Vassilis’ Projects

I was able to do a quick test with both sensors connected. The barometric altitude together with the GPS altitude is shown in the plot below.

There are some discrepancies at the lower altitudes that I will need to work on a bit more. The coefficients for converting raw values from the sensors to the actual altitude and airspeed are calculated experimentally so some tuning may be required.

The source code was also released. This is code I am using to test the sensors and does nothing more than sending the altitude and airspeed data to the GCS. The next step will be to modify the airborne code to make use of the airspeed (for example maintain constant airspeed by adjusting the throttle).

I had a successful flight with the EagleTree airspeed module connected to my TWOG. I did not have to do any hardware modifications, the sensor has an I2C interface that I connected directly to the TWOG I2C port. I was able to figure out the slave address and decode the raw output of the sensor. The results are quite good, the module is low cost and comes with a very good pitot tube (Prandtl style, pitot-static tube) that includes static and dynamic ports. For now I am simply sending the airspeed through the telemetry, the next step would be to modify the autopilot code to regulate the throttle in order to keep the airspeed constant (and a minimum ground speed). I am also working on interfacing with the EagleTree altimeter sensor.

Following is the data from my last flight, there was no wind and I tried to keep the pitch close to zero for most of the flight in order to be able to compare ground and air speed.

I will release the source code as soon as I have both airspeed and altimeter tested.

My Paparazzi / EasyStar entry won first place in the first round of the DIY drones T3 competition. Very fun competition and the timing was great, right after I finished tuning my EasyStar with Paparazzi. I did damage two LiPo packs running at full throttle but the airframe and autopilot performed great! The best part for me was getting to learn the Paparazzi flight plan editor, extremely powerful and flexible. Total time to complete the course was 49.5 seconds, a lot of very good entries with most autopilots represented. This was a great initiative of Chris Anderson and Gary Mortimer from DIY drones, the plan is to have a contest once a month. In fact the September competition is already ongoing. A video and a few screenshots follow.