Five-Arm Coaxial Multirotor Layout for Single-Arm Failure Flight Stability
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Solution Overview
Problem
Conventional multi-rotor UAVs are destabilized and unable to maintain flight if one of their arms and/or associated components fail, due to their reliance on symmetry for lift, which increases structural weight, inertia, and cost when additional arms are added for redundancy.
Innovation Solution
A 5-armed multi-rotor UAV configuration with contra-rotating coaxial propellers, where each pair can be powered by a common or independent motor, allowing for throttling to maintain lift and tilt stability by adjusting the lift forces of remaining rotors to compensate for a failed arm, with an autopilot system detecting the failure and adjusting throttle settings to keep the center of lift aligned with the center of gravity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional arms are added to multi-rotor UAV for redundancy, then reliability is improved, but structural weight increases
Solution Approach 1:
The patent transitions from symmetric quadcopter configuration to asymmetric pentarotor configuration. The five arms are arranged in an asymmetric pattern where four arms form a quadrilateral structure and one arm extends centrally. This asymmetric layout enables the system to maintain flight stability with minimal redundancy (only one additional arm needed compared to quadcopter) while achieving fault tolerance capability, thus improving reliability without proportionally increasing structural weight.
Solution Approach 2:
The patent implements dynamic throttle control of individual rotors to compensate for arm failure. The control system dynamically adjusts the thrust of remaining functional rotors based on real-time feedback about the failed arm, allowing the UAV to maintain stable flight after single-arm failure. This dynamic adaptation enables the system to achieve reliability equivalent to hexarotor/octarotor configurations without adding the corresponding structural weight.
2Reliability
If additional arms are added to multi-rotor UAV for redundancy, then reliability is improved, but device complexity increases
Solution Approach 1:
The asymmetric pentarotor configuration achieves fault tolerance with only five arms instead of six or eight arms required by symmetric configurations. The asymmetric layout with one central arm and four peripheral arms creates inherent redundancy that enables single-arm failure compensation without requiring the full symmetry of hexarotor or octarotor designs, thus reducing device complexity while maintaining reliability.
Solution Approach 2:
The patent changes the fundamental parameter of arm configuration from symmetric (4, 6, or 8 arms) to asymmetric (5 arms with specific geometric arrangement). This parameter change enables the system to achieve the same reliability level with fewer components, reducing device complexity. The specific asymmetric geometry allows optimal distribution of thrust vectors for fault compensation.
3Reliability
If additional arms are added to multi-rotor UAV for redundancy, then reliability is improved, but cost increases
Solution Approach 1:
The asymmetric pentarotor design reduces manufacturing cost by requiring only five arms instead of six or eight arms. Each arm structure, motor, and propeller represents a significant cost component, so reducing the total number from 6-8 to 5 directly lowers material costs, assembly complexity, and overall manufacturing expense while still achieving single-arm failure redundancy.
Solution Approach 2:
The dynamic control system enables cost-effective reliability by using software-based throttle adjustment rather than hardware redundancy. Instead of adding more physical arms (which would increase cost), the system uses intelligent control algorithms to dynamically redistribute thrust among existing functional arms, achieving fault tolerance at minimal additional cost primarily related to control system computation.
4Reliability
If additional arms are added to multi-rotor UAV for redundancy, then reliability is improved, but thrust margin decreases
Solution Approach 1:
The asymmetric pentarotor configuration optimizes thrust margin by strategically positioning one central arm and four peripheral arms. This geometry allows the central arm to provide vertical lift while peripheral arms provide both lift and moment control. When one arm fails, the asymmetric layout enables more efficient redistribution of thrust vectors compared to symmetric configurations, preserving greater thrust margin for payload and overcoming the 20% lift force loss.
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 configuration enables the UAV to maintain stability and altitude with minimal arm redundancy, reducing the loss of lift force to 20% even if one arm fails, while keeping the number of arms to a minimum, thus balancing cost and size considerations.
Implementation Method 1
multi-rotor UAVs with four arms, each with one rotor... provide lift forces and movements in different directions
Implementation Method 2
Each rotor assembly is configured to carry a pair of contra rotating coaxial propellers
Data Source
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AI summary
The present disclosure provides a multi-rotor Aerial Vehicle comprising at least five arms. Pairs of coaxial contra rotating rotors/propellers are configured on each arm defining a polygon. In the event of failure of any one of the rotors/propellers, a control system incorporating an autopilot, shuts off corresponding contra rotating rotor/propeller of the pair to maintain yaw stability thereby rendering the corresponding arm non-functional; and adjusts throttles of the coaxial contra rotating rotors/propellers of remaining functional arms to maintain tilt and lift stability of the Aerial Vehicle.