Active Damping of Flexible Modes in UAV Airframes
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Solution Overview
Problem
Multi-propeller UAVs with flexible airframes experience reduced flight handling qualities due to undamped structural modes, which cannot be effectively stabilized by traditional methods without increasing weight and reducing flight time.
Innovation Solution
Active dampening of flexible modes is achieved by measuring linear acceleration and angular rate at locations proximate to the motors, using sensors and controllers to identify and modify motor operations to dampen these modes, allowing for direct observation and stabilization of flexible modes at the anti-nodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the rigidity of the multi-propeller UAV is increased to reduce flexible mode vibrations, then the flight handling qualities improve, but the weight of the vehicle increases which reduces available flight time
Solution Approach 1:
The patent changes the operational parameters of the motors to actively control and dampen flexible mode vibrations. By adjusting motor thrust and torque in real-time based on measured vibrations, the system achieves flight stability without requiring increased structural rigidity or additional weight.
Solution Approach 2:
The patent implements a feedback control system where sensors measure linear acceleration and angular rate, the controller identifies flexible modes based on these measurements, and then modifies motor operations to dampen the identified modes. This closed-loop feedback enables active vibration control without adding structural weight.
2Stability of the object's composition
If traditional stabilization methods are used to dampen flexible modes, then flight stability improves, but the system complexity increases and flight time is reduced
Solution Approach 1:
The patent uses the existing motor system to serve dual purposes: both propulsion and active vibration control. By modifying the operation of the same motors that provide thrust, the system dampens flexible modes without requiring separate dedicated damping mechanisms, thereby reducing overall system complexity.
Solution Approach 2:
The patent makes the motor system multi-functional by using it for both primary propulsion and secondary vibration damping. The same motors that generate thrust are also used to actively control flexible modes, eliminating the need for separate stabilization hardware and reducing system complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces stress and vibrations on the airframe, enabling improved flight performance and handling while maintaining a lightweight structure, thus enhancing the UAV's operational flight time and stability.
Implementation Method 1
The at least one sensor measures at least one of a linear acceleration and an angular rate at a location that is proximate to a motor of the UAV
Implementation Method 2
The at least one sensor measures at least one of a linear acceleration and an angular rate at a location that is proximate to a motor of the UAV
Implementation Method 3
modifying an operation of the motor based on at least one of the linear acceleration and angular rate to dampen the flexible mode
Data Source
AI summary
Embodiments described herein provide active dampening of flexible modes of a UAV during flight operations. During operation of a UAV having a flexible airframe, the thrust and/or torque of the motor(s) coupled to propellers can induce flexing in the airframe that reduces the flight performance of the UAV. Measurements of a linear acceleration and/or an angular rate at a location proximate to the motor are performed, and flexible modes in the airframe of the UAV are identified based on the measurements. An operation of the motor(s) is modified based on the measurements to dampen the flexible mode.