Qualisys motion capture systems can provide high-speed, reliable, precision position tracking for the closed-loop control of Bitcraze Crazyflie quadcopter systems. This repository contains a collection of resources for developing Crazyflie projects and related applications that interact with QTM.

• In QTM, the rigid body that corresponds to the Crazyflie quadcopter should have custom Euler angle definitions:
  • First Rotation Axis: Z, Positive Rotation: Clockwise, Name: Yaw, Angle Range: -180 to 180 deg.
  • Second Rotation Axis: Y, Positive Rotation: Counterclockwise, Name: Pitch
  • Third Rotation Axis: X, Positive Rotation: Clockwise, Name: Roll, Angle Range: -180 to 180 deg.
• The capture rate should be 100 Hz.
• The Crazyflie USB radio dongle must be set up correctly.
• The Crazyflie drone should be placed on the floor, visible to the cameras, with the front of the Crazyflie pointing in the positive x-direction of the QTM coordinate system. (Important: If the front of the drone is not aligned with the x-direction it may lose control and crash. The stability of the closed-loop position control algorithm is predicated on correct initial alignment.)

NOTE: The scripts are currently deprecated as they use an older version of the Qualisys Python SDK.

The example Python scripts in this repository are intended to serve as a starting point for implementing custom Crazyflie applications.

All scripts have been tested with Python 3.6.4 running on Windows 10 in a conda environment.

• cflib
• qtm
• xmltodict

Albeit small and lightweight, the Crazyflie drone may damage itself, along with objects and people in its vicinity upon contact. Please be mindful of the surroundings and remember that a motion capture / position tracking system does not necessarily provide facilities for collision avoidance.

Additionally, while controlling Crazyflie drones programmatically using a Qualisys motion capture system, please be aware of the following issues:

• Running the control loop that issues send_setpoint() commands to the Crazyflie while no position information is relayed (via send_extpos()) may cause the drone to fly uncontrollably and crash. The control loop that issues commands to the Crazyflie must be stopped before stopping streaming from QTM.