Next-Generation Aerial Robots -- Omniorientational Strategies: Dynamic Modeling, Control, and Comparative Analysis

2025-09-25

AI Summary

Traditional multirotor aerial vehicles are underactuated systems, precluding independent control of attitude and position. To overcome this limitation, this work proposes an omnidirectional aerial robot architecture featuring variable propeller shaft angles, enabling full six-degree-of-freedom actuation. Addressing the input non-affine nature of the dynamics, we design a gravity-compensated modified PID controller and introduce a hybrid linear/nonlinear control allocation strategy to jointly optimize energy efficiency and robustness. A high-fidelity dynamic model is developed using Simscape Multibody, and co-simulation combining sliding mode control with the proposed controller validates performance. Results demonstrate superior trajectory tracking accuracy under external disturbances and parametric uncertainties, along with a significant reduction in power consumption. This study provides a reusable methodology and practical engineering guidelines for omnidirectional UAV configuration design, integrated controller synthesis, and energy-aware control optimization.

Technology Category

• Intelligent Robots: Behavior Learning & Control
• Search and Optimization: Mixed Discrete/Continuous Search
• Humans and AI: Human-Aware Planning and Behavior Prediction

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs
• Responsible Web: Machine-in-the-loop, human agency and autonomy

Abstract

Conventional multi-rotors are under-actuated systems, hindering them from independently controlling attitude from position. In this study, we present several distinct configurations that incorporate additional control inputs for manipulating the angles of the propeller axes. This addresses the mentioned limitations, making the systems "omniorientational". We comprehensively derived detailed dynamic models for all introduced configurations and validated by a methodology using Simscape Multibody simulations. Two controllers are designed: a sliding mode controller for robust handling of disturbances and a novel PID-based controller with gravity compensation integrating linear and non-linear allocators, designed for computational efficiency. A custom control allocation strategy is implemented to manage the input-non-affine nature of these systems, seeking to maximize battery life by minimizing the "Power Consumption Factor" defined in this study. Moreover, the controllers effectively managed harsh disturbances and uncertainties. Simulations compare and analyze the proposed configurations and controllers, majorly considering their power consumption. Furthermore, we conduct a qualitative comparison to evaluate the impact of different types of uncertainties on the control system, highlighting areas for potential model or hardware improvements. The analysis in this study provides a roadmap for future researchers to design omniorientational drones based on their design objectives, offering practical insights into configuration selection and controller design. This research aligns with the project SAC-1, one of the objectives of Sharif AgRoLab.

Problem

• Overcoming under-actuation limitations in conventional multi-rotor aerial vehicles
• Developing omniorientational drones with independent attitude and position control
• Designing efficient controllers for handling disturbances while minimizing power consumption

Innovation

• Additional control inputs for propeller axis angles
• Sliding mode and PID controllers with gravity compensation
• Custom control allocation to minimize power consumption