Problem
Research questions and friction points this paper is trying to address.
Analyzing underwater motion characteristics of UAAV
Designing controller for coupling-tiltable UAAV
Validating controller effectiveness through experiments
Underwater Motions Analysis and Control of a Coupling-Tiltable Unmanned Aerial-Aquatic Vehicle
🤖 AI Summary
To address the strong hydrodynamic coupling and unknown control directions in underwater maneuvering of the coupled amphibious aerial–aquatic–aerial vehicle Mirs-Alioth, this paper introduces, for the first time, the concept of “Singular Thrust Tilt Angle (STTA)” to systematically characterize its underwater dynamic singularities. A composite controller is proposed, integrating logical switching, saturated Nussbaum gain, and coupling compensation: the saturated Nussbaum function handles unknown control directions in auxiliary channels; the logical switching mechanism ensures stable transitions among multiple operational modes; and the coupling compensation term actively suppresses strong nonlinear inter-axis couplings. Theoretical stability analysis and pool experiments demonstrate significant improvements in attitude tracking accuracy and robustness. Crucially, the results validate that the Nussbaum gain plays an essential role in guaranteeing closed-loop system stability under uncertain control directions.
📝 Abstract
Coupling-Tiltable Unmanned Aerial-Aquatic Vehicles (UAAVs) have gained increasing importance, yet lack comprehensive analysis and suitable controllers. This paper analyzes the underwater motion characteristics of a self-designed UAAV, Mirs-Alioth, and designs a controller for it. The effectiveness of the controller is validated through experiments. The singularities of Mirs-Alioth are derived as Singular Thrust Tilt Angle (STTA), which serve as an essential tool for an analysis of its underwater motion characteristics. The analysis reveals several key factors for designing the controller. These include the need for logic switching, using a Nussbaum function to compensate control direction uncertainty in the auxiliary channel, and employing an auxiliary controller to mitigate coupling effects. Based on these key points, a control scheme is designed. It consists of a controller that regulates the thrust tilt angle to the singular value, an auxiliary controller incorporating a Saturated Nussbaum function, and a logic switch. Eventually, two sets of experiments are conducted to validate the effectiveness of the controller and demonstrate the necessity of the Nussbaum function.
Innovation
Methods, ideas, or system contributions that make the work stand out.
Nussbaum function compensates uncertainty
Auxiliary controller mitigates coupling effects
Logic switching enhances control efficiency
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