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Australia, NSW, Springwood
Joined Dec 2012
130 Posts
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Arkbird OSD mini review & comparison with Cyclops Storm
Hi all, I've had five FPV flights with the Arkbird OSD now and am pretty happy. It's not perfect, however, for the $$ it's pretty good value. It comes with a pretty decent set of cables though I wish the GPS cable had been 15cm longer and extended this myself.
First, my setup: Bixler1.1, 808 #16 V2-D cam both recording 720p and streaming video for FPV (powered through OSD), Akrbird with V3-1010 firmware. I've compared video quality from the 808 against a friend's basic fatshark pred1 cam and the 808 is clearer and sharper (once you refocus the lens to infinity). The OSD screen data is very clear and well laid out. The menu system is a breeze to use with the Tx AIL/ELEV channels. They've thrown in plenty of things you can configure like channel end points, max roll/pitch/yaw degrees, etc and this all works well in flight. There are a couple of new menu options in fw1010 I don't know the function of and are not in the original manual: ACC Coupling (default 100%), Cenforce Para (50%), and a Quad Mode Test menu. The GPS locks on really quick on power up once you've done the setup (about 30s first time). It locks on to 7-10 satellites during my flights so far, no issues with accuracy. Voltage and current readings on screen have calibrations you can do in the menu system so you can adjust if required - my OSD was reading 0.2v lower than my battery checker. Easily adjusted. Once the neutral point is set right, the plane can hold straight and level flight reasonably well hands off. Turbulence and gusts will unsettle the balance mode a bit but it does drift back to the original heading eventually. Okay if you're high enough not to get into trouble if the plane spends a few seconds banking, but you have to be ready to react if flying lower. The gyro mode is so-so; I didn't notice a lot of additional stability over turning it off but I need to experiment with increasing control horn movements as per the manual. RTH mode works as advertised and I'm really pleased it has throttle management to maintain a minimum ground speed you set in the menu. Once overhead it does circle in around a 80m circle, not always smoothly, it sometimes jerks in and out of turns which looks a bit odd but does maintain your preset height. [Edit: today I limited RTH to 30% roll and the RTH circling was a bit smoother.] So compared to the Storm - I won't get into all the feature differences except to say the Arkbird has quite a few more features, but here are some significant safety improvements of this OSD over the Storm: - Storm will not engage balance mode or RTH if wings are not within 15 degrees of being level. The Arkbird is much safer in this regard and will more than likely bring your plane home safe if your video cuts out and/or the plane hits strong turbulence and goes sideways. - Storm does not have throttle management. Again, if you lose link, the Storm relies on you having set your failsafe throttle to something appropriate. If flying into a strong headwind, you may have set too low a throttle to get home. The Arkbird will work to your minimum safe groundspeed and increase throttle as required. - A feature the Storm has which I hope Arkbird can adopt in future updates is being able to switch between display modes in flight so you can have the uncluttered 'simple' view for part of the flight. Not sure how they would program this though... maybe similar to gyro search cancel: ch5 0% + ch6 100% and switched when you go >75% L+R yaw within 2 seconds. - An issue I will not miss that the Storm had was drifting pitch/roll calibrations. I set neutral point for straight & level flight at home, went out to fly in 34 degree sun and there was no drift with the Arkbird. Overall, I have more trust in this OSD to bring my FPV money pit home than with the Storm. Once I've worked out how to give the gyro more control authority I'll be even happier. Yet to try waypoint flying or fence mode but no doubt these will work as advertised too. |
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I came across this thread, in my search for an new OSD. Nice video, all explained well. (nice location btw). After watching your video, and reading the manual, one question came to my mind. You are talking about 4 flightmodes (manual, alltitude, gyro, and return home). In the manual they are talking about only 3 modes. I like this OSD a lot, i found it during my search for a Skylark OSD, with RTH. This looks more solid to me. Thanks. |
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Australia, NSW, Springwood
Joined Dec 2012
130 Posts
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In the menu system, you can swap the gyro mode out with a couple of others like waypoints or fence mode. |
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Depth analysis of flight control (balancer) software technology Share Arkbird flight control design experience Arkbird flight control test flight commissioning starting in 2010, initially by Jiangnan Big Brother, the exchange of queens and discussion help (when doing open source version of the infrared), they were pretty good, to express my sincere gratitude to them, and would like to share flight control design, debugging experience, test data. For a deeper understanding of flight control some help. A. The difference and importance of the software Three foreign open source flight control, looks almost, but the performance and prices vary greatly. Why? Read open source, the KK Flight Control, only about 200 lines, MK has more than 4,000 lines of software is the real key to distinguish between the flight control. The hardware system board as long as 10 days, the software debugging ranging from six months to more than a year, It is no exaggeration to say that the hardware, peripherals bottle of software is the bottle of wine. And most users smoke and mirrors, the fly can not see the difference between the control software. Software adjust the year? Exaggerated, right? To debug it? Please read on: II. There is no good algorithm, sensors and consequently undetectable The Throttle larger sensors become miserable. Different filtering algorithm, shown in blue, red, yellow, brown a few lines (four values of the great difference between the average, the value of the average, 16 average, Kalman filtering). Even if the sensor selection, different engineers selected algorithm is different, very different. Seismic performance, will be completely different. Do UAV will the famous Kalman algorithm, Arkbird use a "simplified" version of the Kalman algorithm. The algorithm benefits from a confusion of values, to find the true value. In order to carry out the algorithm, you want to debug months. III. Interfere with the acceleration of the impact Flight Control gravity measured vertically, sometimes very tricky. Such as sitting in a roller coaster car acceleration was "pushing back" turn was "thrown out", hang a pendant on the roller coaster, the pendant will be thrown upside. Gravity determination, it will be very accurate. Interference acceleration up to 3-4 times gravity. Very scary, If you do not do software estimation and compensation, gravity will be completely drowned out most of the flight control, acceleration health value "a display, but this value is not calculating the standard, the same flight, A fly control "health value" to 0, but the B Flight Control "health value" 50, which is also related with the engineers to design, debug. Of course, there are a lot of flight control is not to compensate. This mold Friends of flight shots, you can see more than 139km / h, the health value of only 5. IV. Attitude solution Just said easy to inaccurate sensor, then this is not an accurate measurement value calculation of flight attitude Euler angles, quaternion algorithm (divided into first, second, some UAVs with 16 order), different attitude solution approach, the accuracy is also different, take a look at the following figure the goodness of fit of the two curves. These differences are dynamic error means that the ground can not see, only fly to see that: In order to do more accurate, but also commissioning several months. V. PID - flight control algorithms " Baidu Library Search "PID" paper, the results of 1,453,197. PID variety. Simple differential forward fuzzy control, neural network control, adaptive (self-learning) control ........ I fuzzy control of a soft spot for different designers will select a different algorithm. The PID regulator needs an engineer long-term experience. Usually to measure the system response curve analysis system poles (shock point), engaged in UAV brothers also do matlab simulation, draw a lot of response plans, pole analysis. Write a lot of papers. Then adjust the tone, and finally one day, found the tone very stable, like this picture below, the fuzzy control curve than "change the PID control curve small shocks, more stable. Upgrade point differential forward (to avoid the control value mutation), increase the variety of intelligent control, limiter like. Spend so much time tune this what use is it? Good tune, take a look at the beautiful the large Xinjiang's four-axis "snaps" foreigners playing table tennis with four axes, to build a house with four axes, is quite stable, with like still locked up in the air. Six. About spiral stall Breeze +2212 motor +2200 mah battery, quite good flying, I believe very few people can fly to spiral out. But when Arkbird tune PID in 11 years in July, actually be able to breeze fly spiral. The following video, it can be seen that the spiral is "very strange" state. And snails so probably not the reason of the aircraft itself. Check data said spiral flow separation, the rudder is invalid. For example, get threw poker. If poker "cut wind throw, you can fly very far; poker" airflow separation, then it will be like a piece of paper falling. So in PID control algorithm to increase the way to prevent flow separation (slow control), and solved the problem. Was asked Arkbird why Placing airspeed gauge, of course, not because of our technology is bad, not do this. But for UAV and large aircraft, the airspeed slow very dangerous, easy to stall, increase the airspeed gauge can effectively prevent large aircraft stall. For small model aircraft, and a little bit of throttle is not easy "flow separation" or "stall". Optimized control algorithm, not the one case Arkbird user feedback spiral, stall airspeed gauge to temporarily little role. VII. Other software details The above said the same hardware, different software caused a big difference, or even several times the difference. In addition, there are more details, such as elevator - aileron mixed control (turn lever), throttle - elevator mixing (fuel rod) ... These software effort, might do for a few months, users not see that. KK flight control 200 line program, the same as it was able to tune Detuo controlled flight, the foreign Niubi flight control, also off control flight (even playing table tennis), So maybe, flight control, good or bad, to see the flight video, is not a true hand contrast, might not objective. Finally, sharing just mentioned, sensor vibration test data, a total of 30 documents, consisting of various sensor test data. Help you DIY flight control. DIY flight control, and more than we imagined. A few days ago, a flight control DIY group, nearly 200 people. I believe each person to do the flight control, all love flying, love technology. |
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Joined Dec 2006
402 Posts
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Remember if you have oscillation problems on the aileron to extend the throws as much as you can, I mean top lower holes on servo arm and top hole on horn. |
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Joined Jun 2011
40 Posts
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Thanks, I rewired them following the manual,everything works now, will be maiden very soon. What I did wrong before was I wired it like g-osd where the v.out and camera signal wire plug into video tx using 'y' cable. With arkbird, camera goes in v- in, v-out goes in v.tx. The video tx supply 5v to camera.
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Australia, NSW, Springwood
Joined Dec 2012
130 Posts
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Quote:
Fatshark and IRC VTXs have 5v output, so you could power the VTX through the Arkbird's 12v/video plugs, then power the cam off the VTX's 5v line? |
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Australia, NSW, Springwood
Joined Dec 2012
130 Posts
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Failsafe is a function of the receiver. Do you have the option of buying a failsafe Rx to match your Tx? |
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Joined Dec 2006
402 Posts
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I can't comprehend a difference as balance would need gyros to operate? |
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