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Design and Control of a Coaxial Dual-rotor Reconfigurable Tailsitter UAV Based on Swashplateless Mechanism

Jinfeng Liang, Haocheng Guo, Ximin Lyu

TL;DR

This work addresses wind sensitivity and efficiency trade-offs in tailsitter VTOL UAVs by introducing the Dual-rotor Reconfigurable Tailsitter (DART). It combines wing retractability to reduce wind exposure, a coaxial heterogeneous dual-rotor propulsion layout, and an optimized swashplateless mechanism (SPLM) to enable stable multi-rotor control with only two actuators. Key contributions include a 66.2% reduction in frontal area via wing retraction, up to 29.2% average power savings from CHD propulsion, and a 62.9% reduction in SPLM torque vibration with a 6 dB/Hz vibration PSD improvement, validated through wind tests, efficiency benchmarks, and comprehensive transition flights. The results demonstrate robust wind disturbance rejection, efficient cruise performance, and reliable mode transition up to 15.6 m/s, with implications for practical, wing-reconfigurable VTOL UAVs in uncertain environments.

Abstract

The tailsitter vertical takeoff and landing (VTOL) UAV is widely used due to its lower dead weight, which eliminates the actuators and mechanisms for tilting. However, the tailsitter UAV is susceptible to wind disturbances in multi-rotor mode, as it exposes a large frontal fuselage area. To address this issue, our tailsitter UAV features a reconfigurable wing design, allowing wings to retract in multi-rotor mode and extend in fixed- wing mode. Considering power efficiency, we design a coaxial heterogeneous dual-rotor configuration, which significantly re- duces the total power consumption. To reduce structural weight and simplify structural complexity, we employ a swashplateless mechanism with an improved design to control pitch and roll in multi-rotor mode. We optimize the structure of the swashplateless mechanism by adding flapping hinges, which reduces vibration during cyclic acceleration and deceleration. Finally, we perform comprehensive transition flight tests to validate stable flight performance across the entire flight envelope of the tailsitter UAV.

Design and Control of a Coaxial Dual-rotor Reconfigurable Tailsitter UAV Based on Swashplateless Mechanism

TL;DR

This work addresses wind sensitivity and efficiency trade-offs in tailsitter VTOL UAVs by introducing the Dual-rotor Reconfigurable Tailsitter (DART). It combines wing retractability to reduce wind exposure, a coaxial heterogeneous dual-rotor propulsion layout, and an optimized swashplateless mechanism (SPLM) to enable stable multi-rotor control with only two actuators. Key contributions include a 66.2% reduction in frontal area via wing retraction, up to 29.2% average power savings from CHD propulsion, and a 62.9% reduction in SPLM torque vibration with a 6 dB/Hz vibration PSD improvement, validated through wind tests, efficiency benchmarks, and comprehensive transition flights. The results demonstrate robust wind disturbance rejection, efficient cruise performance, and reliable mode transition up to 15.6 m/s, with implications for practical, wing-reconfigurable VTOL UAVs in uncertain environments.

Abstract

The tailsitter vertical takeoff and landing (VTOL) UAV is widely used due to its lower dead weight, which eliminates the actuators and mechanisms for tilting. However, the tailsitter UAV is susceptible to wind disturbances in multi-rotor mode, as it exposes a large frontal fuselage area. To address this issue, our tailsitter UAV features a reconfigurable wing design, allowing wings to retract in multi-rotor mode and extend in fixed- wing mode. Considering power efficiency, we design a coaxial heterogeneous dual-rotor configuration, which significantly re- duces the total power consumption. To reduce structural weight and simplify structural complexity, we employ a swashplateless mechanism with an improved design to control pitch and roll in multi-rotor mode. We optimize the structure of the swashplateless mechanism by adding flapping hinges, which reduces vibration during cyclic acceleration and deceleration. Finally, we perform comprehensive transition flight tests to validate stable flight performance across the entire flight envelope of the tailsitter UAV.

Paper Structure

This paper contains 18 sections, 16 equations, 12 figures, 1 table.

Table of Contents

  1. INTRODUCTION
  2. RELATED WORK
  3. Propulsion Efficiency Optimization
  4. SPLM
  5. HARDWARE DESIGN
  6. UAV Configuration
  7. Aerodynamic Design
  8. Optimized SPLM
  9. Reconfigurable Wing Design
  10. CONTROL
  11. Control System Overview
  12. Mixer design
  13. EXPERIMENTS AND RESULTS
  14. Wind Disturbance Rejection Verification
  15. CHD Efficiency Verification
  16. ...and 3 more sections

Figures (12)

  • Figure 1: Transition and reconfiguration process of DART: a coaxial dual-rotor reconfigurable tailsitter UAV
  • Figure 2: (a) Definition of coordinate Frames for SPLM and UAV (Top View). (b) The components of optimized SPLM.
  • Figure 3: Layout of the DART
  • Figure 4: Lever model for tandem wings aircraft
  • Figure 5: Curve of lift and moment versus AoA
  • ...and 7 more figures