Yesterday a few  of the UK Ardupilot group (Malcolm, Dean & I) arrived at a flight field ready to take a look at and test the DJI Innovations WKH on a traditional Heli, this was installed on a Spectra petrol Heli, it was sent out to hold its position in GPS ATTI mode, we filmed the Spectra to show how it got on! Dean had his OctoCopter there so we tried the "point of interest" function on the DJI Wookong M to add a new angle to the video & show the WKH in position hold.

 
Both the WKH & WKM both performed without fault, the WKH held the traditional Heli in position from the start of the video until the end without pilot intervention!


One the more interesting points about the WKH and the Heli was the level of vibration coming from the engine which was very high frequency, if you have ever flown Nitro / petrol engine planes before you will know how much vibration is produced from these single piston engines. The WKH IMU did not seem to mind any of these vibrations passing through the frame. At the start of the video you will see the IMU is placed within a few cm of the engine.


We also tried the Atti mode and it worked just as well as GPS ATTI, the Heli was very stable and easy to fly in all modes including "manual".

 

Regards

 

Martin.

Views: 1497

Comment by Rana on August 13, 2012 at 3:26am

Excellent performance by DJI !

Yesterday, one of my friend Col. Kapur, flight tested the DJI Wokoong Quad, video is not of high quality, taken from Android Tab. See how precision extremely low altitude, almost close to ground and what an accurate GPS position lock.

http://www.youtube.com/watch?v=BR3-3qMHUcw

Comment by Rui Manuel Cravo Marques on August 13, 2012 at 3:40am

Great performance indeed :) however I'm confident that APM will eventually get here... and with a lot more features !!! Bravo wk.

Comment by Rana on August 13, 2012 at 3:46am

I wish too !


Moderator
Comment by Hai Tran on August 13, 2012 at 5:06am

I have a WK-H on my Trex 600E, it works well except no RTH!

Comment by Rob_Lefebvre on August 13, 2012 at 6:06am

Wow!  Great video guys (Malcolm, you traitor! ;)  ;)  

So you mounted it directly on the motor mounting plate with nothing other than some two-sided tape?!  Unreal.

That is of course a great performance from both systems.  How did you said another flying vehicle as the POI?  I assume you just knew the coordinates of the heli, and used those as the POI for the Octo?

BTW, which Octo frame and gimbal is that?  Seemed to work well.

The Heli is generally rock steady in the air, however I did notice just a bit of tail waggle, similar to the problem I was wanting to fix on Arducopter.  I'm not sure if you noticed, but I could see it a bit, and that's what I'm talking about when I say my heli has a bit of waggle.

Well, the gloves have been dropped. ;)

Comment by Mike on August 13, 2012 at 6:23am

The pursuit of 'features' has been the downfall of many open source projects. Get the basics working first....

Comment by Crasher on August 13, 2012 at 7:03am

@RL

The latest version of Wookong Firmware allows you to set a POI in the air by putting the copter at the POI and toggling a mode switch. The copter can then move back and around that POI. I'm sure MArtin will fill you in on any details.


Moderator
Comment by Hai Tran on August 13, 2012 at 7:05am

@Crasher does this POI apply to WK-H?  There are quite a few features missing in WK-H that WK-M has. Quite deceptive.

Comment by Rob_Lefebvre on August 13, 2012 at 7:45am

Hai, if WK-H doesn't have RTH, that's really bad in my opinion.  Does it have waypoints?  Is this the $5000 system or is that the Ace One?

@Mike, I agree.  The problem is there's not enough people working on Trad Helis.  They are really expensive and time consuming to fix, so it's not conducive to playing around with code and just having fun, which is what the OS project is all about.

IMO, the Arducopter performance on a Trad Heli should be very comparable to the WK-H, IF we could solve the damn vibration problem.  When my 600 with APM1 is flying well, it's far, far more stable and wind-resistant than my quad.  And I know how well my quad Loiters now with the Ublox GPS.  So put the Ublox on the 600 and it'll be awesome.

I had mine flying really really well, hands off hovering other than the wind pushing it around...Until the vibes cause it to lean and it crashes!

Now the question is, what is responsible for the WK-H's vibration performance?  Is it hardware, or software?  Do they have better Accels/Gyros?  Or just better usage in the code?  I know that the IMU is mounted on/in a small  metal cube inside that plastic box, with foam between the plastic and the metal cube.  The cube gives it some mass to help dampen vibrations.  And I think they have 8 little squares of foam, one on every corner, which is a great design because it stops rotational vibration from becoming horizontal accelerations and vice-versa.

I recently came to the realization of why some of my mounts have failed.  It's because I am using the holes in the board to bolt to my dampers.  It results in a narrow footprint, and the APM is sort of perched on top, it's like a Rolly-Polly toy.

I need to set the damper mounts wider than APM, by mounting the APM to a large flat aluminum plate with wideset mounting tabs.  But part of the problem with that has always been because I'm trying to squeeze the entire thing into the chassis of the heli which is narrow.  

The WK-H doesn't have that problem because the IMU is separate from the processor, so it's just this tiny little cube that's easy to mount.  The main processor is about the size of the APM, wide and flat, and you can mount it in any orientation as shown on Malcolm's heli.  

We've also been talking on the dev list about some changes to the DCM for the Trad Heli. Some of the default parameters might be optimized.

Comment by malcolm churn on August 13, 2012 at 10:54am

In no way have i given up on the APM Robert :)  I want to get it working.... so i'm all up for any changes to the code and testing.

The WK-H works well, the engine has a very slight misfire coming from the carb insulator block (air leak) which kicks the tail very slightly, i have a new one on order. I did change the some of the settings that the manual says to use for a flybarless 700.  Also i adjusted a few for the autopilot as well, i think i got it pretty well tuned. The wind on the day was going from zero to about 5 mph, it coped well with the changeable breeze. 

The failsafe just holds the heli in GPS Atti mode (loiter), it would be really good to have RTH and Land like the WK-M / Naza.

My impressions so far after just a week tuning and flying : 

It will cope easily with a single cylinder spark engine, nitro would be even better for it. 

The manual is easy enough to follow, there are a few standard settings in there to pick from: align 600 E to GSR260 gasser. The software like the manual is good, with a wizard to guide you through. I chose to use a flybarless head, which is an option in the software, it flys as well as any after market electronics. The governor is really good, but you can only set one head speed. No problem if you are using it for camera / drone work. I found the stated pitch curve a little soft for my liking, but would be great for a beginner. Saying that the manual states that you should fly your heli before fitting the WK-H to be sure that it is mechanically sound and vibration free. So a good degree of flying skill is required for that.

I raised my 10 amp reg to 6volt to lower the heat coming from it. Then used a 5.1v stepdown for the rudder servo. My battery pack is a 7.4 volt 3800 lipo 

Fitting it to the helicopter is very easy, the kit comes supplied with a boom clamp for the gps, double sided tape for control unit and LED, i used futaba gyro pads on the IMU. It was too big for my gyro mount which is why its mounted next to the engine, the leads are long enough for the biggest of helis. 

All in its a very good out of the box system. 

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