Quadrotor Attitude Planning for Unwinding-Free Trajectory Tracking
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Solution Overview
Problem
Existing quadrotor UAV control technologies face challenges such as lockup at particular positions, redundant calculations, and unwinding phenomena due to Euler angle-based, rotation matrix-based, and quaternion-based attitude controllers, which hinder global stabilization and robustness.
Innovation Solution
A method and system that utilize a quaternion-based dynamic model with a Rodrigues parameter to design a smooth attitude planner, incorporating a fictitious force control to convert the underactuated quadrotor into a fully-actuated form, and employ a backstepping method for continuous feedback torque control, combining outer-loop position and inner-loop attitude control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If Euler angle-based attitude controller is used, then the controller has simple design and intuitive physical significance, but it causes lockup problem at particular position and cannot realize global control
Solution Approach 1:
The patent transforms the attitude description from Euler angles to quaternions, changing the mathematical parameters used to represent orientation. This parameter transformation eliminates the singularity problem inherent in Euler angles while maintaining computational feasibility through the use of unit quaternions and their differential equations.
2Reliability
If rotation matrix-based attitude controller is used, then it can overcome the lockup problem, but it has redundant calculation and high storage cost
Solution Approach 1:
The patent extracts the essential orientation information from the rotation matrix by using quaternions, which represent the same rotational information with fewer parameters (4 vs 9). This extraction eliminates the redundant calculations and storage requirements while preserving the ability to represent any orientation without singularity.
3Device complexity
If quaternion-based continuous controller is used, then it overcomes lockup and redundant calculation problems, but it causes unwinding phenomenon
Solution Approach 1:
The patent introduces a smooth attitude planner that dynamically adjusts the quaternion evolution to prevent unnecessary 360-degree rotations. The planner uses differential equations to ensure the quaternion transitions smoothly between orientations without completing full rotations, thereby preventing the unwinding phenomenon while maintaining the computational efficiency of quaternion representation.
4Reliability
If hybrid hysteretic control is introduced to overcome unwinding problem, then the quaternion-based controller can be realized, but it loses desirable robustness and becomes difficult to implement
Solution Approach 1:
The patent maintains continuous and smooth control actions through the attitude planner that uses differential equations to guide quaternion evolution. This continuous approach avoids the discontinuous switching inherent in hybrid hysteretic control, preserving system robustness while preventing unwinding through smooth, predictable control transitions.
Data Source
AI summary
Provided are an attitude planner-containing trajectory tracking control method and system for a quadrotor unmanned aerial vehicle (UAV). The attitude planner-containing trajectory tracking control method for a quadrotor UAV includes: acquiring a barycentric coordinate, a yaw angle, a pitch angle, a roll angle, a linear velocity along a coordinate direction, and an angular velocity of a corresponding turning angle of the quadrotor UAV in real time; calculating a quaternion-based quadrotor UAV dynamic model; constructing a smooth attitude planner; calculating an attitude error dynamic system model of the quadrotor UAV according to a planned attitude angular velocity with a Rodrigues parameter; in combination with a position dynamic system model and the attitude error dynamic system model based on the Rodrigues parameter, constructing an outer-loop trajectory tracking control module and an inner-loop attitude control module with a hierarchical control technology; obtaining an attitude planner-containing trajectory tracking control result for the quadrotor UAV.