Tiltable Rotorcraft Control Allocation for Position-Attitude Decoupling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional rotorcrafts face challenges in complex scenarios due to strong coupling between position and attitude motions, nonlinearity, strong coupling in attitude channels, and uncertainty in model parameters, making it difficult to meet performance requirements for tasks like omni-directional maneuverability and attitude changes during hovering.
Innovation Solution
A method and system for controlling position and attitude separation in tiltable rotorcrafts, involving six-degree-of-freedom motion equations, control efficiency models, and capability prediction models, with subsystems for position, velocity, and attitude control, and a control allocation module to output actual control commands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional rotorcraft configuration is used, then the structure is simple and control is easy, but the coupling between position and attitude motions is strong, limiting performance in complex scenarios
Solution Approach 1:
The rotor assembly is made dynamically tiltable relative to the fuselage through a tilting mechanism, allowing the rotor plane to change its orientation. This dynamic adjustment capability enables the aircraft to decouple position and attitude control, achieving omnidirectional maneuverability and attitude changes during hovering, thus resolving the contradiction between simple structure and maneuverability.
2Adaptability or versatility
If a tiltable rotor mechanism is added to improve maneuverability, then position and attitude motions can be decoupled, but the control system design becomes more challenging due to strong nonlinearity and coupling
Solution Approach 1:
The control system is segmented into multiple independent modules: a capability prediction module that assesses control boundaries, a command correction module that adjusts commands within feasible ranges, and a control allocation module that distributes corrected commands to individual rotors. This modular segmentation manages the complexity introduced by the tiltable rotor mechanism while maintaining omnidirectional maneuverability.
Solution Approach 2:
The capability prediction module performs preliminary assessment of control boundaries and command feasibility before the actual control action is executed. By predicting whether desired commands are within the control capability range in advance, the system can pre-correct commands to avoid saturation and instability, thus managing control complexity while preserving maneuverability.
3Speed
If commands are executed without correction, then the response is fast, but commands beyond control capacity range cause controller instability
Solution Approach 1:
The command correction module implements feedback by continuously monitoring whether desired commands are within the predicted control capability range. When commands exceed the feasible range, the module corrects them to the boundary of the capability range, preventing control saturation and instability while maintaining fast response through minimal necessary correction.
Solution Approach 2:
Command correction is performed preliminarily before control signals are sent to the actuators. By assessing and correcting commands in advance based on predicted capability boundaries, the system ensures stability is maintained without sacrificing response speed, as the correction occurs in the computational domain rather than delaying physical actuation.
Data Source
AI summary
A method and system for controlling position and attitude separation of a tiltable rotorcraft is provided, including a capability prediction module, a position control subsystem, a velocity control subsystem, an attitude angle control subsystem, an angular rate control subsystem, a control allocation module, and a tiltable rotorcraft. After expected position and attitude commands are corrected by the capability prediction module, expected force and torque commands are output by various control subsystems, and after receiving the force and torque commands, the control allocation module is further configured to calculate actual control commands of the aircraft, such as a tilt angle of a rotor assembly and a rotor speed, thus controlling the tiltable rotorcraft to perform the tracking of the expected position and attitude commands.