Velocity-Free Attitude Control of Quadrotors: A Nonlinear Negative Imaginary Approach

Area of Science:

• Robotics and Control Systems
• Nonlinear Control Theory

Background:

• Quadrotor attitude control traditionally relies on angular velocity measurements or complex observers.
• Existing methods can be sensitive to modeling uncertainties and external disturbances.

Purpose of the Study:

• To develop a quadrotor attitude control strategy that does not require angular velocity information.
• To ensure robust asymptotic stability of the quadrotor's attitude.

Main Methods:

• Utilizing recent stability results for nonlinear negative imaginary (NMI) systems.
• Implementing an inner-outer loop control structure.
• Establishing the NMI property of the quadrotor's rotational subsystem.
• Synthesizing a strictly negative imaginary controller.

Main Results:

• Demonstrated the nonlinear negative imaginary property of the quadrotor rotational subsystem.
• Successfully synthesized a strictly negative imaginary controller.
• Simulation results indicate robust asymptotic stability of attitude control.
• The approach is effective despite modeling uncertainties and external disturbances.

Conclusions:

• The proposed attitude control method offers a robust and sensor-independent solution for quadrotors.
• Nonlinear negative imaginary control theory provides a powerful framework for enhancing quadrotor stability.
• This approach advances quadrotor control by removing reliance on angular velocity measurements.