Odd-Rotor Multi-rotor Aircraft Flight Control
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Solution Overview
Problem
Conventional multi-rotor VTOL designs, such as quadcopters, face scalability issues due to complex and coupled flight control systems, which limit control bandwidth and make it difficult to manage movements and moments as vehicle size increases, especially when trying to balance torque and generate lift, thrust, and yaw forces.
Innovation Solution
The use of an odd number of rotors, with a smaller auxiliary rotor positioned forward and additional thrust rotors at a 90-degree angle to the main rotors, decouples movement controls, reducing unbalanced torque and allowing for more efficient control of the aircraft by using a combination of fixed and variable pitch rotors to manage lift, thrust, pitch, roll, and yaw.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a quadcopter design with four rotors is used, then inherent stability and ease of control are improved, but scalability and control bandwidth deteriorate as vehicle size increases
Solution Approach 1:
The flight control system is segmented into independent control channels for different rotor groups. The five rotors are divided into functional groups (main lift rotors, auxiliary rotor, thrust rotors) that can be controlled independently, allowing the system to maintain stability while scaling to different vehicle sizes and configurations.
Solution Approach 2:
The control system dynamically adjusts rotor speeds based on real-time flight conditions and vehicle configuration. The auxiliary rotor's speed is dynamically modulated to counterbalance torque variations, and thrust rotors dynamically provide yaw control, enabling the system to adapt to different flight regimes and vehicle sizes.
2Force
If traditional rotor configuration is used, then lift generation is improved, but torque balance and control complexity worsen
Solution Approach 1:
The rotor configuration uses an asymmetric layout with five rotors instead of the traditional symmetric four-rotor quadcopter. The auxiliary rotor is positioned and sized differently from the main rotors, creating an asymmetric torque distribution that requires active compensation through differential speed control, thereby simplifying the overall control architecture.
Solution Approach 2:
The auxiliary rotor serves multiple functions: it provides lift generation like the main rotors, counterbalances torque from other rotors, and enables pitch control. The thrust rotors provide both thrust for forward motion and yaw control. This multi-functionality reduces the number of dedicated components needed and simplifies the control system.
3Measurement precision
If more rotors are added to improve control precision, then flight control precision is improved, but system complexity and torque management worsen
Solution Approach 1:
The control functions for lift, torque balancing, and pitch control are merged into the operation of the auxiliary rotor, while thrust and yaw control are merged into the thrust rotors. This consolidation reduces the number of independently controlled elements compared to having separate dedicated rotors for each function, thereby maintaining precision while reducing 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 configuration improves scalability and flight control efficiency by reducing unbalanced torque and pitch coupling, allowing for more precise control and stable flight characteristics, even as vehicle size increases, by leveraging the smaller auxiliary rotor and strategically positioned thrust rotors for yaw and thrust control.
Implementation Method 1
Typical VTOL systems have multiple fixed-pitch rotors that work to produce the forces necessary for flight; which include lift, thrust, and side movement
Implementation Method 2
The configuration of rotors or propellers can also be used to provide thrust forces at speeds that are generally below those needed for a fixed winged aircraft
Implementation Method 3
The forward thrust in a VTOL is typically managed by the control or change in rotational speed (RPM) of the various rotors. This can be done by varying the speed of one or more rotors to drive the direction of the vehicle by changing the thrust generated by the rotors
Data Source
AI summary
A system and method for controlling a multi-rotor aircraft that implements the unconventional use of an odd number of rotors. The odd or auxiliary rotor is designed to be smaller in diameter than the remaining main rotors and accordingly generates a smaller unbalanced torque and pitch on the aircraft. Additional configurations implement the use of smaller thrust rotors that can be used to generate thrust as well as control yaw and thus counteract any remaining unbalanced torque from the odd auxiliary rotor.