspended way and with a spacing from the polygon tube structure.

9. The UAV according to claim 5, wherein the base structure (10) comprises a hexagonal polygon tube structure having three planes of symmetry, wherein the first and second wheel drive motors (16, 18) are arranged at two opposite vertices of the polygon tube structure, respectively, and the rotor drives (13) are arranged at the remaining vertices of the polygon tube structure, respectively.

Images