eVTOL Control Allocation for Noise and Battery Balancing
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Solution Overview
Problem
Electric vertical take-off and landing (eVTOL) aircraft face challenges in control allocation due to their over-actuated systems, which complicate the distribution of control effort among multiple actuators, and also generate noise and uneven battery energy usage.
Innovation Solution
The proposed solution involves solving an optimization objective function that prioritizes meeting force and moment commands while modulating rotor acoustics and balancing battery pack energy as secondary objectives. This includes varying rotor speeds, minimizing propeller tip speed, and preferentially utilizing electric propulsion units powered by battery packs with greater charge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple electric propulsion units are used to provide vertical thrust and forward thrust, then the aircraft achieves VTOL capability and forward flight capability, but noise generation increases
Solution Approach 1:
The patent applies periodic action by modulating the speed of individual propellers in a cyclic pattern. During forward flight, propellers are selectively slowed or reversed in a rotating sequence, creating periodic variations in thrust that reduce overall noise while maintaining forward propulsion. This transforms continuous high-speed operation into a periodic pattern that spreads acoustic energy across different time intervals.
Solution Approach 2:
The patent implements local quality by allowing each propeller to operate at different speeds or reverse individually while others maintain forward thrust. This creates localized variations in thrust distribution across the aircraft's propulsion system, enabling noise reduction at specific locations and times while maintaining overall flight performance through coordinated control of multiple propellers.
2Use of energy by moving object
If multiple battery packs are used to power electric propulsion units, then energy capacity increases, but uneven energy consumption occurs
Solution Approach 1:
The patent implements feedback control by continuously monitoring the charge levels of multiple battery packs and using this information to dynamically adjust the power distribution to electric propulsion units. The control system receives feedback on battery states and automatically balances energy consumption by directing more power to battery packs with higher charge levels, preventing uneven discharge and maintaining stable energy distribution across the power system.
Solution Approach 2:
The patent applies dynamics by making the power distribution system adaptive and changeable based on real-time battery conditions. Instead of fixed power allocation, the system dynamically adjusts which propulsion units receive power from which battery packs, allowing the energy distribution strategy to evolve as battery charge levels change during flight operations.
3Measurement precision
If control effort is distributed among multiple actuators, then control precision improves, but control complexity increases
Solution Approach 1:
The patent implements universality by designing the control system to handle multiple functions through a unified control architecture. The same control system manages both vertical thrust control and forward flight control, as well as noise reduction and energy balancing, without requiring separate dedicated systems for each function. This multi-functional approach reduces overall system complexity while maintaining precise control across all operations.
Solution Approach 2:
The patent applies merging by combining multiple control objectives into a single integrated control framework. Instead of separately controlling thrust, noise, and energy distribution, the system merges these control tasks into one unified allocation algorithm that simultaneously optimizes all parameters, reducing the complexity that would arise from multiple independent control systems.
Data Source
AI summary
A method of controlling an electric aircraft that has a plurality of actuators that includes a plurality of electric propulsion units includes: receiving force and moment commands for the electric aircraft; determining control commands for the plurality of actuators based on the desired force and moment commands by solving an optimization problem that comprises a noise minimization term for minimizing noise generated by the electric propulsion units; and controlling the plurality of actuators according to the determined control commands to meet the force and moment commands for the electric aircraft.