Unmanned aerial vehicle

Abstract

A vertical take-off and landing (“VTOL”) unmanned aerial vehicle (“UAV”) system and a method of controlling the same, wherein such method controls the stability and maneuverability of the VTOL UAV by manipulating the speeds of the propellers at each rotor. The VTOL UAV includes a body with three extending arms, wherein each of such arms is aligned and fixed at a certain angle from a central axis passing through the body. Each extending arm is equipped with a rotor with propellers. The rotors are sufficient to control the yaw of the UAV, and there is no need for coaxial rotors or an extra servo-motor in order to control the yaw of the UAV, thus reducing the cost and the weight of the UAV.

1 . An unmanned aerial vehicle (“UAV”) comprising:
 a main body having a front portion and a rear portion, wherein said main body is bifurcated by a line of symmetry; 
 first, second, and third similar arms extending radially from said main body, wherein said first and second arms extend from said front portion and are positioned relative to each other on opposite sides of said line of symmetry, and wherein said third arm extends from said rear portion along said line of symmetry; and 
 a single rotor positioned on each of said first, second, and third arms. 
 
     
     
         2 . The unmanned aerial vehicle as recited in  claim 1 , wherein said single rotors positioned on said first and second arms rotate in a similar direction, and wherein said single rotor positioned on said third arm rotates in an opposite direction. 
     
     
         3 . The unmanned aerial vehicle as recited in  claim 1 , wherein said UAV is configured to achieve maneuverable flight with only said single rotors positioned on said first, second, and third arms. 
     
     
         4 . The unmanned aerial vehicle as recited in  claim 2 , wherein said single rotors positioned on said first and second arms produce similar amounts of torque and lift while said rotor positioned on said third arm produces twice the amount of torque produced by either of said other two single rotors. 
     
     
         5 . The unmanned aerial vehicle as recited in  claim 1 , further comprising a DC motor coupled to each single rotor and positioned on said first, second, and third arms. 
     
     
         6 . The unmanned aerial vehicle as recited in  claim 1 , further comprising a plurality of (“PID”) controllers configured to control a set of parameters, including altitude, roll, pitch, and yaw, of said UAV system. 
     
     
         7 . The unmanned aerial vehicle as recited in  claim 6 , wherein said plurality of PID controllers are four, each configured to control at least one parameter of said set of parameters with equivalent execution rates of roll and pitch control loops, and a higher execution rate of a yaw control loop than said execution rates of said roll and pitch control loops. 
     
     
         8 . The unmanned aerial vehicle as recited in  claim 1 , further comprising three command mixers configured to mix outputs of said PID controllers, wherein said mixed outputs are sent to a plurality of rotor controllers. 
     
     
         9 . The unmanned aerial vehicle as recited in  claim 1 , wherein said UAV does not include any servo-motors coupled to said single rotors so that said single rotors are attached to said arms in a fixed manner. 
     
     
         10 . The unmanned aerial vehicle as recited in  claim 1 , wherein said single rotors are not coaxial rotors. 
     
     
         11 . A method for controlling a UAV system comprising:
 comparing, by at least one controller, a plurality of actual parameters versus a plurality of desired parameters;   identifying, by the at least one controller, correction values for the compared parameters;   mixing, by at least one command mixer, the correction values; and   communicating the mixed values at the at least one command mixer to a corresponding rotor controller of said UAV system.   
     
     
         12 . The method as recited in  claim 11 , wherein said parameters include altitude, roll, pitch, and yaw of said UAV system. 
     
     
         13 . The method as recited in  claim 11 , wherein said actual parameters are obtained from a plurality of sensors selected from a group consisting of gyroscopes, accelerometers, sonar, and pressure sensors. 
     
     
         14 . The method as recited in  claim 11 , wherein said correction values are a result of a difference between values of said desired and actual parameters after being subjected to a PID control loop. 
     
     
         15 . The method as recited in  claim 11 , wherein a first command mixer adds an altitude correction value and subtracts roll, pitch, and yaw correction values to send to a first one of the rotor controllers. 
     
     
         16 . The method as recited in  claim 15 , wherein a second command mixer adds said roll and altitude correction values but subtracts said pitch and yaw correction values to send to a second one of the rotor controllers. 
     
     
         17 . The method as recited in  claim 16 , wherein a third command mixer adds said pitch, yaw, and altitude correction values and disregards said roll correction value to send to a third one of the rotor controllers. 
     
     
         18 . The method as recited in  claim 17 , wherein said UAV system comprises:
 a main body having a front portion and a rear portion, wherein said main body is bifurcated by a line of symmetry;   first, second, and third similar arms extending radially from said main body, wherein said first and second arms extend from said front portion and are positioned relative to each other on opposite sides of said line of symmetry, and wherein said third arm extends from said rear portion along said line of symmetry; and   a single rotor positioned on each of said first, second, and third arms;   wherein said first one of the rotor controllers is configured to control rotational speed of said single rotor positioned on said first arm, wherein said second one of the rotor controllers is configured to control rotational speed of said single rotor positioned on said second arm, and wherein said third one of the rotor controllers is configured to control rotational speed of said single rotor positioned on said third arm.   
     
     
         19 . An unmanned aerial vehicle (“UAV”) consisting of first, second, and third single rotors, wherein the UAV further comprises:
 a main body having a front portion and a rear portion, wherein said main body is bifurcated by a line of symmetry; 
 first, second, and third similar arms extending radially from said main body, wherein said first and second arms extend from said front portion and are positioned an equal radial distance from said line of symmetry, and wherein said third arm extends from said rear portion along said line of symmetry; 
 wherein said first single rotor is positioned on said first arm; 
 wherein said second single rotor is positioned on said second arm; and 
 wherein said third single rotor is positioned on said third arm. 
 
     
     
         20 . The UAV as recited in  claim 19 , further comprising a fixed blade propeller attached to each rotor such that all three propellers are aligned on a common plane in a fixed manner.