1. Uwe Fechner
  2. FreeKiteSim

Overview

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Free Kite Power System Simulator

This project aims at the development of a free kite-power system simulator for educational purposes.

Intended use:

  1. Provide a learning environment for students who are studying airborne wind energy.
  2. Training of kite pilots and winch operators. In this case kite and winch are operated with joysticks.
  3. Development and test of automatic control software for kite-power systems.

This software is published under the LGPL license.

If you have any suggestions and fixes to improve this software please write a posting on https://groups.google.com/forum/#!forum/free-kitesim .

Installation

The installation was tested on Ubuntu 12.04 and 14.04, but it should work on any modern 64 bit Linux computer.

The installation uses the python package manager conda. There are two available versions of conda, we usually use Miniconda as it is the smallest package and can be adjusted to your needs with the least overhead. Four dependencies will NOT be installed through conda, namely gfortran, freeglut3, git and unxz so these will need to be installed on the system. For ubuntu just run:

sudo apt-get install gfortran freeglut3 git xz-utils

Next you'll need to install the conda packages. For convenience we created a meta-packages which should install all the needed packages. This can be found on our channel on Binstar:

conda create -n freekitesim -c https://conda.binstar.org/ufechner -c https://conda.binstar.org/mutirri freekitesim

This will create a new environment and install all dependencies into it. And that should be all that is needed to run the simulation and player. Before running you have to enable the environment however:

source activate freekitesim

If you would like to develop the simulation we can recommend installing the package spyder_full:

conda install -n freekitesim -c https://conda.binstar.org/ufechner spyder_full

This will install spyder with all addons and options set for developing as we use it.

For some packages it is important that the version stays the same even when updating the environment. These packages therefore need to be pinned to a specific version. To do that cd into your environment folder, here it is assumed that miniconda is in the home folder and the environment is called freekitesim, and run the following commands in your terminal:

cd ~/miniconda/envs/freekitesim/conda-meta
echo 'numba 0.18.2' >> pinned
echo 'boost 1.55.0' >> pinned
echo 'pandas 0.14.1' >> pinned

If you questions regarding the installation or the usage, please write a posting on https://groups.google.com/forum/#!forum/free-kitesim .

How to use

The Software can be used in two different modes at this point.

  • The log-file viewer allows to replay test-flights by reading the recorded data and showing the movement in a 3D animation
  • The dynamic simulator offers the user the possibility to tweak parameters and test control software with a four-point kite model

The two different programs can be run with the executable scripts kitesim.sh and kiteplayer.sh. Obviously the former runs the simulation and the other the log-file viewer.

How to use the log-file viewer

  1. Unpack compressed log files with the commands:

    cd ~/00PythonSoftware/FreeKiteSim/00_results
    unxz *.xz
    
  2. Run the 3D viewer and the GUI-based log file player:

    cd ~/00PythonSoftware/FreeKiteSim
    ./kiteplayer.sh
    
  3. Rearange the windows so that they do not overlap. Select a log file in the combobox on the left and press play.

Please look also at the FreeKiteSim manual. A .pdf version of the documentation can be created with the following commands:

cd doc
./make.sh

How to use the dynamic simulator

The dynamic simulation is done with the RADAU solver from the ASSIMULO solver suite. One simple example can be found in the example folder.

The following files belong to the dynamic simulator:

  • Timer.py (timer class, used for benchmarking)
  • linalg_3d.py (fast 3D linear algebra routines)
  • KCU_Sim.py (simulator for the kite control unit)
  • KPS4P_v2.py (Python version of the 4-point kite model)
  • WinchModel.py (model of the 20 kW winch of TU Delft)
  • Kite_4_point.py (script to construct the initial positions of the kite particles)
  • RTSim.py (simulator core, based on Assimulo and using the RADAU solver)
  • KiteViewer3.py (extended version of the 3D kite viewer)
  • Logger.py (Saves the simulation data to a log file if wanted)

To run the simulation:

  1. connect a joystick, e.g. Logitech Gamepad F310 or Logitech Extreme 3D Pro (prefered)

  2. open a terminal and enter:

    cd ~/00PythonSoftware/FreeKiteSim/
    ./kitesim.sh
    
  3. wait until the message "Simulation started!" is printed in the console

Now you can steer by pushing the joystick to the right or to the left, and operate the winch by turning (rotating the stick around it's vertical axis) the joystick (if you use the Extreme 3D joystick).

Apart from the steering, also the depower settings can be influenced with the joystick. Depowering can be used to lower the forces on the kite in order to reel in with high speeds. Low depower settings will increase the forces and the power but might lead to structural failures of the kite. The three possible actions are:

  • Maximum depower setting - Button 1 + Button 5
  • Minimum depower setting - Button 1 + Button 3
  • Normal depower setting - Button 1 + Button 2

The numbering of the buttons might be imprinted on the joystick itself as is the case for the Extreme 3D joystick. Otherwise it can be tested with the joy_pad.py script in the main directory which prints the pressed buttons. For the Extreme 3D joystick numbering see the image below.

https://bitbucket.org/ufechner/freekitesim/raw/master/doc/joystick_button_numbering.png

The simulation can be stopped by selecting the terminal window in which the simulation runs and pressing ^C (Control+c). Then the user will be asked whether the flight data should be saved as a log-file for later reviewing with the log-file player. Typing 'yes' will require you to specify the name of the log-file (a .df is automatically added as the extension so only the actual name is required).

For real-time simulation speed it is suggested to use a quad-core CPU.

Delft University of Technology, section wind energy, The Netherlands.