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Full Attitude Intelligent Controller Design of a Heliquad under Complete Failure of an Actuator

Eeshan Kulkarni, Suresh Sundaram

TL;DR

The results clearly indicate that the Heliquad with an intelligent controller provides necessary tracking performance even under a complete loss of one actuator.

Abstract

In this paper, we design a reliable Heliquad and develop an intelligent controller to handle one actuators complete failure. Heliquad is a multi-copter similar to Quadcopter, with four actuators diagonally symmetric from the center. Each actuator has two control inputs; the first input changes the propeller blades collective pitch (also called variable pitch), and the other input changes the rotation speed. For reliable operation and high torque characteristic requirement for yaw control, a cambered airfoil is used to design propeller blades. A neural network-based control allocation is designed to provide complete control authority even under a complete loss of one actuator. Nonlinear quaternion based outer loop position control, with proportional-derivative inner loop for attitude control and neural network-based control allocation is used in controller design. The proposed controller and Heliquad designs performance is evaluated using a software-in-loop simulation to track the position reference command under failure. The results clearly indicate that the Heliquad with an intelligent controller provides necessary tracking performance even under a complete loss of one actuator.

Full Attitude Intelligent Controller Design of a Heliquad under Complete Failure of an Actuator

TL;DR

The results clearly indicate that the Heliquad with an intelligent controller provides necessary tracking performance even under a complete loss of one actuator.

Abstract

In this paper, we design a reliable Heliquad and develop an intelligent controller to handle one actuators complete failure. Heliquad is a multi-copter similar to Quadcopter, with four actuators diagonally symmetric from the center. Each actuator has two control inputs; the first input changes the propeller blades collective pitch (also called variable pitch), and the other input changes the rotation speed. For reliable operation and high torque characteristic requirement for yaw control, a cambered airfoil is used to design propeller blades. A neural network-based control allocation is designed to provide complete control authority even under a complete loss of one actuator. Nonlinear quaternion based outer loop position control, with proportional-derivative inner loop for attitude control and neural network-based control allocation is used in controller design. The proposed controller and Heliquad designs performance is evaluated using a software-in-loop simulation to track the position reference command under failure. The results clearly indicate that the Heliquad with an intelligent controller provides necessary tracking performance even under a complete loss of one actuator.

Paper Structure

This paper contains 19 sections, 2 theorems, 43 equations, 25 figures, 2 tables.

Table of Contents

  1. INTRODUCTION
  2. HELI-QUAD DESIGN
  3. Definition of Complete Failure
  4. Static Equilibrium with Three Operating Actuators
  5. Propeller Aerodynamics Model
  6. Heli-quad Propeller Design
  7. Experimental Bench Test Results
  8. INTELLIGENT FAULT-TOLERANT CONTROLLER DESIGN FOR A HELI-QUAD
  9. Controllability analysis
  10. Linear controllability analysis
  11. Outer and Inner loop controllers
  12. Reconfigurable fault tolerant control allocation scheme
  13. Calculation of the thrust and torque for individual rotor
  14. Calculation of actuator commands
  15. Performance Evaluation of the Fault-Tolerant Heli-quad Controller
  16. ...and 4 more sections

Key Result

Theorem 1

Consider a system $\dot{x}=h(x, u)$. Suppose there exist a scalar function $V(x): \mathbb{R}^{n} \rightarrow \mathbb{R}$, and a vector function $U(x): \mathbb{R}^{n} \rightarrow \mathbb{R}^{m}$ in $C^{1}$ such that (a) $V(x)=0$ if and only if $x=0$, and $V(x)>0$ otherwise; (b) $\lim _{\mid x \| \rig

Figures (25)

  • Figure 1: Frame of references along with propeller rotation direction (subscript of $\omega$ is actuator number). The $4$th actuator is failed completely.
  • Figure 2: Airfoil section located at distance $r$ from axis of rotation (left), flow diagram for that airfoil section (right), $\phi$ is the pitch angle of propeller, $V_i$ is constant axial induced velocity, $V$ is the total velocity as seen by airfoil section, $\theta$ is flow angle and $\alpha$ is angle of attack of airfoil section.
  • Figure 3: (a) Airfoil shape comparison. (b) Lift characteristic comparison. (c) Lift vs Drag coefficient comparison. Airfoils are analysed at Reynolds number of 100,000 (Source : Xfoil code)
  • Figure 4: Geometry of the propeller blade.
  • Figure 5: Contour lines of thrust and torque produced by single actuator, propeller pitch angle and motor RPM can move anywhere in this plane. Cross represents equilibrium control input for actuator 2 when 4$^{th}$ one fails, solid circle represents the control input for actuator 1 and 3. Assumed mass of Heli-quad is 600 grams. Roll control is possible because of variable pitch actuation which can generate negative thrust.
  • ...and 20 more figures

Theorems & Definitions (3)

  • Definition 1: kim
  • Theorem 1: kim
  • Corollary 1.1: kim