Crazyflie Position Control and Guidance

Python library for controlling the position of the crazyflie 2.0.

Requirements

• Python 3.6
• Python vicon built for python 3.x
• Crazyflie Client with ZMQ input enabled

Program Structure

• main.py is intended to be a high level command script for controlling the crazyflie

  • uav.takeoff(altitude)
  • uav.goto(x,y,z)
  • uav.land()

• cfControlClass.py creates a queue list for communication and starts up threads

  • self.startVicon() spawns vicon thread that captures self.name position data
  • self.startControl() spawns control thread that outputs (R,P,Y,T) commands to cfClient based on current position and set-points
  • self.startLog() spawns log thread that writes data from the PID thread to a .txt file
  • Other threads can be easily added to the class and passed the QueueList dict for passing vicon data, set-points, etc

• viconStream.py collects position data from vicon system

  • fake data can be used by setting fakeVicon arg to True
  • Position data is .put into two queues
    • ["vicon"] intended ONLY for PID. Do NOT .get() data from ["vicon"] queue for other threads, use ["vicon_utility"]

• PID_CLASS.py sends ZMQ messages to cfclient for controlling position

  • Accepts set-point messages from ["sp"] queue
  • Pulls position data from ["vicon"] queue
  • Outputs a dict to ["dataLogger"] queue for logging

Instructions:

• cd inside cfControl folder
• For new scripts, import cfControlClass
• See demo.py for example

Known problems and future improvements

• Quad stability depends on high update rate vicon and PID threads. Accessing ["vicon"] data slows down control thread and causes instability
• Implementing a pub-sub message system to prevent thread communication bottle-neck is needed. ZMQ has pub-sub
• Geofence
• Rollover protection
• Landing velocity control
• Takeoff veloocity control
• Guidance selector
• Sub to crazyflie and log