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R2Home

GPS Guided Parachute Recovery System

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The goal of the project is to design a system with a size of a tube about 40cm long by 7cm in diameter, which can be released in free fall from almost anywhere, and will automatically deploy a parachute canopy and steer it to a precise GPS point.

The last prototype could be seen in action on this 3 videos :

https://youtu.be/qJxrQNkpKjc
https://youtu.be/yJkMXUxymfg
https://youtu.be/eboGHrurAZI

On this video I'm talking in details about how I went from the idea to the system : https://www.youtube.com/watch?v=vNYQW6N5U98

-- UPDATES ABOUT THE PROJECT ARE POSTED IN PROJECT LOGS --

To reach the goal of the project, we have 3 main technical challenges : 

The first technical challenge : Deploy in a safe way a parachute canopy 


In its initial state,  the whole system fit in a tube of an approximative size of 40cm by a diameter of 7cm. 

And what we want, is to, from this tube, deploy, when we want, a steerable, parachute canopy, also known as a ram-air parachute canopy. 

We also want this parachute canopy to be able to fly in a sufficient enough way, which mean with a high enough glide ratio, and flight speed. 

To solve the first challenge, I first started to use a very small paraglider canopy, it flew very well, but I quickly found an important factor for the deployment of the canopy, the aspect ratio, a paraglider or parachute canopy with an aspect ratio > 3 is very difficult to deploy. 

So I decided to start sewing my own parachute canopies to solve this problem. 

After few canopy sewed (you can count a week of work for the fabrication of a parachute canopy) the deployment of the parachute canopy even in bad conditions (bad folding, no forced deployment etc.) started to go perfectly well (see this deployment test video : https://youtu.be/zbJLBY0XdRM?t=25)


Then, once we have a parachute canopy that deploys properly we have the second technical challenge, to be able steer it

For this we have to be able to pull more or less in a coordinated way on the 2 brake lines of the parachute. 

By pulling on the left rear of the parachute and releasing the right rear, we break the left part and accelerate the right part of the parachute, this makes it turn left for example. 

Pulling both lines at the same time will break the parachute, and releasing both lines at the same time will make it fly faster.

It was therefore necessary to find a system allowing to pull more or less 2 ropes/ lines, each one on about twenty centimeters to have enough control over the parachute canopy. 

The solution chosen was to 'hack' servomotors originally designed for rc sailboats, they are sold with a drum spool, and modified inside to be able to still with a closed loop control, make up to 4 turns in each direction. You can see them in action on this video : https://youtu.be/G4p0SzyaSYA?t=29

Few pictures of the last prototype of the system including the mechanical part with the two servomotors 


Finally the last challenge is to automatically steer the parachute canopy, and this challenge is not yet fully fully solved. 

The idea is the following :

By using a GPS device, we can know where we are in real time, and we know in principle where we want to go, so we can know the angle in which we want to move. 

But then to really move in this direction, we need to know in which direction we are actually moving in reality, so that we can then calculate an error, and a correction to get closer to the direction objective. 

And so the main hard point is, from a certain number of sensors, to deduce in the most precise way possible, the direction in which we are really moving. 

For this there are several solutions : 

  • The first one could be to consider that we are moving in the direction in which the front of the parachute is oriented, for this it is enough to use a magnetometer, however this create 2 concerns : 

- The first is that when there is a little wind, the parachute can drift with the wind, and therefore to go in a given direction, it may for example have to point in another direction. 

- The second problem is that the tube in which the magnetometer could be located moves a bit in all directions, and therefore the magnetometer can very quickly become useless. 

  • The second solution would be to also use a GPS device, as a source of orientation data, since we can draw an angle between where we are and where we want to go, we can also draw an angle between where...
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  • R2Home - From the idea to the system

    Yohan Hadji07/19/2021 at 19:12 0 comments

    Hi there! 

    You may have already seen the last video, but last week I had the opportunity to conduct two new test flights with R2home 

    The idea was to test the latest version of the system with an improved way to deploy the wing, as well as the automatic deployment of the wing at the desired altitude. 

    Here is the modification about the new improved way to attach the drogchute and dbag. 

                                                                  Before : 

                                                                  After : 

    And here is the video :

    I also just published another longer video talking (in english!) in details about the project and the system : 

    I spent a fair amount of time on it so I hope you like it :) 

    See you soon (after few weeks of holidays for me!) for the next part of the adventure! 

    - Yohan

    (For more technical details you might want to go check to github :https://github.com/YohanHadji/R2Home/releases/tag/V0.9

  • What's coming soon ?

    Yohan Hadji06/22/2021 at 19:19 0 comments

    Hi there! 

    The purpose of this project LOG is to give you some news about the project, and explain what's next! 


    1. Technical development 

    As stated in the last project LOG, the system is now mechanically functional. It only remains to design, test and validate its automation. In other words, the system need to do the exact same things but alone. 

    A PCB for the on-board computer has been designed, produced, assembled and tested : 

    The brain of the computer is still a Teensy4.1, but the PCB enable the use of very convenient connectors to connect all external components as well as an integrated power supply circuit for the servo motors, and another one for the computer itself. 

    With it, a very new version of the system has also been designed and is now waiting to be built. 

    A prototype of the actual on-board computer has been successfully tested as a secondary payload on a weather balloon flight on May 26th. The objective was to validate the general operation of the computer in real flight conditions as well as the operation of the GPS device on high altitude ( > 30km). 

    More than 17000+ lines of data were recorded and all subsystems were successfully tested and validated. 

    Here is as an example of the data recorded, the 3D trajectory : 



    2. The project and it's supports

    At the beginning of May the project was selected as one of the 3 winners of the earth day challenge organized by hackaday among 70 projects. Thanks once again to hackaday! This helped the project to gain (again) a little more visibility.

    https://hackaday.io/contest/176995-earth-day-challenge

    https://hackaday.com/tag/earth-day-challenge/

    This also helped to trigger some serious discussions with several institutions to support the project. 

    In particular with the CNES (the "French NASA"). However, it is impossible for them to directly support an individual, and I'm also still a minor. So I decided to join an association known as the Open Space Maker Federation, to find a more official framework to the project. 

    https://www.federation-openspacemakers.com

    I am still the initiator of the project, but other people will also be able to work on the project within the federation. The federation also guarantees open source development. 



    3. What's next ? 

    I have about 3 and a half weeks ahead of me and few goals: 

    The first one is to document much more the system, with the complete publication of the current version (3D model, code, technical drawings, assembly instructions, explanatory videos) 

    The second one is to document much more the project. I'm a bit afraid to lose with the time all the reflexions that I had which pushed me to make some choices. I am thinking about a series of videos to explain everything, but I'm very bad at making videos of me talking in english.

    The third one is to proceed to the assembly of the next version of the system and to test it in flight. The next milestone is to be able to open the wing automatically at a given altitude, and then to flight in a straight line at a given heading automatically too. 

    The last objective is to start working on the flight strategy, that is to say, concretely which trajectory is the smartest to reach the landing point.

    • Are there some altitudes where the flight is more interesting than others?
    • Is it necessary to take into account the weather forecast of the day? 
    • Is it better to try to fight the wind or is it better to fly into the wind?

    These are all questions for which we will have to perform many tests before being able to find an answer. 

    Here are also the "bigger test" opportunities that will be available then : 

    • Test of the complete system dropped from a drone at 300-500m of altitude (with the competent authorities) 
    • Test of the flight computer only again on a weather balloon as secondary payload 
    • Test of the complete system as main payload on a weather balloon flight up to 30km of altitude,...
    Read more »

  • Milestone

    Yohan Hadji04/20/2021 at 17:29 0 comments

    Hi All! 

    In the last project log it was about failures and problems to solve, in this one I'm happy to tell you that it is about success and a big milestone reached! 

    R2Home is now perfectly functional on the mechanical part, that is to say that now all that remains to be done concerns only wiring, programming, things a little easier to test! And less risky!

    Here is a small picture of the latest version of the system, including a camera, data-logging, telemetry, manual RC control. 

    On the background the new "drop drone" (DJI S800 Evo). This drone is now only used to lift the system and not anymore as a static line deployer for the system. 

    Now the system is fully autonomous in terms of deployment forces. 

     - So you'r talking a lot about the deployment but can we see how is it working now ? 

    Sure sure! Here it is : 

    Step 1 : be in free-fall 

    Step 2 : release deployment bag 

    Step 3 : the wing is pulled out of the dbag, the drogchute is "disabled" (see last log for more informations about the magic drogchute) 

    Step 4 : the wing inflate, and fly ! 

    (for a slightly higher quality video of this same deployment, follow this link : https://youtu.be/pFeydoTiUqQ

    Here is now the complete video of the latest test : 

    And here is a special video to celebrate this milestone : 

    Thank you to all those who have supported the project since the beginning, nothing would have been possible without them! 

    If you want to take part in the adventure too, follow this link : https://gofund.me/060d2215

    Can't wait to work on the next part of this project! 

    - Yohan 

  • Test, fail, learn, RETRY!

    Yohan Hadji02/19/2021 at 09:16 0 comments

    Hi there! 

    In France, every 2 months or so there are school holidays, 

    And for me holidays = parachute test. 

    But when you do a test, it's because you have something to test, so this time what did we test ? 

    The weather balloon that we want to recover usually explode at an altitude of 30km, at this altitude there is almost no air. And what we want is to open a parachute that is kind of hard to open, so we are not really in the best conditions to open a parachute at 30km of altitude directly when the balloon explode. 

    Also, to open the ram-air canopy parachute, we need what we will call an extractor parachute, which is a small round parachute already deployed in the air during the ascent, that will give us during descent, at the chosen moment, the force needed to extract the ram-air canopy from it's deployment bag in which it is folded during ascent. 

    The last point you need to get, is that it is dangerous and therefore illegal to drop an object in absolute free-fall from any altitude (at least where I am) this is why at any moment of the flight we don't want fall with a velocity >5 m/s 

    To sum up, we need to open the raim-air parachute canopy at a lower altitude than the ballon burst altitude (30km), we need a small round parachute to open the ram-air canopy, and we don't want at any moment of the flight to fall at a velocity > 5 m/s 

    And this, is the solution :  

    I call it the collapsable-dragchute  

    The idea is that, we need a big enough dragchute to fall with a velocity < 5 m/s before the opening of the ram-air canopy, but we also need it to be as small as possible once the ram-air canopy is opened, because otherwise it will make impossible the flight of the wing. 

    So to sum up : 

    After the burst of the balloon, everything come down under this drag-chute, at a velocity < 5 m/s, at the desired altitude (where there is enough air of canopy inflation) the dragchute is used to get the canopy out of it's deployment bag, at the same time, the "collapsing line" of the dragchute il released by a small mechanism, the wing is opened, and the dragchute is collapsed. And everything is perfect ! 

    Well at least in theory, because reality is really hard with concepts that seems so easy :) 

    So this objectif of this test was : 

    1. Like each time, get more data on the performance and the flight of the raim-air parachute canopy, see how it react to commands, how it fly with a bit of wind etc etc

    2. To test this new concept of collapsable-drogchute 

    (3. And also last point, get better at organisation of the test flight, with a more "streamlined process", for example with automatic flight mission for the drop drone etc etc..) 

    And if the first and the third mission have been perfectly accomplished

    An example of the data we got from one of the flights : 

    An example of automatic mission with INAV running on the drop drone  

    On the second mission, it is unfortunately not a total success, and at this point, the story continue with this video : 

    As explained in the video, what happened is that we got a tangled dragchute, but what is exactly a tangled dragchute ? 

    If you take a look closely at the "The solution" video, you will see that to get this collapsable dragchute we need to use two different line, so the dragchute before collapse is connected with two line to the system, and what happened there is that during preparation or during ascent, a part of the parachute got stuck between these 2 different lines, which once the system was released got even more stuck between the lines, because they were under tension due to the low but high enough drag of the tangled dragchute.  

    So I've tested, I've failed, but now I've learned, we need to find a way to have one and only one line on this collapsable parachute. But we need two of them to make it collapsable, so how is that possible ? 

    One idea is to get one line into another, like a wire in a tube, but this...

    Read more »

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jhdewitt wrote 04/29/2021 at 11:44 point

cool idea good luck

  Are you sure? yes | no

freeflightlab wrote 02/18/2021 at 23:48 point

Can't wait for your update!!! Really great work Yohan!!!!

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