Vectored Multicopter Thruster Control for Decoupled Flight Dynamics
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Solution Overview
Problem
Existing UAVs with thrust vectoring propulsion systems face limitations due to non-linear and highly coupled dynamics, which complicate control systems and restrict the degrees of motion, leading to inadequate stability and accuracy in data capture and maneuverability, especially in constrained spaces.
Innovation Solution
A method involving a decoupled mathematical model of multicopter dynamics allows for independent control of thruster variables, using orthogonal gimbals and a robust control algorithm like multiple-surface sliding control to adjust thrust amplitude and orientation, enabling precise thruster actuation and handling system uncertainties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If thrust vectoring propulsion units are used to improve maneuverability and stability, then the aircraft can achieve better positional stability and maneuverability, but the dynamics become non-linear and highly coupled, significantly increasing control system complexity
Solution Approach 1:
The control system is segmented into multiple independent control loops, each managing specific thruster parameters (thrust magnitude, pitch angle, roll angle) separately. This decomposition transforms the complex coupled control problem into manageable independent sub-problems, reducing overall control system complexity while maintaining stability.
Solution Approach 2:
The system employs dynamic control algorithms that adaptively adjust thruster parameters in real-time based on current flight conditions. This dynamic approach allows the control system to handle non-linear dynamics effectively by continuously optimizing control inputs, thereby managing complexity through adaptability rather than static complex control structures.
2Device complexity
If existing tilting rotor approaches are used with direct servo mounting, then the structure is simplified, but the degrees of motion are limited and cannot control the aircraft beyond designed angles
Solution Approach 1:
The control system extracts and independently manages each degree of freedom (thrust magnitude, pitch angle, roll angle) as separate controllable parameters. By taking out these control variables from the coupled system and controlling them independently, the system achieves enhanced adaptability and versatility without proportionally increasing structural complexity.
Solution Approach 2:
Each thruster assembly is designed with multi-functionality, capable of independent control in multiple degrees of freedom (both pitch and roll angles). This universal design allows the same thruster structure to perform multiple functions (thrust generation, pitch control, roll control), thereby increasing adaptability without requiring separate specialized mechanisms for each function.
3Adaptability or versatility
If prior art vectored thrusters with movable flaps and rotating nozzles are used, then thrust direction can be adjusted, but the movement is directly linked to thrust and rotational moments, limiting motor size selection
Solution Approach 1:
The control system segments the thrust vectoring function into independent control of pitch angle and roll angle, each managed by separate control loops. This segmentation decouples the control requirements from motor size constraints, allowing flexible motor selection since each degree of freedom is controlled independently rather than being directly linked to motor thrust and rotational moments.
Solution Approach 2:
The control system acts as an intermediary between the motors and the thrust vectoring mechanism. By introducing this intermediate control layer that independently manages pitch and roll angles, the system decouples the direct linkage between motor parameters and thrust direction, thereby removing constraints on motor size selection while maintaining precise thrust direction control.
4Ease of operation
If conventional PID controllers are used for thrust vectored UAVs, then the control implementation is simple, but the non-linear and highly coupled dynamics cannot be adequately controlled
Solution Approach 1:
The control system segments the complex non-linear control problem into multiple independent linear control loops, each managing specific thruster parameters. This segmentation allows the use of simple and reliable linear PID controllers for each independent loop, maintaining ease of operation while achieving adequate control of the overall non-linear system through the combined effect of multiple independent controllers.
Data Source
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AI summary
A method of operating a multicopter comprising a body and n thrusters, each thruster independently actuated to vector thrust angularly relative to the body about at least a first axis, the method comprising modelling dynamics of the multicoptor with a mathematical model comprising coupled, non-linear combinations of thruster variables, decoupling the mathematical model into linear combinations of thruster control variables, sensing at least one characteristic of multicopter dynamics, comparing the sensed data with corresponding target characteristic(s), computing adjustments in thruster control variables for reducing the difference between the sensed data and the target characteristic(s) according to a control algorithm, and actuating each thruster according to the computed thruster control variables to converge the muticopter towards the target characteristic(s), wherein the control algorithm is based on the decoupled mathematical model such that each thruster control variable can be adjusted independently.