I´m in involveld in several airship and DIY related projects. For example we´re at the moment trying to fit an Ardupilot in this science vessel: https://www.youtube.com/watch?v=cNne5dP-eeM
Anyway, I wondered a long time why there are not much airship UAV´s out there and figured out that the most likely reason is the lack of easy accessible platforms. This is why we recently published the DIY high performance airship silent_runner http://www.silent-runner.net/index.php/Main_Page
Now we´ve built quite a few of these ships and gathered some experience to work on the next generation. This might lead to a kit that contains some of the essential components like the envelope, structure parts and basic electronics.
So I believe it´s a good time to see if there are some key features a ship should have, to be useful for the UAV community. At the moment design criterias are:
- small (has to fit in a car)
- efficiency (run half an hour on a 500mAh/7.4V Lipo)
- 30g of payload (arduino micro, Xbee + some sensors)
Is there interest in such a system and would you add some more critical abilities?
Some outdoor footages here:
I´m pretty sure that control surfaces are the better way to go, and low speed is by the way a huge problem when you go outside.
Anyway, there are two ways to hook up the motors in your specific configuration.
You could patch a second small arduino to the Yaw line of the ardupilot that takes care of providing the PWM signal for your two engines. That way you can make the arduino control all that stuff.
The other way would go deep into the APM code and track the line of the YAW control. I´ve not yet looked that deep into the code but it seems well written and documented.
Very, very interesting...
If it can fly by APM, adapting code of arduino micro, would be great!
I'm really interested about, more precisely, how APM could control vectorized system of engine axis.
I hav tried with control surfaces but its not giving enough force to turn 8m long airship thats y we have choosen 3 motor configuration for throttle , lift and yaw respectively and also speed is approximately 2m per second.
We have used plus configuration fo fin I.e 2 vartical and 2 horizontal fin. I will paste the link of picture once I reach to my place as am travelling .
And I went through code throughly. .track yaw controller line.
Since the problem is that APM gives the output to yaw servos which changes the direction immediately but in yaw motor, motor has to stop first in order to rotate in other direction or give force in other direction so mismatching of output to yaw...
I tried to put intial output of yaw servo to zero bfr it gets the output from yaw controller (as motor has to be stoped so output zero will complete this task )
Result of this modification is that yaw servoes is not even responding to yaw controller output...
Can u plz suggest something which can be implemented to slove this problem...
Bimpduino is suitable for indoor airship. It wont work with outdoor airship I think.
This is what i was talking about
Sorry, have been on aerial survey yesterday and no time to reply.
But that´s an awesome one, congratulation to that nice airship platform. Actually it seems like your fins are big enough, I´ve flown airships with smaller fins and pretty good control. Remember that for using the fins you always need enough speed.
I think I understand your problem better now, you´re trying to use the motor in the backtail to be controlled by the Yaw channel? This might works at no/low speed but will stop working once you fly faster as drag effects on the hull start to be stronger than the motor force. You should rely on both, fin and motor, to maintain control.
Anyway, we had the same issue in a cuple of airships and solved it in different ways, here are the ideas:
1. Replace the brushless ESC and motor by a brushed bidirectional motor (RC car or ship). They are cheap but a bit weak and heavy. But these motors don´t have the problem with stopping as the thrust is reversed. We have used that as a yaw motor just wired to the normal servo line. It works great.
2. Put the Yaw motor to the moving part of the fin. That way the servo of the fin rotates fin and motor and creates a vectoriced thrust system. That is pretty elegant and will work on low and high speeds. But you need a reinforced fin.
3. Try to solve it from the programming side. Most good Brushless ESC have several brake options, try to activate them, this often leads to better results, but as the control movements of the APM are rather quick and fast, it will probably not work reliable. The other option is to smooth the yaw output in the APM, but don´t ask me how to exactly do it.
However good luck with your project, would be awesome to see some videos of the test flights. By the way who manufactured the envelope of the ship? Is it tight and reliable?
I was waiting for your reply but no problem at all.
Yes you understood well.We had field trial with this envelope and fins(yaw motor at tail) and yes it was not working good at high speed. So for new airship we are going to use both yaw motor and control surfaces(servos).
But problem is that how I implement this with autonomous . I need to control yaw motor because main objective of project is blimp for surveillance so it may has to hover, moving with low speed or high speed(less chances).
Anyway,I thought about break option available for reversible ESCs but am not sure how to implement it with programming. And what you mean by smoothing the yaw output in APM. I mean am asking about smoothing the output. Is it related to filtering the output of yaw control in APM?Am sorry you said "dont ask" but am still asking.
You can see videos of field trial with this envelope on the following links, but it is not autonomous.
This envelope is manufactured year ago, that time i was not working on this project. So exactly I don't remember but yes it is designed by some researchers and fabricated by mechanic.
Thankyou so much for giving your time.
These are beautiful footages, great work, I love how the birds are flying around your airship.
It looks like your airship is rather slow. May I ask how much power your forward thrust motors have? For a vehicle of this huge size I would propose at least 2x 60A Brushless motors for suffcient speed and thus control while facing wind. Superior speed, a slender body and control surcafes This is in my opinion the key for stable and secure airship flight.
As seen here: https://www.youtube.com/watch?v=cNne5dP-eeM
At the moment I don´t have an APM here available for test programming. But you can first try the ESC modes. Have a look in the manual of your ESC, normally you can programm them quite easy using a couple of controler positions while listening to "beep"-feedback from the wired motors. This way you can set different brake modes and so on, this might solve your problem.
Another idea that once lead to better results was to use the roll channel of the APM which is also coupled to the Yaw in airplane mode.
At a later point you´ll anway have to go into the hcode of the APM, as it is designed for airplanes and thus do not allow hovering over a position. It will do weird things when trying to set airspeed to zero. We are currently trying to solve these problems as well and can share code maybe at a later point of that work.
Specification of motors are here https://drive.google.com/?authuser=0#my-drive
Well, one thing i want to say that there is no rolling motion in airship and i have pretty good idea about programming if logic is clear. So I developed new firmware for airship in which no rolling motion was induced and also no failsafe mode, as in fixed wing aircraft if speed is less than 5m/s than autopilot goes in failsafe mode so I have to remove all these things. But problem in that is when i dump that code in APM and try to connect to MissionPlanner ,than APM and Mission Planner uses MAVlink protocol for communication, This protocol verifies the parameter both the side(Mission palnner and APM) and since no rolling ,stickmixing and failsafe is include in apm firmware so It wont established communication between them.
And I will defiantly go through ESC breaking option once (as it seems pretty good idea at this point),after finishing my academics examinations. Maybe I will work on it in May.
Once again thankyou so much for your suggestions.