I know that people have discussed this before, but I have yet to see anyone declare that they built a worthwhile system or create any documentation. I did see some youtube videos using pyro charges, but that makes me nervous. I want to use CO2. If anyone has any information or observations I would love to hear it as I start this project. I am throwing all my ideas out there to see what people would do differently, or to find out if it is a pipe dream (pun intended). So here we go!
Goal:
Develop a lightweight and independent failsafe system for multicopters.
Idea Summary:
Use an Arduino micro with an accelerometer to trigger the ejection of a parachute. The system will have to be independent of all other power and mechanical systems on board so it will have it's own power source.
Detail:
This would be primarily designed for multicopters carrying a large and expensive payload like a DSLR. The goal is to slow the copter down enough so that the payload is less likely to be damaged if an emergency occurs. The independent power source must be small and light weight.
I researched different methods to see if anyone had tried to worked with Arduino and pressurized CO2. Unfortunately, there were only unanswered questions or some hypothesis with no follow up. While brainstorming I thought about paintball and thought that a solution might exist there since they use electric triggers in many of the markers.
I picked the CO2 system from the Tippman Tipx pistol because it was built around CO2 cartridges, instead of a refillable bottle system. I think I can use the puncture valve assembly from this marker to interface with the CO2 cartridge. I need to figure out if the puncture valve assembly will actually act as a valve, or if it only provides the breach. I also need to find out if the an e-trigger solenoid provides enough force to puncture the cartridge, or if it has to be manually punctured.
The Solenoid will be triggered by an e-trigger assembly, this assembly will be hooked up to an arduino micro with an accelerometer. The accelerometer will trigger the solenoid when either the multicopter tips past a certain point or the rate of descent reaches a specified velocity.
The gas from the CO2 cartridge will travel through a pipe into the adjacent tube that is packed with wadding and a parachute. I will need to run some tests to see how big the chute needs to be, but I am sure it will be significant.
Reference:
Tipx Exploded Diagram: http://www.tippmann.com/pdfs/manuals/TiPX%20Schematic%208-11.pdf
Valve Puncture Assembly: https://www.pbsports.com/Tippmann-TiPX-Puncture-Valve-Complete.html
Solenoid & e-trigger: https://www.pbsports.com/Virtue-Redefined-Tippmann-A5-Upgrade-Board...
Arduino Micro: https://www.adafruit.com/products/1086
Accelerometer: https://www.adafruit.com/products/1018
Here is a really rough draft of what I am thinking:
So lets hear what you think!
Comments
Hi Patrick, Great! What is the expected weight of your UAV, and what descent speed are you targeting? I can tell you what size chute would be recommended.
Gene Engelgau
KI6IBL, NAR 86770 / TRA 12243 - L3
http://fruitychutes.com - Consumer and Aerospace Recovery Solutions
408-499-9050
Thanks so much, this is exactly what I was looking for!
I can attest to the qulity of the Fruity Chutes stuff. Hi Gene.
Hi Guys, I came across this and felt this might be of interest. We are working on a turn-key solution for UAV use called the Peregrine IDS (Integrated Deployment System). It is a completely integrated CO2 deployment system with the chute pressure packed into a twist-lock carbon fiber canister making changing in the field easy. It will feature our ultra compact and efficient Iris Ultra chute. Here is more information:
http://fruitychutes.com/uav_and_rpv_recovery_parachutes.htm.
Contact us if you want more information about this or our other UAV recovery products.
Thanks for your time!
Gene Engelgau
KI6IBL, NAR 86770 / TRA 12243 - L3
http://fruitychutes.com - Consumer and Aerospace Recovery Solutions
408-499-9050
@Stephen Gloor Thanks! This looks really promising. I will definitely have to check this out.
The best parachutes I could find are the High Power Rocketry ones from here:
http://www.the-rocketman.com/chutes.html
They also have a spring loaded pack for UAVs that you might consider instead of the CO2 system:
http://www.the-rocketman.com/model-recovery.html
And what is also interesting is descent rates to size the parachute:
http://www.the-rocketman.com/decent-rate.html
Have been doing a bit of research and have found the model warships that fire BBs - they have interesting fittings available. This article explains a bit and goes into the fittings in some detail:
https://rcwarships.org/rcwarships/nwc_new/?category_id=29&menua...
On this site is a regulator that you could use to pierce the tank:
http://palmer-pursuit.com/cart/rock-the-boat-regulator-p-618.html
If you lead the output of this regulator to one of these valves:
http://www.clippard.com/part/MAVO-2
This is a normally open valve. Make it so you close it with plastic or metal fitting that is connected to servo or solenoid. Removing the fitting would allow the cartridge to discharge the CO2 all in one go. This way you do not have a heavy electric air actuator. Nor do you have a heavy servo with enough torque to close the valve to let the CO2 out if you had a NC or normally closed valve. Your system does not have to fire again so the NO valve would work best. Also it is easy to have a positive disarming system. Just lock the fitting in place with a pin and red flag that has to be removed for flight. If the pin is in the system is safe.
I think you're going to make this project much harder if you try to deploy the chute automatically. That's easy to do in a rocket, it's trivially easy to decide when to deploy if under computer control (and even if not, the physics are easily handled by "kids" for a good-guess time delay), plus no props. PS: black powder doesn't explode, and you don't need much either, cheap and easy to ignite electronically.
For first steps, I assume you'd be doing all possible to save as much of your copter as possible, and I think that would probably include shutting off the motors once you're in a situation when you know your motors can't save you and are only "hurting". IOW the chute deployment is fully under user control, and is merely one step in your trying to save your copter.
Don't even consider trying to deploy at 25' or some other baby-fall lol altitude at first. The requirements of a chute that will make any difference (i.e. slow the copter down enough) from such low altitudes will probably be a continuous burden on your flying. It would have to be quite large and have some fiendishly clever packaging to deploy and have worthwhile effect (in the second before it would otherwise hit the ground) without some very strong ejection method.
All you have to do is get that chute out into the airflow and it will open quite quickly. What I'm saying is to simplify with your system, then elaborate once you see any real issues. Besides, it will be fun to play with, and you will have more confidence that your "chicken switch" actually works when you need it.
Oh yeah, don't forget a shock cord of some type, the effect of a chute opening on a free-falling craft can be damaging itself. Perhaps attach the chute package to the copter with a few feet of 1/16" SS aircraft cable, this stuff isn't that heavy. I'm thinking it would be wrapped around the outside of the folded chute and will quickly "spring" open in free air. I'm thinking it'll take just long enough for the cable to uncoil that the actual chute package (the delicate part) would then be a couple feet away from the copter body before it starts to open, such that copter orientation and possible entanglement become less of an issue.
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