Embodiments disclosed herein present a spring system for use in a torque dependent rotor assembly designed to operate in resonance, where changes in applied torque controls the blade pitch angle and ultimately the movements of a rotary wing aircraft. More specifically, the present invention relates to a spring system used in such a rotor assembly where the stiffness of an associated spring member is allowed to vary in response to the torque applied from a motor to the assembly.

An aerial vehicle is provided including rotor units connected to the aerial vehicle, and a control system configured to operate at least one of the rotor units. The rotor unit includes rotor blades, wherein each rotor blade includes a surface area, and wherein an asymmetric parameter is defined, at least in part, by the relationship between the surface areas of the rotor blades. The value of the asymmetric parameter is selected such that the operation of the rotor unit: (i) moves the rotor blades such that each rotor blade produces a respective vortex and (ii) the respective vortices cause the rotor unit to produce a sound output having an energy distribution defined, at least in part, by a set of frequencies, wherein the set of frequencies includes a fundamental frequency, one or more harmonic frequencies, and one or more non-harmonic frequencies having a respective strength greater than a threshold strength.

A propulsion system assembly includes a propeller, a motor configured to drive the propeller to rotate, and a locking mechanism configured to detachably lock the propeller to the motor. The propeller includes one of a first body and a second body. The motor includes another one of the first body and the second body. The locking mechanism includes a coupling member including a femoral position groove, a fastener configured to fix the coupling member to the second body, and a locking member configured to lock the first body to the coupling member and the second body. A bottom portion of the first body that contacts the coupling member includes a protruding rib configured to fit with the femoral position groove to restrain the first body from rotating relative to the coupling member.

An aircraft control system for an unmanned aircraft comprising a forward propulsion system comprising a forward thrust engine and a vertical propulsion system comprising a vertical thrust engine. The aircraft control system may include a controller comprising an input coupled to receive a velocity signal indicating a determined amount of forward velocity and being configured to generate a pitch angle command associated with the determined amount of forward velocity; a splitting block comprising an input to receive the pitch angle command and being configured to generate a second pitch angle command and a forward thrust engine throttle command based on a bounded pitch angle for the unmanned aircraft; and an output coupled to provide the second pitch angle command to the vertical propulsion system and the forward thrust engine throttle command to the forward propulsion system.

Methods and apparatus for performing repair operations using an unmanned aerial vehicle. The methods are enabled by equipping the UAV with tools for rapidly repairing a large structure or object (e.g., an aircraft or a wind turbine blade) that is not easily accessible to maintenance personnel. In accordance with various embodiments disclosed below, the unmanned aerial vehicle may be equipped with an easily attachable/removable module that includes an additive repair tool. The additive repair tool is configured to add material to a body of material. For example, the additive repair tool may be configured to apply a sealant or other coating material in liquid form to a damage site on a surface of a structure or object (e.g., by spraying liquid or launching liquid-filled capsules onto the surface). In alternative embodiments, the additive repair tool is configured to adhere a tape to the damage site.

A two degree-of-freedom motor includes a stator, a plurality of stator windings, a rotor, a shaft, a limited angle torque motor, and a spring. The stator has a main body and a plurality of stator poles. The stator windings are wound around the stator poles. The rotor is spaced apart from the stator and includes a plurality of magnets and is configured to rotate about a first rotational axis. The shaft is coupled to the rotor and is rotatable therewith and and has a shaft first end and a shaft second end. The limited angle torque motor is coupled to the shaft first end, and is operable to supply a torque that causes the shaft, the rotor, and the stator to rotate about a second rotational axis that is perpendicular to the first rotational axis. The spring is fixedly mounted and is coupled to the limited angle torque motor.

An unmanned aerial vehicle includes a main body and at least two rotor units configured to propel the unmanned aerial vehicle. The unmanned aerial vehicle includes at least two antenna units configured to receive a radio signal. The antenna units are located with respect to the main body such that the antenna units are assigned to different lateral sides of the main body. Further, a direction finding system is described.

A propulsion system assembly includes a propeller and a motor configured to drive the propeller to rotate. The propeller includes one of a first body and a second body. The motor comprises the other one of the first body and the second body. The propulsion system assembly also includes a locking mechanism configured to detachably connecting the first body and the second body. The locking mechanism includes a locking member and a position limiting lock catch. The locking member is configured to lock the first body and the second body. The locking member includes locking parts located at at least two sides of the locking member. When the locking parts of the locking member rotate to a locking position, the position limiting lock catch is mounted to a side of the locking parts, to restrain the locking member from rotating relative to the first body.

An innovative passive cooling solution with sealed UAV enclosure system allows heat from a semiconductor chip to be dissipated to the ambient environment through evaporation/condensation phase-change cooling and air cooling a heat sink such as a fin without any additional power consumption to operate cooling solution. One example of such a solution may include a pipe with a fin and a fluid. The pipe may include a wick structure along an inner surface of the pipe configured to allow the fluid to travel within the wick structure and to allow a vapor form of the fluid to exit the wick structure towards a center of the pipe.

A rotor assembly includes a motor, a propeller, and a connection assembly. The motor includes a stator and a rotator rotatable with respect to the stator. The connection assembly includes a locking member provided between the propeller and the rotator. The locking member is configured to rotate with respect to the rotator and the propeller to lock the propeller to the motor.