Running Piccolo Log on Flightgear

Young Mo KangECE @ UIUC

Piccolo?

• A family of autopilot systems from Cloud Cap Technology

• Loaded on UAVs (Unmanned Aerial Vehicles)

http://www.cloudcaptech.com/piccolo.htm

What?

• Sensors (accelerometer, gyroscope, …)

• GPS• Communications link for data

transfer

UAV

Ground station

And…

• Piccolo sends real-time telemetry data to the ground station computer

• The ground station computer logs the data on a text file

Sample log file

What about Flightgear?

• An open source flight simulations program

• Simulates a flight

http://www.flightgear.org

How?

• It has to read in data via1. File

2. Socket (TCP or UDP)3. Namedpipe4. Serial

Setup

• A server broadcasting data• A client running Flightgear

server clientNetwork connection

Tasks

• Convert the Piccolo log file into a replay file

• Broadcast the replay file to client

Conversion

• From Piccolo log file• To FGNetFDM data structure defined in net_fdm.hxx of Flightgear source file

• Simple task if all correlations between Piccolo log file and FGNetFDM data structure are figured out

Correlations

• Many can be directly retrieved from the log

• Some need to be calculated from other values

• And others to be figured out

Once figured out

• Data values are assembled into the structure

• Little endian to Big endian byte-order swapping

• Saved as a replay file

Broadcast

• Reads in the replay file just created• Whenever Flightgear receives the

packet, it will display on the screen immediately

• Data need to be transmitted at the same rate as they were logged

• Decide whether to broadcast a packet of data or wait

Time stamps

• cur_time stores the UNIX time value• Broadcasting program needs to refer to the

value for each time frame data• However, UNIX time is accurate up to 1 se

c• MAX 1 frame per sec• Causes abrupt changes in scenery on Fligh

tgear

Solution

• Instead of UNIX time, Piccolo’s system clock time is stored in cur_time during conversion process

• clock time is accurate up to 1 ms• x1000 more frames per sec possible• Smooth scenery transition (of course, only

if data were logged at high enough frequency)

Testing

server

client

Thoughts

• Can replay test flights with/without manipulations of the log file

• Can be implemented to any type of log formats NOT RESTRICTED TO Piccolo with slight modifications

• Can be used to test and simulate optic flow algorithms by changing to cockpit’s view