Pete Hollands's Posts (12)

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Flight Demo of Matrix Pilot 5.0

This is a flight demo of the recently released MatrixPilot 5.0flying the helical Turn algorithms by William Premerlani.

MatrixPilot is a relatively small open source GPL v3 licensed Autopilot, which provides a platform for DIY enthusiasts to experiment with new algorithms and ideas. It does not have a large user base, partly because any change in it's configuration requires a recompilation of the code.  The official announcements for this 5.0 release is on the uavdevboard discussion list.

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A Demo of MatrixPilot Helical Turns

A Demo of Helical Turns with an EasyStar in HILSIM / X-Plane 10 from Pete Hollands

A few days ago William Premerlani posted the theoretical maths behind a new control algorithm for MatrixPilot called Helical Turns.

This post shows a practical demonstration of flying MatrixPilot Helical Turns using an Easy Star in Hardware In The Loop Simulation (HILSIM).

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DIY Drones T3 racing in Venice

What's going on here? This is a "Virtual Venice UAV race". It's based on the DIYDrones T3 figure of 8 competition.

The screncast's purpose is to show how pilots can potentially fly their planes in different parts of the world, and then have their geo position and time base altered so that they end up racing side by side in Google Earth.

My spoken commentary is complete fiction. I just wanted to create the human emotions that a race meet, can engender. (I actually flew the same planes somewhere near Reading in the UK on two different days).

Now, using the latest flight analyzer, any group of MatrixPilot's can have a race together, although they may actually be on opposite sides of the world. In the future, all MAVLink compatible UAVs shoud be able to do this as well. (Someone still has to develop the software).​profiles/​blogs/​restarting-the-t3-contest-now-with-copters​p/​gentlenav/​

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MatrixPilot 3.1 Released



MatrixPilot 3.1 is released. The project continues to mature, with a fantastic IMU that is still moving ahead with deep research from William Premerlani. Ben Levitt continues to add amazing features such as the built-in firmware for the OSD hardware that can be attached to the UDB3. This means the UDB3 can display it's internal thinking (such as next target waypoint, direction of next target, and maximim G-force being pulled) onto the video screen of the pilot.


Anyway here is a quick summary of the latest changes ...

What's New in MatrixPilot 3.1

  • Major IMU improvements, including "dizzy-proofing", automatic inflight gyro calibration, and compensation for magnetometer latency.
  • Live camera tracking of one UDB from another.
  • User-configurable OSD layouts.
  • Full support for the DIYDrones MediaTek GPS.
  • Maintain minimum ground speed. The speed control loop is now based on the smaller of ground speed and air speed.
  • Improvements to inverted stabilization.
  • Improvements to the Flight Analyzer tool.
  • More bug fixes.

There is a lot of talent and development occuring around MatrixPilot at the moment, and I look forward to working with all the newer developers to integrate their new features into MP over the next few months. Thanks everyone.


Best wishes, Pete



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Reduced Yaw Drift / Fast Gyro Sampling with the UDB / MatrixPilot from Pete Hollands .

[Note: Apologies for the low sound volume in this video. Please turn your volume up.]

This is a demonstration of the reduced Yaw Drift which is possible when sampling the gyros at 30,000 times / second (Thanks to William Premerlani for this R&D and code).  Using QGroundControl and the MatrixPilot MAvlink implementation, I show a real time graph of the resulting negligble yaw drift in the UDB IMU.

In the demo I do refer to the accelerometers quite a bit. I should really have been focussing on the gyros. It is the high sampling of the gyros, and the integration of the resulting data which leads to the low yaw drift. So please ignore my comments about the accelerometers.

Demonstration uses Revision 790 of MatrixPilot_mavlink branch at this address​p/​gentlenav/​

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Testing a DIYDrones magnetometer in HK's GCS

Testing a DIYDrones magnetometer in HK's GCS from Pete Hollands on Vimeo.

I test the DIY Drones magnetometer ( HMC5843 magnetometer breakout board ) using Happy Killmore's Ground Control Station connected using SERIAL_UDB_EXTRA telemetry format, to a UAV DevBoard V3 running
MatrixPilot (revision 729 of trunk).


UAVDevBoard / MatrixPilot:​p/​gentlenav/​wiki/​Home?tm=6

HK GCS:​p/​happykillmore-gcs/​

DIY Drones Store:​HMC5843_Triple_Axis_Magnetometer_p/​br-hmc5843-01.htm

Self Calibrating Mathematics, and software to integrate via I2c written by William Premerlani:-​profile/​WilliamPremerlani

Source Code:​p/​gentlenav/​source/​browse/​trunk/​libUDB/​magneto_udb.c

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Matrix Pilot Camera Targeting: Tree Test - Software Stabilized

Strategy: Have MatrixPilot / UAV DevBoard (UDB) point camera roughly in the right direction.

Take out the jitter movement using software stabilization.

The above flight was flown on a day with 10mph of wind, with a lot of turbulence (I included the landing in the video to show the turbulence).

1. The UDB is calculating its orientation 40 times / second using a 16 bit Direction Cosine Matrix

2. I use se Bill Premerlani's "High Bandwidth Dead Reckoning", which means MatrixPilot knows it's

absolute position 40 times / second, by integrating the accelerometers. The accelerometer positions are

corrected by allowing for the GPS delay and some of the GPS dynamics (GPS info arrives at least 1

seconds after the real event).

3. The camera code computes the target location from the above 40 times / second.

The main issue at the moment is that I'm using a camera with progressive scan. This causes each frame of the image to be distorted when the camera rotates (accelerates) in a new direction.

Pitch Servo resolution is 0.2 degrees which translates into moving the picture 7 pixels. Ideally it would be at least 1/10th of that, e.g. 0.02 degrees.

Photos of the build of this project are here.
Main Wiki for MatrixPilot is here.

For reference the flight path, in autonomous mode, is shown below.

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Two short videos showing how to analyse telemetry in Google Earth.
I use a python script called, which is still fairly rough around the
edges (alpha quality), but is useful. In part 1 I show how to use the script to create a
spreadsheet and Google Earth KMZ File. In part 2, we explore the telemetry in Google Earth.

Converting Telmetry for Google Earth Analysis - Part 1

from Pete Hollands on Vimeo.

Converting Telmetry for Google Earth Analysis - Part 2

from Pete Hollands on Vimeo.

If you are a budding Python programmer, and you also know (or want to know) about KML,
then please feel free to modify the program. Stay in touch.

Further information about this project ....
Photos relating to the UAV Devboard are here.
Photos of the re-build of my Twinstar 2 and incorporation of the UAV Devboard are here.

Happy flying, Pete
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