UAV Pitch-Thrust Control for Stable Hover Across Airspeeds
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Solution Overview
Problem
Existing hybrid multirotor aircraft control systems face inefficiencies in maintaining stable hovering flight across a wide range of air speeds due to the separation of VTOL and forward propulsion control systems, leading to increased drag and reduced control efficiency.
Innovation Solution
Combining pitch angle control of the aircraft with forward thrust control of the main fixed-wing engine, using a controller to generate pitch angle and throttle commands that balance the aircraft's pitch angle and forward thrust, allowing for level flight across varying air speeds by abstracting the forward thrust control into pseudo-control components for the VTOL and forward propulsion systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If pitch angle control and forward thrust control are separated into fixed wing flight modes, then VTOL operations can be controlled using typical multirotor methods, but adequate control during hovering modes with non-trivial airspeed is not provided
Solution Approach 1:
The patent merges pitch angle control and forward thrust control into a unified control system that simultaneously manages both VTOL and forward propulsion systems. The controller receives a single pitch angle command and automatically distributes it between the VTOL rotors and forward thrust rotor, enabling seamless operation across hovering, transition, and forward flight modes without requiring separate control schemes for each mode.
2Stability of the object's composition
If a large pitch up command is combined with a large forward thrust to achieve stable position control, then position stability is improved, but both systems work harder than desired reducing efficiency
Solution Approach 1:
The control system dynamically adjusts the distribution of pitch angle commands between the VTOL propulsion system and forward propulsion system based on real-time flight conditions. The controller continuously optimizes the split of control authority to achieve stable position control while minimizing the workload on both propulsion systems, preventing unnecessary energy consumption and system stress.
3Stability of the object's composition
If the VTOL propulsion system provides additional thrust to compensate for negative angle of attack during forward flight, then altitude maintenance is improved, but further drag is added to the aircraft
Solution Approach 1:
The control system uses feedback from flight conditions to dynamically adjust the coordination between pitch angle control and forward thrust control. When the aircraft experiences negative angle of attack during forward flight, the controller detects this condition and automatically adjusts the thrust distribution to maintain altitude while minimizing additional drag by optimizing the contribution of each propulsion system.
Data Source
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AI summary
An unmanned aircraft includes a forward propulsion system comprising one or more forward thrust engines and one or more corresponding rotors coupled to the forward thrust engines; a vertical propulsion system comprising one or more vertical thrust engines and one or more corresponding rotors coupled to the vertical thrust engines; and a pitch angle and throttle control system, comprising a processor configured to receive a first pitch angle command; and generate a second pitch angle command and a forward thrust engine throttle command based on a bounded pitch angle for the aircraft.