Tethered Quadcopter Simulation

This repository contains MATLAB code for simulating the nonlinear control of a quadcopter tethered to a ground-based winder. The system uses a backstepping control technique and simulates the UAV moving through predefined waypoints while incorporating the dynamics of a tether.

Features

• Quadcopter Simulation: Models the dynamics of a quadcopter including its position, orientation, and motion.
• Tether Dynamics: Simulates the behavior of the tether using catenary and spring-damper models to capture realistic tether motion and wiggling effects.
• Nonlinear Control: Implements a backstepping control method to ensure stability and waypoint tracking.
• Customizable Parameters: Provides options to modify quadcopter, tether, and winder characteristics.
• 3D Visualization: Animates the quadcopter's trajectory along with tether dynamics.

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Getting Started

Prerequisites

• MATLAB (R2020b or later is recommended)
• MATLAB's ODE solver (e.g., ode45)

Installation

1. Clone this repository:

   git clone https://github.com/AUVSL/TUAV_system_control.git
   cd TUAV_system_control

2. Open MATLAB and set the cloned directory as your working folder.

Usage

Running the Simulation

1. Open the main.m script.
2. Modify the parameters in the main.m file as needed:

• Quadcopter parameters: Mass, moments of inertia, etc.
• Tether parameters: Density, cross-sectional area, initial tension, etc.
• Winder parameters: Moment of inertia, radius, etc.
• Controller gains: Adjust the gains (k1, k2, ..., k14) for tuning.
• Waypoints: Define the UAV's desired trajectory.

3. Run the script by typing:

  main

4. Watch the 3D animation of the quadcopter and tether in real-time.

Files Overview

• main.m: Main script that initializes parameters, solves the system's dynamics using ode45, and visualizes the simulation.
• draw_drone.m: Helper function to visualize the quadcopter in 3D with its propellers and body axes.
• get_rotation.m: Calculates the rotation matrix for transforming the quadcopter's orientation.
• dynamics.m: Defines the system's ordinary differential equations (ODEs) for the quadcopter, tether, and winder.
• cableDynamics.m: Simulates the internal dynamics of the tether using a spring-damper model.

Output

Visualization

• Quadcopter Trajectory: Displays the UAV's movement and tether dynamics in a 3D plot.
• Waypoints: Shows predefined positions that the quadcopter tracks during the simulation.
• Trail: Illustrates the path followed by the UAV.

Data

Simulation results for position, orientation, tether length, and other state variables are available in the workspace for post-processing.

Customization

• Modify the control gains (k1 to k14) in the main.m script for different stability and tracking behaviors.
• Change the tether parameters (e.g., length, density) to experiment with various configurations.
• Adjust the number of masses (n) in the tether model for finer resolution or faster simulation.

Limitations

• The simulation assumes ideal environmental conditions with simplified wind disturbances.
• Cable dynamics are approximated using a spring-damper model and may not fully capture real-world tether behavior.

Acknowledgments

If you find this useful, consider citing our paper: