DESC:FIELD OF INVENTION
The present invention relates to an unmanned aerial vehicle (UAV). More particularly, the present invention relates to a light weight, flexible UAV capable of flying in severe climatic conditions. Additionally the present invention relates to a light weight flexible UAV with high strength and rigidity.

BACKGROUND OF INVENTION
An unmanned aerial vehicle or UAV commonly known as a drone is an aircraft without a human pilot aboard. The flight of the UAVs may operate with various degrees of autonomy either under remote control by a human operator, or fully or intermittently autonomous by onboard computers. With the rapid increase in technology, UAVs are being used in a wide range of applications. A UAV, which differs widely from an aircraft, is in its best mode, when it is designed to be light in weight. Light weight unmanned air vehicles are meant for various uses such as surveillance and package delivery especially in military and law enforcement. It therefore becomes necessary that every component in the physical design of a UAV is of utmost importance in addition to its aerodynamic characteristics.

US9616997 B2 discloses a combined submersible vessel and unmanned aerial vehicle comprising a body structure, wing structure, atleast one vertical stabilizer structure and one horizontal stabilizer structure. A propulsion system is coupled to the body and is configured to propel the flying submarine in both airborne flight and underwater operation.

US2016221676 A1 discloses a quadrotor UAV including ruggedized, integral-battery, load bearing body, two arms on the load bearing body, each arm having two rotors, a control module, a payload module mounted on the control module and skids configured as landing gear. The control module is configured to operate as an UAV, unmanned (water) surface vehicle an unmanned underwater vehicle depending on the type of arms.

US20170023939 A1 discloses a system for controlling an unmanned aerial vehicle over a cellular network and provides capability for UAV operators to control UAV without the requirement of the operator within limited range of the UAV. This is enabled by the coupling of the control station to the cellular network which in turn is coupled to the UAV. It further provides a streaming capability in addition to modular circuitry unit designed for various purposes in flight. It specifically discloses a system to control the UAV.

US20170225782 A1 discloses a stowable and deployable unmanned aerial vehicle (UAV), and associated systems. The UAV includes a main body, frames carried by the main body, motors carried by the frames. In the stowed configuration the main body pivotably connected to the second body portion. The modular electronics unit of the UAV includes a camera, a battery, and vehicle controller. The modular electronics units can be configure to be removably connected to and disconnected from the UAV and other vehicles.

CN106132827 discloses a UAV base station system for automated battery pack exchange. The invention discloses autonomous operation of UAV without need for user intervention for exchanging UAV battery pack.
JP2010132280 discloses UAV for VTOL or vertical takeoff and landing comprising high strength composite structural parts made up of wood or solid metal and light weight aerodynamic foam portions which provide low cost and light weight UAV. This design is not a light weight design and is also complex in structure.

CA2516614 C discloses a portable unmanned air vehicle and launcher system which includes a foldable unmanned air vehicle with pressure tube, a launch gas reservoir for holding launch gas, a free piston within the launch tube. When the launch gas is released in the launch gas reservoir it forces the free piston from initial position to end position, causes the air vehicle launch.

One of the main aspects of increasing efficiency of an UAV is to reduce its weight or mass. The lighter the UAV, longer will be the maximum flight time and bigger the payload. To improve the system of transportability, to increase the payload and aid the UAV for operations with increased flight time or duration there is a need to design UAV of light weight and high quality and reliability. These objectives are not met by the prior art, discussed herein, being either complex in design and with a higher in All-Up-Weight. Accordingly, there exists a need to design a light weight flexible UAV without compromising on strength and rigidity, with less assembled parts and reduced overall weight.

OBJECTS OF INVENTION
It is the primary object of the present invention to provide an Unmanned Aerial Vehicle (UAV) which is light weight, sturdy, capable of flight in extreme climatic conditions.

It is another object of the invention to provide an Unmanned Aerial Vehicle (UAV) to carry communication and data or image acquisition payloads.

It is another object of the invention to provide an Unmanned Aerial Vehicle (UAV) that is stiff and strong and enables comfortable pitch, roll and yaw rotations.

It is another object of the invention to provide an Unmanned Aerial Vehicle (UAV) for extended flight duration.

It is another object of the invention to design an Unmanned Aerial Vehicle (UAV) that is able to distribute equal power to all motors at equal speeds.

It is another object of the invention to design an Unmanned Aerial Vehicle (UAV) that is able to be driven in a given direction using GPS.

It is another object of the invention to design a Unmanned Aerial Vehicle (UAV) that is able to receive input from a remote location.

It is another object of the invention to design a Unmanned Aerial Vehicle (UAV) that can absorb base excitations as the motors are functioning.

It is another object of the invention to design a Unmanned Aerial Vehicle (UAV) that doesn’t transmit vibrations to the payload holding plate and its components.
These and other objects and advantages of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings.

SUMMARY OF INVENTION
One or more of the problems of the conventional prior art may be overcome by various embodiments of the present invention.

It is the primary aspect of the present invention to provide a light weight flexible unmanned aerial vehicle (UAV) without compromising on strength and rigidity of said UAV.

It is another aspect of the present invention to provide a light weight flexible UAV with increased stiffness to enable comfortable pitch, roll and yaw rotations.

It is another aspect of the present invention to provide a light weight flexible UAV with rigid support to all connected parts.

It is another aspect of the present invention to provide an Unmanned Aerial Vehicle (UAV) comprising:
top plate;
bounding box [2];
rotor base frame;
motors [3];
arms [5];
electronic speed controllers (ESC);
power distribution board (PDB);
Global positioning system (GPS);
motor mounting assembly;
battery fixture assembly;
payload holding plate;
payload mounting plate;
flight controller;
Global positioning system (GPS); and
landing gear/ one or more legs [6];
wherein the top plate supports the flight controller,
wherein the rotor base frame comprises a base plate [1] and one or more arms [5],
wherein a motor [3] with propeller is assembled onto each of the arms [5] using motor mounting assembly to generate thrust,
wherein the battery fixture assembly is provided with atleast two support members to hold at least one battery on the base plate,
wherein the payload holding plate is positioned below the battery fixture assembly which provides structure to accommodate gimbal,
wherein the flight controller contains the Inertial Measurement Unit (IMU) and is fastened to the top plate,
wherein the landing gear [6] is the load bearing and supporting structure for easy mounting of the payload,
wherein payloads can be mounted on the payload mounting plate, and
wherein one end of each of the legs [6] are connected to the rotor base frame and other end of the legs support the UAV during takeoff and landing.

It is another aspect of the present invention, wherein the motors [3] are DC Brushless motors and are closely packed to the speed controller units to avoid untangling of the connectors at high speed.

It is another aspect of the present invention, wherein the bounding box [2] is of aerodynamic design, made up of high density polystyrene and mounted on top plate to protect the top plate and flight controller from external disturbances.

It is another aspect of the present invention, wherein the battery fixture assembly comprises upper and lower support plates, guide vanes and battery holding plate.

It is another aspect of the present invention, wherein the battery fixture assembly holds at least one battery [4] in a plug and play setup on to the base plate for easy egress and ingress of the battery.

It is another aspect of the present invention, wherein the payload holding plate is provided with one or more slots to reduce the weight of the payload holding plate.

It is another aspect of the present invention, wherein the payload mounting plate is attached to the payload holding plate through one or more dampers to hold the payload in position without transmitting any vibration to said payload.

It is another aspect of the present invention, wherein the payload mounting plate is attached to the payload holding plate through one or more dampers to hold the payload in position without transmitting any vibration to said payload.

It is another aspect of the present invention, wherein the said payload is a camera.

It is another aspect of the present invention, wherein each of the legs [6] includes flat portion and curved portion, the flat portion is provided with at least two equally spaced slots to connect with the rotor base frame, said slots provide rigidity and load distribution onto the legs.

It is another aspect of the present invention, wherein the distance between lower most point on the curved portion of the leg and ground is of pre-defined length for trouble free loading and unloading of the payloads.

It is another aspect of the present invention, wherein the curved portions of the legs [6] in the landing gear absorbs shocks and reduces transmissibility of vibration to structures attached to it primarily during landing of the UAV.
It is another aspect of the present invention, wherein the Inertial Measurement Unit (IMU) houses one or more sensors, processors and external input/ aux ports to perform information storage and signal accession.

It is another aspect of the present invention, wherein the power distribution board is the electro-mechanical component that distributes power to motors and flight controller.

It is another aspect of the present invention, wherein the Global Positioning System (GPS) module is fastened onto the base plate through a non-conductive stand, away from the electronics unit.

It is another aspect of the present invention, wherein the electronic speed controller (ESC) regulates current influx to the motor [3].

It is another aspect of the present invention, wherein the power distribution board distributes power to motors [3] and flight controller.

It is another aspect of the present invention, wherein the arms [5] or the wings are tubular with circular cross section and house the motor and propellers.

It is another aspect of the present invention, wherein the motor mounting assembly [8] further comprises of motor base plate, motor support plate, a frame and speed controller holding plate.

It is another aspect of the present invention, wherein the Landing gear [6] is preferably made up of Nylon.

It is another aspect of the present invention, wherein the landing gear performs the functions of load bearing, easy mounting of the payload, absorb shock and reduce transmissibility of vibration during incorrect/ crash landing.

It is another aspect of the present invention, wherein the components of UAV are preferably made of carbon fibre material.

It is another aspect of the present invention, wherein the UAV is capable of carrying communication and image data acquisition payloads.

BRIEF DESCRIPTION OF DRAWINGS
So that the manner in which the features, advantages and aspects of the invention, as well as others which will become apparent, may be understood in more detail, more particular description of the invention briefly summarized above may be had by reference to the embodiment thereof which is illustrated in the appended drawings, which form a part of this specification. It is to be noted, however, that the drawings illustrate only a preferred embodiment of the invention and is therefore not to be considered limiting of the invention's scope as it may admit to other equally effective embodiments.

Figure 1: illustrates the unmanned aerial vehicle (UAV) according to the present invention depicting Base plate [1], Bounding box [2], Motors [3], Battery [4], Arms [5], Landing gear or skid [6].
Figure 2: illustrates the bottom view of the unmanned aerial vehicle (UAV) according to the present invention depicting the battery plate [7], motor [3] and motor mounting assembly [8].
Figure 3: illustrates a sketch of landing gear/leg according to the present invention depicting section A [6A], section B [6B] and section C [6C] undergoing a load. R222 is the outer radius and R210 is the inner radius of the landing gear.

DETAILED DESCRIPTION OF THE INVENTION
The present invention as herein described relates to an unmanned aerial vehicle (UAV). Further the present invention relates to a light weight, flexible and sturdy UAV.
Referring to figures 1 and 2, an Unmanned Aerial Vehicle comprising Base plate [1], Bounding box [2], Motors [3], Battery [4], Arms [5], Landing gear or skid [6], Battery plate [7], Motor Unit [8] is illustrated.

The UAV comprises of the following parts for for its smooth flight and functioning. The structural design mainly comprises Frame, Motors, propellers, Electronic Speed Controllers, Flight Controller, Power System (Battery), power distribution board, Arms, Global Positioning System or GPS and landing gear.

All major components like the frame, propellers, arms and landing gear are made up of carbon fiber that imparts stiffness, rigidity and support to all connected parts. Carbon fiber was chosen for its low weight and lateral stiffness.

The top plate is designed to support the Flight controller so that the sensors and processors are devoid of any disturbances. The base plate [1] geometry is designed to accommodate and provide support to all the four arms or the UAV, the GPS, Power distribution board and additional payload components such as receiver and transmitter of the telemetry kit. The bounding box [2] is of aerodynamic design, made up of high density polystyrene that provides it light weight and ease of manufacture. It covers the top plate and flight controller to protect it from external disturbances. The battery fixture assembly is of layered stack approach and comprises of the parts: upper support plates, Lower Support Plates, guide vanes and Battery holding plate [7]. The upper support plate on right hand side is symmetrical with the upper support plate on the left hand side about the roll axis of the quad-rotor, similarly the lower support plate on right hand side is symmetrical with the lower support plate on the right hand side about the roll axis. This design specifically achieves equivalent mass distribution of the entire fixture, avoids unnecessary joining of parts which can cause an increase in All-Up-Weight.
Guide Vanes are positioned on both sides of the battery in-between the upper and lower support plates. Guide vanes are also symmetrical about the roll axis of the quad. The upper and lower support plates are of the same dimensions 3mm thick, 20mm width & 180mm long. Length and thickness of the guide vanes are the same as that of the support plates while the width is 12.5mm. The Battery holding plate [7] has dimensions of 215*130*3 (L*W*H) mm. The Battery holding plate [7] slides through the space between left and right support plates and supported by the guide vanes. The rear end of the battery support plate is bolted to another plate stacked below the battery fixture assembly. Symmetrical slots on the battery holding plate [7] have been provided so as to reduce the weight of the plate and also to provide air cooling to the battery. The battery [4] is tightened to the battery holding plate [7] using Velcro tapes at the front as well as rear end. Slots in the battery holding plate [7] can accommodate any Lithium Polymer battery having dimensions as mentioned below: Length: 165-195mm, Width: 65-91 mm, Depth: 50-64 mm.
Camera holding Plate is a support plate below the battery fixture assembly which provides structure to accommodate the gimbal and further onto the camera mounting plate. The camera holding plate’s geometry is similar to the battery holding plate with slots provided wherever necessary without compromising on strength but reducing its own weight. This plate is also made of carbon fiber due to its high strength low weight property.

Camera Mounting Plate is a smaller plate attached to the camera holding plate through rubber dampers in order to hold the camera in position without transmitting any vibration to the payload (camera).

Motors [3] are Tarot 5008-340 kv, DC Brushless motors which convert the electrical energy from the battery to mechanical energy to generate thrust. The motors [3] were assembled onto the arms [5] using motor mounting assembly [8] which consists of motor base plate, motor support plate and ESC holding section. Motor mount assembly [8] also consists of a frame which extends outwards from the arms [5] and prevents the motors from having any sideways motion. These frames have a circular section at the arm end to enable arms [5] to fit inside this gap on the frame and are have a rectangular cross section at the motor end to support ESC and motor base mounts.

Propellers are Carbon Fiber Propellers which are 18 inches long and generate a pitch of 5.4 inches are fastened atop the shaft of the DC brushless motor. These propellers are capable of generating a maximum thrust of 3.6 kgs at full acceleration.

ESCs are Electronic Speed Controllers regulate the amount of current that goes into each motor at defined frequencies. They receive Pulse Width Modulated (PWM) signals from the flight controller which contain the voltage and current that needs to be sent to the motor to rotate it.
Flight Controller is the heart of the UAV containing Inertial Measurement Unit (IMU) which consists of accelerometer sensor, gyroscopic sensor, barometric sensor & magnetometric sensor is fastened to the top plate. External ports on the Flight controller enable us to connect GPS, receiver, ESC & telemetry onto it. It contains the main processor which stores all the flight information, sends signals and receives inputs from the sensors to give directions to the UAV through ESC which in turn control the rotation speeds of the motor [3] to perform various flight maneuver operations.

The power system for the UAV is designed to accommodate Lithium polymer batteries. The UAV of the present invention can house batteries of sizes 165-195 mm in Length, 60-95 mm in width and 50-65 mm in depth. The batteries [4] provide DC (Direct current) power to the processor, ESC, motors & GPS. The power system of the UAV is battery operated.
Power Distribution Board or PDB is an electro-mechanical component which contains connectors needed to connect ESC to the battery [4]. It distributes the power from battery [4] to various motors [3] and the flight controller. It consists of strong fiber glass board acting as a insulating frame between the positive and negative sides of power supply. Gold pin connectors fixed onto the power distribution board connect to ESC to distribute power.

Arms/ Wings: Arms [5] long tubular members of circular cross section to house the motors and propellers. These are rigid members made of carbon fiber and are light in weight. They have been machined to meet the desired dimensions of the UAV so that agility of the UAV is not compromised.

Global Positioning System or GPS is a small electronic module capable of giving location of our UAV at all instants of time using satellite information. GPS gives us latitude, longitude and altitude data provided the magnetometer atop the GPS is not affected by magnetic disturbances. Hence the GPS is placed on non-conductive stand which is fastened onto the base plate [1].

Landing Gear: Landing Gear [6] is a nylon member designed to meet the following functionalities:
i. Load Bearing & Provide support to frames and arms of the aircraft.
ii. Provide enough space between ground & payload for easy mounting of Payloads.
iii. Absorb shock & reduce transmissibility of vibration to structures attached to it primarily during incorrect or crash landing.

The design of the landing gear with the desired principles involved the creation of a curved beam with rectangular cross section. The design is based on the premise that the entire weight of the quad rotor excluding the weight of the landing gear cannot exceed 2kg or 20 N. The landing gear is designed to have a flat portion section A [6A], curved portion section B [6B], and inclined portion of the leg section C [6C]. Section A [6A] is primary load bearing portion supporting one-fourth of the All-up-weight of the UAV. Section B [6B] is designed to absorb the shock and transmit shock waves along the cross sectional axis of the leg and not laterally thereby reducing failure of leg at the arm-leg-base plate assembly. Section C [6C] is the inclined portion making an angle of 60 degrees with horizontal. This inclination is meant to provide larger base area for the UAV to rest on and enable easy and flexible bending of legs at the time of sudden impact.
The curvature of the landing gear at section B [6B] has been designed with this particular dimension so as to withstand hard landings and buckle enough to not break but spring back to its original position. Increase the outer radius R222 would increase weight of the component and not provide enough springbuck while decreasing R210 would make the gear more flimsy at section B [6B] causing to fatigue earlier. ,CLAIMS:We Claim:
1. An Unmanned Aerial Vehicle (UAV) comprising:
top plate;
bounding box [2];
rotor base frame;
motors [3];
arms [5];
electronic speed controllers (ESC);
power distribution board (PDB);
Global positioning system (GPS);
motor mounting assembly [8];
battery fixture assembly;
payload holding plate;
payload mounting plate;
flight controller; and
landing gear/ legs [6],
wherein the top plate supports the flight controller,
wherein the rotor base frame comprises a base plate [1] and one or more arms [5],
wherein a motor [3] with propeller is assembled onto each of the arms [5] using motor mounting assembly [8] to generate thrust,
wherein the battery fixture assembly is provided with atleast two support members to hold at least one battery on the base plate [1],
wherein the payload holding plate is positioned below the battery fixture assembly which provides structure to accommodate gimbal,
wherein the flight controller contains the Inertial Measurement Unit (IMU) and is fastened to the top plate,
wherein the landing gear is the load bearing and supporting structure for easy mounting of the payload,
wherein payloads can be mounted on the payload mounting plate, and
wherein one end of each of the legs are connected to the rotor base frame and other end of the legs support the UAV during takeoff and landing.

2. The UAV as claimed in claim 1, wherein the motors [3] are DC Brushless motors and are closely packed to the speed controller units to avoid untangling of the connectors at high speed.

3. The UAV as claimed in claim 1, wherein the bounding box [2] is of aerodynamic design, made up of high density polystyrene and mounted on top plate to protect the top plate and flight controller from external disturbances.

4. The UAV as claimed in claim 1, wherein the battery fixture assembly comprises upper and lower support plates, guide vanes and battery holding plate.

5. The UAV as claimed in claim 1, wherein the battery fixture assembly holds at least one battery [4] in a plug and play setup on to the base plate for easy egress and ingress of the battery [4].

6. The UAV as claimed in claim 1, wherein payload holding plate is provided with one or more slots to reduce the weight of the payload holding plate.

7. The UAV as claimed in claim 1, wherein the payload mounting plate is attached to the payload holding plate through one or more dampers to hold the payload in position without transmitting any vibration to said payload.

8. The UAV as claimed in claim 1, wherein the said payload is a camera.

9. The UAV as claimed in claim 1, wherein each of the legs [6] includes flat portion and curved portion, the flat portion is provided with at least two equally spaced slots to connect with the rotor base frame, said slots provide rigidity and load distribution onto the legs [6].

10. The UAV as claimed in claim 9, wherein the distance between lower most point on the curved portion of the leg and ground is of pre-defined length for trouble free loading and unloading of the payloads.

11. The UAV as claimed in claim 9, wherein the curved portions of the legs in the landing gear [6] absorbs shocks and reduces transmissibility of vibration to structures attached to it primarily during landing of the UAV.

12. The UAV as claimed in claim 1, wherein the Inertial Measurement Unit (IMU) houses one or more sensors, processors and external input/ aux ports to perform information storage and signal accession.

13. The UAV as claimed in claim 1, wherein the power distribution board is the electro-mechanical component that distributes power to motors [3] and flight controller.

14. The UAV as claimed in claim 1, wherein the Global Positioning System (GPS) module is fastened onto the base plate through a non-conductive stand, away from the electronics unit.

15. The UAV as claimed in claim 1, wherein the electronic speed controller (ESC) regulates current influx to the motor [3].

16. The UAV as claimed in claim 1, wherein the power distribution board distributes power to motors and flight controller.

17. The UAV as claimed in claim 1, wherein the arms [5] or the wings are tubular with circular cross section and house the motor and propellers.
18. The UAV as claimed in claim 1, wherein the motor mounting assembly [8] further comprises of motor base plate, motor support plate, a frame and speed controller holding plate.

19. The UAV as claimed in claim 1, wherein the Landing gear [6] is preferably made up of Nylon.

20. The UAV as claimed in claim 1, wherein the landing gear [6] performs the functions of load bearing, easy mounting of the payload, absorb shock and reduce transmissibility of vibration during incorrect/ crash landing.

21. The UAV as claimed in claim 1, wherein the components of UAV are preferably made of carbon fiber material.

22. The UAV as claimed in claim 1, wherein the UAV is capable of carrying communication and image data acquisition payloads.