TU Delft - Search and Rescue with AR Drone 2

Introduction

The highly maneuverability and stability of a quadrotor inspired us to make an autonomous search and rescue vehicle. For this the AR Drone 2 was used. The goal of this project is thus to further develop the AR Drone2 in a robot capable of performing an autonomous search mission. All the steps taken are described on this page.

In order to achieve this goal we decided to work with raw data. The data was obtained by creating drivers capable of extracting and interpreting sensor data from the AR Drone2. In order to get the quadrotor flying paparazzi was used. For simulation JSBSim was used, which was then visualized using Flight Gear. The final section of the page will concern with the subject of making the quadrotor autonomous.

How all the data was obtained is presented in chapter 2. In chapter 3 it is described how to get paparazzi working on the drone. Next in chapter 4 we present how simulation was done and finally the proces of making the drone autonomous is described in chapter 5.

Data acquisition

GPS

The GPS we use with the AR.Drone2 is the BU-353 GPS. To make good use of this GPS we had to create our own driver for it. That way we could extract the received data from the GPS and output it in our preferred format. To create our own driver, we first needed to know how to retrieve the data from the GPS. We downloaded the Linux USB Driver and learned from the readme that you could use the GPS with the following commando:

su root

stty -F /dev/ttyUSB0 ispeed 4800 && cat < /dev/ttyUSB0

With this we found out that we needed to create a program that opens the /dev/ttyUSB0 device and reads it at a baud rate of 4800. We had to pick a datatype since working with several datatypes at the same time would be confusing. Therefore we had to extract the right datatype string from the data strings output by the GPS and format that string into useful information.

Paparazzi on Drone

Integrating drone in Paparazzi

""Paparazzi Autopilot System"" Throughout this project, on several different occasions, it will be apparent that the AR.Drone was never meant to be used in this fashion. In addition to this, Parrot SA has a vested interest in maintaining the exclusivity of its product, rightfully so. With what little information is publicly available it is the team's objective to load the open-source autopilot system, Paparazzi onto an otherwise copyright protected piece of hardware. In order to do so a few steps had to be taken to get Paparazzi onto the AR.Drone 2.

• Reverse engineering the AR.Drone2

Simulation

JSBSim

Creating A Flight Dynamics Model

In order to control the otherwise highly active dynamic nature of the quadrotor, an autopilot system will be necessary because the reaction time of the pilot will, otherwise, not be sufficient to maintain stable flight. The autopilot system will be created in Paparazzi for which a prerequisite is a proper flight dynamics model (FDM). To create the FDM the team will use JSBSIM, an open-source, platform-independent, flight-dynamics and control software library. Installing JSBSIM is covered for several different operating systems on the Paparazzi Wiki, Installing JSBSIM.

Once JSBSim had been installed, the actual work could begin. Flight Dynamics and the creation of an individual model for an aircraft is essentially a case study regarding its control, stability, and performance. To model those three dynamics aspects is essentially what JSBSIM was used for but before work could begin, JSBSIM would first need to be fed a configuration file. The configuration file is written in a .xml format and, naturally, is unique to each aircraft. Although not applicable to this project, it is worth mentioning in the event that the reader of this page is not following the instruction exactly and is using it more for reference, there is a tool on the JSBSIM page called Aeromatic, which is a capable .xml configuration file generator. For those following this project closely, a link will follow for creating a suitable JSBSIM .xml configuration file for the AR.Drone2.

• Creating a JSBSIM .xml Configuration File for AR.Drone2

Flightgear

Without actually using the drone itself, and only the previously developed JSBSIM configuration file, a simulated drone can be flown in Flightgear. To do so, a CAD model of the drone is implemented to give a visualization to the simulated model. Flightgear is the preeminent open-source flight simulator backed by a large community of active users. More on the software can be found on the Flightgear website.

Creating an airframe

From the Paparazzi GCS we need to add an aircraft and attach an airframe, flightplan, settings, radio and telemetry files.